| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared crime prevention device that can prevent erroneous detection of an intruder when excess light irradiates an infrared light receiving element as disturbance light in a reception part to saturate a conversion voltage, in a structure in which a transmission part transmits pulsed infrared rays of a predetermined carrier frequency, the reception part having the infrared light receiving element receives the infrared rays, a voltage conversion part converts a conversion current of the infrared rays received by the reception part into a conversion voltage, a frequency component extraction means extracts the carrier frequency component from the conversion voltage, and a determination part determines that there is an intruder if the magnitude of the carrier frequency component is not larger than a specified value. SOLUTION: An erroneous intruder detection prevention means 4 comprising a low pass filter 41 and a level determination circuit 42 is provided for detecting a saturation state to cancel or suspend a determination that there is an intruder when a conversion voltage 30 converted in the voltage conversion part 3 is saturated. COPYRIGHT: (C)2006,JPO&NCIPI |
