To provide an infrared sensor device capable of improving the S/N ratio.
The infrared sensor device is provided with an infrared sensor IS for generating analog output values corresponding to temperature changes due to the absorption of infrared rays; a modulator 3 for modulating the output of the infrared sensor IS by modulating pulses (modulating signals), having a frequency sufficiently high with respect to the frequency of a signal component; an amplifier 4 for amplifying output of the modulator 3; and a demodulator 6 for extracting output of the amplifier 4, by demodulating pulses (modulating signals) synchronized with the modulating pulses. An analog low-pass filter 7, provided for the subsequent stage of the demodulator 6, removes flicker noise produced in the amplifier 4. The infrared sensor device is provided with both an A/D converter 8 for converting the output of the analog low-pass filter 7 from analog into digital form at a sufficiently fast sampling frequency, with respect to the frequency of the signal component of the infrared sensor IS and a digital low-pass filter 9, provided for the side of the subsequent stage of the A/D converter 8 and removes a part of the white noise by the digital low-pass filter 9.
COPYRIGHT: (C)2008,JPO&INPIT
Yoshifumi Watanabe
Satoshi Hyodo
Yuji Takada
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