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
Switchable memory diodes based on ferroelectric/conjugated polymer heterostructures and/or their composites
Method of making an array of nucleic acid colonies
Extract of Vanilla planifolia
Approaching object detection system
Vacuum cleaner
Watch dial
Process for shaping polymeric articles
  Randomly Featured Patents
Dual-modality imaging
Pelargonium graveolens plant named `Narmada`
Liquid crystal display device
Photodetector involving a MOSFET having a floating gate
Device for storing and applying cosmetics
Method and apparatus for the detection of accumulations of particles such as metaphase plates
Multiple pack of individually packaged items, method and apparatus for producing same
Vehicle brake system
NO polymerization inhibitor for vinyl aromatic compound distillation
Tonnage regulating structure and a mold incorporating same