Non-dispersive infrared gas detector, and method of stabilizing infrared emission of an incandescent lamp

A non-dispersive infrared (NDIR) gas detector comprising:

• an incandescent lamp having an incandescent filament and capable of emitting IR radiation with a continuous spectrum;
• an IR detector for selectively sensing the characteristic wavelength of a wave radiated from a specific gas to be detected;
• a gas chamber for allowing the specific gas to flow between said incandescent lamp and said IR detector therethrough;
• a photodetector located in proximity of said incandescent lamp to detect a portion of stray visible light emitted from said incandescent lamp so as to generate an induced electrical signal corresponding to the stray visible light detected by said photodetector;
• an electronic control unit connected electrically to said photodetector for receiving the induced electrical signal therefrom, and comparing the induced electrical signal with a preset reference signal so as to generate a feedback control signal indicative of a level difference between the induced electrical signal and the preset reference signal, the preset reference signal being associated with a predetermined constant level of the stray visible light corresponding to a constant temperature of said incandescent filament;
• and
• a power unit connected electrically to said electronic control unit and said incandescent lamp, said power unit being operative to repeatedly regulate electrical power supplied to said incandescent lamp based on the feedback control signal from said electronic control unit until the induced electrical signal and the preset reference signal have the same level;
• wherein, when the induced electrical signal and the preset reference signal have the same level, IR emission of said incandescent lamp is stable in response to said incandescent filament being kept at the constant temperature.