| 摘要 |
<p>PURPOSE:To identify a sensor which is alarming even in the case a plurality of sensors are connected in a circuit series of a district indicator. CONSTITUTION:A luminous drive circuit 22 receives pulses 12 from a oscillator circuit 20 to cause luminescence in luminous elements 23, 24. The outputs of light reception elements 25, 26 are amplified in an amplifier 27 and are input through a switch circuit 28 to a level detection circuit 29 and the state of opening and shutting of a shutter is detected. An output circuit 30 does not function when the output from the level detection circuit 29 is in high level but it outputs alarm signal to the district indicator and turns on an alarm light 11 when the output from the level detection circuit is in low level. A memory light drive circuit 31 does not function when the output from the level detection circuit 29 is in high level. However, when the output from the level detection circuit 29 becomes low level, it turns on a memory light 12 from that moment for a period T1.</p> |
