JPH1184351A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of installing optical sheets at prescribed positions accurately and also capable of narrowing a picture frame. SOLUTION: The back light unit 12 of a liquid crystal display device is provided with a light transmission plate 26 and optical sheets 28, 30 overlapped and arranged on both surfaces of the light transmission plate 26. Two pairs of positioning protrusions 40a, 42a are formed in the non-luminous area of the plate 26 and positioning holes 28a, 28b, 30a, 30b respectively opposed to the positioning protrusions are formed in respective optical sheets 28, 30. Respective optical sheets are positioned with respect to the light transmission plate 26 by engaging the positioning protrusions with the positioning holes.

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 liquid crystal display having an edge lamp type back light source (hereinafter referred to as a side light) and optical sheets such as a reflection sheet, a diffusion sheet, and a prism sheet. It relates to a display device.

[0002]

2. Description of the Related Art For example, electronic equipment having a liquid crystal display device such as a portable personal computer is desired to be reduced in size and weight due to its properties, and it is desired that the area of a display screen is further enlarged. I have. In order to respond to these conflicting demands, the liquid crystal display device has been improving its driving circuit, its packaging technology, and its structure. Against this background, a structure called a narrow frame liquid crystal display device or the like in which the distance between the edge of the liquid crystal display screen and the edge of the liquid crystal display device is about several mm has been required.

Here, focusing on the backlight unit, which is an important factor in determining the structure of the liquid crystal display device, usually, in the backlight unit, a reflection sheet is provided below the light guide plate, and the reflection sheet is provided on the light emitting surface side. A plurality of sheets, such as a diffusion sheet and a prism sheet, are provided for the purpose of controlling light emission characteristics.

[0004] The light guide plate disposed on the liquid crystal display panel is 1.5 to 2.0 mm from the periphery of the display area of the liquid crystal display panel.
mm, and the optical sheets are
The light guide plate is attached to a non-light-emitting area located in a range of 1.5 to 2.0 mm in the peripheral portion, or is attached to a structural component holding the light guide plate, and is arranged at a predetermined position. .

[0005]

However, as described above, as the frame of the liquid crystal display device is reduced, the non-light emitting area of the light guide plate is also reduced, and the area where the optical sheets are attached is becoming smaller. Therefore, it is difficult to securely fix the optical sheet. In addition, when attaching optical sheets, it is necessary to consider thermal expansion. That is, the optical sheet may be distorted or warped due to a difference in thermal expansion between the optical sheet and the support frame supporting the optical sheet, which may cause a problem in optical characteristics.

Conventionally, in order to prevent distortion of the optical sheet due to thermal expansion, the place where the optical sheet is attached is limited, or the optical sheet is not fixed, and the peripheral edge of the optical sheet enters the frame of the liquid crystal display device. An installation method is adopted in which a storage space is formed, and the periphery of the optical sheet is dropped into the storage space.

However, a certain gap is required between the storage space in which the optical sheet enters and the outer shape of the optical sheet. If the gap increases with the increase in the screen size of the liquid crystal display device, the optical sheet tends to be offset. Becomes

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid crystal display device in which an optical sheet can be accurately set at a predetermined position and a frame can be narrowed.

[0009]

In order to achieve the above object, a liquid crystal display device according to the present invention includes a liquid crystal display panel, and a light source unit disposed opposite to the liquid crystal display panel. The light source unit includes a support frame, a tubular light source, a light guide plate mounted on the support frame facing the liquid crystal display panel, and guiding light from the light source, and an optical sheet disposed on the light guide plate. And The light guide plate includes a positioning portion that engages with the optical sheet and positions the optical sheet with respect to the light guide plate.

According to the above liquid crystal display device, the optical sheet is disposed so as to be positioned at a predetermined position with respect to the light guide plate by engaging with the positioning portion of the light guide plate. In this case, there is no need to attach the optical sheet to the light guide plate or the support frame, or to insert the peripheral edge of the optical sheet into the recess of the support frame. Can be narrowed.

According to the present invention, the positioning section has the positioning projection protruding from the light guide plate, and the optical sheet has the positioning hole with which the positioning projection is engaged. The positioning protrusions are provided at, for example, two places, and the diameter of each protrusion is, for example, φ.
In the case of 1, the diameter of the positioning hole of the optical sheet is about φ1.2 and a long hole of about φ1.2 × 2 is used to absorb the difference in thermal expansion between the optical sheet and the light guide plate. .

Further, a liquid crystal display device according to the present invention includes a liquid crystal display panel, and a backlight unit provided to face the liquid crystal display panel, wherein the backlight unit includes a support frame, A light source supported by the support frame; a light guide plate mounted on the support frame to face the liquid crystal display panel and guiding light from the light source; and an optical sheet disposed to overlap the light guide plate. doing. The support frame includes a positioning portion that engages with the optical sheet and the light guide plate and positions the optical sheet with respect to the light guide plate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the liquid crystal display device includes a liquid crystal display panel 10 and an edge light type backlight unit 1.
2 and the holding frame 14 are laminated. The liquid crystal display panel 10 includes a rectangular array substrate 16 and a counter substrate 18, and liquid crystal molecules (not shown) sealed between these substrates. The array substrate is driven via a plurality of TCPs (tape carrier packages) 20. The circuit board 22 is connected.

As shown in FIGS. 1 to 3, the backlight unit 12 includes a support frame 24 having a rectangular plate shape, a light guide plate 26, a plurality of, for example, two optical sheets 28, 30,
A cold cathode tube 32 as a light source, a light cover 34 and the like are provided.

The support frame 24 is formed of, for example, a synthetic resin, and has a rectangular storage recess 36 formed at a position other than a peripheral portion thereof. The light guide plate 26 is made of, for example, an acrylic plate and is formed in a rectangular shape having substantially the same size as the storage recess 36. Similarly, the optical sheets 28 and 30 are also formed in a rectangular shape having substantially the same size as the storage recess 36.

The optical sheet 28 is formed of a reflection sheet, and the optical sheet 30 is formed of, for example, a prism sheet. Then, the optical sheet 28, the light guide plate 26,
The optical sheets 30 are mounted in the storage recesses 36 of the support frame 24 in a state of being stacked in this order.

The light guide plate 26 includes a positioning portion for positioning the optical sheets 28 and 30 with respect to the light guide plate 26. That is, the light guide plate 26 has the positioning protrusions 40 at both ends on the central axis along the longitudinal direction.
a, 40b, 42a, and 42b are integrally provided.

As shown in FIGS. 2 and 4, the positioning projections 40a and 42a project from one surface of the light guide plate 26, and the positioning projections 40b and 42b project from the other surface of the light guide plate 26. Then, the positioning projections 40a,
40b are coaxial with each other, and positioning protrusions 42a,
42b are provided coaxially with each other. In particular, these positioning projections 40a, 40b, 42a, 42b are provided adjacent to the periphery of the light guide plate 26, that is, in the non-light-emitting area of the light guide plate.

On the other hand, two opposing side edges of the optical sheet 28 are provided with positioning projections 40a and 42a.
And positioning holes 28a and 28b, respectively, which are respectively engaged. Positioning holes 30a and 30b are formed on two opposing side edges of the optical sheet 28 to engage with the positioning protrusions 40b and 42b, respectively.

As shown in FIGS. 2 and 5, one positioning hole 28a of the optical sheet 28 is accurately formed at a predetermined position and is opened at a side edge of the optical sheet. The other positioning hole 28b is formed as a long hole extending in the longitudinal axis direction of the optical sheet 28. The positioning holes 30a and 30b of the optical sheet 30 are similarly formed.

The positioning projections 40a, 40b, 42a, 4
When the diameter of 2b is, for example, φ1, the diameter of the positioning holes 28a, 30a of the optical sheet is formed to be about φ1.2, and the positioning holes 28b, 30b are formed as long holes having a diameter of about φ1.2 × 2.

The optical sheets 28, 30 are positioned at predetermined positions with respect to the light guide plate 26 by inserting the corresponding positioning projections 40a, 40b, 42a, 42b into the positioning holes 28a, 28b, 30a, 30b. In the positioned state, they are arranged on both sides of the light guide plate so as to overlap.

Further, engaging holes 36a and 36b are formed in the storage recess 36 of the support frame 24 in correspondence with the positioning projections 42a and 42b of the light guide plate 26. One of the engagement holes 36a and 36b is formed by a long hole, similarly to the positioning hole of the optical sheet.
The light guide plate 26 is attached to the storage recess 36 with the positioning projections 42a and 42b engaged with the engagement holes 36a and 36b of the support frame 24, respectively.
It is positioned with respect to the support frame 24 together with 8, 30.

On the other hand, the cold cathode tube 32 is mounted on the support frame 24 so as to face the long side of the light guide plate 26. As shown in FIG. 2 and FIG.
4 has a lamp accommodating groove 44 formed at the side edge of the support frame, continuing from the accommodating recess 36. Cold cathode tube 3
2 are housed in the lamp housing grooves 44,
4 extends over substantially the entire length in the longitudinal direction.

The lamp cover 34 has a substantially L-shaped cross section, and is fitted to the support frame 24 to cover the entire cold cathode tube 32. The inner surface of the lamp cover 34 is, for example,
A reflective film is formed and has a high reflectance. Further, the lamp cover 34 has a side edge 35 extending in the longitudinal direction of the support frame 24, and the side edge 35 is
8 and 30 are positioned so as to overlap the side edges of the light guide plate 26. A plurality of, for example, two positioning recesses 46 are formed on the inner surface side of the side edge 35, and are arranged apart from each other along the longitudinal direction of the light cover 34.

On the other hand, the light guide plate 26 has a pair of positioning projections 50 protruding near the side edge facing the cold cathode tube 32. These positioning projections 50 are engaged with the positioning recesses 46 of the lamp cover 34 via the optical sheet 30. Thereby, the lamp cover 34
Are mounted on the support frame 24 while being positioned with respect to the light guide plate 26. The optical sheet 28 includes
A notch 52 is formed to avoid interference with the positioning projection 50.

As shown in FIG. 1, the liquid crystal display panel 10
Is the backlight unit 12 configured as described above.
And is adjacently opposed to the optical sheet 30. Further, the holding frame 14 is formed in a rectangular frame shape, and is disposed so as to overlap the peripheral portion of the liquid crystal display panel 10. And
By fixing the holding frame 14 to the support frame 24 by screwing or the like, the liquid crystal display panel 10 is fixed to the support frame 24 while being held between the holding frame 14.

According to the liquid crystal display device configured as described above, the positioning projections 40 a and 40 provided on the light guide plate 26 are provided.
By engaging the b, 42a, 42b with the positioning holes 28a, 28b, 30a, 30b formed in the optical sheets 28, 30, respectively, the respective optical sheets are accurately positioned at predetermined positions with respect to the light guide plate, and In addition, misalignment can be prevented. The optical sheet has a simple configuration in which only a positioning hole is provided, so that a space for positioning and fixing can be reduced as compared with the case where a conventional adhesive is used. Therefore, the frame of the liquid crystal display device can be narrowed.

One of the positioning holes provided in each optical sheet is formed by a long hole extending in the longitudinal direction of the optical sheet, that is, a long hole extending in the direction away from the positioning projection. Therefore, even when a difference in thermal expansion occurs between the optical sheet, the light guide plate, and the support frame, the difference can be absorbed, and distortion and warpage of the optical sheet can be prevented. Thereby, it is possible to maintain stable optical characteristics of the optical sheet.

Further, according to the present embodiment, the cold cathode fluorescent lamp 3
The light cover 34 can be positioned at a predetermined position with respect to the light guide plate 26 by engaging the positioning protrusion 50 provided on the light guide plate 26 side with the positioning recess 46 formed in the second light cover 34.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the number of optical sheets is not limited to two, and another optical sheet such as a diffusion sheet may be further provided. Conversely, the support frame 24 is made of, for example, 90% magnesium.
The support frame itself can be used as a reflection plate and the reflection sheet can be omitted by being formed of a synthetic resin containing a certain amount.

In the above-described embodiment, the positioning protrusions for the optical sheet and the positioning protrusions for the light cover are separately provided on the light guide plate 26. However, the optical sheet and the light cover are provided by a common positioning protrusion. May be configured.

Further, in the above embodiment, the positioning projections are provided on the light guide plate 26. However, as shown in FIG. 7, the positioning projections 60 are integrally formed in the storage recesses 36 of the support frame 24. The positioning holes 26a, 28a, and 30a that engage with the positioning protrusions may be provided in the optical sheet and the light guide plate. In this case, the same operation and effect as those of the above-described embodiment can be obtained.

[0034]

As described above in detail, according to the present invention, by providing the light guide plate or the support frame with the positioning portion that engages with the optical sheet, the optical sheet can be accurately set at a predetermined position and can be narrowed. A liquid crystal display device that can be framed can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a backlight unit in the liquid crystal display device.

FIG. 3 is a plan view of the backlight unit.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is an enlarged plan view showing portions a and b in FIG. 3;

FIG. 6 is a sectional view taken along line BB in FIG. 1;

FIG. 7 is a perspective view showing a main part of a backlight unit according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display panel 12 ... Backlight unit 14 ... Holding frame 24 ... Support frame 26 ... Light guide plate 28, 30 ... Optical sheet 32 ... Cold cathode tube 34 ... Light cover 28a, 28b, 30a, 30b, 26a ... Positioning hole 40a , 40b, 42a, 42b, 50, 60 ... positioning protrusion 46 ... positioning recess

Claims (6)

[Claims] 1. A liquid crystal display panel, comprising: a backlight unit disposed opposite to the liquid crystal display panel, wherein the backlight unit includes a support frame, a tubular light source, and a liquid crystal display panel. A light guide plate mounted opposite to the support frame to guide light from the light source; and an optical sheet disposed on the light guide plate, wherein the light guide plate is engaged with the optical sheet. A liquid crystal display device comprising a positioning portion for positioning an optical sheet with respect to the light guide plate. 2. The optical system according to claim 1, wherein the positioning portion has a positioning protrusion protruding from the light guide plate, and the optical sheet has a positioning hole with which the positioning protrusion is engaged. The liquid crystal display device as described in the above. 3. The positioning section has a pair of positioning projections projecting apart from each other in a non-light-emitting area of the light guide plate, and the optical sheet has a pair of positioning projections respectively engaged with the positioning projections. Has a hole, one of the positioning holes,
The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed in a long hole shape extending along a direction in which the positioning projections are separated from each other. 4. The backlight unit includes a cover which is mounted on the support frame so as to cover the light source, wherein the cover has a side edge overlapped with the light guide plate and the optical sheet, and the side edge. Wherein the light guide plate is provided with a positioning projection projecting from the non-light emitting area and engaging the positioning portion of the cover to position the cover. The liquid crystal display device according to claim 1. 5. A liquid crystal display panel, comprising: a backlight unit disposed to face the liquid crystal display panel, wherein the backlight unit includes a support frame, a tubular light source, and a liquid crystal display panel. A light guide plate, which is attached to the support frame to face and guides the light from the light source, and an optical sheet disposed so as to overlap the light guide plate, wherein the support frame includes the optical sheet and the light guide plate. A liquid crystal display device comprising a positioning portion that engages and positions an optical sheet with respect to the light guide plate. 6. The optical system according to claim 6, wherein the positioning portion has a positioning projection protruding from the support frame, and the optical sheet and the light guide plate have a positioning hole with which the positioning projection is engaged. Item 6. A liquid crystal display device according to item 5.