| 摘要 |
<p>PURPOSE:To detect the presence in the optimum state at all times by arranging a light emitting diode and a photodetector transistor (TR) at an interval in detecting the presence of an object to be detected optically, inserting the object to be detected between them so as to detect a logical value produced in the TR. CONSTITUTION:A light emitting diode 6 is provided between a constant voltage source VDD and ground via a resistor 4 and a current is flowing thereto is controlled by using a current control section 1, a D/A converter 2 and a differential amplifier 3. Moreover a photo TR 7 opposed to the diode 6 at an interval is connected between a constant voltage source Vcc and ground via a resistor 8 and the object to be detected PR is inserted between the diode 6 and the TR 7. Through the constitution above, a signal outputted from the TR 7 is given to an output buffer 9 having a hysteresis characteristic by the presence of the object PR, the logical value signal So of 'H', 'L' is sent to a discrimination section 10, where the presence of the object PR is recognized surely.</p> |
