| 摘要 |
A smoke detector comprises a light emitter (10) and a light receiver (11). Normally, light from the light emitter (10) is partially absorbed and partially deflected by parallel posts (2, 3) which lie on a straight line (21) on which the light emitter (10) and the light receiver (11) also lie, with the result that no signal is generated. When smoke enters a chamber (6) containing the posts (2, 3) it causes the light to be diffused and sufficient light reaches the light receiver to cause the generation of an electrical signal. The light emitter, posts, and light receiver may be mounted on a plate (1, Figure 2) which has a circular ring of baffle posts (4, Figure 2) which prevent outside light entering the smoke detector. <IMAGE> |
