| 摘要 |
The invention is directed to an alarm shut-off device for an alarm clock or timer permitting a signal delivered by the clock to be interupted or to be cancelled in that the user of the clock approaches the clock or merely moves a part of his body, for example, his hand, towards the clock. Preferably, the clock is equipped with a transmitter 2, 2' emitting infrared radiation or ultrasonic waves and a corresponding receiver 3, 3' which detects the infrared radiation or the ultasonic waves reflected by the moved body part 1. A signal shaping network 4, 5 and 6 determines the variation of the intensity with time, which variation is compared in a threshold switching stage 7 with a predeterminable value which, when exceeded, causes the alarm signal A to be shut off.
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