Infrared crime prevention device



PROBLEM TO BE SOLVED: To provide an infrared crime prevention device that can suppress the saturation of a conversion voltage in a voltage conversion part that converts a conversion current of a reception part into a conversion voltage, even when excess light irradiates an infrared light receiving element as disturbance light in the reception part, 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, the 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: The voltage conversion part 3 is provided with an LC resonance circuit 4 for substantially maximizing the conversion efficiency of a carrier frequency component 30a of a conversion voltage 30 and substantially minimizing the conversion efficiency of a direct current component 30b when a conversion current of infrared rays 1 received by the reception part 2 is converted into the conversion voltage 30. COPYRIGHT: (C)2006,JPO&NCIPI
【課題】 送信部より所定のキャリア周波数のパルス状の赤外線を送信するとともに赤外線受光素子を備えた受信部で前記赤外線を受信し、前記受信部で受信した赤外線の変換電流を電圧変換部にて変換電圧に変換するとともに該変換電圧から前記キャリア周波数成分を周波数成分抽出手段にて抽出し、該キャリア周波数成分の大きさが規定値以下の場合に侵入者有りと判定する判定部を備えたものにおいて、受信部に外乱光として過度の光が赤外線受光素子に照射されても、受信部の変換電流を変換電圧に変換する際に電圧変換部にて変換電圧が飽和した状態となるのを抑えることができる赤外線防犯装置を提供する。 【解決手段】 受信部2で受信した赤外線1の変換電流を変換電圧30に変換する際に前記変換電圧30のキャリア周波数成分30aの変換効率を略最大とするとともに直流成分30bの変換効率を略最小に抑えるLC共振回路4を電圧変換部3に設けた。 【選択図】 図1




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