JP2007193946A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device performing superb heat radiation with excellent luminous efficiency. <P>SOLUTION: The light-emitting device, provided with a light source 7 consisting of a light-emitting diode, a light guide plate 4 having a light-receiving face 43a guiding in light from the light source 7 and an irradiation face 41 emitting light in plane with the light guided from the light-receiving face 43a, a circuit board 6 supplying power to the light source 7, and a frame 1 housing the light source 7 and the light guide plate 4, is also provided with a heat radiation member 8 in contact with a peripheral part of the frame 1 and separated from a center part of the frame 1 to form a space part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting device that illuminates a light-receiving display panel made of, for example, a liquid crystal panel, and more particularly to a light-emitting device that uses a light-emitting diode as a light source.

  This type of light source device is called a backlight device that illuminates the light receiving display panel from the back or a front light device that illuminates the light receiving display panel from the surface, and various devices have been proposed.

For example, the thing of the following patent document 1 is known as an example of a backlight apparatus. The backlight device supports the plurality of light emitting diodes, a light guide plate extending along the liquid crystal panel, a plurality of light emitting diodes opposed to each other along a side end surface (light receiving surface) of the light guide plate, and And a circuit board for supplying power. And the soft metal sheet is provided in the surface opposite to the surface of the circuit board which mounted the said light emitting diode. A metal having high thermal conductivity is used for the circuit board and the soft metal sheet, and heat generated by the light emitting diode is radiated.
Japanese Patent Laid-Open No. 2002-229022

  By the way, in a light emitting device using a light emitting diode as a light source, it is necessary to take measures against heat of the light emitting diodes in order to ensure the light emission efficiency and lifetime, and conventional heat radiation measures have been taken. However, even if such heat countermeasures are taken, if the luminance unevenness is further reduced and high luminance is to be obtained, the number of light emitting diodes is increased or a light emitting diode with high power consumption is used. Then, sufficient heat dissipation is not performed by the conventional heat countermeasures, and new problems such as a decrease in light emission efficiency of the light emitting diode and deformation due to heat of the light guide plate of the light emitting device occur.

  Therefore, an object of the present invention is to provide a light emitting device that performs good heat dissipation and has high luminous efficiency.

In order to achieve the above object, the present invention provides
A light source comprising a light emitting diode;
A light guide plate having a light receiving surface for introducing light from the light source and an irradiation surface for emitting light by light introduced from the light receiving surface;
A circuit board for supplying power to the light source;
In a light emitting device comprising a frame for housing the light source and the light guide plate,
A heat dissipating member that is in contact with a part of the frame and that forms a space with the frame is provided.

The present invention also provides
A ventilation portion connected to the space portion is provided.

The present invention also provides
The heat dissipation member is in contact with a part of the frame corresponding to the light source.

  According to the present invention, it is possible to achieve an initial object, to perform a good heat dissipation, and to provide a light emitting device having a high luminous efficiency.

  Embodiments will be described below with reference to the drawings, taking as an example a display device to which a light emitting device according to the present invention is applied.

  The display device according to this embodiment includes a frame 1, a display panel 2, an optical film 3, a light guide plate 4, a reflective film 5, a circuit board 6, a light source 7, a heat radiating member 8, a heat conductive sheet ( (Thermal conductor) 9 and 10.

  The frame 1 is composed of an upper frame 1a and a lower frame 1b. The upper frame 1a is composed of a light-shielding synthetic resin, and positions and supports each of the display panel 2 and the optical film 3.

  The lower frame 1b is made of a metal material, and is formed by bending each end portion of a substantially ten-shaped plate material so that the cross-sectional shape is substantially L-shaped, thereby forming a bent portion 1b1. In combination with the optical film 3, the light guide plate 4, the reflective film 5, the light source 7, and the heat conductive sheet (heat conductor) 9. , It functions as a back cover or chassis that supports each of these components from the back side. Further, the locking piece 1b2 for positioning the light guide plate 5 is arranged in a direction perpendicular to the direction in which the plurality of light sources 7 are arranged so as to form a space (air layer) between the light guide plate 5 and the light source 7. Each extending bent portion 1b1 is provided. In the present embodiment, the locking piece 1b2 is formed by bending a side end portion on the light source 7 side of each bent portion 1b1 extending in a direction perpendicular to the direction in which the plurality of light sources 7 are arranged.

  The display panel 2 is composed of, for example, a TFT (thin film transistor) type liquid crystal display panel, and displays predetermined information as the light source 7 is turned on.

  The optical film 3 is, for example, arranged on the light guide plate 4 on the back side of the display panel 2 so that the two prisms for increasing brightness in which the prism rows having a triangular cross section are formed at regular intervals are orthogonal to each other. Has been.

  The light guide plate 4 includes, for example, a transparent resin (for example, acrylic resin) having a good light transmittance, an irradiation surface 41, an opposing surface 42 facing the irradiation surface, and four connecting the opposing surface 42 and the irradiation surface 41. It is formed in a rectangular plate having a side end face 43 and is disposed on the back side of the display panel 2 with the optical film 3 interposed therebetween.

  The irradiation surface 41 is a flat surface extending along the panel surface (back surface side) of the display panel 2, and the facing surface 42 is a flat surface extending in parallel with the irradiation surface 41. Of the four side end surfaces 43, a predetermined (one in this case) side end surface 43 is formed as a light receiving surface 43 a that faces the light source 7 with a space and takes light from the light source 7 into the light guide plate 4. Has been. The irradiation surface 41 emits light with the light taken from the light receiving surface 43a.

  In addition, by providing the locking piece 1b2 on the lower frame 1b, separating the light guide plate 4 from the light source 7, and providing a space (air layer) between the light guide plate 4 and the light source 7, for example, the light source 7 itself When the heat-resistant temperature is high, if the power consumption of the light source 7 is large, the temperature of the light source 7 may become very high. Under such circumstances, the light guide plate 4, particularly the light receiving surface 43a and the optical film 3 in the vicinity thereof. The deformation of the light source 7 can be suppressed, and the performance of the light source 7 can be sufficiently extracted. The locking piece 1b2 provided on the lower frame 1b may be provided not only on the lower frame 1b but also on the upper frame 1a.

  The reflective film 5 is made of, for example, a white synthetic resin film, and is disposed on the back side of the light guide plate 4 so as to be in close contact with the facing surface 42, and reflects the light in the light guide plate 4 toward the irradiation surface 41.

  The substrate of the circuit board 6 has flexibility. As a base material, it consists of synthetic resins which have flexibility, such as a polyimide, for example. A wiring pattern (not shown) is provided on the base material. The wiring pattern forms at least a power supply path to the light source 7. In the present embodiment, since the plurality of light sources 7 are used, the wiring pattern is complicated. However, since the wiring pattern is not a multilayer but a single layer, the planar area is widened, and the lower frame 1b. The circuit board 6 disposed along the bent portion 1b1 passes the base of the bent portion 1b1, and is further disposed along the lower frame 1b toward the light guide plate 5 side. In this way, a plurality of penetrating cuts 61 are provided in the bent portion of the circuit board 6 as easy-to-bend portions so that the circuit board 6 follows the shape of the lower frame 1b. In addition, in order to make it easy to bend so that the circuit board 6 follows the shape of the lower frame 1b, in addition to the cut 61, it may be a perforation. By providing the easy-bending portion such as the cut 61, the circuit board 6 can be brought into close contact with the lower frame 1b. By bringing the circuit board 6 into close contact with the lower frame 1b, the heat from the light source 7 provided on the circuit board 6 can be better transferred to the lower frame 1b. Further, since the wiring pattern of the circuit board 6 is a single layer, the thickness of the circuit board 6 can be reduced, and because the circuit board 6 is thin, the circuit board 6 is flexible and conforms to the shape of the lower frame 1b. In addition, since it is thin, the heat of the light source 7 can be better transferred to the lower frame 1b. In addition, as a base material of the circuit board 6, other synthetic resin of a polyimide may be used, and metal foils, such as aluminum, may be used as a base material.

  The light source 7 is composed of a so-called top-view type surface-mounted light-emitting diode chip in which the light-emitting surface (described later) faces the light-receiving surface 43a of the light guide plate 4 and the side opposite to the light-emitting surface is a conductive portion (described later). A plurality are arranged. Each of these light sources 7 includes a housing 72 made of an insulating synthetic resin material provided with a recess 71 opened on one surface, a semiconductor light emitting element (bare chip) (not shown) disposed in the recess 71 of the housing 72, and the semiconductor A wiring member (not shown) serving as a power common path to the light emitting element is provided. The light emitting surface 73 is disposed opposite to the light receiving surface 43 a of the light guide plate 4 with the release side of the recess 71 as the light emitting surface 73. The recess 71 is sealed with a light-transmitting resin such as an epoxy resin or a silicone resin.

  The heat radiating member 8 is made of metal, and is provided on the back side (lower side in FIG. 2) of the lower frame 1b. The heat radiating member 8 has a flat plate shape, and a part thereof, in this case, a peripheral part (outer peripheral part) 81 is in contact with a peripheral part (bottom part outer peripheral part) of the lower frame 1b, and another part, in this case, a central part 82 is provided. A space (air layer) is formed between the lower frame 1b and the central portion 82 and is spaced from the lower frame 1b. For example, it is shaped like a shallow dish. A light source 7 is provided at a portion where the heat radiating member 8 is in contact with the lower frame 1 b of the frame 1. Further, the central portion 82 is provided with a through-hole 83 serving as a ventilation portion connecting the space between the lower frame 1b and the heat radiating member 8 and the outside. In the present embodiment, a plurality of the holes 83 are provided. The air in the space is ventilated between the lower frame 1b and the heat radiating member 8 through the hole 83, so that heat is radiated satisfactorily.

  The heat conductive sheets 9 and 10 are made of an adhesive sheet based on a material having good heat transfer efficiency, for example, a silicone elastomer or an acrylic elastomer, and the heat conductive sheet 9 transfers the heat of the circuit board 6 to the lower frame 1b. The heat conductive sheet 10 is a material that transfers heat of the lower frame 1b to the heat radiating member 8 well.

  In the display device configured as described above, heat generated by the light source 7 is transmitted to the circuit board 6, is transmitted from the circuit board 6 to the heat conductive sheet 9, and the lower frame 1b, and is radiated from the lower frame 1b. Further, the heat from the lower frame 1 b is transmitted to the heat radiating member 8 and is radiated from the heat radiating member 8. In addition, by providing the heat radiation member 8 with the hole 83 as a ventilation portion, the air in the space between the lower frame 1b and the heat radiation member 8 is warmed by heat radiation from the lower frame 1b and the heat radiation member 8. The warmed air is ventilated by the holes 83, and heat dissipation is performed well.

  Further, since the heat radiating member 8 has a flat plate shape, it can be provided on the back side of the light guide plate 4 of the light emitting device, and a plurality of conventional heat radiating wings are arranged to form a three-dimensional shape like a rectangular parallelepiped. Compared to the heat radiating member, a thin and compact heat radiating member can be obtained. In this embodiment, the heat radiating member 8 is set in a shape like a shallow dish as described above. However, the heat radiating member 8 may partially contact the frame 1 (lower frame 1a) and be separated from the space. What is necessary is just to be a waveform shape and a shape where an unevenness | corrugation continues.

  Further, the peripheral portion 81 of the heat radiating member 8 is in contact with the peripheral portion of the lower frame 1b, and the light source 7 is provided in the peripheral portion that is a contact portion with the heat radiating member 8 of the lower frame 1b. The heat can be transferred well to the heat radiating member 8. Furthermore, in the present embodiment, the light source 7 is provided only on one of the four side end faces 43. However, for example, when a plurality of light sources 7 are provided on each of the pair of opposing side end faces 43, each side end face is provided. It is not necessary to provide the heat dissipating members 8 of the plurality of light sources 7 for every 43, and an increase in the number of parts can be suppressed.

  Incidentally, as a second embodiment of the present invention, there are those shown in FIGS. In addition, the same code | symbol is attached | subjected to the same and equivalent part as the said embodiment, and the detailed description is abbreviate | omitted.

  In the present embodiment, the upper frame 1c is changed from the synthetic resin of the first embodiment to a metal. A heat radiating member 11 is provided on the side surface 1c1 of the upper frame 1c, particularly on the side surface 1c1 on the side where the light source 7 is provided. The heat radiating member 11 includes a base 111 that is in contact with the side surface 1c1 via the heat conductive sheet 12, and a plurality of heat radiating blades 112 that are extended from the base 111. The direction in which the heat radiating blade 112 extends is formed so as to extend in the same direction as the plate surface direction of the light guide plate 4 of the display device. By forming in this way, the heat dissipation member 11 is added while suppressing the thickness in the direction perpendicular to the irradiation surface 41 of the light guide plate 4 of the display device, thereby further radiating heat together with the lower frame 1b and the heat dissipation member 8. It can be carried out.

  Further, in the second embodiment, the thickness in the direction perpendicular to the irradiation surface 41 (plate surface) of the light guide plate 4 of the display device is suppressed, but as in the third embodiment shown in FIG. When suppressing the same horizontal area as the irradiation surface 41 (plate surface) of the light guide plate 4 of the display device, the irradiation surface 41 (plate surface) of the light guide plate 4 along the arrangement direction in which the light sources 7 of the lower frame 1b are provided. ) Is provided with a heat dissipating member 13 extending in the vertical direction. The heat dissipating member 13 has the same structure as the heat dissipating member 11 of the second embodiment, and a base 131 that is in contact with the back surface of the lower frame 1b (the lower surface in FIG. 9) via the heat conductive sheet 14, and the base A plurality of heat dissipating blades 132 extended from 131 are provided. The direction in which the heat radiating blades 132 are formed to extend in a direction perpendicular to the plate surface direction of the light guide plate 4 of the display device. By forming in this way, further heat dissipation can be performed together with the lower frame 1b by adding the heat dissipation member 11 while suppressing the same horizontal area as the irradiation surface 41 of the light guide plate 4 of the display device. In addition, in the configuration shown in FIG. 9, it is possible to improve the heat dissipation efficiency by adding the heat dissipation member 8 applied in the first and second embodiments.

The front view which shows the display apparatus by the 1st Embodiment of this invention. AA sectional drawing of FIG. FIG. 3 is an essential part cross-sectional view showing an enlarged vicinity of a light source in FIG. 2. BB sectional drawing of FIG. The front view of the board | substrate which mounted the light source of the embodiment. The rear view of the display apparatus of the embodiment. The front view which shows the display apparatus by the 2nd Embodiment of this invention. CC sectional drawing of FIG. Sectional drawing which shows the display apparatus by the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frame 1a, 1c Upper frame 1b Lower frame 1b1 Bending part 1b2 Locking piece 2 Display panel 3 Optical film 4 Light guide plate 5 Reflective film 6 Circuit board 7 Light source 8, 11, 13 Heat radiation member 9, 10, 12, 14 Thermal conduction Sheet (heat conductor)
41 Irradiation surface 42 Opposing surface 43 Side end surface 43a Light receiving surface 61 Cut (easy to bend)
71 Concave portion 72 Housing 73 Light emitting surface 81 Peripheral portion 82 Central portion 83 Hole (venting portion)

Claims (3)

A light source comprising a light emitting diode;
A light guide plate having a light receiving surface for introducing light from the light source and an irradiation surface for emitting light by light introduced from the light receiving surface;
A circuit board for supplying power to the light source;
In a light emitting device comprising a frame for housing the light source and the light guide plate,
A light emitting device comprising: a heat dissipating member that is in contact with a part of the frame and that forms a space with the frame. The light emitting device according to claim 1, further comprising a ventilation portion connected to the space portion. The light-emitting device according to claim 1, wherein the light source is provided in a part of the frame in contact with the heat dissipation member.

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