| 摘要 |
PURPOSE:To facilitate wiring works and the like by a method wherein rays are introduced into a detector having directional couplers provided at prescribed apertures through the intermediary of the directional couplers and thereby the device can be constituted by a signal optical fiber. CONSTITUTION:The light from a light-emitting part 1 is transmitted to the 1st smoke sensor 5a and the 2nd smoke sensor 5b by the optical fiber 2 through the intermediary of the 1st directional coulper 4. In the smoke sensors 5a and 5b a pair of directional couplers 6a, 6a' and 6b, 6b' are provided respectively. In the sensor 5a, the light which gets in A branches at C1, radiates from B, gets in A3, branches at O2 and returns again to the original position. A part of the light from A reaches A4 through C2. And, when there is no smoke between B and A3, it returns again to the optical fiber 2, and the light which, reaches a photoreceiving part 3 turns a switch not shown in the figure on, lighting a lamp. When there is any smoke, the quantity of the light which is received is reduced and the switch is turned off, while the lamp is put off. |
