JP2006019331A - Infrared illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared lighting system which can emit infrared ray with uniform brightness. <P>SOLUTION: The infrared lighting system is provided with an LED unit 15 wherein a plurality of infrared LEDs 11 are attached onto a substrate 13, an LED driving circuit 16 to drive the infrared LEDs 11 and a power supply 17 to supply to the LED driving circuit 16 and electric power for driving the infrared LEDs 11. All or a part of the infrared LEDs 11 is arranged in a manner that the light emitting surface of the respective infrared LED is inclined against the surface of a substrate. A plurality of projections 18 are provided on the arrangement surface of infrared LED on the substrate 13, and the bottom of the respective light emitter of the infrared LEDs 11 is brought into contact with any of the projections 18, thereby allowing the respective light emitting surface of the infrared LED 11 to be inclined against the surface of the substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an infrared illumination device suitable for use in combination with an infrared camera such as a security camera, a night observation camera, a traffic monitoring camera, and a parking lot monitoring camera.

  2. Description of the Related Art Conventionally, an infrared illumination device used in combination with an infrared camera, which uses a plurality of infrared LEDs (light emitting diodes) as light sources, is known. In particular, a panel-shaped light source in which a large number of LEDs are arranged in a matrix, for example, has a large amount of light as a whole, and is used as various types of illumination. On the highway, as shown in FIG. 8, the light source 10 used to illuminate the traveling vehicle 20 and photograph a license plate or the like as needed is also provided with a plurality of LEDs on a substrate using an attachment device. The ones arranged in a vertical and horizontal order are used.

  In the LED, a spherical or aspherical lens (top) of a translucent member covering the LED element has a bullet shape, and its light distribution characteristic is shown in FIG. FIG. 7B is a plan view of FIG. As shown in FIGS. 7A and 7B, the infrared light emitted from the LED 11 of the translucent member has a light distribution characteristic having a ring-shaped dent 12A that captures an image of the LDE chip on the irradiation surface 12. May be indicated. As shown in FIG. 7C, the LED unit formed by orderly integrating a plurality of these LEDs on a predetermined substrate also has a waveform light distribution characteristic on the irradiation surface 12 when the synthesized infrared light is emitted. Indicates.

Therefore, when such a conventional LED unit is used as, for example, a photographing illumination device, the light distribution characteristic is in the shape of a wave, so that uneven brightness may occur and a desired image quality may not be obtained. Therefore, it is not preferable. In order to prevent unevenness in luminance, it is desirable that light emitted from a plurality of LEDs has a light distribution characteristic that is as flat as possible.
An LED unit in which a plurality of LEDs are arranged in an orderly manner on a predetermined substrate cannot be made into flat illumination.
Also, as the distance from the light source to the subject increases, the irradiation light diffuses and the light intensity decreases, so the light emission intensity of the LED itself must be increased. However, when the emission intensity of the LED itself is increased, the heat generation of the LED increases, the life of the LED is shortened, and the power consumption of the illumination is increased.

By the way, LED infrared illuminating devices in which a plurality of LEDs are arranged on a substrate to obtain flat light distribution characteristics are known (see, for example, Patent Document 1 and Patent Document 2).
The illuminating device of patent document 1 uses reflection type LED, and inclines the irradiation angle of the LED unit formed by integrating these on a board | substrate with respect to the orthogonal axis of a board | substrate, respectively. Moreover, the illumination device of Patent Document 2 is configured to supply a constant current having a value smaller than that of the outer LED unit to the inner LED unit among the plurality of LED units.

Japanese Patent Laid-Open No. 11-195307 Japanese Patent Laid-Open No. 11-195317

The above conventional techniques have the following problems to be solved.
Since the illumination device of Patent Document 1 uses a reflective LED, the directivity of light is large and the central luminance is large. For this reason, when the reflective LEDs are assembled to form a surface emitting LED unit, the central luminance of the LED unit itself also increases due to light interference.
From this, when the LED units are arranged in a plane to form a surface light emitter and an attempt is made to obtain a flat light distribution characteristic, the LED units cannot be directed in the condensing direction, and the LED units are arranged in the dispersion direction. It is necessary to tilt, and the light collection efficiency is considered to deteriorate.

The illuminating device of Patent Document 2 adjusts the current value and time passed for each LED unit to obtain a flat light distribution characteristic, but is considered to have the following problems. That is,
-The specification characteristics of the LED itself cannot be fully exhibited.
-The outer LED unit tends to increase the current and time to flow.
・ Electric circuit becomes complicated.

  The present invention has been made paying attention to the above points, and an object of the present invention is to provide an infrared illumination device capable of obtaining a flat shape light distribution characteristic with a simple structure.

The present invention adopts the following configuration in order to solve the above points.
<Configuration 1>
An LED unit having a plurality of infrared LEDs mounted on a substrate; an LED driving circuit for driving the infrared LEDs; and a power source for supplying power for driving the infrared LEDs to the LED driving circuit; An infrared illumination device, wherein all or a part of the plurality of infrared LEDs are arranged such that a light emitting surface of each infrared LED is inclined with respect to the substrate surface.

  By varying the direction of the light emitting surface of each infrared LED, the non-uniform irradiation surface emitted from the infrared LED alone is synthesized, and the irradiation surface of uniform brightness as a whole, and also the extended irradiation surface Is obtained.

<Configuration 2>
In the infrared illumination device according to Configuration 1, a plurality of protrusions are provided on a surface of the substrate on which the infrared LED is disposed, and a bottom surface of each light emitting portion of the plurality of infrared LEDs is contacted with any of the plurality of protrusions. An infrared illumination device, wherein the light emitting surfaces of the infrared LEDs are in contact with each other and inclined with respect to the substrate surface.

One projection is used for one infrared LED, and the light emitting surface of each infrared LED is inclined at a predetermined angle.
The position and size of each protrusion are determined by calculation using a computer or the like according to the light emission performance of each infrared LED used in advance, and are provided on a predetermined surface of the substrate as designed.

<Configuration 3>
The infrared illuminating device according to Configuration 1 or 2, wherein the plurality of infrared LEDs are divided into a plurality of groups and are inclined on the substrate at different angles for each group. .

  Each group does not need to be grouped and may be located apart. Since the distance from the illumination device to the predetermined irradiation surface is 5 to 10 m, the positional relationship between the single infrared LEDs of the illumination device can be substantially ignored.

<Configuration 4>
The infrared illumination device according to Configuration 2, wherein the protrusion is formed on the substrate with a curable resin.

  The protrusions are formed on a substrate with a curable resin having insulating properties and adhesive properties such as an epoxy resin so that the height is randomly about 0.2 mm. Even if a large number of LEDs are automatically mounted on a substrate using an automatic machine, the surface of the substrate is uneven due to a large number of protrusions, so that each LED can be mounted in a state of being tilted apart.

<Configuration 5>
5. The infrared illumination device according to any one of configurations 2 to 4, wherein the protrusion is formed on the substrate by printing.

  The protrusions are formed by, for example, printing on a substrate with a thickness of about 50 to 100 μm by silk printing. Since the outer diameter of the infrared LED is about 5 mm, the LED shaft can be tilted about 1 degree with respect to the substrate by a protrusion having a thickness of about 50 to 100 μm. By printing, a protrusion having a predetermined shape can be easily formed at an arbitrary position. In addition, the illumination area can be expanded without adjusting the tilt of the substrate. In the silk printing, when the inclination is insufficient, printing of an epoxy resin or the like on the substrate is effective.

    Hereinafter, embodiments of the present invention will be described using specific examples.

FIG. 1 is an explanatory diagram illustrating a configuration of the infrared illumination device according to the first embodiment.
In FIG. 1, the infrared illumination device includes an LED unit 15 in which a plurality of infrared LEDs 11 are mounted on a substrate 13. All or part of the infrared LEDs 11 of the LED unit 15 are arranged with the light emitting surfaces of the infrared LEDs inclined with respect to the upper surface of the substrate. In addition, as shown in FIG. 2, the LED unit 15 is connected to a circuit for lighting and driving the plurality of infrared LEDs 11. This circuit includes an LED unit 15, an LED drive circuit 16, and a power supply 17. A predetermined current is supplied from the LED drive circuit 16 to all the infrared LEDs 11 mounted on the substrate 13. Thereby, each infrared LED 11 irradiates infrared rays.

  The drive current of the LED drive circuit 16 is controlled so that the light emission intensity is stabilized, for example, depending on the state of the infrared LED 11. For this purpose, a control circuit is provided in the LED drive circuit 16. Moreover, a cooling fan is provided as needed, and all the infrared LEDs 11 mounted on the LED unit 15 are cooled by wind. The power source 17 is a power source for operating the LED drive circuit 16 and the control circuit.

FIG. 3 is a front view showing a specific example of the LED unit 15.
As shown in FIG. 3, a plurality of protrusions 18 are provided on the surface 13A of the substrate 13 on which the infrared LED 11 is disposed, and the bottom surface of each light emitting portion of the infrared LED 11 is brought into contact with the light emitting surface of the infrared LED 11 to form the substrate surface 13A. It is made to incline with respect to. Each protrusion 18 is formed in a mountain shape having a height of about 0.2 to 0.5 mm by a curable resin having insulating properties and adhesive properties such as an epoxy resin. The infrared LED 11 is fixed to the substrate 13 by inserting two lead frames 14 through a through hole 19 formed in the substrate 13 and soldering them.
The thickness (height) of the resin printing can be easily controlled by the metal mask thickness according to the inclination of the infrared LED 11. In addition, the light distribution performance in the vertical direction or the horizontal direction can be controlled to some extent independently depending on the printing position.

FIG. 4 is a plan view showing a part of the substrate 13.
In FIG. 4, a substrate 13 has an electric circuit for forming a predetermined wiring pattern in advance, a large number of through holes 19 through which two lead frames 14 are inserted in order to arrange several hundred infrared LEDs 11 vertically and horizontally, Projection 18 is provided. One protrusion 18 is provided around each through-hole 19 for each infrared LED 11, and the light emitting surface of each infrared LED is inclined at a predetermined angle. The position and size of each protrusion are determined by calculation with a computer or the like according to the light emission performance of each infrared LED 11 and are provided on a predetermined surface of the substrate as designed using a manufacturing technique such as mask printing.

The plurality of infrared LEDs 11 may be divided into a plurality of groups, and may be disposed on the substrate 13 by being inclined at different angles for each group.
For example, it is assumed that 100 infrared LEDs constituting the LED unit are divided into 5 groups each having 20 pieces. Of these, the first group is assumed to have an inclination angle of 0 degree, that is, no inclination. The second group has a tilt angle of 2 degrees, the third group has a tilt angle of 3 degrees, the fourth group has a tilt angle of 4 degrees, and the fifth group has a tilt angle of 5 degrees. Deploy. Each group does not need to be grouped and may be located apart. Since the distance from the illumination device to the predetermined irradiation surface is 5 to 10 m, the positional relationship between the infrared LEDs alone of the illumination device can be substantially ignored.

  FIG. 5 shows the light distribution characteristics of the infrared illumination device. As shown in FIG. 5, the infrared light emitted from the LED unit 15 exhibits a flat light distribution characteristic on the irradiation surface 16. An LED unit in which a plurality of LEDs are arranged on a predetermined substrate cannot be made flat illumination as shown in FIG. 7B, but a plurality of LEDs are arranged in an inclined manner so that an infrared LED alone The non-uniform irradiation surfaces emitted from the two are combined to form an irradiation surface with uniform brightness as a whole, that is, flat illumination. Therefore, when such an LED unit 15 is used as, for example, a photographing illumination device, the light distribution characteristic is a flat shape, so that luminance unevenness does not occur and a desired image quality can be obtained.

  Further, as shown in FIG. 5, the direction of the light emitting surface of each infrared LED is made different, and the direction of the light emitting surface is adjusted so that the irradiation surface has a uniform brightness as a whole and desired on both sides. The irradiation surface expanded to the width H of the first is obtained. That is, the illumination area can be expanded without adjusting the tilt of the substrate.

FIG. 6 is a diagram illustrating the configuration of the infrared illumination device according to the second embodiment.
As shown in FIG. 6, in this embodiment, the protrusion 18 </ b> A provided on the substrate 13 is formed on the upper surface of the substrate 13 by printing, for example, silk printing, and corresponds to the infrared LED 11. The protrusion 18A is formed to a thickness of about 50 to 100 μm. Since the outer diameter of the infrared LED is about 5 mm, the axis of the LED 11 can be tilted about 1 degree with respect to the substrate 13 by a protrusion having a height of 50 to 100 μm.
Since the other configuration except that the protrusion 18A is configured by printing is the same as that of the first embodiment, a duplicate description is omitted.

It is a perspective view which shows the structure of the infrared illuminating device of Example 1. FIG. It is a block diagram of the circuit which lights and drives the infrared LED of Example 1. FIG. 3 is a front view showing a specific example of an LED unit of Example 1. 3 is a plan view showing a part of the substrate of Example 1. FIG. It is explanatory drawing which shows the light distribution characteristic of the infrared illuminating device of Example 1. FIG. It is a figure which shows the specific example of the infrared rays illuminating device of Example 2, (a) is a front view of an LED unit, (b) is the same top view. It is explanatory drawing which shows the light distribution characteristic of the conventional infrared illuminating device. It is explanatory drawing which shows an example of the infrared illuminating device used in combination with an infrared camera.

Explanation of symbols

11 Infrared LED
13 Substrate 14 Lead frame 15 LED unit 16 LED drive circuit 17 Power supply 18 Protrusion 19 Through hole

Claims (5)

An LED unit formed by mounting a plurality of infrared LEDs on a substrate;
An LED drive circuit for driving the infrared LED;
A power supply for supplying power for driving the infrared LED to the LED drive circuit,
An infrared illumination device, wherein all or a part of the plurality of infrared LEDs are arranged such that a light emitting surface of each infrared LED is inclined with respect to the substrate surface. The infrared illumination device according to claim 1,
A plurality of protrusions are provided on the surface of the substrate on which the infrared LED is disposed,
An infrared ray characterized in that a bottom surface of each light emitting portion of each of the plurality of infrared LEDs is brought into contact with any one of the plurality of protrusions so that each light emitting surface of the infrared LED is inclined with respect to the substrate surface. Lighting device. In the infrared illumination device according to claim 1 or 2,
The infrared illumination device according to claim 1, wherein the plurality of infrared LEDs are divided into a plurality of groups and are inclined on the substrate at different angles. The infrared illumination device according to claim 2,
An infrared illumination device, wherein the protrusion is formed on the substrate with a curable resin. In the infrared illumination device according to any one of claims 2 to 4,
An infrared illumination device, wherein the protrusion is formed on the substrate by printing.

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