| 摘要 |
<p>PURPOSE:To enable uniform control of adjusting circuits by one voltage value and thereby to facilitate adjustment by providing the adjusting circuits in a plurality adjusting the sensitivity of amplifier units respectively. CONSTITUTION:When it is assumed that an output is delivered only from a detecting element 1a due to noise in a state wherein an object of detection, such as a human body, is not present in a detection area, only an output A out of ones of amplifier units 2a and 2b is generated, and no signal appears in an output B. Therefore, nothing comes out as an output of a comparator circuit 3. Accordingly, the object of detection is judged to be absent by a judgement circuit 4. When it is assumed that the object of detection is present in the detection area, infrared rays are detected by both detecting elements 1a and 1b, and the outputs A and B of the amplifier units 2a and 2b come out as the same signal. Accordingly, signal is outputted from the comparator circuit 3 and a detection output is delivered by the judgement circuit 4. A voltage division ratio between adjusting circuits 5a and 5b for adjustment of the sensitivity of the amplifiers 2a and 2b can be only by adjustment of a variable resistance 6, in this constitution, and therefore the adjustment of the sensitivity of the amplifier units is simplified.</p> |
