Alarm silencing circuit for photoelectric smoke detector.

摘要

P A photoelectric type detector which can be silenced includes a radiant energy source (12) and a detector (14). A generator circuit (36) produces a sequence of pulses to energize the source (12). A bias circuit (22) polarizes the detector (14). The detector can be temporarily silenced when it is in alarm by reducing the energy level of the pulses or by changing the polarization point of the detector (14) for a certain period of time. The time period can be established by means of an RC circuit. The effect of reducing the energy level or changing the polarization point is to reduce the sensitivity level of the detector (14) temporarily. /P