Patent ID: 9243954
Filing Date: 2016-01-26
CPC Classification: G01J

Claim Text:
1. A circuit for controlling an IR emitter for an analyzer comprising: An IR emitter having an input and an output; An oscillator which provide a first frequency modulation signal which is a square wave having on and off duration which are equal, said square wave first frequency modulation signal applied to said input of said IR emitter for powering said IR emitter, said oscillator further providing a second frequency modulation signal applied to said input of said IR emitter during an on-time of said first frequency modulation signal, wherein the frequency of said second frequency modulation signal is higher than the frequency of said first modulation signal; A pyroelectric detector coupled to said output of said IR emitter; and A second circuit coupled to said pyroelectric detector, said second circuit including an amplifier for providing unipolar output signals which are applied to a low pass filter for passing signals having a frequency corresponding to said first frequency modulation signal.