JP2006278077A - Backlight device and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device and a liquid crystal display capable of easily improving positioning accuracy of a reflecting plate against a substrate and maintaining a constant distance at all times between a semiconductor light-emitting element and a photoelectric member, in a simple structure. <P>SOLUTION: The backlight device is provided with a plane light source made by arranging a plurality of LED elements 1 on the substrate 2, a reflective plate 3 installed on the substrate 2 so as to fill spaces between the LED elements 1, and a diffusing plate located at a light-irradiation side of the plane light source and the reflecting plate 3. Protruded parts 2a protruded rather toward a side of the diffusing plate 5 than the LED elements 1 are provided on the substrate 2, and insertion holes 3a are provided at the reflecting plate 3 for the protruded parts 2a to be inserted into. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a direct type backlight device using a semiconductor light emitting element such as a light emitting diode (LED) or a laser diode, and a liquid crystal display device using the same.

  Currently, as a backlight device incorporated in a large-screen liquid crystal display device, a direct-type backlight device in which a plurality of cold cathode fluorescent lamps (CCFLs) are arranged directly below a liquid crystal display panel is used. . However, cold-cathode tubes have problems such as the need for a high voltage for the drive inverter, the presence of mercury, and the small color reproduction range. Development of a type backlight device is underway.

  For example, Japanese Unexamined Patent Application Publication No. 2004-319458 (Patent Document 1) discloses a backlight device in which a plurality of light emitting elements corresponding to a plurality of colors including red, green, and blue, that is, a plurality of LEDs capable of emitting primary colors, are arranged to form a surface light source. Therefore, a liquid crystal display device capable of achieving high brightness even on a large screen has been proposed. This will be described below with reference to FIGS. Here, FIG. 5A shows a configuration example of a conventional backlight device, (a) a plan view of the main part, (b) an enlarged side sectional view of the main part, and FIG. 6 shows another configuration example of the conventional backlight device. (A) principal part top view, (b) principal part enlarged side sectional view, FIG. 7: (a) side sectional view which shows the other structural example of the conventional backlight apparatus, (b) principal part top view.

  As shown in FIG. 5, a conventional direct-type backlight device using LEDs includes a linear light source in which LED elements 1 are continuously arranged and a material such as an aluminum material, and the LED element 1 is installed. In addition, a substrate 2 that also has a function of a heat sink, and a reflector 3 that is provided on the substrate 2 so as to fill (cover) the LED element 1 with a through hole into which the LED element 1 is fitted. I have. In addition, as a material of the reflecting plate 3, an aluminum plate reflecting plate, white polyester (which is foamed and mixed with a scattering material), silver-deposited polyester, or the like can be used.

  In this example, the reflector 3 is installed on the substrate 2 to avoid the metal-embedded PCB 4 on which the circuit or wiring for driving the LED element 1 is disposed, so the surface area coverage of the reflector 3 is improved. There is a problem that it is difficult to cause brightness unevenness and color unevenness. Therefore, as a direct type backlight device using other conventional LEDs, as shown in FIGS. 6 and 7, a through hole is formed so that the light emitting portion of the LED element 1 is fitted, and the portion other than the LED light emitting portion is formed. The structure which provided the reflecting plate 13 arrange | positioned so that (metal embedding PCB4) may be covered is proposed.

  An optical member such as a diffusing plate 5 is provided on the light emitting side of the surface light source and the reflecting plates 3 and 13 shown in FIGS. As the diffusing plate 5, a transparent acrylic resin plate provided with irregularities for scattering light or a transparent acrylic resin containing particles that scatter light is used as a plate.

  In addition, a liquid crystal display panel is installed in front of the diffusion plate 5 (upper side in FIG. 7A) with a predetermined optical sheet such as a prism sheet (light condensing sheet) interposed therebetween, thereby displaying a desired image. Can be done.

Furthermore, in the above-mentioned Patent Document 1, there are three LED elements corresponding to the three primary colors of light in addition to the linear light sources in which the LED elements 1 are arranged in series are arranged in a predetermined order to constitute a surface light source. Are described in which light emitting element groups arranged in proximity to the apex of a triangle are arranged in a matrix to constitute a surface light source.
JP 2004-319458 A

  By the way, when external pressure is applied to the sealing resin (silicon resin or the like) on the light emitting surface of the LED element 1 or the light emitting portion, the reliability of the LED element 1 is significantly impaired. The direct type backlight device used has a configuration in which the reflectors 3 and 13 are installed on the substrate 2 so as to fill the space between the LED elements 1 in order to suppress the occurrence of luminance unevenness and color unevenness. In the assembly process or the like, if the mounting positions of the reflecting plates 3 and 13 with respect to the substrate 2 are slightly shifted, the reflecting plates 3 and 13 damage the light emitting surface of the LED element 1 and the sealing resin on the upper surface of the light emitting portion. There has been a problem of causing uneven brightness and uneven color.

  In addition, the LED element generally has a light distribution characteristic in which a large amount of heat is generated due to light emission driving, and the directivity is strong (the radiation angle is small). Therefore, when the temperature rises due to the heat generated by the LED element 1, the diffusion plate 5 bends (warps), and the distance between the LED element 1 and the diffusion plate 5 changes. As a result, luminance unevenness and color unevenness occur. There was a problem of incurring outbreaks. Furthermore, since the light emitting characteristics of the LED element itself change depending on the ambient temperature, it is indispensable to take measures to dissipate heat in order to prevent luminance unevenness, color unevenness, and color balance deterioration.

  It is generally known that a direct-type backlight device using a cold cathode fluorescent lamp (CCFL) is provided with a projection on the reflector to prevent the diffusion plate from bending (warping). However, in this case, even if the distance between the reflector and the diffuser can be kept constant, the distance between the light source and the diffuser can be kept constant if the reflector is warped or the light source is bent. There is a problem in that brightness unevenness is caused.

  Here, Japanese Patent Application Laid-Open No. 2004-327449 discloses a multi-tube type in which a plurality of lamp holding portions and protrusions are integrally molded in order to keep the distance between the cold cathode fluorescent lamp (CCFL) and the diffusion plate constant. Although a lamp holder has been proposed, it cannot be applied to a direct type backlight device using a semiconductor light emitting element such as an LED as it is.

  The present invention has been made in view of the above problems, and easily improves the positioning accuracy of the reflector with respect to the substrate with a simple configuration, and always keeps the distance between the semiconductor light emitting element and the optical member constant. The present invention provides a backlight device and a liquid crystal display device that can be used.

  According to a first aspect of the present application, a surface light source in which a plurality of semiconductor light emitting elements are arranged on a substrate, a reflection plate installed on the substrate so as to fill a space between the semiconductor light emitting elements, and the surface light source And an optical member positioned on the light emitting side of the reflecting plate, wherein a protrusion projecting toward the optical member from the semiconductor light emitting element is provided on the substrate, and the reflecting plate Further, an insertion hole through which the protruding portion is inserted is provided.

  The second invention of the present application is characterized in that the projection is integrally formed with the substrate.

  The third invention of the present application is characterized in that the protrusion is formed of a heat radiating material having good thermal conductivity.

  A fourth invention of the present application is characterized in that the protrusion is formed of a white highly reflective material.

  According to a fifth invention of the present application, the surface light source is a linear light source in which the semiconductor light emitting elements are arranged in series, and is arranged in a predetermined order, and the protrusion is an intermediate position between adjacent linear light sources. It is provided in.

  According to a sixth invention of the present application, the surface light source is a linear light source in which the semiconductor light emitting elements are arranged in series, and is arranged in a predetermined order, and the protrusion is provided between the semiconductor light emitting elements in each linear light source. It is provided in.

  A seventh invention of the present application includes the above-described backlight device and a liquid crystal display panel for displaying an image.

  According to the backlight device and the liquid crystal display device of the present invention, the projection position provided on the substrate is inserted into the insertion hole provided in the reflection plate, thereby easily improving the mounting position accuracy of the reflection plate with respect to the substrate. Therefore, it is possible to prevent unevenness in luminance and color due to damage to the light emitting surface of the semiconductor light emitting element when the reflector is attached to the substrate.

  In addition, since the distance between the semiconductor light emitting element and the optical member can be always kept constant by the protrusions, luminance unevenness and color unevenness occur due to a change in the distance between the semiconductor light emitting element and the optical member. Can be prevented.

  Furthermore, since it is possible to dissipate the heat generated from the semiconductor light emitting element to the outside of the backlight device through the protrusion and the substrate, luminance unevenness due to fluctuations in the light emission characteristics of the semiconductor light emitting element as the temperature rises. It is possible to prevent the occurrence of color unevenness and the decrease in color balance.

  Hereinafter, a first embodiment of a backlight device of the present invention will be described in detail with reference to FIGS. 1 to 3 for a direct type backlight device using LEDs. The description is omitted. Here, FIG. 1 is an enlarged cross-sectional side view of an essential part showing a configuration example of the backlight device of the present embodiment. FIG. 2A is a side sectional view showing a configuration example of the backlight device of the present embodiment. b) The principal part top view, FIG. 3: is a principal part expanded sectional side view which shows the other structural example of the backlight apparatus of this embodiment.

  As shown in FIGS. 1 and 2, the direct-type backlight device using the LED of this embodiment includes a surface light source in which a plurality of LED elements 1 are arranged on a substrate 2 and a space between the LED elements 1. And a reflecting plate 3 installed on the substrate 2 and an optical member such as a diffusion plate 5 located on the light emitting side of the surface light source and the reflecting plate 3. Here, the board | substrate 2 is formed with materials, such as aluminum material with favorable heat conductivity, Comprising: The function of a heat sink is also combined. In addition, a conical protrusion 2 a that protrudes closer to the diffusion plate 5 than the LED element 1 is integrally formed on the substrate 2.

  Further, the reflector 3 is formed of a material such as an aluminum reflector, white polyester (foamed and mixed with scattering material), silver vapor-deposited polyester, etc., and the LED element 1 is fitted into the reflector 3. In addition to the through hole to be formed, a circular insertion hole 3a through which the projection 2a of the substrate 2 described above is inserted is provided.

  In this embodiment, a group of light emitting elements of three primary colors including a red light emitting LED, a green light emitting LED, and a blue light emitting LED is used as a set of modules, and a linear white light source in which these are arranged in series is arranged in the horizontal direction of the screen ( Although the surface light sources are arranged side by side in the short side direction), the present invention is not limited to this. For example, a linear white light source in which modules composed of LED element groups of three primary colors are arranged in series in the screen vertical direction (long side direction) The surface light source may be configured side by side, or the surface light source may be configured by arranging modules composed of LED element groups of three primary colors in a matrix, for example. Furthermore, you may implement | achieve a white surface light source using white light emitting LED.

  Moreover, in this embodiment, although the protrusion part 2a is integrally molded with the same material as the board | substrate 2, not only this but with the heat dissipation material with favorable heat conductivity, it forms as a separate member from the board | substrate 2, You may fix and provide in the predetermined position on the board | substrate 2. FIG. Also in this case, it is desirable that the protruding portion 2a be formed of a white high-reflecting material, like the reflecting plate 3.

  Here, as shown in FIG. 2 (b), a plurality of protrusions 2a are provided so as to be positioned in the middle of adjacent linear light sources, and the protrusions 2a adjacent in the vertical direction or the horizontal direction are horizontal. It is arranged in a so-called staggered pattern so as not to be in the same position in the direction or the vertical direction. This is to disperse the influence of the luminance by the protrusion 2a so as not to stand out. Needless to say, a plurality of insertion holes 3a of the reflecting plate 3 are provided at positions corresponding to the protrusions 2a.

  Furthermore, an optical member such as a diffusing plate 5 is provided on the light emitting side of the surface light source and the reflecting plate 3 configured as described above. As the diffusing plate 5, a transparent acrylic resin plate provided with irregularities for scattering light or a transparent acrylic resin containing particles that scatter light is used as a plate. A desired image display is performed by installing a liquid crystal display panel in front of the diffusion plate 5 (upper side in FIG. 2A) with a predetermined optical sheet such as a prism sheet (light collecting sheet) interposed therebetween. Is possible.

  In the backlight device configured as described above, when the reflecting plate 3 is installed on the substrate 2, both the projections 2 a on the substrate 2 are inserted into the corresponding insertion holes 3 a of the reflecting plate 3. Since the protrusion 2a on the substrate 2 exhibits a guide function regarding installation of the reflecting plate 3 on the substrate 2, the mounting position of the reflecting plate 3 with respect to the substrate 2 can be achieved. Accuracy can be improved. Accordingly, it is possible to prevent an error in the attachment position of the reflecting plate 3 with respect to the substrate 2 in an assembly process and the like, and damage the light emitting surface of the LED element 1 and the like by the reflecting plate 3. It is possible to suppress the occurrence of luminance unevenness and color unevenness.

  Further, in the backlight device of this embodiment, as shown in FIG. 2A, the tip of the protrusion 2 a is the reflection plate 3 in a state where the reflection plate 3 is installed at a predetermined position on the substrate 2. It abuts against the back surface of the diffusion plate 5 installed on the frame to prevent the diffusion plate 5 from being bent (warped) toward the reflection plate 3 due to heat or the like. That is, since the distance between the LED element 1 and the diffusion plate 5 can be maintained at a certain distance or more by the protrusion 2a integrally provided on the substrate 2, the distance between the LED element 1 and the diffusion plate 5 is predetermined. Luminance unevenness and color unevenness caused by the following can be suppressed.

  Furthermore, in the backlight device of this embodiment, since the substrate 2 and the protrusion 2a are formed of a heat dissipation material having good thermal conductivity, the heat generated from the LED element 1 is transmitted through the protrusion 2a and the substrate 2. The heat can be exhausted to the outside (rear side) of the space surrounded by the reflecting plate 3 and the diffusing plate 5. As a result, not only can the deflection (warpage) of the diffusion plate 5 be prevented, but also fluctuations in the light emission characteristics of the LED element 1 due to the environmental temperature can be suppressed, resulting in luminance unevenness, color unevenness, and color balance deterioration. Can be prevented.

  In the configuration example of the present embodiment described above, the reflector 3 is installed on the substrate 2 avoiding the metal-embedded PCB 4 on which the circuit or wiring for driving the LED element 1 is disposed. 3, as in another configuration example of the present embodiment shown in FIG. 3, a through hole is formed so that the light emitting portion of the LED element 1 is fitted, and the portion other than the LED light emitting portion (metal-embedded PCB 4) is covered. The present invention may be applied to an apparatus that improves the surface area coverage of the reflecting plate 13 by providing the reflecting plate 13.

  Also in this case, if the reflector 13 is provided with an insertion hole 13a through which the protrusion 2a of the substrate 2 is inserted, the protrusion 2a functions as a positioning guide when the reflector 13 is installed on the substrate 2. good. In addition, it is needless to say that after the assembly, the projecting portion 2a maintains the distance between the LED element 1 and the diffusion plate 5 and also functions to dissipate heat generated by the LED element 1 to the outside of the backlight device.

  As described above in detail, the backlight device according to the present embodiment includes the surface light source in which a plurality of LED elements (semiconductor light emitting elements) 1 are arranged on the substrate 2 and the space between the LED elements 1 so as to fill the space. A backlight device including a reflecting plate 3 installed on a substrate 2 and an optical member such as a diffuser plate 5 positioned on the light emitting side of the surface light source and the reflecting plate 3. In addition to providing a protruding portion 2a that protrudes toward the diffusion plate 5 from the LED element 1, an insertion hole 3a through which the protruding portion 2a is inserted is provided in the reflecting plate 3.

  This makes it possible to easily improve the mounting position accuracy of the reflecting plate 3 with respect to the substrate 2 with a very simple configuration, and therefore the light emitting surface of the LED element 1 when the reflecting plate 3 is mounted on the substrate 2. It is possible to prevent luminance unevenness and color unevenness due to damage. In addition, since the distance between the LED element 1 and the diffusion plate 5 can be always kept constant by the protrusion 2a, luminance unevenness and color due to the change in the distance between the LED element 1 and the diffusion plate 5 can be maintained. Unevenness can be prevented.

  Furthermore, since the heat generated from the LED element 1 can be radiated outside the backlight device through the protrusion 2a and the substrate 2, the light emission characteristics of the LED elements 1 fluctuate as the temperature rises. It is possible to prevent occurrence of luminance unevenness and color unevenness and deterioration of color balance.

  In the first embodiment of the present invention, the protrusion 2a is formed in a conical shape. However, in order to further improve the positioning accuracy between the reflector 3 and the substrate 2, the protrusion 2a is formed in a polygonal pyramid. While forming in a shape, it is good also considering the penetration holes 3a and 13a as a polygonal shape corresponding to this.

  In the above-described first embodiment of the present invention, the backlight device using only the LED (semiconductor light emitting element) as the light source has been described. However, the present invention includes an LED (semiconductor light emitting element) and other light sources. You may apply to the used backlight apparatus.

  In this regard, a backlight device using two types of light sources, for example, an LED (semiconductor light emitting element) and a cold cathode fluorescent lamp (CCFL) will be described below with reference to FIG. 4 as a second embodiment of the present invention. The same parts as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted. Here, FIG. 4 is a plan view of an essential part showing a configuration example of the backlight device of the present embodiment.

  As shown in FIG. 4, the direct type backlight device of the present embodiment has a plurality of CCFLs 6 in the screen short side direction (vertical direction) so that the longitudinal direction thereof is parallel to the screen long side direction (horizontal direction). A linear light source in which a plurality of LED elements 1 are arranged in series is arranged between adjacent CCFLs 6 so as to be parallel to the CCFL 6 to constitute a surface light source.

  Here, in order to improve color reproducibility and increase the color purity of red, a phosphor of two colors including at least green and blue among red, green and blue constituting the three primary colors of light is used. The surface light source is formed from the CCFL having the light emitting element group and the light emitting element group having at least the red light emitting LED, but of course, the present invention is not limited to this, for example, a white light emitting CCFL having phosphors of three primary colors of light, a red light emitting LED, A surface light source may be formed from a light emitting element group of three primary colors including a green light emitting LED and a blue light emitting LED.

  Also in the present embodiment, the protrusion 2a is provided on the substrate 2 on which the LED element 1 is installed, and the reflector 3 installed on the substrate 2 so as to fill the space between the LED elements 1 is provided. An insertion hole 3a through which the protruding portion 2a is inserted is provided, and this makes it possible to easily improve the mounting position accuracy of the reflecting plate 3 with respect to the substrate 2.

  Here, the protrusion 2a is provided between the LED elements 1 on each linear light source formed by arranging the LED elements 1 in series. For example, when a linear white light source in which three primary color light emitting element groups including a red light emitting LED, a green light emitting LED, and a blue light emitting LED are used as a set of modules and these are arranged in series is used, the protrusion 2a is a predetermined module. It is provided so as to be located between them.

  Also here, the protrusions 2a adjacent in the vertical direction or the horizontal direction are arranged in a so-called staggered pattern so as not to be in the same position in the horizontal direction or the vertical direction. By dispersing the influence of the luminance, it is possible to suppress as much as possible that the luminance unevenness and the color unevenness due to the protrusion 2a are conspicuous.

  In the present embodiment, the distance between the LED element 1 and the diffusion plate 5 can always be kept constant by the protrusion 2a provided integrally with the substrate 2, and the heat conduction can be maintained. Needless to say, the heat generated from the LED element 1 and the CCFL 6 can be radiated to the outside of the backlight device through the protrusion 2a and the substrate 2 formed of a good heat dissipation material.

  The CCFL 6 is attached at a predetermined position via various lamp holders after the reflector 3 is installed on the substrate 2. Further, also in the present embodiment, a liquid crystal display panel is installed on the frame of the reflector plate 3 with a predetermined optical sheet such as the diffuser plate 5 or a prism sheet (light collecting sheet) interposed therebetween, and desired image display is performed. It becomes possible.

It is a principal part expanded side sectional view which shows the example of 1 structure of the backlight apparatus in the 1st Embodiment of this invention. It is (a) sectional side view which shows the example of 1 structure of the backlight apparatus in the 1st Embodiment of this invention, (b) It is a principal part top view. It is a principal part expanded side sectional view which shows the other structural example of the backlight apparatus in the 1st Embodiment of this invention. It is a principal part top view which shows one structural example of the backlight apparatus in the 2nd Embodiment of this invention. It is (a) principal part top view which shows one structural example of the conventional backlight apparatus, (b) principal part expansion side sectional drawing. It is (a) principal part top view which shows the other structural example of the conventional backlight apparatus, (b) principal part expansion side sectional drawing. It is (a) sectional side view which shows the other structural example of the conventional backlight apparatus, (b) It is a principal part top view.

Explanation of symbols

1 LED element 2 Substrate (also used as heat sink)
2a Protruding part 3 Reflecting plate 3a Insertion hole 4 Metal embedded PCB
5 Diffuser 6 CCFL
13 Reflector 13a Insertion hole

Claims (7)

A surface light source formed by arranging a plurality of semiconductor light emitting elements on a substrate;
A reflector installed on the substrate so as to fill a space between the semiconductor light emitting elements;
A backlight device comprising the surface light source and an optical member positioned on the light emitting side of the reflector,
On the substrate, a protrusion that protrudes toward the optical member than the semiconductor light emitting element is provided, and
A backlight device, wherein the reflector is provided with an insertion hole through which the protrusion is inserted.   The backlight device according to claim 1, wherein the protrusion is formed integrally with the substrate.   The backlight device according to claim 1, wherein the protrusion is formed of a heat dissipation material having good thermal conductivity.   4. The backlight device according to claim 1, wherein the protrusion is formed of a white highly reflective material. 5. The surface light source is a linear light source in which the semiconductor light emitting elements are arranged in series and arranged in a predetermined order.
The backlight device according to claim 1, wherein the protrusion is provided at an intermediate position between adjacent linear light sources. The surface light source is a linear light source in which the semiconductor light emitting elements are arranged in series and arranged in a predetermined order.
5. The backlight device according to claim 1, wherein the protrusion is provided between semiconductor light emitting elements in each linear light source. 7. A liquid crystal display device comprising the backlight device according to claim 1 and a liquid crystal display panel for displaying an image.

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