| 摘要 |
PURPOSE:To avoid an error of the digital signal which is caused by the change of temperature, by converting the original read voltage into the quantity having no relation with the temperature and then comparing the converted read voltage based on the middle level between the voltage with irradiation of light and the voltage with no irradiation of light. CONSTITUTION:The transistors T1-Tn are turned on successively by the driving pulse, and the voltage at the connection points between the photoelectric effect elements S1-Sn and the load resistance RL are transmitted successively in the form of the signal (a). The photoelectric transducer SO of the temperature compensating sensor 12 is always masked to secure a constant temperature, and thus the voltage of the signal (b) becomes constant. Then the differential voltage between the signals (a) and (b) is amplified by the differential amplifier 13 to transmit the signal (c). The signal (c) is monitored by the peak holding circuit 14, and the maximum value (e) of the signal is stored. The comparator 15 identifies the signal (c) based on the signal (e) having the voltage of 1/2 maximum voltage to transmit the digital signal (f). Thus the reference voltage having no relation with the temperature is set for comparison. As a result, the error which is caused by the change of temperature is reduced for the digital signal. |
