JP2006261375A - Led light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED light source device which generates a high-intensity linear light. <P>SOLUTION: The LED light source device comprises a substrate; two or more LED elements; and a reflector arranged on the substrate, so as to surround the two or more LED elements collectively. Two or more LED elements are arranged on the substrate. Each LED element has a p-electrode and an n-electrode in one surface side. Any one of electrodes is formed in an etched and arranged so that the electrode may exist between the LED elements adjacent to the electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an LED light source device. In detail, it is related with improvement of the reflector of an LED light source device.

  A linear light source device is generally used as a light source device for a backlight such as a liquid crystal panel. As the linear light source device, there is a light source unit in which LED elements are linearly arranged. In the LED light source device, in order to improve the light extraction efficiency, a reflector is installed around the LED element.

Currently, there is a demand for realizing a higher-brightness linear LED light source device. For increasing the brightness, it is effective to mount the LED elements at a high density. However, when the LED elements are mounted at a high density, the interval (pitch) between the LED elements is narrowed, so that it is difficult to install a reflector for each LED so that preferable light distribution characteristics can be obtained. That is, in order to increase the light extraction efficiency of each LED element, it is preferable to provide a reflector for each LED element, but it is difficult to adopt such a configuration when performing high-density mounting.
On the other hand, for linear LED light source devices, reduction of luminance unevenness is also required. That is, the problem is to convert the light of the LED element, which is originally a point light source, into more uniform linear light.
In addition, installing a large number of LED elements at a high density increases the amount of heat generation, which may reduce the drive stability and reliability of the LED elements.
In view of the above problems, an object of the present invention is to provide an LED light source device that generates high-luminance linear light. Another object of the present invention is to provide an LED light source device that generates more uniform linear light. Another object is to provide an LED light source device that is excellent in heat dissipation.

In order to achieve at least one of the above objects, the present invention provides the following LED light source device. That is,
A substrate,
A plurality of LED elements arranged on the substrate, wherein the LED element has a p-electrode and an n-electrode on one side, and one of the electrodes is formed in an etched portion, and the one electrode is an electrode A plurality of LED elements arranged so as to exist between adjacent LED elements;
A reflector disposed on the substrate so as to collectively surround the plurality of LED elements;
It is an LED light source device provided with.

  In the present invention, the reflector is not provided for each LED element, but is provided so as to collectively surround a plurality of LED elements. Thereby, the space | interval (pitch) of an LED element can be made small. That is, the LED elements can be arranged with high density, and high luminance is achieved. Furthermore, since the reflector reflects light emitted from the LED element in the lateral direction upward, the light extraction efficiency is improved. That is, high brightness by high-density mounting of LED elements and improvement of light extraction efficiency by the reflector are compatible, and higher brightness is realized. Here, for example, a GaN-based LED element on a sapphire substrate, which has a pn electrode on one side and is disposed in the periphery of the LED element, has a characteristic that the amount of light emitted from the n-electrode side in the lateral direction is small due to the structure. Have Therefore, by arranging the LED elements such that the n-electrodes of such LED elements exist between adjacent LED elements, more of the light emitted from the LED elements in the lateral direction is directed toward the reflector. proceed. As a result, the light extraction efficiency is further improved.

  The lighting device in the present invention includes a substrate, an LED element, and a reflector. The kind of board | substrate to be used is not specifically limited, A well-known thing can be employ | adopted. For example, a ceramic substrate made of aluminum, aluminum alloy, copper, copper alloy, aluminum nitride, or the like can be used. These substrates have a high thermal conductivity and can improve the heat dissipation of the LED element.

In the present invention, for example, a GaN-based LED element formed on sapphire having a pn electrode on one side is used as the LED element. It is preferable that the GaN-based LED element electrode face be down and flip-chip mounted on the substrate via a gold bump. This is because it can be directly mounted on the substrate, so that there is no need for wire bonding, and the LED elements can be arranged with higher density.
In the present invention, a plurality of LED elements are used, and these are arranged on the substrate in a substantially linear shape. The space | interval (pitch) of an LED element is 0.4-2.0 mm, for example, Preferably it is 0.5 mm to 1.5 mm. By reducing the pitch in this way, the brightness can be increased. In addition, luminance unevenness can be reduced, and more uniform linear light can be generated. As used herein, “substantially linear” refers to a state in which LED elements are linearly arranged in one or more rows. In the present invention, all the LED elements are typically arranged in a straight line, but may be arranged in a curved line.

  Here, in an LED element having a pn electrode on one side, the amount of light emitted in the lateral direction from the n electrode side formed in the etched portion is small. Therefore, in the present invention, the plurality of LED elements are arranged such that the electrodes formed on the etched portions of the LED elements are on a virtual axis passing through the center of each LED element. With this arrangement, more of the light traveling in the lateral direction from each LED element travels in the direction of the reflector described later. Since the reflector receives the light in the lateral direction of the LED element and reflects it upward, the light extraction efficiency is improved.

  In the present invention, a reflector that collectively surrounds a plurality of LED elements arranged in a substantially linear shape is used. That is, instead of providing a reflector for each LED element, one reflector is used for a plurality of LED elements. The material of the reflector is not particularly limited as long as it is a material that can reflect the light of the LED element, such as a metal such as aluminum or a white resin. Among these, it is preferable to form the material with high thermal conductivity such as metal such as aluminum. This is because the heat dissipation characteristics of the LED light source device are improved. In addition, after shaping | molding a material with low light reflectivity or a non-light-reflective material, you may make into a reflector the thing which gave the light reflectivity by giving a plating process or white coating to the area | region used as a light-receiving surface.

  Hereinafter, the present invention will be described in more detail with reference to examples.

FIG. 1 is a perspective view of an LED light source device 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the structure of the GaN-based LED element 2a. FIG. 3 is a top view of the LED light source device 1. 4 is a longitudinal sectional view taken along line AA in FIG.
The LED light source device 1 includes six GaN-based LED elements 2 a to 2 f having the same structure, a reflector 4, and a substrate 3. As shown in FIG. 2, the GaN-based LED element 2a includes a buffer layer 23a, an n-type GaN-based semiconductor layer 24a, a layer 25a including a light-emitting layer made of a GaN-based semiconductor, and p on an insulating sapphire substrate 22a. The n-type GaN-based semiconductor layer 26a is sequentially stacked, and a part of the n-type GaN-based semiconductor layer 24a is exposed by etching to form an n-electrode 21a on the n-type GaN-based semiconductor layer 24a. In this structure, a p-electrode 27a is formed on the layer 26a. That is, as shown in FIG. 2, the p electrode 27a and the n electrode 21a are formed on the same surface side. Further, since the n-electrode 21a is formed in the lateral direction of the layer 25a including the light-emitting layer, the n-electrode 21a prevents a part of light emitted from the layer 25a including the light-emitting layer from traveling. As a result, the GaN-based LED element 2a emits less light in the lateral direction from the n-electrode 21a side. The GaN-based LED element 2a is flip-chip mounted on the substrate 3 via gold bumps so that the p-electrode 27a and the n-electrode 21a are on the lower surface side (substrate 3 side). Similarly, the GaN-based LED elements 2b to 2f are flip-chip mounted on the substrate 3. Six GaN-based LED elements 2a to 2f are linearly arranged on the substrate 3 at intervals (pitch) of 0.1 mm. As shown in FIG. 3, the GaN-based LED elements 2a to 2f are arranged such that the respective n electrodes 21a to 21f are located on a virtual axis 20 that connects the centers of the GaN-based LED elements 2a to 2f.

The reflector 4 is made of aluminum and is installed on the substrate 3 so as to collectively surround the six GaN-based LED elements 2a to 2f. As shown in FIG. 3, the reflector 4 is divided into six sections a to f in the longitudinal direction. The size of each section af is substantially the same, and one GaN-based LED element 2a-f is arranged in each section af. In each section, the surfaces (reflective surfaces) 41a-f facing the GaN-based LED elements 2a-f of the reflector 4 are located on the imaginary axis 20 from the central part toward the end part (part continuous to the adjacent section). Curved to approach. More specifically, in the section a, the upper end (upper edge) 42a of the reflecting surface 41a is along a virtual circle centered on the GaN-based LED element 2a. Further, as shown in FIG. 3, the reflection surface 41a is inclined at a predetermined angle from the upper end 42a toward the lower end (edge on the substrate side) 43a so as to approach the GaN-based LED element 2a. That is, the cross section of the reflecting surface 41a in the direction perpendicular to the optical axis 5 is along a virtual circle centered on the GaN-based LED element 2a. The end of the reflection surface 41a is connected to the end of the reflection surface 41b of the adjacent section b. Similarly, for the sections b to f, the reflecting surfaces 41b to f have upper ends 42a to f along virtual circles centered on the GaN-based LED elements 2b to f, and GaN-based toward the lower ends 43a to f. It inclines so that it may approach LED element 2b-f. Furthermore, the end portions of the reflection surfaces 41b to f are connected to the end portions of the adjacent sections. Therefore, a region surrounded by the reflector 4 (a region in the vicinity of the GaN-based LED elements 2a to 2f) communicates between all the sections.
The inclination angles of the reflecting surfaces 41a to f are determined in consideration of the directivity angles of the GaN-based LED elements 2a to 2f so that preferable light distribution characteristics can be obtained.

  Next, the light emission mode of the LED light source device 1 will be described. A part of the light from the GaN-based LED elements 2a to 2f is emitted in the optical axis direction of the GaN-based LED elements 2a to 2f, and the other part is emitted from the GaN-based LED elements 2a to 2f in the lateral direction. At this time, since the n-electrodes 21a to 21f of the GaN-based LED elements 2a to 2f are located on the virtual axis 20, more light of the lateral light travels toward the reflector 4 side. The reflecting surfaces 41a to f of the reflector 4 reflect the received light in the optical axis direction of the GaN-based LED elements 2a to 2f.

  In such an LED light source device 1, the GaN-based LED elements 2a to 2f are flip-chip mounted on the substrate 3 and arranged at a narrow pitch (0.1 mm). Thereby, since GaN-type LED element 2a-f is installed in high density, high brightness is achieved. Furthermore, since most of the light in the lateral direction of the GaN-based LED elements 2a to 2f travels toward the reflector 4 and is reflected in the optical axis direction by the reflecting surfaces 41a to 41f, the light extraction efficiency is improved. Further, the reflection surfaces 41a to 41f approach the virtual axis 20 at the end of each section. That is, since each end of the reflective surfaces 41a to f is close to the GaN-based LED elements 2a to 2f, the optical path to the reflective surfaces 41a to 41f is shortened at the end of each section, and light loss is reduced. Further, the cross sections (transverse sections) of the reflection surfaces 41a to 41f in the direction perpendicular to the optical axis 5 are along virtual circles centering on the GaN-based LED elements 2a to 2f. Accordingly, the reflecting surfaces 41a to 41f receive light from the GaN-based LED elements 2a to 2f at a substantially constant light receiving angle and reflect them substantially uniformly in the direction of the optical axis in the cross section. Is obtained. As a result, luminance unevenness is reduced, and more uniform linear light can be generated. Moreover, since the reflector 4 is made of aluminum, the heat dissipation characteristics are high. Since the reflector 4 is located at a position close to the GaN-based LED elements 2a to 2f in each section, the heat dissipation of the GaN-based LED elements 2a to 2f can be enhanced.

In the LED light source device 1, the reflecting surfaces 41 a to 41 f of the reflector 4 have curved surfaces along a circle centering on the GaN-based LED elements 2 a to f as shown in FIG. 3, but the reflector shown in FIG. 40, only the vicinity of the end portions of the reflection surfaces 410a to 410f may have a shape protruding toward the virtual axis 20 side. A similar effect can be obtained by the reflector 40. Further, the reflecting surfaces 41a to 41f are surfaces inclined at a predetermined angle from the upper ends 42a to f toward the lower ends 43a to f, but may be curved surfaces as long as preferable light distribution characteristics are obtained. good.
In the LED light source device 1, six GaN-based LED elements 21 a to 21 f are used and collectively surrounded by the reflector 4, but more LED elements such as 10 or 20 are used and these are collectively reflected by the reflector. It is also possible to go around. Since the amount of heat generation increases as the number of LED elements used increases, it is preferable to use a reflector formed of a material having high thermal conductivity. This is because the reflector having high thermal conductivity is close to the LED element at the end of each section, so that the heat dissipation characteristics are improved and the driving stability of the LED element can be secured.

  The present invention is not limited to the above-described embodiments and examples. Various modifications are also included in the present invention as long as those skilled in the art can easily correspond without departing from the scope of the claims.

  The LED light source device of the present invention can be used as a light source for backlight illumination of liquid crystal panels such as mobile phones, PCs, and liquid crystal televisions, and for information transmission media such as indicator boards and advertisements used outdoors or indoors. Figured.

FIG. 1 is a perspective view of an LED light source device 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the structure of the GaN-based LED element 2a. FIG. 3 is a top view of the LED light source device 1. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 shows a top view of an LED light source device according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 LED light source device 2a-f GaN-type LED element 20 Virtual axis 3 Substrate 4 40 Reflectors 41a-f 410a-f Reflecting surface 5 Optical axis

Claims (5)

A substrate,
A plurality of LED elements arranged on the substrate, the LED elements having a p-electrode and an n-electrode on one surface side, one electrode of which is formed in a etched portion, and the one electrode is A plurality of LED elements arranged to exist between the adjacent LED elements;
A reflector disposed on the substrate so as to collectively surround the plurality of LED elements;
An LED light source device.   The LED light source device according to claim 1, wherein the LED element is a GaN-based LED element provided on an insulating material.   3. The LED light source device according to claim 1, wherein the one electrode of the plurality of LED elements arranged on the substrate is located on a virtual axis that connects centers of the plurality of LED elements. .   The LED according to claim 3, wherein the reflector includes a plurality of sections in which the LED elements are arranged one by one in each section, and an end portion of each section protrudes toward the virtual axis side. Light source device.   The LED light source device according to claim 4, wherein each of the sections of the reflector has a continuous curved surface that approaches the virtual axis from the center toward the end.

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