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Light measuring device for flash photography |
| RE32437 |
Light measuring device for flash photography
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| Patent Drawings: | |
| Inventor: |
Taniguchi, et al. |
| Date Issued: |
June 9, 1987 |
| Application: |
06/701,780 |
| Filed: |
February 13, 1985 |
| Inventors: |
Taniguchi; Nobuyuki (Tondabayashi, JP)
Yuasa; Yoshio (Osaka, JP)
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| Assignee: |
Minolta Camera Kabushiki Kaisha (Osaka, JP) |
| Primary Examiner: |
Perkey; W. B. |
| Assistant Examiner: |
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| Attorney Or Agent: |
Price, Gess & Ubell |
| U.S. Class: |
250/214P; 315/151; 315/155; 315/158; 315/241P; 356/215; 356/222; 396/157; 396/166 |
| Field Of Search: |
354/414; 354/415; 354/416; 354/417; 354/429; 354/433; 354/434; 354/474; 354/475; 354/127.1; 354/127.11; 354/432; 354/127.12; 354/145; 356/215; 356/218; 356/221; 356/222; 356/226; 315/241P; 315/151; 315/155; 315/158 |
| International Class: |
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| U.S Patent Documents: |
4291979 |
| Foreign Patent Documents: |
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| Other References: |
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| Abstract: |
The disclosure is directed to an improved light measuring device which is used in flash photography for measuring a preliminary flash light to obtain camera exposure informations for photography under a primary flash light. The device is so arranged as to preliminarily obtain information of light amount contributing to photographing, with respect to each portion or area of a scene to be photographed or object field, in taking photographs with the employment of the auxiliary light. |
| Claim: |
What is claimed is:
1. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information for photography under a primary flashlight, comprising:
a plural means for receiving light coming from various areas of the object field, respectively;
means for producing outputs in response to said plural means, respectively;
means for respectively integrating the individual outputs of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first group of signals, respectively;
means for obtaining a second group of signals respectively including light intensity information of said various areas without the influence of the preliminary flash light, by utilizing the individual outputs of said producing means,respectively;
means for setting an exposure time signal; and
means for respectively processing at least each of said first group of signals and each of said second group of signals with said exposure time signal to respectively obtain information of the amount of light effective in determining the exposureon various areas of the photosensitive surface corresponding to said various areas of the object field upon photography under the primary flash light.
2. Light measuring device according to claim 1, wherein said light receiving means each include a photosensitive element for measuring a part of the object field.
3. Light measuring device according to claim 2, wherein said processing means includes means for calculating an average of said information of said light amount.
4. Light measuring device according to claim 3, wherein said average is the weighted average.
5. Light measuring device according to claim 3, wherein said average is the geometrical average.
6. Light measuring device according to claim 3, wherein said average is the harmonic average.
7. Light measuring device according to claim 3, wherein said processing means further includes means for calculating a ratio of one of said information of light amount to said average.
8. Light measuring device according to claim 3, further comprising means for setting a sensitivity signal indicative of the sensitivity of the photosensitive surface to be processed by said processing means, and wherein said processing meansincludes means for calculating an aperture value in response to said average and said sensitivity signal to achieve an averaged optimum exposure for the whole object field.
9. Light measuring device according to claim 2, further comprising means for comparably indicating exposure information each corresponding to each of said various areas of the object field in response to said information of light amount,respectively.
10. Light measuring device according to claim 1, wherein said processing means includes means for maintaining said first and second groups of signals during a change in the exposure time signal setting to obtain said information of light amountwith the values thereof modified by the change in the exposure time signal setting.
11. Light measuring device according to claim 1, further comprising means for setting a change in a guide number between the preliminary and primary flashings, and wherein said processing means includes means for further processing said changein guide number to obtain said information of light amount.
12. Light measuring device according to claim 1 further comprising means for selecting one of said information of light amount, and means for setting a sensitivity signal, and wherein said processing means includes means for calculating anaperture value in response to said selected information of light amount and said sensitivity signal to achieve an optimum exposure for an area of the object field corresponding to said selected information of light amount.
13. Light measuring device according to claim 1, wherein said processing means includes means for calculating a ratio of one to another of said information of light amount.
14. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information for photography under a primary flash light, comprising:
at least a pair of means for receiving light coming from a pair of areas of the object field, respectively;
means for producing outputs in response to said pair means, respectively;
means for respectively integrating the individual outputs of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first group of signals, respectively;
means for obtaining a second group of signals respectively including light intensity information of said pair of areas without the influence of the preliminary flash light, by utilizing the individual outputs of said producing means,respectively;
means for setting an exposure time signal; and
means for processing said first and second groups of signals with said exposure time signal to obtain a ratio of a first light amount to a second light amount, said first and second light amounts being effective in determining the exposure on apair of areas of the photosensitive surface corresponding to said pair of areas of the object field upon photography under primary flash light, respectively.
15. Light measuring device according to claim 14, wherein said processing means includes means for warning when said ratio is outside a given range.
16. Light measuring device according to claim 14, further comprising means for setting a change in guide number between the preliminary and primary flashings, and wherein said processing means includes means for further processing said change inguide number to obtain said ratio.
17. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information for photography under a primary flash light, comprising:
at least a pair of means for receiving light coming from a pair of areas of the object field, respectively;
means for producing outputs in response to said light receiving means, respectively;
means for respectively integrating the individual outputs of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first group of signals, respectively;
means for obtaining a second group of signals respectively including light intensity information of said pair of areas without the influence of the preliminary flash light, by utilizing the individual outputs of said producing means,respectively;
means for setting one of an exposure time signal and a signal indicative of a change in guide number between the preliminary and primary flashings; and
means for processing said first and second groups of signals with the signal set by said setting means to obtain the other of said exposure time signal and said signal indicative of the change in guide number so as to achieve a given ratio of afirst light amount to a second light amount, said first and second light amounts being effective in determining the exposure on a pair of areas of the photosensitive surface corresponding to said pair of areas of the object field upon photography underthe primary flash light, respectively.
18. Light measuring device according to claim 17 further comprising means connected to said processing means for setting said ratio.
19. Light measuring device according to claim 17, wherein one of said light receiving means includes a photosensitive element for averaging light measurement.
20. Light measuring device according to claim 17, wherein said processing means includes means for identifying that the obtained signal by said processing means is impractical, and means for replacing the obtained signal by a signal closest tothe obtained signal in the practical range.
21. Light measuring device according to claim 20, wherein said processing means includes means for calculating the ratio of said first light amount to said second light amount in response to said first and second groups of signals, the signalset by said setting means and said closest signal, and means for warning when said ratio is outside a given range.
22. Light measuring device according to claim 20, wherein said processing means includes means for substituting a signal for the signal set by said setting means, when the obtained signal is replaced with said closest signal, so as to achievesaid given ratio in response to said first and second groups of signals, said closest signal and said substituted signal.
23. Light measuring device according to claim 17, wherein said processing means includes means for detecting that the given ratio is impossible by any means.
24. Light measuring device according to claim 23 further comprising means for adjusting a sensitivity signal, and wherein said processing means includes means for calculating an aperture value in response to, at least, one of said first group ofsignals, a corresponding one of said second group of signals, the signal set by said setting means, said sensitivity signal and a predetermined value assumed in place of a value of the signal to be obtained by said processing means, if said detectingmeans detects that the given ratio is impossible.
25. Light measuring device according to claim 23, wherein said processing means includes means for calculating the ratio of said first light amount to said second light amount in response to said first and second groups of signals, the signalset by said setting means and said predetermined signal, and means for warning when said ratio is outside a given range.
26. Light measuring device according to claim 17, further comprising means for adjusting a sensitivity signal and means for selecting one of said areas of the object field, and wherein said processing means includes means for calculating anaperture value in response to one of said first group of signals corresponding to the selected area of the object field, a corresponding one of said second group of signals, said exposure time signal, said signal indicative of a change in guide numberand said sensitivity signal.
27. Light measuring device according to claim 17, wherein said light receiving means includes three or more light receiving elements corresponding to three or more areas of the object field, and wherein said light measuring device furthercomprises means for selecting the pair of areas among said three or more areas.
28. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information for photography under a primary flash light, comprising:
at least a pair of means for receiving light coming from a pair of areas of the object field, respectively;
means for producing outputs in response to said light receiving means, respectively;
means for respectively integrating the individual outputs of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first group of signals, respectively;
means for obtaining a second group of signals respectively including light intensity information of said pair of areas without the influence of the preliminary flash light, by utilizing the individual outputs of said producing means,respectively; and
means for processing at least said first and second groups of signals to obtain camera exposure information.
29. Light measuring device according to claim 28, wherein said processing means includes means responsive to said first and second groups of signals for obtaining an exposure time signal so as to achieve a given ratio of a first light amount toa second light amount, said first and second light amounts being effective in determining the exposure on a pair of areas of the photosensitive surface corresponding to said pair of areas of the object field upon photography under the primary flashlight, respectively.
30. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information for photography under a primary flash light, comprising:
means for receiving light coming from the object field;
means for producing an output in response to said light receiving means;
means for integrating the output of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first signal;
means for obtaining a second signal including light intensity information without influence of the preliminary flash light, by utilizing the output of said producing means;
means for setting an exposure time signal;
means for setting an aperture size signal;
means for setting a sensitivity signal; and
means for processing said first and second signals, said exposure time signal, said aperture size signal and said sensitivity signal to obtain a signal indicative of a difference in guide number between the preliminary and primary flashings so asto achieve an optimum exposure.
31. Light measuring device according to claim 30 further comprising means for controlling the primary flashing in response to said signal indicative of the difference in guide number.
32. Light measuring device according to claim 30 further comprising means for warning when the difference in guide number is impractical.
33. A light measuring system, adapted for use with a camera having a variable aperture and shutter speed and an electronic flash device for flash photography, to ensure proper contrast in the object scene comprising:
means for producing a preliminary flash of light towards the object scene;
means for measuring the preliminary flash of light reflected from discrete predetermined areas of the object scene and producing corresponding preliminary light signals representative of the object scene;
means for measuring ambient light reflected from the discrete predetermined areas of the object scene and producing corresponding ambient light signals representative of the object scene;
means for setting a predetermined exposure time signal, and
means for producing the preliminary light signals and the ambient light signals relative to the exposure time signal to determine the proper light exposure of a photosensitive member in the camera to record the object scene.
34. The invention of claim 33 further including display apparatus for providing indicia indicating the exposure condition of the predetermined areas.
35. The invention of claim 33 further including means for varying the intensity of the flash in response to the determination of the proper light exposure. .Iadd.
36. Light measuring device for use in flash photography, which measures preliminary flash light and ambient light to obtain camera exposure information for photography under a mixture of primary flash light and ambient light, comprising:
means for measuring light to produce a first output with the influence of the preliminary flash light and a second output without the influence of the preliminary flash light with respect to a plurality of selected areas of the object field,respectively;
first group of means for storing the first output with respect to the plurality of areas, respectively;
second group of means for storing the second output with respect to the plurality of areas, respectively;
means for manually setting the exposure time;
means for calculating exposure information with respect to the plurality of areas in response to the storage of the first and second outputs for the corresponding areas in the first and second groups of storing means and the exposure time set bythe setting means, respectively; and
means, responsive to the calculating means, for comparably indicating the exposure information with respect to the plurality of areas. .Iaddend. .Iadd.37. Light measuring device according to claim 36 further comprising means for setting thefilm speed, wherein the calculating means is further responsive to the film speed setting means to calculate aperture values as the exposure informations, and the indicating means includes for displaying the aperture values for the plurality of areas. .Iaddend. .Iadd.38. Light measuring device according to claim 36, further comprising means for setting a relation between the amount of preliminary flash light and that of primary flash light, wherein the calculating means is further responsive to therelation setting means to calculate the exposure informations. .Iaddend. .Iadd.39. Light measuring device according to claim 36, further comprising second means, responsive to the first and second storing means and the exposure time setting means, forcalculating the flash light amount and the ambient light amount with respect to at least selected one of the plurality of areas, and second means, responsive to the second calculating means, for indicating the relation between the flash light amount andthe ambient light amount with respect to the selected one of the plurality of areas. .Iaddend. .Iadd.40. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information forphotography under a primary flash light, comprising:
means for measuring light to produce an output with respect to a plurality of selected areas of the object field, respectively, including an integrating means operative during a given period of time including at least the duration time of thepreliminary flash light;
a group of means for storing the output of the measuring means with respect to the plurality of areas, respectively;
means, responsive to the group of storing means, for respectively obtaining informations of amount of light effective in determining the exposure on various areas of the photosensitive surface corresponding to the plurality of areas of the objectfield upon photography under the primary flash light; and
means, responsive to the obtaining means, for comparably indicating the exposure informations each corresponding to each of the plurality of areas
of the object field. .Iaddend. .Iadd.41. Light measuring device for use in flash photography, which measures a preliminary flash light to obtain camera exposure information for photography under a primary flash light, comprising:
means for receiving light coming from various areas of the object field, respectively;
means for producing outputs in response to said receiving means, respectively;
means for respectively integrating the individual output of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first group of signals, respectively;
means for obtaining a second group of signals respectively including light intensity information of said various areas without the influence of the preliminary flash light, by utilizing the individual outputs of said producing means,respectively;
means for setting an exposure time signal; and
means for respectively processing at least each of said first group of signals and each of said second group of signals with said exposure time signal to respectively obtain information of the amount of light effective in determining the exposureon various areas of the photosensitive surface corresponding to said various areas of the object field upon photography under the primary flash light..Iaddend. |
| Description: |
BACKGROUND OF THE INVENTION
The present invention generally relates to photography and more particularly, to a light measuring device for use in flash photography to be effected by firing a flash light source (referred to as an auxiliary light source hereinbelow) underambient light.
Generally, the purpose for employing an auxiliary light source under ambient light conditions is to adjust contrast between different portions or areas in a scene to be photographed or the object field. For example, when a main object to bephotographed is dark as compared with the background due to rear light or the like, the brightness of the main object can be increased with the use of the auxiliary light for adjusting the contrast with respect to the background as desired.
However, there has not been conventionally proposed any satisfactory light measuring device which is suitable for taking photographs by adjusting the contrast between respective portions in the scene to be photographed as desired by aphotographer, with the employment of the auxiliary light source. Up to the present, for taking photographs as required, it has been a common practice that a photographer well experienced in photographing adjusts the lighting based on his experience. However, the practice as described above is nothing but a qualitative control of the contrast after all, and the quantitative control thereof has not been actually effected. Furthermore, it has been extremely difficult for photographers in general evento control the contrast qualitatively.
SUMMARY OF THE INVENTION
Accordingly, an essential object of the present invention is to provide an improved light measuring device which is capable of preliminarily obtaining information of the amount of light contributing to photographing, with respect to each portionor area of a scene to be photographed or object field when employing an auxiliary light.
Another important object of the present invention is to provide an improved light measuring device of the above described type which is capable of obtaining an average value of said information thus obtained, and displaying said informations forcomparison.
A further object of the present invention is to provide an improved light measuring device of the above described type which is capable of preliminarily finding the contrast between respective portions or areas in a scene to be photographedduring photographing employing the auxiliary light.
A still further object of the present invention is to provide an improved light measuring device of the above described type which is capable of preliminarily obtaining exposure information for achieving set contrast, judging whether or not thevalue thus obtained can be effected, and also, detecting that the exposure information for achieving the set contrast is impractical.
A further object of the present invention is to provide an improved light measuring device of the above described type which is capable of achieving optimum exposure in photographing employing an auxiliary light.
Still another object of the present invention is to provide an improved light measuring device of the above described type which may be applied to an exposure control device of a photographic camera.
In accomplishing these and other objects, according to one preferred embodiment of the present invention, there is provided a light measuring device to be used in flash photography for measuring a preliminary flash light to obtain camera exposureinformation for photography under a primary flash light, which includes a plurality of means for receiving light coming from various areas of the object field, respectively, means for producing outputs in response to said plurality of means,respectively, means for respectively integrating the individual outputs of said producing means during a predetermined period of time including at least the duration time of the preliminary flashing to obtain a first group of signals, respectively, meansfor obtaining a second group of signals respectively including light intensity information of said various areas without the influence of the preliminary flash light, by utilizing the individual outputs of said producing means, respectively, means forsetting an exposure time signal, and means for respectively processing at least each of said first group of signals and each of said second group of signals with said exposure time signal to respectively obtain informations of light amount effective indetermining the exposure on various areas of the photosensitive surface corresponding to said various areas of the object field upon photography under the primary flash light.
By the arrangement according to the present invention as described above, an improved light measuring device, which makes it possible to take photographs at a contrast of a desired value, has been advantageously presented, with substantialelimination of disadvantages inherent in the conventional light measuring devices of this kind.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which;
FIG. 1 is an electrical block diagram showing the construction of a light measuring device according to one preferred embodiment of the present invention,
FIG. 2 is an electrical block diagram showing a modification of the circuit portion for an average light amount in the arrangement of FIG. 1,
FIG. 3 is a block diagram similar to FIG. 2, which particularly shows another modification thereof for obtaining the average light amount in APEX value,
FIG. 4 is an electrical block diagram illustrating the construction of a circuit portion for calculating aperture values to obtain proper exposure based on the light amount at two spots and the average light amount as obtained in the circuitarrangement of FIG. 1, 2, or 3,
FIG. 5 is a schematic side sectional view of a light measuring meter showing an optical system thereof to which the present invention is applied,
FIG. 6 is a schematic top plan view illustrating light receiving portions of respective photoelectric elements employed in the arrangement of FIG. 5,
FIG. 7 is a schematic side elevational view of the light measuring meter of FIG. 5,
FIG. 8 is an electrical circuit diagram showing the internal circuit construction of the light measuring meter of FIG. 7,
FIG. 9 is an electrical circuit diagram showing specific examples of circuit constructions of light measuring circuits and multiplexers employed in the circuit arrangement of FIG. 8,
FIGS. 10(A), 10(B), 11(A), 11(B), 12(A), 12(B), 12(C), 13, and 14 are flow-charts explanatory of functions of a micro-computer employed in the circuit arrangement of FIG. 8,
FIG. 15 is a fragmentary side elevational view showing, on an enlarged scale, a modification of a display portion of the light measuring meter of FIG. 7,
FIG. 16 is an electrical block diagram showing a modification of the light measuring circuit of FIG. 9,
FIG. 17 is an electrical block diagram showing the construction of a light measuring device according to a second embodiment of the present invention,
FIG. 18 is an electrical block diagram explanatory of the contents of calculation at a calculating section A employed in the circuit arrangement of FIG. 17,
FIG. 19 is a diagram similar to FIG. 18, which particularly explains the contents of calculation at a calculating section B employed in the circuit arrangement of FIG. 17,
FIG. 20 is an electrical block diagram showing a specific example of a logic circuit B17 which may be employed in the circuit arrangement of FIG. 19,
FIG. 21 is a diagram similar to FIG. 20, particularly showing a specific example of a logic circuit B18 which may be employed in the circuit arrangement of FIG. 19,
FIG. 22 is an electrical block diagram explaining the contents of calculation at a calculating section E employed in the circuit arrangement of FIG. 17,
FIGS. 23, 24 and 25 are electrical block diagrams explaining the contents of calculations at a calculating section F employed in the circuit arrangement of FIG. 17,
FIG. 26 is a diagram similar to FIGS. 23 to 25 which particularly shows the contents of calculation at a calculating section G employed in the circuit arrangement of FIG. 17,
FIG. 27 is a view similar to FIG. 5, which particularly relates to the second embodiment of FIG. 17,
FIG. 28 is a schematic top plan view illustrating light receiving portions of respective photoelectric elements employed in the light measuring meter of FIG. 27,
FIG. 29 is a fragmentary side elevational view showing, on an enlarged scale, a display mode in the light measuring meter of FIG. 27,
FIG. 30 is a block diagram similar to FIG. 1, which particularly shows a third embodiment thereof,
FIG. 31 is also a block diagram similar to FIG. 30, which particularly shows a modification thereof,
FIG. 32 is a flow-chart showing processes of calculations in the light measuring arrangement of FIG. 31, and
FIG. 33 is a block diagram showing a modification of a part of the circuit arrangement of FIG. 31.
Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals and symbols throughout several views of the accompanying drawings.
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment
The basic concept of the present invention is to control the contrast of objects in a scene to be photographed through employment of an auxiliary light source, for example, a flash light emitting device such as an electronic flash or the like. More specifically, on the assumption that brightness at two portions in a scene to be photographed are respectively represented by 2.sup.Bv1 and 2.sup.Bv2, and reflected light amounts from the two portions by an auxiliary light source are denoted by2.sup.Qvf1 and 2.sup.Qvf2, which exposure time being represented by 2.sup.-Tv, the ratio of light amounts contributing to the exposure of a photosensitive member by the two portions may be represented by
Here, upon definition as
the contrast of the two portions reproduced on the photosensitive member will be
which may be denoted in the APEX systems as follows.
where Qvt1 and Qvt2 are equivalent to values in the APEX system of the light amounts of two photographic objects contributing to the exposure for the photosensitive member.
Accordingly, it becomes possible to control the contrast by controlling the exposure time and light emitting amount of the auxiliary light source. Moreover, the exposure level may be controlled through adjustments of diaphragm aperture values.
Referring now to the drawings, there is shown in FIG. 1 a general circuit arrangement of a light measuring device for photographing by the use of an auxiliary light according to a first embodiment of the present invention.
The light measuring device of FIG. 1 generally includes light measuring circuits 1 and 2 respectively having photoelectric elements P1 and P2 for measuring light intensities of different portions in the scene to be photographed, and coupled,through change-over switches S1 and S2, to corresponding integration circuits 3 and 5 which produce signals corresponding to logarithmically compressed values of the received light amounts and which are respectively associated with sample-and-holdcircuits 4 and 6 for sampling and holding the outputs of the light measuring circuits 1 and 2, and also a flash light emitting device FL which is associated with the light measuring circuits 1 and 2 and integration circuits 3 and 5 through a triggerswitch S3 and arranged to be normally open so as to be closed for a predetermined period of time upon reception of a starting signal (not shown) for the light measuring.
The change-over switches S1 and S2 are normally connected to terminals A1 and A2 leading to the sample hold circuits 4 and 6, and adapted to be changed over to terminals F1 and F2 connected to the integration circuits 3 and 5 for a predeterminedperiod of time by the starting signal for the light measuring. The integration circuits 3 and 5 and sample-and-hold circuits 4 and 6 are connected to a analog multiplexer 7 which is further coupled to a digital de-multiplexer through an A-D converter 8. It is to be noted that signal lines marked with slashes represent those dealing with digital signals with a plurality of bits. Connected to the de-multiplexer 9 are a register 10 in which digital data corresponding to the signal Qv1 from the integrationcircuit 3 are set, another register 11 in which digital data corresponding to the signal Qv2 from the integration circuit 5 are set, a still another register 12 in which digital data corresponding to the signal Bv1 from the sample-and-hold circuit 4 areset, and a further register 13 in which digital data corresponding to the signal Bv2 from the sample-and-hold circuit 6 are set. The registers 10, 11, 12 and 13 are further coupled as shown to subtractors or subtraction circuits 17, 18, 15 and 16, ROM19 and 20, adders or addition circuits 21 and 22, subtraction circuits 24, 25, 27, 28, 29 and 30, ROM 31 and 32, addition circuits 33, 34 and 35, a divider 36, and subtraction circuits 37, 38 and 39, while a fixed data output circuit 14 for producingfixed data corresponding to the APEX value Tvc of the integration time is connected to the subtraction circuits 15 and 16, and a circuit 23 for producing a data representative of .DELTA.f which corresponds to a change in the guide number in APEX systembetween the preliminary flashing and a primary flashing, is coupled to the subtraction circuits 24 and 25, with an exposure data output circuit 26 for producing data corresponding to the APEX value Tvs for the set exposure time being coupled to thesubtraction circuits 27 and 28.
The subtraction circuits 15 to 18, ROM 19 and 20, addition circuits 21 and 22, subtraction circuits 24, 25, 27, 28, 29 and 30, ROM 31 and 32, addition circuits 33 to 35, divider 36, and subtraction circuits 37 to 39, etc. are blocks forcalculations, and represented in the manner as in the diagram of FIG. 1 for better understanding of the contents of calculations, but in the actual production of the light measuring device according to the present invention, instructions may be preparedbased on a flow of calculation shown in the diagram through employment of a micro-computer. It should also be noted that blocks for controlling change-over of the switches S1, S2 and S3, timing for controlling the sample-and-hold circuits 4 and 6, dataselection signal and signal change-over of the multiplexer 7 and de-multiplexer 9, timing for the A-D conversion, etc. are omitted here for brevity, because preparation of a timing controller for controlling each block at timings as described in thefollowing description of functionings is obvious to those skilled in the art, and such control may also be readily effected through employment of a micro-computer.
By the above arrangement, upon depression of a light measuring button (not shown) in the first place, the switch S1 is connected to the terminal F1 and the switch S2, to the terminal F2 for a predetermined period of time (i.e. the integrationtime described earlier, Tvc in APEX value), with the switch S3 being closed for causing the flash light emitting device FL to emit light. The above integration time is arranged to be longer than the maximum light emitting time of the flash lightemitting device FL. After the predetermined period of time, since the switches S1 and S2 are respectively connected to the terminals A1 and A2 again, input signal to the integration circuits 3 and 5 is suspended, and thus, the integration output isregarded as being sampled and held. Subsequently, the outputs of the light measuring circuits 1 and 2 are sampled and held by said circuits 4 and 6.
Incidentally, the integration circuits 3 and 5 produce the logarithmically compressed values of the integrated values of the current corresponding to the output current from the photoelectric elements P1 and P2 in the light measuring circuits 1and 2, while the light measuring circuits 1 and 2 produce signals for the brightness of the object to be photographed in the APEX value. One example of a specific circuit arrangement for the above purpose is shown in FIG. 9.
On the assumption that the analog output of the integration circuit 3 is denoted by Qv1, and the output of the sample-and-hold circuit 4, by Bv1, the relation will be represented by
and when the output of the integration circuit 5 is represented by Qv2 and that of the sample-and-hold circuit 6 by Bv2, the relation will be
where Qvfm1 and Qvfm2 are reflected light amounts only by the flash light emitting device during the light measuring. More specifically, data for the brightness at the portions measured for the light intensities by the light measuring circuits 1and 2 in APEX value are respectively produced from the sample-and-hold circuits 4 and 6, while the light amounts from the two portions during the flash light emitting time are produced from the integration circuits 3 and 5.
When the sampling by the sample-and-hold circuits 4 and 6 are effected, the signal from the integration circuit 3 is first output from the multiplexer 7 so as to be subjected to the A-D conversion by the A-D converter 8, and upon completion ofthe A-D conversion, the digital data thereof are set in the register 10 through the demultiplexer 9. Subsequently, from the multiplexer 7, the signal from the integration circuit 5 is produced, and subjected to the A-D conversion, and the data thereofare set in the register 11. Thereafter, in the similar manner as described above, the A-D converted data of the output from the sample-and-hold circuit 4 are set in the register 12, while those from the sample-and-hold circuit 5 are set in the register13. Accordingly, the data corresponding to Qv1 are thus set in the register 10, those corresponding to Qv2, in the register 11, those corresponding to Bv1, in the register 12, and those corresponding to Bv2, in the register 13, and calculations areeffected by the subsequent circuits based on the above data.
The subtraction circuit 15 produces the data for Bv1-Tvc based on the data from the register 12 and data from the fixed data output circuit 14, while the subtraction circuit 16 develops the data for Bv2-Tvc in a similar manner. Meanwhile, thesubtraction circuit 17 carries out the calculation for
and the subtraction circuit 18 performs the calculation for
The data of .DELTA.11 and .DELTA.12 thus worked out are fed to the ROM 19 and 20 as address designating data for the data conversion ROM 19 and 20, from which, data for log.sub.2 (2.sup..DELTA.11 -1) and log.sub.2 (2.sup..DELTA.12 -1) areproduced. These data from the ROM 19 and 20 and the data of BV1-Tvc and Bv2-Tvc from the subtraction circuits 15 and 16 are forwarded to the addition circuits 21 and 22 for the calculations of
and thus, the reflected light amounts Qvfm1 and Qvfm2 resulting from the light emission by the flash light emitting device during the light measuring are worked out.
Hereinbelow, the process how the reflected light amounts Qvfm1 and Qvfm2 are worked out by the equations (6-1) and (6-2) will be explained.
Upon rewriting of the equations (4-1) and (4-2) into exponential form, the relations may be represented by
When Qv1 and Qv2 are eliminated for arrangement from the above equations (4'-1) and (4'-2) based on the equations (5-1) and (5-2) the relations will be
and by taking the logarithm of both sides of these equations to the base of 2, respectively, the equations (6-1) and (6-2) earlier described are obtained.
To the subtraction circuits 24 and 25, the data Qvfm1 and Qvfm2 from the addition circuits 21 and 22 and the data .DELTA.f from the data output circuit 23 are applied for calculations of
As described earlier, since the data .DELTA.f are defined to be a difference from the light emitting amount in an APEX system of the flash light emitting device during the light measuring time to the light emitting amount in the APEX systemthereof at the photographing time, the values Qvf1 and Qvf2 worked out by the equations (7-1) and (7-2) are equivalent to the reflected light amounts due to the flash light emission during photographing.
Meanwhile, to the subtracting circuits 27 and 28, the data Bv1 and Bv2 from the registers 12 and 13 and the data for Tvs in APEX value of the set exposure time from the exposure time data output circuit 26 are applied, with the data for Bv1-Tvsand Bv2-Tvs being produced from the respective subtraction circuits 27 and 28. The subtraction circuits 29 and 30 are applied with the data Qvf1 and Qvf2 from the subtraction circuits 24 and 25, and also with the data Bv1-Tvs and Bv2-Tvs from thesubtraction circuits 27 and 28 so as to effect the calculations for the equations
The data .DELTA.L1 and .DELTA.L2 thus worked out are equivalent to the ratio of the amount of contribution towards the exposure of the flash light to that of the ambient light or steady light for the respective two portions, or equivalent to thedifference of the contribution amounts in the APEX system, and normally referred to as "lighting contrast".
The data .DELTA.L1 and .DELTA.L2 for the lighting contrast from the subtraction circuits 29 and 30 are supplied as address data for the data conversion ROM 31 and 32, from which, the data for log.sub.2 (2.sup..DELTA.L1 +1) and log.sub.2(2.sup..DELTA.L2 +1) are produced. These data log.sub.2 (2.sup..DELTA.L1 +1) and log.sub.2 (2.sup..DELTA.L2 +1) from the ROM 31 and 32, and the data (Bv1-Tvs) and (Bv2-Tv2) from the subtraction circuits 27 and 28 are applied to the addition circuits 33and 34 for the calculations of the equations
and thus, the data Qvt1 and Qvt2 for the light amounts contributing to the exposure on the two portions of the photosensitive member during the flash light photographing, are worked out in the APEX system.
Hereinbelow, the process how the data in the APEX system contributing to the exposure are obtained by the equations (9-1) and (9-2) will be explained.
Upon elimination of Qvf1 and Qvf2 from the equations (2-1) and (2-2) through employment of the equations (8-1) and (8-2), equations as follows are obtained.
and by taking the logarithm of both sides of these equations to the base of two, respectively, the equations (9-1) and (9-2) are contained. Meanwhile, as is clear from the equations (9-1) and (9-2), the data log.sub.2 (2.sup..DELTA.L1 +1) andlog.sub.2 (2.sup..DELTA.L2 +1) from the ROM 31 and 32 are equivalent to the ratio of light amounts contributing to the exposure of the respective portions when the flash light emitting device FL is fired and when the same is not fired, or to thedifference in the APEX system, which is referred to as step number difference .DELTA.d, and represented by
To the addition circuit 35, the data Qvt1 and Qvt2 from the addition circuits 33 and 34 are applied for working out the data Qvt1+Qvt2, which data are further applied to the division circuit 36 for the calculation of
The value Qvt is an arithmetical average of the light amounts at the two portions in the APEX system, and is equivalent to a geometrical average of the light amounts 2.sup.Qvt1 and 2.sup.Qvt2 represented by
which may be regarded as a density average (i.e. the average of the density of particles for the photosensitive member such as a photographic film) when attention is directed to images to be reproduced on the photosensitive member.
To the subtraction circuit 37, the data Qvt1 and Qvt2 from the addition circuits 33 and 34 are applied for the calculation of an equation
the result of which is equivalent to the contrast for the two portions. Meanwhile, in the subtraction circuit 38, calculation is effected based on the data QVT from the division circuit 36 and the data Qvt1 from the addition circuit 33 forworking out an equation
the data of which are equivalent to the ratio of the average light amount to the light amount of a first portion or a difference between the average density and the density of the first portion, i.e. contrast.
In the subtraction circuit 39, calculation is similarly effected for working out an equation
which is equivalent to the contrast between the average and a second portion.
As is seen from the foregoing description, according to the embodiment of FIG. 1, the contrast for the two portions in a scene to be photographed during the flash light emission and that between the average and each of the portions may beobtained. Further, since any alteration of the setting of Tvs .DELTA.f also alters the contrast to be worked out, by altering these set values, exposure factor for achieving the desired contrast may consequently be obtained by means of altering the setvalues till the desired contrast is worked out. It is to be noted here that, although a block for a display or indication device is omitted in FIG. 1, the contrast to be worked out and various data available in the process of calculating the contrastmay be input to the display device for indication.
On the other hand, description will be given hereinbelow with reference to the case where the light measuring calculation is effected without firing the flash light emitting device FL. In the above case, the output data of the subtractioncircuits 17 and 18 become 0 as in the following equations.
In this case, it is so arranged that the data equivalent to -.infin. (minus infinity) are produced from the ROM 19 and 20, and the data are applied to the ROM 31 and 32 without being affected by the calculations in the subtraction circuits 24and 25, and 29 and 30. In the actual practice, it may be so arranged, for example, that the bit unnecessary for effecting the calculation is rendered to be "1" and that, when the data are applied to the ROM 31 and 32, data corresponding to 0 are outputfrom the ROM 31 and 32, irrespective of data by other bits, and thus, the outputs of the addition circuits 33 and 34 will be represented by
Therefore, the contrast to be worked out becomes the ratio with respect to the brightness due to the ambient light, and is not varied even when the set value is altered. Meanwhile, the fact that Qvf1 and Qvf2 are -.infin. means that the flashlight emitting amount is 0, and that the lighting contrast is -.infin., with the step number difference being of 0.
In the embodiment of FIG. 1, the measuring portions by the photoelectric elements P1 and P2 of the two light measuring circuits 1 and 2 have only to be respectively different portions in the scene to be photographed, and therefore, it may be soarranged, for example, that one of the photoelectric elements P1 and P2 measures light at the central portion of the scene, while the other measures the average value at the remaining portion, or that one of the elements P1 and P2 measures light at apart in the upper portion of the scene to be photographed, while the other measures light at a part in the lower portion thereof. The arrangements as described above may further be modified in various ways.
Reference is made to FIG. 2 showing a modified circuit arrangement for obtaining an average light amount according to the present invention. The modification of FIG. 2 is intended to obtain a weighted average, and is particularly effective, forexample, for a light measuring system of a type in which one photoelectric element is arranged to measure light at the central portion of the scene to be photographed, while the other photoelectric element measures the average light intensity in theother portions.
The principle for the above modification will be described hereinbelow. In this case, the average light amount will be represented by
The above equation (13) may be transformed as follows through utilization of the relations log2 0.8.apprxeq.-0.3 and log2 1.8.apprxeq.0.8
On the supposition that
the following relation may be obtain
Accordingly, the data for Qvt2-0.3 are obtained by the subtraction circuit 40 which is connected to the addition circuit 34, and further coupled to a subtraction circuit 41 and an addition circuit 43, while in the subtraction circuit 41, the datarepresented by
are obtained. The above data .alpha. are converted into the data for log.sub.2 (2.sup..alpha. +1) by a ROM 42 connected to the circuit 41, and
is worked out in the addition circuit 43, and further, equations as follows are worked out by a subtraction circuit 44 connected to the addition circuit 43. ##EQU1##
Thus, the value for the weighted average of the light amount in the APEX system may be regarded as obtained.
Reference is also made to FIG. 3 showing another modified arrangement for obtaining the value for the average light amount in the APEX system. This modification intended to obtain a harmonic average is suitable, for example, for a lightmeasuring system of a type in which one photoelectric element mainly measures light at a portion or whole part in the upper section, while the other photoelectric element mainly measures light at a portion or whole part in the lower section of the sceneto be photographed.
The principle for the arrangement of FIG. 3 will be explained as follows.
The harmonic average is represented by
which may be transformed as
Therefore, upon employment of the relation
the relation as follows may be established
Accordingly, in FIG. 3, the calculation of the equation (12-1) is effected in the subtraction circuit 37 for working out the data for .DELTA.c21, which data are converted into the data for log.sub.2 (2.sup..DELTA.c21 +1) by a ROM 46. Based onthe above data and the data Qvt2 from the addition circuit 34, a subtraction circuit 47 coupled to the circuit 34 works out
and since 1 is added to the above data by an addition circuit 48 connected to the circuit 47, the result of the following equations are obtained, ##EQU2## and thus, the value in the APEX system of the average light amount on the harmonic averagemay be regarded as obtained.
Referring further to FIG. 4 showing a block diagram for working out aperture values to achieve optimum exposures or proper exposures based on the light amounts for the two portions and the average light amount as obtained in the arrangements ofFIG. 1, FIG. 2 or FIG. 3, the addition circuits 33 and 34 are coupled to a block 50 which is equivalent to the blocks 35 and 36 of FIG. 1 or to the block producing the average light amount Qvt of the arrangement of FIG. 2 or FIG. 3 and which is furthercoupled to an addition circuit 53. The circuits 33 and 34 also connected to addition circuits 51 and 52, while a film speed output circuit 49 for producing data for the film speed Sv is further connected to the addition circuits 51 and 52 and also tothe addition circuit 53.
To the addition circuit 51, the data Qvt1 from the addition circuit 33 and the data Sv from the film speed output circuit 49 are applied for the calculation of an equation
which represents the APEX value of the aperture value for achieving the optimum exposure at the first portion. Moreover, in the addition circuit 52, the relation
is worked out based on the data Qvt2 from the addition circuit 34 and the data Sv from the film speed output circuit 49. The resultant value is the aperture value in the APEX system for obtaining the optimum exposure at the second portion. Furthermore, in the addition circuit 53, the relation
is calculated based on the data Qvt from the average value calculation block 50 and the data Sv from the film speed output circuit 49. The resultant value is the aperture value in the APEX system for achieving the optimum exposure on the wholescene to be photographed.
Referring to FIG. 5 schematically showing an optical system of a light measuring meter to which the present invention is applied, and also to FIG. 6 showing, on an enlarged scale, a light receiving portion of each of photoelectric elements, theoptical system of FIG. 5 includes an objective lens 60, a half-mirror 61 for dividing light so disposed in the optical axis of the lens 60 as to lead one portion of the divided light towards photoelectric elements PD1 to PD5 and the other portion thereoftowards a finder system through a condenser lens 62, a focusing screen 63, a pentagonal roof prism 64 and an eye piece 65, while index marks 631, 632, 633, 634 and 635 are disposed on the focusing screen 63 for informing an observer of light measuringportions or spots P1, P2, P3, P4 and P5 (FIG. 6). By the employment of the optical system as described above, five portions or spots in the scene to be photographed surrounded by solid lines in FIG. 6, i.e. the central portion P1, upper left portion P2,upper right portion P3, lower left portion P4 and lower right portion P5 may be subjected to the spot light measurements.
Referring also to FIG. 7 showing a general appearance of the light measuring meter applied with the present invention, functions of respective operating portions and a display portion DI thereof will be described hereinbelow.
The light measuring meter of FIG. 7 has a hot shoe HS provided at its top portion for mounting a flash light emitting device such as an electronic flash (not shown here), a terminal ST for a trigger cord of the flash light emitting deviceprovided adjacent to the bottom edge, a key or push button MK for light measuring provided at the front edge thereof and arranged, upon depression, to start firing or light emission of the flash light emitting device and also the light measurement, anexposure time setting key TK provided at one side face of the meter and so arranged that, when depressed simultaneously with an up key UK or a down key DK provided side by side on the same one side face of said meter, the set exposure time indicated in adisplay portion DI2 of a display section DI starts varying in a unit of one Ev for each predetermined period of time until the set exposure time reaches a limit value, an ASA sensitivity setting key ASK provided next to the exposure time setting key TKand so arranged that, when being depressed simultaneously with the up key UK or down key DK, the ASA sensitivity displayed in a display portion DI3 is varied at a step of 1/3Ev, and another key .DELTA.K for setting the change in guide number of the flashlight emitting device, provided next to the key ADK and adapted, when being depressed simultaneously with the up key UK or down key DK, the set value displayed in a display portion DI4 is varied at a step of 0.5 Ev. With respect to the setting of theASA sensitivies and alteration amounts also, the data stop varying upon reaching of the set value to the limit value. It is to be noted that the up key UK is depressed for increasing the APEX value of the set data, while the down key DK is depressed forreducing the same.
The light measuring meter of FIG. 7 further includes a contrast key CK provided below the key TK and arranged, when depressed, to indicate an indication "CONT" among the indications "CONT", "L.CONT", "F.NO", "FLASH" and "AMBI" for a displayportion DI5, and also, to indicate in display portions DI6 and DI7, numbers showing the two spots, with further indication of the contrast value as worked out based on the measured value in a display portion DI1 in a unit of 0.1 Ev, a lighting contrastkey LCK provided next to the key CK and adapted, when depressed, to display "L.CONT" in the display portion DI5 and number of the light measuring portions in the display portion DI6, without any indication in a display portion DI7, but with indication ofthe worked out lighting contrast value in the display portion DI1.
Further included in the light measuring meter of FIG. 7 are an F No. key FNK, a F/B key FBK, and a key AVK which are aligned with the keys CK and LCK, and keys 1K, 2K, 3K, 4K and 5K provided in a line below the keys CK, LCK, FNK, FBK and AVK, anda slide switch FAS provided at the right side of the above keys in FIG. 7.
Upon depression of the F No. key FNK, the number of the light measuring spot is displayed in the display portion DI6, and the display portion DI7 is kept blank, while the display portion DI1 displays the F number, with the value less than 0.1 Evbeing indicated in a unit of 0.1 Ev. Meanwhile, upon depression of the F/B key FBK, when the slide switch FAS is at the side FLASH, the display portion DI5 indicates "FLASH", and the display portion DI6 indicates the number of the measuring spot, withthe display portion DI7 kept blank, while the display portion DI1 displays the reflected light amount due to firing of the flash light emitting device upon photographing in the value of the APEX system. On the other hand, when the slide switch FAS isset to the AMBI side, the display portion DI5 displays "AMBI", and the display portion DI1 indicates the scene brightness, while the display portion DI6 shows the number of the measuring spot, with the display portion DI7 kept blank. The keys AVK and 1Kto 5K are intended to designate the light measuring position of the measured value to be indicated in the display portion DI1, and the key AVK designates the average value of the five light measuring spots, while the key 1K designates the spot P1, key 2Kthe spot P2, key 3K the spot P3, key 4K the spot P4, and key 5K the spot P5, respectively.
Hereinbelow, operation of the light measuring meter of FIG. 7 will be described.
Upon depression of the light measuring key MK, the flash light emitting device is fired for effecting the light measuring, and subsequently, calculation is carried out by taking-in the measured value. The set values are displayed in the displayportions DI2, DI3 and DI4, while the display mode is indicated in the display portion DI5, with the calculated value being displayed at the portion DI1. In the case of the contrast display, the measuring spots are indicated by the portions DI6 and DI7,while in the cases other than the contrast display, the measuring spots are indicated only by the display portion DI6. For the average value, the indication is given in the form of " ".
If the key operation is not made for a predetermined period of time after effecting the indication, all the indications of the display section DI are automatically erased. Meanwhile, when any one of the keys TK, ASK and .DELTA.K, and the key UKor DK are depressed, the set value is altered together with the alteration of the indicated value at the display portion DI1. After a predetermined period of time from the above key operation, all the indications at the section DI are erased. If thelight measuring key MK is kept depressed, the measured value based on the ambient light is continuously taken-in, and the indicated value at the display portion DI1 is varied, following the variation of the scene brighness. On the other hand, when thekey CK, LCK, FNK, or FBK is actuated for changing over the mode, or the keys AVK, or 1K to 5K are operated for changing over the measuring points, the contents of indications are also changed over, and if the key operations are not effected by apredetermined period of time, all the indications are erased. In the case where the light measuring is effected without using the flash light emitting device, indications based only on the ambient light are effected.
Reference is also made to FIG. 8 showing an electrical circuit diagram of the light measuring meter of FIG. 7, which generally includes a circuit portion surround by dotted lines and having a light measuring circuit 80 coupled to an A-D converter82 through a multiplexer 81 so as to be supplied with power from a power source battery E through the emitter-collector circuit of a transistor BT1, and a micro-computer 100 (referred to as .mu.-com hereinbelow) whose output terminal OT2 is connected tothe base of the transistor BT1 through an inverter IN1 and a suitable resistor, so that the power feeding transistor BT1 is controlled through the output terminal OT2 of the .mu.-com 100 and the inverter IN1.
Referring also to FIG. 9 showing specific circuit constructions of the light measuring circuit 80 and multiplexer 81 in FIG. 8, photoelectric elements PD1 to PD5 corresponding to the light measuring portions P1 to P5 are respectively coupled,through diodes D1 to D5 for the logarithmic compression, to operational amplifiers OA1 to OA5 whose output terminals produce potentials corresponding to the logarithmically compressed value of light intensities received by the photoelectric elements PD1to PD5 and are coupled to the bases of transistors BT11 to BT15 for logarithmic expansion through field effect transistors or FET FT21 to FT25 for analog switches, while the transistors BT11 to BT15 whose collectors are respectively connected to thebases of current mirror transistors BT21 to BT25 are further coupled to known circuits composed of diodes D11 to D15 and D21 to D25 and capacitors C11 to C15, etc. disclosed, for example, in Japanese Patent Publication Tokkosho No. 50-28038 and arrangedto produce voltages obtained by subjecting the integrated values of currents flowing thereinto, at opposite sides of said capacitors C11 to C15, to which FET FT31 to FT35 are connected for resetting said capacitors. The output terminals of theoperational amplifiers OA1 to OA5 are further coupled to analog switches of FET FT61 to FT65 through analog switches of FET FT11 to FT15 and through analog switches FET FT41 to FT45, FT11 to FT15 constitute sample-and-hold circuits in combination withcapacitors C21 to C25 connected thereto, respectively. FET FT51 to FT55 respectively connected to lines leading to the circuits including the diodes D11 to D15, and D21 to D25 and capacitors C11 to C15, the FET FT61 to FT65 for analog switches describedearlier and a decoder DE, constitute the multiplexer 81 in FIG. 8. Based on the data from the output port OP1 of the .mu.-com 100, the decoder DE renders any one of its output terminal d1 to d10 to be "High" so as to turn ON corresponding one of the FETFT51 to FT55, and FT61 to FT65 for applying an analog signal from one of the capacitors C11 to C15 and C21 and C25 to the A-D converter 82.
The relationship between the data for the output port OP1 of the .mu.-com 100 and input data are shown in Table 1 below
TABLE 1 ______________________________________ Output port "High" terminal FET turned OP1 of decoder ON Input data ______________________________________ 0110 d1 FT51 Qv1 0111 d2 FT52 Qv2 1000 d3 FT53 Qv3 1001 d4 FT54 Qv4 1010 d5 FT55Qv5 1011 d6 FT61 Bv1 1100 d7 FT62 Bv2 1101 d8 FT63 Bv3 1110 d9 FT64 Bv4 1111 d10 FT65 Bv5 ______________________________________
Referring back to FIG. 8, the .mu.-com 100 of a single chip type includes a power on/clear circuit 101, a clock generator 102, a RAM 103, an address controller 104 for the RAM 103, an accumulator 105, a carry flag 106, an ALU 107, a divider 108,a ROM 110, an address controller 109 for the ROM 110, an input flip-flop IF1, input ports INP1 and INP2, and output ports OUP1, OUP2 and OUP3, etc. The features of the above .mu.-com 100 are such that, when power is first supplied to the .mu.-com 100following replacement of the power source battery E and the like, functioning is started from the particular address of the ROM 110 through actuation of the power on/clear circuit 101. Meanwhile, under the state of clock end or CEND, instructions arenot executed, and the clock generator 102 and divider 108 start functioning, for executing the instruction from the particular address of the ROM 110, upon receipt of one second (sec.) signal from the divider 108 or of any key input. For the .mu.-com100 as described above, for example, a model SM-4 (trade mark) micro-computer sold by Sharp Corporation, Japan may be suitably employed.
Subsequently, the functions of respectively labelled registers and flags in the RAM 103 will be described hereinbelow, which include a flag SFJ for judgement as to whether or not the firing signal for the flash light emitting device should beproduced, a flag IFJ for determining the completion of the reception of all light measuring data, a flag MCJ for determining whether or not the light measuring is being effected, a flag DFJ for determining whether or not the calculation for indicationdata is completed, and a flag QJF for determining whether or not the reflected flash light amount Qvfm caused by the flash light emitting device firing upon the light measuring is worked out, and a register DIR for selection of taken-in data, thecontents of which register DIR are produced from the output port OP1. The relation between the contents of the register DIR and taken-in data is shown in Table 1'.
There are further provided a register COR for counting the time from the termination of the key operation to the de-energization of the display, a register DSR in which the data of .DELTA.f is set, a register TVR in which the set exposure timeTvs is set, a register SVR in which the specific film speed is set and a register BDR in which the data corresponding to the display mode are set. The relation of the contents and display modes for the register BDR is shown in Table 2.
TABLE 1' ______________________________________ DIR Data ______________________________________ 0110 Qv1 0111 Qv2 1000 Qv3 1001 Qv4 1010 Qv5 1011 Bv1 1100 Bv2 1101 Bv3 1110 Bv4 1111 Bv5 ______________________________________
NDR1 and NDR2 are registers in which data indicating the light measuring portions corresponding to the light measuring spots P1 to P5 and the average are set, and in the cases other than "contrast", the portion corresponding to the content of theregister NDR1 is set as the light measuring portion. Meanwhile, in the case of "contrast", this will be the contrast between the portions corresponding to the contents of the registers NDR1 and NDR2. The relations between the contents of the registersNDR1 and NDR2, and the light measuring portions are shown in Table 3 below.
TABLE 2 ______________________________________ BDR Display mode (display contents) ______________________________________ 0001 Contrast (CO) 0010 Lighting contrast (LC) 0100 Aperture value (F No.) (F) 1000 Reflected light amount caused byonly flash (Qvt) light emitting device upon photographing 1001 Brightness due to ambient light (Bv) ______________________________________
TABLE 3 ______________________________________ NDR1 NDR2 Light measuring portion ______________________________________ 0001 P1 0010 P2 0011 P3 0100 P4 0101 P5 0110 Average ______________________________________
DPR1 is a register in which display data for the display portion DI1 are set, DPR2 is a register in which data obtained by decoding the content of the register BDR, i.e. display data for the display portion DI5 are set, DPR3 is a register inwhich data obtained by decoding the content of the register NDR1, i.e. display data for the display portion DI6 are set, and DPR4 is a register in which data obtained by decoding the content of the register NDR2, i.e. display data for the display portionDI7 are set, DPR5 is a register in which data obtained by decoding the content of the register TVR are set, which data are output from an output port OP3, DPR6 is a register in which data obtained by decoding the contents of a register SVR are set, whichdata are output from an output port OP4, and DPR7 is a register in which data obtained by decoding the contents of the register DFR are set, and the content thereof is output from an output port OP5. Registers QVR1 to QVR5, and BVR1 and BVR5 are theregisters in which the light measuring data taken-in from the A-D converter 82 are set, and data Qv1 are set in the register QVR1, data Qv2 in the register QVR2, data Qv5 in the register QVR5, data Bv1 in the register BVR1, data Bv4 in the register BVR4,and data Bv5 in the register BVR5. Registers OFR1 to OFR5, and QFRA are the registers in which the reflected light amounts caused by only the flash light emitting device during the light measuring are set, and data Ovfm1 are set in the register QFR1,data Qvfm2 in the register QFR2, data Qvfm5 in the register QFR5, and data Qvfm in the register QFRA. Furthermore, in the RAM 103, there are provided a register for calculation, and registers for temporarily memorizing other data, etc., although notparticularly shown.
Still referring to FIG. 8, the output terminal OT1 of the output port OUP1 coupled to the A-D converter 82 feeds an A-D conversion starting signal for the A-D converter 82, while the output terminal OT2 thereof connected to the base of thetransistor BT1 through the inverter IN1 and suitable resistance for providing a power feed signal for the circuit portion surrounded by the dotted lines in FIG. 8, furthermore the output terminal OT2 thereof connected to an input terminal of a one shotcircuit OS, for providing the reset signals for the integrating capacitors C11 to C15. The terminal OT3 of the output port OUP1 is connected to the light measuring circuit 80 directly, and also to said light measuring circuit 80 through an inverter IN2,and further to a trigger circuit 83 of the flash light emitting device so as to supply a change-over signal between the integration during flash light emission and light measuring of the ambient light, and the flash light emitting signal. Meanwhile, theterminal OT4 is connected to the light measuring circuit 80 for providing the sample-and-hold.
From the output port OUP2, the content of the take-in data selection register DIR is output as decribed earlier. The data for the display are produced from output terminals OP2 and OP3 of the output port OUP3, while a strobe signal for thedisplay and key scanning is developed from the output terminal OP9 thereof. There are further provided the input port INP1 for taking-in the digital data from the A-D converter 82 and another input port INP2 to which the key signal is applied.
The relations between the key switches of FIG. 8 and the key buttons in FIG. 7 are such that, the switch TS corresponds to the key TK, the switch ASS to the key ASK, the switch US to the key UK, the switch DS to the key DK, the switch CS to thekey CK, the switch LCS to the key LCK, the switch FNS to the key FNK, the switch FBS to the key FBK, the switch 1S to the key 1K, the switch 2S to the key 2K, the switch 3S to the key 3K, the switch 4S to the key 4K, the switch 5S to the key 5K, theswitch AVS to the key AVK, the switch MS to the key MK, and the switch .DELTA.S to the key .DELTA.K, respectively. The switch FAS' is associated with the slide switch FAS in FIG. 7, and arranged to be connected to a terminal FL at the "FLASH" side, andto a terminal AM at the "AMBI" side.
FIGS. 10(A), 10(B), 11(A), 11(B), 12(A), 12(B), and 12(C), and FIGS. 13 and 14 are flow charts showing functioning of the .mu.-com 100, on the basis of which functions of the circuit arrangement of FIGS. 8 and 9 will be explained hereinbelow.
In the flow charts of FIGS. 10(A) and 10(B) illustrating the overall functioning, upon input of a 1 sec. signal or key signal in the CEND state, the .mu.-com 100 starts functioning according to the instruction from the particular address of theROM 110. In a step #1, judgement is made as to whether the signal is the 1 sec. signal or key signal, and in the case of the 1 sec. signal, 1 sec. function as shown in FIG. 13 is effected. Meanwhile, in the case of the key signal, judgement is made asto whether or not the light measuring switch MS is "ON". If the light measuring switch MS is not "ON", the operation of the .mu.-com 100 is shifted to a step #5 after effecting the key judging function as shown in FIGS. 12(A), 12(B) and 12(C). On thecontrary, if the light measuring switch MS is ON, the terminal OT2 is rendered to be "High", and then, "High" pulses are produced from the one shot circuit OS for a predetermined period of time for turning ON the FET FT31 to FT35 and resetting thecapacitors C11 to C15. Simultaneously, the output of the inverter IN1 is rendered to be "Low", and thus, the transistor BT1 starts feeding the power. In the above case, since the output terminal OT3 is "Low", the FET FT21 to FT25 are rendered to benon-conductive, without charging of the capacitors C11 to C15.
At a step #4, "1" is set in the light emission judging flag SFJ, while "0" is set in each of the data take-in judging flag IFJ, light measuring state judging flag MCJ, display data completion judging flag DFJ, and Qvfm calculation completionjudging flag QJF. Subsequently, at the step #5, judgement is to be made as to whether or not the take-in of the display data is completed, but since the take-in is not finished yet at the time point when the light measuring switch MS is depressed, theoperation of the .mu.-com 100 is shifted to a step #6 so as to judge whether or not the calculation of the data for display is completed. If the calculation of the display data is not finished, data for "blank" (i.e. data for cancelling the display) areset in the display registers DPR1 to DPR7 at a step #7, and judgement is made as to whether or not the flash light is to be subsequently emitted. When the light measuring switch MS is closed, it is necessary to fire the flash light emitting device, andthe operation of the .mu.-com 100 is shifted to a step #9 so as to render the terminal OT3 to be "High", so that the trigger signal for the flash light emitting device is developed from the trigger circuit 83, while, at the same time, the FET FT11 toFT15 are rendered to be non-conductive, and FT21 to FT25 are rendered conductive in FIG. 9, and thus, charging of the capacitors C11 to C15 is started. After setting "0" in the light emission judging flag SFJ through counting of a predetermined periodof time T1, the terminal OT3 is again rendered to be "Low", whereby the FET FT21 to FT25 are rendered to be non-conductive, with the charging of the capacitors C11 to C15 being suspended to sample and hold the integrated value at this time.
The time period required from the step #3 to the step #9 is arranged to be longer than the time period from starting of the power supply to the light measuring circuit 80 up to the stabilization of said circuit. Meanwhile, the time periodrequired from the step #9 to the step #12 is adapted to be longer than the time period required for the ordinary flash light emitting device to fully fire, and is equivalent to Tvc in the APEX value.
In a step #13, the terminal OT4 is rendered to be "High", with the transistors FT41 to FT45 in FIG. 9 turned ON for counting a predetermined time T2. Subsequently, at a step #15, the output terminal OT4 is again rendered to be "Low" so as toturn OFF the FET FT41 to FT45. Therefore, outputs of the operational amplifiers OA1 to OA5 are sampled and held in the capacitors C21 to C25.
At a step #16, judgement is made as to whether or not this step is reached by the closing of the light measuring switch MS, and when this step is reached by the key judging function as described later, the operation of the .mu.-com 100 is jumpedover to a step #20.
In a step #17, the content of the take-in data designation register DIR is developed from the output port OP1, and fed to the multiplexer 81. At the time point when the light measuring switch MS is depressed, the content of the register DIR isat 0110 as mentioned later, and the decoder DE in FIG. 9 renders the terminal d1 thereof to be "High" for conduction of the FET FT51, and the integrated voltage Qv1 of the capacitor C11 is input to the A-D converter 82. In steps #18 and #19, pulses of"High" are produced from the terminal OT1 to start the converting function of the A-D converter 82, and at a step #20, the contents of the registers DPR1 to DRP7 for the display are output to the output ports OP2 to OP8. In the above case, if the keyjudging function described later or calculation of the display data has been completed, predetermined indications are effected in the display portions DI1 to DI7, and when this step has been reached through the step #7, nothing is displayed in thedisplay portions DI1 to DI7. It is to be noted that the output ports OP2 to OP7 have latch functions and maintain the existing output data until such data are altered.
In a step #21, judgement is made as to whether or not the light measuring is under way, and if not, the operation of the .mu.-com 100 is shifted to a step #28 so as to reset the register for the display time counting and the .mu.-com 100 becomesthe CEND state. If it is judged in the step #21 that the light measuring is under way, the data from the A-D converter 82 are taken-in from the input port IP1. The time period required from the step #18 to a step #22 is arranged to be longer than atime period required for the A-D conversion.
Subsequently, in a step #23, it is judged whether or not the light measuring switch MS is closed, and if not, judgement is further made as to whether or not the data take-in has been completed at a step #24. If the data take-in has beenfinished, the terminal OT2 is rendered to be "Low", with the power feeding transistor BT1 turned OFF, and "0" is set in the light measuring proceeding judging flag MCJ, while the data 0110 designated Qv1 are set in the take-in data selecting registerDIR, and the counter register COR is reset and the .mu.-com 100 becomes the CEND state.
If the light measuring switch MS is closed or data have not been taken-in at a step #23 or #24, the operation of the .mu.-com 100 is shifted to a step #29. In the step #29, the content of the register DIR is judged, on the basis of which thedata taken-in are set in the register corresponding to said data. More specifically, if the content of the register DIR is 0110, the data are of Qv1 and set in the register QVR1, and if 1001, the data are of Qv4 and set in the register QVR4, and if1101, the data are of Bv3 and set in the register BVR3, while if 1111, the data are Bv5 which are set in the register BVR5. Meanwhile, the contents of the register DIR increases by one at a step #31. And a judgement is made as to whether or not thecarry flag 106 is rendered to be "1" at a next step #32 (i.e. whether or not the result of the calculation has become 10000), and if it is not of "1", "0" is set in the take-in judging flag IFJ, and the operation of the .mu.-com 100 is shifted to a step#5 in FIG. 10(A). When the carry flag 106 has become "1", it may be regarded that the content of the register DIR before the addition at a step #30 was 1111, and thus, taking-in of ten data has been completed. Accordingly, "1" is set in the take-incompletion judging flag IFJ, with subsequent setting of 1011 in the register DIR, and at steps #36 to #38, the outputs of the operational amplifiers OA1 to OA5 in FIG. 9 are sampled and held on the capacitors C21 to C25, and the operation of the .mu.-com100 is returned to the step #5.
The taking-in of the light measuring data will be described again more in detail hereinbelow.
Upon closing of the light measuring switch MS, the flash light is emitted, at a first time, for effecting the integrating function, and the light measuring value of the ambient light is successively sample and held. Subsequently, the content0110 of the register DIR is output to take-in the data Qv1 through A-D conversion for setting in the register QVR1. Then, "1" is added to 0110, which data are output so as to subject the data Qv2 to A-D conversion for setting in the register QVR2, andby the addition of "1" to 0111, similar functioning as described earlier is subsequently repeated, and when the result of calculation for adding "1" to the register DIR is overflowed (carry is "1"), taking-in of all the data has been completed. Thereafter, the light measuring value of the ambient light is again sampled and held so as to follow the variation of the ambient light, while 1011 is set in the register DIR so that only the data of the ambient light are subsequently taken-in.
Then, the operation of the .mu.-com 100 is reverted to the step #5, and after effecting the calculation as shown in FIGS. 11(A) and 11(B), the data Bv1 are again subjected to A-D conversion, with the calculated value being indicated for taking-inthe data for Bv1, and if the light measuring switch MS is open at this time, the state of CEND is established through the steps subsequent to the step #24. In the case where the light measuring switch MS has been closed in the above case, the datataken-in are set in the register BVR1, with "1" added to the register DIR, and the register IFJ is further rendered to be "0" and the operation of the .mu.-com 100 is returned to the step #5, and thereafter, functionings similar to those describedearlier are repeated. Accordingly, if the light measuring switch MS has been opened at the time point when the first data taking-in is completed, calculations and indications are effected based on the take-in data at this time. Meanwhile, if the lightmeasuring switch MS remains closed, the display also remains as before until the second taking-in of the light measuring value based on the ambient light has been completed, and upon completion thereof, the calculations and display of the second data areeffected again. Meanwhile, when the first data take-in loop is started, the taking-in is repeated until the data have been completely taken-in, even if the light measuring switch MS is opened during such time period, and at the time point where thetaking-in has been completed, the state of CEND is established.
Referring also to FIGS. 11(A) and 11(B) showing the flow charts for the calculation functions illustrated in FIG. 10(A), at a step #41, judgement is made as to whether or not the calculation of the light emitting amount Qvfm only for the flashlight emitting device during the light measuring period has been completed. Since the calculation is not yet finished at the time point where the first data taking-in has been completed, the operation of the .mu.-com 100 is shifted to a step #42, and ifthe step #41 is reached, upon completion of the data taking-in subsequent to the second time or by the key judging function, the operation of the .mu.-com 100 is shifted to a step #45. At the step #42, calculations as follows are effected.
The light measuring data set in the registers QVR1 to QVR5 are represented by ##EQU3##
Therefore, based on the above data, the data of the registers BVR1 to BVR5 and the fixed data Tvc, equations as follows are calculated. ##EQU4##
The data .DELTA.11 to .DELTA.15 thus worked out are converted into data for log.sub.2 (2.sup..DELTA.11 -1).about.log.sub.2 (2.sup..DELTA.15 -1), and by adding these data to the data of (Bv1-Tvc).about.(Bv5-Tvc), the following equations are workedout. ##EQU5##
At a step #43, the data for the average value Qvfm are obtained, based on the data Qvfm1 to Qvfm5 worked out at the step #42. In this embodiment, description will be made with reference to the case of the weighted average, with the weighting ofthe light measuring value at the portion P1 being set to be 1 and that at the portions P2 to P5 set to be 0.4. Accordingly, the light measuring in this case is equivalent to the center-weighted averaged light measurement. The average value Qvfm isrepresented by ##EQU6## where the relations log.sub.2 0.4=-1.3, log.sub.2 2.6=0.7 are utilized.
Subsequently, the equation
is worked out and transformed into log.sub.2 (2.sup..alpha.1 +1) for the calculation of
and the data Qvfm12 in the relation as follows are obtained.
Thereafter, the equation
is calculated and transformed into log.sub.2 (2.sup..alpha.2 +1) for the calculation of
and the data Qvfm13 in the relation as follows are worked out.
Subsequently, in the similar manner as above, the data Qvfm15 in the following relations are obtained.
Upon subtraction of 0.7 from the above data, the value Qvfm is obtained as is clear from the equation (16-2).
Meanwhile, when the light measurement is effected without firing the flash light emitting device or the object to be measured for the light intensity is located at a long distance, or the reflected light flash amount is extremely small ascompared with the light amount of the ambient light, the reflected light amount 2.sup.Qvfm by the flash light during the light measurement undesirably becomes 0 as represented by
In the above case, the value Qvfm become -.infin., but when the data .DELTA.11 to .DELTA.15 become the data corresponding to values less than predetermined values (for example 0.1), data corresponding to -.infin. are set in the register wherethe value Qvfm is to be set. Furthermore, even in the process of calculating the average value Qvfm, if .alpha. becomes the data corresponding to the value less than the predetermined value (for example -3.8), the minuend is arranged to be output as itis. More specifically, for example, in the relation .alpha.2.ltoreq.-3.8, the data are so arranged that Qvfm12=Qvfm13. Similarly, for example, when Qvfm2 is of data corresponding to -.infin., the relation is so arranged as Qvfm1=Qvfm12.
In the step #45, based on the data .DELTA.f in the register DFR and the calculated data Qvfm1 to Qvfm5 and Qvfm, the equations as follows are calculated so as to work out the reflected flash light amounts Qvf1 to Qvf5 and Qvf of the flash lightduring photographing ##EQU7##
In the above case also, when the data Qvfm are corresponding to -.infin., the data Qvf are arranged to remain as corresponding to -.infin.. Subsequently, at a step #46, the average value Bv is obtained based on the light measuring data Bv1 toBv5 taken-in the registers BVR1 to BVR5. In this case, the average value Bv is represented by the following relation in the similar manner as in the average value Qvfm, and may be worked out in the similar fashion to the calculation in the step #43. ##EQU8##
At a step #47, based on the contents Bv1 to Bv5 of the resisters BVR1 to BVR5, the data Tvs for the exposure time set in the register TVR, and the data Bv calculated in the step #46, calculations are made as follows. ##EQU9##
Subsequently, in a step #48, following calculations are effected for working out the data .DELTA.L1 to .DELTA.La corresponding to the lighting contrast. ##EQU10##
In the above case, if the value Qvf is of the data corresponding to -.infin., .DELTA.L is also set for the data corresponding to -.infin.. Thereafter, the data worked out are converted into data corresponding to log.sub.2 (2.sup..DELTA.L1+1).about.log.sub.2 (2.sup..DELTA.L.alpha. +1), and by adding these data to (Bv1-Tvs).about.(Bv5-Tvs), calculations as follows are effected. ##EQU11##
In other words, it may be regarded that the light amount owing to the ambient light during the photographing and flash light has been worked out. In the above case, when the value .DELTA.L is of the data corresponding to those less than thepredetermined value (for example -3.8) or of the data corresponding to -.infin., the relation is as follows.
Subsequently, in a step #49, the average value Qvt is worked out based on the data Qvt1 to Qvt5 calculated at the step #48. The value Qvt is represented by ##EQU12## I
The above calculation is effected in the similar manner as in the steps #43 and #46.
In a step #50, it is judged whether or not the content of the display mode judging register BDR is "1". If it is "1", the mode is for displaying the contrast.
Meanwhile, at a step #51, data Qvt corresponding to the register NDR2 are subtracted from the data Qvt corresponding to the register NDR1 in which the data corresponding to the light measuring portion are set, and thus, the contrast between thelight measuring portion corresponding to the data of the register NDR1 and that corresponding to the data of the register NDR2 is worked out as follows.
The data .DELTA.C (represented by COD in the flow chart) thus worked out are converted into data for display so as to be set in the register DPR1 and further, the data of the register NDR2 are also decoded and set in the register DPR4.
In the case where the data for the register BDR are not of "1" in the step #50, it is judged whether or not the register BDR is of "2" at a step #54. If it is of "2", the mode is for the display of lighting contrast as shown in Table 2. In astep #55, based on the lighting contrast .DELTA.L obtained in the calculation at the step #48, the data for the lighting contrast (represented by LCD (NDR1) in the flow chart) of the light measuring portion corresponding to the content of the registerNDR1 are decoded into the display data for setting in the register DPR1. In the above case, when the data for the lighting contrast .DELTA.L correspond to -.infin., display data by which, for example, the indication -.quadrature..quadrature. iseffected at the display portion DI1, are set in the register DPR1.
In the case where the content of the register BDR is not of "2" in the step #54, judgement is subsequently made in a step #56 as to whether or not the content is of "4". If it is of "4", the mode is for indication of the aperture value whichprovides the optimum exposure. In this case, the equation as follows is worked out, based on the data Qvt (NDR1) of the light amount at the light measuring portion corresponding to the content of the register NDR1 and the film speed Sv set in theregister SVR.
The data thus worked out (represented by AVD in the flow chart) are decoded into the data necessary for indication in F number and set in the register DPR1.
When the content of the register BDR is not of "4" in a step #56, the content is of "8" as is seen from Table 2, which is the mode for displaying the reflected light amount Qvf due to the flash light emitting device firing upon photography or thebrightness Bv due to the ambient light. In a step #59, it is judged whether or not the input flip-flop IF1 is set, with the switch FAS connected to the terminal FL. If the switch FAS is connected to the terminal FL, the data Qvf corresponding to thereflected light amount of the light measuring portion which corresponds to the content of the register NDR1 are decoded into display data for setting in the register DPR1.
In a step #61, since no display is given at the display portion DI7 except for the case of the display mode for contrast, blank data are set in the register DPR4. Meanwhile, in a step #62, the content of the register BDR is decoded so as to beset in the register DPR2, which data serve as the display data for the display portion DI5.
In the case where the input flip-flop IF1 is not set in the step #59, the switch FAS has been connected to the terminal AM, and the mode is for the display of the scene brightness due to the ambient light. In the above case, the content of theregister BDR is made to be "9" through addition of "1" thereto, and simultaneously, the data Bv for the scene brightness at the light measuring portion corresponding to the content of the register NDR1 are decoded so as to be set in the register DPR1,while the content of the register BDR is decoded for setting in the register DPR2, and then, "1" is subtracted from the content of the register BDR, with data for blank being set in the register DPR4, and thus, the operation of the .mu.-com 100 isshifted to a step #68.
In the step #68, the data of the register NDR1 are decoded so as to be set in the register DPR3. In the above case, the data to be set are such that, for the display at the light measuring portions P1 to P5, ordinary indications of 1 to 5 areeffected, while for the indication of the average value, the display " " is made. In a step #69, the data of the register TVR are decoded into data necessary for displaying the exposure time and set in the register DPR5. Furthermore, in a step #70,decoding is effected into data necessary for indicating ASA sensitivity based on the data of the register SVR and set in the register DPR6. In a step #71, decoding is also effected, based on the data of the register DFR, into data necessary fordisplaying .DELTA.f so as to be set in the register DPR7, and subsequently, after setting "1" in the flag DFJ for judging whether or not the setting of the indication data has been completed, the operation of the .mu.-com 100 is shifted to the step # 16(FIG. 10(B)).
The functions related to the flow-charts of FIGS. 11(A) and 11(B) will be summarized as follows.
When the flow is first entered upon effecting the light measurement, the reflected light flash amounts Qvfm1 to Qvfm5 and Qvfm are calculated. Meanwhile, with the light measuring key MS being kept depressed, when the light measuring data Bv1 toBv5 are again taken-in and the operation of the -com 100 has entered this flow, the calculations of the reflected light amounts Qvfm1 to Qvfm5 and Qvfm are not effected, Qvfm of the flash light emitting device are not effected, but calculationssubsequent to the step #45 are performed, based on the data previously worked out. Subsequently, the data Qvf1 to Qvf5, Qvf, Bv, .DELTA.L1 to .DELTA.L5, .DELTA.La, Qvt1 to Qvt5 and Qvt are calculated, and thus, the data corresponding to the set displaymodes are set in the display registers DPR1 to DPR7.
For displaying the contrast, the difference between the data Qvt corresponding to the position which corresponds to the content of the register NDR1 and the data Qvt corresponding to the position which corresponds to the content of the registerNDR2 is displayed at the display portion DI1, and the position corresponding to the register NDR1 is displayed at the display portion DI6, while the position corresponding to the register NDR2 is displayed at the display portion DI7. The display portionDI5 is indicated with "C ON", and the set exposure time is displayed at the display portion DI2, the film speed, at the display portion DI3, and .DELTA.f, at the display portion DI4.
In the case where the lighting contrast is to be displayed, the lighting contrast at the position corresponding to the content of the register NDR1 is displayed at the display portion DI1 in the value of APEX system, and the position whichcorresponds to the content of the register NDR1 is displayed at the display portion DI6, while nothing is displayed at the display portion DI7. Meanwhile, "L.CON" is displayed at the display portion DI5, with set values being displayed at the displayportions DI2 to DI4.
For displaying the data for Qvt, the Qvt at the spot corresponding to the register NDR1 is indicated at the display portion DI1 in the value of the APEX system, and other indications are the same as for the lighting contrast. Meanwhile, in thecase of displaying aperture values for obtaining the optimum exposure, the F number is displayed at the display portion DI1, with "F NO." displayed at the display portion DI5, while other indications are the same as for the lighting contrast. For theindications of the reflected light amount due to the flash light emitting device and the brightness due to the ambient light, the data Qvf and Bv are respectively displayed in the APEX values, with simultaneous indications of "FLA" or "AMB".
It should be noted here that the values to be indicated in the above case need not necessarily be in the APEX system, but the contrast, lighting contrast and .DELTA.f may be arranged to be displayed by the linear system, and that, with respect tothe reflected light amount, it may be so arranged as to work out the equation Qvf+Sv=Avf for displaying the aperture value which provides the proper exposure only by the light emitting amount, or that aperture values corresponding to Ev=Bv+Sv orAv=Bv+Sv-Tv may be arranged to be displayed instead of Bv.
Reference is further made to flow-charts in FIGS. 12(A), 12(B) and 12(C) illustrating the key judging functions.
In the case where the light measuring switch MS is not closed at the step #2 in FIG. 10(A), the operation of the .mu.-com 100 is shifted to a step #80, in which, it is judged whether or not the switch S is closed, and if not closed, the operationof the .mu.-com 100 is further shifted to a step #87, while on the contrary, if the switch .DELTA.S is closed, judgement is made as to whether or not the up switch US is closed. If it is closed, judgement is made as to whether or not the content of the.DELTA.f setting register DSR is at an upper limit, and if at the upper limit, the operation of the .mu.-com 100 is shifted to the step #5, but if the content of the register DSR is not at the upper limit, the data corresponding to 1/2Ev is added to thecontent of the register DSR, and the step is shifted to the step #5. Upon judgement that the up switch US is not closed at the step #81, it is judged whether or not the down switch DS is closed at the step #84. If the above switch DS is closed,judgement is further made as to whether or not the content of the register DSR is at a lower limit, and if it is at the lower limit, the operation of the .mu.-com 100 is shifted to the step #5, while on the contrary, if the content of the register DSR isnot at the lower limit, the operation of the .mu.-com 100 is shifted to the step #5 after subtraction of the data corresponding to 1/2Ev from the content of the register DSR. If it is judged at the step #84 that the switch DS is not closed, either, theoperation of the .mu.-com 100 is moved on to the step #28, and after resetting the display time counting register COR, and the .mu.-com 100 is brought into the CEND state.
Accordingly, if the switches .DELTA.S and US or DS are kept closed during the display of data, .DELTA.f is altered, and data newly worked out based on the altered data are displayed. When both of the above switches are kept closed, the value.DELTA.f is altered at each predetermined period of time, and the calculated value is also altered for the display. Meanwhile, when the two switches are closed during the period not for the display, no display is effected, although the content of theregister DSR is altered.
Steps #87 to #93 relate to the flow of the exposure time setting function, similar to the setting of the value .DELTA.f. In the above case, the content of the register TVR is altered at a unit of 1Ev. Meanwhile, steps #94 to #100 relate to theflow for setting the film speed, similar to the setting of the value .DELTA.f. In this case, the content of the register SVR is altered at a unit of 1/3Ev.
When the film speed setting switch ASS is not kept closed at the step #94, the operation of the .mu.-com 100 is shifted to a step #101. Steps #101 to #108 relate to the flow for the display mode setting, and if the switch CS is kept closed, themode is for displaying the contrast, with 0001 set in the register BDR. When the switch LCS is kept closed, the mode is for displaying the lighting contrast, and 0010 is set in the register BDR. Meanwhile, if the switch FNS is kept closed, the mode isfor displaying the aperture value, with 0100 set in the register BDR, and when the switch FBS is kept closed, the mode is for displaying the reflected light amount due to the flash light emitting device or the brightness, with 1000 set in the registerBDR, and the operation of the .mu.-com 100 is shifted to a step #5 for effecting a new indication.
In the step #107, the operation of the .mu.-com 100 is shifted to a step #109 when the switch FBS is not closed. Steps #109 to #132 relate to the flow for setting data corresponding to the light measuring portions in the registers NDR1 and NDR2. In the above case, judgement is first made as to whether or not the data for the portion corresponding to the closed switch are in agreement with the content of the register NDR1, and if such data are in agreement therewith, the operation of the .mu.-com100 is shifted to the step #5, with the contents of the registers NDR1 and NDR2 left as they are, while on the contrary, if these data are not in agreement therewith, the content of the register NDR1 is transferred into the register NDR2, and the datafor the portion corresponding to the closed switch are set in the register NDR1 and the operation of the .mu.-com 100 is shifted to the step #5, and thus, fresh data are displayed at the steps subsequent to the step #5. In the step #129, if the switchAS is not kept closed, the operation of the .mu.-com 100 is shifted to the step #28, and the display time counting register is reset, and the .mu.-com 100 becomes the CEND state.
Referring to FIG. 13 showing a flow-chart for the 1 sec. function, if it is judged that the signal is of the 1 sec. signal at the step #1 of FIG. 10(A), the operation of the .mu.-com 100 is shifted to a step #140. In the step #140, it is judgedwhether or not the display time counting register COR is overflowing, i.e. whether or not a predetermined period of time is lapsed after resetting of the register COR. If the register COR is not overflowing, "1" is added to the content of the registerCOR and the .mu.-com 100 becomes the CEND state, while, if it is overflowing, "0" is set in the data taken-in completion judging flag IFJ and the display data calculation completion judging flag DFJ so that no display is effected even if any key function(except for that of the light measuring switch) is performed thereafter, with the blank data set in the display register so as to be output, and the .mu.-com 100 becomes the CEND state. Therefore, when the predetermined period of time is lapsed afterthe register COR has been reset (i.e. the light measuring switch MS is opened or other key operations are effected), the display is erased and subsequently, remains erased, unless the light measuring switch MS is closed for effecting the light measuringcalculation again.
Referring further to FIG. 14 showing a flow-chart for the power on/clear functions upon starting of power supply to the .mu.-com 100 due to replacement of the power source battery E, etc., when the power feeding to the .mu.-com 100 is initiated,the .mu.-com 100 starts functioning following the instruction from the specific address of the ROM 110 based on the function of said power on/clear circuit 101. In a step #150, specific exposure time Tvsc (for example, 1/60 sec.) is set in the registerTVR, the film sensitivity Svc (for example, ASA 100) is set in the register SVR, and the value .DELTA.fc (for example, 0) is set in the register DFR. Subsequently, the data 6 corresponding to the average are set in the register NDR1, while the data 1corresponding to the central light measuring portion P1 are set in the register NDR2. At a step #152, the data 0001 corresponding to the contrast display mode are set in the display mode selecting register BDR, and the data 0110 for taking-in Qv1 areset in the take-in data selecting register DIR. Thereafter, for arranging that the display is not effected when the key operations other than that of the light measuring switch MS is made, "0" is set in the take-in completion judging flag IFJ anddisplay data calculation completion judging flag DFJ, with blank data being set in the display data setting register so as to be output and the .mu.-com 100 becomes the CEND state.
It is to be noted here that, although in the foregoing embodiment, the weighted average is described to be obtained for the average value, the average value obtained need be limited to the weighted average, but may be of a harmonic average orgeometrical average. In the first place, the geometrical average is represented by ##EQU13## which will be converted into
which may be worked out by the normal calculating capacity of the .mu.-com 100. On the other hand, the harmonic average is represented by ##EQU14## and, since log.sub.2 5=2.3, further transformed into
Here, upon definition that
for obtaining x15, the relation as follows may be established
Firstly, on the assumption that
the relation will be
and thus, the following relation will be obtained
Subsequently, on the assumption that
the relation as follows will be established
Thereafter, the relations will be
and thus, x15 and also x are obtained.
In the above instance, although description is not given on the case where the data have exceeded the display limits, in such cases were the data goes over the display limits, it may be so arranged, for example, as disclosed in Japanese PatentApplication No. 54-154753, that data for critical values and blank data are alternately output upon judgement that the data have exceeded the display limits, so as to turn on and off the critical values for display.
Referring to FIG. 15 showing a modified display system according to the present invention, at display portions DP1 to DP5 corresponding in positions to the respective light measuring portions P1 to P5, the data obtained based on the lightmeasuring values of the respective light measuring portions are displayed, while the average value is indicated in a display portion DP6, with a display portion DP7 arranged to indicate the display modes. These display portions as described above may beconstituted by liquid crystal panels for indication in a view finder (not shown).
For displaying the contrast by the above display device, the display portion DP6 is kept blank, while in the display portions DP1 to DP5, the contrast between the average and each of the light measuring portions is displayed. By the abovearrangement, the contrast between the respective light measuring portions P1 to P5 may be directly read, since they are equivalent to the difference between the respective indicated values.
Reference is made to FIG. 16 showing a modification of the light measuring circuit described with reference to FIG. 9. In this modification, during the integrating function, the output of the transistor BT21 is converted into a voltage through aresistor R11 coupled thereto and to the emitter of the transistor BT11, and only the variation of the above voltage is taken out by a high pass filter constituted by a series connection of a capacitor C31 and a resistor R21, which is coupled to oppositeends of the resistor R11. More specifically, to a positive input terminal of an operational amplifier OA6 connected to the capacitor C31, a potential corresponding only to the variation of the output current of the photoelectric element PD1 due to thereflected light intensity by the flash light emitting device is impressed, and is converted into a current by a circuit constituted by the operational amplifier OA6 whose output is connected to a base of a transistor BT31, a resistor R31 connected to theemitter of the transistor BT31 which is further connected to a negative input terminal of the amplifier OA6, and a transistor BT41 whose base and collector are connected to the collector of the transistor BT31, and the converted current thus obtained iscaused to flow into the circuit constituted by the diodes D11 and D21 described earlier with reference to FIG. 9. Accordingly, the integrated voltage of the capacitor C11 may be regarded as corresponding to Qvfm1, and thus, it becomes unnecessary towork out Qvfm1 from the values Qv1 and Bv1.
It should be noted that the concept of the light measuring device according to the present invention may be applied to an exposure control device of a photographic camera. In the above case, it may be so arranged, for example, that, beforestarting of the exposure control, the flash light emitting device is preliminarily caused to emit flash light. And the light measuring device obtains the light amount to work out the contrast and exposure control values for the indication of thecontrast, and that the actual exposure control is effected after a photographer has checked such indication. In the above case, the exposure may be adapted to be controlled by the calculated exposure control value.
As is clear from the foregoing description, according to the light measuring device of the present invention, if the set value is successively altered while watching the contrast measured and displayed so as to take the photograph at the setvalue when the contrast reaches the desired value, it becomes possible to obtain photographs with desired contrast values through quantitative control of the contrast, which has been considered impossible up to the present.
SECOND EMBODIMENT
In a second embodiment of the present invention which is to be described hereinbelow with reference to FIGS. 17 to 29, the basic concept is to control the contrast in the scene to be photographed through employment of the auxiliary light source,for example, the flash light emitting device such as an electronic flash and the like.
More specifically, when the brightness at two portions are denoted by 2.sup.Bv1 and 2.sup.Bv2, and the reflected light amounts from the two portions by the auxiliary light are represented by 2.sup.Qvf1 and 2.sup.Qvf2 respectively, it may be soarranged that the value Tvx satisfying the equation
is obtained so as to control the exposure time to 2.sup.-Tvx, with the auxiliary light source being fired at the light emitting amount during the light measuring, whereby the contrast at the two portions reproduced on a photosensitive member iscontrolled to .DELTA.cs.
Reference is made to an electrical block diagram of FIG. 17 showing the construction of the light measuring device according to the second embodiment of the present invention in which the hatched signal lines represent those which deal withsignals of a plurality of bits.
In FIG. 17, the light measuring circuits 1 and 2 respectively for measuring different portions in the scene to be photographed have specific constructions as already described in detail with reference to FIG. 9 for the first embodiment. Thechange-over switches S1 and S2 are adapted to switch over the outputs of the light measuring circuits 1 and 2 between the integration circuits 3 and 5 and sample-hold circuits 4 and 6, and arranged to be connected to the terminals F1 and F2 by the lightmeasuring starting signal (not shown) and kept connected to said terminals F1 and F2 for the predetermined period of time 2.sup.-Tvc which is longer than the time period required for the full light emission by an ordinary flash light emitting device,while the switches S1 and S2 are kept connected to the terminals A1 and A2 during the periods other than the above. The switch S3 is closed by the light measuring starting signal (not shown) so as to fire the flash light emitting device FL. The outputof the integration circuit 3 has the value Qv1 which satisfies the equation
wherein Bv1 is the scene brightness due to the ambient light, 2.sup.-Tvc is the integrating time, and 2.sup.Qvfm1 is the reflected light amount by the flash light emitting device during the light measuring as also described earlier.
Similarly, the output of the integration circuit 5 is of the value Qv2 which satisfies the equation
The sample-and-hold circuits 4 and 6 are arranged to simultaneously sample and hold the outputs Bv1 and Bv2 of the light measuring circuits 1 and 2 at every predetermined period of time after the switches S1 and S2 have been connected to theterminals A1 and A2. The sample-and-hold is effected, in its timing, immediately after completion of the integrating function and maintained thereafter to such an extent that the display does not flicker after elapse of a predetermined period of timesubsequent to the termination of the calculation and display functions.
Upon completion of the first sample-and-hold, the analog multiplexer 7 first applies the signal for Qv1 to the A-D converter 8, and subsequently, develops the signal for Qv2, and then, produces signals in the order of Bv1 and Bv2. Meanwhile,upon completion of the sample-and-hold subsequent to the second time, the multiplexer 7 outputs only the signals for Bv1 and Bv2. The A-D converter 8 connected to the analog multiplexer 7 is arranged to subject the analog signal from the analogmultiplexer 7 to the A-D conversion. The digital de-multiplexer 9 coupled to the A-D converter 8 is further connected to the register 10 where the data of Qv1 are set, the register 11 where the data for Qv2 are set, the register 12 where the data forBv1 are set and the register 13 where the data for Bv2 are set. Upon termination of the first sample-and-hold, the above digital de-multiplexer 9 respectively applies the first A-D conversion value Qv1 to the register 10, the second A-D conversion valueQv2, to the register 11, the third A-D conversion value Bv1, to the register 12, and the fourth A-D conversion value Bv2, to the register 13, and upon termination of the sample-and-hold subsequent to the second time, also applies the first A-D conversionvalue Bv1 to the register 12, and the second A-D conversion value Bv2, to the register 13. Accordingly, the contents Qv1 and Qv2 of the registers 10 and 11 are not altered once set, unless integration is again effected by the operation of the lightmeasuring button, etc. (not shown). The data output circuit 14 from which the APEX value Tvc of the integration time is output is connected to a calculation section A to be mentioned below.
It is to be noted that the circuit portion of the light measuring device of FIG. 17 so far described is generally similar to that in the circuit arrangement in FIG. 1, with like parts being designated by like reference numerals.
The calculation section A coupled to the registers 10 to 13 and data output circuit 14 is intended to calculate the light amounts Qvfm1 and Qvfm2 reflected from the object to be photographed to the respective light measuring portions of the lightmeasuring circuits 1 and 2, owing to the light emission by the flash light emitting device FL based on the data from the registers 10 to 13 and the circuit 14, and is arranged to function upon completion of the data take-in to the registers 10, 11, 12and 13, and upon termination of the calculations of the data Qvfm1 and Qvfm2, not to function unless the data in the registers 10 and 11 are altered, i.e. unless the integration function is effected by the operation of the light measuring button, etc.(not shown).
Referring to the block diagram of FIG. 18 specifically showing the contents of calculation in the calculation section A, the calculation contents thereof will be described hereinbelow.
The subtraction circuits A7 and A8, the data Bv1 and Bv2 from the registers 12 and 13, and the data Tvc from the data output circuit 14 are applied so as to work out Bv1-Tvc and Bv2-Tvc, the data of which are respectively input to subtractioncircuits A3 and A4 coupled to said circuits A7 and A8, and based on the data therefrom and the data Qv1 to Qv2 from the registers 10 and 11, following equations are worked out.
The data .DELTA.11 and .DELTA.12 thus obtained are applied to data converting ROM A5 and A6 connected to the subtraction circuits A3 and A4 so as to be converted into data for log.sub.2 (s.sup..DELTA.11 -1) and log.sub.2 (2.sup..DELTA.12 -1), andthese data and the data from subtraction circuits A7 and A8 are applied to addition circuits A7.alpha. and A8.alpha. connected to the ROM A5 and A6 to work out the following equations.
and the data thus worked out are set in registers 70-1 and 70-2 coupled to the addition circuits A7.alpha. and A8.alpha.. The contents of these registers are not altered unless the integration function is effected again, since the calculationthereof is not performed so far as the integration is not effected again.
The process how the data Qvfm1 and Qvfm2 are worked out by the above equations 6-1 and 6-2 is described hereinbelow.
Upon elimination of Qv1 and Qv2 from the equations 4'-1 and 4'-2, and 5-1 and 5-2, the relations will be
and by taking the logarithm of both sides of each of the equations to the base of two, the equations 6-1 and 6-2 are obtained.
In FIG. 17, circuit 23 for producing the data .DELTA.f by which the light emission amount of the flash light emitting device FL during the photographing should be | | | |
