| 摘要 |
PURPOSE:To decrease a power consumption and improve a reliability by using a liquid crystal displaying body for a chopper combined with a pyroelectric infrared sensor. CONSTITUTION:A liquid crystal displaying body 2 drived on or off as a chopper is arranged just in front of the pyroelectric infrared sensor 1, and the light made incident to the sensor 1 is controlled by the body 2. An absolute output of the sensor 1 is sent to a microprocessor 5 through an interface circuit 4. The output of the sensor 1 is processed variously by said processor 5. If it is judged as fire, the alarm is generated from an alarm generating device 6. |
