JP2008047851A - Linear light emitting device and surface light emitting device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a linear light emitting device and a surface light emitting device using it by utilizing light emitting elements which are point light sources. <P>SOLUTION: The linear light emitting device includes a rectangular mounting substrate, a plurality of light emitting elements arranged in a longitudinal direction on the mounting substrate, a fluorescent layer linearly covering the plurality of light emitting elements, and a sealing resin for covering the fluorescent layer. By forming the fluorescent layer so as to cover these light emitting elements, not only the light emitting elements but the fluorescent layer emit light with the light from the light emitting elements as excitation sources, thereby the linear light emitting device which linearly emits light is acquired. By covering it with the sealing resin, mechanical protection is possible. Further, by using the resin having refractive index smaller than that of the fluorescent layer, extraction efficiency of light is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a linear light emitting device and a planar light emitting device using the same.

In recent years, the luminous efficiency of light emitting diodes has been improved and replaced with CCFLs (cold cathode fluorescent lamps). The CCFL is a linear light-emitting device, whereas the light-emitting diode is a point light source. Therefore, when a planar light-emitting device is configured, there is a problem that uneven luminance occurs structurally. As a method for alleviating this problem, Patent Document 1 discloses a technique of mounting a plurality of light emitting elements in a row on a rectangular mounting substrate at high density and sealing with a sealing resin.
Japanese Patent Application Laid-Open No. 2002-299697.

  However, in order to mount the light emitting elements at a high density, as disclosed in Patent Document 1, a package having excellent heat dissipation must be used. Such a package itself is expensive, and since the light emitting elements are mounted at a high density, the cost of the package is also expensive, and the whole becomes extremely expensive. Furthermore, since it is necessary to supply power to the light emitting elements mounted at a high density, the electricity cost is also expensive. Therefore, both initial cost and running cost are expensive.

  An object of the present invention is to obtain a linear light-emitting device with little luminance unevenness even with a small number of light-emitting elements and a planar light-emitting device using the linear light-emitting device.

In order to achieve the above object, a linear light emitting device according to the present invention includes:
A rectangular mounting substrate, a plurality of light emitting elements arranged in the longitudinal direction on the mounting substrate, a phosphor layer covering at least the plurality of light emitting elements in a line, and a sealing resin covering the phosphor layer; Have.

  Thus, by forming a phosphor layer in a linear shape so as to cover a plurality of light emitting elements, not only the light emitting elements but also the phosphor layers between the light emitting elements emit light. Therefore, it is possible to realize a linear light emitting device that emits light linearly with a small number of light emitting elements. Moreover, mechanical protection becomes possible by covering these with sealing resin.

  Here, in the specification of the present application, the phosphor layer refers to a layer made of at least a phosphor and a translucent resin, and includes a substance containing a diffusing substance.

  In the linear light emitting device according to the present invention, the sealing resin has a semi-cylindrical shape. This has the effect of condensing light in a linear fashion.

  Moreover, the linear light-emitting device concerning this invention has the convex part in which the said sealing resin extends in the longitudinal direction of a mounting substrate, and the flat part extended to the side of this convex part. By having the convex portions, it is possible to optimize the light distribution characteristics.

  Further, by having the flat portion, the adhesion area is improved by increasing the adhesion area with the mounting substrate. Here, the flat portion includes those having irregularities and curved surfaces.

  In the linear light-emitting device according to the present invention, the convex portion has a semi-cylindrical shape. This has the effect of condensing light in a linear fashion.

  Here, the semi-cylinder means a shape obtained by cutting the cylinder in the length direction, and the curved surface includes not only a circle but also an ellipse and a part of a parabola.

  In the linear light emitting device according to the present invention, the phosphor layer is disposed below the convex portion. Thereby, light emission in the phosphor layer can be efficiently performed and the semi-cylindrical portion of the sealing resin can be passed.

  In the linear light emitting device according to the present invention, the sealing resin has a semi-cylindrical shape. This has the effect of condensing light in a linear fashion.

  In the linear light emitting device according to the present invention, the convex portion is wider than the phosphor layer. Thereby, light emission in the phosphor layer can be efficiently performed and the semi-cylindrical portion of the sealing resin can be passed.

  In the linear light emitting device according to the present invention, the phosphor layer has a semi-cylindrical shape. As a result, it is possible to develop an effect of condensing light in a linear manner at the interface between the phosphor layer and the sealing resin.

  In the linear light emitting device according to the present invention, the semi-cylindrical curvature radius of the sealing resin is larger than the semi-cylindrical curvature radius of the phosphor layer. This makes it possible to optimize refraction at the interface between the semicylindrical portion of the phosphor layer and the sealing resin.

  In the linear light emitting device according to the present invention, the mounting substrate has a rectangular recess in the longitudinal direction, and the plurality of light emitting elements and the phosphor layer are included in the recess. As a result, the concave portion has the effect of a reflector, and by controlling the light distribution characteristics, it is possible to reduce the optical loss and improve the light emission efficiency when optically connected to the light guide plate. Furthermore, by forming the phosphor layer in the recess, it is possible to make the thickness of the phosphor layer constant, and it is possible to reduce the chromaticity variation for each linear light emitting device.

  In the linear light emitting device according to the present invention, the concave portion has a wall that forms the concave portion in the longitudinal direction, and does not have a wall that forms the concave portion on the end surface in the short direction of the linear light emitting device. As a result, it is possible to obtain a narrow light distribution in the short direction and a wide light distribution in the longitudinal direction of the linear light emitting device.

  Furthermore, the planar light emitting device according to the present invention includes a light guide plate having a light incident portion, and the linear light emitting device according to any one of claims 1 to 10 optically connected to the light guide plate. It is characterized by providing. Since the linear light source can be realized by using the linear light-emitting device according to any one of claims 1 to 10, the luminance unevenness problem hardly occurs when the linear light-emitting device is used in a planar light-emitting device. .

  Furthermore, in the planar light emitting device according to the present invention, the light incident portion of the light guide plate has a concave portion, and the concave portion and the sealing resin are engaged with each other. Thereby, alignment of a linear light-emitting device and a light-guide plate becomes easy.

  Furthermore, in the planar light emitting device according to the present invention, the concave portion has a semi-cylindrical shape. This makes it possible to reduce optical loss.

  According to the present invention, it is possible to realize an inexpensive linear light-emitting device that generates little heat using a light-emitting element that is a point light source and a planar light-emitting device using the linear light-emitting device.

  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 light guide plate and the surface light-emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light guide plate and the surface light-emitting device below. . Further, the size and positional relationship of the members shown in the drawings are exaggerated for clarity of explanation.

<First Embodiment>
FIG. 1 shows a linear light-emitting device 1000 according to the first embodiment. In order to clearly show the internal structure, a transparent portion is shown. FIG. 3 shows a manufacturing process of the linear light-emitting device in the first embodiment.

  Reference numeral 101 denotes a light emitting element. Although the light emitting element has a rectangular shape, the shape is not limited to this, and a square shape or the like can also be used. The rectangular light emitting element can be mounted in a direction perpendicular to the longitudinal direction as shown in FIGS.

  The merit in this case is that the stress generated between the light emitting element and the mounting substrate can be reduced.

  As shown in FIG. 2, it is also possible to mount in a direction in which the longitudinal direction is aligned with the mounting substrate.

  The merit in this case is that the light emitting elements can be arranged more finely, and the phosphor layer can be formed with a narrow width. This facilitates optical design when the sealing resin has an effect of condensing light that diffuses in the circumferential direction into a linear shape.

  Furthermore, as shown in FIG. 13, it is possible to mount in an oblique direction with respect to the mounting substrate.

  In this case, the merit is that the thickness of the phosphor layer between the adjacent light emitting elements is changed, so that the chromaticity can be adjusted.

  Furthermore, as shown in FIG. 14, it is also possible to alternately mount light emitting elements mounted in a direction in which the longitudinal direction is aligned with the mounting substrate and light emitting elements mounted in a direction perpendicular to the longitudinal direction.

  The merit in this case is that the thickness of the phosphor layer with respect to each light emitting element can be reduced by alternately mounting the light emitting element mounted in the direction in which the longitudinal directions are aligned and the light emitting element mounted in the direction orthogonal to the longitudinal direction. As a result, the luminance unevenness and the chromaticity unevenness can be further reduced.

  The manufacturing process will be described with reference to FIG. A perspective view and a side view are shown correspondingly. FIG. 3A illustrates the mounting substrate 303.

  FIG. 3B is a diagram showing a state in which the light emitting element 301 is mounted on the mounting substrate. In order to ensure sufficient heat dissipation for the light emitting element, it is preferable to mount the light emitting element on the electrode. In this case, it is preferable that a eutectic metal is formed on the light emitting element side and mounted by using a eutectic bond with the electrode. Generally, the electrode is made of metal, so it has high heat dissipation and can serve as a heat sink. Furthermore, mounting on the metal called electrode has higher adhesive strength than bonding with eutectic metal rather than bonding with resin. Because.

  Thereafter, wire bonding is performed to electrically connect the electrodes.

  In addition, as shown in FIG. 11, the light emitting element 1101 can be mounted on a mounting substrate instead of on an electrode. In this case, since it becomes possible to use resin as a bonding agent, it becomes possible to mount simply and inexpensively.

  FIG. 3C illustrates a state where the phosphor layer is formed. When the phosphor layer is formed by a dispenser, the phosphor layer becomes a semi-cylindrical shape. The curvature of the semi-cylindrical portion of the phosphor layer can be designed according to the viscosity and surface tension of the translucent resin, the height of the wire, and the like. If the curvature of the semi-cylindrical portion of the phosphor layer is to be reduced, it can be realized by using a resin having a high viscosity, using a resin having a large surface tension, or increasing the height of the wire. This phosphor layer emits linear light when energized. The width of the line emission line is caused by the width of the phosphor layer.

  When the phosphor layer is formed not by line potting but by line printing, the phosphor layer is formed in a rectangular shape as shown in FIG. Thereby, since it becomes possible to cover a light emitting element with a fluorescent substance layer by uniform thickness, chromaticity nonuniformity can further be reduced. The phosphor layer can be controlled by the mask shape and thickness used for printing.

  As the arrangement position of the phosphor layer, it is most preferable to form the phosphor layer so as to cover all the light emitting elements as shown in FIG. This is because the light from all the light emitting elements can be used after being converted in wavelength by the phosphor layer. Further, as shown in FIG. 12, it is possible to adopt a structure in which the light emitting element 1201 does not cover a part of the plurality of light emitting elements with the phosphor layer. With this configuration, when the planar light emitting device is configured, when the linear light emitting device is fitted to the light guide plate, the light emitting element not covered with the phosphor layer can be used for alignment.

  FIG. 3D is a view showing a state in which a sealing resin that covers the phosphor layer is formed on the phosphor layer. The shape of the sealing resin is such that it encloses the light emitting element and the phosphor layer.

  The sealing resin can be molded by transfer molding, compression molding, casting molding, or the like. When the sealing resin has a semi-cylindrical shape or the convex portion has a semi-cylindrical shape, an effect of condensing light in a linear shape is exhibited. The semi-cylindrical curvature is preferably smaller than the curvature of the phosphor layer. When the light is condensed linearly, it can be efficiently incident on the light guide plate when applied to a planar light emitting device. As for the shape of sealing resin, it is preferable that a convex part is a semi-columnar shape like FIG.3 (e), and has a flat part in the side of a convex part. By providing the flat portion, the adhesion with the mounting substrate is improved, and when the color-shifted light emitted from the side of the light-emitting element is used as the planar light-emitting device, a configuration that is not used is possible. Furthermore, the convex portion may adopt a rectangular shape or a trapezoidal shape when viewed from the side as shown in FIGS. The light distribution characteristics can be optimized according to the purpose. Further, a configuration in which the entire sealing resin is a semi-cylindrical shape as shown in FIGS. 7 and 8 is also possible. In this case, the light emitted from the side of the light emitting element can also enter the light guide plate effectively. As shown in FIG. 8, the mounting substrate is wide enough to correspond to the semi-cylindrical portion, so that it can be thinned as a linear light emitting device, and can be thinned when used in a planar light emitting device. Become.

  FIG. 3 (e) is a state diagram showing the transparent portion of FIG. 3 (d).

Below, each structural member is described.
(Light emitting element)
A light-emitting element is a device in which a semiconductor such as GaAlN, ZnO, ZnSe, SiC, GaP, GaAlAs, AlN, InN, AlInGaP, InGaN, GaN, or AlInGaN is formed on a substrate as a light-emitting layer.

(Mounting board)
As a configuration of the mounting substrate, it is only necessary that the mounting surface has a rectangular shape and an electrode that can supply electricity to the light emitting element to be mounted. Examples of the substrate include a ceramic substrate, a glass epoxy substrate, an aluminum base substrate, a copper base substrate, a printed substrate, and a flexible substrate.

(Phosphor layer)
As the phosphor layer, a mixture of a translucent resin and a phosphor is used. More preferably, a diffusing material is contained. As the phosphor, a phosphor containing a phosphor that emits light having different wavelengths by absorbing at least a part of light from the light emitting element. In particular, it is more efficient to convert light from the light emitting element into a longer wavelength. When the light from the light-emitting element is short-wavelength visible light with high energy, YAG: Ce, which is a kind of aluminum oxide phosphor, is preferably used. In particular, the YAG: Ce phosphor is a high-power line that emits white-colored mixed light because it emits yellow-colored light that partially absorbs blue-colored light from the light-emitting element depending on its content. The light emitting device can be formed relatively easily.

  As the translucent resin, silicone resin, epoxy resin, acrylic resin, or the like is used. Preferably, gelled silicone is used. This is because there is little deterioration and the wire can be protected from mechanical shock.

  Examples of the diffusing material include barium titanate, titanium oxide, aluminum oxide, silicon oxide, silicon dioxide, heavy calcium carbonate, light calcium carbonate, and a mixture containing at least one of these.

(Sealing resin)
As the sealing resin, silicone resin, epoxy resin, acrylic resin or the like is used. Epoxy resins are preferably used. Optimum conditions are that the phosphor layer is a silicone resin and the sealing resin is an epoxy resin. Regarding the relationship between the refractive indexes, since the refractive index of the epoxy resin is larger than that of the silicone resin, it is possible to reduce the light distribution characteristic by reducing the curvature of the epoxy resin.

(electrode)
A metal is generally used as an electrode material. Copper is preferably used, and copper formed with silver on the surface is also preferably used. Other than metal, ITO is also used.

  The electrode can be formed by electrolytic plating, electroless plating, vapor deposition, sputtering, or the like.

<Second Embodiment>
4 and 5 show a planar light emitting device 4000 according to the second embodiment. The linear light emitting device is indicated by 3000. The light guide plate is represented by 409. The linear light emitting device 3000 and the light guide plate 409 are disposed in an optically connected state. The light incident portion of the light guide plate may have a planar shape, but preferably has a shape that fits with the sealing resin portion of the linear light emitting device. That is, it is preferable that the light incident portion of the light guide plate has a semi-cylindrical recess. This is because if the air layer is interposed between the linear light emitting device and the light guide plate, the light incident efficiency is lowered. It is preferable that the curvature of the semi-cylindrical recess in the light entrance is the same as or larger than the curvature constituting the semi-cylindrical shape of the sealing resin of the linear light emitting device. In the case where the sealing resin of the linear light emitting device is made of a hard resin, and the light guide plate is hard, it is preferable that the curvatures of the light emitting plates are almost completely aligned.

  On the other hand, when the sealing resin is a soft resin, or when the light guide plate is soft, it is preferable to increase the curvature of the light guide plate. This is because it is possible to extrude the air layer in the process of mechanically pressing when joining each other.

(Light guide plate)
Examples of the material of the light guide plate include acrylic resin, polycarbonate resin, amorphous polyolefin resin, polystyrene resin, norbornene resin, and cycloolefin polymer (COP).

<Third Embodiment>
15 and 16 show linear light-emitting devices 15000 and 16000 in the third embodiment. In the third embodiment, the mounting substrate has a rectangular recess in the longitudinal direction, and the plurality of light emitting elements and the phosphor layer are included in the recess. The concave portion includes bottom portions 1513a and 1613a and wall portions 1513b, 1513c, 1513d, 1613b and 1513c. The method of forming the recesses can be selected as appropriate, but can be easily implemented by adopting a ceramic laminated structure. For example, in FIG. 15, a mounting substrate 1503 is realized by laminating five ceramic sheets 1503a, 1503b, 1503c, 1503d, and 1503e. Each ceramic sheet is punched into a predetermined shape, and a predetermined electrode pattern is applied by electrolysis / electroless plating, etc., stacked on each other, and sintered in a laminated state. As a result, a mounting substrate having a recess is obtained.

  The depth of the recess and the angles of the walls 1513b and 1513c are appropriately selected according to the intended light distribution characteristics and the thickness of the phosphor layer.

  Further, by not providing the wall of the concave portion in the short direction, it is possible to widen the light distribution characteristic in the longitudinal direction as a linear light source. By providing wide light distribution characteristics in the longitudinal direction, luminance unevenness can be reduced when a planar light source is optically connected to the light guide plate.

  When the protective element is mounted, it may be mounted on the same surface as the light emitting element as shown in FIG. 16, or it is one step higher than the light emitting element as shown in FIG. Also good.

  Since the protective element generally has a property of absorbing light, the light distribution characteristics are different between when it is sealed inside the phosphor layer and when it is exposed from the phosphor layer. When the concave portion is divided by the central wall as shown in FIG. 15 and a protective element is mounted on the upper portion of the central wall, the luminance of the central portion can be lowered, and such light distribution characteristics are required. Useful.

  According to the present invention, it is possible to realize a linear light-emitting device and a planar light-emitting device using the light-emitting element, which is a point light source, more inexpensively than in the past.

It is a figure which shows one Embodiment of the linear light-emitting device which concerns on this invention. It is a figure which shows one Embodiment of the linear light-emitting device which concerns on this invention. It is a figure which shows the manufacturing method of the linear light-emitting device which concerns on this invention. It is a figure which shows one Embodiment of the planar light emission source which concerns on this invention. It is a figure showing the variation of the light-incidence part of the light-guide plate of the planar light-emitting device concerning this invention. It is a figure which shows one Embodiment of the linear light-emitting device which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention. It is a figure which shows one Embodiment of the linear light emission light source which concerns on this invention.

Explanation of symbols

101,201,301,1101,1201,1301,1401,1501,1601 ・ ・ ・ Light emitting element
103,203,303,803,1503,1603 ・ ・ ・ Mounting board
1503a, 1503b, 1503c, 1503d, 1503e, 1603a, 1603b, 1603c, 1603d, 1603e ・ ・ ・ Each layer constituting the mounting board
105,205,305,605,1105,1205,1305,1405,1505,1605 ... phosphor layer
107,207,307,707,907,1007,1107,1207,1307,1407,1507,1607 ・ ・ ・ Sealing resin
307a, 907a, 1007a, 1507a, 1607a ... convex
307b, 907b, 1007b, 1507b, 1607b ・ ・ ・ Flat part
409 ... Light guide plate
111a, 111b, 211a, 211b, 311a, 311b, 1111a, 1111b, 1211a, 1211b, 1311a, 1311b, 1411a, 1411b, 1511a, 1511b, 1611a, 1611b ...
1513,1613 ・ ・ ・ Recess
1513a, 1513b, 1513c, 1513d, 1613a, 1613b, 1613c ... Walls forming recesses
1515,1615 ... Protective element
1000, 2000, 3000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000 ... Linear light emitting devices
4000 ... Surface emitting device

Claims (13)

A rectangular mounting board;
A plurality of light emitting elements arranged in a longitudinal direction on the mounting substrate;
A phosphor layer covering at least the plurality of light emitting elements in a line;
A sealing resin covering the phosphor layer;
A linear light emitting device having:   The linear light-emitting device according to claim 1, wherein the sealing resin has a semi-cylindrical shape.   The linear light-emitting device according to claim 1, wherein the sealing resin has a convex portion extending in a longitudinal direction of the mounting substrate and a flat portion extending to a side of the convex portion.   The linear light-emitting device according to claim 3, wherein the convex portion has a semi-cylindrical shape.   The linear light-emitting device according to claim 3 or 4, wherein the phosphor layer is disposed below the convex portion.   The linear light-emitting device according to claim 3, wherein the convex portion is wider than the phosphor layer.   The linear light-emitting device according to claim 1, wherein the phosphor layer has a semi-cylindrical shape.   The linear light-emitting device according to claim 7, wherein the sealing resin has a semi-cylindrical radius of curvature larger than a semi-cylindrical radius of curvature of the phosphor layer.   The linear light emission according to claim 1, wherein the mounting substrate has a rectangular recess in a longitudinal direction, and the plurality of light emitting elements and the phosphor layer are included in the recess. apparatus.   The linear light-emitting device according to claim 9, wherein the concave portion has a wall that forms the concave portion in a longitudinal direction, and does not have a wall that forms a concave portion on an end surface in a short direction of the linear light-emitting device. A light guide plate having a light incident portion;
The linear light-emitting device according to any one of claims 1 to 10, optically connected to the light guide plate,
A planar light emitting device comprising:   The planar light-emitting device according to claim 11, wherein the light incident portion of the light guide plate has a concave portion, and the concave portion and the sealing resin are engaged with each other.   The planar light-emitting device according to claim 11 or 12, wherein the concave portion has a semi-cylindrical shape.

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