JPH05303961A - Halogen type near infrared lighting system - Google Patents

Abstract

PURPOSE:To minimize the temperature rise in each part. CONSTITUTION:The emitted light from a halogen lamp 1 is incident upon a parabolic mirror (semi-reflecting mirror) 2A having the characteristic of reflecting only the near infrared area situated with a focus placed on the halogen lamp 1, and the reflected light from the semi-reflecting mirror 2A is passed through a visual light cut filter 3 for removing a visual light component, and emitted to a on object to be lighted. Thus, the temperature rise in each part such as the visual light cut filter is minimized. Consequently, using a high- luminance and large-capacity halogen lamp as a light source, a high-luminance halogen type near infrared lighting device can be realized. The tolerance of each part is raised for the same capacity of the halogen lamp, and the life is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device used for obtaining a good image signal at the time of image pickup by a TV camera,
In particular, the present invention relates to an illuminating device that uses a halogen lamp as a light emitting source and mainly uses only near-infrared components in irradiation light as illumination light for imaging.

[0002]

2. Description of the Related Art TV cameras are widely used in industrial and consumer applications, and when a light amount from a subject is insufficient at the time of image pickup such as at night, an illumination device is used to supplement the light amount and raise the illuminance. Although a technology for high-speed shutters has been established for TV cameras with CCD imaging units, it is necessary when capturing a moving vehicle for traffic, and the imaging time (exposure time) is shortened when using this high-speed shutter. For this reason, the amount of light tends to be insufficient, and even in such a case, a lighting device is generally required.

In particular, near-infrared imaging is used when the irradiation of visible light is dazzling to humans and is not preferable (for traffic), when it is not desired to let the person know the facts of shooting, or when it is desired to obtain a good image regardless of the weather. The demand is increasing. When mainly imaging the near-infrared light from the object to be photographed, several types of illuminating devices that emit near-infrared light are used,
A halogen lamp is used as a light source and a visible light cut filter is inserted in the optical path (a halogen type near infrared lighting device) is often used.

For example, in a traffic image processing apparatus, as shown in FIG. 3, a road is photographed using a TV camera 9 installed about 6 m above the road, and the traffic image processing apparatus 10 takes a picture of the image of the traveling vehicle. A device that detects 11 and recognizes the registration number of the license plate requires the lighting device 30 to handle night time. In the figure, two lighting devices 30 are shown. Information such as vehicle detection and recognized vehicle number is transmitted to a central processing unit and used, for example, for travel time calculation. Further, for convenience of passersby, information such as estimated travel time is transmitted from the center to the display 12 at the observation point and displayed. The imaging time (shutter time) is 1 /
A high speed shutter of about 1000 s is used. Figure 4
Two lighting devices 30 and T using a halogen lamp as a light source
It shows a state in which the V camera 9 is attached to a support portion 13 that is appropriately installed above the road.

By the way, in the halogen type near-infrared lighting device 30 using the above halogen lamp, the light emitted from the halogen lamp also contains a visible light component, and when it is used as it is for traffic use, it dazzles the vehicle driver. Since it is dangerous because it is given, a visible light cut filter is arranged on the front surface to cut visible light and project only an infrared component as illumination light. In addition, a protective glass is often provided on the front surface for protection.

FIG. 5 shows a sectional view (a) and a front view (b) of a conventional halogen type near infrared lighting device 30. In the housing 5, the halogen lamp 1 is located near the focal point of the parabolic surface by the parabolic mirror 8 which also serves as a supporting portion.
It is supported with. A visible light cut filter 3 for removing visible light components is attached to the front (irradiation side) of the halogen lamp 1 and the parabolic mirror 8. A protective glass 4 is provided on the outer side of the visible light cut filter 3 for protection. Reference numeral 6 is a lead wire for supplying a current to the halogen lamp 1. The light from the halogen lamp 1 is directly or reflected by the surface of the parabolic mirror 8 and mostly enters the visible light cut filter 3 and is transmitted and the visible light component is removed. 4 becomes a beam-like irradiation light through the object 4 (here, the vehicle 11
In particular, illuminate the license plate part).

The table of FIG. 6 shows an example of the spectral power characteristic (L) of the light generated by the halogen lamp 1 and the spectral characteristic (F) of the visible light cut filter 3 together with the human visual sensitivity characteristic (M). It is a thing. It can be read that the halogen lamp irradiates heat rays more than visible light in terms of energy and that visible light can be reduced by the visible light cut filter 3.

By the way, in the conventional halogen type near infrared lighting device 30 having the above-mentioned structure, most of the light generated by the halogen lamp 1 is the visible light cut filter 3.
Since it also hits the protective glass 4 and absorbs infrared rays in addition to visible light, the visible light cut filter 3 is heated to a very high temperature and receives thermal stress. For the visible light cut filter 3, not a heat-resistant glass but an ordinary glass plate is often used.

Therefore, when a high-intensity and large-capacity halogen lamp is used to increase the illuminance of illumination light in order to enhance the illumination effect, the amount of heat radiated to the front also increases, and the heat resistance limit of the visible light cut filter 3 and the like is exceeded. In addition to giving excessive thermal stress, it may ignite, and it has been impossible to obtain a desired illuminance using a large-capacity halogen lamp.

In addition to this, the visible cut filter 3
However, it may be mechanically damaged, and in this case, the halogen light is directly irradiated, which causes dazzling of the driver of the vehicle and adversely affects the driving operation, which is a traffic safety problem.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and uses a reflecting mirror (hereinafter referred to as a semi-reflecting mirror) that reflects only the near infrared region of incident light. Then, it is an object of the present invention to propose a halogen type near-infrared illuminating device capable of using a halogen lamp having a higher capacity as a light source and thus obtaining a higher amount of light than ever. In addition, the present application also proposes a halogen type near-infrared lighting device which does not use the visible light cut filter 3 described above at all and therefore has a simple structure and is inexpensive.

[0012]

[Means for Solving the Problems] In order to solve the problems,
In the first invention of the present application, a halogen type near-infrared lighting device has a halogen lamp and a semi-reflecting mirror that reflects only a near-infrared region of incident light, and the irradiation light from the halogen lamp is passed through the semi-reflecting mirror. To illuminate the illuminated body.

Similarly, in the second invention of the present application, in the halogen type near infrared illuminating device having the above-mentioned structure, a parabolic mirror having the halogen lamp as a focal point is used as the semi-reflecting mirror.

Further, in the third invention of the present application, the halogen type near-infrared illuminating device irradiates the illuminated object through the visible light cut filter for removing the visible light component contained in the irradiation light from the halogen lamp. The illumination device includes a semi-reflecting mirror that reflects only a near-infrared region, and is configured to guide the irradiation light from the halogen lamp to the visible light cut filter via the semi-reflecting mirror.

Further, in the fourth invention of the present application, in the halogen type near infrared illuminating device of the third invention, a parabolic mirror having the halogen lamp as a focal point is used as the reflecting mirror.

[0016]

In the first and second inventions of the present application, the light emitted from the halogen lamp is incident on the semi-reflecting mirror that reflects only the near-infrared region of the incident light, and the predetermined component is absorbed or transmitted by the semi-reflecting mirror. Only the light in the near-infrared region that remains is reflected and emitted as illumination light, so near-infrared illumination can be obtained without using a visible light cut filter. It should be noted that the visible light cut filter may be used together to enhance the visible light removal effect.

In particular, in the second invention, since the parabolic mirror normally used in this type of device is provided with the characteristic as the semi-reflecting mirror, the semi-reflecting mirror is not provided separately and the same construction as the conventional one is used. Exhibits the above-mentioned action.

In the third and fourth inventions of the present application, the light emitted from the halogen lamp is incident on the semi-reflecting mirror that reflects only the near-infrared region of the incident light, and the predetermined component is absorbed or transmitted by the semi-reflecting mirror portion. Only the light in the near-infrared region, which has been left behind, is reflected and is further irradiated as illumination light through the visible light cut filter. Therefore, since heat generation in the visible light cut filter is reduced, high efficiency can be achieved by using a large-capacity halogen lamp, and at the same time, the visible light removal effect is also high.

In particular, in the fourth aspect of the invention, since the parabolic mirror normally used in this type of device is provided with the characteristic of the semi-reflecting mirror, the semi-reflecting mirror is not provided separately and the same construction as the conventional one is used. Exhibits the above-mentioned action.

[0020]

The present invention will be described in detail below with reference to the accompanying drawings. In the figure, the parts denoted by the same reference numerals as in the preceding drawings are the same or equivalent parts. FIG. 1 shows an embodiment of a halogen type near-infrared lighting device 20 corresponding to the fourth invention of the present application, wherein (a) is a sectional view and (b) is a front view.
A parabolic mirror 2A is appropriately supported in the housing 5. The parabolic mirror 2A is a reflecting mirror (described as a semi-reflecting mirror, which will be described later in detail) that reflects only the near-infrared band of incident light, unlike a normal parabolic mirror. It has a characteristic that only the light in the infrared region, which is absorbed or transmitted by the semi-reflecting mirror portion of the light other than the predetermined near-infrared band and remains, is reflected. Since it has a parabolic reflection surface, it naturally also has a converging function for reflected light. The parabolic mirror 2A also serves as a supporting portion, and the socket 7 is provided so that the halogen lamp 1 is located near the focus of the parabolic surface of the parabolic mirror 2A.
It is supported with.

The parabolic mirror 2A has a structure in which a thin film 2b is formed on the reflection surface (inward surface) of the substrate 2a, which allows the near-infrared portion (in the embodiment, the longest wave end at which the TV camera is sensitive) It mainly reflects only the band of about 1200 nm to 800 nm). Light of a shorter wavelength component including visible light of about 800 nm or less and light of a longer wavelength component of about 1200 nm or more is transmitted or absorbed and does not reflect the entire amount of light. Such a thin film formed on the reflection surface is formed by alternately laminating unit thin films of dielectrics such as titanium dioxide (TiO ₂ ) and silicon dioxide (SiO ₂ ). A vapor deposition technique can be used to form each unit thin film.

The reflection wavelength band can be changed by controlling the thickness of each of the unit thin films, and the thin film can have an appropriate reflection wavelength band according to the TV camera to be applied. For example, in the case of being compatible with an infrared TV camera, a semi-reflecting mirror having a desired characteristic in which a thin film having a characteristic suitable for infrared rays in the used band is formed is combined.

In the apparatus of the embodiment, these halogen lamps 1
A visible light cut filter 3 for removing a visible light component and a protective glass 4 for protecting the same are sequentially attached in front of (on the irradiation side of) the parabolic mirror 2A. Reference numeral 6 is a lead wire for supplying a current to the halogen lamp.

The table of FIG. 2 shows the spectral power characteristic (L) of the light generated by the halogen lamp, an example of the spectral characteristic (F) of the visible light cut filter, and the human visual sensitivity characteristic (M). In addition, the spectral reflection characteristic (R) of the parabolic mirror (semi-reflecting mirror) 2A is shown. It can be seen that visible light and long-wavelength infrared light can be reduced by a parabolic mirror (reflecting mirror), and visible light is further reduced by a visible light cut filter.

The operation of the embodiment will be briefly described below. In this halogen type near infrared lighting device 20, the halogen lamp 1
Some of the light from the visible light cut filter 3
Most of the light is incident on the parabolic mirror (semi-reflecting mirror) 2A.
Only the light that is incident on the surface of, and is reflected and condensed is incident on the visible light cut filter 3. Therefore, most of the heat rays generated from the halogen lamp 3 are absorbed by or transmitted through the semi-reflecting mirror 2A, and each portion exhibits a heat effect. That is, the heat ray absorbed by the semi-reflecting mirror 2A heats it, and the transmitted heat ray heats each absorption destination portion. As a result, the heat-generating parts due to the radiated light of the halogen lamp 1 are dispersed in each part of the halogen type near-infrared illuminating device 20, and accordingly, the heat generation and the temperature rise caused by the visible light cut filter 3 or the protective glass 4 are significantly increased. Will be reduced. The near-infrared light component, which has passed through the visible light cut filter 3 and the protective glass 4 and is removed from the visible light component, becomes a beam-like object (here, the vehicle, especially the license plate portion).
Intensively illuminate.

As described above, since the temperature rise caused by the visible light cut filter 3 and the protective glass 4 is reduced, even if the visible light cut filter 3 and the like are the same parts, the halogen lamp 1 having a higher brightness and a larger rating is provided. Can be used as a light source. This means that a highly efficient lighting device can be realized. In the present invention, even when the halogen lamp 1 is used with the same rating as the conventional one, the thermal stress on each part of the device is reduced, so that the device has a long life effect.

In the above description, an example in which a parabolic mirror that has been conventionally used for concentrating light rays is also used as a special semi-reflecting mirror according to the present application has been described, but the present invention has such a form. Not exclusively. For example, the same parabolic mirror as the conventional one that totally reflects all the components of the light beam is used, and the present invention has a flat plate shape in the optical path of the irradiation light from the halogen lamp 1 and the parabolic mirror. A configuration is adopted in which a semi-reflecting mirror 2 (flat plate mirror) that reflects only near-infrared light is arranged, and only near-infrared light reflected by this semi-reflecting mirror is irradiated as illumination light through a visible light cut filter 3 and the like. (Corresponding to the third invention of the present application, illustration is omitted).

Next, in the first and second inventions of the present application, in each of the above-mentioned halogen type near infrared illuminating devices, the visible light removing effect is obtained only by the above-mentioned semi-reflecting mirror (flat mirror or parabolic mirror) 2A. This is a halogen-type near-infrared lighting device corresponding to the configuration in which the visible light cut filter 3 is excluded. That is, in the previous embodiment, the case where the visible light cut filter 3 is arranged in the optical path from the semi-reflecting mirror 2A has been described.
This is because the visible light removal characteristics of the semi-reflecting mirror according to the present invention obtained at present are slightly insufficient for use in traffic image processing, and when used alone, the driver feels glare. However, there are some applications in which the current visible light removal characteristics of the semi-reflecting mirror 2A are sufficient, and for such applications, the halogen near-infrared lighting device can be formed by using only the halogen lamp 1 and the semi-reflecting mirror. Of course, when a semi-reflecting mirror having sufficient visible light removal characteristics is obtained, only the halogen lamp 1 and the semi-reflecting mirror (parabolic mirror or plane mirror) are used without using the visible light cut filter. It is possible to configure a halogen type near infrared illuminator that is simple in structure and applicable to small-sized traffic image processing.

As described above, also in the halogen type near infrared illuminating devices of the first and second inventions of the present application, as described above, most of the light generated by the halogen lamp 1 is incident on the semi-reflecting mirror. However, a considerable portion of the components other than the near-infrared component is removed by the semi-reflecting mirror, and only the remaining near-infrared component effective for imaging by the TV camera passes through the protective glass 4 and is irradiated. Therefore, the original purpose is achieved without the protective glass 4 being unnecessarily heated to a high temperature. That is, it is possible to use a high-intensity, large-capacity halogen lamp to increase the illuminance of the illumination light, and if the halogen lamps have the same capacity, the margin of each part of the halogen type near-infrared lighting device Is increased and the service life is extended.

In addition, in the third and fourth inventions of the halogen type near-infrared lighting device of the present invention including the visible cut filter 3, the visible cut filter 3 is mechanically damaged. Even in this case, since the visible light from the halogen light is emitted after being dimmed by the semi-reflecting mirror 2A, there is a secondary effect that it contributes to traffic safety because the glare given to the driver is reduced accordingly. ..

[0031]

As described in detail above, each of the TV camera lighting devices of the present invention has a semi-reflecting mirror that reflects only the near-infrared region of the incident light, and the light emitted from the halogen lamp is reflected by the semi-reflecting mirror. Since it is used as irradiation light through, most of the heat rays and visible light are absorbed or transmitted by this semi-reflecting mirror portion, and only the light in the infrared region remaining is reflected and irradiated as illumination light. The temperature rise in each part is reduced. As a result, it is possible to realize a higher brightness halogen type near-infrared lighting device by using a high brightness and large capacity halogen lamp as a light source. Further, when the halogen lamps have the same capacity, the margin of each part of the halogen type near-infrared lighting device is increased and the life is extended.

In the second and fourth inventions of the present application, since the parabolic mirror having the halogen lamp as the focal point is used as the semi-reflecting mirror, the above-mentioned effect unique to the present application can be obtained even though the structure is almost the same as the conventional one. be able to.

Further, according to the first and second inventions having the constitution in which the visible cut filter is eliminated, a halogen type near infrared ray illuminating device which is small-sized, inexpensive and easy to maintain can be constituted.

In the third and fourth aspects of the invention including the visible light cut filter, particularly when the visible light cut filter is mechanically damaged when used as a lighting device of a traffic image processing apparatus, halogen light is emitted. Since the visible light from the vehicle is dimmed by the semi-reflecting mirror and emitted, the glare given to the driver is reduced accordingly, which has a secondary effect of contributing to traffic safety.

[Brief description of drawings]

FIG. 1 is a side sectional view and a front view showing an embodiment of a halogen type near infrared illuminating device of the present invention.

FIG. 2 shows an example of a spectral power characteristic (L) of light generated by a halogen lamp, an example of a spectral characteristic (F) of a visible light cut filter, a human visual sensitivity characteristic (M) and a semi-reflecting mirror according to the present invention. 6 is a characteristic table showing reflection spectral characteristics (R).

FIG. 3 is a perspective view showing an example of use of a halogen type near infrared illumination device in a traffic image processing device.

FIG. 4 is a perspective view showing the appearance and installation example of a halogen type near infrared lighting device.

5A and 5B are a side sectional view and a front view showing an example of a conventional halogen type near infrared lighting device.

FIG. 6 is a characteristic table showing a spectral power characteristic (L) of light generated by a halogen lamp, an example of a spectral characteristic (F) of a visible light cut filter, and a human visual sensitivity characteristic (H).

[Explanation of symbols]

 1 ... Halogen lamp, 2 ... Semi-reflecting mirror, 2A ... Parabolic mirror (semi-reflecting mirror), 3 ... Visible light cut filter, 4 ... Protective glass.

Claims (4)

[Claims] 1. A halogen lamp (1), and a semi-reflecting mirror (2) that reflects only near-infrared region of incident light, wherein the irradiation light from the halogen lamp (1) is reflected by the semi-reflecting mirror.
A halogen type near-infrared lighting device which irradiates an object to be illuminated via (2). 2. The halogen type near infrared light according to claim 1, wherein the semi-reflecting mirror (2) is a parabolic mirror (2A) positioned with the halogen lamp (1) as a focal point. Lighting equipment. 3. A halogen type near-infrared lighting device for irradiating an illuminated object through a visible light cut filter (3) for removing visible light components contained in light emitted from a halogen lamp (1), A halogen type near infrared illuminating device characterized in that irradiation light from a lamp (1) is guided to the visible light cut filter (3) through a reflecting mirror (2) which reflects only a near infrared region. 4. The halogen lamp is used as the reflecting mirror (2).
The halogen type near-infrared lighting device according to claim 4, which is a parabolic mirror (2A) positioned with (1) as a focal point.