PURPOSE: To control a load by the switching of a latch type switch by using a parallel circuit of anti-parallel connection between a light emitting element driven by the 1st positive pulse and a light emitting element driven by the later negative pulse so as to control a thyristor and a transistor connected in parallel with a load.
CONSTITUTION: With a positive pulse 8a given, a light emitting element 1 is driven and lighted. The thyristor 3 is conductive and the load 7 is energized. Even at a loss of a gate signal, the load 7 keeps the on-state. In order to turn off the load 7, a negative pulse is applied to a light emitting element 2 coupled optically with a photodetection bias circuit 6 of a TR 4. With a negative pulse 8b given, the light emitting element 2 is lighted, the TR 4 is conductive and the thyristor 3 is out off, Since the TR 4 is also cut off because of the loss of the input pulse 8b, the load 7 is deenergized.
IITAKA YUKIO
YAMAGUCHI SHUICHIRO
