PURPOSE: To obtain a zero phase signal of power supply voltage having an optional width and risen from a zero phase point of the power supply by providing a constant voltage diode, the 1st and the 2nd resistors, a capacitor 14, a buffer circuit and a dissidence circuit.
CONSTITUTION: A power supply voltage is divided by the constant voltage diode 11 and the 1st resistor 12, an inverse voltage limited by a Zener voltage is applied to the constant voltage diode 11 at each half wave and a rectangular wave in synchronizing with the power supply voltage is generated. The 2nd resistor 13 and the capacitor 14 divide an applied voltage Vz of the constant voltage diode 11 to constitute a charge/discharge circuit. The voltage VE of the capacitor 14 is applied to the buffer circuit 15 as an input and a rectangular wave output VF having a little delay than the Vz compared with a threshold value is generated. The dissidence circuit 16 ORs exclusively the applied voltage Vz with the output voltage VF of the buffer circuit 15, and the rectangular wave risen from the zero phase point of the power supply voltage is outputted. Further, the width of the output waveform in this case can be changed freely depending on the time constant comprising the resistor 13 and the capacitor 14.
KIUCHI MITSUSACHI
IMAHASHI HISASHI
