| 摘要 |
PURPOSE:To improve the accuracy at a long distance and to reduce circuit scale by providing a multiple-division photodetector and analog switches corresponding to it. CONSTITUTION:The analog sensors 21a - 21d are arranged corresponding to sensors, whose cathodes are connected to a reference voltage 26. The respective switches are initially off and when signal light is entered into a sensor, a photoelectromotive current is generated, shunt by resistances 22a - 22e, and passed through an operational amplifier 24 to generate a signal voltage at an output terminal 25. When the signal voltage generated at the terminal 25 is less than a constant value, the infinite distance is decided. Then when the signal voltage generated at the terminal 25 is larger than the constant value, the switches 21a - 21d are turned on in order. Thus, when the photosensor where the signal light is incident is connected to the voltage 256, the signal voltage at the terminal 25 becomes zero and the position of a signal spot is detected. |
