JPH07307108A - Near infrared lighting device - Google Patents

Abstract

PURPOSE:To suppress the temperature rise of a near infrared transmission filter disposed in an irradiated surface by using a high-intensity type (short arc type) xenon lamp as the light source of a near infrared lighting device even in a high output light source. CONSTITUTION:A high-intensity type xenon lamp is used for the light source 11 of a near infrared lighting device. A reflecting mirror 12 covered with an optical coating film 13 which reflects only near infrared light of not less than 700nm and transmits light of not more.than 700nm is disposed in the vicinity of the light source 11, and the irradiation of near infrared light is performed through a near infrared transmission filter 5 provided on the opening side of a casing 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-infrared illuminating device, and more particularly to a high-power near-infrared illuminating device having a strong line spectrum in the near-infrared portion which cannot be sensed by humans.

[0002]

2. Description of the Related Art Conventionally, in order to prevent an intruder from recognizing the existence of the position of the image pickup camera for illumination of an image pickup camera for crime prevention in a bank, a house, etc., a near-infrared light which cannot be sensed by a human is irradiated onto the subject position. A near-infrared illuminating device as described above is disclosed in JP-A-62-25.
It is known and disclosed in Japanese Patent No. 5829.

The above-mentioned near infrared lighting device uses a high pressure discharge lamp, a high pressure halogen lamp or the like. In such a conventional near-infrared lighting device, the temperature rise is large and the filter glass or the like is deformed, so that the temperature rise is suppressed, and a high-output, long-life near-infrared lighting device is obtained. The configuration will be described with reference to FIG.

In the figure, reference numeral 1 denotes a near-infrared illuminating device as a whole, and reference numeral 2 denotes a reflecting shade. The reflecting shade 2 is rotatable around a rotary shaft 8 and is pivotally attached to a support base 3. . Reference numeral 4 denotes a halogen lamp as a light source. A near-infrared transmission filter 5 that transmits near-infrared rays is provided on the front surface side of the reflection shade 2,
A cold mirror coating 6 is provided on the rear surface of the near-infrared transmission filter 5 on the light source 4 side so as to reflect a wavelength of light of 700 nm or less and transmit a wavelength of near-infrared light of 800 nm or more. Reference numeral 7 is a protective glass disposed on the front side of the near infrared transmission filter 5.

According to the near-infrared illuminating device 1 described above, since the cold mirror 6 is provided on the light source 4 side of the near-infrared transmitting filter 5, light of 700 nm or less is reflected to the light source 4 side and the near-infrared transmitting filter 5 The thing which can suppress the temperature of 300 degreeC or less is obtained.

[0006]

In the near-infrared illuminating device 1 described in the above-mentioned conventional configuration, a halogen lamp or a sodium lamp is used as the light source 4, but these lamps have a large light source 4 and near-infrared light. However, there was a problem that the efficiency of the light emission output was poor.

Further, in the above-mentioned near-infrared illuminating device, light having a wavelength of 700 nm or less emitted from the halogen lamp 4 of the light source is cut by using the cold mirror film 6 arranged immediately before the infrared transmission filter 5. However, the reflection efficiency of this cold mirror coating 6 is about 80% at maximum, and therefore,
20% emitted from the halogen lamp 4 is absorbed by the near-infrared transmission filter 5, and even if the halogen lamp 4 of 1 kW is used, the temperature of the near-infrared transmission filter 5 reaches 300 ° C., and the light source has a large output. There was a problem that I could not do.

The present invention is intended to provide a near-infrared illuminating device which solves the above-mentioned problems, and it is possible to suppress the temperature rise of the near-infrared transmitting filter 5 as low as possible even if a high-power light source is used. It is intended to obtain a near-infrared lighting device having high light-collecting efficiency and good near-infrared emission efficiency.

[0009]

As shown in FIG. 1, the near-infrared lighting device of the present invention has a light source 11 using a high-intensity xenon lamp and a light source 11 disposed near the light source 11.
A reflecting mirror 12 provided with an optical coating 13 that reflects only near-infrared light emitted from the light source 11 and transmits other wavelengths;
It is provided with a near-infrared transmission filter 5 that transmits only near-infrared light from the light source 11 and the reflecting mirror 12.

[0010]

Since the near-infrared lighting device of the present invention uses a high-intensity type xenon lamp as a light source, it is extremely small, such as a few millimeters, and is close to a point light source, so that an optical condensing efficiency can be obtained. Not only that, it has a strong line spectrum in the near-infrared region, and a large emission can be obtained in the near-infrared region of 800 to 1000 nm. Furthermore, since a reflecting mirror that reflects only near-infrared light is used in the vicinity of the high-intensity xenon lamp of the light source, the heat rays absorbed by the near-infrared filter arranged in front of the light source can be extremely reduced, Even if a large-capacity light source is used, it is possible to obtain a near-infrared lighting device that can suppress the temperature rise of the near-infrared transmission filter to an extremely low level.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the near infrared illumination device of the present invention will be described below with reference to FIGS. FIG. 1 is a side cross-sectional view and a back view of a part of the near-infrared lighting device of the present invention, FIG. 2 is a spectral characteristic diagram of a xenon lamp used as a light source, and FIG. 3 is an optical characteristic of a reflecting mirror. The figure is shown.

An embodiment of the near infrared illuminating device will be described in detail with reference to FIG. Reference numeral 1 generally indicates the near-infrared lighting device of this example. Generally, the wavelength range as near infrared light is 70
It is about 0 nm to 3000 nm, and the description will proceed in this example as a near-infrared illuminating device configured to emit near-infrared light in this wavelength range. The parts corresponding to those in FIG. 4 are designated by the same reference numerals.

The casing 10 of the near-infrared lighting device 1 is made of metal in a substantially funnel shape, and has a large surface area so that heat is sufficiently radiated from the surface of the casing 10.
Although not shown in FIG. 1, fins or the like for heat dissipation may be provided. A front surface of the funnel-shaped casing 10 is formed as an opening, and a disk-shaped protective glass 7 is provided in the front opening, and a disk-shaped near-infrared transmission filter 5 is arranged on the rear surface of the protection glass 7. There is. Reference numeral 5 is a near-infrared transmission filter having an optical property of transmitting only near-infrared light of 700 nm or more. Of course, not only the protective glass 7 but also a glass having an optical property of transmitting a near-infrared light is selected.

A light source 1 is provided at a substantially intermediate position of the casing 10.
1 is provided. As the light source 11, a high brightness type (short arc type) xenon lamp is used. This short arc type xenon lamp is a quartz discharge tube having an arc length of about 1 to 2 mm, filled with xenon gas of about 6 atm at room temperature, and has an average brightness of about 10 ^{4 to} 9 × 10 ⁴ cd / cm ² . High brightness can be obtained. The short arc type xenon lamp having a rated lamp power of about 75 W to 30 KW is commercially available.

The spectral distribution of such a xenon lamp is shown in FIG.
Shown in. That is, the spectral distribution ranges from the ultraviolet light region to the visible light region 2
700 nm or less up to 0a is a continuous spectrum similar to natural daylight, and has a strong line spectrum in the near infrared light region 20b of 700 nm or more. It is also known that this spectral characteristic hardly changes even if the input voltage (rated input) is increased.

The short arc type xenon lamp 11 is arranged at a central position substantially in the middle of the casing 10 with its longitudinal direction directed toward the front and back sides of the casing 10 so as to cover the short arc type xenon lamp 11. The half-moon type reflecting mirror 12 is locked in the casing 10 by a predetermined method so that the half-moon type reflecting mirror 12 is arranged on the casing 10. The half-moon type reflecting mirror 12 has a through hole 18 at a substantially central position, and one end of the xenon lamp 11 is inserted and held in the through hole 18. Further, the xenon lamp 11 is moved back and forth (in the direction of arrow AB) so that the depth of focus can be adjusted. Since this adjusting mechanism is widely used in lighting devices, a specific configuration thereof will be omitted, but the xenon lamp 11 can be finely adjusted in the AB direction by rotating the adjusting screw 15 protruding to the rear portion of the casing 10. Has been done.

Reference numeral 17 denotes a connecting portion for connecting to an external power source, and 14 denotes a handle protruding rearward from an upper side of a substantially central position of the casing 10, and a groove 19a is provided on a lower side of the central position of the casing 10 from rearward to frontward. Is formed on the support base 3 for holding the casing 10.
It is designed to be held in.

The semi-circular reflecting mirror 12 of this example is an optical device that reflects near infrared light of 700 nm or more on its inner surface and transmits other wavelengths of 700 nm or less, as shown by an optical characteristic curve 21 in FIG. Since the coating 13 is formed, near-infrared light of 700 nm or more emitted from the short arc type xenon lamp 11
0b is reflected by the optical coating 13 of the semicircular reflecting mirror 12,
Only the near-infrared light having a strong spectrum is emitted through the near-infrared transmission filter 5 and the protective glass 7 arranged in front of the casing.

Further, the light 20a emitted from the short arc type xenon lamp 11 from the ultraviolet region of 700 nm or less to the visible light region is transmitted through the optical coating 13 and the reflecting mirror 12, and is absorbed by the casing 10 to be absorbed by the casing 10. Heat is dissipated from the surface.

When such a near-infrared lighting device of this example is used for a lighting device such as a security near-infrared camera, the near-infrared light emitted from this near-infrared lighting device is recognized by the human eye. Since it is not possible, it can be configured so that the near infrared camera position cannot be recognized.

Since the near-infrared lighting device of the present invention uses a high-intensity type (short arc type) xenon lamp as a light source instead of a halogen lamp or a sodium lamp as in the conventional case as described above, it is strong at 800 nm to 1000 nm. It emits near-infrared light, and since the light emitting source is a few millimeters, which is close to that of a point light source, it is possible to obtain an extremely high optical condensing efficiency.

Further, in the conventional structure, the temperature of the near infrared transmitting filter is 3 when a 1 kW halogen lamp is used as a light source.
Although reaching a high temperature of 00 ° C., the near-infrared lighting device of the present invention has a spectral characteristic other than near-infrared light shown in FIG.
Light 20a having a wavelength in the range from ultraviolet light to visible light below nm
Is not radiated to the front where the near-infrared transmission filter 5 is arranged, so that the temperature rise of the near-infrared transmission filter 5 when using a 1 KW high-intensity xenon lamp can be maintained at about 100 ° C. As a result, the heat rays absorbed by the near infrared transmission filter can be reduced.

Further, it was confirmed that the irradiation distance when the high-intensity xenon lamp 11 having an output of 150 W was used was equivalent to that of the conventional halogen lamp of 1 KW or more.

[0024]

According to the near-infrared lighting device of the present invention, the temperature rise of the near-infrared transmission filter can be suppressed as low as possible even if a high-power high-intensity xenon lamp is used, and a conventional halogen lamp of the same output, etc. It is possible to reduce the temperature rise to about 1/3 compared to the above, and it is possible to obtain a near-infrared lighting device with a irradiation distance equivalent to that of a high-output halogen lamp even with a low-output high-luminance xenon lamp. A highly useful infrared searchlight can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a near-infrared lighting device of the present invention.

FIG. 2 is a spectral characteristic diagram of a xenon lamp used in the near-infrared lighting device of the present invention.

FIG. 3 is an optical characteristic diagram of a reflecting mirror of the near-infrared lighting device of the present invention.

FIG. 4 is a side view of a conventional near infrared lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Near-infrared lighting device 3 Support stand 5 Near-infrared transmission filter 10 Casing 11 Light source (xenon lamp) 12 Reflector 13 Optical coating

Claims (1)

[Claims] 1. A light source using a high-intensity xenon lamp, and an optical coating disposed near the light source, which reflects only near-infrared light emitted from the light source and transmits other wavelengths. A near-infrared illuminating device comprising: a reflecting mirror; and a near-infrared transmission filter that transmits only near-infrared light from the light source and the reflecting mirror.