We have developed a two-dimensional thermal infrared array sensor called the Infrared Position Sensitive Detector
(IRPSD). The IRPSD has two thermometers for row and column in a pixel, and thermometers in a row or column are
serially connected. The serial connection of thermometers produces the sum of signals from the pixels in each row and
column. With this array architecture, the IRPSD can extract some specific information without digital image processing.
The IRPSD is capable of performing position detection and number counting operations for hot (or cold) objects.
Information on the position can be obtained from the row and column that has maximum outputs, and the number can be
counted by adding all outputs in rows or columns. We adapt a thermopile made of a p-type polysilicon and aluminum as
thermometers. We have developed two IRPSDs. One is a prototype device for verifying the concept, and the other is an
improved device with higher responsivity. Evaluation of these devices has shown that the IRPSD has the potential to be
applied to a wide variety of applications.