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
Non-serialized electronic product registration system and method of operating same
Portable communication terminal, communication method and control program
Devices including composite thermal capacitors
Caching techniques
Method of and apparatus for image denoising
Method and apparatus for optimizing paging in a communication network
Reducing voltage stress in a flyback converter design
  Randomly Featured Patents
Machining of ceramic materials
Signature gathering machine
Image reading apparatus
Picture frame
Plane-parallel structures of silicon/silicon oxide
Rubber vulcanization agents of sulfur olefin adduct
Recording soil penetrometer
Apparatus for forming curls in reinforcing material-attached profile strip, method for producing spiral pipe, and apparatus for producing spiral pipe
Low self-bias variable gap diode
Lighting arrangement for photographic work including combined spot and flood light luminaire