| 摘要 |
PURPOSE:To prevent the erroneous operation of a circuit due to the effect of the temp. characteristic inherent to an optical sensor or disturbance, by converting the analogue output detected by the optical sensor to digital output subjected to time sharing and calculating the differential value of said data and detecting a part to be detected on the basis of the detected wave form of said differential value. CONSTITUTION:When an optical sensor 24 detects a part to be detected different in light transmissivity, the light receiving quantity of a light receiving element 23 changes and the voltage on the side of a collector 25 varies and output voltage Vout of the analogue wave form on the side of the collector 25 appears. The output voltage Vout of this analogue wave form is timewise divided at an equal interval >=t by an A/D converter 18 to be converted to digital wave form (S1...S15). Then, the digital value S1 is subtracted from the digital value S2 using RAM 19 and ROM 20 to calculate difference d1. Next, when the difference d1 is divided by the interval DELTAt subjected to time sharing, a differential value D1 is calculated. Hereinafter, in the same way, differential values (D2,...D14) are calculated. By calculating the differential values (D1..., D14) by this method, the change quantity and change direction (+/-) of the output voltage Vout can be investigated.
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