JP4051941B2 - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein heat generated by a fluorescent lamp can be efficiently dissipated to the outside of a backlight without damaging the intensity of the backlight. <P>SOLUTION: Heat generated principally in the vicinity of both ends of a fluorescent lamp 4 supported by a lamp holder 3 is radiated to the outside through a venthole 8 by providing the venthole 8 on the lamp holder 3 forming the side surface of the backlight 1. Thereby, luminance unevenness and the like caused by high temperature of the inside of the backlight 1 can be suppressed. Further, reduction of the intensity of the backlight 1 can be suppressed by providing the venthole at the lamp holder 3. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly to a backlight used in a liquid crystal display device.
[0002]
[Prior art]
In a liquid crystal display device, a backlight is usually provided behind the liquid crystal panel. As this backlight, a direct type and an edge light type are generally well known. However, in the case of a large-sized liquid crystal display device exceeding 15 inches, the luminance may be insufficient when the edge light type is used. Accordingly, direct type backlights are often used for large liquid crystal display devices.
[0003]
In the case of this direct type backlight, the entire backlight is very hot due to the heat generated from the fluorescent tube used as the light source. Therefore, the luminous efficiency of the fluorescent tube is lowered, and the light intensity of the fluorescent tube gradually decreases during use. In addition, heat is transmitted to the liquid crystal panel, and this influence causes display unevenness. Further, if the heat dissipation measures are insufficient, there is a possibility that problems such as exceeding the specified temperature that guarantees the operation of the components used in the liquid crystal display device may occur.
[0004]
Therefore, JP-A-6-273765 and JP-A-2001-297623 have been conventionally known.
[0005]
[Problems to be solved by the invention]
However, as described in JP-A-6-273765 and JP-A-2001-297623, if a ventilation hole is provided on the back surface or side surface of the backlight formed by the backlight chassis, There is a risk that the strength of the light will decrease, causing deflection, twisting, etc. due to vibration. In addition, it is difficult to make a complicated shape of a metal such as aluminum compared to a resin, which is costly.
[0006]
In addition, as a result of research on heat generated from fluorescent tubes, heat generated from fluorescent tubes is generated around the electrodes at both ends, and this heat is transmitted to the glass part of the fluorescent tube and the air around the fluorescent tube. all right. Therefore, providing a vent hole only on the upper surface of the backlight does not provide sufficient heat dissipation measures.
[0007]
The present invention has been made in view of the above problems, and provides a liquid crystal display device capable of efficiently releasing heat generated from a fluorescent tube to the outside of the backlight without impairing the strength of the backlight. Objective.
[0008]
[Means for Solving the Problems]
The present invention is a liquid crystal display device comprising a liquid crystal panel and a direct backlight located at the rear of the liquid crystal panel, a backlight chassis forming a side surface and a back surface of the backlight, and at least one of the backlights. A lamp holder that forms one side surface, a fluorescent tube that is positioned in front of the backlight chassis and supported by the lamp holder, and a diffusion plate that is positioned in front of the fluorescent tube. A vent hole is provided, and when the vent hole is viewed from the liquid crystal panel side, at least a part of the vent hole is located behind the fluorescent tube.
[0009]
According to the present invention, heat generated in the vicinity of both ends of the fluorescent tube can be efficiently released to the outside through the vent hole provided in the lamp holder. In addition, it is possible to suppress the influence on the liquid crystal panel due to a decrease in the reflected light at the vent hole.
[0010]
The present invention is also the liquid crystal display device characterized in that two opposite side surfaces of the backlight are formed by a plurality of the lamp holders, and vent holes are respectively provided on the two side surfaces.
[0011]
The present invention is the liquid crystal display device, wherein the lamp holder is made of resin.
[0012]
According to the present invention, it is possible to relatively easily make a lamp holder that suppresses a decrease in strength due to the provision of the vent hole, and thus it is possible to suppress a decrease in the strength of the entire backlight.
[0013]
The present invention is the liquid crystal display device, wherein the backlight is elongated in the left-right direction, and the lamp holder forms a short side surface of the backlight.
[0014]
According to the present invention, the number of fluorescent tubes can be reduced, and the number of vent holes can be reduced, so that a reduction in the strength of the entire backlight can be suppressed.
[0015]
The present invention is the liquid crystal display device characterized in that the lamp holder has a substantially U-shaped or L-shaped cross section.
[0016]
According to the present invention, it is possible to easily perform the connecting operation of the lead wire of the fluorescent tube through the opening portion of the lamp holder.
[0017]
The present invention is the liquid crystal display device, wherein a filter is attached to the vent hole.
[0018]
According to the present invention, dust or the like can be prevented from entering the backlight through the vent hole.
[0022]
Further, the present invention is the liquid crystal display device characterized in that the side surface is inclined so as to approach the opposite side surface from the liquid crystal panel side toward the back side.
[0023]
According to the present invention, the light from the fluorescent tube hitting the lamp holder can be efficiently reflected toward the liquid crystal panel.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a backlight 1 used in a liquid crystal display device according to the present invention. 2 is a cross-sectional view taken along the line AA in FIG. The backlight 1 includes a backlight chassis 2, a lamp holder 3, a fluorescent tube 4, and a diffusion plate 5 (not shown in FIG. 1). The backlight chassis 2 is made of a sheet metal such as aluminum, and has a thickness that does not easily cause bending, twisting, or the like due to vibration or the like. The backlight chassis 2 is formed with the upper surface and the lower surface of the backlight 1 by bending the upper and lower ends of the aluminum sheet metal together with the back surface of the backlight 1.
[0025]
On both left and right ends of the aluminum sheet metal, lamp holders 3 formed in a predetermined shape with a resin such as polycarbonate are installed so as to close the left and right side portions of the backlight chassis 2 that are opened. The lamp holder 3 has a substantially U-shaped cross section, and is attached to the backlight chassis 2 with screws or the like via the bottom surface portion of the lamp holder 3. The lamp holder 3 is white so as to easily reflect light from the light source. The left and right side surfaces of the backlight 1 are formed by the side surfaces of the lamp holder 3.
[0026]
A lamp chamber 11 of the backlight 1 is constituted by the back and top and bottom sides of the backlight 1 made up of the backlight chassis 2 and the left and right sides of the backlight 1 made up of the lamp holder 3. The lamp chamber 11 is long in the left-right direction. A plurality of fluorescent tubes 4 exist in the lamp chamber 11. The fluorescent tube 4 is coated with a phosphor. Electrodes 14 are provided at both ends inside the fluorescent tube 4, and lead wires 24 connected to the electrodes extend to the outside of the fluorescent tube 4. A gas such as mercury is sealed inside the fluorescent tube 4, and ultraviolet rays emitted from the gas excited by the discharge emit light upon the phosphor.
[0027]
In this embodiment, the interval between the fluorescent tubes 4 adjacent to each other is set to about 25 to 30 mm. In order to irradiate the liquid crystal panel 6 with light as uniformly as possible, the interval between the fluorescent tubes 4 should be set to this level. In order to support and fix the fluorescent tubes 4, holes are formed in the side portions of the lamp holder 3 by the number of fluorescent tubes 4. Since the fluorescent tube 4 is not damaged by vibration or the like, the hole is in close contact with the fluorescent tube 4 with the same size as the diameter of the fluorescent tube 4, or is slightly larger than the diameter of the fluorescent tube 4 and is fluorescent through a buffer. It is in close contact with the tube 4. It is located 2-3 mm forward from the back of the backlight 1. The fluorescent tube 4 is supported and fixed by the lamp holder 3 through a part of the fluorescent tube 4 in the hole.
[0028]
On the back of the side surface portion of the lamp holder 3, wirings (not shown) including lead wires 24 extending from the fluorescent tube 4 and near both ends of the fluorescent tube 4 are located. There is no side surface portion on the opposite side of the side surface portion of the lamp holder 3 having a substantially U-shaped cross section, and there is an opening portion. Accordingly, an opening portion facing the outside of the backlight 1 is formed in the lamp holder 3 at a position opposite to the lamp chamber 11 side. Because of the opening portion, for example, the connection work of the lead wires 24 can be easily performed. Therefore, particularly in the case of a large-sized liquid crystal display device using a plurality of fluorescent tubes 4, the efficiency of the connection work of the lead wires 24 is very high. Go up. The same effect can be obtained even if the cross section of the lamp holder 3 is not only substantially U-shaped but also substantially L-shaped.
[0029]
A diffusion plate 5 is disposed in front of the fluorescent tube 4 so as to cover the lamp chamber 11. The light emitted from the fluorescent tube 4 is made substantially uniform light on the entire irradiation surface by the diffusion plate 5, and this light is irradiated to the liquid crystal panel 6 indicated by a broken line on the front surface of the diffusion plate 5. By providing the backlight 1 and the liquid crystal panel 6, the liquid crystal display device of the present invention is obtained. In order to efficiently reflect the light emitted from the fluorescent tube 4 to the backlight chassis 2 toward the liquid crystal panel 6 side, in many cases, a reflector is attached to the lamp chamber 11 side of the backlight chassis 2. Not shown.
[0030]
In this embodiment, vent holes 8 are provided in the lamp holders 3 at both ends (only one end is shown). The ventilation holes 8 are respectively located between the adjacent fluorescent tubes 4. The shape of the hole is rectangular. The lamp chamber 11 and the outside of the backlight 1 are connected via the vent hole 8. As a result of studying heat generated from the fluorescent tube 4, heat is generated around the electrodes 14 located at both ends of the fluorescent tube 4, and this heat is transmitted to the glass portion of the fluorescent tube 4 and the air around the fluorescent tube 4. I knew it would go. Therefore, by providing the vent hole 8 in the lamp holder 3 that is supported and fixed near both ends of the fluorescent tube 4, the heat generated near both ends of the fluorescent tube 4 can be efficiently released before accumulating inside the backlight 1. . Further, by preventing the temperature of the entire backlight 1 from becoming too high, it is possible to suppress the occurrence of display unevenness occurring in the display panel 6 and to prevent the luminous efficiency of the fluorescent tube 4 from being lowered.
[0031]
Further, when the lamp holder 3 is resin-molded, the vent hole 8 is formed integrally with the lamp holder 3. Since the lamp holder 3 is made of resin, the lamp holder 3 can be shaped so as to prevent the strength of the lamp holder 3 from being lowered due to the provision of the vent holes 8. In the present embodiment, the vent hole 8 has a cylindrical shape in which the outer periphery of the vent hole 8 is covered with resin even inside the lamp holder 3. At this time, the lamp holder 3 may be manufactured by thickening the resin only in this portion. In addition, in order to suppress a decrease in strength of the lamp holder 3, the corner portion inside the lamp holder 3 having a U-shaped cross section may be thickened. Therefore, there is little decrease in the strength of the entire backlight 1 due to the provision of the vent holes 8. In addition, it is difficult to make such a shape using a metal, and the cost becomes high, so that the overall cost is lower than the case where the vent hole 8 is provided in a metal one.
[0032]
Further, in this embodiment, since the ventilation hole 8 is not provided in the backlight chassis 2, the strength of the entire backlight 1 is relatively low, and there is little risk of bending or twisting due to vibration or the like. In particular, in the case of a large-sized liquid crystal display device using a direct type backlight, not only the backlight 1 but also the liquid crystal panel 6 is naturally large, so that the device itself becomes considerably heavy. Therefore, if the vent hole 8 is provided in the backlight chassis 2, there is a high risk of bending, twisting, etc. due to the influence of the weight of the entire device, etc. The present invention becomes more effective as the liquid crystal display device becomes larger. become. Even if a reflector is attached to the backlight chassis 2, it is not necessary to align the ventilation holes of the backlight chassis and the ventilation holes of the reflector, and work efficiency is good because the attaching operation is easy.
[0033]
In the present embodiment, the left-right direction of the backlight 1 is long. The plurality of fluorescent tubes 4 are arranged in the left-right direction. Vent holes 8 are provided on the left and right side surfaces that are shorter than the upper and lower side surfaces. The reduction in strength of the backlight 1 as a whole is less when the vent hole 8 is provided on the short side than when the vent hole 8 is provided on the long side. Further, when the interval between the fluorescent tube 4 and the fluorescent tube 4 is set to about 25 to 30 mm, the fluorescent tube 4 arranged in the longitudinal direction is longer than the fluorescent tube 4 arranged in the vertical direction. The number of tubes 4 is small. Thereby, the number of the vent holes 8 can be reduced, and the strength reduction of the entire backlight 1 can be suppressed as compared with the case where the vent holes 8 are provided on the long side surfaces. Furthermore, the light emission efficiency of the entire backlight 1 is higher and the luminance is higher when the long fluorescent tube 4 is used than when the short fluorescent tube 4 is used.
[0034]
In this embodiment, the vent hole 8 is formed on the back side of the fluorescent tube 4, and the back side of the opening of the vent hole 8 is in contact with the back side. Since the reflection of light emitted from the fluorescent tube 4 is reduced at the vent hole 8 portion, if the vent hole 8 is provided in front of the fluorescent tube 4, the luminance unevenness of the liquid crystal panel 6 is easily noticeable due to the influence of the vent hole 8. . However, by providing the vent hole 8 on the back side of the fluorescent tube 4, there is little influence due to the decrease in the reflected light at the vent hole 8, and the light emitted from the fluorescent tube 4 can be used effectively, The occurrence of uneven brightness can be suppressed, and the liquid crystal display device has a uniform brightness.
[0035]
In the case where the vent hole 8 is provided on the back side of the fluorescent tube 4, even if a part of the vent hole 8 is located directly behind the fluorescent tube 4 when the vent hole 8 is viewed from the liquid crystal panel 6 side. Good. Further, when the vent hole 8 is viewed from the liquid crystal panel 6 side, the vent hole 8 may be located completely behind the fluorescent tube 4. Since even a part of the vent hole 8 is located behind the fluorescent tube 4, the influence of the decrease in the reflected light at the vent hole 8 is further reduced, so that the occurrence of luminance unevenness can be further suppressed.
[0036]
Further, in this embodiment, a filter 9 is attached to the vent hole 8. When dust or the like enters the lamp chamber 11, a shadow appears on the liquid crystal panel 6 due to the dust. This filter 9 is for preventing dust and the like from entering the lamp chamber 11 through the vent hole 8. However, if the size of the hole in the filter 9 is made too small, the air flow will deteriorate. In addition, if the garbage is very small, the influence on the display is small. Therefore, the size of the hole of the filter 9 is optimally about 0.1 to 0.2 mm.
[0037]
Next, another embodiment of the present invention will be described. 3 is an enlarged view of the main part of the backlight used in the liquid crystal display device of the present invention, and is a cross-sectional view of the main part at the same position as the AA cross section of FIG. In addition, about the part which overlaps with the said Example, while using the same code | symbol, description is abbreviate | omitted. In the present embodiment, the left and right side surfaces of the backlight 1 are inclined. Specifically, the side surface of the backlight 1 formed by the lamp holder 3 ′ is inclined so as to approach the side surface of the opposing backlight 1 as it goes from the front side where the liquid crystal panel 6 is located toward the back side of the backlight 1. is doing. As a result, the light coming toward the lamp holder 3 ′ can be efficiently reflected toward the liquid crystal panel 6, resulting in a liquid crystal display device with high brightness and uniform brightness.
[0038]
In the present invention, heat generated around the vicinity of the electrodes 14 at both ends of the fluorescent tube 4 is released to the outside through the vent hole 8 provided in the lamp holder. Various forms can be adopted as the size, shape, and the like of the vent hole 8. For example, one vent hole 8 may be provided on the back side of the fluorescent tube 4 and straddling all the fluorescent tubes 4. Further, the size of the vent holes 8 may not be the same, but the size may be changed depending on the installation position of each vent hole 8. For example, since normal heat flows upward, the vent hole 8 provided in the lamp holder may be enlarged as it goes from the lower side surface of the backlight 1 to the upper side surface.
[0039]
【The invention's effect】
As described above, according to the liquid crystal display device of the present invention, the heat generated around the both ends of the fluorescent tube is released to the outside through the vent holes near both ends of the fluorescent tube. Heat can be released outside the backlight.
[0040]
In addition, since the vent hole is provided in the lamp holder, it is possible to suppress a decrease in the strength of the entire backlight as compared with the case where the vent hole is provided on the back surface or side surface of the backlight chassis.
[0041]
Furthermore, since a filter is attached to the vent hole, dust can be prevented from entering the backlight through the filter.
[Brief description of the drawings]
FIG. 1 is a perspective view of a backlight used in a liquid crystal display device of the present invention.
FIG. 2 is an enlarged view of a main part of a backlight used in the present invention, and is a cross-sectional view taken along the line AA in FIG.
FIG. 3 is a cross-sectional view showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Backlight 2 Backlight chassis 3, 3 'Lamp holder 4 Fluorescent tube 6 Liquid crystal panel 8 Vent hole 9 Filter 14 Electrode

Claims (7)

  A liquid crystal display device comprising a liquid crystal panel and a direct-type backlight positioned at the rear of the liquid crystal panel, forming a backlight chassis forming the side surface and the back surface of the backlight, and forming at least one side surface of the backlight A lamp holder, a fluorescent tube positioned in front of the backlight chassis and supported by the lamp holder, and a diffusion plate positioned in front of the fluorescent tube, and the lamp holder is provided with a vent hole When the air hole is viewed from the liquid crystal panel side, at least a part of the air hole is located behind the fluorescent tube.   The liquid crystal display device according to claim 1, wherein two opposite side surfaces of the backlight are formed by the plurality of lamp holders, and a vent hole is provided in each of the two side surfaces.   The liquid crystal display device according to claim 1, wherein the lamp holder is made of resin.   4. The liquid crystal display device according to claim 1, wherein the backlight is long in a left-right direction, and the lamp holder forms a short side surface of the backlight.   The liquid crystal display device according to any one of claims 1 to 4, wherein the lamp holder has a substantially U-shaped or L-shaped cross section.   The liquid crystal display device according to claim 1, wherein a filter is attached to the vent hole.   The liquid crystal display device according to claim 1, wherein the side surfaces are inclined so as to approach the opposite side surfaces from the liquid crystal panel side toward the back side.

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