JP2003222862A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device having an excellent appearance, in which light irregularities and problems in terms of the appearance are eliminated by preventing an optical sheet from being bitten into a frame joining part and being positionally deviated in a back light unit, and the occurrence of chipping dust is prevented by preventing the chipping at a frame end part caused by a liquid crystal panel when disposing the panel. <P>SOLUTION: The liquid crystal display device 1 comprises: the liquid crystal panel 2; and a back light unit 3 composed of a surface light source 5 comprising a tubular light source 12 and a light guide plate 10, a frame 7 holding the surface light source, the optical sheet 6 and a reflection sheet 9. In the device 1, a wall surface positioned above the installation surface of the optical sheet 6 is formed at the opening peripheral edge on the liquid crystal panel side of the frame 7 holding the surface light source 3 and the end edge of the optical sheet is abutted to the wall surface and arranged. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a structure related to a liquid crystal panel and its backlight unit.

[0002]

2. Description of the Related Art Flat panel display devices such as liquid crystal display devices are widely used as image display devices for televisions, various computers, car navigation systems, etc., due to their features such as thinness, light weight and low power consumption.

A light transmission type liquid crystal display device includes a liquid crystal panel having a liquid crystal layer held between a pair of transparent substrates,
The backlight unit is a surface light source device that is arranged on the back side of the liquid crystal panel and guides light source light to the liquid crystal panel.

In order to further reduce the thickness and size of such a liquid crystal display device, it is necessary to reduce the thickness of the flat light source device. Under these circumstances, the surface light source device should be a direct type. The side light (edge light) system is being replaced.

In the side light type surface light source device, for example, as disclosed in Japanese Utility Model Laid-Open No. 63-24529, the light guide plate is made of an acrylic resin or the like having a milky white scattering pattern printed on the back side. The light source light from the tubular light source is made of a thin plate, enters from the side edge of the light guide plate, propagates in the light guide plate, and is emitted from the light guide plate surface on the liquid crystal panel side while being scattered by the scattering pattern on the back surface of the light guide plate.

Since the tubular light source emits the light source light to the entire circumference of the light emitting surface, a reflecting member is arranged to guide the light emitted in a direction other than the light guide plate side to the side end face side of the light guide plate. It

In such a conventional liquid crystal display device, as shown in FIG. 11, a tubular light source (72) has an end face of a light guide plate (70) and an upper frame (68) and a lower frame (67) made of resin.
It is housed in a side space (71) having a substantially U-shaped cross section formed between the inner surface of the light source plate and the inner surface of the light guide plate (70) and covers the lower surface of the light guide plate (70) on the lower surface side of the tubular light source (72). (69) is located.

The reflecting sheet (69) is formed of a film having a metal layer on its surface, and also serves as a lamp cover for protecting the tubular light source (72) by bending one end thereof.

An optical sheet (66) formed by superposing a diffusion sheet and a prism sheet is arranged on the upper surface side of the light guide plate (70), and the edge portion of the optical sheet (66) is placed at the upper frame (68).
It is located between the inner surface of and the upper bent extension end of the reflection sheet (69). The lower surface of the edge of the optical sheet (66) is black-printed, which allows the light from the tubular light source (72) to leak directly to the display side, thereby causing bright lines on the display surface of the flat display device. It prevents it from happening.

[0010]

In the above surface light source device,
The upper frame (68) and the lower frame (67) of the backlight unit are separated, and after disposing the optical sheet (66) on the surface of the light guide plate (70), the upper frame (68) and the lower frame (67) are covered to cover the lower frame (67). When installing and coupling the upper frame (68) on the upper surface of the, the edge of the upper frame (68) comes into contact with the edge of the optical sheet (66) and moves it to form the lower frame (67). The end surface of the optical sheet (66) may be caught in the joint surface or the position may be displaced.

When the end surface of the optical sheet (66) is caught or misaligned, a gap without the optical sheet (66) is formed on the opposite side of the upper frame (68), causing unevenness of light and appearance. There was a problem that got worse.

When the liquid crystal panel (62) is mounted on the upper frame (68) of the backlight unit, the end face of the liquid crystal panel (62) made of glass causes the upper frame (68) made of synthetic resin. There is a problem in that the inner corners may be shaved, the shavings of the frame enter the inside of the frame (68), and the presence of dust on the surface of the liquid crystal panel (62) is noticeable at the time of lighting.

The present invention has been made by paying attention to the above points, and prevents the optical sheet in the backlight unit from being caught in the frame joint portion or displaced, thereby eliminating unevenness in light and appearance problems. Is intended. Another object of the present invention is to provide a liquid crystal display device in which the edge of the frame is prevented from being peeled off by the panel when the liquid crystal panel is provided, the generation of shavings is prevented and the appearance is improved.

[0014]

In order to solve the above problems, the invention of a liquid crystal display device according to claim 1 is a liquid crystal panel, a surface light source including a tubular light source and a light guide plate, and a frame for holding the surface light source. In a liquid crystal display device comprising a backlight unit composed of an optical sheet and a reflection sheet, a wall surface located above the installation surface of the optical sheet is formed at the peripheral edge of the opening of the frame holding the surface light source on the liquid crystal panel side, The invention is characterized in that the edge of the optical sheet is arranged so as to abut against this wall surface, and the invention according to claim 2 projects inward at the peripheral edge of the opening of the frame holding the surface light source on the liquid crystal panel side. A collar portion is formed, and the end edge of the optical sheet is inserted between the protruding collar and the surface light source, and is arranged so as to abut against the inner surface of the outer wall of the frame.

With this configuration, the installation position of the optical sheet can be reliably determined, and the optical sheet can be prevented from being caught in the joint portion when the optical sheet is installed on the lower frame and the positional deviation. You can

A liquid crystal display device according to a third aspect of the present invention includes a liquid crystal panel, a surface light source including a tubular light source and a light guide plate, a frame for holding the surface light source, a backlight unit including an optical sheet and a reflection sheet. In a liquid crystal display device consisting of, a part of the outer peripheral edge of the optical sheet is extended outward, and the extended projection piece is provided on the inner peripheral edge of the liquid crystal panel side of the liquid crystal panel side of the frame holding the surface light source. The invention is characterized in that it is interposed between the side wall and the peripheral side wall. Similarly, in the invention according to claim 4, a part of the outer peripheral edge of the reflection sheet is extended outward and the extension is also performed. It is characterized in that the projecting piece is interposed between the inner peripheral edge of the opening on the liquid crystal panel side of the frame holding the surface light source and the peripheral side wall of the liquid crystal panel.

With this structure, since the optical sheet or the extension projection of the reflection sheet is interposed between the side edge of the liquid crystal panel and the inner wall of the frame, it is possible to position the optical sheet. It is possible to prevent the occurrence of the, and when installing the liquid crystal panel on the frame of the backlight unit, the end face of the glass liquid crystal panel does not scrape the inside of the synthetic resin frame, and the shavings are put inside the frame. It can be prevented from entering.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will now be described with reference to the accompanying drawings, FIG. 1 which is a perspective view in which a part of a liquid crystal display device such as a computer is cut away, and FIG. 2 which is a longitudinal sectional view. explain.

The liquid crystal display device (1) has a liquid crystal panel body (2) in which a plurality of pixels are arranged in a display area other than the peripheral portion.
And a bezel cover (4) for holding the backlight unit (3) and the liquid crystal panel main body (2) which are arranged on the lower side of the back surface of the liquid crystal panel main body (2) from the outside.

The backlight unit (3) comprises a surface light source (5), an optical sheet (6) arranged on this emission surface, and a lower frame (7) and an upper frame (8) for holding and housing these. The bottom surface of the lower frame (7) formed in the shape of a shallow tray is provided with a reflection sheet (9) over almost the entire surface.

The reflection sheet (9) comprises a reflection film made of a light-reflecting material such as a polycarbonate resin having a high reflectance, a conductive layer made of a conductive material such as aluminum, and PET.
It has a three-layer structure in which a film and a film are sequentially laminated, and the upper surface forms a reflector surface.

The upper surface of the light guide plate (10) is covered with the optical sheet (6). The optical sheet (6) is a sheet in which a diffusion sheet and two prism sheets are superposed on each other, and the prism sheet is densely arranged so that a large number of fine projections having a substantially equilateral triangle cross section cover the upper surface. , The parallel striped ridges are superposed so as to be orthogonal to each other.

The prism sheet has a function of converging the light emitted upward from the light guide plate (10) in the perpendicular direction of the liquid crystal panel (2) right above by the prism structure by the delicate projections, and the liquid crystal. The diffusion sheet has the effect of improving the brightness in the front direction of the display device (1) and reducing the power consumption of the surface light source.
By increasing the uniformity of the light source light emitted from the upper surface of the above in the emission surface, the variation in brightness is reduced.

On the other hand, the surface light source (5) is a liquid crystal panel (2).
A light guide plate (10) having a surface area almost equal to that of the light guide plate (10), and along one end face of the light guide plate (10) on the long side, one side wall of the lower frame (7) and an upper part thereof projecting inward to integrally form A tubular light source (12) composed of a cold cathode tube, which is arranged by accommodating an inner surface of the flange portion (7a) formed in an approximately U-shaped storage space (11). One end extension of (9) is arranged so as to cover the outer periphery of the tubular light source (12) excluding the light guide plate (10) side.

As is apparent from FIG. 1, the optical sheet (6) has an edge extending from the edge of the light guide plate (10) to a position above the tubular light source (12) to protect it. It is arranged so as to cover the lower surface side of the flange portion (7a) of the frame (7).

The bezel cover (4) is an outer frame formed by forming a metal sheet member having an inverted L-shaped cross section into a frame shape, and covers the lower frame (7) and the upper frame (8) with screws or the like. By fixing, the liquid crystal panel (2) and the backlight unit (3) are integrally connected.

However, when assembling the backlight unit (3), the following working procedure is carried out. First, the reflection sheet (9) is laid inside the lower frame (7), and the collar portion (7a) provided on one side of the lower frame (7).
The tubular light source (12) is installed in the U-shaped storage space (11) formed by the above, the terminals thereof are connected, and the light guide plate is provided on the reflection sheet (9) in the side space of the tubular light source (12). Store and arrange (10).

Next, the light guide plate (1) in the lower frame (7) is
The optical sheet (6) is laid on the surface of (0). At this time,
The optical sheet (6) is a collar portion (7a) of the lower frame (7).
It is inserted into a gap (15) formed between the lower U-shaped space and the light guide plate (10) and is arranged so as to abut against the inside of the outer wall of the frame (7). The flange shape is not provided on the three sides of the lower frame other than the one side where the flange portion (7a) is formed, but a locking projection (7b) slightly protruding inward from the upper end edge is provided on the peripheral edge. It is provided to prevent the optical sheet (6) from being lifted up in the frame (7).

Above the lower frame (7) on which the reflection sheet (9), the tubular light source (12), the light guide plate (10) and the optical sheet (6) are arranged, the tubular light source (12) side is excluded. An upper frame (8) composed of frame-shaped three sides is installed.

This upper frame (8) is taken along the line A--A in FIG.
As shown in FIG. 3 which is a cross-section taken along the line and FIG. 4 which is a schematic overall view, a collar portion (which receives the peripheral portion of the liquid crystal panel (2) and the upper portion having substantially the same cross-sectional shape as the upper portion of the lower frame (7) ( 8a), the lower peripheral portion is engaged with a concave groove (7c) formed on the upper surface of the peripheral portion of the lower frame (7), and an engaging hole (8b) is formed in the lower central portion of each side. An engaging claw (8c) is formed, and the engaging hole (8b) and the engaging claw (8c) are provided with an engaging projection (7d) and an engaging recess (7e) provided on the upper surface of the corresponding lower frame (7). ), The upper frame (8) is attached to the lower frame (7), and the backlight unit (3) integrally incorporating these is completed.

As described above, when the optical sheet (6) is installed on the light guide plate (10), the optical sheet (6) is placed on the inner surface of the outer wall of the U-shaped space (11) in the lower frame (7). Since the end edges of the optical sheet are abutted against each other for positioning, the installation position of the optical sheet (6) on the light guide plate (10) is stabilized, and thereby the position is not displaced. Therefore, conventionally, when the upper frame is attached, the edge of the upper frame comes into contact with the edge of the optical sheet (6) that is installed in a displaced position, whereby the optical sheet (6) moves,
It is possible to prevent the edge from being caught in the joint portion with the lower frame (7), and it is possible to prevent misalignment, uneven light due to misalignment, and appearance problems.

In the above embodiment, the flange portion (7a) is formed on the lower frame (7) on the side where the tubular light source (12) is installed, and the upper frame is integrated, but the same portion is formed. As shown in FIG. 5 with reference numerals, the frame structure is divided into an upper frame (18) and a lower frame (17) as in the conventional case, and the upper edge (1) of the lower frame (17) is surrounded.
7) is positioned above the surface of the optical sheet (6) placed on the light guide plate (10), and when the optical sheet (6) is installed, the optical sheet (6) is placed on the outer wall surface of the lower frame (17). It may be arranged so as to abut, and then the four-sided frame-shaped upper frame (18) may be engaged and installed on the lower frame (17).

In this case as well, the optical sheet (6) can be positioned by abutting against the inner surface of the outer wall of the lower frame (17), and the optical sheet (6) can be positioned between the upper frame (18) and the lower frame (17). It is possible to prevent the optical sheet (6) from being caught in the joint surface.

Next, another embodiment of the present invention will be described.
As shown in FIG. 6 and FIG. 7 which is a perspective view of the backlight unit with the same reference numerals as in the above embodiment, along the outer wall near the corner portion on the long side of the lower frame (27),
A perforation hole (27b) having a predetermined width is formed in the upper collar portion (27a) on which the optical sheet (26) is laid, and the collar portion (27) of the optical sheet (26) laid inside the lower frame (27).
An extension protrusion (26a) is provided at a position corresponding to the through hole (27a) at the edge on the side a), and the protrusion (26a) is protruded from the through hole (27a) by a predetermined length. I am letting you.

With this structure, the extension projection piece (26a) of the optical sheet is interposed between the edge of the liquid crystal panel (2) and the lower frame (27), and the optical sheet ( The position of the liquid crystal panel (2) is made of glass when the liquid crystal panel (2) is mounted on the frame (27) of the backlight unit while the position of the liquid crystal panel (26) can be positioned. With this, the inside of the synthetic resin frame (27) is no longer shaved, the shavings of the frame (27) can be prevented from entering the frame, and the presence of dust is noticeable from the surface when the liquid crystal panel (2) is turned on. Can be prevented.

Further, as shown in FIG. 8, when the upper frame (38) and the lower frame (37) are formed separately, the extension protrusion (36a) of the optical sheet (36) is previously attached to the upper frame (38). ) Is held by penetrating through the through hole (38b) of the collar portion (38a), and the combined body of the upper frame (38) and the optical sheet (36) is provided with the light guide plate (10) and other lower frames. (37) It may be placed on and engaged with.

In the above embodiment, the lower frame (3
Although the extension projection piece (36a) of the optical sheet is projected from the through hole (38b) of the predetermined width of 7), as shown in FIG. 9, the reflection sheet (49) of the reflection sheet (49) laid on the bottom surface of the lower frame (47). An extension piece (46a) is provided by extending a part of the end face, and this is provided with a flange (47a).
It may be made to project upward from the through hole (47b) of a) so as to be interposed between the liquid crystal panel (2).

A through hole (47b) through which the extension piece projects
Is not limited to the through hole (47b) having the predetermined width as in the above embodiment, and although not particularly shown, the through hole is extended to the corner portion to form an L-shaped elongated hole, which is an extension of the optical sheet protruding upward. The area of the protrusion may be increased to reduce interference when the liquid crystal panel is mounted on the lower frame.

Also in the above-mentioned embodiment, as described above, the flange portion (47a) having the through hole (47b) is provided not in the lower frame (47) but in the upper frame formed separately from the lower frame. It goes without saying that it is okay.

Further, as shown in a perspective view in which the upper and lower frames are partially cut out in FIG. 10, several small protrusions (57a) are formed inward from the lower frame (57), and a liquid crystal panel (not shown) adjacent to this is formed. The chance of contact between the frame and the frame (57) may be minimized to prevent the generation of shavings.

[0041]

As described above, according to the first aspect of the present invention, the installation position of the optical sheet in the frame of the liquid crystal display device can be determined with certainty, and when the optical sheet is installed in the upper frame to the lower frame. It is possible to prevent the optical sheet from being caught in the joint part and to eliminate misalignment.
The appearance can be maintained well.

According to the second aspect of the invention, it is possible to more reliably prevent the positional deviation and the biting of the optical sheet.

According to the inventions of claims 3 and 4,
Between the side edge of the liquid crystal panel and the inner wall of the frame, an optical sheet or an extension projection of the reflection sheet is interposed, so that the optical sheet can be positioned and the occurrence of displacement can be prevented. When installing the liquid crystal panel on the frame of the backlight unit, it is possible to prevent shavings from entering the inside of the frame because the inside of the frame made of synthetic resin is not scraped off by the end face part of the liquid crystal panel made of glass, It is possible to prevent the problem that dust is conspicuous from the surface when the liquid crystal panel is turned on.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a detailed sectional view of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a schematic overall view of a backlight unit.

FIG. 5 is a sectional view of the same portion as FIG. 2 showing another embodiment of the present invention.

FIG. 6 is a sectional view of the same portion as FIG. 2 showing another embodiment of the present invention.

FIG. 7 is a perspective view of the backlight unit in FIG.

8 is a cross-sectional view showing a modified example of FIG.

FIG. 9 is a sectional view showing still another embodiment of the present invention.

FIG. 10 is a perspective view showing a modified example of FIG. 9.

11 is a cross-sectional view of the same portion as FIG. 2 showing a conventional example.

[Explanation of symbols]

1 ... Liquid crystal display device 2 ... Liquid crystal panel 3 ... Backlight unit 4 ... Bezel cover 5
Surface light source 6 Optical sheet 7 Lower frame 7a
Collar 7b ... Locking projection 7c ... Recessed groove 7d ... Engaging projection 7e ... Engaging recess 8 ... Upper frame 8a ... Collar 8b ... Engaging hole 8c ... Engaging claw 9 ... Reflecting sheet 10 ... Light guide plate 11 ... Storage space 12 ... Tubular light source 15 ... Gap

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1333 G02F 1/1333 // F21Y 103: 00 F21Y 103: 00

Claims (4)

[Claims] 1. A surface light source comprising a liquid crystal panel, a surface light source including a tubular light source and a light guide plate, a frame for holding the surface light source, and a backlight unit including an optical sheet and a reflection sheet. A liquid crystal display device characterized in that a wall surface located above the installation surface of the optical sheet is formed on the periphery of the opening of the frame for holding the liquid crystal panel, and the edge of the optical sheet is abutted against this wall surface. . 2. A frame outer side wall is formed by forming an inwardly projecting brim portion at a peripheral edge of an opening of a frame for holding the surface light source on the liquid crystal panel side, and inserting an edge of the optical sheet between the projecting brim and the surface light source. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is arranged so as to abut against an inner surface of the liquid crystal display device. 3. A liquid crystal display device comprising a liquid crystal panel, a surface light source composed of a tubular light source and a light guide plate, a frame holding the surface light source, a backlight unit composed of an optical sheet and a reflection sheet. A part of the outer peripheral edge is extended outward, and the extending projecting piece is interposed between the inner peripheral edge of the liquid crystal panel side opening of the frame holding the surface light source and the peripheral side wall of the liquid crystal panel. Liquid crystal display device characterized by. 4. A liquid crystal display device comprising a liquid crystal panel, a surface light source including a tubular light source and a light guide plate, a frame for holding the surface light source, a backlight unit including an optical sheet and a reflection sheet, and A part of the outer peripheral edge is extended outward, and the extending projecting piece is interposed between the inner peripheral edge of the liquid crystal panel side opening of the frame holding the surface light source and the peripheral side wall of the liquid crystal panel. Liquid crystal display device characterized by.