Resources Contact Us Home
Noncontact temperature measuring device

Image Number 6 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
Method of reducing acetaldehyde in polyesters, and polyesters therefrom
Polypeptides and immunizing compositions containing gram positive polypeptides and methods of use
Optical scanner and image-forming device
Liquid crystal display device
System and methods for facilitating and documenting user thinking and learning using enhanced interactive constructs
Method and system for coding an information signal using closed loop adaptive bit allocation
Lubricant supplying device, process cartridge, and image forming apparatus
  Randomly Featured Patents
Method of attaching a fastening element to a panel
Active power line conditioner with fundamental negative sequence compensation
LED driver circuit having a bias current drawn from a load current
Composition for measuring glucose having improved substrate specificity
Display case
Stable bioactive somatotropins
Systems and method for monitoring consumable supply levels in one or more printers
Substituted thieno[3,4-B]thiophene polymers, method of making, and use thereof
Circuit arrangement comprising having plurality of half bridges
Wall box