JPH0682392A - Damage detector for transparent body - Google Patents

Abstract

PURPOSE:To detect breaks or cracks in a transparent body such as glass. CONSTITUTION:A light projection part 12 equipped with a light emitting element 20 is provided on one end side of a transparent body 11 and the light emitting element 20 projects sensor light R into the transparent body 11. A light detection part 13 equipped with a photodetector 30 is provided on the other end side of the transparent body 11 and an electric circuit part 14 is connected to the light detection part 13. The electric circuit part 14 judges that the transparent body 11 is broken when the quantity of the sensor light R detected by the photodetector 30 reaches a predetermined value or less. The light projection part 12 is provided so as to allow the sensor light R to be incident on the transparent body 11 at an incident angle theta' equal to or more than a critical angle theta represented by sintheta=n2/n1 when the refractive index of the transparent body 11 is set to n1 and the refractive index of a liquid is set to n2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting breakage of transparent bodies such as glass panels and synthetic resin panels used for windows and doors of buildings and vehicles, showcases and the like.

[0002]

2. Description of the Related Art Various sensors are used in a structure using a transparent body such as a window glass for crime prevention reasons. For example, there is known a system in which an infrared sensor or an optical sensor is installed in the vicinity of a window glass or the like in order to detect that a window glass or a show window is destroyed by a suspicious person, and notifies when an object crosses the sensor light. ing. In addition, opening / closing of the door or window is also detected by attaching a reed switch to the door or window.

[0003]

However, the former case is not applicable to places where a large number of unspecified persons may approach the sensor or cross the sensor light, such as a showcase in an exhibition. Not only is it difficult, but insects, dogs, cats, etc. react even if they block the sensor light,
The original crime prevention function may not be exhibited.

In the latter system, which detects the opening and closing of a door or a window by a reed switch, there is a problem that a person who breaks the glass and intrudes cannot be detected. Therefore, an object of the present invention is to provide a breakage detecting device for a transparent body that can detect breakage such as cracking or cracking of a transparent body such as glass.

[0005]

The device of the present invention developed to achieve the above object is a light emitting device which is provided at one end of a transparent body made of a light transmissive material and projects sensor light into the inside of the transparent body. A light projecting unit including an element, a light receiving unit provided on the other end side of the transparent body for receiving the sensor light, and an amount of the sensor light received by the light receiving device is equal to or less than a predetermined value. comprising an electrical circuit section that determines whether or not, the light projecting unit, n ₁ the refractive index of the transparent body, when the refractive index of the liquid adhering to the transparent body and the n _2, sin θ = n ₂ /
The sensor light is incident on the transparent body at an incident angle equal to or greater than the critical angle θ represented by n ₁ . The transparent body is made of glass or synthetic resin and may be colorless and transparent or may be colored, that is, it may be made of a light transmissive material.

[0006]

The sensor light projected from the light emitting element to the inside of the transparent body at the above-mentioned incident angle goes to the light receiving section by repeating total reflection inside the transparent body unless the transparent body is damaged, and is detected by the light receiving element. To be done. Even if a liquid such as water adheres to the surface of the transparent body, the sensor light incident on the transparent body at the above incident angle is totally reflected at the contact interface between the transparent body and the liquid without leaking to the outside. The sensor light reaches the light receiving element.

When the transparent body is cracked or cracked, the sensor light leaks to the outside at the damaged portion of the transparent body and is reflected in an unspecified direction, so that the amount of light reaching the light receiving element is reduced. The decrease in the amount of light is detected by the electric circuit unit, and when the amount of decrease in the amount of light below a predetermined value is detected, it is determined that the transparent body has been damaged, and appropriate measures such as issuing an alarm are taken.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The transparent body breakage detection device 10 shown in FIG. 1 includes a light projecting portion 12 provided on one end side of a glass plate as an example of the transparent body 11 and a light receiving portion provided on the other end side of the transparent body 11. 13 and an electric circuit section 14 and the like. A plurality of pairs of the light projecting unit 12 and the light receiving unit 13 may be provided.

The light projecting section 12 comprises a light emitting element 20 such as a light emitting diode, and a mounting base 21 for optically connecting the light emitting element 20 to the transparent body 11. Mounting base 2
1 is made of a transparent material having a refractive index similar to that of the transparent body 11 (a material having a refractive index similar to that of glass in this embodiment), and is bonded to the transparent body 11 by a transparent adhesive 22. The adhesive 22 also has the same refractive index as the transparent body 11.

The light emitting element 20 projects the sensor light R into the inside of the transparent body 11. When the refractive index of the transparent body 11 is n ₁ and the refractive index of water is n ₂ , sin θ = n ₂ / n ₁
The mounting angle of the light emitting element 20 with respect to the transparent body 11 is set so that the sensor light R is incident on the transparent body 11 at an incident angle θ ′ that is greater than or equal to the critical angle θ.

For example, if the refractive index n _{1 of} glass is 1.5 and the refractive index n _{2 of} water is 1.33, the critical angle θ at the contact interface between glass and water is such that sin θ = 1.33 / 1.5 = 0.8867. Therefore, θ in this case is 62.5 °. Therefore, in this example, the mounting angle of the light emitting element 20 is set so that the sensor light R is incident on the transparent body 11 at an incident angle θ ′ of about 63 ° or more. When the sensor light emission angle of the light emitting element 20 is too wide, a lens is provided between the light emitting element 20 and the mounting base 21 so that the converged sensor light R is emitted to the transparent body 11. Good.

The light receiving section 13 is provided with a light receiving element 30 using a photodiode or the like for receiving the sensor light R, and a mounting base 31 for optically connecting the light receiving element 30 to the transparent body 11. The mounting base 31 is made of a transparent material having a refractive index similar to that of the transparent body 11 (a material having a refractive index similar to that of glass in this embodiment), and is bonded to the transparent body 11 by a transparent adhesive material 32. The adhesive 32 also has the same refractive index as the transparent body 11.

The electric circuit section 14 is a controller using a microcomputer or the like, and when the light quantity of the sensor light R received by the light receiving element 30 is below a predetermined value, it is judged that the transparent body 11 is damaged, Electrical control is performed such that an appropriate crime prevention device such as an alarm device is activated, or a signal is sent to notify the guard room.

In the apparatus 10 of the embodiment having the above-mentioned structure, the sensor light R projected from the light emitting element 20 into the inside of the transparent body 11 at the incident angle θ'is repeatedly received in the inside of the transparent body 11 by repeating total reflection. 13 toward the light receiving element 3
Detected by 0.

As shown in FIG. 3, when the transparent body 11 is cracked or the transparent body 11 is broken, the damaged portion 11a is broken.
Since the sensor light R leaks from or is reflected in an unspecified direction,
The amount of light received by the light receiving element 30 is significantly reduced. When the decrease in the amount of light exceeds a predetermined value, it is determined that the transparent body 11 has been damaged, an appropriate device such as an alarm device is activated, or a notification is sent to the guard room.

When there is a possibility that external illumination light or sunlight enters from the damaged portion of the transparent body 11, the light-receiving element 30 detects the frequency-modulated sensor light to detect the illumination light or the sun. You may make it prevent the erroneous determination by the influence of the light increase by light.

In the apparatus 10 of this embodiment, the sensor light R is incident at an incident angle θ ′ that is equal to or greater than the critical angle θ, so that water 35 adheres to the transparent body 11 due to rain or dew, or the transparent body 1
Even if water is spilled on top of 1, the water 35 and the transparent body 11
The sensor light R can be totally reflected at the contact interface with (glass in this embodiment). Therefore, light does not leak from the place where the water 35 adheres. In addition, transparent body 1
Insects stop on the surface of 1 and people, dogs, cats, etc. are transparent 1
There is no risk of malfunction even when touching 1, and the transparent body 11
The alarm action can be executed only when the is damaged.

As shown in FIG. 4, the locking device 4
If the light emitting portion 12 or the light receiving portion 13 is provided near 0,
Since it is possible to immediately detect that the transparent body 11 has been broken around the locking device 40, it is effective in preventing suspicious activity such as opening the locking device 40 by inserting a hand from a cracked portion.

Further, like the damage detecting device 50 shown in FIG. 5, a light projecting portion 51 for projecting the sensor light R having a spread.
And a light receiving section 52 is provided on the diagonal line of the transparent body 11.
May be disposed, and the light guide member 60 may be provided on the edge portions 53 and 54 of the transparent body 11 located on the light receiving portion 52 side. The light guide member 60 has a function of guiding the sensor light R reaching the edge portions 53 and 54 to the light receiving element 30. In this case, if a plurality of reflecting portions 61 such as half mirrors are provided at appropriate positions of the light guide member 60 and the sensor light R is reflected toward the light receiving element 30, the breakage of the transparent body 11 can be detected over a wide range. can do.

[0020]

According to the present invention, it is possible to notify that the transparent body has been damaged, and there is an excellent effect in crime prevention or safety.

[Brief description of drawings]

FIG. 1 is a side view of a part of a damage detection device showing an embodiment of the present invention.

FIG. 2 is a perspective view of a transparent body including the damage detection device shown in FIG.

FIG. 3 is a side view showing a state where the transparent body is broken in the breakage detection device shown in FIG.

FIG. 4 is a perspective view showing an embodiment in which a damage detection device is provided near the locking device.

FIG. 5 is a plan view of a transparent body provided with a damage detection device showing another embodiment of the present invention.

[Explanation of symbols]

10 ... Damage detection device, 11 ... Transparent body, 12 ... Projector, 1
3 ... Light receiving part, 14 ... Electric circuit part, 20 ... Light emitting element, 30
…Light receiving element.

Claims (1)

[Claims] 1. A light projecting portion provided on one end side of a transparent body made of a light-transmissive material and provided with a light emitting element for projecting sensor light into the inside of the transparent body, and on the other end side of the transparent body. And a light receiving element having a light receiving element for receiving the sensor light, and an electric circuit section for determining whether or not the amount of the sensor light received by the light receiving element is less than or equal to a predetermined value. light unit, when n ₁ the refractive index of the transparent body, the refractive index of the liquid adhering to the transparent body and the _{n 2, sin θ = n 2} / n 1
An apparatus for detecting damage to a transparent body, wherein sensor light is incident on the transparent body at an incident angle equal to or greater than the critical angle θ represented by.