| 摘要 |
PROBLEM TO BE SOLVED: To provide a photoelectric smoke sensor capable of adjusting sensitivity thereof with ease and high precision. SOLUTION: The sensor drives to emit light from a light emitting LED 10a intermittently by a pulse signal and senses a fire by receiving scattered light of the smoke resulting form the light from the LED 10a with a light receiving element 11a. A light emitting pulse width control part 16 provided as a function of a CPU 6 controls the pulse width of the pulse signal to drive to emit the light from the LED 10a to adjust the sensor to obtain a prescribed sensitivity. In particular, the control part 16 makes a light receiving output value corresponding to the prescribed sensitivity be a target value, and automatically controls the pulse width of the light emitting pulse signal so as to match it with the target value to obtain an adjustment value. COPYRIGHT: (C)2004,JPO&NCIPI
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