JP2006018480A - Infrared crime prevention device - Google Patents

Abstract

<P>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. <P>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. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an infrared crime prevention device that detects an intruder who is blocking infrared rays being transmitted and received.

  2. Description of the Related Art Conventionally, an infrared crime prevention device that detects an intruder by blocking infrared rays transmitted and received in a house exterior (see, for example, Patent Document 1).

  This is because the infrared light is regularly transmitted from the transmission unit and received by the reception unit including the infrared light receiving element, and when the infrared ray received by the reception unit falls below a predetermined value, the infrared light is transmitted by the intruder. It is provided with a determination unit that determines that there is an intruder by regarding that it is blocked.

  A phototransistor or a photodiode is used for the infrared light receiving element of the receiving unit. In such a conventional infrared security device, various light other than the infrared light from the transmitting unit is sent to the infrared light receiving element. For example, ambient light such as sunlight, outdoor lighting lamps, and car headlights may be incident and erroneously detected as infrared rays from the transmitter.

  Therefore, it has been considered to transmit pulsed infrared rays so that it can be distinguished from light (for example, sunlight) as a general disturbance. As shown in FIG. 5, this device transmits a pulsed infrared ray having a predetermined carrier frequency from a transmission unit, and receives the infrared ray by a receiving unit 2 (see FIG. 2) including an infrared light receiving element 20, and receives the infrared ray. The infrared conversion current received by the unit 2 is converted into a conversion voltage 30 (see FIG. 2) by the voltage conversion unit 3 comprising the load resistance R, and the conversion voltage 30 is amplified by the amplifier circuit 5 and its carrier frequency component 30a (see section (a) in FIG. 4) is extracted by the frequency component extraction means 6, and after this is shaped by the waveform shaping circuit 7, it is input to the determination unit 8 comprising a microcomputer or the like, and the magnitude of the carrier frequency component 30a When the value is equal to or less than the specified value, it is determined that there is an intruder on the assumption that the infrared ray transmitted from the transmission unit is blocked by the determination unit 8.

However, even in this case, when the infrared light receiving element 20 is irradiated with excessive light as disturbance light, the voltage measurement unit (see FIG. 5) generated in the voltage conversion unit 3 when the conversion current is converted from the reception unit 2 into the conversion voltage 30. 4), the conversion voltage 30 is saturated with the DC component 30b as shown in the section b of FIG. 4, and the frequency component extraction means 6 tries to extract the carrier frequency component 30a. It is buried in the saturated direct current component 30b and is not extracted and falls below the specified value, and the determination unit 8 determines that there is an intruder.
Japanese Utility Model Publication No. 1-133691

  The present invention has been made in view of the above points, and an object of the present invention is to transmit a pulsed infrared ray having a predetermined carrier frequency from a transmission unit and to transmit the infrared ray by a reception unit including an infrared light receiving element. The infrared conversion current received by the reception unit is converted into a conversion voltage by the voltage conversion unit, and the carrier frequency component is extracted from the conversion voltage by the frequency component extraction means. The magnitude of the carrier frequency component In the case where the presence / absence of an intruder is determined by the determination unit, when the receiving unit is irradiated with excessive light as disturbance light on the infrared light receiving element and the conversion voltage is saturated, it is erroneously detected that there is an intruder It is an object of the present invention to provide an infrared crime prevention device capable of preventing the above.

  In order to solve the above-mentioned problem, the invention according to claim 1 is an infrared security device that detects an intruder by blocking infrared rays 1 being transmitted and received, and has a predetermined carrier frequency from a transmitter. A pulsed infrared ray 1 is transmitted and the infrared ray 1 is received by a receiving unit 2 having an infrared light receiving element 20, and a conversion current of the infrared ray 1 received by the receiving unit 2 is converted into a conversion voltage 30 by a voltage conversion unit 3. A determination unit 8 that converts and extracts the carrier frequency component 30a from the converted voltage 30 by the frequency component extraction means 6 and determines that there is an intruder when the size of the carrier frequency component 30a is equal to or less than a specified value is provided. In this case, when the converted voltage 30 converted by the voltage conversion unit 3 is saturated, the saturation state is detected and it is not determined that there is an intruder, or it is deferred that there is an intruder. It is characterized in that comprising providing an intruder erroneous detection preventing means 4 consisting of low-pass filter 41 and the level determining circuit 42 of the fit.

  By adopting such a configuration, even if the receiving unit 2 is irradiated with excessive light as disturbance light on the infrared light receiving element 20, the conversion voltage 30 is saturated, and the magnitude of the carrier frequency component 30 a becomes equal to or less than a specified value. Intruder misdetection prevention means 4 detects the saturation of conversion voltage 30 so that determination unit 8 does not determine that there is an intruder or determines that there is an intruder, so there is no intruder. Nevertheless, it is possible to prevent erroneous detection that there is an intruder.

  In the present invention, even if the receiving unit is irradiated with excessive light as disturbance light on the infrared light receiving element, the conversion voltage is saturated and the magnitude of the carrier frequency component is less than the specified value, preventing intruder false detection Since the means detects the saturation of the conversion voltage and the determination unit does not determine that there is an intruder or suspends the determination that there is an intruder, false detection of the presence of an intruder despite the absence of an intruder Can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the infrared crime prevention device, a transmission unit and a reception unit are arranged with an interval in an exterior building or the like, and transmits infrared rays from the transmission unit and receives the infrared rays by a reception unit including an infrared light receiving element.

  As shown in FIG. 3, the infrared rays are transmitted from the transmitting unit as a rectangular pulsed infrared ray 1 having a predetermined carrier frequency, and the infrared ray receiving element 20 of the receiving unit 2 shown in FIG. Although the configuration of the transmission unit and the reception unit 2 is not particularly limited, in the present embodiment, the transmission unit irradiates the infrared rays emitted from the infrared LEDs toward the reception unit 2 with directivity through the lens. The pulsed infrared ray 1 transmitted from the transmitter may be either continuously irradiated as shown in FIG. 3 (a) or intermittently irradiated as shown in FIG. 3 (b). .

  The receiving unit 2 collects infrared rays from a range of a certain angle θ (deg) around the direction toward the transmitting unit through a condensing lens (not shown) on the infrared light receiving element 20. The infrared light receiving element 20 uses a phototransistor or a photodiode. In this embodiment, as shown in FIG. 2, an applied voltage of 5 V is applied to the phototransistor as the infrared light receiving element 20, and the infrared light receiving element 20 is used. An electric current is generated according to the amount of infrared rays applied to the.

  Then, as shown in FIG. 1, the conversion current of the infrared ray 1 received by the receiving unit 2 is converted into a conversion voltage 30 by the voltage conversion unit 3 (see FIG. 4), and the conversion voltage 30 is amplified by the amplifier circuit 5. After that, the carrier frequency component 30a (see section (a) in FIG. 4) is extracted by the frequency component extraction means 6, shaped by the waveform shaping circuit 7, and then input to the determination unit 8 composed of a microcomputer or the like. The determination unit 8 determines the presence or absence of an intruder based on the magnitude of the frequency component 30a. That is, when the carrier frequency component 30a of the converted voltage 30 falls below a specified value, it is considered that the infrared ray 1 transmitted from the transmission unit is blocked by the intruder, and it is determined that there is an intruder.

  Here, when excessive light as disturbance light is applied to the infrared light receiving element 20, the conversion voltage 30 is saturated with the DC component 30b as shown in section B of FIG. Even if it is attempted to extract the carrier frequency component 30a at 1), it is buried in the saturated direct current component 30b and is not extracted and falls below the specified value. However, in this case, the determination unit does not determine that there is an intruder. Or an intruder false detection prevention means 4 for holding the determination that there is an intruder.

  The intruder erroneous detection preventing means 4 includes a low-pass filter 41 and a level determination circuit 42, and the conversion voltage 30 from the voltage conversion unit 3 is input thereto. The input conversion voltage 30 is input to the low-pass filter 41 and low-passed (that is, passes a frequency component below a predetermined value (here, only approximately DC component)). Then, the DC component 30b of the converted voltage 30 that has been low-passed by the low-pass filter 41 is input to the level determination circuit 42, and a level determination is made as to whether or not the value is equal to or greater than a specified value (a value in a substantially saturated state). Transmit to unit 8.

  When the level determination circuit 42 determines that the DC component 30b is equal to or greater than the specified value, the conversion voltage 30 is considered to be saturated by the determination unit 8, and at this time the carrier frequency component 30a is equal to or less than the specified value, but an intruder It is determined that there is no intruder (it is not determined that there is an intruder) or that it is determined that there is an intruder.

  When the level determination circuit 42 determines that the DC component 30b is equal to or less than the specified value, the determination unit 8 considers that the converted voltage 30 is not saturated. At this time, if the carrier frequency component 30a is equal to or less than the specified value, the intrusion occurs. If the carrier frequency component 30a is equal to or greater than the specified value, it is determined that there is no intruder.

  Thus, by providing the intruder erroneous detection preventing means 4, excessive light as disturbance light is irradiated on the infrared ray receiving element 20 to the receiving unit 2, so that the conversion voltage 30 is saturated and the magnitude of the carrier frequency component 30 a. The intruder false detection prevention means 4 detects the saturation of the conversion voltage 30 even if becomes less than the specified value, and the determination unit 8 does not determine that there is an intruder or does not determine that there is an intruder. Therefore, it is possible to prevent erroneous detection that there is an intruder even though there is no intruder.

It is explanatory drawing of the whole structure of this embodiment. It is explanatory drawing of a receiving part and a voltage conversion part same as the above. The pulsed infrared rays transmitted from the transmission unit are shown. (A) is a time-series graph when transmitting continuously, and (b) is a time-series graph when transmitting intermittently. It is a figure which shows the converted voltage converted by the voltage conversion part same as the above. It is explanatory drawing of the conventional whole structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Reception part 20 Infrared light receiving element 3 Voltage conversion part 4 Intruder false detection prevention means 41 Low pass filter 42 Level determination circuit 5 Amplification circuit 6 Frequency component extraction means 7 Waveform shaping circuit 8 Determination part

Claims (1)

  An infrared crime prevention apparatus that detects an intruder by blocking infrared rays being transmitted and received, wherein the infrared rays are transmitted from a transmission unit to a pulsed infrared ray having a predetermined carrier frequency, and at the reception unit including an infrared light receiving element. The infrared conversion current received by the reception unit is converted into a conversion voltage by the voltage conversion unit, and the carrier frequency component is extracted from the conversion voltage by the frequency component extraction means, and the magnitude of the carrier frequency component is When the conversion voltage converted by the voltage converter is saturated, the saturated state is detected and the presence of an intruder is not determined. Or an intruder false detection prevention means comprising a low-pass filter and a level determination circuit for holding the determination that there is an intruder. Line security device.

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