JP2007042938A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a secondary lens 5 and a reflector 7 used for a surface-mounting light-emitting diode 3 to reveal side emitter light distribution properties are not realized yet, a shell-shaped light-emitting diode is not sufficiently high in heat dissipating properties and is not capable of structurally realizing high-output side emission light distribution properties, a configuration which is not a secondary lens 5 but a primary lens having side emitter light distribution properties can be found, but the configuration concerned is hard to manufacture and is not capable of displaying ideal side emitter light distribution properties. <P>SOLUTION: An optical device is equipped with a surface-mounting light-emitting diode 3 with a light-emitting diode chip 1, a lens 5 which condenses light in the height-wise direction of a mounting plane covering the peripheral part of the light-emitting diode 3, and a mirror reflector 7 which makes the light emitted from the light-emitting chip 1 reflect in the direction of a mounting plane covering the upper part of the light-emitting diode 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical device, and more particularly to an optical device configured using a light emitting diode. The present invention also relates to an optical device used for a backlight light source of a liquid crystal display element used for image display such as channel letters, computers, word processors, and televisions, and in particular, has a high balance between high luminance, uniform light emission and high color mixing. It relates to the optical device taken.

  Furthermore, it is possible to uniformly irradiate a displayed product used in a show window or a display case and display the product without generating bright lines or bright spots.

  Furthermore, the optical device can be used for illumination for decorating Christmas trees and the like. The present invention also relates to an optical device that can be diverted to an illuminating device such as an aviation obstacle light or wall illumination.

  In recent years, liquid crystal display devices having a backlight light source have begun to be used in portable electronic devices and various image display devices. The liquid crystal display device includes a light guide plate, a liquid crystal cell, a prism sheet, a diffusion sheet, a backlight, and the like. Currently, display devices using liquid crystal display devices are becoming larger, and with the increase in size, light guide plates, which are essential components for liquid crystal display devices, are difficult to manufacture. A light guide plate-less liquid crystal display device that does not have a light guide plate has been developed for weight reduction and thickness reduction.

  Conventionally, linear light sources such as FL (fluorescent lamps) have been used as the core light source that forms the planar light source, but light emitting diodes that are rapidly increasing in brightness considering low power consumption and long life 3 is starting to be used as the light source of the backlight.

  Furthermore, replacement of surface light emitting diodes 3 with light sources such as FL (fluorescent lamps) has started in display refrigerators that display drinking water and the like installed at convenience stores and the like.

  Furthermore, the surface-mounted light emitting diode 3 for illumination that decorates the Christmas tree is required to diverge the emitted light instead of condensing it.

  When these optical devices have an optical characteristic in which the mounting surface of the surface-mounted light-emitting diode 3 is the xy plane, the z-axis is defined as the side perpendicular to the xy plane and facing the mounting surface of the surface-mounted light-emitting diode 3. The axis is positioned at the center of the surface mount light emitting diode 3. In this case, the light distribution characteristic is bilaterally symmetrical and has two peaks. The light distribution characteristic has a peak of emission intensity at a portion that is not the center as defined above, and emits light in a substantially bilaterally symmetric form instead of tilting left or right. Refers to luminescent properties. Such a light emission characteristic is called a batwing light distribution characteristic (FIG. 5) and a side emitter light distribution characteristic (FIG. 4).

  On the other hand, the light distribution characteristic with respect to the xy direction is a light distribution characteristic having a curve of cos θ, which means that light is emitted in a circular plane shape, and the position facing the light source emits the strongest light, and the position facing the center is the center. In this case, the light is attenuated as it deviates from the center, and the light cannot be detected at a position deviated by 90 ° from the center, which is similar to the curve of cos θ. The light emitting diode 3 and the like not particularly attached with the lens 5 or the like have such light distribution characteristics. Such a light distribution characteristic is also referred to as a Lambertian light distribution characteristic (FIG. 6). Light like a miniature bulb is completely omnidirectional, and it can be considered that a spherical object is shining over and over.

  Here, the above-mentioned optical instrument is most preferred as a side emitter light distribution characteristic as an optical characteristic. The side emitter light distribution characteristic is directly used for the refrigeration light source. In addition, other optical devices eventually emit light in the z-axis direction, which is the mounting surface, but a reflector 7 is formed around the surface-mounted light emitting diode 3, and this reflector 7 has optical characteristics. Since the light is adjusted, there is a technique in which light is not emitted directly in the z-axis direction but is once spread in the xy plane direction and optically adjusted by the reflector 7 and then emitted in the z-axis direction.

Japanese Utility Model Publication No. 7-3154 JP 2004-281606 A

  The secondary lens 5 and the reflector 7 that are used for the surface-mounted light-emitting diode 3 and exhibit the side-emitter light distribution characteristics have not been realized so far. Since the shell-type light emitting diode is not preferable in terms of heat dissipation, a high-output side emitter light distribution characteristic cannot be realized due to its structure. Further, there is a structure having a side emitter light distribution characteristic of the primary lens 5 instead of the secondary lens 5, but it is difficult to manufacture and an ideal side emitter light distribution characteristic is not obtained. The reason is that since the light emitting diode chip is not a point light source, it is impossible to perform total reflection using the difference in refractive index unless a mirror such as a mirror is provided, and light that cannot be controlled directly above the light emitting diode chip. Leaks. Further, when the primary lens is used, naturally, the lens 5 and the reflector 7 are integrated with each other, and therefore, when the mirror of the mirror is formed on the reflector 7, the mechanical damage to the mirror cannot be ignored.

  In order to solve the above-described problems, an optical device according to the present invention mounts a surface-mounted light-emitting diode 3 having a light-emitting diode chip 1 and an outer peripheral portion of the light-emitting diode 3 and incident light from the light-emitting diode. Covering the upper part of the light-emitting diode 3 with the lens 5 that converts the light into substantially parallel light with respect to the surface, and the surface covered with a mirror that converts the light from the light-emitting diode 3 into light substantially parallel with the mounting surface It has a reflector 7 and a cylindrical translucent member, and the lens and the reflector are fitted via the translucent member.

  Since the surface-mounted light emitting diode 3 is employed, high heat dissipation can be ensured. By having a reflector 7 that covers the upper part of the surface-mounted light-emitting diode 3 and reflects the light from the light-emitting diode chip 1 in the direction of the mounting surface, and with a reflector 7 whose surface is covered, only total reflection utilizing the refractive index difference is achieved. In addition, the light that has not been totally reflected can contribute to the side emitter light distribution characteristics by the mirror effect of the mirror.

  In the optical device according to the present invention, the light emitting diode 3 and the lens 5 are provided with an air layer 9 interposed therebetween. The structure in which the air layer 9 is interposed, that is, the surface-mounted light emitting diode 3 that is physically a heat source and the lens 5 are arranged without being in contact with each other, so that damage to the lens 5 due to heat can be avoided. Further, in the case of the sealed lens 5, the lens 5 effect can be exhibited only by one of the outer surfaces, but by adopting the hollow 13 structure, not only the outer surface of the lens 5 but also The inner surface can also exhibit the lens 5 effect, and the lens 5 effect can be improved.

  The reflector 7 according to the present invention is configured with a resin as a base material, and a mirror is formed on the light emitting diode 3 side. By adopting this configuration, it is possible to prevent external damage to the mirror. Therefore, it can be formed thinner than the case where the mirror is formed outside.

  The light emitting diode 3 according to the present invention has a light distribution characteristic with an optical characteristic of approximately cos θ. This is because the optical characteristics of the light-emitting diode show a light distribution characteristic of approximately cos θ in principle without using a special lens or the like, and the purpose of the present invention is to use this light distribution characteristic by changing it.

  Fresnel processing is performed in the direction in which the cylindrical light-transmitting member according to the present invention collects light in the cylinder height direction. It is possible to enhance the light emission to the side by causing the lens 5 effect to be exerted also on the cylindrical translucent member.

  The periphery of the light-emitting diode chip 1 forming the light-emitting diode 3 according to the present invention is a hollow 13. By forming a hollow 13 structure around the light-emitting diode chip 1, the lens 5 effect inside the surface-mounted light-emitting diode 3 can be suppressed, and an ideal point light source can be realized. Since the light source is assumed to be a point in the design, the difference between the experimental value and the design value can be minimized by using the light source as a point light source.

  The light emitting diode 3 according to the present invention is mounted on a heat sink 15. By mounting the surface mount type light emitting diode 3 on the heat sink 15, it can be applied to a high output surface mount type light emitting diode.

  With the above configuration, according to the above-described optical device according to the present invention, it is possible to use the light distribution characteristic of a surface-mounted light emitting diode that is generally distributed by converting it into a side emitter light distribution characteristic.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the optical apparatus for embodying the technical idea of the present invention, and the present invention does not limit the optical apparatus to the following. Further, the size and positional relationship of the members shown in the drawings are exaggerated for clarity of explanation.

  Embodiments according to the present invention will be described below with reference to the drawings.

  The optical device of the present embodiment is provided in a configuration as shown in FIG. FIG. 2 is a sectional view taken along line I-I ′ in FIG. 1. 1 shows a schematic diagram of the internal structure. FIG. 3 shows a development view of FIG.

  Each member will be described individually below.

(Surface mount light emitting diode 3)
The surface-mounted light emitting diode 3 refers to the one on which the light emitting diode chip 1 is mounted.

  The light-emitting diode chip 1 is formed by forming a semiconductor such as GaAlN, ZnO, ZnS, ZnSe, SiC, GaP, GaAlAs, AlN, InN, AlInGaP, InGaN, GaN, or AlInGaN on a substrate as a light-emitting layer. Examples of the semiconductor structure include a homo structure having a MIS junction, a PIN junction, and a PN junction, a hetero structure, and a double hetero structure. Various emission wavelengths can be selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the degree of mixed crystal. The light emitting layer may have a single quantum well structure or a multiple quantum well structure which is a thin film in which a quantum effect is generated.

  It is preferable to use a gallium nitride-based compound semiconductor as a semiconductor material capable of forming the high-intensity light-emitting diode chip 1, and in red, a gallium / aluminum / arsenic semiconductor or an aluminum / indium / gallium / phosphorus semiconductor is used. However, it can be used in various ways depending on the application. The light emission color is appropriately selected as described above, and when used in an automobile or the like, the company color of the automobile company is often selected.

  When a gallium nitride compound semiconductor is used, a material such as sapphire, spinel, SiC, Si, ZnO or GaN single crystal is used for the semiconductor substrate. In order to form gallium nitride with good crystallinity with high productivity, it is preferable to use a sapphire substrate. An example of a light emitting diode chip using a nitride compound semiconductor is shown. A buffer layer such as GaN or AlN is formed on the sapphire substrate. A first contact layer made of N-type or P-type GaN, an active layer made of an InGaN thin film having a quantum effect, a clad layer made of P or N-type AlGaN, and a second layer made of P or N-type GaN. The contact layers can be formed in order. Gallium nitride-based compound semiconductors exhibit N-type conductivity without being doped with impurities. When forming a desired N-type gallium nitride semiconductor such as improving luminous efficiency, Si, Ge, Se, Te, C, etc. are preferably introduced as appropriate as N-type dopants.

  On the other hand, when a P-type gallium nitride semiconductor is formed, a P-type dopant such as Zn, Mg, Be, Ca, Sr, or Ba is doped. Since a gallium nitride based semiconductor is difficult to be converted to P-type only by doping with a P-type dopant, it is necessary to make it P-type by annealing it by heating in a furnace, low electron beam irradiation, plasma irradiation or the like after introducing the P-type dopant. The semiconductor wafer thus formed is partially etched to form positive and negative electrodes. Thereafter, the light emitting diode chip 1 can be formed by cutting the semiconductor wafer into a desired size.

  A plurality of such light-emitting diode chips 1 can be used as appropriate, and the color mixing property in white display can be improved by combining them. For example, one light emitting diode chip 1 capable of emitting green light and one light emitting diode chip 1 capable of emitting blue and red light can be provided. When the surface-mounted light emitting diode 3 emits white mixed color light using a fluorescent material, the complementary color relationship with the emission wavelength from the fluorescent material and the deterioration of the translucent resin are taken into consideration. The emission wavelength is preferably 400 nm or more and 530 nm or less, and more preferably 420 nm or more and 490 nm or less. In order to further improve excitation and light emission efficiency of the light emitting diode chip 1 and the fluorescent material, 450 nm or more and 475 nm or less are more preferable. The light-emitting diode chip 1 having a main light emission wavelength in the ultraviolet region shorter than 400 nm or the short wavelength region of visible light can be used in combination with a member that is relatively difficult to deteriorate by ultraviolet rays.

(Lens 5)
The material of the lens 5 may be any material that has a certain level of translucency with respect to light having a wavelength between near ultraviolet, visible light, and near infrared. Specifically, acrylic resin, polycarbonate Resin, amorphous polyolefin resin, polystyrene resin, norbornene resin, cycloolefin polymer (COP), epoxy resin, silicone resin, acrylonitrile butadiene styrene resin (ABS resin), sapphire, quartz, soda glass, borosilicate glass , Silica glass, oxynitride glass, rare earth glass and the like. A refractive index of 1.3 to 2.0 is preferably used.

(Reflector 7)
For the mirror of the reflector 7, a metal such as Ag, Al, Ni, Au, or Cu, or a metal oxide film layer such as SiO2 / ZrO2 or SiO2 / TiO2 is used. When the emitted light from the surface-mounted light emitting diode 3 is a mixed color light consisting of a plurality of wavelength bands, a metal whose reflection does not depend on the wavelength is preferably used, and in the case of a metal, Ag having a high reflectivity or durability is used. High Al is preferably used. When the light emitted from the surface-mounted light emitting diode 3 is monochromatic light, a metal oxide film layer having a higher reflectance than that of a metal is used. The metal oxide film layer has wavelength dependency, and the film thickness is optimized depending on the wavelength. Conversely, when the emitted light is a mixed color light having a plurality of wavelength bands, it may be possible to improve the illumination property by using a metal oxide film layer and spectrally divide it.

(Cylindrical transparent member)
The cylindrical material is selected from the same group as the material of the lens 5, and may be the same as or different from the lens 5 material. Specifically, acrylic resin, polycarbonate resin, amorphous polyolefin resin, polystyrene resin, norbornene resin, cycloolefin polymer (COP), epoxy resin, silicone resin, acrylonitrile / butadiene / styrene resin (ABS resin), sapphire , Quartz, soda glass, borosilicate glass, silica glass, oxynitride glass, rare earth glass, and the like. A refractive index of 1.3 to 2.0 is preferably used.
In the optical device according to the present invention, the lens 5 and the reflector 7 are mechanically joined via a cylindrical translucent member. Although the reflector 7 and the lens 5 are separate parts, it is preferable that the reflector 7 and the lens 5 are mechanically coupled to each other because they are inseparable from each other in order to express one optical characteristic together. Although it is conceivable that the metal rod is partially fixed with a simple metal rod or the like, the shadow of the metal rod or the like itself is formed, which is not preferable for the side emitter light distribution characteristics. Although fixing with a rod such as a translucent resin is also conceivable, it is inevitable that refraction or reflection occurs at the interface between the resin and air, and an adverse effect on the side emitter light distribution characteristics is naturally assumed. Therefore, by using a cylindrical translucent member, it can be realized without adversely affecting the side emitter light distribution characteristics. Further, by applying an optical design to the cylindrical light-transmitting member, it is possible to give an arbitrary optical characteristic while the light distribution characteristic of the base is the side emitter light distribution characteristic. For example, the translucent member can be a colored translucent member, and if a plurality of colored translucent members are arranged in a line on the z-axis, different colors are emitted depending on the viewing position and angle. Can be used as illumination. Furthermore, if it is designed to be rotatable, the illumination property is further enhanced.

In addition, when used as illumination, glare which is disliked by ordinary optical devices, that is, strong non-uniform light emission in the xy plane may be preferred. In such a case, if the phosphor is formed in a pattern on the translucent member, the emission color is changed only in the portion of the pattern and the illumination property is improved. Further, since it is physically separated from the light source as a heat source, not only an inorganic phosphor having good heat resistance but also an organic phosphor having poor heat resistance can be used.
Furthermore, by encapsulating a metal ball or a metal plate (lame) in the translucent member, irregular reflection is caused on the metal surface, and further illumination properties are improved. Partially use translucent members with different refractive indices, partially change translucent member thickness, include voids, or treat surfaces like gem cuts, Fresnel lenses, and waribo lenses The illumination property is dramatically improved by applying.

(Phosphor)
As the phosphor usable in the optical apparatus according to the present invention, as an inorganic phosphor having high heat resistance, an aluminum oxide phosphor, a lutetium / aluminum / garnet phosphor, a nitride phosphor, an alkaline earth metal Silicate phosphors or the like can be used, or organic phosphors having high conversion efficiency can be used. For example, when encapsulating in a surface-mounted light emitting diode 3, an inorganic phosphor with high heat resistance is preferably used, and when encapsulated in a cylindrical transparent member, heat is not so much heat resistance. An organic phosphor having a low but high conversion efficiency is preferably used.

  INDUSTRIAL APPLICABILITY The present invention can be used for a liquid crystal backlight, a backlight for a mere signboard, etc., which is remarkably required to be thin and light, a refrigerator for a display, general illumination, and an illumination light source.

1 is a perspective view of an optical device according to an embodiment of the present invention. It is a section perspective view of an optical device of an embodiment concerning the present invention. 1 is an exploded perspective view of an optical device according to an embodiment of the present invention. It is a figure showing the side emitter light distribution characteristic. It is a figure showing a batwing light distribution characteristic. It is a figure showing a Lumbershan light distribution characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light emitting diode chip 3 ... Surface mount type light emitting diode 5 ... Lens 7 ... Reflector 9 ... Air layer 11 ... Cylindrical transparent member 13 ... Hollow 15 ... heatsink

Claims (6)

A surface-mounted light-emitting diode having a light-emitting diode chip, a lens that covers an outer peripheral portion of the light-emitting diode, converts light incident from the light-emitting diode into light substantially parallel to the mounting surface, and an upper portion of the light-emitting diode. A reflector having a surface covered with a mirror that covers and converts light from the light emitting diode into substantially parallel light with respect to a mounting surface; and a cylindrical translucent member. An optical device that is fitted through a light member. 2. The optical device according to claim 1, wherein the light emitting diode and the lens are provided with an air layer interposed therebetween. The optical device according to any one of claims 1 to 3, wherein the reflector is configured with a resin as a base material, and a mirror is formed on the light emitting diode side. The optical device according to claim 1, wherein an optical characteristic of the light emitting diode has a light distribution characteristic of approximately cos θ. The optical device according to claim 1, wherein a periphery of a light emitting diode chip forming the light emitting diode is hollow. The optical device according to claim 1, wherein the light emitting diode is mounted on a heat sink.

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