JPH11250362A - Crime prevension sensor with disturbance detection function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide crime prevention sensor with an obstruction detection function that can easily detect existence of the detection function obstruction when the front side of a lens or a cover is coated with a transparent paint or the like. SOLUTION: The device is equipped with a body A having an infrared detection element 4, a lens 6 or a cover fitted to this body A, a light guiding material 8 that has a front side 8a forming part of its outside surface, an incident plane 8f on one end and a light emitting surface 8g on the other end, a light projecting element 11 for projecting a light inside of the light guiding material 8 from the incident plane 8f, a light receiving element 12 for receiving a projected light beam through the light emitting surface 8g, and a detection circuit 15 for detecting adherence of an obstruction to the front side 8a. The front side 8a of the light guiding material 9 is made to transmit part of the projected light beam outward the light guiding material 8 and other part of it is formed into a ground glass shape on which many small projecting and recessing parts are formed for reflecting the light beam inward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a security sensor using a passive infrared detecting element (hereinafter, referred to as "PIR element") and having a function of detecting an operation disturbance of the PIR element.

[0002]

2. Description of the Related Art An intruder detection system using a security sensor is configured such that a PIR element receives infrared rays from a human body in a detection area and detects an intruder from the difference between the human body and the ambient temperature. .

By the way, in order to hinder the operation of the intruder detection system, far-infrared rays pass through the front surface of the cover of the security sensor during non-alarm operation in which many people enter and exit the room where the security sensor is installed. There is a case where the security sensor cannot detect the human body by attaching a transparent paint, an adhesive tape, or the like that is not used, and may enter a room at the time of a warning operation in which a person stops coming and going.

Japanese Patent Laid-Open Publication No. 2-287278 discloses a security sensor provided with a radiant energy detecting device for detecting the presence or absence of a masking object (hereinafter, referred to as an "interfering object") which interferes with the detection function of the security sensor. Have been.

This radiant energy detecting device comprises a light emitting element for emitting near-infrared light or visible light toward an inner surface of a portion of a security sensor cover through which far-infrared rays from a human body pass, and a near-infrared light from the inner surface of the cover. And a light receiving element that receives the reflected light of the
By detecting the amount of increase in the amount of light incident on the light receiving element due to the addition of reflected light from the obstruction applied to the outer surface of the cover, it is configured to detect that there is an obstruction on the outer surface of the cover. I have.

[0006]

The radiant energy detecting device has a large amount of near-infrared light reflected on the inner surface of the cover and hence a large amount of light incident on the light receiving element, but a small amount of light reflected from an obstacle. However, it is difficult to detect the increase due to the reflected light from the obstacle. In addition, if the front of the cover is sprayed with a transparent paint that shields far-infrared rays and transmits visible light to near-infrared light, or a black paint that absorbs far-infrared rays to visible light, this obstruction will prevent Since the amount of reflected light is even smaller, it is more difficult to detect obstacles, especially in the case of the transparent paint, which cannot be visually identified,
Obstacle detection becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended that when an obstruction such as a transparent paint or an adhesive tape adheres to the front surface of a cover of a security sensor, the problem is solved. It is an object of the present invention to obtain a security sensor with an obstacle detection function that can easily detect the presence of an obstacle.

[0008]

In order to achieve the above object, a security sensor with an obstacle detecting function according to the present invention comprises a main body having an infrared detecting element, and a main body mounted on the main body and detecting the infrared detecting element. A lens that sets an area or a cover that covers the infrared incident surface side of the infrared detecting element, a front surface that forms a part of the outer surface of the lens or the cover, a light guide member that has an incident surface at one end and an exit surface at the other end, A light emitting element that projects light from the incident surface to the inside of the light guide member, and a light receiving element that receives the projected light beam through the emission surface,
A detection circuit for detecting the adhesion of an obstruction to the front surface based on the amount of light received by the light receiving element, and a part of the projected light beam on the front surface of the light guide member. In this case, a large number of irregularities are formed to transmit light to the outside and reflect other parts inward.

[0009] According to the above-mentioned structure, since the obstruction such as the transparent paint or the adhesive tape adheres to the outer surface of the lens or the cover, the many irregularities on the front surface of the light guide member have the obstruction itself or the obstruction. Filled with adhesive. As a result, when the obstruction is transparent or a light color such as white, the light enters the obstruction from the front of the light guide member, is reflected by the obstruction, and the amount of light received by the light receiving element increases. Is black or dark, light is incident on the obstruction from the front surface of the light guide member and then absorbed in the obstruction, so that the amount of light received by the light receiving element is reduced. The detection circuit detects the presence or absence of the obstacle by comparing the amount of light received by the light receiving element with a threshold. In addition, objects that temporarily adhere to the lens or the cover, such as insects, are not obstructions, but the irregularities are not buried depending on the insects, so that the amount of light received by the light receiving element increases or decreases and the insects are erroneously detected as obstructions. There is no danger.

[0010] In a preferred embodiment of the present invention, the light guide member is curved from the incident surface to the exit surface, whereby light beams emitted from the light projecting element are inside the front surface. Is set so that only the reflected light reflected by the light enters the light receiving element. According to the above configuration, only the light reflected from the front surface of the light guide member is incident on the light receiving element, so that the light received by the light receiving element when the paint adheres to the unevenness on the front surface is received. The change in volume is large.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a perspective view of a security sensor according to one embodiment of the present invention. The security sensor 1 includes a main body A having a base 2 attached to a wall surface and a case 3 covering a front surface of the base 2 and a pyroelectric element 4 as a passive far-infrared detecting element housed in a main body A. I have. The case 2 is fixed to the base 2 with a screw (not shown).

FIG. 2 is a longitudinal sectional view of the security sensor 1 taken along the line II-II in FIG. 1, and FIG. 3 is a transverse sectional view taken along the line III-III in FIG. As shown in FIG. 2, the pyroelectric element 4 of the case 3
A lens for setting a detection area is fitted in a portion covering the front of the camera. This lens 6 also has a function as a cover for protecting the pyroelectric element 4 by covering the front surface of the pyroelectric element 4 which is an infrared incident surface, so that far infrared rays are transmitted and the inside of the security sensor 1 is not visible. A lens portion 7 formed of a synthetic resin such as a flexible polyethylene colored in milky white or the like and having a Fresnel lens forming a detection area of the pyroelectric element 4, and provided near the lens portion 7. And a mounting groove 9 into which a light guide member 8 described later is fitted. The pyroelectric element 4 detects intrusion of a human body into the detection area by detecting far-infrared rays emitted from the human body in the detection area.

As shown in the perspective view of FIG. 4, the light guide member 8 is formed of an acrylic resin or the like which transmits a detection wave, which will be described later, for example, near infrared rays. It is formed in a gate shape having pillar portions 8d and 8e, and its cross-sectional shape is substantially triangular as shown in FIG. The front surface 8a of the curved portion 8c has a shape along the front surface of the lens 6, and as shown in FIG. 3, has many small irregularities and is in the form of ground glass. The back surfaces 8b, 8b of the curved portion 8c are smooth surfaces, and when it is necessary to increase the reflectance, as shown in FIG. 5, a reflective film 8 such as an Al film applied by a method such as sputtering.
h may be formed. The end surfaces of the column portions 8d and 8e shown in FIG. 4 are smooth surfaces, and form the entrance surface 8f and the exit surface 8g, respectively.

Further, as shown in FIG.
A near-infrared light emitting element (hereinafter, referred to as “light emitting element”) 11 that is mounted on the substrate 10 and generates near-infrared light that is a detection wave is opposed to the incident surface 8f, and the emitting surface 8g is The light receiving elements 12 mounted on the substrate 10 face each other. The pyroelectric element 4 is also mounted on the substrate 10. The light projecting element 11 is driven by a driving circuit 13 to emit near infrared rays (hereinafter, referred to as “near infrared rays”).
(Referred to as “light”) toward the incident surface 8 f of the light guide member 8. As shown in FIG. 6, the light emitted from the light projecting element 11 enters the light guide member 8 from the incident surface 8f, and is repeatedly reflected between the front surface 8a and the back surface 8b to travel through the light guide member 8.
The amount of light emitted from the emission surface 8g and incident on the light receiving element 12 is detected by the received light amount detection circuit 14.

Since the front surface 8a of the curved portion 8c is formed with a small uneven surface, a part of the light incident on the front surface 8a as shown by an arrow L1 as shown in FIG. The light passes through and the rest is reflected as indicated by arrow L2. For this reason, each time the light is reflected by the front surface 8a, the amount of light traveling inside the curved portion 8c decreases, and the amount of light incident on the light receiving element 12 in FIG. 6 becomes smaller than the amount of light incident on the incident surface 8f. When no obstruction is applied to the front surface 8a, the light receiving element 1
2 is almost constant, and the received light amount detection circuit 1
4 has an almost constant normal level V0.

Next, a description will be given of the operation in the case where a transparent, white or black paint for shielding far infrared rays is spray-coated by an intruder so as to cover the lens portion 7 of the lens 6 in FIG. Since the lens 6 is generally white, the paint applied for obstruction purposes is usually clear or white.

When the transparent paint is applied to the front surface of the lens 6, the sprayed paint adheres to the front surface 8a because the light guide member 8 is disposed near the lens portion 7.
For this reason, as shown in FIG. 7B, the gap between the small irregularities on the front surface 8a is filled with the coating film 19. Due to the relationship between the refractive index of the coating film 19 and the refractive index of the light guide member 8, the light L1, L2 incident on the front surface 8a
Enters the coating film 19. Thereafter, the light is reflected on the inner surface 19a of the coating film, that is, inside the surface of the coating film 19, and enters the light receiving element 12 in FIG. As a result, the amount of light incident on the light receiving element 12 increases, and the output voltage V of the light receiving amount detection circuit 14 becomes higher than the normal level V0.

On the other hand, when a paint that absorbs light, such as a black paint, is applied to the sensor member cover 6 by spraying,
The lights L1 and L2 incident on the front surface 8a of the light guide member 8 are shown in FIG.
As shown in (c), the light once enters the coating film 19 as in the case of the transparent paint. However, the light L entering the coating film 19
1 and L2 are absorbed by the coating film 19 itself and disappear. As a result, the amount of light incident on the light receiving element 12 in FIG. 6 decreases, and the output voltage V of the received light amount detection circuit 14 becomes lower than the normal level V0.

FIG. 8 (a) is a characteristic diagram showing a change in the output voltage V of the light receiving amount detection circuit 14 before and after the transparent paint spray. The output voltage V increases as the application of the transparent spray proceeds and the coating film 19 becomes thicker. Becomes high and the coating film 19 dries, and the output voltage V in a state where no obstruction is applied is obtained.
It almost doubled to 0. Similar results were obtained when the white paint was sprayed. FIG. 8B is a characteristic diagram showing a change in the output voltage V before and after the black paint spray. The output voltage V decreases as the thickness 19 of the black spray coating 19 increases. The output voltage has dropped to almost half of the output voltage V0.

The detection circuit 15 shown in FIG. 6 has first and second comparators 16 and 17 and an alarm circuit 18.
The output voltage V of the received light amount detection circuit 14 is input to the comparator 16 and the second comparator 17 of the first comparator 16.
Is compared with the first threshold value d1 and the second comparator 17
Is compared with the second threshold value d2. The first threshold value d1 is, for example, a value about 1.5 times the output voltage V0 when no paint is applied, and the second threshold value d2 is a value about 0.75 times the output voltage V0. Is set to

The first comparator 16 compares the input voltage V with the first threshold value d1, and when V> d1, sends a disturbance detection signal to the alarm circuit 18. The alarm circuit 18 An alarm signal is sent to a control room (not shown). On the other hand, the second comparator 17 compares the input voltage V with the second threshold value d2, and when V <d2, sends a disturbance detection signal to the alarm circuit 18, and the alarm circuit 18 Send an alarm signal to the room.

As described above, the security sensor 1 according to the present embodiment has the lens 6 for obstructing the function of the sensor.
When a paint such as transparent, white, or black is spray-applied on the front surface of the light receiving element 12, a change in the amount of incident light on the light receiving element 12 is detected and an alarm signal is sent out, so that an obstacle can be detected.

The light guide member 8 is curved from the light incident surface 8f to the light emitting surface 8g.
The light rays entering the light guide member 8 from the light receiving element 1
, And only the light reflected inside the front surface 8a is incident on the light receiving element 12, so that the amount of light received by the light receiving element 12 when the paint adheres to the unevenness of the front surface 8a is reduced. The change can be increased, and even when a transparent paint, which has conventionally been difficult to detect, is applied, it can be reliably detected. Furthermore, an object such as an insect that temporarily adheres to the lens 6 is not an obstacle, but since the unevenness of the front surface 8a is not filled with the insect, the amount of light received by the light receiving element 12 increases or decreases, and the insect is erroneously regarded as an obstacle. There is no danger of judgment.

FIG. 9 is a partially enlarged longitudinal sectional view of a security sensor according to another embodiment of the present invention. In the drawings, the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts.
This security sensor has a light guide member 8 having a triangular cross-sectional shape disposed between two adjacent Fresnel lens portions 7a formed on a lens 6, and other configurations are as follows.
This is the same as the above embodiment. When the light guide member 8 is disposed in the lens portion 7 as described above, it is difficult to spray paint without the light guide member 8, so that it is possible to reliably detect an obstruction and to suppress an obstructive act. The effect also increases.

FIGS. 10 and 11 show a security sensor according to still another embodiment of the present invention. FIG.
FIG. 11 is a sectional view taken along line XI-XI in FIG. 10. In the drawings, the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts. In the security sensor 1, a circuit board 27 is provided on a base 2 attached to a ceiling surface S, and a board 21 pivotally supported by supporting members 20, 20 mounted on the circuit board 27 so as to be rotatable. The pyroelectric element 4 and the polygon mirror 22 are attached, a plurality of detection areas 23 are formed by the polygon mirror 22, and an opaque synthetic resin hemispherical cover 24 covering the pyroelectric element 4 and the polygon mirror 22. Is attached to the base 2, and a light guide member 8 having a semi-elliptical cross section and an arch shape is attached in the vicinity of a portion where the detection area 23 of the cover 24 passes. The cover 24 merely protects the sensor main body A and does not have a lens function for setting a detection area.

This security sensor includes a second interference detection device 30 as shown in FIG. 10 in addition to the first interference detection device having the light guide member 8, the light projecting element 11, the light receiving element 12, and the like. Have. That is, the circuit board 2 of the base 2
7, a projector 31 that emits near-infrared rays toward the outside of the cover 24 and a light receiver 32 that receives reflected light in the interference detection area 29 set outside the cover 24 are mounted. The active sensor 30 including the light emitter 31 and the light receiver 32 constitutes a second disturbance detection device.
If a large blind cover 33 that covers the entirety of the security sensor and blocks far-infrared rays is installed outside of the cover 24 outside an obstacle that interferes with the operation of the pyroelectric element 4, Near infrared rays cover the blinds 33
The light is reflected by the light receiver 32 and is received by the light receiver 32. Therefore, the presence of the blind cover 33 can be detected by an increase in the output voltage of the light receiver 32.

It should be noted that the light receiver 32 is omitted and the obstruction 3
It is also possible to make the light receiving element 12 receive the reflected light from 3.

According to this embodiment, when the paint is spray-applied on the front surface of the cover 24, the paint is also applied on the front surface 8a of the light guide member 8 and the amount of incident light on the light receiving element 12 is reduced. As in the embodiment, an obstacle can be detected. Further, the second obstruction detection device 30 can also detect an obstruction 33 installed at a position away from the cover.

The light guide member 8 of the present invention can be of various cross-sectional shapes. In addition to the above-described triangular shape (see FIG. 2), a semi-elliptical shape (see FIG. 10), May be partially cut away, and the flat notch may be used as the front surface 8a. In addition, as the obstruction, in addition to the above-mentioned paint, even an adhesive tape such as a transparent cellophane tape, an adhesive or a sealant in the form of a gel or a cream, etc. Since the irregularities on the front surface 8a of the light guide member 8 are buried, according to the present invention,
Can be detected as an obstacle. Further, even if the liquid is water, oil, or the like, the front surface 8
Since the unevenness of a is filled, this can be detected as an obstacle.

[0030]

As described above, according to the present invention,
A light guide member having a front surface formed on an uneven surface forming a part of the outer surface is provided on a lens or a cover of the infrared detection element, and near infrared rays emitted from the light projection element are transmitted to the light guide member. A light-receiving element receives light emitted from the end face and emitted from the other end face, and a detection circuit detects an increase or decrease in the amount of light received by the light-receiving element to detect an obstacle attached to the front surface of the light guide member. With this configuration, it is possible to reliably detect not only white and black paints but also obstacles caused by spray application of transparent paints, which were difficult to detect in the past. Also,
Depending on an object such as an insect that temporarily adheres to the lens or the cover, the uneven surface is not buried, and there is no possibility that the object is erroneously detected as an obstacle.

[Brief description of the drawings]

FIG. 1 is a perspective view of a security sensor with an obstacle detection function according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view taken along line II-II of FIG.

FIG. 3 is a transverse sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a perspective view of the light guide member of the present embodiment.

FIG. 5 is a longitudinal sectional view showing a modification of the light guide member.

FIG. 6 is a schematic diagram illustrating a state of propagation of light in a light guide member and a configuration of an obstacle detection circuit according to the present embodiment.

7A and 7B are diagrams showing a state of light propagation in the light guide member according to the present embodiment. FIG. 7A shows a case where no obstruction is present, FIG. 7B shows a case where a transparent paint is applied as an obstruction, and FIG. ) Shows the case where black paint was applied as an obstacle.

FIG. 8 is a characteristic diagram showing a change in the amount of light incident on the light receiving element before and after a transparent paint and a black paint are applied to the front surface of the light guide member of the present embodiment.

FIG. 9 is a partially enlarged longitudinal sectional view showing another embodiment of the present invention.

FIG. 10 is a sectional view showing still another embodiment of the present invention.

11 is a sectional view taken along line XI-XI in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Security sensor, 2 ... Base, 3 ... Case, 4 ... Pyroelectric element (infrared ray detection element), 6 ... Lens, 7 ... Lens part, 8
... Light guide member, 8a front surface, 8b back surface, 8c curved portion, 8f entrance surface, 8g emission surface, 9 mounting groove, 10 mounting groove
Substrate, 11: light emitting element, 12: light receiving element, 13: driving circuit, 14: light receiving amount detecting circuit, 15: detecting circuit, 16
... first comparator, 17 ... second comparator, 18 ... alarm circuit, 19 ... coating (obstruction), 20 ... support member, 21 ... substrate, 22 ... polyhedral mirror, 23 ... detection area, 24 ... cover, 33 ... blindfold cover (obstruction), A ... body.

Claims (2)

[Claims] 1. A main body having an infrared detecting element, a lens mounted on the main body and setting a detection area of the infrared detecting element or a cover for covering an infrared incident surface side of the infrared detecting element; A front surface forming part of the outer surface,
A light guide member having an incident surface at one end and an exit surface at the other end; a light projecting element for projecting light from the incident surface to the inside of the light guide member; and a light receiving element for receiving the projected light beam through the exit surface. A detection circuit for detecting adhesion of an obstruction to the front surface based on an amount of light received by the light receiving element, and a part of the projected light beam is disposed outside the light guide member on the front surface of the light guide member. A security sensor in which a large number of irregularities are formed to transmit light to the other side and reflect other parts inward. 2. The light-guiding member according to claim 1, wherein the light-guiding member is curved from the incident surface to the exit surface, whereby light rays reflected from the light-emitting element are reflected inside the front surface. A security sensor set so that only reflected light is incident on the light receiving element.