JP2010238420A - Backlight unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight unit in which uniformity of luminance and thinness of the unit are attained by enabling diffusion of light to the whole region by using one LED in the region. <P>SOLUTION: The backlight unit 100 is used for a liquid crystal panel in which the liquid crystal panel is divided into a plurality of divided regions and is controlled for every divided region. Each divided region has an LED 12 arranged right below the display face so that a light emitting face may be right on the top, a reflector 14 of reverse cone shape with the vertex facing down arranged right above the light emitting face of the LED 12, and a diffusion plate 16 having scattering characteristics arranged at the opposed position on the opposite side to the LED 12 of the reflector 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a backlight unit using an LED (light emitting diode) as a light source.

In the conventional backlight unit, a light guide groove portion for guiding light while diffusing in all directions around a light receiving concave portion (prism) for efficiently entering light emitted from an LED is formed on the back surface of the light guide plate, and the unevenness is reduced. There is no illumination. (For example, Patent Document 1)
Further, by providing a partition wall between the partially driven light source regions, the backlight unit is effectively matched with the liquid crystal panel by controlling the light distribution on the upper surface of the backlight unit for each optical region. (For example, Patent Document 2)

JP 2004-319340 A JP 2007-286627 A

  In the technique of Patent Document 1 described above, since the LEDs are simply arranged immediately below, it is necessary to increase the thickness of the internal space in order to improve the uniformity of the luminance of the display surface, so it is difficult to reduce the thickness. It becomes. Further, when the size of one area is increased, it is necessary to increase the number of LEDs, resulting in higher cost.

  Further, in the technique of Patent Document 2, since the LEDs are simply arranged immediately below the liquid crystal panel, it is necessary to increase the thickness of the internal space in order to make the luminance distribution on the display surface uniform. For this reason, it not only becomes a barrier to thinning the backlight, and thus thinning the liquid crystal panel, but if the size of one region is increased, it is necessary to increase the number of LEDs in one region, resulting in high cost. There is a problem.

  An object of the present invention is to provide a backlight unit capable of contributing to uniform brightness and thinning of the unit by diffusing light over the entire area with one LED per area. .

  In order to solve the above-described problems, the backlight unit of the present invention has a diffusing means applied to a rectangular frame having a bottomed portion, and a light emitting surface is directly above the center of the bottomed portion. An attached LED and a cone formed on the light emitting surface by a light-transmitting material in which a flat portion formed at the tip of an inverted conical shape having a concave portion formed at the center of the base is opposed to each other, leaving the flat portion. A light guide reflector having a first reflection surface formed in a portion and a second reflection surface formed in the recess; a first diffuser plate disposed at a base of the light guide reflector; A second diffusing plate disposed in an open portion of the frame opposite to the bottom, and the light emitted by the LED is transmitted from the planar portion of the light guide reflector to the first and second The light is guided through the reflection surface and diffused by the first diffusion plate, and the Together is irradiated is diffused by the second diffusion plate, characterized in that said via diffusion means is irradiated through the second diffusion plate.

  Further, the backlight unit of the present invention includes a diffusing means applied to a rectangular frame having a bottomed portion, an LED attached to the center of the bottomed portion so that a light emitting surface is directly above, A convex reflecting spherical surface facing the light emitting surface, a plano-convex reflecting plate having the opposite surface of the reflecting spherical surface as a plane, and a diffusion wall that crosses the central portion of the light emitting surface and is attached to the frame And a diffusing plate disposed in an open portion of the frame opposite the bottomed portion, and the light emitted from the LED is reflected directly or by the reflecting spherical surface, and then the diffusing means, It is diffused by a diffusion wall and irradiated through the diffusion plate.

  According to the present invention, the light emitted from one LED per region is diffused over the entire region, so that it is possible to achieve uniform brightness and thin units.

It is a notional exploded perspective view for explaining one embodiment about a backlight unit of this invention. It is a front view of the principal part of FIG. FIG. 2 is a perspective view of a region of FIG. 1. FIG. 4 is a front view of FIG. 3. FIG. 4 is a sectional view taken along line Ia-Ib in FIG. 3. It is sectional drawing which expands and shows the principal part of FIG. It is explanatory drawing for demonstrating the luminance distribution in 1 area | region of this invention. It is explanatory drawing for demonstrating the luminance distribution in the whole system of this invention. It is a conceptual exploded perspective view for demonstrating other embodiment regarding the backlight unit of this invention. FIG. 10 is a perspective view of one area portion of FIG. 9. 10 is a front view of the main part. It is the IIa-IIb sectional view taken on the line of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  1 to 6 are diagrams for explaining an embodiment of the backlight unit according to the present invention. FIG. 1 is a conceptual exploded perspective view, FIG. 2 is a front view of the main part of FIG. 1, and FIG. 4 is a front view of FIG. 3, FIG. 5 is a sectional view taken along line Ia-Ib of FIG. 3, and FIG. 6 is an enlarged cross-sectional view of the main part of FIG.

  As shown in FIGS. 1 and 2, the backlight unit 100 of the present invention is configured, for example, by adhering three light source units 11 in the vertical direction and three in the horizontal direction. The light source unit 11 has a bottom portion 111 made of, for example, white resin, and the LED 12 with the light emitting surface 121 facing upward in the center of the bottom portion 111 of the rectangular frame 112 that is open at a position facing the bottom portion 111. Is fixed on the insulating substrate 13 and, as shown in FIGS. 3 and 4, is an inverted cone with the apex facing downward directly above the center of the light emitting surface 121 and has a V-shaped cross section. A light guide reflector 14 is disposed. For example, a diffusion sheet 113 having a reflectance of about 95% is attached to the inner surface of the frame body 112.

  As shown in FIGS. 5 and 6, the light guide reflector 14 is made of, for example, an acrylic resin having good light transmittance, and has a flat portion 141 at the top, and an inverted conical recess 143 of the base portion 142. Is formed. A first reflecting surface 144 is formed on the surface of the inverted cone leaving the flat surface portion 141 of the light guide reflector 14, and a reflecting surface 145 is formed in the recess 143 by, for example, aluminum vapor deposition.

  A diffusion plate 15 is disposed on the base 142 of the light guide reflector 14, and diffuses and emits light emitted from the light guide reflector 14. The diffusion plate 16 is disposed so as to be spaced from the diffusion plate 15 and close the open portion of the light source unit 11.

  The outer periphery of the light guide reflector 14 is attached to the insulating substrate 13 via the support 17. The support body 17 has, for example, four columnar shapes so that the light emitted from the LED 12 is emitted to the outside, and is designed with a thickness and a positional relationship such that light is not shielded as much as possible.

  The planar portion 141 of the light guide reflector 14 has a relationship with the portion facing the light emitting surface 121 of the LED 12 so that the light emitted through the light guide reflector 14, the reflection surface 144 of the light guide reflector 14, and the direct emission. The light distribution is designed to be uniform when the light to be synthesized is synthesized by the diffusion plate 16.

  One light source unit 11 constitutes one area, and these constitute a backlight unit 100 for one screen by combining 3 × 3 areas as described above. The diffusion plate 16 also serves as the 3 × 3 light source units 11. The height of the frame body 112 located outside each light source unit 11 is increased, and the space between the frame body 112 located inside as shown in FIG. By interfering with each other, the brightness between the junctions of the light source units 11 is made uniform.

  As shown in FIG. 6, among the light emitted from the light emitting surface 12 of the LED 12, the light irradiated on the flat surface portion 141 reaches the base portion 142 while reflecting the light guide reflector 14 inside the reflecting surfaces 144 and 145. To do. The light so far is diffused and emitted by the diffusion plate 15. The light emitted from the diffusion plate 15 reaches the diffusion plate 16, where it is further diffused and irradiated.

  In addition, light emitted from the light emitting surface 12 of the LED 12 except for the flat surface portion 141 is reflected by the reflecting surface 144 of the light guide reflector 14 and directly irradiated by the light. The light reaches the diffusion plate 16 while being diffused by the diffusion sheet 113 formed on the bottomed portion 111 and the frame body 112, where it is further diffused and irradiated.

  The light reaching the diffusion plate 16 while being diffused by the diffusion sheet 113 and the light reaching the diffusion plate 16 via the diffusion plate 15 are combined to irradiate the light from the light source unit 11, in other words, the backlight of the backlight unit 100. Irradiate as In this case, even when the distance between the LED 12 and the diffusing plate 16 is short, the light of the LED 12 is diffused, so that the luminance distribution in the diffusing plate 16 can be made uniform.

  7 and 8 are for explaining the comparison between the present invention and the conventional luminance distribution. FIG. 7 shows the luminance distribution when traversing the center of one light source unit 11, and FIG. The luminance distribution when the center of the three light source units 11 across the backlight unit 100 is crossed is shown.

  As shown in FIG. 7 and FIG. 8, in the present invention indicated by the solid line, the brightness at the position facing the LED is high and the surrounding area is low, as compared with the conventional technique indicated by the broken line, It was found that the luminance distribution of the entire backlight unit can be made uniform with little difference in luminance at the periphery.

  In this way, since the display area is divided, it is possible to perform light adjustment and color adjustment control so that the LEDs corresponding to the individual areas are synchronized with the liquid crystal panel, and high contrast of the image is achieved. Power can be saved.

  In this embodiment, even when the distance between the LED 12 and the diffusing plate 16 is short, the light from the LED 12 irradiated to the diffusing plate 16 is diffused, so that the luminance distribution in the diffusing plate 16 can be made uniform. Thus, the backlight unit 100 can be reduced in thickness, and thus the backlight-type liquid crystal panel can be reduced in thickness. Furthermore, light control and color control can be performed by synchronizing LEDs corresponding to individual regions with the liquid crystal panel, thereby enabling high-contrast video and power saving.

  The reflector 13 has an inverted conical shape as an example, but may be an inverted quadrangular prism or a rotating polyhedron.

  9 to 12 are conceptual exploded perspective views, FIG. 10 is a perspective view of a single main part of FIG. 9, and FIG. 11 is a schematic exploded perspective view for explaining another embodiment of the backlight unit of the present invention. FIG. 10 is a front view of FIG. 10, and FIG. 12 is a sectional view taken along line IIa-IIb of FIG. In addition, the same code | symbol is attached | subjected to the part of the same function as above-mentioned embodiment, and a different part is demonstrated here.

  In this embodiment, a convex reflecting spherical surface 911 is provided on the surface facing the light emitting surface 121 of the LED 12, a plano-convex reflecting plate 91 having a flat rear surface is disposed, and a cross shape is formed in the frame 112 of the light source unit 11. For example, a diffusion wall 92 made of resin and having a reflectivity of about 95% is disposed. The diffusion wall 92 looks like the frame 112 is divided into four.

  A diffusion diffusion sheet 113 is formed on at least the vertical surface of the diffusion wall 92. The diffusion wall 92 is integrally formed. The crossing portion of the cross-shaped diffusion wall 92 is arranged to be an intermediate portion of the frame body 112, and a taper 921 that gradually separates from the diffusion plate 16 is formed in the crossing portion. As shown in FIG. 12, the height h of the diffusion wall 92 and the height H from the bottomed portion 111 of the frame body 112 have a relationship of h <H.

  Of the light emitted from the light emitting surface 12 of the LED 12, the light reflected by the reflecting spherical surface 911 of the plano-convex reflecting plate 91 is diffused by the bottomed portion 111 and further diffused by the frame body 112 and the diffusion wall 92 and diffused. 16 is diffused and irradiated outside the light source unit 11.

  Incidentally, a taper 921 is formed on the diffusion wall 92 at a portion of the reflecting plate 91 facing the opposite surface of the plano-convex reflecting plate 91. The light diffused by the bottomed portion 111, the frame body 112, and the diffusion wall 92 reaches the diffusion plate 16 so as to cross over the taper 921 and is irradiated from the diffusion plate 16.

  Further, since the height h of the diffusion wall 92 and the height H of the frame body 112 are in a relationship of h <H, they are diffused through a gap between the lower side of the frame body 112 and the bottomed portion 111. The light reaches the diffusion plate 16 in a crossover manner and is irradiated from the diffusion plate 16.

  In this way, the diffuser plate 16 facing the opposite surface of the plano-convex reflector 91 and the other diffuser plates 16 are uniformly irradiated with diffused light from all directions, so that the luminance of the entire diffuser plate 16 is increased. The distribution can be made uniform.

  This is because when the positional relationship between the LED 12 and the diffusing plate 16 is close, the luminance distribution between the diffusing plate 16 directly below the LED 12 and other surfaces can be made uniform, and the backlight unit 100 can be made thinner. This can contribute to thinning of the backlight type liquid crystal panel.

  Also in this embodiment, as in FIG. 8, it was found that the luminance distribution of the entire backlight unit can be made uniform with little difference in luminance between the position facing the LED and its periphery.

  In this embodiment, the light generated by the LED over a wide area can be obtained by placing a flat surface on the top and a plano-convex reflector on the bottom just above one LED with the light emitting surface facing upward in the center of one region. By arranging the diffusion wall that can be diffused and the area is divided into a plurality of areas, it is possible to realize a uniform luminance distribution up to the periphery of the area.

  In this case as well, since the display area is divided, it is possible to perform light control and color control that synchronize the LEDs corresponding to the individual areas with the liquid crystal panel, thereby increasing the contrast of the image and saving power. Can be made.

  In this embodiment, the single light source unit 11 is divided into four by the cross-shaped diffusion wall 92, but the straight diffusion wall 92 may be used and the single light source unit 11 may be divided into two. It is also conceivable to increase the number of division walls 92 by increasing the number of diffusion walls 92. Even in this case, a taper 921 is formed in a portion of the back surface of the plano-convex reflector 91 facing the diffuser plate 16, and the diffuser wall 92 is arranged so as to cross the central portion of the plano-convex reflector 91.

  Further, the luminance distribution can be obtained by applying a means having a scattering property with a high reflectivity such as a diffusion sheet or diffusion coating to the flat surface on the opposite side of the reflection spherical surface 911 of the plano-convex reflection plate 91 facing the diffusion plate 16. Can be improved.

  The present invention is not limited to the above-described embodiment, and the diffusion sheet 113 attached to the bottomed portion 111 and the frame body 112 may be by painting. Moreover, you may diffuse by forming the formation surface of the bottomed part 111 and the frame 112 roughly. In short, any configuration of diffusing means having high reflectivity and scattering characteristics may be used.

  Furthermore, although the case where the number of light source units 11 is 3 × 3 is 9 as an example, the number of light source units 11 is not limited to this and may be more or less. By making the vertical and horizontal sizes of the light source unit 11 also based on the aspect ratio of the liquid crystal panel, the compatibility between the backlight 100 and the liquid crystal panel becomes good.

100 Backlight Unit 11 Light Source Unit 111 Bottomed Part 112 Frame 113 Diffusion Sheet 12 LED
121 Light Emitting Surface 14 Light Guide Reflector 141 Flat Portion 142 Base 143 Recesses 144 and 145 Reflecting Surfaces 15 and 16 Diffusion Plate 17 Support 91 Plano-convex Reflection Plate 911 Reflecting Spherical Surface 92 Diffusion Wall 921 Taper

Claims (8)

Diffusion means applied to a rectangular frame having a bottomed portion;
An LED attached to the center of the bottomed portion so that the light emitting surface is directly above;
The light emitting surface is formed of a light-transmitting material having a flat portion formed at the tip of an inverted conical shape having a concave portion formed at the center of the base, and is formed in a conical portion that leaves the flat portion. A light guide reflector having a first reflective surface and a second reflective surface formed in the recess;
A first diffuser disposed at the base of the light guide reflector;
A second diffusion plate disposed in an open portion of the frame body facing the bottomed portion, and
The light emitted from the LED is guided from the planar portion of the light guide reflector through the first and second reflective surfaces and diffused by the first diffusion plate, and further the second A backlight unit characterized by diffusing and irradiating with a diffusion plate and irradiating through the second diffusion plate through the diffusion means. Diffusion means applied to a rectangular frame having a bottomed portion;
An LED attached to the center of the bottomed portion so that the light emitting surface is directly above;
A plano-convex reflector having a convex reflecting sphere on the surface facing the light emitting surface, and a surface opposite to the reflecting sphere;
A diffusion wall that crosses the central portion of the light emitting surface and is attached to the frame;
A diffusion plate disposed in an open part of the frame opposite to the bottomed part,
The backlight unit is characterized in that the light emitted from the LED is reflected directly or by the reflecting spherical surface, and then is diffused by the diffusing means and the diffusing wall and irradiated through the diffusing plate.   The backlight unit according to claim 1, wherein the diffusing unit has a diffusion sheet attached thereto.   The backlight unit according to claim 1, wherein the diffusing unit is formed by painting.   3. The backlight unit according to claim 1, wherein the diffusing unit has a rough forming surface.   The backlight unit according to claim 2, wherein a flat surface portion of the plano-convex reflection plate facing the diffusion plate is a reflection surface having diffusion characteristics.   3. The backlight unit according to claim 2, wherein at the position of the diffusing wall facing the plano-convex reflector, the backlight unit has a tapered shape with a gradually decreasing height toward the center of the plano-convex reflector.   The backlight unit according to claim 2, wherein the height h of the diffusion wall has a relationship of h <H with respect to the height H of the frame body from the bottomed portion.

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