| 摘要 |
An optical scatter smoke sensor comprises a base 10 and a removable head 11. An optical emitter 18 and detector 19 are disposed on the base 10 and project into a smoke chamber 15 in the head 11, when the head 11 is mounted to the base 10. The optical emitter 18 and detector 19 are normally obscured from each other and the alarm is triggered when the output of the detector 19 exceeds a threshold value, due to scatter in the chamber 15. When the head 11 is removed from the base 10, the optical emitter 18 and detector 19 are no longer obsured from each other and the output of the detector 19 is measured again, so that the sensitivity of the sensor can be adjusted in order to compensate for contamination and/or component ageing. |
