Photoelectric smoke detector and process for testing the photoelectric smoke detector

摘要

A photoelectric smoke detector 1 for detecting smoke particles 4 is disclosed, the smoke detector 1 comprising: a light emitting element 5, a light receiving element 6 for receiving light 8 emitted by the light emitting element 5 and scattered by the smoke particles 4 and for outputting a detection signal 12 obtained by photoelectrical converting the received light 10, 11, an amplifier circuit 13 for amplifying the detection signal 12 and providing an amplified output signal 14, wherein the amplified output signal 14 may be divided into an offset-signal 20 and an amplified detection signal 21, whereby the photoelectric smoke detector 1 is adapted to operate in a pulsed mode, so that the detection signal 12 comprises high-frequency components, whereby the amplified detection signal 21 is determined by high-frequency components of the detection signal 12 and that the offset-signal 20 is determined by low-frequency components of the detection signal 12 and/or by low-frequency components of at least an intermediate signal based on the detection signal 12, and whereby the amplifier circuit 13 is adapted to transfer the high-frequency components with a higher gain and to transfer the low-frequency components with a lower gain in order to improve the signal ratio between the amplified detection signal 21 and the offset-signal 20.

主权项

1. A photoelectric smoke detector (1) for detecting smoke particles (4), the smoke detector (1) comprising:
a light emitting element (5), a light receiving element (6) for receiving light (8) emitted by the light emitting element (5) and scattered by the smoke particles (4) and for outputting a detection signal (12) obtained by photo-electrically converting the received light (10, 11), an amplifier circuit (13) for amplifying the detection signal (12) and providing an amplified output signal (14), wherein the amplified output signal (14) may be divided into an offset-signal (20) and an amplified detection signal (21), whereby the photoelectric smoke detector (1) is adapted to operate in a pulsed mode, so that the detection signal (12) comprises high-frequency components, characterized in that the amplified detection signal (21) is determined by high-frequency components of the detection signal (12) and that the offset-signal (20) is determined based on the detection signal (12), whereby the amplifier circuit (13) is adapted to transfer the high-frequency components with a higher gain and to transfer the low-frequency components with a lower gain in order to improve the signal ratio between the amplified detection signal (21) and the offset-signal (20).