JP5650005B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device having a flat light emitting surface.

  FIG. 4 schematically shows a cross-sectional configuration of a conventional transmissive or transflective liquid crystal display device. As shown in the figure, a reflection plate 15, a light guide plate 14, a diffusion plate 18, a prism sheet 17, a prism sheet 16, and the liquid crystal panel 1 are arranged inside the resin frame 2 so as to overlap each other. The outside of the resin frame 2 is covered with a metal frame 3. Here, the three components of the resin frame 2, the prism sheet 16, and the liquid crystal panel 1 are held by the double-sided tape 6 (see, for example, Patent Document 1).

JP 2008-234963 A

  However, in the configuration described in Patent Document 1, as shown in FIG. 4, the end surface of the optical sheet (diffuser plate 18, prism sheet 16, 17) is separated from the boundary line 4 of the effective display range (active area) of the liquid crystal panel. I can't keep away. That is, the distance D1 from the end face of the optical sheet to the boundary line 4 of the effective display range is short. For this reason, when the liquid crystal display device is viewed obliquely, the light irregularly reflected by the end face of the optical sheet enters the effective display range of the liquid crystal panel, and a bright line phenomenon that looks like a line of light occurs. The bright line is indicated by “S” in the figure.

  In addition, since the resin frame 2, prism sheet 16, and liquid crystal panel 1 having different thermal expansion coefficients are fixed with double-sided tape, the prism sheet 16 swells and wrinkles when exposed to high temperature and high temperature and high humidity. There is a risk.

  Therefore, in order to solve the above problems, a resin frame that accommodates the liquid crystal panel and the backlight is composed of a first frame portion that holds the liquid crystal panel and a second frame portion around the backlight, and the liquid crystal panel and the backlight. The optical sheet provided between the first frame portion and the second frame portion is extended to a gap formed therebetween. Further, the optical sheet is accommodated between the first frame portion and the second frame portion without being held by any component.

  Here, “holding” means fixing two or more parts using a double-sided tape or the like.

  According to the present invention, since the end surface of the optical sheet can be sufficiently distant from the effective display range of the liquid crystal panel, the light irregularly reflected by the end surface of the optical sheet enters the effective display range of the liquid crystal panel, The visible bright line phenomenon does not occur.

1 is a plan view of a liquid crystal display device of Example 1. FIG. 3 is a schematic diagram illustrating a cross-sectional configuration of the liquid crystal display device of Example 1. FIG. 6 is a schematic diagram illustrating a cross-sectional configuration of a liquid crystal display device of Example 2. FIG. It is a schematic diagram explaining the cross-sectional structure of the conventional liquid crystal display device.

  The liquid crystal display device of the present invention includes a liquid crystal panel, a backlight that illuminates the liquid crystal panel, a resin frame that houses the liquid crystal panel and the backlight, a metal frame that supports the resin frame, and a liquid crystal panel and the backlight. An optical sheet is provided. Here, the resin frame includes a first frame portion for holding the liquid crystal panel and a second frame portion around the backlight, and an optical sheet extends in a gap formed by the first frame portion and the second frame portion. ing. With such a configuration, a distance from the end face of the optical sheet to the effective display range of the liquid crystal panel can be ensured, and light irregularly reflected by the end face of the optical sheet can be prevented from entering the effective display range.

Furthermore, the optical sheet was accommodated between the first frame part and the second frame part and between the backlight and the liquid crystal panel without being held by any part. Therefore, undulations and wrinkles are unlikely to occur on the optical sheet. The first frame part and the second frame part may be separate parts.
Examples according to the present invention will be specifically described below.

  FIG. 1 is a plan view for explaining the liquid crystal display device according to the first embodiment. The liquid crystal panel 1 is held inside the resin frame 2. The outer periphery and bottom surface of the resin frame 2 are covered with a metal frame 3. An FPC 5 is connected to one side of the liquid crystal panel 1. Characters and images are displayed in a region inside the boundary line 4 of the effective display range indicated by a one-dot chain line in the figure.

  FIG. 2 shows an enlarged cross-sectional shape taken along line AB in FIG. A reflection plate 15 is disposed on the bottom surface of the metal frame 3, and a light guide plate 14 is disposed above the reflection plate 15. A second resin frame 8 is disposed between the light guide plate 14 and the metal frame 3. The reflection plate 15 is held on the second resin frame 8 by the double-sided tape 9. The resin frame 2 having the stepped portion 7 is supported by the metal frame 3, and a gap is formed between the resin frame 2 and the second resin frame 8. A diffusion plate 18, a prism sheet 17, and a prism sheet 16 are disposed above the light guide plate 14. Hereinafter, the diffusion plate 18, the prism sheet 17, and the prism sheet 16 are collectively referred to as an optical sheet. That is, the optical sheet may include other sheets or may be any one sheet. These optical sheets are accommodated between the resin frame 2 and the second resin frame 8. At this time, the optical sheet is not held in any part by a double-sided tape or the like, and is in a state where it can freely expand and contract. A liquid crystal panel 1 is disposed above the optical sheet. In this embodiment, the liquid crystal panel 1 includes an upper deflection plate 10, an upper glass 11, a liquid crystal layer, a lower glass 12, and a lower deflection plate 13. In FIG. 2, the stepped portion 7 of the resin frame 2 and the lower glass 12 of the liquid crystal panel 1 are bonded by the double-sided tape 6.

  Thus, a gap was provided between the resin frame 2 and the second resin frame 8, and the optical sheet was accommodated in this gap. For this reason, the distance “D2” from the end face of the optical sheet to the boundary line 4 of the effective display range of the liquid crystal panel 1 can be sufficiently secured, and light diffusely reflected by the end face of the optical sheet is prevented from entering the effective display range. it can. Here, it is desirable to set “D2” so as to satisfy the following expression.

D2> (total thickness of upper deflection plate 10 + upper glass 11 + lower glass 12) / (tan 45 °)
Furthermore, according to the above-described configuration, the optical sheet can be disposed between the liquid crystal panel and the light guide plate without being held by any member. Therefore, the optical sheet can freely expand and contract. Therefore, even if it expands once in a high temperature and high temperature and high humidity environment, it will shrink to its original shape when it returns to a normal temperature environment. On the other hand, when the liquid crystal panel 1 and the resin frame 2 having different thermal expansion coefficients are held as in the prior art, the optical sheet that has once expanded cannot shrink to the original shape, and undulations and wrinkles are generated. Usually, a thin optical sheet is used to reduce the total thickness of the liquid crystal display device. In particular, when the diagonal length of the effective display range is 4 inches or less, an optical sheet having a thickness of 40 to 70 μm is used. When the optical sheet becomes thin or has a large area, undulations and wrinkles are likely to occur.

  The resin frame 2 and the second resin frame 8 are made of a resin such as polycarbonate by injection molding. The metal frame 3 is made of a metal material having good formability such as an aluminum material or a stainless material. Since the material thickness of the metal frame 3 is also included in the total thickness of the liquid crystal display device, a relatively thin material of 100 to 300 μm is used. The resin frame 2, the second resin frame 8, and the metal frame 3 can be integrally molded by a technique called insert molding. The resin frame 2 is disposed between the liquid crystal panel 1 and the metal frame 3 and also serves as a buffer material for the liquid crystal panel 1 that is easily broken. The second resin frame 8 is disposed between the light guide plate 14 and the metal frame 3, and returns light leaked from the side surface of the light guide plate 14 to the light guide plate 14 in addition to serving as a buffer material for the light guide plate 14 that is easily damaged. Also, it plays a role of increasing the luminance of the liquid crystal display device. Therefore, white resin with high reflectance is suitable for the resin frame 2 and the second resin frame 8.

  Further, by making the bottom surface of the resin frame 2 and the top surface of the second resin frame 8 rough, it is difficult for the diffusion plate 18 and the prism sheet 16 to be displaced, and the optical sheet can be prevented from being displaced. However, this does not restrict the expansion and contraction of the optical sheet.

  FIG. 3 is a schematic diagram for explaining a cross-sectional configuration of the liquid crystal display device according to the present embodiment. The method of holding the liquid crystal panel 1 is different from that of the first embodiment. The other configuration is the same as that of the first embodiment, and thus a duplicate description is omitted as appropriate. As shown in FIG. 3, in this embodiment, the liquid crystal panel 1 is held by a protruding structure 19 provided on the resin frame 2. The liquid crystal panel 1 is held by pressure from above. Since the double-sided tape that holds the liquid crystal panel 1 is not used, the number of parts can be reduced. The protrusion structure 19 that holds the liquid crystal panel 1 is not limited to the shape shown in FIG. 3, and may be any structure that can push the liquid crystal panel 1 from above.

  Since it is a liquid crystal display device, it can be applied to electronic devices such as mobile phones and digital cameras with display surfaces.

1 LCD panel 2 Resin frame 3 Metal frame 4 Effective display range boundary 5 FPC
6 Double-sided tape 7 Stepped portion 8 Second resin frame 9 Double-sided tape 10 Upper deflection plate 11 Upper glass 12 Lower glass 13 Lower deflection plate 14 Light guide plate 15 Reflecting plate 16, 17 Prism sheet 18 Diffusing plate 19 Projection structure

Claims (5)

LCD panel,
A backlight for illuminating the liquid crystal panel;
A resin frame for housing the liquid crystal panel and the backlight;
A metal frame that supports the resin frame;
An optical sheet provided between the liquid crystal panel and the backlight, and a liquid crystal display device comprising:
The resin frame and a second frame portion of the periphery of the backlight and the first frame portion for holding the liquid crystal panel,
The optical sheet is extending gap between said first frame portion and the second frame portion is formed,
The liquid crystal display device , wherein the gap is formed up to an outer periphery of the first frame part and the second frame part .   The liquid crystal display device according to claim 1, wherein the optical sheet is accommodated between the first frame portion and the second frame portion without being held by any component.   The liquid crystal display device according to claim 1, wherein a step is formed in the first frame portion, and the liquid crystal panel is fixed to an upper surface of the step.   The liquid crystal display device according to claim 1, wherein a protrusion structure is formed on the first frame portion, and the liquid crystal panel is fixed by the protrusion structure. 5. The liquid crystal display device according to claim 1, wherein the first frame portion and the second frame portion are formed with a rough surface on the optical sheet side.

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