JP2004172507A - Reflective light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflective light emitting device which takes out outgoing light with high control efficiency from a light emitting element having a plurality of light emitting parts in a radiating direction by a reflection surface arranged oppositely to the light emitting element. <P>SOLUTION: In the reflection type light emitting device for reflecting light from the light emitting element to the radiating direction by the light emitting element and the reflection surface formed so as to be faced to the light emitting element, the light emitting element has a plurality of light emitting parts, and the reflection surface is formed by a plurality of parabolic surfaces focused on respective light emitting parts. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a reflection type light emitting device used as a spot light source such as an optical fiber, a projector, a printer, a headlight and a rear light of a car, and a leading light in a machine.
[0002]
[Prior art]
The reflection type light emitting device has a light emitting element 12 and a reflection surface (reflector) 11 provided to face a light emitting surface of the light emitting element 12. The reflecting surface 11 is a paraboloid whose focal point is the center of the light emitting surface of the light emitting element 12.
With such a configuration, light emitted from the light emitting element 12 can be reflected by the reflecting surface 11 facing the light emitting surface of the light emitting element 12 and emitted in the front direction. As described above, by once irradiating the light from the light emitting element 12 to the reflecting surface and using the reflected light, it is possible to reduce the luminance unevenness as compared with the case of using the direct light from the light source. Since almost the entire luminous flux of light emitted from the light emitting element can be emitted in the front direction as parallel light, it is used as a light source having high light-collecting characteristics.
[0003]
[Patent Document 1]
JP-A-1-205480
[0004]
[Problems to be solved by the invention]
However, as shown in FIG. 3, the light emitting element 12 actually has a plurality of light emitting units instead of emitting light from one point. Therefore, it is difficult to control the radiation direction of light.
Therefore, the present invention provides a reflective light emitting device that can efficiently emit light in a desired direction by forming a reflective surface shape according to the light distribution characteristics of light from a light emitting element having a plurality of light emitting units. The purpose is to do.
[0005]
[Means to solve the problem]
In order to solve the above-mentioned problem, a reflection type light emitting device according to claim 1 of the present invention reflects light from the light emitting element in a radiation direction by a light emitting element and a reflecting surface provided to face the light emitting element. A reflection type light emitting device, wherein the light emitting element has a plurality of light emitting portions, and the reflecting surface is formed by a plurality of paraboloids having the light emitting portions as focal points.
[0006]
With such a configuration, the light emission of the element can be used more effectively than the reflection surface having only the focus at the center of the light emitting element (center of the light emitting surface). improves. For example, in the case where a light emitting portion is provided on the side end surface, by providing a surface having the light emitting portion as a focal point, light from the light emitting portion can be controlled in a desired radiation direction.
[0007]
The reflection type light emitting device according to claim 2 of the present invention, wherein the reflection surface is a paraboloid of revolution, and the paraboloid of revolution has at least a paraboloid having a first focal point on the axis of rotation; And a parabolic surface having a second focal point, wherein the parabolic surface having the first focal point and the parabolic surface having the second focal point have different focal lengths.
[0008]
Light emitted from the center of the light emitting element is reflected parallel to the rotation axis direction on a paraboloid having a first focus at the center of the light emitting element on the rotation axis, but the light emission surface located at a position deviated from the focus The light emitted from the light emitting portions on the peripheral portion and the side end surface is emitted in a direction different from the rotation axis direction, and it is difficult to control the light. Therefore, as described above, the parabolic surface having the first focal point at the center of the light emitting element and the parabolic surface having the light emitting portion at the peripheral portion of the light emitting surface or the side end face as the second focal point have different focal lengths. By providing them together, it is possible to control the light emission from other than the central part of the light emitting element, and it is possible to realize emitted light with higher directivity. Such an effect becomes more remarkable as the distance between the center of the light emitting element and the light emitting portion on the light emitting surface peripheral portion or the side end surface increases, that is, when the size of the light emitting element increases.
[0009]
In addition, by providing a reflective surface having a first focal point and a reflective surface having a second focal point in combination, it is possible to control so that light from the light emitting element is reflected in different directions or in the same radiation direction. Therefore, by selecting the control method, it is possible to expand the use applications.
[0010]
The reflection type light emitting device according to claim 3 of the present invention is a reflection type light emitting device in which light from the light emitting element is reflected in a radiation direction by a light emitting element and a reflecting surface provided so as to face the light emitting element. The surface is divided by a plane perpendicular to the central axis of the light emitting element, and has different focal points.
[0011]
With such a structure, light can be emitted in the central axis direction of the light emitting element.
[0012]
According to a fourth aspect of the present invention, in the reflective light emitting device, the reflective surface is provided with a first concave surface having a first focal point at the center of the light emitting surface of the light emitting element and a radial direction side of the first concave surface. And a second concave surface.
[0013]
With such a configuration, it is possible to control the light from the light emitting unit located in the radiation direction from the light emitting surface of the light emitting element.
[0014]
In the reflective light emitting device according to claim 5 of the present invention, the first concave surface is a paraboloid having a first focal point, and the second concave surface is a parabolic surface having a second focal point.
[0015]
In the reflection type light emitting device according to claim 6 of the present invention, the central axis of the light emitting element coincides with the rotation axis, and the paraboloid having the first focal point passes through the second focal point and is parallel to the rotation axis. It is provided from the intersection of the straight line and the paraboloid having the first focal point to the high angle side.
[0016]
With such a configuration, light from the light emitting surface can be efficiently reflected.
[0017]
In the reflective light-emitting device according to claim 7 of the present invention, the second focal point is located at least on the radial direction side than the first focal point, and is on the side end face of the light-emitting element.
[0018]
With such a configuration, light from the side end surface can be efficiently reflected in the radiation direction.
[0019]
In the reflection type light emitting device according to claim 8 of the present invention, the light emitting element has a third focal point on the radial direction side from the second focal point, and the parabolic surface having the second focal point has the third focal point. It is characterized in that the paraboloid has a more radial side.
[0020]
With such a configuration, it is possible to provide a reflecting surface according to the light distribution characteristics of each light emitting unit on the side surface.
[0021]
10. The reflective light-emitting device according to claim 9, wherein the light-emitting element is formed by stacking a gallium nitride-based compound semiconductor on a heterogeneous substrate, and the second focus is an active layer on a side end face of the light-emitting element. And a third focus is on the foreign substrate.
[0022]
With such a configuration, it is possible to control both the light emission from the side end surface of the light emitting element and the light emitted from the heterogeneous substrate.
[0023]
A reflective light emitting device according to a tenth aspect of the present invention is characterized in that the light emitting surface and the side end surface of the light emitting element are covered with a fluorescent substance.
[0024]
With such a structure, a desired light emission color such as white light emission can be obtained by mixing light from a light-emitting element and light from a fluorescent substance which emits light when excited by the light from the light-emitting element.
[0025]
A reflection type light emitting device according to an eleventh aspect of the present invention is characterized in that the reflection type light emitting device has a lens-shaped light-transmitting member on the radiation direction side of the reflection surface.
[0026]
With such a configuration, light reflected in the radiation direction by the reflection surface can be controlled again in a desired direction, so that the degree of freedom in designing increases.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
4 and 5 show an example of the structure of the reflective light emitting device according to the present embodiment.
The reflective light emitting device of the present invention includes a light emitting element 2, a mounting substrate 3 on which a wiring pattern for mounting the light emitting element is formed, and a heat conductive member 4 on which the mounting substrate is mounted. And a reflecting surface 1 provided so as to face the second light emitting surface 2a. A conductive member is provided on the surface of the heat conductive member 4, and a current can be supplied to the wiring pattern of the mounting board 3 by the conductive member. A current is supplied from the wiring pattern, and the light emitting element emits light toward the reflection surface. The reflection surface 1 reflects light emitted from the light emitting element and emits light in a radial direction. In the present invention, the direction of light reflected by the reflection surface 1 is defined as a radiation direction. Here, the present invention is characterized in that the light emitting element has a plurality of light emitting portions and the reflecting surface 1 also has a plurality of paraboloids as shown in FIG. Each paraboloid is formed as a paraboloid having each light-emitting portion as a focal point.
[0028]
(Reflection surface 1)
In FIG. 2, the light-emitting element 2 has two light-emitting portions, and the light-emitting portion on the light-emitting surface 2a is F1 and the light-emitting portion on the side end surface 2b is F2. Further, a reflection surface 1 having a paraboloid R1 having a focus on the light emitting portion F1 and an R2 having a focus on the light emitting portion F2 is formed. As described above, by making the reflecting surface 1 a surface composed of a plurality of paraboloids instead of a single surface, it is possible to efficiently control light from a plurality of light emitting units of the light emitting element.
[0029]
In FIG. 2, the case where there are two light emitting units and two parabolic surfaces has been described, but it is not always necessary to form the same number of parabolic surfaces as the number of light emitting units. For example, a light-emitting element having three light-emitting portions on a reflective surface having two paraboloids as shown in FIG. 2 can be used. In such a case, by forming the reflection surface so as to have a focus on the light-emitting portion having higher emission intensity among the three light-emitting portions, light can be more efficiently controlled than with a single reflection surface.
[0030]
In FIG. 1, a reflecting surface having three paraboloids is formed for a light emitting element having three light emitting units. By forming a parabolic surface in accordance with each light emitting portion in this manner, light can be reflected with better controllability.
[0031]
In the present invention, the reflection surface 1 is a paraboloid, and among them, it is particularly preferable that the reflection surface 1 is a paraboloid of revolution. The paraboloid of revolution is formed by rotating a parabola about a rotation axis. It is preferable that the reflecting surface be a paraboloid having a focal point on the rotation axis and a paraboloid having a focal point other than the rotation axis. For example, the reflection surface shown in FIG. 2 has a paraboloid of revolution R1 around the central axis 5 of the light emitting element. Further, it has a paraboloid of revolution R2 having a focal point at a position distant from the rotation axis 5, and the paraboloid of revolution R1 and the paraboloid of revolution R2 are formed so as to have different focal lengths from each other. If the focal point of the paraboloid of revolution R1 is the first focal point and the focal point of the paraboloid of revolution R2 is the second focal point, the second focal point is located outside the rotation axis. For example, there is a case where the light emitting unit is located at a position other than the center of the light emitting surface 2a of the light emitting element 2 or at the side end surface 2b.
[0032]
Due to the shape of the light-emitting element, the electrodes provided in the light-emitting element, or the configuration of each semiconductor layer, the light-emitting intensity is not uniform even with one light-emitting element. By forming a paraboloid so as to have a focus on a high emission intensity portion other than the center according to the emission intensity distribution of the light emitting element to be used, it is possible to cope with a light emitting element having many light emitting portions. In particular, since the intensity distribution appears substantially concentrically around the center of the light emitting element, a paraboloid of revolution as in the present invention can be used as a reflecting surface adapted to the intensity distribution of the light emitting element. .
[0033]
Here, when the light emission intensity distribution of the light emitting element does not become concentric, for example, when the shape of the light emitting element is rectangular (as viewed from the light emitting surface), a preferable focus cannot be selected on the paraboloid of revolution as described above. . In such a case, a reflecting surface having a plurality of surfaces divided by a plane perpendicular to the central axis of the light emitting element can be used. Even when the light emission intensity distribution of the light emitting element is substantially concentric, a reflection surface having a plane divided by a plane perpendicular to the central axis of the light emitting element is preferable, and the light emitting element can be formed so as to have different focal points. With such a configuration, it is possible to efficiently control the light emitted from other than the center of the light emitting surface of the light emitting element in the radiation direction.
[0034]
The surface divided by a plane perpendicular to the central axis of the light emitting element is preferably a concave surface. The plane is a reflecting surface that is divided into a first concave surface having a focal point at the center of the light emitting surface of the light emitting element and a second concave surface provided in a radial direction from the first concave surface. Can be. By setting the first concave surface to have the first focal point, light from the light emitting unit of the light emitting surface can be reflected by the first concave portion. The second concave surface does not need to have a particular focal point. However, if the focal point of the second concave surface is the second focal point and this focal point is set to a light emitting unit other than the first focal point, the second concave surface will be located at a position other than the center of the light emitting element. Can control the light from the When the first concave portion and the second concave portion are paraboloids, respectively, they correspond to the above-described parabolic surface having the first focal point and the parabolic surface having the second focal point.
[0035]
As shown in FIGS. 1 and 2, the paraboloid having the first focal point includes a straight line 6 passing through the second focal point and parallel to the central axis 5 (rotation axis), and a parabola having the first focal point. It is provided to the higher angle side than the intersection with the surface, in other words, the connection between the parabolic surface having the first focal point and the parabolic surface having the other focal point passes through the second focal point If it is formed at a higher angle than the intersection of the straight line 6 parallel to the rotation axis (the straight line in contact with the side end face of the light emitting element) and the reflecting surface, the light from the light emitting surface 2a is reflected without waste. It becomes possible. Furthermore, the emitted light from the light emitting unit located on the high angle side can be reflected in the radiation direction with more controllability. The effect of the present invention can be more remarkably obtained because the distance from the central axis 5 to the light emitting portion increases as the size of the light emitting element 2 increases. In the present invention, the central axis of the light emitting element is set to 0 °, the vicinity of the central axis is set to the low angle side, and the farther away from the central axis, the higher angle side.
[0036]
The above-described paraboloid has a focus position even when it has a light-emitting portion at a position away from the center axis 5 of the light-emitting surface 2a of the light-emitting element 2, particularly when it has a plurality of light-emitting portions on the side end surface 2b. By moving not only in parallel to the central axis 5 but also in the radial direction, it becomes possible to focus each light emitting unit. As described above, by forming a paraboloid having the light-emitting portion as a focal point according to the light-emitting characteristics of the light-emitting element, the reflected light in a desired radiation direction can be controlled to obtain a spotlight. Is also possible.
[0037]
The reflecting surface 1 is formed of a paraboloid of revolution obtained by rotating a parabola with the central axis 5 of the light emitting element 2 as a rotation axis. The parabola is a first parabola having a focal point F1 on the central axis 5 of the light emitting surface 2a of the light emitting element 2, a second parabola having a light emitting portion away from the central axis 5 as a second focal point F2, and a first and a second parabola. This is a continuous parabola in which a plurality of parabolas are connected, each having a different focus, such as a third parabola having a light-emitting portion other than the second focus as the focus F3. The reflective surface having such a shape of a paraboloid of revolution can be formed by cutting or injection molding with a mold using an acrylic resin or an epoxy resin as a material. It is also possible to form a paraboloid of revolution with a metal material, and in the case of a metal material, it is preferable to use aluminum or the like having a good thermal conductivity. The reflecting surface of the present invention can be obtained by coating the surface of the paraboloid of revolution formed as described above with a metal substance by plating, sputtering, vapor deposition or the like. It is preferable that the reflective surface is coated by sputtering or vapor deposition, because in addition to being able to be manufactured at a low cost, a mirror surface with extremely few irregularities can be formed with high accuracy, and the reflected light can be more uniformly extracted in the radiation direction. As the metal substance, a substance having a high reflectivity such as aluminum or silver is preferably used. However, a material having a high reflectivity can be selected according to the emission wavelength of the light-emitting element.
[0038]
The number of paraboloids whose focus is on the light emitting section is not limited, and can be appropriately selected according to the light emitting element used. Further, the size (diameter, depth) and the like of the above-mentioned reflecting surface are not limited, but can be selected according to the purpose and conditions to be used.
[0039]
When the reflecting surface 1 is provided at a higher angle side than the mounting surface of the light emitting element 2, that is, at a higher angle side (about 100 °) than 90 ° from the central axis, light emitted from the light emitting element 2 emits light. Further, since the light can be reflected by using the light, the luminance in a desired radiation direction can be increased.
[0040]
In the case of using a fluorescent material other than the method of applying a fluorescent material on the surface of the light emitting element 2 described above, various types of light emission can be achieved by performing color conversion by applying a fluorescent material to the reflective surface 1 or the like. Color can be obtained.
[0041]
The case where one light emitting element 2 is used has been described above. However, even when a plurality of light emitting elements 2 are used side by side, the present invention can be realized by forming the reflection surface 1 having a focus on the light emitting portion of each element arranged side by side. It is possible to achieve the embodiment of the present invention.
[0042]
In addition, by providing a lens-shaped light-transmitting member on the side of the reflecting surface in the radiation direction of light, parallel light obtained from the reflecting surface can be controlled in a desired radiation direction. It is also possible to have various directivities.
[0043]
(Light-emitting element 2)
In the present invention, the light emitting element 2 used is not particularly limited as long as it has a pair of positive and negative electrodes on the same surface side and can emit a part of light emission from the side end surface. Regarding the method of mounting on the mounting substrate 3, the substrate side of the light emitting element 2 can be used as a mounting surface and electrically connected by a conductive wire, or the electrode forming surface side of the light emitting element 2 can be connected to the mounting substrate. The electrodes of the light emitting element 2 and the wiring pattern formed on the mounting substrate 3 can be joined to each other via a conductive paste. As shown in FIG. 6, one light emitting element 2 may be used and placed on the mounting substrate, or a plurality of light emitting elements may be used, and the number is appropriately determined according to the purpose of use. The juxtaposition method is shown in FIGS. 7 and 8. When a plurality of light emitting elements 2 are used, the light emitting elements at the corners are juxtaposed in parallel with the adjacent surfaces of the elements being parallel (FIG. 7). Others can be changed so as to have a desired light distribution characteristic according to the application, for example, by arranging the light emitting elements at the corners by rotating the luminous elements by 45 ° (see FIG. 8) or by arranging only the light emitting elements at the corners by 45 °. In addition to the similar shape of the light emitting element, the directivity of light can also be expanded in the left-right direction by forming a substantially rectangular shape by arranging the mounting substrate 3 (heat conducting member 4) in one of the long sides in the longitudinal direction. Alternatively, a light emitting area may be set in advance, and the light emitting elements 2 may be arranged so as to be spread in the light emitting area. In this case, when the light emitting region is formed in a circular shape and one side end surface of each light emitting element 2 is positioned on the outer edge of the light emitting region, it is possible to form a substantially circular light source. The characteristics of light emission by the reflecting surface 1 can be further enhanced.
[0044]
Further, by using a plurality of light-emitting elements 2, light-emitting elements 2 having different emission colors can be alternately arranged to obtain various mixed color lights such as white light having good color rendering properties. The color mixing can also be improved by adjusting the order and height in consideration of the emission color of the light emitting element 2. Further, when adjusting the height of each light emitting element, the light extraction efficiency can be improved by making the mounting substrate 3 stepwise so that the light emitting elements are not shaded and light emission is not blocked. The distance between the light emitting elements 2 can be adjusted appropriately and arranged, and the size is not limited. When a light-emitting element having a large size is used, emission intensity can be increased.
[0045]
Examples of the laminated structure of the light emitting element 2 include a homostructure having a MIS junction, a PI junction, and a PN junction, a heterostructure, and a double heterostructure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal thereof. Further, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed as a thin film in which a quantum effect occurs can be used.
[0046]
When a gallium nitride-based compound semiconductor is used, a material such as sapphire, spinel, SiC, Si, or ZnO is preferably used for the semiconductor substrate. In order to form a gallium nitride-based compound semiconductor having good crystallinity with good mass productivity, it is preferable to use a sapphire substrate. A gallium nitride-based compound semiconductor can be formed on this sapphire substrate by MOCVD or the like. A buffer layer of GaN, AlN, GaAlN, or the like is formed on a sapphire substrate, and a gallium nitride-based compound semiconductor having a pn junction is formed thereon.
[0047]
As an example of a light emitting element having a pn junction using a gallium nitride-based compound semiconductor, a first contact layer formed of n-type gallium nitride and a first cladding layer formed of n-type aluminum-gallium nitride on a buffer layer , An active layer formed of indium gallium nitride, a second cladding layer formed of p-type aluminum gallium nitride, and a second contact layer formed of p-type gallium nitride. The gallium nitride-based compound semiconductor shows n-type conductivity without being doped with impurities. When a desired n-type gallium nitride-based compound semiconductor is formed, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, or the like as an n-type dopant. On the other hand, when a p-type gallium nitride-based compound semiconductor is formed, a p-type dopant such as Zn, Mg, Be, Ca, Sr, or Ba is doped. Since gallium nitride-based compound semiconductors are difficult to become p-type only by doping with a p-type dopant, it is preferable to lower the resistance by introducing a p-type dopant and then heating the furnace or irradiating plasma. After the electrodes are formed, a light emitting element made of a gallium nitride-based compound semiconductor can be formed by cutting the semiconductor wafer into chips.
[0048]
However, particularly when the active layer is made of a gallium nitride-based compound semiconductor containing indium and the like, the active layer containing indium having a relatively small band gap is sandwiched between cladding layers containing aluminum having a relatively large band gap. By repeating the propagation in the active layer, it is confined in the active layer, it is relatively hard to radiate from the light emitting surface 2a of the light emitting element 2, and the light emission intensity from the light emitting element end face 2b increases. In addition, light propagates without being transmitted at the interface between the electrode formed on the light emitting element and the element or the interface between different kinds of substrates such as sapphire, and the light emission from the end face 2b tends to be further promoted. .
[0049]
Further, the light emitting element 2 used in the embodiment of the present invention is formed by applying a fluorescent substance to the light emitting surface 2a and the side end face 2b of the light emitting element 2 or adding a fluorescent substance to the layer, for example. Various luminescent colors can be obtained by a combination of light generated by excitation light of the fluorescent substance.
[0050]
In particular, in the case of a configuration as shown in FIGS. 7 and 8 using a plurality of light-emitting elements, the fluorescent substance covers each light-emitting element individually with a uniform thickness so as to cover the light-emitting surface and the side end face. The directivity of light emission differs between the case where the coating is performed and the case where the coating is performed so as to cover all the juxtaposed light emitting elements. In particular, when a plurality of light-emitting elements are combined and juxtaposed to be used as a large-sized light-emitting element, a more desired directivity can be obtained by integrally covering each element with a phosphor. .
[0051]
The fluorescent substance that can be used in the present invention includes a photoluminescent phosphor that emits light when excited by an emission wavelength emitted from a light emitting element. As a specific example, YAG (YAG) such as YAG: Ce, which is a phosphor capable of emitting yellow light by blue light emission from a gallium nitride-based compound semiconductor, is used. ₂ O ₃ ・ 5 / 3Al ₂ O ₃ ) -Based phosphors. In the present invention, the YAG-based phosphor is to be interpreted particularly broadly, and is substituted with at least one element selected from Y, Lu, Sc, La, Gd and Sm, or a part or the whole of aluminum. , Ga, and In or both of them.
[0052]
Similarly, as a phosphor capable of emitting red light by blue light emission, a nitrogen-containing Ca-Al-Si-N-based oxynitride fluorescent glass activated with Eu and / or Cr may be mentioned. Note that the peak of the emission spectrum can be continuously shifted from 575 nm to 690 nm by increasing or decreasing the nitrogen content of the Ca-Al-Si-N-based oxynitride fluorescent glass activated with Eu and / or Cr. it can. Therefore, by combining light from a gallium nitride-based compound semiconductor containing GaN or InGaN doped with impurities such as Mg and Zn in a light-emitting layer and light of a phosphor of about 580 nm, white light similar to that of a YAG-based phosphor is generated. Obtainable.
[0053]
(Mounting board 3)
The mounting substrate 3 used in the present embodiment has a wiring pattern formed on the mounting surface side of the light emitting element 2. For example, a conductive material having good thermal conductivity is formed on the back surface of a heat conductive member 4 such as a heat pipe. When the light-emitting element is attached via an adhesive such as a paste, deterioration of the light-emitting element due to heat generation during light emission can be suppressed. Heat pipe, for example, in a metal tube made of a metal material having good thermal conductivity such as copper and aluminum, water, chlorofluorocarbon, alternative chlorofluorocarbon, a fluid for heat transport such as Fluorinert is sealed, The working fluid is heated in the heat input section (high temperature section) to become steam, and the vapor moves to the heat radiating section (low temperature section) and liquefies to release heat, and the liquefied working fluid is applied to the heat input section by capillary action. By repeating the operation of returning, extremely high thermal conductivity can be realized.
[0054]
Further, the heat pipe is connected to a heat sink or the like, so that the heat radiation effect of the reflection type light emitting device can be further enhanced.
[0055]
An insulating material made of ceramic or a material having a good thermal conductivity, in which a conductive wiring pattern is disposed on such a heat conducting member 4 by copper or gold for supplying power to the light source as described above. The light emitting element 2 is mounted and fixed on the wiring pattern by using silver paste or the like so as to face the reflection surface 1 and is electrically connected. With such a structure, heat dissipation can be improved, so that deterioration of the light-emitting element and changes in light-emitting characteristics can be suppressed, and a highly stable reflective light-emitting device can be obtained. Further, other than the insulating substrate, for example, an insulating film may be formed on a conductive substrate such as a metal substrate or a semiconductor substrate, and a wiring pattern may be formed on the insulating film.
[0056]
The heat conductive member 4 such as a heat pipe on which the mounting board 3 is provided can be processed into various shapes. Further, it is preferable that the size of the mounting substrate 3 is the minimum size necessary for disposing the wiring pattern so as not to block the irradiation light.
[0057]
In addition, it can also be implemented by directly printing a wiring pattern on the heat conducting member 4 such as a heat pipe via an insulating member.
[0058]
The reflective light-emitting device of the present invention having the above-described embodiment may be used alone, or by juxtaposing a plurality of light-emitting devices, it is possible to irradiate a wider range. It can be determined appropriately according to the intended use.
[0059]
【Example】
Hereinafter, embodiments according to the present invention will be described in detail. Note that the present invention is not limited to only the examples described below.
[0060]
(Example 1)
FIGS. 1, 4 and 5 show a schematic sectional view and a schematic perspective view of the reflection type light emitting device of the first embodiment. FIG. 9 is a graph showing the light distribution characteristics of the light emitting element used in this embodiment.
[0061]
In the reflection type light emitting device of the first embodiment, a 1 mm square light emitting element 2 made of a gallium nitride-based compound semiconductor grown on a sapphire substrate is mounted on a back surface of a heat pipe 4 made of copper. It was mounted on a copper pattern formed on the substrate 3 via a silver paste and electrically connected. The heat pipe 4 is fixed to the reflecting surface 1, and the light emitting element 2 is arranged such that the electrode forming surface side faces the reflecting surface, and the rotation axis of the reflecting surface center and the central axis 5 of the light emitting element are aligned. Are arranged. The reflection surface 1 is a paraboloid of revolution having a diameter of 30 mm, and is formed by depositing aluminum on a paraboloid of revolution formed by cutting an acrylic resin.
[0062]
As can be seen from the graph of FIG. 9, the relative intensity of light near 0 ° of the central axis, where the reflection surface is normally focused, is considerably lower than that of other parts of the light emitting element, and is rather 45 °. The peaks of the luminescence intensity are found at around ° and around 75 °, indicating that the luminescence intensity from these portions is high. Therefore, as compared with the amount of light emitted from the light emitting surface, which is the focal point of the reflecting surface, the intensity of light from the two light emitting portions (at angles of about 45 ° and 75 °) on the light emitting element end face located away from the central axis. Is high.
[0063]
From the light distribution characteristics described above, the paraboloid of revolution has a parabolic surface R1 having a first focal point F1 on the rotation axis (around 0 °) at the center of the light emitting surface 2a of the light emitting element 2; A parabolic surface R2 having a second focal point F2 on the active layer (around 75 °) on the lateral end face 2b, and a parabolic surface R3 having a third focal point F3 on the sapphire substrate (about 45 °) on the lateral end face of the light emitting element. It consists of the object surface R3. In addition, in consideration of the light distribution characteristics of the light emitting element 2, each paraboloid has a parabolic surface R1 having the first focal point F1 from the central axis 5 of the light emitting element 2 extending from 0 ° to 30 °. The parabolic surface R3 having the third focal point F3 is provided from 30 ° to 60 °, and the parabolic surface R2 having the second focal point F2 is provided from 60 ° to 100 °.
[0064]
By using the paraboloid of revolution according to the present embodiment, the light distribution characteristic as shown by the solid line A was shown in the graph of FIG. Although the emission intensity at an angle of 0 ° is represented as 1, the intensity sharply decreases as the angle increases, so that parallel light in the 0 ° direction is efficiently obtained. On the other hand, a dashed line B showing a light distribution characteristic from a reflecting surface having a single focus, which is a comparative example, has a light emission intensity near 0 ° of about 0.75, which is lower than the solid line A of the present example. Further, since the light corresponding to the intensity difference near 0 ° from the solid line A is reflected while being shifted from the 0 ° direction, the light having a single focal point often travels in a direction other than the 0 ° direction. You can see it exists.
[0065]
With the paraboloid of revolution according to the present embodiment, the side end face 2b located on the high angle side away from the vicinity of 0 °, which is the center of the light emitting surface 2a of the light emitting element 2, can be separated from the active layer and the sapphire substrate. The emitted light can also be efficiently reflected in the radiation direction. Therefore, since a more strict parallel light in which the direction of the light beam is aligned in the radiation direction can be obtained, a reflection type light emitting device having high luminance and directivity can be obtained.
[0066]
(Example 2)
FIG. 2 is a schematic sectional view of the reflection type light emitting device of the second embodiment.
[0067]
The reflection type light emitting device of this embodiment has a parabolic surface R1 having a first focal point F1 at the center of the light emitting element having the same light distribution characteristics as that of the first embodiment, and an active layer on the side end surface of the light emitting element. And a parabolic surface R2 having a second focal point F2. The parabolic surface having the first focal point is provided up to 30 °, and the parabolic surface having the second focal point is provided from 30 ° to 100 ° as in the first embodiment. Other configurations were formed in the same manner as in Example 1.
[0068]
By adopting the configuration of this embodiment, although the reflection efficiency is inferior to that of the first embodiment, the parabolic surface having the second focal point is provided from 30 °, so that the side of the light emitting element is particularly provided. Since the light emission from the end face can be efficiently controlled, the effect of the present invention can be obtained.
[0069]
【The invention's effect】
As described above, the reflection type light-emitting device of the present invention controls the light emitted from each light-emitting unit in the radiation direction since each of the light-emitting units on the light-emitting element has a reflective surface having a focal point. Since the light can be reflected, a reflective light-emitting device that can emit a high-intensity spot light can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a reflective light emitting device according to a first embodiment of the present invention.
FIG. 2 is a schematic sectional view of a reflective light emitting device according to a second embodiment of the present invention.
FIG. 3 is a schematic sectional view of a reflective light emitting device of a comparative example.
FIG. 4 is a schematic perspective view of a reflective light emitting device according to Examples 1 and 2 of the present invention.
FIG. 5 is a schematic sectional view showing AA in FIG. 4;
FIG. 6 is a schematic perspective view showing an example of a method for arranging light emitting elements according to the embodiment of the present invention.
FIG. 7 is a schematic perspective view showing an example of a method for arranging light emitting elements according to an embodiment of the present invention.
FIG. 8 is a schematic perspective view showing an example of a method for arranging light emitting elements according to the embodiment of the present invention.
FIG. 9 is a graph showing light distribution characteristics of a light emitting device used in an example of the present invention.
FIG. 10 is a graph showing light distribution characteristics of light reflected from a reflection surface according to Example 1 of the present invention and a comparative example.
[Explanation of symbols]
1: Reflective surface
2 ... Light-emitting element
2a: Light emitting surface
2b ... side end face
3. Mounting board
4 ... heat conduction member
5. Central axis of light emitting element

Claims (11)

A light-emitting element, a reflective light-emitting device that reflects light from the light-emitting element in a radiation direction by a reflection surface provided to face the light-emitting element,
The reflection type light emitting device, wherein the light emitting element has a plurality of light emitting portions, and the reflecting surface is formed by a plurality of paraboloids having the light emitting portions as focal points. The reflecting surface is a paraboloid of revolution, the paraboloid of revolution having at least a parabolic surface having a first focal point on a rotational axis and a parabolic surface having a second focal point away from the rotational axis. The reflective light emitting device according to claim 1, wherein the parabolic surface having the first focal point and the parabolic surface having the second focal point have different focal lengths. A light-emitting element, a reflective light-emitting device that reflects light from the light-emitting element in a radiation direction by a reflection surface provided to face the light-emitting element,
The reflection type light emitting device is characterized in that the reflection surface is divided by a plane perpendicular to the central axis of the light emitting element, and has different focal points. 4. The reflection surface according to claim 3, wherein the reflection surface includes a first concave surface having a first focal point at a center of the light emitting surface of the light emitting element, and a second concave surface provided on the radial direction side of the first concave surface. 5. Reflective light emitting device. The reflection type light emitting device according to claim 4, wherein the first concave surface is a paraboloid having the first focal point, and the second concave surface is a paraboloid having the second focal point. The central axis of the light emitting element coincides with the rotation axis, and the paraboloid having the first focal point passes through the second focal point and has a straight line parallel to the rotation axis and a parabolic surface having the first focal point. The reflective light-emitting device according to claim 2, wherein the light-emitting device is provided from the intersection with the object surface to a high angle side. 7. The reflection type light emitting device according to claim 2, wherein the second focal point is located at least on the radial side of the first focal point and is on a side end surface of the light emitting element. The light emitting element has a third focal point on the radial direction side from the second focal point, and the parabolic surface having the second focal point has a parabolic surface having the third focal point formed more radially. The reflection type light emitting device according to claim 2 or 5 to 7, wherein: The light emitting element is formed by stacking a gallium nitride-based compound semiconductor on a heterogeneous substrate, the second focus is on an active layer on a side end face of the light emitting element, and the third focus is on the heterogeneous substrate. The reflective light-emitting device according to claim 2, which is on a substrate. The reflective light emitting device according to claim 1, wherein a light emitting surface and a side end surface of the light emitting element are covered with a fluorescent substance. The reflective light emitting device according to claim 1, further comprising a lens-shaped translucent member on a radial direction side of the reflective surface.

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