PURPOSE: To prevent a breakdown due to the backward voltage at a collector terminal, by connecting a diode in its forward direction to the collector of a transistor (TR) which drives a capacitive load.

CONSTITUTION: When a pulse generation command is applied to an input terminal P1, a TR3 turns on and a TR4 turns off, generating a positive pulse at a point Q1. At this time, the positive pulse is applied to a point Q2 as well, but a diode D2 turns off, so a TR6 is not broken down. When the pulse generation command is supplied to an input terminal P2, a TR5 turns on and the TR6 turns off to generate a negative pulse at the point Q2. At this time, a diode D1 turns off to prevent the TR4 from being broken down. A capacitive load is connected to a point A.