JP2000111656A - Detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a detecting device difficult to understand whether or not it is a detecting device taking a measure against mischief from an external appearance, miniaturize the device, and facilitate design in the detecting device for detecting infrared rays radiated from the human body. SOLUTION: A sensor for detecting transmitted infrared rays is provided inside a transmitting window 2 for passing infrared rays radiated from the human body, and for example, a light conductor 3 is arranged in a state of having the continuous outside surface on the outside surface of the transmitting window 2. Near infrared rays propagating inside a thickness of this light conductor are emitted by a light emitting element, and the propagated near infrared rays are received by a light receiving element. When paint by a spray is applied to the transmitting window 2 by mischief, since the outside surface of the light conductor is also applied, a quantity of light radiated outside by passing through the outside of the light conductor reduces, so that a light receiving quantity of the light receiving element changes to thereby detect abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device for detecting infrared rays radiated from a human body, and to a device provided with a countermeasure against mischief.

[0002]

2. Description of the Related Art As a human body detector for detecting an intruder,
Passive Infra-red Sensor (PIR), which uses a pyro-electric element to detect infrared radiation emitted from the intruder's body, is widely used due to its low cost. . However, since this type of sensor detects only the amount of change in infrared light, no alarm is output if there is no change in infrared light.

That is, in a time period other than the guard time period, for example, in the daytime, a detection window, that is, a transmission window that transmits infrared rays, is coated with a paint by a spray that blocks infrared rays, or a cover that covers the detection window is covered. If a mischief is placed in which an obstacle is placed, the amount of infrared rays received by the pyroelectric element in the detection window does not change even during a guard time, for example, at night, so that no alarm is output. . In particular, a transparent spray or a cover having the same shape as the sensor is a major problem that is difficult to be found even by visual inspection by patrol guards.

As a countermeasure against such mischief, there is a sensor using a combination of sensors based on different principles, for example, a microwave and a passive infrared sensor, an ultrasonic and a passive infrared sensor, or the like. Thus, even if the infrared rays are blocked by a spray or the like, microwaves and ultrasonic waves are not blocked, so that an alarm can be output.

Another measure is to combine a passive infrared sensor with another type of infrared sensor.
That is, it is a reflection type or transmission type infrared sensor. Passive infrared sensors only unilaterally receive infrared light from the human body, and are therefore called passive or passive, whereas these infrared sensors emit light as well as light receiving elements that receive infrared light. It also has a light emitting element and is therefore called active or active.

[0006] The former uses a plurality of sensors of different principles, and thus requires sensors other than infrared sensors, so that the cost is generally high. The latter example is
There are multiple types.

That is, first, a light-emitting element and a light-receiving element which constitute an active infrared sensor are provided outside a detection window to detect an obstacle or the like (US Pat.
094, Japanese Patent No. 2521505). The second is a method of providing a light emitting element and a light receiving element constituting an active infrared sensor outside the detection window and observing the state of the detection window (US Pat. No. 5,499,016). Third, a method of providing a light-emitting element constituting an active infrared sensor outside the detection window, providing a light-receiving element inside, and observing obstacles and the state of the detection window (US Pat. No. 5,489,892;
74622, Japanese Utility Model Application Laid-Open No. 62-187397). Fourth, an active infrared sensor is provided outside the detection window, and the above-described methods are combined with several types (USP5243).
326). Fifth, a method of forming a plurality of beams in the front part outside the detection window (EP0817148). Sixth, there is a method in which a light emitting element and a light receiving element constituting an active infrared sensor are provided inside a detection window, and it is observed whether or not the detection window has been tampered with (JP-A-2-287278).

[0008]

However, in the first to fifth aspects of the prior art, the element is provided outside the detection window, so that it is easy to see from the appearance that the countermeasures are taken. Has become. Then, an intruder or the like can easily determine whether or not the detection device has taken the countermeasure against tampering.

Sixth, on the other hand, the active type infrared sensor is provided inside the detection window, and it is difficult to understand countermeasures against mischief. However, in order to prevent the infrared rays exchanged between the light emitting element and the light receiving element provided inside the detection window from interfering with the components and the housing inside the detection window, a large space is secured inside the detection window. There must be.
In other words, a large space for propagation of infrared rays is required, so that the size of the apparatus is increased or the design is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and it is difficult to determine from the appearance whether or not a detection device has a tamper-resistant measure, and the size of the device can be reduced to facilitate design. It is an object to provide a detection device.

[0011]

Means for Solving the Problems To solve the above problems, a first invention is to provide a transmission window for transmitting infrared rays emitted from a human body, a sensor for detecting the infrared rays transmitted through the transmission window, A light guide that is provided as a part of the transmission window, has a continuous outer surface on the outer surface of the transmission window, or is provided in a state close to the transmission window, and emits light propagating inside the thick portion of the light guide. A light-receiving element that receives the propagated light; and a detecting unit that detects an abnormality based on a change in the amount of light received by the light-receiving element.

A second aspect of the present invention is a detection device characterized by further forming irregularities on the outer surface of the light guide.

A third aspect of the present invention is a detecting device, further comprising cutting a light guide across a light propagation path, and forming a gap portion through which light propagates in the air between opposing cut surfaces. .

According to a fourth aspect of the present invention, there is provided a detecting device, wherein the light guide has an arc shape following the outer surface of the transmission window.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Structure of Embodiment) FIGS. 1 to 3 show the structure of an embodiment of the present invention. In FIG.
The appearance of the detection device 1 has a detection window 2 as a transmission window through which infrared rays radiated from a human body are transmitted. Inside the detection window 2, a sensor (not shown) for detecting transmitted far infrared rays is arranged. ing. The outer surface of the detection window 2 has an arc shape so as to form a part of a cylinder. Below the detection window 2, an arc-shaped band-shaped light guide 3 continuous with the detection window 2 is provided. The outer surfaces of the detection window 2 and the light guide 3 are continuous and have the same curved surface, so that the boundaries are difficult to see from the outside. The material of the light guide 3 may be any material as long as it transmits near-infrared rays, which will be described later, used for detecting an abnormality such as mischief. And the detection window 2,
A sensor (not shown), the light guide 3 and the like are housed in the case 4 and attached to the wall 5.

The detection window 2 as a transmission window is made of a material such as polyethylene which blocks visible light and transmits far infrared rays well. In some cases, a Fresnel lens for condensing light is provided inside the detection window 2, and when a plurality of detection areas are required, a plurality of Fresnel lenses are provided. Further, in the main detection window 2, there are provided a pyroelectric element constituting a sensor for detecting far-infrared rays emitted from a human body, a control circuit for amplifying and judging the signal and outputting an alarm.

As shown in FIG. 2, a light emitting element 6 for emitting near-infrared rays is provided at one end of the arcuate strip-shaped light guide 3.
Near-infrared light propagates through the thick portion of the light guide 3. At the other end of the light guide 3, a light receiving element 7 for receiving the transmitted near infrared rays is provided. The light guide 3 is attached to a case 4, and the light emitting element 6 and the light receiving element 7 are attached to a substrate 8 in the case 4.

FIG. 3 is a block diagram of a detection circuit for detecting an abnormality by the light emitting element 6, the light receiving element 7, and the light guide 3. That is, the light emitting element 6 is a near infrared LED
Then, in order not to be affected by disturbance light, pulse lighting driving is performed. The light projecting circuit 9 is a circuit for driving the near-infrared LED with a constant current. The oscillation circuit 10 is a near infrared ray LE
This is a circuit for generating a signal for lighting D in pulses.
The external light compensating circuit 11 responds to a pulse signal of the near infrared LED among the electric signals generated by receiving the light receiving element 7, and a disturbance that blinks with other direct current light from sunlight or a lighting lamp or a commercial power frequency. This is a circuit that does not respond to light. This external light compensating circuit 11 comprises an integrating circuit. BPF
The amplifier circuit 12 is a band-pass amplifier circuit that amplifies only a signal component of a required frequency. The detection circuit 13 is a circuit for converting a signal that changes in AC into DC. The smoothing circuit 14 is a circuit for smoothing a pulse-changing signal. The comparator circuit 15 is a circuit for comparing a signal level with a trigger level and outputting a detection signal. The alarm circuit 16 is a circuit for notifying a detection signal to the outside, and has an indicator light, a relay for activating another device, and the like.

(Operation of Embodiment) The operation of detection by the detection window 2 of the detection device 1 will be described below. Detection device 1
At the time of caution, far infrared rays emitted by an object such as a human body in the detection area 17 are condensed by a Fresnel lens provided in the detection window 2 and guided to the pyroelectric element. If there is no moving object in the detection area, there is no change in the intensity of far-infrared rays, and the output signal of the pyroelectric element does not change. The temperature at this time is called a background temperature. When an object having a temperature difference from the background temperature, such as a human body, enters the detection area 17, the output signal of the pyroelectric element changes. By amplifying the change in the output and comparing it with a threshold, it is determined that the human body is present, and an alarm is output.

Next, the operation of detecting an abnormality such as mischief by the light guide 3 will be described. As shown in FIG. 2, the near-infrared ray emitted from the light emitting element 6 is guided to the inside of the thickness of the arcuate light guide 3, and partly repeats total reflection at the boundary between the light guide 3 and air. Propagation, light receiving element 7
To reach. Other near-infrared rays pass through the interface between the light guide 3 and the air and are emitted to the outside.

Here, if a foreign substance such as a paint adheres to the light guide 3 by spraying or the like, the near-infrared ray transmitted through the light guide 3 is reflected by the foreign substance and is not radiated to the outside, and reaches the light receiving element 7. The amount of received light increases, and an abnormality can be detected by detecting a change in the amount of received light. In addition, by adjusting the output of the light emitting element 6 or the sensitivity of the light receiving element 7, it is possible to detect even a foreign substance that does not adhere to the surface of the light guide 3 (for example, an object that covers the entire detector).

(Effects of Embodiment) As described above,
In this embodiment, the light-emitting element 6 and the light-receiving element 7 do not need to be provided outside the detection window 2 which is a transmission window, and it is difficult to determine from the appearance whether or not the detection device has a countermeasure against mischief. Further, the near-infrared ray exchanged between the light emitting element 6 and the light receiving element 7 propagates inside the thick part of the light guide 3,
There is no need to secure a wide space for propagation inside the detection window, which is a transmission window, as in the related art, so that the device can be downsized and the design can be facilitated.

Further, by forming the light guide 3 in an arc shape, the amount of light radiated to the outside is increased as compared with the case where the light guide 3 is formed in a linear shape. Since the difference from when the amount is small increases, the change in the amount of light received by the light receiving element 7 can be increased, and detection of an abnormality becomes easier. In addition, since the light guide 3 and the detection window 2 have the same outer surface continuous and have the same curved surface, and the boundary is difficult to see from the outside, the light guide 3 and the detection window 2 are mischief only by the detection window 2. It is difficult to do so, and an excellent human body detection that reliably detects mischief on the detection window 2 becomes possible. Further, in the above embodiment, the light used for detecting a human body is far infrared, and the light for detecting anomalies such as mischief is near infrared, so that both rays are prevented from affecting each other's detection and detection. it can.

(Other Embodiments) In the above embodiment, no special processing was applied to the surface of the light guide 3. However, in other embodiments, the processing for making the surface of the light guide 3 uneven is 19. It can also be applied (FIG. 4). In this case, light such as near-infrared light is likely to be irregularly reflected by the unevenness 19 on the surface of the light guide 3, and therefore, the amount of light radiated outside increases. If the irregularities 19 are filled with mischievous foreign substances, the amount of light such as near-infrared rays emitted to the outside is reduced. Therefore, the change in the amount of light received by the light receiving element can be increased,
Abnormal detection becomes easier.

Generally, when the surface of the light guide 3 is mirror-finished, the reflection efficiency becomes the best. In another embodiment,
By making the surface of the light guide roughened, fine irregularities can be formed (not shown). In this case, the rough surface of the light guide 3 is filled with fine dirt such as paint by spraying, and the amount of received light increases. By detecting this, mischief can be detected.

Further, in the above embodiment, the light guide 3 is not cut off. In other embodiments, for example, as shown in FIG. 5, the light guide 3 is cut across the light propagation path. Then, a gap portion 23 through which light propagates in the air 22 between the opposed cut surfaces 20 and 21 can be formed. In this case, for example, when paint is applied to the cut surfaces 20 and 21 with a colored spray or the like, the amount of light received by the light receiving element is greatly reduced, so that the abnormality can be easily detected.

In the above embodiment, the light guide 3 is
Although the outer surface is continuous with the detection window 2 and the boundary is hard to see from the outside, in other embodiments, the detection window 2 can also serve as a display window such as an operation indicator light that can be distinguished from the outside. At this time, the operation indicator selects a wavelength that does not cause near-infrared noise. Alternatively, the light guide 3 can be provided in a state where the light guide 3 is a part of the detection window 2. In other words, if the infrared light used to detect the human body and the light used to detect anomalies such as mischief are distant in nature, and the two are unlikely to affect each other, the former infrared light will pass through the detection window. However, the latter light is made possible by propagating through the thick portion of the detection window as a light guide.

Furthermore, it is possible to provide the light guide in a state close to the transmission window. That is, it is possible to avoid the light guide 3 and make it difficult to mischief only the detection window 2 by being sufficiently close to each other even if they are slightly separated and not continuous. In the above embodiment, the light guide 3
Is an arc shape, but in another embodiment, as shown in FIG. 6, the shape of the light guide may be a linear shape. At this time, the light guide 3 may be provided on only one side of the rectangular detection window 2, for example, but in order to further detect mischief, it is provided on the four sides of the detection window 2 as shown in FIG. Is also good. Alternatively, it may be provided only on two opposing sides.

In the above embodiment, the detection device 1 is mounted on the wall 5, but in other embodiments, the detection device 1 may be mounted on the ceiling 24. That is, the detection device 1 has a hemispherical detection window 2 provided on a base 25 attached to a ceiling, and the detection window 2 is partially provided with an arcuate light guide 3. . In the above embodiments, near-infrared light is used as light for detecting anomalies such as mischief, but in other embodiments, light of other wavelengths can be used.

[0030]

As described above, according to the first, second, third or fourth aspect of the present invention, light from the light emitting element propagates inside the thick part of the light guide and is received by the light receiving element. . If paint is applied to the transmission window by spraying due to mischief, the outer surface of the light guide is also applied, so the amount of light radiated outside through the outer surface of the light guide increases and decreases, and the amount of light received by the light receiving element changes I do. Therefore, an abnormality is detected.

The light-emitting element and the light-receiving element do not need to be provided outside the transmission window, and it is difficult to determine from the external appearance whether or not the detection device has a countermeasure against mischief. In addition, light exchanged between the light-emitting element and the light-receiving element propagates inside the thick part of the light guide, so that it is not necessary to secure a large space inside the transmission window, so that the device can be downsized and designed. Becomes easier.

According to the second aspect of the present invention, irregular reflection of light is more likely to occur due to the unevenness, so that the amount of light emitted to the outside is increased, and the unevenness is buried by paint or the like and emitted to the outside. Since the difference from the case where the amount of incident light is small increases, the change in the amount of light received by the light receiving element can be increased, and the abnormality can be easily detected.

Further, according to the third aspect of the present invention, when paint is applied to the cut surface, the amount of light received by the light receiving element is greatly reduced, so that the abnormality can be easily detected.

According to the fourth aspect of the present invention, the amount of light radiated to the outside is increased as compared with the case where the light guide is formed in a straight line by making the light guide into an arc shape, and the outer surface is made of paint or the like. Since the difference from when the amount of light applied and radiated to the outside is small increases, the change in the amount of light received by the light receiving element can be increased, and abnormality detection becomes easier.

[Brief description of the drawings]

1A and 1B show a detection device according to an embodiment of the present invention, wherein FIG. 1A is an external front view, and FIG. 1B is a side view of FIG.

FIG. 2 is a plan view showing the light guide of FIG.

FIG. 3 is a block diagram showing a circuit for detecting an abnormality such as mischief by the light guide of FIG. 1;

FIG. 4 is a view showing a light guide of another embodiment and corresponding to FIG. 2;

FIG. 5 shows a light guide of still another embodiment, and FIG.
FIG.

FIG. 6 is a diagram showing a light guide of still another embodiment.

FIG. 7 is a front view of a detection device provided with the light guide of FIG. 6;

FIG. 8 shows a detection device according to still another embodiment, wherein (A) is a front view and (B) is a bottom view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detecting device 2 Detecting window 3 Light conductor 4 Case 4 5 Wall 6 Light emitting element 7 Light receiving element 8 Substrate 17 Detection area 19 Unevenness 20, 21 Cut surface 22 Air 23 Gap 24 Ceiling 25 Base

Claims (4)

[Claims] 1. A transmission window that transmits infrared rays emitted from a human body, a sensor that detects infrared rays transmitted through the transmission window, and a part of the transmission window, which is continuous with an outer surface of the transmission window. A light guide provided in a state having an outer surface or in a state close to the transmission window, a light emitting element that emits light propagating inside the thick part of the light guide, and a light receiving element that receives the propagated light Detecting means for detecting an abnormality based on a change in the amount of light received by the light receiving element. 2. The detecting device according to claim 1, wherein irregularities are formed on an outer surface of the light guide. 3. The detection device according to claim 1, wherein the light guide is cut across a light propagation path, and a gap portion for transmitting light in the air between the opposing cut surfaces is formed. 4. The detecting device according to claim 1, wherein the light guide is formed in an arc shape along an outer surface shape of the transmission window.