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Class Information
Number: 396/126
Name: Photography > With exposure objective focusing means, focusing aid, or rangefinding means > Processing circuit > Null type or zero-difference type
Description: Subject matter wherein the processing circuit generates two signals and detects an in focus condition when the two signals are essentially equal in magnitude.
Patents under this class:
| Patent Number |
Title Of Patent |
Date Issued |
| 7262984 |
Method and apparatus for storing and reading information in a ferroelectric material |
Aug. 28, 2007 |
| 5612763 |
Focus detection device and method |
Mar. 18, 1997 |
| 5565954 |
Range finder for passive-type autofocusing device |
Oct. 15, 1996 |
| 5488449 |
Infinite-distance detecting circuit for an auto-focus system |
Jan. 30, 1996 |
| 5298934 |
Range finder for passive type autofocussing device |
Mar. 29, 1994 |
| 5264891 |
Range finder for passive-type autofocusing device |
Nov. 23, 1993 |
| 4616264 |
Auto focus system |
Oct. 7, 1986 |
| 4614975 |
Focus area change circuit |
Sep. 30, 1986 |
| 4568168 |
Focus detecting system |
Feb. 4, 1986 |
| 4550994 |
Focusing control device |
Nov. 5, 1985 |
| 4315674 |
Focal point detecting system |
Feb. 16, 1982 |
| 4253752 |
Focus condition detecting device |
Mar. 3, 1981 |
| 4060325 |
Automatic focusing system employing two variable frequency oscillators |
Nov. 29, 1977 |
| 4010479 |
Focusing apparatus for optical systems |
Mar. 1, 1977 |
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