JP3840504B2 - Intrusion detection sensor with countermeasures against light source interference - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an intrusion detection sensor including an opposing infrared sensor that is installed in a warning area such as a window of a building or a front door and used to detect an intruder.
[0002]
[Prior art]
As shown in FIG. 6, the conventional intrusion detection sensor includes a light projecting unit 50 including a light projector 51 that emits near-infrared IR that is a detection wave, and a light receiver 61 that receives near-infrared IR from the light projector 51. The light receiving unit 60 is provided, and each of the units 50 and 60 is arranged opposite to a warning area such as a building, and a warning line R composed of a beam-like near infrared IR is provided between the projector 51 and the light receiver 61. Set. And when this warning line R is interrupted by the intruder, an alarm is issued to detect the intruder. In order to ensure the reliability of the intrusion detection sensor, the light projecting and light receiving units 50 and 60 are respectively provided with a light projector 51 and a light receiver 61 across a plurality of upper and lower stages.
[0003]
[Problems to be solved by the invention]
However, in the intrusion detection sensors described above, the number of cases in which the warning function is disabled due to an obstruction is increasing in recent years. That is, as shown in FIG. 7, an intruder brings another infrared light source 70 and irradiates the near-infrared IR toward the light receiver 61, and the near-infrared light is emitted between the infrared light source 70 and the light receiver 61. When the IR light receiving state is created, no alarm is issued even if the warning line R between the projector 51 and the light receiver 61 is cut off. In particular, when the light projecting unit 5 of the same model as the intrusion detection sensor installed in the alert area is used as the infrared light source 70 that performs such a disturbing action, the disturbing action is surely successful.
[0004]
Therefore, an object of the present invention is to provide an intrusion detection sensor that can reliably detect the disturbing action when the disturbing action is as described above.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a pair of detection units arranged in opposition to each other, each detection unit having at least one projector and a light receiver, and its own projector and a counterpart light receiver. An intrusion detection sensor that sets a warning line consisting of a detection wave in a warning area between the detection unit and a detection wave received by at least one of the detection units is greater than the non-detection state of the intruder, and the other Interference recognition means for recognizing an obstruction action is provided when the variation amount of the difference from the detected light amount of the detection wave by the detection unit exceeds a predetermined level. The non-detection state refers to a normal light receiving state at the time of warning, that is, a state in which a detection wave is not blocked by an intruder.
[0006]
According to the above intrusion detection sensor, an intruder brings another infrared light source, irradiates the near infrared ray toward the light receiver of one detection unit, and detects a wave between the infrared light source and the light receiver. When a new light receiving state is newly created, the amount of light detected by the light receiver increases compared to the intruder non-detecting state. On the other hand, the received light amount of the detection wave at the light receiver disposed in the other detection unit does not change. In general, there is a slight difference between the amounts of light received by the light receivers of both detection units in the non-detection state of the intruder. Therefore, the difference in the amount of light received by the two light receivers greatly fluctuates due to irradiation with the other infrared light source. Thus, when the amount of light received by the light receiver on one side is greater than the non-detected state of the intruder and the fluctuation amount of the difference in the amount of light received by the two light receivers exceeds a predetermined level, the interference recognition means Judge that sabotage has occurred.
[0007]
In addition, when two infrared light sources are used to irradiate near-infrared rays toward the light receivers of the respective detection units, the amount of light received by the detected light at each of the light receivers is greater than the non-detected state of the intruder. To do. Moreover, when near infrared rays are radiated from each infrared light source to each detection unit, it is difficult to adjust the amount of light emitted from these infrared light sources so that the light reception levels of the light receivers of each detection unit are the same. The light reception balance by these light receivers is lost, and the difference between the light reception amounts of both light receivers is larger than the difference in the light reception amount in the non-detection state before the disturbing action is performed. Variations occur. Therefore, also in this case, the interference recognition means determines that an interference act has occurred. As described above, when one or both of the detection units perform a disturbing action, the disturbing recognition means judges the disturbing action. Therefore, by generating an alarm based on the judgment result, the occurrence of the disturbing action can be ensured. Can know.
[0008]
The one detection unit includes a superimposing unit that superimposes a light reception signal indicating a light reception amount of its own light receiver on a detection wave from its own light projector, and discriminates the light reception signal from the detection wave received by the other detection unit. It can be set as the structure provided with the discrimination means which detects the light reception amount of said one detection unit. In this way, by electrically connecting only the other detection unit to the control box, the light receiving unit and the discriminating means included in the other detection unit together with the amount of light received by the other detection unit. Since the amount of light received by the light receiver of the detection unit is also detected, wiring is simplified.
[0009]
In addition, one detection unit includes a transmission circuit that transmits a radio signal indicating the amount of light received by its own light receiver to the other detection unit, and the other detection unit includes a reception circuit that receives the radio signal, and the interference The recognizing means may be configured to recognize the disturbing action when the variation amount of the difference between the output signal of the light receiver of the other detection unit and the output signal of the receiving circuit is equal to or higher than a predetermined level. Even in this case, by electrically connecting only the other detection unit to the control box, the light receiving unit of the other detection unit and the light reception amount included in the other detection unit can be Since the amount of light received by the light receiver of this detection unit is also detected, wiring is simplified.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view schematically showing the intrusion detection sensor according to the first embodiment. The intrusion detection sensor includes first and second detection units 1 and 2 that are arranged opposite to a warning area such as the outside of a window A of a building. The first detection unit 1 is provided with a projector 11 that irradiates near-infrared IR, which is a detection wave, on the upper side thereof, and a light receiver 12 that receives near-infrared IR on the lower side thereof. Inside the detection unit 2, a light receiver 22 that receives near-infrared IR from the projector 11 of the first unit 1 is disposed on the upper stage side, and toward the light receiver 12 of the first detection unit 1 on the lower stage side. A projector 21 for irradiating near-infrared IR is provided. As a result, a warning line R composed of a beam-like near infrared IR is set between the projectors 11 and 21 and the light receivers 12 and 22 of the detection units 1 and 2.
[0011]
FIG. 2 is a block diagram of the intrusion detection sensor. As shown in the figure, on the output side of the light receivers 12, 22 of the first and second detection units 1, 2, the first and second light received that are output according to the amount of light received by each light receiver 12, 22 Amplifying circuits 31 and 32 for amplifying the signals a and b are connected, and disturbance recognition means 3 for recognizing the disturbing action is connected to the output sides of the amplifier circuits 31 and 32. The interference recognizing means 3 discriminates the amplified signals c and d amplified by the amplifier circuits 31 and 32, and at least of the first and second received light signals a and b output from the light receivers 12 and 22, respectively. The output signal e is output when one of the normal light receiving states, one of which is a non-detecting state, increases and the amount of fluctuation in the difference between the light receiving signals a and b is greater than a predetermined level set in advance. A determination circuit 33, a disturbance determination circuit 34 for determining that there has been a disturbing action based on the output signal e from the determination circuit 33, and a disturbance alarm output unit for issuing a warning by the disturbance detection signal f from the determination circuit 34 35. The interference recognition means 3, the intrusion detection circuit 4, the alarm output unit 5, and the amplifier circuits 31 and 32 are accommodated in a single control box.
[0012]
Further, an intrusion detection circuit 4 that operates when the warning line R in FIG. 1 is interrupted by an intruder is connected in parallel with the disturbance recognition means 3 on the output side of each of the light receivers 12 and 22. An alarm output unit 5 is connected to the output side of the intrusion detection circuit 4.
[0013]
Next, the operation of the above intrusion detection sensor will be described. When the intrusion detection sensor is turned on to enter the alert mode, an alert line R made of near infrared IR is formed between the first unit 1 and the second unit 2 in FIG. Here, in the non-detection state of the intruder, there is a slight difference between the amounts of light received by the light receivers 12 and 22 of both the detection units 1 and 2 shown in FIG. There is a difference. When the warning line R is interrupted by an intruder, the intrusion detection circuit 4 detects a decrease in the amount of light received by the light receivers 12 and 22 in both units 1 and 2 and outputs an intrusion detection signal. Based on this output, an alarm is issued from the alarm output unit 5 to notify the intruder.
[0014]
FIG. 3 is a front view for explaining a state of occurrence of an obstruction to the intrusion detection sensor. As shown in the figure, an intruder brings in another infrared light source 70 and irradiates the near infrared IR toward the second detection unit 2, for example, and the second detection unit 2 and the infrared light source 70 When a near-infrared IR light reception state is newly created, the amount of near-infrared IR received by the light receiver 22 on the second detection unit 2 side shown in FIG. Therefore, the level of the second light receiving signal b output from the light receiver 22 becomes higher. On the other hand, the amount of light received on the side of the light receiver 12 provided in the first detection unit 1 does not change, and the first light reception signal a output from this is a normal light reception level.
[0015]
The light reception signals a and b from the light receivers 12 and 22 are amplified by the amplification circuits 31 and 32 and output to the discrimination circuit 33 as amplification signals c and d. At this time, the second light reception signal b output from the light receiver 22 on the second detection unit 2 side is large, whereas the first light reception signal a output from the light receiver 12 on the first detection unit 1 side is Since it does not change, the level difference between the amplified signals c and d varies. When the fluctuation amount of the level difference is larger than a predetermined level set by the determination circuit 33 and the second light receiving signal b on the second detection unit 2 side becomes a certain level higher than a normal level. The output signal e is output from the determination circuit 33 to the determination circuit 34. Based on the disturbance detection signal f from the determination circuit 34, an alarm is issued from the alarm output unit 35 to notify the occurrence of an obstruction by an intruder. To do.
[0016]
Further, when the intruder irradiates the near-infrared IR with respect to the light receivers 12 and 22 of the first and second detection units 1 and 2 using the two infrared light sources 70, each of these light receivers. The amount of light received at 12 and 22 increases from the normal state, and the first and second light reception signals a and b output from the light receivers 12 and 22 become a certain level or more. In addition, when near infrared IR is irradiated to each of the detection units 1 and 2 from a separate infrared light source 70, the amount of light emitted from the infrared light source 70 is received by the light receivers 12 and 22 of the detection units 1 and 2, respectively. Since it is difficult to adjust the levels to be the same, the light reception balance at these light receivers 12 and 22 is lost, and the light reception amounts at the respective light receivers 12 and 22 are inevitably different. Between the first and second light receiving signals a and b, a level difference fluctuation of a predetermined level or more occurs. Therefore, also in this case, the determination circuit 33 determines that a disturbing action has occurred and issues an alarm from the alarm output unit 35.
[0017]
As described above, when a disturbing action is performed on one or both of the detection units 1 and 2, the disturbing action is judged and an alarm is issued, so that the occurrence of the disturbing action can be reliably detected.
[0018]
On the other hand, when there is no obstructive action by an intruder, the difference in the amount of light received from the light projectors 11 and 21 of the first and second detection units 1 and 2 and received by the light receivers 12 and 22 is constant. Therefore, the level difference does not fluctuate between the first and second light receiving signals a and b output from the light receivers 12 and 22.
[0019]
Also, fallen leaves or the like adhered to the cover of the first or second detection unit 1 or 2 and blocked one of the two warning lines R (FIG. 1) between the light projectors 11 and 21 and the light receivers 12 and 22. In this case, the amount of light received by the light receiving device 12 or 22 on the blocked side is reduced, so that the variation in the level difference between the received light signals a and b may be larger than the predetermined level set by the discrimination circuit 33. However, the received light signals a and b from the light receivers 12 and 22 do not increase from the normal state. Therefore, in these cases, the output signal e is not output from the discrimination circuit 33, and the alarm output unit 35 does not issue an alarm.
[0020]
Furthermore, even if the amount of light received by each of the light receivers 12 and 22 is affected by frost, fog, rain, dirt on the cover, etc., the influence of these is exerted on the respective light receivers 12 and 22 to the same extent. The fluctuation amount of the difference between the light reception signals a and b becomes a predetermined level or less, and no alarm is issued from the alarm output unit 35. Therefore, it is possible to prevent a false alarm from being issued.
[0021]
FIG. 4 is a block diagram showing a second embodiment of the present invention. The intrusion detection sensor shown in the same figure shows the amount of received light when the amount of light received by its own light receiver 12 exceeds a predetermined level to the drive circuit 13 that drives the projector 11 provided in the first detection unit 1. Superimposing means 6 is provided for superimposing the first received light signal a shown on the near-infrared IR irradiated from its projector 11.
[0022]
On the second detection unit 2 side, the first received light signal a is discriminated from the second received light signal b based on the received light amount at the light receiver 22 to detect the received light amount on the first detection unit 1 side. Discriminating means 7 is provided. The discriminating means 7 includes an amplifying circuit 70 that amplifies the signal from the light receiver 22, the frequency of the superimposed first light receiving signal a from the amplified signal, and the reception of the near-infrared IR from the first light projector 11. A frequency discriminating circuit 71 for discriminating the frequency of the second light receiving signal b indicating the quantity and detecting the first and second light receiving signals a and b; and both light receiving signals connected to the output side of the frequency discriminating circuit 71 There are provided first and second level detection circuits 72 and 73 for detecting the respective levels (amount of received light) of a and b. The outputs of both level detection circuits 72 and 73 are input to the interference recognition means 3 and processed in the same manner as in the first embodiment.
[0023]
According to the above configuration, the near-infrared IR from the light projector 21 of the second detection unit 2 is received by the light receiver 12 of the first detection unit 1, and the first light reception signal a indicating the amount of light received is the first detection unit. The superimposing means 6 provided on the 1 side superimposes on the near infrared IR irradiated from its own projector 11 and irradiates it toward the light receiver 22 of the second detection unit 2. On the other hand, on the second detection unit 2 side, of the received light amount of near infrared IR received by its own light receiver 22 by the frequency discriminating circuit 71 of the discrimination means 7, the light receiver 22 on the second detection unit 2 side. A second received light signal b indicating the received light amount and a first received light signal a indicating the received light amount of the light receiver 12 on the first detection unit 1 side are discriminated. The levels of the discriminated first and second light reception signals a and b are detected by first and second level detection circuits 72 and 73, respectively. Here, when the level (light receiving amount) of at least one of the light receiving signals a and b is larger than that in the normal light receiving state, and the fluctuation amount of the difference between the light receiving signals a and b becomes a predetermined level or more, As in the case described above, the alarm output unit 35 issues an alarm by the output from the interference determination circuit 34.
[0024]
In this way, since only one of the second detection units 2 needs to be electrically connected to the control box, wiring is simplified.
[0025]
In the third embodiment of the present invention, the amount of light received by the light receiver 12 of the first detection unit 1 (first light reception signal a) is transmitted to the second detection unit 2 side as a radio signal, and the second detection unit 2 is transmitted. To receive the radio signal. That is, as shown in FIG. 5, the first detection unit 1 is provided with a transmission circuit 41 that transmits the first light reception signal a, which is the output signal of the light receiver 12, to the second detection unit 2 as a radio signal aa. The second detection unit 2 is provided with a receiving circuit 42 that receives the radio signal aa. The interference recognizing means 3 passes through the amplifier circuits 31 and 32, the second light receiving signal b which is the output signal of the light receiver 22 of the second detection unit 2, and the first light receiving signal a which is the output signal of the receiving circuit 42. In the same manner as in the first embodiment, when the amount of fluctuation in the level difference between the two light reception signals a and b is equal to or greater than a predetermined level, the disturbing action is recognized. As the wireless signal, it is preferable to use a signal in a radio frequency region far from the near infrared region.
[0026]
This configuration also simplifies wiring because only one of the second detection units 2 needs to be electrically connected to the control box, as in the second embodiment.
[0027]
Note that a wired signal may be used instead of the wireless signal in the third embodiment of FIG. In that case, there is no advantage that the wiring is simplified.
[0028]
In the above embodiment, one projector 11 and 21 and two light receivers 12 and 22 are arranged in the first and second detection units 1 and 2, respectively, but two or more projectors and light receivers are arranged in each unit. May be.
[0029]
【The invention's effect】
As described above, according to the intrusion detection sensor of the present invention, the disturbing action of disabling the warning function by irradiating the detection unit using another infrared light source is reliably detected.
[Brief description of the drawings]
FIG. 1 is a schematic front view showing an intrusion detection sensor according to the present invention.
FIG. 2 is a block diagram showing an electric circuit of the intrusion detection sensor according to the first embodiment of the present invention.
FIG. 3 is a front view for explaining the state of occurrence of an obstruction to the intrusion detection sensor.
FIG. 4 is a block diagram showing an electric circuit of an intrusion detection sensor according to a second embodiment of the present invention.
FIG. 5 is a block diagram showing an electric circuit of an intrusion detection sensor according to a third embodiment of the present invention.
FIG. 6 is a schematic front view showing a conventional intrusion detection sensor.
FIG. 7 is a front view for explaining a state of occurrence of an obstruction to the intrusion detection sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,2 ... Detection unit 11,21 ... Light projector, 12, 22 ... Light receiver, 3 ... Interference recognition means, 6 ... Superimposition means, 7 ... Discrimination means, IR ... Detection wave (near infrared), R ... Warning line.

Claims (3)

It has a pair of detection units arranged opposite to each other, and each detection unit has at least one projector and receiver, and consists of a detection wave in a warning area between its own projector and the other receiver. An intrusion detection sensor for setting a warning line,
When the amount of light detected by at least one detection unit is greater than the intruder's non-detection state, and the amount of variation in the difference between the amount of light detected by the other detection unit is greater than or equal to a predetermined level, An intrusion detection sensor equipped with a means for recognizing obstructions. The detection unit according to claim 1, wherein one detection unit includes a superimposing unit that superimposes a light reception signal indicating the amount of light received by the own light receiver on a detection wave from the own projector, and the light reception signal is detected from the detection wave received by the other detection unit. An intrusion detection sensor provided with discrimination means for discriminating between and detecting the amount of light received by the one detection unit. 2. The transmission circuit according to claim 1, wherein one detection unit includes a transmission circuit that transmits a radio signal indicating the amount of light received by its own light receiver to the other detection unit, and the other detection unit includes a reception circuit that receives the radio signal. The interference recognition means is an intrusion detection sensor for recognizing an interference action when a variation amount of a difference between the output signal of the light receiver of the other detection unit and the output signal of the reception circuit becomes a predetermined level or more.

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