JP3840502B2 - Security sensor with interference detection function using stray light - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a security sensor using a passive infrared element (hereinafter referred to as “PIR element”) and having a function of detecting an obstruction.
[0002]
[Prior art]
The intruder detection system using the security sensor is configured such that the PIR element receives infrared rays from the human body in the detection area and detects the intruder from the difference between the human body and the ambient temperature.
[0003]
By the way, in order to disturb the operation of the intruder detection system, a paper tape is pasted on the front surface of the security sensor or a white paint is applied during a non-warning operation in which a person enters and exits the room where the security sensor is installed. There is a case where a security sensor cannot detect a human body by performing an obstructing action to be applied by spraying and may enter the room during a warning operation in which a person does not enter or exit.
[0004]
FIG. 8 is a diagram showing a change characteristic of detection sensitivity of the PIR sensor 7 when the white paint is applied to the front surface of the cover 5 by replacing the thickness of the applied white paint with the spray time. Yes. The detection sensitivity (difference between the temperature of the human body and the room temperature) shown on the vertical axis when there is no obstruction is higher than 2 ° C. as shown in the characteristic A. The horizontal axis represents the target speed (moving speed of the intruder). The detection sensitivity when the white paint was applied by spraying for 4 seconds decreased to about 5 ° C. as shown in the characteristic B, and the detection sensitivity when applied by spraying for 8 seconds was reduced to about 14 ° C. Generally, since the PIR sensor 7 is required to have a detection sensitivity higher than 4 ° C., the detection function is impaired by spraying for about 4 seconds.
[0005]
A security sensor provided with a radiant energy detection device that detects the presence or absence of a masking object (hereinafter referred to as “interfering object”) that impairs the detection function of the security sensor when such a disturbing action is performed. No. 287278.
[0006]
This radiant energy detection device is provided with a light emitting element that emits infrared light or visible light and a light receiving element that receives the reflected light in a security sensor, and the reflected light from the inner surface of the cover is reflected by an obstacle outside the cover. By detecting that the amount of light incident on the light receiving element increases due to the addition of the reflected light, it is configured to detect that there is a shield on the outside of the cover.
[0007]
[Problems to be solved by the invention]
The radiant energy detection device has a large amount of stray light reflected on the inner surface of the cover and a large amount of light incident on the light receiving element. Therefore, the reflected light from the fingers and instruments of the disturbing person's hand and the reflected light from the shield It is difficult to detect the increase.
[0008]
The present invention has been made for the purpose of solving the above-mentioned problems, and when a disturbance action is performed during the operation of the disturbance detection function, it can be detected immediately. The object is to obtain a security sensor with a disturbance detection function that can detect the presence of an obstruction when there is an obstacle such as white paint or paper tape.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a security sensor in which a passive infrared detection element and an optical system for setting the detection area thereof are covered with a cover. First and second disturbance detection means are provided, the first disturbance detection means is a first projector that emits a first detection light beam, and the first detection light beam is at or near the outer surface of the cover. A first light receiver that receives the reflected light reflected by the obstruction in the light source, and the stray light that is disposed between the light projector and the light receiver and is reflected by the inner surface of the cover is prevented from entering the light receiver. And the second disturbance detection means includes a second projector that emits a second detection light beam, and an obstruction that the second detection light beam adheres to the cover inner surface and the cover. The second receiver that receives the stray light reflected by And a vessel.
[0010]
According to this configuration, since the stray light reflected from the inner surface of the first detection light beam emitted from the first projector is blocked by the shielding member, it is incident on the first and second light receivers. Instead, the reflected light from the obstruction outside the cover is incident on the first light receiver.
Further, the stray light reflected from the inner surface of the cover of the second detection light beam emitted from the second projector is blocked by the shielding member and does not enter the first light receiver, but enters the second light receiver. The stray light in which the second light beam for detection from the second projector is reflected on the inner surface of the cover and the stray light in which the reflected light from the obstacles attached to the outer surface of the cover is reflected on the inner surface of the cover are incident.
Accordingly, the second disturbance detection means can detect the obstruction and the obstruction at a position slightly away from the security sensor, and the first disturbance detection means can reliably detect the obstruction on the outer surface of the cover.
[0011]
Further, in a preferred embodiment of the present invention, the first and second disturbance detection means detect the reflected light from the outside of the cover and the stray light in the cover with one projector and two receivers. It is configured.
According to this configuration, the first light receiver detects the reflected light of the first detection light beam emitted outward from the projector through the cover, and the second light receiver receives the second detection light beam. The stray light reflected on the inner surface of the cover and the reflected light from the obstructions attached to the outer surface of the cover are detected.
[0012]
Furthermore, in a preferred embodiment of the present invention, the first and second disturbance detection means detect the reflected light from the outside of the cover and the stray light in the cover with two projectors and one receiver. It is configured.
According to this configuration, the reflected light of the first detection light beam emitted outward from the first projector through the cover and the second detection light beam emitted from the second projector with one light receiver. Detects stray light reflected on the inner surface of the cover and stray light reflected on the inner surface of the cover by the light reflected by the obstructions attached to the outer surface of the cover.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
1 is a plan view of a security sensor according to an embodiment of the present invention, FIG. 2 is a partially cutaway side view as seen from the direction of arrow II in FIG. 1, and FIG. 3 is from the direction of arrow III in FIG. FIG.
In FIG. 2, the security sensor 1 is formed of white high-density polyethylene so that the mounting base 3 attached to the ceiling surface 2, the sensor main body 4 attached to the mounting base 3, and the internal structure cannot be seen. A cover 5 is provided. The sensor body 4 includes a circuit board 6, a PIR sensor 7 for detecting a human body supported by the circuit board 6 via a bracket 40, and an active infrared sensor (hereinafter referred to as “AIR sensor”) for detecting obstructions. 8 and. The PIR sensor 7 includes a PIR element 9 that operates in response to far-infrared rays, a polyhedral reflecting mirror 10 that forms a plurality of detection areas A, and a sensor board that is electrically connected to the circuit board 6 via a connection cord 41. 42, and a detection circuit is mounted on the sensor substrate 42. The PIR element 9, the multi-surface reflecting mirror 10 and the sensor substrate 42 are accommodated in a housing 43, and the housing 43 is attached to the bracket 40.
[0014]
The AIR sensor 8 includes a first projector 11 (common to the second projector) that emits a first detection light beam e1 (common to the second detection light beam) made of near infrared rays, and a cover 5. The first light receiver 12 (FIG. 3) that receives the reflected light r that is reflected by the obstruction outside the cover and returned through the cover 5, and the one of the emitted light. The unit includes a second light receiver 13 that receives the stray light m reflected by the inner surface of the cover 5. The stray light m here refers to light reflected by the inner surface of the cover 5 and light entering the inside of the cover 5 after being reflected by the inner surface of an obstruction adhered to the outer surface of the cover, which will be described later.
[0015]
As shown in FIG. 1, the first projector 11 and the first light receiver 12 are arranged on the back side of the multi-faced reflecting mirror 10, and the optical axis of the PIR sensor 7 is shown in FIG. 2. It is attached to the circuit board 6 by being inclined so as to face the human body detection area A, and a shielding member 14 formed of a vertical foamed synthetic resin is provided between the circuit board 6 and the back surface of the bracket 40 and the cover. It arrange | positions so that between the inner surfaces of 5 may be plugged up. The second light receiver 13 is attached to the circuit board 6 in a direction in which sunlight or light of a headlight of an automobile does not enter the side of the first projector 11, and a cylindrical hood 15 is attached. The cover 5 is configured to receive less light than the stray light m that has been reflected multiple times.
[0016]
Further, the detection sensitivity of the first light receiver 12 does not detect the reflected light from the floor surface, but detects the reflected light r from a human body or a metal instrument within a range of several tens of centimeters from the AIR sensor 8. Thus, the amount of light emitted from the first projector 11 and the detection sensitivity of the first light receiver 12 are set.
Further, the detection sensitivity of the second light receiver 13 is based on the incident light amount when only the reflected light (stray light) from the inner surface of the cover 5 is used as a reference value, and when the incident light amount increases by a predetermined amount from the reference value, an obstruction The detection sensitivity is set so that a detection signal is output.
[0017]
FIG. 4 is a block circuit diagram of the security sensor. First, the detection operation of the PIR sensor 7 will be described.
In FIG. 4, when a human body enters the human body detection area A, the PIR element 9 detects far infrared rays emitted from the human body and detects the human body from the difference between the human body and the ambient temperature. The amplifier 21 amplifies the detection signal input from the PIR element 9, and the comparator 22 outputs a human body detection signal when the level of the input signal from the amplifier 21 exceeds a threshold value. The microcomputer 23 having a built-in CPU sends a human body detection signal h indicating that there has been an intruder to the output circuit 24 when the human body detection signal is input, and the output circuit 24 has a predetermined format, for example, a continuous sound. An alarm command signal for transmitting an alarm is transmitted to an external control panel.
[0018]
The AIR sensor 8 constitutes a first obstruction detection means 17 and a second obstruction detection means 18, and the first obstruction detection means 17 includes the first projector 11 and the first light reception. It comprises a generator 12, a pulse generator 25, a gate 26a, an amplifier 27a, and a comparator 28a. The second obstacle detection means 18 includes a second light receiver 13, a pulse generator 25, a gate 26b, an amplifier 27b, and a comparator 28b.
[0019]
Next, the obstruction detection operation of the first obstruction detection means 17 will be described. The pulse signal output from the pulse generator 25 is input to the first projector 11, and the pulsed near-infrared first detection light beam e <b> 1 is emitted downward through the cover 5 from the first projector 11 of FIG. 2. The A part of the emitted light e1 is reflected on the inner surface of the cover 5 and further irregularly reflected in the cover 5 to become stray light m. However, the amount of light incident on the first light receiver 12 is absorbed by the shielding member 14 and is small. It is comprised so that it may become.
[0020]
In the state as described above, when the disturbing person approaches the cover 5, the reflected light r from the finger or instrument of the hand enters the first light receiver 12 through the cover 5, and the first light receiver 12. 4 is input to the amplifier 27a after the noise component is removed by selecting only the component having the same frequency as that of the emitted light by the gate 26a in FIG. 4, and the level of the amplified signal is the first by the comparator 28a. Compared to threshold. The threshold value is set in advance to a value lower than the level of the amplified signal when the finger or instrument of the hand approaches within a predetermined distance from the cover 5, and the comparator 28a has the input signal of the first threshold value. The first obstruction detection signal s1 is output to the microcomputer 23, the microcomputer 23 outputs a trouble signal a to the output circuit 24, and the output circuit 24 generates an alarm in a mode different from the human body detection alarm. For example, an alarm command signal for issuing an intermittent sound alarm is transmitted to an external control panel.
[0021]
Next, when the obstacle 16 sprayed with white paint is attached to the front surface (outer surface) of the cover 5 in FIG. 2, the first detection light beam e <b> 1 is reflected by the obstacle 16, The stray light m is remarkably increased and is incident on the second light receiver 13 of the second obstacle detection means 18 in FIG. The second photoreceiver 13 outputs this detection signal to the gate 26b, the noise component is removed by the gate 26b and is input to the amplifier 27b, and the output of the amplifier 27b is compared with the second threshold value by the comparator 28b. . The threshold value is set to a value higher than the output level of the amplifier 27b when there is no obstruction 16, and the comparator 28b detects the second obstruction when the input signal exceeds the second threshold value. The signal s2 is output to the microcomputer 23, the microcomputer 23 outputs the trouble signal a to the output circuit 24, and the output circuit 24 externally outputs an alarm command signal for sending out the alarm in the same manner or different from the above-mentioned alarm. To the control panel.
[0022]
In addition, when the obstruction 16 is like a blank sheet placed at a position slightly away from the security sensor 1, the first obstruction detection means 17 is a quantity of the reflected light r incident on the first light receiver 12. Increases, so that obstructions can be detected. However, the second obstacle detection means 18 cannot detect the stray light m incident on the second light receiver 13 because the amount of the stray light m is small. Further, when the obstruction 16 is a white paint reflecting near infrared rays attached to the outer surface of the cover 5 of the security sensor 1 or dirt adhering in a kitchen or the like, the first obstruction detection means 17 Since the amount of the reflected light r incident on the light receiver 12 does not increase, an obstruction cannot be detected. However, the second obstacle detection means 18 can detect the stray light m incident on the second light receiver 13 because the amount of the stray light m increases.
As described above, the AIR sensor 8 according to the present embodiment is configured such that the disturbing person's hand fingers and instruments, white paper and other obstructions located slightly away from the cover 5, and white attached to the front surface of the cover 5. Interferences such as paint and oil stains can be detected.
[0023]
FIG. 5 is a plan view of a security sensor according to another embodiment sharing the first and second light receivers, and FIG. 6 is a rear view seen from the VI direction in FIG. The same reference numerals indicate the same or corresponding parts. In FIG. 5, reference numeral 19 denotes a second light projector, which is disposed on the first light receiver 12 (common to the second light receiver) between which the first light projector 11 and the shielding member 14 are sandwiched. As shown in FIG. 2, the optical axis is slightly downward from the horizontal direction, and the second detection light beam e2 from the second projector 19 does not directly enter the first light receiver 12, and the cover The light reflected by the inner surface of 5, the side surface of the multi-faced reflecting mirror 10, etc. is also installed in a direction that does not directly enter the first light receiver 12.
The position and emission direction of the second projector 19 are such that when white paint or the like is sprayed on the outer surface of the cover 5, the reflected light m increases the stray light m in the cover 5 and enters the first light receiver 12. The amount of stray light m is set to increase.
[0024]
FIG. 7 is a block circuit diagram of this embodiment, and the same reference numerals as those in FIG. 4 indicate the same or corresponding parts. The AIR sensor 8 of the present embodiment constitutes a first obstruction detection means 17 and a second obstruction detection means 18, and the first obstruction detection means 17 includes the first projector 11, the first obstruction detection means 17. 1 light receiver 12, pulse generator 25, gate 26 a, amplifier 27 a, comparator 28 a, and changeover switch 29. The second obstacle detection means 18 includes a second projector 19, a first light receiver 12, a pulse generator 25, a gate 26 a, an amplifier 27 a, a comparator 28 b, and a changeover switch 29.
[0025]
Since the operation of the PIR sensor 7 of this embodiment is the same as that of the above embodiment, the description thereof is omitted.
Next, the obstruction detection operation of the first obstruction detection means 17 and the second obstruction detection means 18 will be described. The pulse signal output from the pulse generator 25 is input to the changeover switch 29, the gate 26, and the comparators 28a and 28b. The changeover switch 29 causes the first projector 11 and the second projector 19 to alternately project at intervals of a few seconds, and the first light receiver 12 causes the first light beam e1 from the first projector 11 to be projected. The reflected light r from the obstruction at a position away from the outer surface of the cover 5 and the reflected light from the inner surface of the cover 5 and the reflected light from the obstruction 16 of the second detection light beam e2 from the second projector 19. Stray light m due to is incident alternately. The stray light due to the reflected light from the inner surface of the cover 5 of the first detection light beam e <b> 1 is blocked by the shielding member 14 and hardly enters the first light receiver 12.
[0026]
The two output signals of the first light receiver 12 are alternately input to the gate 26, the noise component is removed and input to the amplifier 27, and the amplified signal r1 of the reflected light r is the first comparator 28a and stray light m. The amplified signal m1 is compared by the second comparator 28b as follows. The first comparator 28a compares the amplified signal r1 with the first threshold value, and the second comparator 28b compares the amplified signal m1 with the second threshold value. When it is larger, the disturbance detection signals s1 and s2 are output to the microcomputer 23, the microcomputer 23 outputs the trouble signal a to the output circuit 24, and the output circuit 24 sends an alarm command signal to the external control panel.
[0027]
According to the above configuration, the first obstacle detection means 17 and the second obstacle detection means 18 can be constituted by the two projectors 11 and 19, the one light receiver 12 and the one amplification system. The configuration is simpler than that of the first embodiment.
[0028]
In the above embodiment, the two comparators 28a and 28b are provided. However, the threshold value of one comparator may be switched between the first and second threshold values using a pulse signal.
[0029]
In the first and second embodiments, the first obstruction detection means and the second obstruction detection means are configured by one projector and two light receivers, or two projectors and one light receiver. Unlike these, it is good also as a structure provided with 2 sets of light projectors and light receivers, respectively.
[0030]
Moreover, in the said Embodiment 1, 2, although the security sensor was attached to the ceiling surface, you may attach to a wall surface.
[0031]
In addition, in a security sensor installed in a kitchen or the like, oil droplets or the like adhere to the outer surface of the cover and become dirty, and the detection sensitivity of the PIR sensor tends to decrease. In order to compensate for such a decrease in sensitivity, as indicated by a broken line in FIG. 4, the PIR sensor 7 increases as the detection signal level of the second light receiver 13 that detects the stray light m in the cover 5 gradually increases. An amplification factor control means 30 for gradually increasing the amplification factor of the amplifier 21 may be provided to maintain the detection sensitivity of the PIR sensor 7 at a constant level.
[0032]
【The invention's effect】
According to the present invention, in the security sensor in which the passive infrared detection element and the optical system for setting the detection area are covered with the cover, the first detection light beam is emitted outside the detection area through the cover. Receiving the reflected light from the obstacle of the detection beam and detecting the obstacle in comparison with the first threshold, and receiving only the stray light in the cover; Since there is a second obstacle detection means for detecting an obstacle in comparison with the second threshold value, there is no decrease in detection accuracy due to stray light in the cover of the passive infrared detection element, In addition, it is possible to reliably detect various interferences that reflect the detection light such as interference actions and white paint.
[Brief description of the drawings]
FIG. 1 is a plan view of a security sensor according to an embodiment of the present invention.
2 is a partially cutaway side view seen from the direction of arrow II in FIG.
FIG. 3 is a rear view seen from the direction of arrow III in FIG.
FIG. 4 is a block circuit diagram of a security sensor according to the present embodiment.
FIG. 5 is a plan view of a security sensor according to another embodiment of the present invention.
6 is a rear view seen from the direction of arrow VI in FIG.
FIG. 7 is a block circuit diagram of a security sensor according to another embodiment of the present invention.
FIG. 8 is a diagram showing detection sensitivity characteristics due to obstructions of a PIR sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Security sensor, 2 ... Ceiling surface, 3 ... Mounting base, 4 ... Sensor main body, 5 ... Cover, 6 ... Circuit board, 7 ... PIR sensor, 8 ... AIR sensor, 9 ... PIR element, 10 ... Polyhedral reflector, DESCRIPTION OF SYMBOLS 11 ... 1st light projector, 12 ... 1st light receiver, 13 ... 2nd light receiver, 14 ... Shielding member, 16 ... Obstruction, 17 ... 1st obstruction detection means, 18 ... 2nd obstruction Detection means, 19 ... second projector, 23 ... microcomputer, 24 ... output circuit, 30 ... gain control means, 40 ... bracket, 41 ... connection cord, 42 ... sensor substrate, A ... human body detection area, e1 ... first 1 detection light beam, e2 ... second detection light beam, m ... stray light, r ... reflected light.

Claims (3)

In a security sensor in which a passive infrared detector and an optical system for setting its detection area are covered with a cover,
First and second disturbance detection means are provided outside the detection area in the cover, and the first disturbance detection means emits a first light beam for detection, and the first A first light receiver that receives reflected light reflected by an obstruction on the outer surface of the cover or in the vicinity thereof, and the light beam for detection is disposed between the projector and the light receiver. A shielding member that prevents the stray light reflected by the light from entering the light receiver,
The second disturbance detection means receives a second projector that emits a second detection light beam, and a stray light that is reflected by the obstruction attached to the inner surface of the cover and the cover. A security sensor comprising two light receivers. The security sensor according to claim 1, wherein the first and second projectors are common. The security sensor according to claim 1, wherein the first and second light receivers are common.

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