JP4333440B2 - Surface emitting device - Google Patents

Description

  The present invention relates to a surface light emitting device using a light emitting diode and a light guide plate.

2. Description of the Related Art In recent years, surface light emitting devices that emit light from LED chips, which are point light sources, in a planar shape are used as light sources such as liquid crystal backlights. The surface light-emitting device is configured to allow light from one or more light-emitting diodes to enter from one end surface of a light guide plate having opposing main surfaces and to emit light from the entire one main surface of the light guide plate. .
The surface light emitting device configured using the light guide plate in this way emits light incident from one end surface of the light guide plate from one main surface to the entire surface, and thus how to emit light. It is important to ensure uniformity throughout.
Therefore, in the conventional light guide plate for a surface light emitting device, various devices such as forming dots set to a predetermined density on the light emitting surface or the reflecting surface facing the light emitting surface, or forming a prism on the reflecting surface, etc. Has been made.

JP 2001-108835 A

However, if the light from the light emitting diode leaks directly onto the light emitting surface without being incident on the light guide plate, the uniformity of the light on the light emitting surface cannot be ensured.
In particular, with the demand for thinning, such a problem is likely to occur when a flexible substrate having flexibility is used as a substrate for mounting a light emitting diode.

  Therefore, an object of the present invention is to provide a surface light emitting device having a structure in which light from a light emitting diode does not leak directly onto a light guide plate.

In order to achieve the above object, a surface light-emitting device according to the present invention has a first main surface and a second main surface, and a light guide plate having at least one end surface as a light incident surface, and one surface housing and the substrate on which the light-emitting diode is mounted, a bottom portion to which the second major surface of the light guide plate is arranged to face, the substrate having the light emitting diode is mounted on the light incident side of the light guide plate A surface emitting device that emits light of the light emitting diode incident from the light incident surface from the first main surface, wherein the storage portion is An end portion of the case is bent in a U-shape, and an encircling portion bent inside thereof is opposed to a part of the first main surface located on the light incident surface side of the light guide plate, A portion of the substrate positioned in front of the light emitting diode is the surrounding portion and the light guide plate And the surrounding portion has a substrate pressing portion that restricts a gap between the light guide plate and the substrate on a surface facing the first surface of the light guide plate. It is characterized by.

Further, in the surface emitting device according to the present invention, the substrate holding portion that is provided in contact with the inserted said substrate between the front Symbol enclosing portion and the first major surface of the light guide plate Is preferred.

  Further, in the surface light emitting device according to the present invention, the substrate pressing portion has a distance from the light emitting surface of the light emitting diode of 10% to 30% of a distance from the light emitting surface of the light emitting diode to the tip of the surrounding portion. It is preferable to be formed as follows.

  The surface light emitting device is provided along an outer periphery of the case, and the light guide plate is positioned at the bottom, and the substrate is positioned at the housing portion so that a light emitting surface of the light emitting diode faces the light incident surface. It is preferable to further include a light guide plate guide.

  In addition, the substrate pressing portion is preferably a convex portion having an arc shape in a cross section having a longitudinal direction perpendicular to the optical axis of the light emitting diode. With such a shape, the substrate can be effectively lifted. Thus, leakage of light can be prevented and a substrate or the like can be easily incorporated in the assembly process.

In the surface light emitting device according to the present invention, a portion of the substrate that is positioned in front of the light emitting diode is inserted between the surrounding portion and the light guide plate, and the clearance between the light guide plate and the substrate is limited to the surrounding portion. Since it has the board | substrate holding | suppressing part to perform, it can prevent effectively that the light of a light emitting diode leaks to the light emission surface of a light guide plate from the clearance gap between the said light guide plate and the said board | substrate.
Therefore, according to the present invention, it is possible to prevent light from leaking onto the light guide plate even when, for example, a flexible flexible substrate using polyimide or polyester as a material is used.

Hereinafter, a surface emitting device according to an embodiment of the present invention will be described with reference to the drawings.
The surface light emitting device according to the present embodiment includes a light emitting unit 4 and a light guide plate 5 each including a substrate 41 on which a light emitting diode 42 is mounted in a case 1, and transmits light emitted from the light emitting diode 42 on one side of the light guide plate. This is a surface light emitting device that emits light from a light emitting surface that is a main surface, and is configured as follows so that light from the light emitting diode 42 does not leak directly onto the light guide plate 5.

  In the present embodiment, the case 1 has a bottom portion 1 a on which the reflection sheet 2, the light guide plate 5, the diffusion sheet 6, and the prism sheet 7 are stacked and a storage portion 10 that stores the light emitting unit 4. . The storage portion 10 is configured by bending the end portion of the metal plate constituting the case into a U-shape, the rising portion 12 rising from the end of the bottom portion 1a at a substantially right angle, and the tip portion thereof being the bottom portion. It has the enclosure part 11 bent inward in parallel with 1a. The storage unit 10 is provided on the light incident surface 5 a side of the light guide plate 5, and the light emitting unit 4 is stored between the surrounding part 11 and the bottom part 1 a facing the surrounding part 11. The light emitting unit 4 is disposed in the storage unit 10 such that the light emitting surface of the light emitting diode 42 faces the light incident surface of the light guide plate.

In particular, in the present embodiment, a substrate pressing portion 11a that protrudes downward is provided on the lower surface of the surrounding portion 11, and the substrate 41 is pressed in front of the light emitting diode 42 by the substrate pressing portion 11a. The distance between the substrate 41 and the light guide plate 5 in front of 42 is not increased beyond a certain level.
Moreover, in this Embodiment, the cross section which has the longitudinal direction orthogonal to the optical axis of the light emitting diode 42 is formed in the circular arc shape in the board | substrate holding | suppressing part 11a. In the present invention, by forming the substrate pressing portion 11a in such a shape, it is possible to effectively prevent the substrate from floating and prevent light leakage, and to easily incorporate the substrate and the like in the assembly process.

Moreover, it is preferable to set the width | variety (width | variety of the direction orthogonal to a longitudinal direction) of the board | substrate holding | suppressing part 11a to the range of 0.5 mm-1 mm, and when set to this range, for example, the board | substrate holding | suppressing part 11a is formed by press work. Can be easily formed.
The position where the substrate pressing portion 11a is formed is formed such that the distance from the light emitting surface of the light emitting diode is 10% to 30% of the distance from the light emitting surface of the light emitting diode to the front end of the enclosing portion. Is more preferable, and more preferably, it is set in the range of 15% to 20%.
When the formation position of the substrate pressing portion 11a is set in such a range, the substrate pressing portion 11a can be easily formed by pressing or the like, and the substrate or the like can be easily incorporated.
Furthermore, in the surface light emitting device according to the present embodiment, it is preferable that the substrate pressing portion 11a is provided so as to be in contact with the substrate inserted between the enclosing portion and the light guide plate.

  Further, in the present embodiment, the light guide plate guide 3 is provided along the outer periphery of the case 1 in order to determine the positions of the light guide plate 5 and the light emitting unit 4 and maintain the positional relationship. The light guide plate guide 3 includes a side frame 3b, a back frame 3c, and a front frame 3a. A light guide plate is provided so as to be substantially in contact with the three sides of the side frame 3b and the back frame 3c. Between 5a and the front frame 3a, a space for accommodating the light emitting diode 42 mounted on the substrate 41 is formed.

  For example, the light emitting unit 4 is configured by providing the light emitting diode 42 on the back surface of the flexible substrate 41 in which wiring for applying a voltage to the light emitting diode 42 is provided. In the light emitting unit 4, the light emitting diode 42 is positioned between the light incident surface 5 a of the light guide plate 5 and the front frame 3 a so that the light emitting surface faces the light incident surface 5 a of the light guide plate 5. A portion located in front of the light emitting diode 42 is located between the surrounding portion 11 and the front end portion of the light guide plate 5, and a portion located behind the light emitting diode 42 in the flexible substrate 41 is located between the surrounding portion 11 and the front frame 3 a. It is provided so that it may be located.

The surface light emitting device of the present embodiment is manufactured as follows.
First, the light emitting unit 4 is prepared.
Specifically, side view type SMD type light emitting diodes in which LED dice are packaged are arranged (mounted) on the flexible substrate 41. In this side view type light emitting diode, positive and negative lead frames that can be electrically connected to LED dice are projected to the outside of the package so that the end portions of the lead frames are located on the same side of the package side surface. The light-emitting surface is perpendicular to the substrate surface when mounted, and light can be emitted parallel to the substrate surface.

  The LED dice mounted in the package are preferably arranged so that light emitting elements capable of emitting red, green, and blue (RGB) can be adjacent to each other in the package so that various emission colors can be selected. . As a light emitting element capable of emitting blue light, it is possible to emit light with high luminance by using a gallium nitride compound semiconductor. In addition to the above-described configuration, a light-emitting element used depending on usage can be selected as appropriate, for example, two colors are adjacent to each other or two or more LEDs are arranged for each color.

  The package used in the present invention is preferably one in which an LED die can be disposed at the bottom in the recess, and the thickness of the light-emitting device is highly dependent on the package of the light-emitting diode. Can be changed. As the material, various resins such as epoxy resin, silicone resin, imide resin, acrylic resin, PBT (polybutylene terephthalate), liquid crystal polymer, and aromatic nylon can be used. In particular, in order to efficiently extract light from the package, it is preferable to appropriately mix calcium carbonate, aluminum oxide, or titanium oxide as a light diffusing agent in the various resins. Thereby, a white package with a high reflectance can be constituted.

  When an LED die without a package is mounted and used as a light source, it can be emitted in a horizontal direction with respect to the mounting substrate and the bottom of the housing by using an edge-emitting LED. By using such an LED that does not have a package, the thickness of the package can be eliminated, so that the thickness can be further reduced.

  As the light emitting diode, a semiconductor light emitting element capable of various light emission can be used. Examples of the semiconductor element include those using a semiconductor such as GaP, GaAs, GaN, InN, AlN, GaAsP, GaAlAs, InGaN, AlGaN, AlGaInP, and InGaAlN for the light emitting layer. In addition, the semiconductor structure includes a MIS junction, a PIN junction, a homostructure having a PN junction, a heterostructure, or a double heterostructure.

  Depending on the material of the semiconductor layer and the mixed crystal ratio, various emission wavelengths of the semiconductor element from ultraviolet light to infrared light can be selected. Furthermore, in order to give a quantum effect, it can also be set as the single quantum well structure or the multiple quantum well structure which used the light emitting layer as the thin film.

  In addition, when used for a white backlight used in a liquid crystal panel or the like, not only the three primary colors of RGB, but also a light-emitting diode using a combination of light from a light-emitting element and a fluorescent material that is excited and emitted by this light is used. You can also. In this case, by using a fluorescent substance that converts to a long wavelength, it is possible to obtain a light emitting diode that can emit white light with good linearity by using one kind of light emitting element.

The fluorescent material used in the present invention converts light from the light emitting diode as described above, and is filled with a resin containing the fluorescent material when the light emitting element is placed in the package and then molded. The light emitted to the outside of the package can be converted. When the light from the light-emitting element is high-energy short-wavelength visible light, nitrogen-containing CaO—Al ₂ activated by a perylene-type derivative that is an organic phosphor, ZnCdS: Cu, YAG: Ce, Eu, and / or Cr. Various inorganic materials such as O ₃ —SiO ₂ are suitably used. Especially when YAG: Ce phosphor is used, light from the blue light emitting element and yellow color which is a complementary color by absorbing part of the light can be emitted depending on its content, and the white system is relatively easy and reliable. It is preferable because it can be formed well. Similarly, when a nitrogen-containing CaO—Al ₂ O ₃ —SiO ₂ phosphor activated with Eu and / or Cr is used, the light from the blue light emitting element and a part of the light are absorbed depending on the content. Thus, a red color which is a complementary color can emit light, and a white color can be formed relatively easily and reliably.

Also, components (case 1, reflection sheet 2, light guide plate guide 3, light guide plate 5, diffusion sheet 6, prism sheet 7) other than the light emitting unit 4 are separately prepared.
Each part is assembled as follows.
As a procedure for assembling, first, the reflection sheet 2 is placed on the bottom 1 a of the case 1.
The reflection sheet 2 improves light extraction efficiency of light emitted from the light emitting surface by reflecting light leaking from the other main surface of the light guide plate 5 upward.

Next, the light emitting unit 4 is disposed at a predetermined position of the light guide plate guide 3 so that a part of the back surface of the substrate 41 is in contact with the front frame 3a, and the light emitting unit 4 is guided so as to be disposed in the storage unit 10. The light guide 3 is assembled in the case 1.
Here, the terminal 41 a used for connection to the external circuit of the light emitting unit 4 is drawn out of the case 1 through the slit 12 a formed in the rising portion 12 of the storage portion 10.
Further, the rising portion 12 of the case 1 is provided with a leaf spring 12b for pressing and fixing the light guide plate guide 3 inward, and the light guide plate guide 3, the light emitting unit, and the light guide plate 5 move within the case 1. It is fixed so that there is no.

The light guide plate 5 is incorporated in the light guide plate guide 3 so that the light incident surface 5a faces the light emitting surface of the light emitting diode 42, and is fixed by bending a claw portion provided in the case 1 in advance. A diffusion sheet 6 and a prism sheet 7 are placed on 5.
The prism sheet 7 may be constituted by a plurality of prism sheets 7a and 7b as shown in the cross-sectional views of FIGS.

  In the surface light emitting device of the embodiment configured as described above, the substrate 41 is pressed in front of the light emitting diode 42 by the substrate pressing portion 11a formed in the surrounding portion 11, and the gap is limited. Light emission can be prevented from leaking onto the light guide plate 5.

That is, when the substrate pressing portion 11a is not provided, there is no problem when the back surface of the substrate 41 is substantially in contact with the upper surface of the light guide plate 5 (FIG. 5), but when the substrate 41 floats (FIG. 5). 6), light emitted from the light emitting diode 42 (indicated by an arrow) leaks directly to the light emitting surface through the gap between the substrate 41 and the light guide plate 5, and the light emitting surface on the light emitting unit side becomes abnormally bright.
On the other hand, in the present invention, the substrate holding part 11a is provided in the surrounding part 11 to hold the board 41 in front of the light emitting diode 42, thereby limiting the gap between the board 41 and the light guide plate 5 and floating the board 42. Even in such a case, the light emitted from the light emitting diode 42 is prevented from leaking directly to the light emitting surface.

It is possible to limit the gap between the substrate 41 and the light guide plate 5 by reducing the clearance between the surround portion 11 and the light guide plate 5 without providing the substrate pressing portion 11a in the surround portion 11. If it does in this way, in the process of incorporating the light emission unit 4 and the light-guide plate guide 3 in the accommodating part 10, workability | operativity will worsen and it will cause a manufacturing yield to deteriorate.
However, by providing the substrate pressing portion 11a as in the present invention, the light emitting surface of the light emitting diode 42 emits light while ensuring the clearance between the surrounding portion 11 and the light guide plate 5 to such an extent that the workability during manufacturing is not deteriorated. Leakage to the can be prevented.

  As described above in detail, the surface light emitting device according to the present embodiment is such that the portion of the substrate positioned in front of the light emitting diode is inserted between the surrounding portion and the light guide plate, and the light guide plate is provided in the surrounding portion. Since the substrate pressing part that restricts the gap between the substrate and the substrate is provided, light leakage from the gap between the substrate and the light guide plate can be prevented while ensuring good workability during manufacturing.

It is a perspective view which shows the structure of the surface emitting device which concerns on embodiment of this invention. It is a disassembled perspective view which shows the structure of the surface emitting device which concerns on embodiment of this invention. 1 is a perspective view (including a partial cross section) of a surface light emitting device according to an embodiment of the present invention. In the surface light-emitting device which concerns on embodiment of this invention, it is a perspective view (a partial cross section is shown) which shows the state by which the board | substrate is hold | suppressed. It is a perspective view (a partial cross section is included) of the surface emitting device of a comparative example. In the surface light-emitting device of a comparative example, it is a perspective view (a partial cross section is shown) which shows the state which the board | substrate floated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case, 1a Bottom part, 2 Reflection sheet, 3 Light guide plate guide, 3b Side frame, 3c Back frame, 3a Front frame, 4 Light emitting unit, 5 Light guide plate, 5a Light incident surface, 6 Diffusing sheet, 7 Prism sheet, 10 Storage Part 11 enclosing part 11a substrate pressing part 12 rising part 12a slit 41 substrate 42 light emitting diode.

Claims (7)

A light guide plate having a first main surface and a second main surface and having at least one end surface as a light incident surface;
A substrate with a light emitting diode mounted on one side;
Case made and a housing portion in which the second major surface of the light guide plate for housing a bottom portion opposed, the substrate on which the light emitting diode is mounted on the light incident side of the light guide plate A surface light emitting device that emits light from the light emitting diode incident from the light incident surface from the first main surface,
The storage portion is formed by bending the end of the case into a U-shape, and the encircling portion bent inside thereof is a part of the first main surface located on the light incident surface side of the light guide plate. And a portion located in front of the light emitting diode of the substrate is inserted between the surrounding portion and the light guide plate,
The surface light emitting device characterized in that the surrounding portion has a substrate pressing portion that restricts a gap between the light guide plate and the substrate on a surface facing the first main surface of the light guide plate. . The substrate holding portion front Symbol enclosing parts and inserted surface emitting device according to claim 1 wherein said is provided in contact with the substrate between said first main surface of the light guide plate.   The said board | substrate holding | suppressing part is formed so that the distance from the light emission surface of the said light emitting diode may be 10%-30% of the distance from the light emission surface of the said light emitting diode to the front-end | tip of the said enclosure part. 2. The surface light-emitting device according to 2.   A light guide plate guide provided along an outer periphery of the case, wherein the light guide plate is positioned at the bottom portion, and the substrate is positioned at the housing portion so that a light emitting surface of the light emitting diode faces the light incident surface. The surface light-emitting device as described in any one of Claims 1-3 provided. The surface light emitting device according to claim 4, wherein a portion of the substrate located behind the light emitting diode is inserted between the surrounding portion and the light guide plate guide. The substrate, the surface emitting device according to any one of claims 1 to 5 which is a flexible substrate. The substrate holding portion, the surface emitting device according to any one of claims 1 to 6 in cross-section a convex portion of the circular arc shape having a longitudinal direction perpendicular to the optical axis of the light emitting diode.

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