DETERIORATION DETECTOR FOR LIGHT EMITTING ELEMENT OF OPTICAL THYRISTOR

摘要

PURPOSE: To detect the deterioration and failure of a light emitting element in an early stage so as to support the maintenance information required for taking the optimum measure against the fault by outputting optical pulse signals outputted from a light emitting element for monitoring as electric signals proportional to the peak value of the signals and detecting the deterioration of the light emitting element based on the output. CONSTITUTION: When a switching element 4 is turned on/off with pulse signals from a gate control circuit 3, the same pulse current flows to normal light emitting elements L1 -Ln and a light emitting element Lm for monitoring and the elements L1 -Ln and Lm are operated under the same condition. When the operating state continues for a prescribed period of time of the cumulative value of the operating time exceeds a certain value, all of the light emitting elements start to deteriorate. When the light emitting elements start to deteriorate, the peak value of the optical pulse signals fed to a circuit 2 which detects the deterioration of the elements L1 -Ln from the element Lm for monitoring through a light guide 1A drops and the level of the output signals of the circuit 2 also drops. Therefore, the deteriorating states of the elements L1 -Ln can be recognized equivalently.