Resources Contact Us Home
Noncontact temperature measuring device

Image Number 2 for United States Patent #4456390.

A portable, battery operated noncontact temperature measuring device including a lens for collecting infrared radiation and a thermopile for producing a signal indicative of the intensity thereof. The thermopile signal is amplified, linearized and summed with an ambient temperature signal derived from a temperature responsive element, e.g. a diode chip mounted immediately adjacent a cold junction of the thermopile. The resulting composite temperature signal is then processed and displayed. The ambient temperature signal is also utilized to control the impedance of a dual field effect transistor, which in turn controls the gain of the amplifier. Thus, temperature induced variations in the responsivity of the thermopile are compensated by corresponding changes in the gain of the amplifier. An adjustable high impedance bias circuit provides bias current to the input of the amplifier, insuring that the signal at the output of the amplifier will not be affected by temperature induced changes in the internal resistance of the thermopile. A switching circuit alternately connects the output of the thermopile and a resistor having a resistance approximately equal to the internal resistance of the thermopile to the input of the amplifier. When the resistor is so connected, an automatic zeroing circuit reduces the amplifier output to approximately zero, thereby essentially eliminating amplifier drift.

  Recently Added Patents
Oxide material, electrophotographic photoreceptor, process cartridge, and image forming device
Playback device, playback method, and computer program
Electronic apparatus and manufacturing method of electronic apparatus
Method and apparatus for reacquiring lines in a cache
Reliability fire pressure switch
Summarization of short comments
System for alarming upon occurrence of secession of smart key for vehicles
  Randomly Featured Patents
Highly oriented fluoropolymer films
Driving apparatus and image forming device having the same
Fishing lure
Keyless deadbolt door lock assembly
Representing network link and connection information in a graphical user interface suitable for network management
High speed operational amplifier
Ski stick
Juice extractor
Graphical user interface for interactive construction of typical cross-section frameworks
Articulated vehicle