| 摘要 |
PROBLEM TO BE SOLVED: To eliminate noise which occurs when an illumination device is lighted in an information display device. SOLUTION: When a toggle switch 120 is operated, second CPU 122 turns on an FET switch 108, supplies DC voltage to a lighting circuit 110 and lights a transparent illumination device 17. The muting circuit 112a of an amplification circuit 112 is operated, the output level of the amplification circuit 112 is dropped and a clocking operation in second CPU 122 is started. Second CPU 122 decides prescribed time tw based on the temperature of the transparent illumination device 17 that a temperature detection circuit 123b detects and terminates the operation of the muting circuit 112a of the amplification circuit 112.
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