Low-cost thermo-electric infrared FPAsand their automotive applications

摘要

This paper describes three low-cost infrared focal plane arrays (FPAs) having a 1,536, 2,304, and 10,800 elements andexperimental vehicle systems. They have a low-cost potential because each element consists of p-n polysiliconthermocouples, which allows the use of low-cost ultra-fine micro-fabrication technology commonly employed in theconventional semiconductor manufacturing processes. To increase the responsivity of FPA, we have developed aprecisely patterned Au-black absorber that has high infrared absorptivity of more than 90%. The FPA having a 2,304elements achieved high resposivity of 4,300 V/W. In order to reduce package cost, we developed a vacuum-sealedpackage integrated with a molded ZnS lens. The camera aiming the temperature measurement of a passenger cabin iscompact and light weight devices that measures 45 x 45 x 30 mm and weighs 190 g. The camera achieves a noiseequivalent temperature deviation (NETD) of less than 0.7°C from 0 to 40°C. In this paper, we also present a severalexperimental systems that use infrared cameras. One experimental system is a blind spot pedestrian warning system thatemploys four infrared cameras. It can detect the infrared radiation emitted from a human body and alerts the driver whena pedestrian is in a blind spot. The system can also prevent the vehicle from moving in the direction of the pedestrian.Another system uses a visible-light camera and infrared sensors to detect the presence of a pedestrian in a rear blind spotand alerts the driver. The third system is a new type of human-machine interface system that enables the driver to controlthe car's audio system without letting go of the steering wheel. Uncooled infrared cameras are still costly, which limitstheir automotive use to high-end luxury cars at present. To promote widespread use of IR imaging sensors on vehicles,we need to reduce their cost further.