CONTROL CIRCUIT FOR PREVENTING SATURATION OF SIGNAL TRANSMISSION AND RECEPTION SYSTEM

摘要

PURPOSE: A control circuit for preventing saturation of a signal transmission and a reception system is provided to prevent a malfunction by restricting saturation of an infrared sensor portion due to an external light. CONSTITUTION: A pulse signal generation portion(16) is used for generating a voltage of or a current pulse of a desired waveform. A light emitting diode drive portion(18) is used for driving a light emitting diode(2). The fourth resistance(20) is used for diving Vcc into predetermined voltages. A photo diode(21) is connected reversely between the sixth resistance(24) and the ground stage. The first capacitor(26) is connected between the fifth resistance(22) and the sixth resistance(24) connected between Vcc and a ground stage. The second capacitor(28) is connected between the sixth resistance(24) and the photo diode(21). The eighth and the ninth resistances(36,38) are connected with the ground stage in order to divide Vcc. A comparator(30) has a non-inverse terminal(+) connected with the eighth and the ninth resistances(36,38). The third capacitor(34) is connected parallel among the eighth and the ninth resistances(36,38) and the non-inverse terminal(+) of the comparator(30).