| 摘要 |
A light emitting device for emitting pulse lights synchronized with a pulse signal is provided. A light receiving device for receiving the pulse lights reflected by or penetrating an object to be detected is provided. A signal processing circuit for detecting whether the object exists or not, based on a light receiving signal from the light receiving device. A synchronization timing circuit for generating the pulse signal used for emitting a plurality of pulse lights in one cycle is provided. The signal processing circuit detects the plurality of pulses and outputs a detection signal for indicating whether the object exists or not.
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