PURPOSE: To protect a transistor chopper for driving a reduction gear drive motor against breakdown due to short circuit current for power transistor.
CONSTITUTION: Upon receiving a drive signal for rotating a motor 6 forward from a control circuit, a transistor chopper turns transistors TR1, TR4 ON whereas the transistor chopper turns transistors TR2, TR3 ON when the motor 6 is rotated reversely. If the transistor TR2 is turned ON under forward control of the motor 6, short circuit current flows into the transistors TR2, TR4 to cause breakdown thereof. In order to protect the transistors against breakdown, a transistor TR5 is provided as an interlock circuit for blocking concurrent turn ON of the transistors TR2, TR4. The transistor TR1 is interlocked under reverse rotation control.
TSUJI TOSHITAKA
KITO MASAZUMI
YAMADA SADAO
