JPH0535363Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an infrared reflecting mirror, and particularly to an infrared reflecting mirror for an infrared sensor for security purposes.

[Background of the idea]

In recent years, crime prevention sensors have been used such as sensors that utilize the Doppler effect of microwaves, sensors that utilize the transmission and reception of infrared rays, and passive sensors that utilize the pyroelectric effect or thermoelectromotive force. Among these, sensors that utilize infrared light transmission and reception are the most widely used because they are highly reliable and the cost of the elements is low.

Examples of these conventional infrared sensors will be explained with reference to FIGS. 3 and 4. First, in the example shown in Fig. 3, the emitter 2 and the receiver 3 are installed across the space to be detected, and a moving object such as a person passing through this space blocks the infrared light from the emitter 2, causing the infrared light to be detected by the receiver. 3, it is detected that there is an intrusion. In this case, to increase the confidentiality of the device,
It is necessary to drill and bury holes in the walls on both sides, which is not desirable from an aesthetic point of view. Furthermore, the optical axes of the emitter 2 and the light receiver 3 must be aligned across the space to be detected. In addition, since the emitter 2 and the receiver 3 are installed on the back side of the wall across the aisle, the wiring has to be routed for a long time under the ceiling, which reduces the time and labor involved in drilling holes and aligning the optical axis. It also had many drawbacks.

In order to overcome these shortcomings, a system as shown in FIG. 4 was proposed in which the light emitter and receiver were integrated. In this example, the receiver 3 detects infrared rays emitted from the projector 2 reflected by a moving object such as a person and returned. In this case, the reflected light is extremely weak, so it must be amplified by pulse-driving the infrared light emitting element, applying alternating current modulation, and passing through a special amplification circuit, compared to the cut-off type shown in Figure 3. However, there was a drawback that the S/N ratio could not be made sufficiently large. In addition, the reflectance of the moving object to be detected is not constant, and the device does not work, especially if the person is wearing clothing that does not reflect infrared rays.

[Purpose of invention]

An object of the present invention is to provide an infrared reflector for realizing an infrared sensor that can provide a sufficient S/N ratio like a blocking type sensor while integrating a light emitter and a receiver.

[Summary of the idea] In order to integrate the emitter and receiver and ensure a sufficient amount of infrared light entering the receiver as in the blocking type, as shown in Figure 2, the emitter and receiver are installed on the wall, etc. The infrared reflector 1 may be installed on the opposing surfaces.
However, if this infrared reflecting mirror also reflects visible light, the confidentiality of the device would be lost, so it must be made opaque to visible light.

The present invention provides an infrared reflector configured by adding a thin film that reflects infrared light to the back surface of a material that is opaque to visible light and transparent to infrared light. The material that is opaque to light and transparent to infrared rays is a synthetic resin containing organic dye, and has extremely high concealment properties that make it unrecognizable to the human eye as a reflective mirror. It is equipped with an infrared reflecting mirror characterized by the following.

[Example of idea]

As shown in FIG. 1, the infrared reflector 1 of the present invention has a metal thin film 1B etc. deposited on the back surface of a material 1A that is opaque to visible light but allows infrared light to pass through. It was formed by such methods.

Specifically, it is implemented as follows. When red and green organic dyes are simultaneously added to a two-component epoxy resin, it is easy to reduce the visible light reflectance to 1% or less at a thickness of 1 mm. In general, many organic dyes have a transmittance of about 80% for infrared light, so for example, the emission wavelength of an infrared light emitting diode made by doping silicon
It can show sufficient transmittance for 940 nanometers.

In this way, a reflective film 1B such as a thin metal film is formed on the back surface of the synthetic resin plate 1A, which is opaque to visible light and highly transparent to infrared light, by vapor deposition or the like.
When used as an infrared reflector, it will not be noticed as a reflector in the visible range.

This reflective mirror 1 with high secrecy is connected to the light emitters and receivers 2 and 3.
on the wall facing the intrusion warning device integrated with the
When installed as shown in FIG. 2, moving objects such as humans block infrared light, making it possible to detect a high S/N ratio similar to the conventional blocking type.

In order to further enhance secrecy, it is of course possible to decorate the outer shape of the infrared reflector itself, or to camouflage it by drawing a picture on the surface, as long as the advantages of the present invention are not impaired. be.

[Effect of idea]

By using the infrared reflector obtained by this invention, the emitter and receiver can be integrated, reducing work time and labor including drilling and optical axis alignment, while achieving a sufficient S/N ratio like a blocking type. It is possible to realize an infrared sensor that can detect visible light, and it is highly concealable because it cannot be noticed that it is a reflective mirror for visible light.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of an infrared reflector according to the present invention, Fig. 2 is a schematic diagram showing an example of an infrared sensor using the reflector shown in Fig. 1, and Fig. 3 is a schematic diagram showing an example of an infrared sensor using the reflector shown in Fig. 1. A schematic diagram showing an example. FIG. 4 is a schematic diagram showing an example of a conventional infrared sensor in which a light emitter and receiver are integrated. 1... Infrared reflecting mirror, 1A... Visible light opaque infrared light transmissive plate, 1B... Infrared light reflecting film, 2...
... Emitter, 3... Light receiver, 4... Wall, 5... Moving object such as a person.

Claims (1)

[Scope of utility model registration request] In an infrared reflector configured by adding a thin film that reflects infrared light to the back side of a material that is opaque to visible light and transparent to infrared light,
An infrared reflecting mirror characterized in that the material opaque to visible light and transparent to infrared rays is a synthetic resin containing an organic dye.