JP2003168309A - Light source device for light guide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve miniaturization and a cost reduction by improving efficiency in light guiding, as for a light source device to bring light into an optical fiber. <P>SOLUTION: Light from a light source comprising a plurality of LEDs is condensed toward the incident end surface of an optical fiber by a Fresnel lens. A reflector to reflect light which does not enter into the incident end surface of the optical fiber is provided in a region around the incident end surface of the optical fiber. Reflected light reflected by the reflector is diffusedly reflected by a diffusible reflecting surface formed in the non-emissive region of the light emitting source. The light from the light emitting source can be efficiently taken into the optical fiber by making the diffusedly reflected light enter again into the incident end surface of the optical fiber. In addition, a collimating lens is provided adjacently to the front of each LED. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide light source device for introducing light emitted from a light emitting source into an optical fiber, and more specifically, for a light guide using a light emitting diode (LED) as a light emitting source. The present invention relates to a light source device.

[0002]

2. Description of the Related Art In recent years, in various manufacturing factories, agricultural product sorting factories, and the like, inspection devices using photographed images by CCD cameras or the like have been used to find defective products and noncompliant products. In such an apparatus, in order to accurately obtain a desired image with a CCD camera or the like, it is necessary to provide optimum illumination suitable for the purpose. As one of such illuminations, an illumination device that guides light using an optical fiber and irradiates a desired portion is known. As a light guide light source device for sending light to an optical fiber in such a lighting device, a light source using a halogen lamp has been the mainstream conventionally, but in recent years, ease of maintenance and the need for a monochromatic wavelength are required. LEDs are being developed as light emitting sources because of their advantages such as low cost due to their efficiency and luminous efficiency.

An example of this type of light guide light source device using an LED as a light source is, for example, Japanese Patent Laid-Open No. 11-21960.
Those described in Japanese Patent No. 8 and Japanese Patent Laid-Open No. 2001-84819 are known.

For example, in the light guide light source device described in the former document, the light from the LED is condensed by a concentrating member having a reverse trumpet shape, and the light of the LED reaches the optical fiber. However, the light emitted from the LED is not an ideal collimated light and has a considerable spread. Therefore, the angle at which the light traveling toward the incident end face of the optical fiber reaches the incident end face while being reflected by the inner surface of the light condensing member has a considerably wide range. The angle of light that can enter the optical fiber is approximately ±
Since it is within 35 °, most of the light collected by the condensing member cannot enter the optical fiber, and even if it can be incident, the light incident at an angle of ± 35 ° or more leaks to the outside on the way, The light is not guided to the exit end face side.

On the other hand, in the light source device for a light guide described in the latter document, a plurality of LEDs are arranged in a ring shape so as to be directed to the same surface side and surround the light lead-out hole, and a concave mirror is provided at a position facing the light guide hole. It is provided. One end of the optical fiber is inserted into the light guide hole so that the light reflected by the concave mirror is applied to the incident end surface of the optical fiber. Furthermore, in order to compensate for the decrease in the illuminance near the center of the overlapping illuminated surfaces due to the annular arrangement of the LEDs, the LE facing the light exit hole is located near the center of the concave mirror.
D is arranged so that the light emitted from this LED is directly introduced into the incident end face of the optical fiber.

[0006]

One of the greatest demands for an illuminating device using such a light source device for a light guide is to obtain a high illuminance at a desired portion such as an object to be inspected. For that purpose, it is important to increase the light emission intensity of the light emitting source itself and to efficiently enter the light emitted from the light emitting source into the optical fiber. In the latter light source device for a light guide, a concave mirror is used in order to improve the incidence efficiency of light to the optical fiber, but in reality, the illuminance is not always satisfactory because of the following problems. I could not secure.

First of all, the light emitted from an LED is not ideally parallel light and has a considerable spread. Therefore, if it is attempted to reflect all such divergent light by the concave mirror, it is necessary to use a very large concave mirror, which hinders downsizing of the device and is costly. Further, even if the cost can be ignored and all the light emitted can be reflected by the concave mirror, the light-collecting area after reflection by the concave mirror also greatly expands, and as a result, part of the reflected light does not enter the optical fiber.

The second problem is that even if the light reflected by the concave mirror is properly collected and strikes the incident end face of the optical fiber and is taken into the inside of the optical fiber, all of the light is guided to the exit end of the optical fiber. The point is that it does not become effective light. That is, unless the angle of incidence (angle formed by the incident light with the central axis of the optical fiber) with respect to the incident end face of the optical fiber is less than or equal to a predetermined angle, the light entering the inside of the optical fiber is not reflected by the inner peripheral surface of the optical fiber. It is not sent in the direction of the ejection end. Therefore, even if light is incident on the incident end surface of the optical fiber, part of the light is not guided to the exit end.

The poor efficiency of incidence on the optical fiber as described above not only makes it difficult to obtain high illuminance on the irradiation side, but if the same illuminance is to be obtained, it is necessary to increase the number of LEDs. Occurs. Then, in addition to the high cost, downsizing becomes difficult, and further, since the heat generated from the LED increases, a cooling device such as a fan and the like need to be large, which is disadvantageous.

The present invention has been made to solve such problems, and its main purpose is to:
An object of the present invention is to provide a light guide light source device capable of intensively irradiating an object with light of high illuminance at a relatively low cost by making light emitted from a light source enter an optical fiber more efficiently. .

[0011]

The gist of the light source device for a light guide of the present invention is a light source device for a light guide for sending light from an incident end face of an optical fiber to the inside thereof, and a light emitting source, A condenser lens that collects the light from the light emitting source toward the incident end surface of the optical fiber, and a light collecting lens that is provided in a region around the incident end surface of the optical fiber and reflects light that does not enter the incident end surface of the optical fiber toward the light emitting source. With a reflector
And a diffuse reflection surface which is formed in a non-emission area of the light emitting source and diffuses and reflects the reflected light from the reflecting mirror.

With this structure, the light that has deviated from the incident end face of the optical fiber is reflected by the reflecting mirror toward the light emitting source, and is diffusely reflected by the diffuse reflection surface formed in the non-light emitting region of the light emitting source. . A part of the diffusely reflected light is incident on the incident end face of the optical fiber and introduced into the optical fiber. That is, the effect that light is emitted from the non-light emitting region of the light emitting source is produced, and more light is taken into the optical fiber, so that efficient incidence can be obtained.

As one mode of the light source device for a light guide according to the present invention, the light emitting source is a plurality of light emitting diodes arranged on a surface substantially parallel to the incident end surface of the optical fiber, and the light emitting diodes are arranged in front of the respective light emitting diodes. The collimator lens provided as described above may be provided as a pair. Therefore, the divergent emitted light from the light emitting diode is converted into parallel light by the collimator lens, and then is converged by the condenser lens so as to be within the incident aperture angle of the optical fiber. Of course, the transparent resin body itself that molds the light-emitting body (chip) of the light-emitting diode that is the light-emitting source may be processed into a tip bullet shape or other shape so as to have the lens effect.

Further, the diffuse reflection surface is characterized in that it is provided on the surface of the lens holder that supports the collimating lens (the surface facing the incident end surface of the optical fiber). There are various methods for forming a diffuse reflection surface, but for example, a method of applying a white diffusion paint such as magnesium oxide or barium sulfate is preferable.

The condenser lens is preferably a Fresnel lens in addition to a general convex lens. A Fresnel lens is made by pressing or injection molding acrylic resin, dividing a convex lens into concentric circles, and arranging them flat.It is a plate-shaped lens with several circular grooves formed around its center point. It has the advantage of being thin, light and easy to mold.

The light thus made substantially parallel by the collimator lens is condensed by the condenser lens and the incident end face of the optical fiber is focused on the focal point of the condenser lens (including the vicinity of the focal point).
The light from the light emitting source can be incident on the incident end face of the optical fiber by disposing the light source.

However, not all the light from the light emitting source is incident on the incident end face of the optical fiber. Part of the light from the light emitting source is also radiated to the region around the incident end face. According to the present invention, in order to reuse the light emitted to this portion, a reflecting mirror is provided in the area around the entrance end face of the optical fiber, and the light reflected from the reflecting mirror is diffused and reflected in the non-light emitting area of the light emitting source. A diffuse reflection surface is provided. As a result, the light that does not enter the incident end surface of the optical fiber (light in the area surrounding the incident end surface of the optical fiber) is reflected by the reflecting mirror, this reflected light is diffused and reflected by the diffuse reflection surface, and part of the diffuse reflected light is reflected. It is incident on the optical fiber.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the principle configuration of a light guide light source device according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the light guide light source device according to the present embodiment taken along a plane including an axis C, showing a state in which light emitted from a light source is incident on an incident end face of an optical fiber. FIG. 2 is a diagram showing how the light irradiated to the area around the incident end face of the optical fiber is incident on the incident end face of the optical fiber by reflection and diffuse reflection. Axis C
Is the central axis of the optical fiber 5 into which light is introduced. FIG. 3 is a plan view of the light emitting source 2 of the present invention viewed from the incident end face side of the optical fiber. 1 and 2, only a typical optical path (light incident on the optical axis of the incident end face of the optical fiber) is shown in order to avoid making the drawings complicated, but many other than the described ones. It is natural that there is light passing through the optical path of.

The light source device 10 for a light guide according to the present invention comprises a cylindrical main body 1 having openings at both ends, which is made of an integrally molded product of metal such as aluminum or synthetic resin, and a light emitting source 2 housed in the main body 1. Similarly, a Fresnel lens 3 as a condenser lens housed in the main body, a cover plate 4 for closing one opening end of the main body 1, an optical connector 6 of an optical fiber 5 attached to the cover plate 4, and an inner surface of the cover plate 4 And the incident end face 5 of the optical fiber 5
The reflecting mirror 7 is provided in a region around a.

The light emitting source 2 includes a substrate 21 provided perpendicularly to the axis C, a plurality of light emitting diodes (hereinafter referred to as LEDs) 22 arranged on the substrate 21 including the axis C, and each LED.
Collimating lenses 23 provided near the front of 22 respectively
It consists of

Each LED 22 is formed by molding a chip, which is a light emitting body, with a transparent body such as resin or glass, and a substrate so that the axis (optical axis) of light emitted from the LED is parallel to the axis C. It is fixed at 21. It is preferable that the LED 22 has a light emission intensity as high as possible, and that the light spread angle is narrow. However, many of the ones with high emission intensity have a wide beam divergence angle. Therefore, it is effective to use the collimator lens 23 so that the light emitted from the LED 22 while being spread in various directions is condensed and becomes substantially parallel light along the axis C.

The collimator lens 23 is fitted and fixed in a number of mounting holes 24a of a lens holder 24 made of aluminum or synthetic resin material. A white paint is applied to the non-light emitting area (the portion other than the mounting hole 24a of the collimating lens 23) on the surface of the lens holder 24 (the surface facing the incident end surface 5a of the optical fiber 5), and the diffuse reflection surface 8 (FIG. 3). A large number of black dots).

The lens holder 24, together with the substrate 21, is an LED.
It is screwed to an aluminum mounting plate 25 for dissipating the heat generated by 22. The light emitting source 2 is fixed to the other open end of the main body 1 facing the reflecting mirror 7 by fixing its mounting plate 25 with screws (not shown).

The Fresnel lens 3 is screwed (not shown) to the lens holder 24 via the support ring 9.
Light emitted from the light emitting source 2 and parallel to the axis C passes through the Fresnel lens 3 and is condensed at the focal position. By arranging the incident end surface 5a of the optical fiber 5 at this focus position (including the vicinity of the focus), the light emitted from the light emitting source 2 can be made incident (introduced) into the optical fiber 5, and the introduced light Is guided through the optical fiber and can illuminate a desired portion from the exit end face. The reflecting mirror 7 can easily be made to have specularity by plating or metal deposition.

In the present invention, in order to reuse the light applied to the area around the incident end surface 5a of the optical fiber 5, the reflecting mirror 7 is provided in the area around the incident end surface 5a of the optical fiber 5. That is, as shown in FIG. 2, the reflected light r reflected by the reflecting mirror 7 passes through the Fresnel lens 3 and the diffuse reflection surface 8
Reach Then, it is diffusely reflected from the diffuse reflection surface 8 in many directions. A part of the diffused reflected light q (diffuse reflected light parallel to the axis C) passes through the Fresnel lens 3 and enters the incident end surface 5a of the optical fiber 5, and is introduced into the optical fiber 5.

The light guide light source device 10 is used as a light source of an illuminating device which takes out light from the exit end of the optical fiber 5 and irradiates a desired portion through other optical parts such as a lens as necessary. In addition, it can be used as a light source for various devices using an optical fiber. For example, the optical fiber itself may be used for a device that uses it as decorative illumination (so-called electric decoration).

For general illumination, an LED 22 that emits white light may be used. However, by utilizing the characteristic of the LED that has various kinds of light emission, visible light such as red, green, blue, or red light, or red light is used. An LED that emits light having a wavelength such as external light or ultraviolet light may be used. Also, by combining LEDs of a plurality of colors, it is possible to illuminate various colors.

Furthermore, the above-mentioned embodiments are merely examples of the present invention, and it is obvious that appropriate modifications and changes made within the scope of the present invention are also included in the scope of the claims of the present application. . Specifically, the materials forming each optical component and other members are not limited to those described above. Further, the shape and arrangement of each optical component can be appropriately changed within the range of conditions satisfying the gist of the present invention.

[0029]

As described above, according to the light guide light source device of the present invention, the light emitted from the light emitting diode as the light emitting source can be guided to the incident end face of the optical fiber.
Light that does not enter the incident end face of the optical fiber is reflected by the reflecting mirror toward the light emitting source, and the diffused reflecting surface provided in the non-light emitting area of the light emitting source diffuses and reflects the reflected light and re-reflects the diffuse reflected light. Since the light is introduced into the fiber, the light from the light emitting source can be efficiently taken into the optical fiber. Therefore, the incident efficiency on the incident end surface of the optical fiber is significantly improved as compared with the conventional case.

Therefore, if the light guide light source device of the present invention is applied to a lighting device, for example, a high illuminance can be obtained on the exit end face side of the optical fiber. Further, since the light is efficiently used on the way to the incidence on the optical fiber, less electric power is required to be supplied to the light emitting source in order to obtain the same illuminance. Further, since the heat generated by the light emitting source is also reduced by that amount, the cooling means is not required or becomes simpler. Furthermore, it is also advantageous for downsizing the device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a light source device for a light guide according to an embodiment of the present invention, in which only light incident on an optical axis of an incident end face of an optical fiber is described.

FIG. 2 is an optical path configuration diagram showing how the light irradiating the region around the incident end face of the optical fiber is incident on the incident end face of the optical fiber by reflection and diffuse reflection in the light guide light source device of FIG. .

FIG. 3 is a plan view of a light emitting source used in the light guide light source device of FIG. 1 as viewed from an incident end face side on an optical fiber side.

[Explanation of symbols]

1 body 2 light source 21 board 22 Light emitting diode (LED) 23 Collimating lens 24 Lens holder 3 Fresnel lens (condensing lens) 4 lid plate 5 optical fiber 5a Incident end face 7 Reflector 8 Diffuse reflection surface 10 Light source device r reflected light q Diffuse reflected light

Claims (4)

[Claims] 1. A light source device for sending light from an incident end face of an optical fiber to the inside thereof, wherein a light emitting source and a condenser for condensing light from the light emitting source toward the incident end face of the optical fiber. A lens, a reflecting mirror provided in a region around the incident end face of the optical fiber and reflecting light not incident on the incident end face of the optical fiber toward the light emitting source, and the reflection mirror formed in the non-light emitting region of the light emitting source. A light guide light source device comprising: a diffuse reflection surface that diffusely reflects light reflected from a mirror. 2. The light guide according to claim 1, wherein the light emitting source includes a pair of a plurality of light emitting diodes and a collimating lens provided in front of each of the light emitting diodes. Light source device. 3. The light guide according to claim 2, wherein the diffuse reflection surface is formed on a surface of the lens holding plate that supports the collimator lens, the surface facing the incident end surface of the optical fiber. Light source device. 4. The light source device for a light guide according to claim 1, wherein the condenser lens is a Fresnel lens.