JP2007086648A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of quite simply preventing the generation of buckling of an optical sheet and wrinkles due to thermal expansion of the optical sheet. <P>SOLUTION: A fixture 25 being as a frame which comprises a first opening part 26a having an area smaller than the area of the optical sheet 30 and a second opening part 26b having a depth larger than the depth of the optical sheet 30 and an area larger than the area of the optical sheet 30 is fixed on a circumferential part of a backlight chassis 21 while the optical sheet 30 is located on the second opening part 26b. Edge parts of the front surface side of double side walls arranged opposite to each other in the backlight chassis 21 form a curved shape and the optical sheet can be simply curved by arranging the planar optical sheet along the backlight chassis 21. Because of the curvature of the optical sheet 30, the strength for bending of the optical sheet increases and the generation of buckling of the optical sheet by own-weight can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a large screen size.

  Liquid crystal display devices are characterized by their small size, thinness, and low power consumption. In recent years, liquid crystal display devices have become widespread as displays replacing conventional CRTs due to their improved display quality. Unlike a self-luminous device, a liquid crystal display device requires a backlight as a light source, and displays an image by controlling light transmittance determined by the electro-optical characteristics of the liquid crystal substance.

  In the liquid crystal display device, the display quality is improved by providing an optical sheet in the gap between the liquid crystal panel and the backlight. As a method for holding the optical sheet, Patent Document 1 discloses a fastener that can position and fix the planar light emitting element or the light guide and the optical sheet without using the double-sided tape. An illuminating device and a liquid crystal display device using the above are disclosed.

  Further, in Patent Document 2, an optical sheet is held by a sticking head in a state where a laminated body in which an optical sheet, an adhesive layer, and a release sheet are laminated in this order is elastically supported at a release sheet peeling position. An optical sheet affixing method and an apparatus for affixing an optical sheet accurately at a predetermined position by absorbing thickness variation of the sheet by elastic support are disclosed.

By the way, there is a problem that the optical sheet is bent in a wave shape by heat from the backlight, and uneven brightness occurs. Therefore, in Patent Document 3, an optical sheet is positioned between the light body and the liquid crystal cell, and by holding a part of one side of the light body on the side of the linear light source body between the light body and the liquid crystal cell, There has been disclosed a liquid crystal display device that can absorb the deflection on the other side of the optical sheet and reduce the deflection of the optical sheet even if one side of the optical sheet is bent by heat.
Japanese Patent Laid-Open No. 2004-233383 JP 2004-86075 A JP 2004-53682 A

  However, the optical sheet is generally thin, and as the screen size increases, there is a problem that the optical sheet buckles due to its own weight. It is possible to prevent buckling of the optical sheet by attaching the optical sheet with high strength. However, as the attachment is performed with high strength, the optical sheet at the attachment position is thermally expanded, and the optical sheet is attached. Wrinkles occur. Thus, there has been a demand for a technique for preventing buckling and wrinkling of the optical sheet.

  The present invention has been made in view of such circumstances, and even if the screen size is increased by adopting a configuration in which the optical sheet is arranged in a backlight in a curved state, the optical sheet is It is an object of the present invention to provide a liquid crystal display device that can prevent buckling extremely easily.

  Further, according to the present invention, as the base of the backlight, the edges on the opening side of the two opposite side walls of the rectangular parallelepiped box with the liquid crystal panel opened are curved, and the edge of the optical sheet is along the curved shape. An object of the present invention is to provide a liquid crystal display device that can easily obtain a desired curved shape by adopting a configuration in which the above-mentioned is disposed.

  Furthermore, the present invention provides a frame having a first opening having an area smaller than the area of the optical sheet and a second opening having an area deeper than the thickness of the optical sheet and larger than the area of the optical sheet. Even if the optical sheet is thermally expanded, there is no force acting on the optical sheet other than gravity by adopting a configuration in which the optical sheet is fixed to the periphery of the box while being arranged in the opening. An object of the present invention is to provide a liquid crystal display device capable of preventing wrinkles due to the above.

  Furthermore, the present invention provides the first convex portion and the first convex portion by providing the first convex portion on the front surface or the back surface of the optical sheet and the second convex portion corresponding to the first convex portion on the box or the frame. An object of the present invention is to provide a liquid crystal display device in which the movement range of the optical sheet is regulated by the two convex portions and the optical sheet can be prevented from falling off the backlight.

  Furthermore, according to the present invention, the central portion of the optical sheet is curved in the direction of the light source, so that when the liquid crystal display screen is viewed from the center, the light is concentrated on the central portion to improve display quality. An object of the present invention is to provide a liquid crystal display device capable of achieving the above.

  A liquid crystal display device according to the present invention includes a liquid crystal panel, a backlight having one or more light sources on the back side of the liquid crystal panel, and an optical sheet provided in a gap between the liquid crystal panel and the backlight. In the display device, the optical sheet is arranged in the backlight in a curved state.

  In the present invention, since the optical sheet is arranged on the backlight in a curved state, it is possible to prevent the occurrence of buckling of the optical sheet due to its own weight even when the screen size is large. Therefore, the occurrence of uneven brightness can be prevented, and the deterioration of display quality can be suppressed.

  In the liquid crystal display device according to the present invention, the light source is provided in a rectangular parallelepiped box having an opening on the liquid crystal panel side, and the edge portions on the opening side of two opposing side walls of the box have a curved shape. The optical sheet is curved by disposing the end portion of the optical sheet along the curved surface shape.

  In the present invention, one or a plurality of light sources are provided in a rectangular parallelepiped box having an opening on the liquid crystal panel side, and the optical sheet is disposed by arranging the end of the optical sheet along the curved shape of the box. Bend. Since the edge portions on the opening side of the two opposing side walls of the box body have a curved surface shape, the optical sheet can be easily bent by arranging a planar optical sheet along the box body. Further, by determining the shape of the edge portion of the box according to the curved shape required for the optical sheet, the optical sheet can be formed into a desired curved shape.

  The liquid crystal display device according to the present invention includes a frame having a first opening having an area smaller than the area of the optical sheet and a second opening having an area deeper than the optical sheet and larger than the area of the optical sheet. The frame is characterized in that the optical sheet is fixed to the peripheral edge of the box in a state where the optical sheet is disposed in the second opening.

  In the present invention, the optical sheet includes a frame having a first opening having an area smaller than the area of the optical sheet and a second opening having an area deeper than the thickness of the optical sheet and larger than the area of the optical sheet. It fixes to the peripheral part of a box, in the state arranged at the 2nd opening. Thereby, the optical sheet can move freely in the second opening. Even when the optical sheet is thermally expanded, there is no force acting on the optical sheet other than gravity, so that generation of wrinkles due to thermal expansion can be prevented very easily. Moreover, since the 1st opening part is smaller than the area of an optical sheet, it can prevent that an optical sheet falls.

  In the liquid crystal display device according to the present invention, the optical sheet has a first protrusion on the front surface or the back surface, and the box or the frame has a second protrusion corresponding to the first protrusion. The moving range of the optical sheet is regulated by the first convex portion and the second convex portion.

  In the present invention, the first convex portion is provided on the front surface or the back surface of the optical sheet, the second convex portion corresponding to the first convex portion is provided on the box or the frame, and the first convex portion and the second convex portion The movement range of the optical sheet is regulated. Thereby, it is possible to prevent the optical sheet from falling off the backlight. Even when the optical sheet is thermally expanded, the movement range of the optical sheet is restricted, and the light from the backlight is always emitted through the uniform optical sheet. Luminance does not vary depending on the position, and occurrence of luminance unevenness can be prevented.

  The liquid crystal display device according to the present invention is characterized in that the optical sheet has a central portion curved in the direction of the light source.

  In the present invention, since the central portion of the optical sheet is curved in the direction of the light source, the viewer of the liquid crystal display device usually views the screen from the center, so that the light is condensed and displayed at the central portion. The quality can be improved.

  According to the present invention, since the optical sheet is arranged in the backlight in a curved state, it is possible to prevent buckling of the optical sheet very easily even when the screen size is increased. it can.

  According to the present invention, as the base of the backlight, the edges on the opening side of the two opposite side walls of the rectangular parallelepiped box having the liquid crystal panel side opened are curved, and the edge of the optical sheet is along the curved shape. Since the portion is arranged, a desired curved shape can be easily obtained.

  According to the present invention, the optical sheet includes a frame having a first opening having an area smaller than the area of the optical sheet and a second opening having an area deeper than the thickness of the optical sheet and larger than the area of the optical sheet. 2 Since it is configured to be fixed to the peripheral portion of the box while being arranged in the opening, even if the optical sheet is thermally expanded, there is no force acting on the optical sheet other than gravity. Generation of wrinkles due to expansion can be prevented very easily.

  According to the present invention, since the first convex portion is provided on the front surface or the back surface of the optical sheet and the second convex portion corresponding to the first convex portion is provided on the box or the frame, the first convex portion and the second convex portion are provided. The movement range of the optical sheet can be regulated by the convex portion, and the optical sheet can be prevented from falling off the backlight.

  According to the present invention, since the central portion of the optical sheet is curved in the direction of the light source, when the liquid crystal display screen is viewed from the center, the light is concentrated on the central portion to improve the display quality. It has excellent effects such as being able to.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

  FIG. 1 is a perspective view showing an appearance of a liquid crystal display device according to the present invention, FIG. 2 is a perspective view showing a configuration of the liquid crystal display device according to the present invention, and FIG. 2 shows an internal configuration of the liquid crystal display device according to the present invention. It is described so that it can be understood.

  The liquid crystal display device according to the present invention includes a liquid crystal panel 10 and a backlight 20 provided on the back side of the liquid crystal panel 10, and the liquid crystal panel 10 and the backlight 20 are formed by a front cabinet 51 and a back cabinet 52. It is arranged in the space. The front cabinet 51 is provided with an opening 51a, and an image of the liquid crystal panel 10 is displayed through the opening 51a. The liquid crystal panel 10 and the backlight 20 are fixed to a support frame (not shown) having dimensions that match the outer dimensions of the liquid crystal panel 10. Two support columns extending in the vertical direction are fixed to the support frame so as to connect two sides facing the upper and lower sides of the support frame, and a stand 60 is attached to the support frame.

  A pair of transparent plates is disposed opposite to the liquid crystal panel 10, and a liquid crystal layer in which a liquid crystal material is sealed is formed in a gap between the two transparent plates. One transparent plate is formed with a transparent pixel electrode such as ITO or NESA arranged in a matrix and a TFT for controlling the supply of electric charge to the pixel electrode. A transparent common electrode called a common electrode is formed. The gate and source of the TFT are connected to the output stages of the gate driver and source driver, respectively.

  In the liquid crystal panel 10, on / off of each pixel is controlled by a gate signal input from the gate driver, and a data signal input from the source driver is applied to each pixel during the on period, whereby the electro-optical characteristics of the liquid crystal material. Controls the light transmittance determined by.

  In the backlight 20, a plurality of linear cold cathode ray discharge tubes (CCFL) 40 (see FIGS. 3 and 4) as light sources are juxtaposed in the vertical direction in a horizontally placed state, and white light close to natural light is provided on the front surface. The liquid crystal panel 10 is made incident. Further, the optical sheet 30 is arranged on the light emitting surface side of the backlight 20 in a state of being curved in the horizontal direction. In addition, you may use what arrange | positioned white LED and / or LED of multiple colors as a backlight.

3 is a cross-sectional view taken along line III-III in FIG. 2, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.
The backlight 20 has a rectangular parallelepiped box (backlight chassis) 21 whose front surface is opened as a base, and the front side edges of the two opposite side walls of the backlight chassis 21 have a curved shape. A reflective film 22 is formed on the inner wall of the backlight chassis 21. The reflective film 22 is provided in order to reflect the light emitted from the CCFL 40 toward the inner wall and increase the emission efficiency from the opening 20a.

  The fixture 25 is a frame in which a first opening 26 a having an area smaller than the area of the optical sheet 30 and a second opening 26 b having an area larger than the thickness q of the optical sheet 30 and larger than the area of the optical sheet 30 are connected. And the optical sheet 30 is being fixed to the peripheral part of the backlight chassis 21 in the state arrange | positioned in the 2nd opening part 26b. By fixing the fixture 25 to the backlight chassis 21, a groove (U-shaped space) 27 is formed.

  The width p of the groove 27 (that is, the depth of the second opening 26b) is designed to be larger than the thickness q of the optical sheet 30 (p> q). Therefore, the optical sheet 30 does not receive an interaction (force) from the backlight chassis 21 and the fixture 25 and can move freely in the groove 27. Moreover, since the 1st opening part 26a is smaller than the area of the optical sheet 30, the optical sheet 30 does not drop out.

  The optical sheet 30 has a rectangular shape with an aspect ratio of 4: 3 (or 16: 9), and is linear with respect to the vertical direction (FIG. 3). Curved in the direction of CCFL 40 (FIG. 4). Thus, since the optical sheet 30 is curved, the strength against bending of the optical sheet is increased, and even if the screen size is large (50 inches or more), the buckling of the optical sheet 30 due to its own weight occurs. Can be prevented.

  FIG. 5 is a diagram showing a state of the optical sheet in the backlight according to the present invention when the optical sheet is thermally expanded. FIG. 5A shows a state before the backlight is used, that is, before the CCFL 40 is turned on, and FIG. Each of the states when the backlight is in use, that is, when the CCFL 40 is lit, is shown.

  Since the optical sheet 30 is provided at a position where the distance from the CCFL 40 is about several centimeters, the optical sheet 30 is thermally expanded under the influence of heat generated when the CCFL 40 is turned on. Here, since the optical sheet 30 can move freely in the groove 27, the optical sheet 30 is not bent in a wave shape by heat from the backlight 20, and luminance unevenness does not occur.

  Moreover, as shown in FIG. 6, the convex part 30a is provided in the fixture 25 side of the optical sheet 30, and the convex part 25a is provided in the optical sheet 30 side of the fixture 25, and the optical sheet 30 is formed by the convex part 30a and the convex part 25a. The movement range R may be restricted (FIG. 6A). Or the convex part 30b is provided in the backlight chassis 21 side of the optical sheet 30, the convex part 21a is provided in the optical sheet 30 side of the backlight chassis 21, and the movement range R of the optical sheet 30 is regulated by the convex part 30b and the convex part 21a. You may make it do (FIG.6 (b)).

  If the movement range of the optical sheet 30 is restricted, it is possible to prevent the optical sheet 30 from falling off the backlight 20. Moreover, although the optical characteristic of the peripheral part of the optical sheet 30 may be inferior to the optical characteristic inside a peripheral part, since the peripheral part of the optical sheet 30 will be arrange | positioned outside an output area | region, the optical sheet 30 Even when the liquid crystal panel is thermally expanded, the light from the CCFL 40 is always emitted through the uniform optical sheet 30, so that the brightness does not vary depending on the position of the liquid crystal panel 10, and uneven brightness occurs. Can be prevented.

Next, a more detailed specific example will be described. FIG. 7 is a cross-sectional view of an essential part of the liquid crystal display device according to the present invention.
In the liquid crystal display device, a front cabinet 51 and a back cabinet 52 are fixed by screws 53, and various components are arranged in a space generated by fixing the front cabinet 51 and the back cabinet 52.

  A support plate 54 is fixed to the back cabinet 52, and the backlight chassis 21 is fixed to the support plate 54 with screws 55. That is, the backlight 20 is fixed to the back cabinet 52 via the support plate 54.

  The backlight chassis 21 is a box, and a reflection film 22 is formed on the inner wall thereof. The reflective film 22 is formed by evaporating a material having excellent light reflectivity such as aluminum. The CCFL 40 is fixed to the backlight chassis 21 by a known clip 41 provided at an appropriate position.

  Moreover, the two edge parts which the backlight chassis 21 opposes have a curved surface shape, and the edge part of the optical sheet 30 is arrange | positioned along this curved surface shape. The optical sheet 30 is formed by laminating a diffusion plate 31, a diffusion sheet 32, an R-BAF 33, and a D-BAF 34.

  Further, the fixing tool 25 is fixed to the side surface portion of the backlight chassis 21 with the screws 56, whereby the grooves 27 are formed. The end of the optical sheet 30 is disposed in the groove 27 so that the optical sheet 30 can move freely.

  The liquid crystal panel 10 is disposed on the front side of the optical sheet 30. Specifically, the peripheral portions of the front and back surfaces of the liquid crystal panel 10 are sandwiched by two sandwiching members 71 and 72, and one sandwiching member 72 is fixed to the fixture 25 by screws 57. Thereby, the relative position of the liquid crystal panel 10 and the backlight 20 does not fluctuate.

  Thus, there is no stress acting on the optical sheet 30, and the optical sheet 30 is disposed in a free state. Therefore, the optical sheet 30 expands due to the heat generated by the light emission of the CCFL 40, but the optical sheet 30 is not wrinkled because it is in a free state.

  In addition, even if the size of the optical sheet 30 is increased with the increase in the screen size, the optical sheet 30 is arranged in a curved state in the horizontal direction, so that the strength of the optical sheet 30 is improved. The occurrence of buckling can be prevented.

  In the present embodiment, a description has been given of a mode in which the fixture 25 is attached to the peripheral edge of the backlight chassis 21 and the groove 27 is formed. However, the backlight chassis 21 in which a groove is formed in the peripheral edge in advance. May be used.

  Moreover, although the form in which the optical sheet 30 is arranged in a free state has been described, the optical sheet 30 may be fixed. However, in that case, it is only necessary to lightly press the optical sheet 30, and it is not necessary to carry out with high strength unlike the conventional case.

  Further, although the optical sheet 30 has been described with respect to the horizontal direction in which the central portion is curved in the direction of the CCFL 40, the central portion of the optical sheet may be curved in the direction of the liquid crystal panel 10, and the liquid crystal It is determined appropriately according to the usage of the display device.

  Further, the direct type backlight 20 in which a plurality of CCFLs 40 as a light source are juxtaposed has been described. However, the CCFL is disposed on the side of the backlight chassis, and light emission from the CCFL is performed using a light guide plate such as an acrylic resin. Thus, the present invention can also be applied to a side-type backlight that emits light from a light emitting surface, and the same effect can be achieved by arranging the curved optical sheet 30 on the light emitting surface side.

It is a perspective view which shows the external appearance of the liquid crystal display device which concerns on this invention. 1 is a perspective view showing a configuration of a liquid crystal display device according to the present invention. It is sectional drawing in the III-III line of FIG. It is sectional drawing in the IV-IV line of FIG. It is a figure which shows the state at the time of the thermal expansion of the optical sheet in the backlight which concerns on this invention. It is principal part sectional drawing of the other backlight which concerns on this invention. It is principal part sectional drawing of the liquid crystal display device which concerns on this invention.

Explanation of symbols

10 LCD panel 20 Backlight 21 Backlight chassis (box)
21a Convex 25 Fixing tool (frame)
25a convex part 26a 1st opening part 26b 2nd opening part 27 groove | channel 30 optical sheet 30a, 30b convex part 40 CCFL (light source)

Claims (5)

In a liquid crystal display device comprising: a liquid crystal panel; a backlight having one or more light sources on the back side of the liquid crystal panel; and an optical sheet provided in a gap between the liquid crystal panel and the backlight.
The liquid crystal display device, wherein the optical sheet is arranged on the backlight in a curved state. The light source is provided in a rectangular parallelepiped box having an opening on the liquid crystal panel side,
The edges on the opening side of the two opposing side walls of the box have a curved shape,
The liquid crystal display device according to claim 1, wherein the optical sheet is curved by disposing an end portion of the optical sheet along the curved surface shape. A frame having a first opening having an area smaller than the area of the optical sheet and a second opening having an area deeper than the thickness of the optical sheet and larger than the area of the optical sheet;
The liquid crystal display device according to claim 2, wherein the frame is fixed to a peripheral edge of the box with the optical sheet being disposed in the second opening. The optical sheet has a first protrusion on the front surface or the back surface,
The box or the frame has a second protrusion corresponding to the first protrusion,
The liquid crystal display device according to claim 3, wherein a movement range of the optical sheet is regulated by the first convex portion and the second convex portion. The liquid crystal display device according to any one of claims 1 to 4, wherein the optical sheet has a central portion that is curved in the direction of the light source.

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