JP2009245882A - Backlight unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight unit capable of achieving a large screen of a display panel and reducing image display spot of the display panel resulting from the light-emission action of a light source unit. <P>SOLUTION: The backlight unit 1 includes a light guide 3 having a first main face 3A being a light output face and a second main face 3C opposed to the first main face 3A, a light source unit 4 which is arranged on the side face of the light guide 3 different from the first and the second main faces 3A, 3B, and a chassis 11 which supports the light guide 3 and is connected thermally to the light source unit 4. The chassis 11 includes a heating means which transmits heat of the light source unit 4 to a region 11C of the light guide 3 far from the light source unit 4 and heats the region of the second main face 3C of the light guide 3 far from the light source unit 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a backlight unit having a light guide, a light source unit disposed on a side surface of the light guide, and a chassis that holds the light guide and is thermally connected to the light source unit.

  A backlight unit such as an edge-light type liquid crystal backlight unit includes a light guide disposed on the back surface of the display panel and a light source unit disposed on a side surface of the light guide. The light emitted from the light source unit enters from the side surface of the light guide. The light guide body uniformly diffuses the light emitted from the light source unit, and outputs the diffused light evenly so as not to cause spots on the entire display surface. As a light source unit, a cold cathode discharge tube (CCFL), a light emitting diode (LED), an inorganic electroluminescence (EL), an organic EL, or the like is used, and a backlight unit incorporating these light source units has been developed. .

In addition, as this kind of backlight unit, it describes in the following patent document 1, for example.
Japanese Patent No. 2007-26916

  In the backlight unit in which the light source unit described above is incorporated, the following points have not been considered.

  In the backlight unit, when the light source unit is disposed to face the side surface of the light guide, the heat generated by the light emission operation of the light source unit is concentrated in the vicinity of the light source unit. Compared to the display panel area where the side area of the display panel corresponding to the area where the light source unit is arranged is far from the light source unit due to heat generated from the light source unit (for example, the center area when the light source units are arranged on both sides) Heated. For this reason, in the display panel, the characteristics of the thin film transistors (TFTs) and liquid crystals that form the pixels in the side region heated by the heat emitted from the light source unit change compared to the region far from the light source unit, and as a result Image display spots appear on the panel. In particular, in a backlight unit having a large display panel (having a large screen), the distance between the side region and the central region of the display panel in which the light source unit is disposed becomes large, and image display spots on the display panel are noticeable. Appear in

  The present invention has been made to solve the above problems. Accordingly, the present invention is to provide a backlight unit that can realize a large screen of the display panel and can reduce image display spots on the display panel due to the light emission operation of the light source unit.

  In order to solve the above-described problem, the feature according to the embodiment of the present invention is that a backlight unit includes a first main surface serving as a light output surface and a second main surface facing the first main surface. A light guide unit, a light source unit disposed on a side surface of the light guide different from the first and second main surfaces of the light guide, a light guide that is held and thermally connected to the light source unit A backlight unit comprising: a chassis, wherein the chassis transfers heat of the light source unit to a region of the light guide far from the light source unit to heat a region of the second main surface of the light guide far from the light source unit. Heating means is provided.

  Further, according to the embodiment of the present invention, in the backlight unit, a light guide having a first main surface serving as a light output surface and a second main surface facing the light output surface, and a light guide A pair of light source units disposed on a first side surface of the light guide different from the first and second main surfaces of the body and a second side surface facing the first side surface, and holding the light guide, A backlight unit comprising a chassis thermally connected to the light source unit, wherein the chassis transmits the heat of the light source unit to a central region of the light guide that is far from the pair of light source units. A heating means for heating the region is provided.

  Further, it is preferable that the light guide has a reflecting plate on the second main surface, and the chassis is in contact with the second main surface of the light guide.

  Furthermore, the light source unit is preferably constituted by a semiconductor light emitting device.

  Furthermore, it is preferable that a thermally connected liquid crystal is disposed on the first main surface.

  Furthermore, it is preferable that the heating means is constituted by a projecting region projecting on the second main surface of the light guide.

  According to the present invention, it is possible to provide a backlight unit that can realize a large display panel and can reduce image display unevenness of the display panel due to the light emission operation of the light source unit.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic and different from actual ones. In addition, there may be a case where the dimensional relationships and ratios are different between the drawings.

  Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is to arrange the components and the like as follows. Not specific. The technical idea of the present invention can be variously modified within the scope of the claims.

  In the embodiment of the present invention, an example in which the present invention is applied to an edge light type liquid crystal backlight unit having a large screen as a backlight unit will be described. In the following description, an example in which the present invention is applied to a thin liquid crystal backlight unit having a large 32-inch screen will be described. However, the present invention is not limited to this screen size, and a 32-inch screen. The present invention can also be applied to a thin liquid crystal backlight unit exceeding the size or a thin liquid crystal backlight unit having a screen size of less than 32 inches.

(Embodiment)
[Overall configuration of backlight unit]
As shown in FIGS. 1 and 2, a backlight unit 1 according to an embodiment of the present invention includes a display panel 2 and a light guide disposed to face one surface (back surface) 2 </ b> B of the display panel 2. A body 3, a chassis (back chassis) 11 in which the display panel 2 and the light guide 3 are disposed, and an inner surface of the chassis 11 facing the one side surface 3 </ b> B of the light guide 3. The first light source unit 4B for irradiating light on one side surface 3B of the light guide 3 and the other side surface 3T facing the one side surface 3B of the light guide 3 inside the chassis 11 A second light source unit 4T for irradiating the side surface 3T with light and a radiator 6 are provided.

[Configuration of light guide]
As shown in FIGS. 1 and 2, the light guide 3 has a surface normal direction of a light output surface (surface) 3 </ b> A facing the one surface 2 </ b> B of the display panel 2 with an appropriate distance, for example, 1 mm−2 mm. When viewed from the top (as viewed in plan), the flat plate material has a rectangular planar shape similar to the planar shape of the display panel 2. Further, the planar size of the light guide 3 is slightly larger than the planar size of the display panel 2. For example, in the case of 32 inches, the light guide 3 having a size of 420 mm to 440 mm in length, 710 mm to 730 mm in width, and 8.0 mm to 13.0 mm in thickness is used.

  The light guide 3 receives the light emitted from the first light source unit 4B from one side surface 3B and the light emitted from the second light source unit 4T from the other side surface 3T. Is uniformly diffused, and the light uniformly diffused from the light output surface 3A is output to the display panel 2. The light guide 3 is thus light transmissive, excellent in heat resistance, and low in reflectance with respect to the light emitted from the first and second light source units 4B and 4T, such as an acrylic resin. Can be used practically.

[Configuration of light source unit]
Each of the first light source unit 4B and the second light source unit 4T includes a semiconductor light emitting element (light emitting diode) 42. That is, as shown in FIG. 1, the first light source unit 4B is a base of the semiconductor light emitting element 42, transfers heat when the semiconductor light emitting element 42 emits light, and a substrate 41 made of an insulating material, and a substrate The semiconductor light-emitting element 42 on 41 is comprised. In the present embodiment, several to tens of semiconductor light emitting elements 42 are mounted on one substrate 41 to constitute the first light source unit 4B. Similar to the first light source unit 4B, the second light source unit 4T includes a substrate 41 and the same number of semiconductor light emitting elements 42 as the first light source units 4B.

[Heat radiator]
As shown in FIG. 1, the radiator 6 is attached to the back surface of the substrate 41 of the first and second light source units 4B and 4T, and the radiator 6 is between the first and second light source units 4B and 4T. Heat transfer is possible. The radiator 6 extends to a non-projecting region 11NC, which will be described later, of the chassis 11. At least a part of the radiator 6 is thermally connected to the bottom surface of the chassis 11, and the first and Heat can be transferred between the second light source units 4 </ b> B and 4 </ b> T and the bottom surface of the chassis 11. That is, the first and second light source units 4 </ b> B and 4 </ b> T and the chassis 11 are thermally connected via the radiator 6.

  As shown in FIG. 1, the cross-sectional shape of the heat radiating body 6 includes a portion parallel to the back surface of the substrate 41 of the first and second light source units 4 </ b> B and 4 </ b> T and a non-projecting region 11 </ b> NC (described later) of the chassis 11 orthogonal thereto. It is preferable that it is L-shape which has a parallel part. The heat radiator 6 efficiently transfers heat generated by the light emission operations of the first and second light source units 4B and 4T to the chassis 11.

  In the present embodiment, the radiator 6 can be made of a material that has excellent thermal conductivity and can be easily molded. For example, a plate-like copper alloy can be used practically for the heat radiator 6. The space between the radiator 6 and the back surfaces of the substrates 41 of the first and second light source units 4B and 4T is mechanically and thermally using, for example, an adhesive tape having insulating properties, thermal conductivity, and adhesiveness. The chassis 11 and the first and second light source units 4B and 4T may be thermally connected by an elastic member such as a leaf spring.

[Case configuration]
As shown in FIGS. 1 to 3, in the backlight unit 1, a casing of the entire apparatus is constructed by a bezel 10 disposed on the display panel 2 side and a chassis 11 disposed on the light guide 3 side. The display panel 2, the light guide 3, the first light source unit 4 </ b> B, the second light source unit 4 </ b> T, and the heat radiating body 6 are disposed at least inside the housing constructed by the bezel 10 and the chassis 11. Yes. In the present embodiment, the bezel 10 is made of a metal material such as a resin material or aluminum that can be easily molded. Further, the chassis 11 is superior in thermal conductivity to the light guide 3 and can be easily molded, and is a material that is excellent in mechanical strength and inexpensive, such as aluminum (Al) or an alloy thereof. It is made of a metal material.

  The chassis 11 includes a protruding region 11C that contacts the central region of the back surface 3C facing the light output surface 3A of the light guide 3 and a non-projecting region 11NC that does not contact the peripheral region of the back surface 3C of the light guide 3. .

  In the present embodiment, the projecting region 11C projects on the back surface 3C side of the light guide 3 more than the non-projected region 11NC, so that heat is transferred from the projecting region 11C of the chassis 11 to the light guide 3 well. When the bottom surface of the chassis 11 where the projecting region 11C and the non-projecting region 11NC are disposed is viewed from the normal direction of the surface, the shape of the projecting region 11C is opposite to the first and second light source units 4B and 4T. The light guide 3 has a rectangular shape elongated in a direction parallel to one side 3B and the other side 3T (longitudinal direction of the light guide 3). Note that the protruding region 11C of the chassis 11 does not necessarily contact the back surface 3C of the light guide 3, and the heat transfer is good, for example, the protruding region 11C is closer to the back surface 3C of the light guide 3 than the protruding region 11NC. It is only necessary to heat the region of the light guide 3 that faces the protruding region 11C.

  In the protruding area 11C, the heat generated by the light emission operation of the first light source unit 4B, as shown by an arrow h1 in FIG. The light is transmitted to the projecting region 11C through the non-projecting region 11NC of the chassis 11 with the one light source unit 4B. Further, in the protruding region 11C, heat generated by the light emission operation of the second light source unit 4T is projected from the non-projecting region 11NC of the chassis 11 with which the radiator 6 is in contact, as indicated by an arrow h2 in FIG. Is transmitted to the projecting region 11C through the non-projecting region 11NC of the chassis 11 between the first light source unit 4T and the second light source unit 4T. The transmitted heat is transmitted from the protruding region 11C to the central region of the display panel 2 through the light guide 3, and the temperature of the region corresponding to the protruding region 11C of the display panel 2 rises. In addition, the area near the first light source unit 4B of the display panel 2 is heated by heat generated by the light emission operation of the first light source unit 4B, and the area near the second light source unit 4T of the display panel 2 is the second area. The temperature rises due to heat generated by the light emission operation of the light source unit 4T. That is, variation in temperature distribution in the surface of the display panel 2 can be reduced. Therefore, image display spots on the display panel 2 can be reduced.

  As described above, in the backlight unit 1 according to the present embodiment configured as described above, the chassis 11 includes the projecting region 10C and the non-projecting region 11NC, and the first light source unit 4B and the second light source. Since the heat accompanying the light emission operation of the unit 4T is transmitted to the central region of the display panel 2 through each of the non-projecting region 11NC and the projecting region 11C of the chassis 11, the temperature distribution of the entire display panel 2 can be made uniform. As a result, image display spots on the liquid crystal display panel 2 can be reduced, and as a result, a large screen of the display panel 2 can be realized.

[Modification: Chassis Modification]
In the backlight unit 1 according to the modification of the present embodiment, the planar shape of the protruding region 11C of the chassis 11 that contacts the central region of the back surface 3C facing the light output surface 3A of the light guide 3 is shown in FIG. It has a circular shape. A plurality of protruding regions 11C are arranged at regular intervals in a direction parallel to the side surface 3B and the side surface 3T of the light guide 3. A non-projecting region 11NC is disposed between the projecting region 10C of the chassis 11 and the side surface on the first light source unit 4B side and between the projecting region 10C and the side surface on the second light source unit 4T side.

  Since the backlight unit 1 according to this modification includes the protruding region 11C, the same effect as that obtained by the backlight unit 1 according to the present embodiment described above can be obtained.

  Here, the planar shape of the projecting region 11C is formed in a circular shape, but any one of an elliptical shape, a triangular shape, a rectangular shape, or a polygonal shape of pentagon or more may be adopted.

  In the central region of the back surface 3C facing the light output surface 3A of the light guide 3, a protruding region 11C composed of a plurality of rows may be disposed instead of one row as shown in FIG.

(Other embodiments)
As mentioned above, although this invention was described by one Embodiment, the description and drawing which make a part of this indication do not limit this invention. The present invention can be applied to various alternative embodiments, examples, and operational technologies. For example, in the above-described embodiment, an example in which the backlight unit 1 is applied to a liquid crystal backlight unit has been described, but the present invention is not limited to this. Specifically, the present invention can be applied to a liquid crystal display monitor connected to, for example, a personal computer as the backlight unit 1.

  Further, in the backlight unit 1 according to the above-described embodiment, light emitting diodes are used for the first light source unit 4B and the second light source unit 4T. A cold cathode discharge tube may be used. However, since the light emitting diode generates heat more easily than the discharge tube, the effect of the present invention can be easily obtained.

  Further, the light guide 3 is an inclusion for transferring the heat of the chassis 11 to the display panel 2, and the light guide 3 may not be provided, and the light guide 3 and the chassis 11 are not in contact with each other. Also good. Furthermore, a reflector that can transfer the heat of the chassis 11 to the light guide 3 between the light guide 3 and the chassis 11 may be sandwiched between the light guide 3 and the chassis 11.

  Further, when both the pair of light source units 4B and 4T are not necessary, the light source unit may be disposed only on one side. In this case, the thickness of the light guide 3 in the vicinity of the light source unit is formed to be thicker than the thickness of the light guide far from the light source unit. In this case as well, a region far from the light source unit becomes the protruding region 11C. Thus, it is set as the structure which adjoins to the light guide 3. The light source unit may also be disposed on the right side surface (right side surface in FIG. 2) 11R of the chassis 11 in FIG. 2 and the right side surface (left side surface in FIG. 2) 11L of the chassis 11. In this case, the protruding region 11C away from the light source unit is a central region of the light guide 3, and for example, the protruding region 11C is formed in a circular shape.

  Furthermore, the present invention can basically be applied to a backlight unit (backlight device) or a backlight unit having an illumination unit (illumination device). For example, the backlight unit is mounted on the back of a photo or poster. It can be applied to a viewer (signboard with a backlight unit).

It is sectional drawing of the backlight unit which concerns on one embodiment of this invention. It is a top view of the backlight unit concerning one embodiment. It is a schematic perspective view of the chassis of the backlight unit according to one embodiment. It is a schematic perspective view of the chassis of the backlight unit which concerns on the modification of one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Backlight unit 2 ... Display panel 3 ... Light guide 3B ... One side 3T ... Other side 3A ... Light output surface 4B ... 1st light source unit 4T ... 2nd light source unit 6 ... Radiator 41 ... Substrate 42 ... Light emitting diode 10 ... Bezel 11 ... Chassis 11C ... Protruding region 11NC ... Non-projecting region

Claims (6)

A light guide having a first main surface to be a light output surface and a second main surface opposite to the first main surface;
A light source unit disposed on a side surface of the light guide different from the first and second main surfaces of the light guide;
In a backlight unit comprising the chassis that holds the light guide and is thermally connected to the light source unit,
The chassis includes a heating unit that transfers heat of the light source unit to a region of the light guide that is far from the light source unit and heats a region of the second main surface of the light guide that is far from the light source unit. Backlight unit characterized by that. A light guide having a first main surface serving as a light output surface and a second main surface facing the light output surface;
A pair of light source units disposed on a first side surface of the light guide body different from the first and second main surfaces of the light guide body and on a second side surface facing the first side surface;
In a backlight unit comprising the chassis that holds the light guide and is thermally connected to the light source unit,
The chassis includes a heating unit that transfers heat of the light source unit to a central region of the light guide that is far from the pair of light source units to heat the central region of the light guide. unit.   The said light guide is provided with the reflecting plate in the said 2nd main surface, The said chassis is contact | abutted with the said 2nd main surface of the said light guide. Backlight unit.   The backlight unit according to any one of claims 1 to 3, wherein the light source unit is configured by a semiconductor light emitting device.   5. The backlight unit according to claim 1, wherein a thermally connected liquid crystal is disposed on the first main surface.   The backlight unit according to any one of claims 1 to 5, wherein the heating unit is configured by a projecting region projecting on the second main surface of the light guide.

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