| 摘要 |
An optical smoke detector which includes a light source and light sensing element so arranged that the quantity of light detected by the element will be determined by the presence of smoke in the detector, a power source for periodically supplying sets of actuating pulses to the light source, apparatus connected with the light sensing element for detecting light pulses which are synchronized with the actuating pulses and producing an alarm when pulses of a predetermined magnitude are detected.
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