| 摘要 |
PROBLEM TO BE SOLVED: To provide a monitoring circuit of lamp life capable of reducing manufacturing costs. SOLUTION: The monitoring circuit includes a memory for recording accumulated time showing lighting time of a light-emitting device and operating time of an output control unit while specified time is recorded in advance on the basis of life of the light-emitting device or the output control unit, a timer starting time measurement from accumulated time read out from the memory on the basis of starting of power supply and periodically updating measuring time as accumulated time and updating the measuring time as accumulated time when there are instructions for recording of measuring time, a comparator for comparing the specified time and the accumulated time and transmitting a report signal to the output control unit in order to report that the measuring time reaches to the specified time when both time is coincided, a voltage detection unit for supplying power to a timer, the memory, and the comparator while the light-emitting device is lighted up and instructing recording of the measuring time to the timer when applied voltage becomes a threshold or below, and an auxiliary power supply element for supplying power to the timer when power supply is stopped from the voltage detection unit to the timer. COPYRIGHT: (C)2010,JPO&INPIT |
