| 摘要 |
PROBLEM TO BE SOLVED: To provide a failure detection circuit capable of reducing the manufacturing cost, and an alarm having this. SOLUTION: The failure detection circuit of an LED comprises a plurality of LEDs 1a-1c, a plurality of switching elements 3a-3c that are connected with the plurality of LEDs 1a-1c and controlled so that current flows from a power supply Vcc to the LEDs, respectively, and a microcomputer 2 for outputting a control signal for ON-controlling the plurality of switching elements 3a-3c and detecting a failure of the LEDs when current flowing in the LEDs 1a-1c is not within a normal value range. One detection resistor 4 is connected between the power supply Vcc and the plurality of switching elements 3a-3c, one input port P4 into which a detection output by the detection resistor 4 is input is disposed in the microcomputer 2, and the microcomputer 2 detects a failure of the LEDs based on the detection output input into the input port P4. COPYRIGHT: (C)2007,JPO&INPIT
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