Patent ID: 7301640
Filing Date: 2007-11-27
Classification: G01N

Abstract:
1. A gas detector for sensing a predetermined gas comprising: a processor and associated circuitry; a sensing chamber into which at least a selected gas from an external environment can flow; a light emitter; a reflector that reflects light from the light emitter and has a heater which is at least one of attached to, or, part of the reflector wherein the heater is electrically connected to the processor and associated circuitry; a first sensor that senses reflected light from the reflector and provides a first signal indicative of a predetermined gas in the sensing chamber; a second sensor, the second sensor senses light reflected from the reflector and provides a second signal not indicative of a predetermined gas, the second signal is responsive, at least in part, to condensation on the reflector, the processor and associated circuitry receive the first signal and second signal; a sensor of the external environment which provides a third signal indicative thereof; the processor includes software that processes the first signal, the second signal, and the third signal and responsive thereto, the processor causes power to be dissipated in the heater intermittently, in response to at least the second signal, to minimize condensation on the reflector, and, the processor, in response to at least the first and second signals, determines the presence of the predetermined gas.