JP2002107715A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which light from a point light source can be properly functioned as a back light by preventing irregular luminosity of the point light source, leaking of light from the back light can be prevented and good liquid crystal display can be realized. SOLUTION: In the liquid crystal display device, a light guide body 20 to guide the light from the point light source 17 of the back light is mounted on a power supply side wiring board 16 opposing to a liquid crystal display element 10, and the liquid crystal display element 10 and the light guide body 20 are adhered with an adhesive sheet 22. A coating protruding edge 22B which can cover the corresponding end face of the light guide body 20 is formed on at least one edge of the adhesive sheet 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a backlight-integrated liquid crystal display device in which a backlight is provided between a liquid crystal display element and a power supply side wiring board.

[0002]

2. Description of the Related Art First, an example of a general liquid crystal display element in this type of liquid crystal display device will be described with reference to FIG.

FIG. 5 shows a displayable liquid crystal display element 10 mounted on a liquid crystal display device, which has two transparent substrates 1A and 1B arranged substantially in parallel at an interval. . The outer periphery between the two transparent substrates 1A and 1B is sealed by a sealing material 2, and a transparent common electrode 3A is disposed on the lower surface of one of the transparent substrates 1A located above so as to be in close contact therewith. A light-shielding film 4 is disposed below the transparent common electrode 3A so as to cover a non-display portion of the liquid crystal display element 10.

Below the light shielding film 4, an alignment film 6A for controlling the alignment of liquid crystal molecules according to the voltage applied between the electrodes.
Are disposed in close contact with each other, and a polarizing plate 7A is disposed on the upper surface of the transparent substrate 1A.

On the other hand, a transparent segment electrode 3B is disposed on the upper surface of the transparent substrate 1B located below,
A color filter film 5 is disposed above the transparent segment electrode 3B, and an alignment film 6B is disposed above the color filter film 5 so as to be in close contact therewith. Further, a polarizing plate 7B is provided on the lower surface of the transparent substrate 1B.

A liquid crystal 8 is sealed in a sealed space surrounded by the transparent substrates 1A and 1B and the sealing material 2, and a plurality of spherical or columnar shapes interposed between the alignment films 6A and 6B. The two transparent substrates 1 are formed by the spacer 9.
A and 1B are held at regular intervals.

The transparent segment electrode 3B on the upper surface of the transparent substrate 1B is connected to the transparent substrate 1 via a conductive member (not shown) contained in the sealing material 2 or the like.
A lead terminal 3C of each electrode 3A, 3B is formed at the right end of FIG. 1 on the lower surface of the transparent substrate 1A.

On the other hand, an electric circuit 13 is formed on the base film 12 of the flexible wiring board 11, and each of the electrodes 3A, 3B is connected to a terminal (not shown) formed at an end of the electric circuit 13. The lead terminal 3C is connected.
Further, an LSI 14 for controlling the liquid crystal display element 10 is connected to the electric circuit 13 of the flexible wiring board 11. In order to reduce the plane area of the liquid crystal display device, the flexible wiring substrate 11 has a curved portion 15 formed thereon and extends below the liquid crystal display element 10 as shown in FIG. In addition, it is electrically connected to a rigid power supply side wiring board 16 located below the liquid crystal display element 10.

In the backlight integrated type liquid crystal display device, a point light source 17 of a backlight such as a light emitting diode or a fluorescent lamp is provided at one end of the upper surface of the power supply side wiring board 16 facing the liquid crystal display element 10. Supported.

On the upper surface of the power supply side wiring board 16, a light guide plate 1 made of a substantially rectangular material such as acrylic is provided.
A light guide 20 having a guide frame 19 for supporting the light guide plate 18 and the light guide plate 18 is mounted. At the time of mounting, the point light source 17 is positioned beside the end face of the light guide 20. It has been done.

In the liquid crystal display device shown in FIG. 6, a plurality of prism sheets 21 are disposed on the upper surface of the light guide plate 18, and the light guide plate 18 and the guide frame 19 are provided.
Together, they constitute the light guide 20.

The light guide 20 and the liquid crystal display element 10 are bonded to an adhesive sheet 22 as an adhesive member formed in a substantially rectangular frame surrounding the display area of the liquid crystal display element 10 in the liquid crystal display device. Are adhered and fixed. Specifically, the light guide 20, more specifically, the guide frame 19 of the light guide 20 is attached to the back surface of the adhesive sheet 22, and the liquid crystal display element 1 having the above-described configuration is attached to the front surface thereof.
0, more specifically, the lower surface of the polarizing plate 7B is provided and fixed.

[0013]

Conventionally, when the point light source 17 is a point light source such as a fluorescent lamp, the point light source 17 is arranged in the display area of the liquid crystal display element 10 depending on the arrangement of the point light sources 17. There is a problem that illuminance unevenness occurs in which light and dark of band-like light are repeated in the direction in which are arranged, and good display cannot be obtained.

The light emitted from the point light source 17 functions as a backlight when passing through the inside of the light guide 20, and the light from the point light source 17 is, for example, the light guide. If the inner wall of the housing 24 of the liquid crystal display device facing the end face of the body is formed in white, light reflected on the inner wall is reflected in the direction of the liquid crystal display element 1 and is used again as a backlight. be able to. However, when the flexible wiring board 11 is provided between the end surface of the light guide 20 and the inner wall of the housing 24 of the liquid crystal display device 1, the flexible wiring board 11 is interposed. Only part can not reuse the reflected light. For this reason, the point light source 20
Light from the liquid crystal display element 10 could not function sufficiently as a backlight, and the display of the liquid crystal display element 10 might be partially difficult to see.

In the prior art, light leakage prevention tape has been conventionally attached to the end face of the light guide 20 to prevent light leakage. However, with such a configuration, the light leakage prevention tape can be used. The number of bonding steps increases, and the production efficiency of the liquid crystal display device deteriorates, and the cost of the liquid crystal display device may increase.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem. By preventing illuminance unevenness of a point light source, light from the point light source can function properly as a backlight. It is an object of the present invention to provide a liquid crystal display device capable of realizing good liquid crystal display by preventing light from leaking.

[0017]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a point light source of a backlight on a power supply side wiring board facing a liquid crystal display element; In a liquid crystal display device having a light guiding body mounted thereon and bonding the liquid crystal display element and the light guiding body via an adhesive sheet, at least one side edge of the adhesive sheet corresponds to the light guiding body. This is the point that the coating protruding edge which can cover the end face to be formed is provided.

[0018] By adopting such a configuration, the end face of the light guide plate can be covered.
It is possible to appropriately prevent light from leaking from the end face of the light guide plate to the outside of the device, and to prevent such light leakage with a simple configuration including the covering protrusion.

A feature of the liquid crystal display device according to a second aspect is that, in the first aspect, a diffuse reflection layer is provided on at least a portion of the back surface of the covering projection facing the end surface.

By adopting such a configuration, light leaked from the end face of the light guide plate is reflected to the liquid crystal display element side by the diffuse reflection layer having a large light reflectance, and is reused for liquid crystal display. Therefore, more light can be focused on the display area of the liquid crystal display element to realize a clearer and better liquid crystal display.

According to a third aspect of the present invention, there is provided a liquid crystal display device according to the first aspect, wherein one of the coating protruding edges is an end face of the light guide on which the point light source is disposed. The present invention covers a back portion of the point light source, and is characterized in that a diffuse reflection layer is provided on at least a portion of the back surface of the coating protruding edge located at the back portion of the point light source.

By adopting such a configuration, light leaked from the end face of the light guide plate is reflected to the liquid crystal display element side by the diffuse reflection layer having a large light reflectance, and is reused for liquid crystal display. Therefore, more light can be focused on the display area of the liquid crystal display element to realize a clear and good liquid crystal display, and the light emitted from the point light source is reflected toward the light guide by the diffuse reflection layer. Since more light can pass through the light guide, it is possible to make the illuminance unevenness appearing as light and dark of the band-like light generated in the direction in which the point light sources are arranged inconspicuous, further clear and good Liquid crystal display can be realized.

[0023]

FIG. 1 shows an embodiment of an adhesive sheet 22 of a liquid crystal display device according to the present invention and a mounting structure using the adhesive sheet 22. As shown in FIG. The same or corresponding components as those of the above-described conventional device will be described with the same reference numerals in the drawings.

The adhesive sheet 22 according to the present embodiment is configured such that the liquid crystal display element 10 and the light guide 20 are connected to the liquid crystal display element 1.
A substantially rectangular frame-shaped sheet 22A to be attached so as to surround the display area of No. 0, and protrudingly provided on one side edge of the frame-shaped sheet 22A to cover a corresponding end face of the light guide 20. And a flange-shaped covering protruding edge 22B.

The covering protruding edge 22B can be formed on all side edges of the frame-shaped sheet portion 22A, but at least the end face of the light guide 20 and the liquid crystal display device 1 as described above. The flexible wiring board 11 is disposed between the inner wall of the casing 24 and the casing 24 of the liquid crystal display device.
The light guide 20 is formed so as to correspond to the end face of the light guide 20 which is not expected to reflect and reuse the light reflected from the inner wall of the light guide 20.

In the embodiment shown in FIG. 1, the covering projection 22B covers the end face of the light guide 20 where the point light source 17 is provided and the back of the point light source 17. A white diffuse reflection layer 23 is formed on at least a portion of the back surface of the coating protruding edge 22B located behind the point light source 17.
Is provided.

That is, since white generally has a high light reflectivity, by making the diffuse reflection layer 23 white, light leaking from the end face of the light guide 20 is favorably reflected to the light guide 20 side. be able to. The diffuse reflection layer 23 is not limited to the white color described above, but may be, for example, a silver mat.

By adopting such a configuration, the light leaking from the end face of the light guide 20 is reflected to the liquid crystal display element 1 side by the diffuse reflection layer 23 having a large light reflectance, and the liquid crystal display is formed. Can be reused for
The light from the point light source 17 is transmitted by the diffuse reflection layer 23 to the light guide 2.
Since the light is reflected to the 0 side and more light can be collected in the light guide 20, unevenness in illuminance appearing as light and dark of the band-like light generated in the arrangement direction of the point light sources 17 can be made inconspicuous, and further clear. And a good liquid crystal display can be realized.

Further, in the present embodiment, the width dimension of the portion where the coating protruding edge 22B is formed is formed larger than the width dimension of the corresponding end face of the light guide 20. A weakening line 22C made of a perforation is formed at a connecting portion between the frame-shaped sheet portion 22A and the covering edge 22B, and the covering edge 22B is bent toward the corresponding end surface of the light guide 20. It is made easy.

The end face of the light guide 20 can be properly covered by the covering protruding edge 22B of the adhesive sheet 22 thus configured up to both ends in the longitudinal direction in the width direction. From the outside of the apparatus.

Furthermore, since it is only necessary to form the covering protruding edge 22B on the adhesive sheet 22, the number of manufacturing steps can be reduced as compared with the case where the end face of the light guide plate 18 is covered with a light leakage prevention tape.

Next, the operation of the present embodiment will be described.

In mounting the adhesive sheet 22 on the liquid crystal display device, as shown in FIGS. 1 and 2, four point light sources 17 are arranged on one edge of the liquid crystal display element 10 so as to face the liquid crystal display element 10. A light guide 20 having a substantially rectangular light guide plate 18 made of a material such as acrylic and a guide frame 19 supporting the light guide plate 18 is mounted on the upper surface of the power supply side wiring board 16. The point light source 17 is disposed on the side of the end face 20.

In the liquid crystal display device shown in FIG. 1, a plurality of prism sheets 21 are provided on the upper surface of the light guide plate 18 so that the light guide 20 and the light guide plate 18 and the guide frame 19 are arranged together. Make up.

On the upper surface of the light guide 20, a frame-shaped sheet portion 22A formed in a frame shape surrounding the display area of the liquid crystal display element 10 in the liquid crystal display device, and the frame-shaped sheet portion 22A is formed. An adhesive sheet member 22 is provided which protrudes from one side edge and has a coating protruding edge 22B on the back surface of which a white diffuse reflection layer is formed. The liquid crystal display element 10 is provided above the adhesive sheet 22. Arranged and secured. In the mounting, the coating sheet 22 has a coating protruding edge 22B that covers the end surface of the light guide 22 on the side where the point light source 17 is provided and the back of the point light source 17. The liquid crystal display device is bent at the weakened line 22C so as to be positioned inside the flexible printed circuit board 11 for connecting the liquid crystal terminal 10 and the power supply side printed circuit board 16, that is, on the light guide 20 side. It is mounted on the body 24.

In the liquid crystal display device thus configured, the point light source 17 is turned on, and a part of the light emitted from the point light source 17 is directly transmitted, and another part of the light is transmitted to the point light source 17. The light is reflected toward the light guide 20 by the diffuse reflection layer 23 of the adhesive sheet 22 disposed on the back, and is incident on the light guide 20 indirectly.

In this way, the light from the point light source 17 is reflected toward the light guide 20 by the diffuse reflection layer 23 of the adhesive sheet 22 provided on the back of the light source 17, so that the light is generated because of the point light source 17. Illumination unevenness where light and dark of a strip-shaped light are repeated can be reduced.

Light incident from the side on which the point light source 17 is disposed proceeds to the side opposite to the point light source 17 while repeating total reflection inside the light guide 20 (correctly, the light guide plate 18).

The light traveling inside the light guide 20 is diffused directly or through a diffusion plate (not shown) to the liquid crystal display element 10 located near the upper part of the light guide 20. Thus, the display area of the liquid crystal display element 10 is irradiated with plane light.

At this time, in order to prevent a part of the light traveling in the light guide 20 from leaking to the power supply side wiring board 16 side without being totally reflected, the anti-liquid crystal of the light guide 20 is prevented. A reflective layer (not shown) is provided on the display element 10 side.

As described above, according to the liquid crystal display device having the above-described structure, the light from the point light source 20 can function properly as a backlight, so that good liquid crystal display can be performed.

The number of the covering protruding edges 22B is not limited to one as described above. For example, FIGS. 3 and 4
As shown in the figure, the liquid crystal display element 10 and the liquid crystal terminal 1
Flexible wiring board 11 for connecting power supply side wiring board 16 to power supply side
When two flexible wiring boards 11 are provided,
The adhesive sheet 2 provided with the two covering protruding edges 22B so as to cover the end surface of the light guide 20 provided thereon.
2 is formed and mounted on the liquid crystal display device.

Further, the covering protruding edge 22B is provided in a case where the flexible wiring board 11 is not disposed between the end face of the light guide 20 and the inner wall of the housing 24 of the liquid crystal display device 1. Even if there is, it is optional to form it on the side edge of the frame-shaped sheet portion 22A.

As described above, the covering protruding edge 22 of the adhesive sheet is used.
B is formed, and the light guide 2 is
By covering the corresponding end surface of the light emitting device, the light that is about to leak out from the end surface can be shielded by the coating protruding edge 22B, so that the light can be prevented from leaking to the outside of the device.

As described above, according to the present embodiment, it is possible to prevent the light from leaking from the end face of the light guide plate 18 to the outside of the device by the covering projection 22B.
7 can function properly as a backlight, and good liquid crystal display can be performed.

The flexible wiring board 11A is provided with a coating protruding edge 22.
Since only B needs to be formed, light leakage of the backlight can be properly prevented while reducing the number of manufacturing steps.

Further, the coating protruding edge 2 of the adhesive sheet 22
By providing the diffuse reflection layer 23 on a portion of the back surface of the light guide 20 opposite to the end face of the light guide 20, light leaking from the end face of the light guide 20 can be reused for liquid crystal display. More light can be collected in the display area of the liquid crystal display element 10, whereby a clearer and better liquid crystal display can be performed.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary. For example, the frame-shaped portion of the adhesive sheet may be formed with a black surface to have a function as a black mask for covering a non-display area of the liquid crystal display element 10.

In the above embodiment, the light guide 20 is constituted by the so-called light guide plate 18, the guide frame 19 and the prism sheet 21, but the essential components of the light guide 20 are the light guide plate. 18, and it is also possible to adopt a configuration in which the engaging projection 25 is formed at the edge of the so-called light guide plate 18. When the prism sheets 21 are provided, the number of the prism sheets 21 is not limited to three in the present embodiment.
One sheet may be used.

[0050]

As described above, according to the first aspect of the present invention,
According to the liquid crystal display device according to the above, since light leakage of the backlight can be properly prevented by the covering protrusion having a simple configuration, a good liquid crystal display is realized while reducing the number of manufacturing steps of the liquid crystal display device. be able to.

Further, according to the liquid crystal display device of the second aspect, by forming the diffuse reflection layer having a large reflectance, light leaking from the end face of the light guide plate to the flexible wiring board can be favorably transmitted to the light guide plate. Since the light can be reflected, more light can be focused on the display area of the liquid crystal display element to realize a clearer and better liquid crystal display.

Further, according to the liquid crystal display device of the third aspect, by forming a diffuse reflection layer having a large light reflectance, the light leaking from the end face of the light guide plate is reflected toward the liquid crystal display element side, so that the liquid crystal display device can be used. Because of this, more light can be focused on the display area of the liquid crystal display element to realize a clear and good liquid crystal display, and the light emission of a point light source can be By reflecting the light toward the light guide side and allowing more light to pass through the light guide, it is possible to make the illuminance unevenness appearing as the brightness of the band-like light generated in the direction in which the point light sources are arranged inconspicuous. And a clear and excellent liquid crystal display can be realized.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a liquid crystal display device showing an adhesive sheet in the liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view illustrating an example of a mounting structure of an adhesive sheet in the liquid crystal display device of the present invention.

FIG. 3 is a plan view showing a positional relationship between an adhesive sheet having a coating protruding edge formed at a different position from FIG.

FIG. 4 is a plan view of the adhesive sheet of FIG. 3;

FIG. 5 is a longitudinal sectional view showing an example of a general liquid crystal display element.

FIG. 6 is a sectional view showing an example of a mounting structure of an adhesive sheet in a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquid crystal display element 11 Flexible wiring board 12 Base film 13 Electric circuit 14 LSI 15 Curved part 16 Power supply side wiring board 17 Point light source 18 Light guide plate 19 Guide frame 20 Light guide 21 Prism sheet 22 Adhesive sheet 22A Frame sheet part 22B Coating protruding edge 22C Weak line 23 Diffuse reflection layer 24 Housing

Claims (3)

[Claims] 1. A light guide for guiding light of a point light source of a backlight is mounted on a power supply side wiring board facing a liquid crystal display element, and the liquid crystal display element and the light guide are connected via an adhesive sheet. A liquid crystal display device comprising a bonded liquid crystal display device, characterized in that at least one side edge of the adhesive sheet is provided with a coating protruding edge that can cover a corresponding one end surface of the light guide. 2. The liquid crystal display device according to claim 1, wherein a diffuse reflection layer is provided on at least a portion of the back surface of the coating protruding edge facing the end surface. 3. One of the covering protruding edges covers an end surface of the light guide on which the point light source is disposed and a back portion of the point light source. 2. A diffuse reflection layer is provided on at least a portion of the back surface located behind the point light source.
3. The liquid crystal display device according to 1.