| 摘要 |
PROBLEM TO BE SOLVED: To find a fire being set accurately in its early stage and to prevent the fire from spreading by deciding that a fire is set when flames last for longer than a certain time and making a buzzer sound. SOLUTION: When flames F are generated, a flame detector 1B detects specific wavelength of infrared rays R and ultraviolet rays V radiated by the flames F and outputs a flame detection signal S1 to a control circuit 1A. The control circuit 1A having received the flame detection signal S1 detects the continuance of the flames F through a timer 1C, but does not output a fire-raising signal S2 by deciding that a cigarette, etc., is lit and a fire is not set when the continuance is shorter than a certain time. If, however, the detected continuance exceeds the certain time, the control circuit 1A judges that a fire is set and sends the fire-raising signal S2 to a warning circuit 1D. Consequently, the warning circuit 1D sends a driving signal S3 to the buzzer 1G, which generates an alarm AL.
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