JP2002131725A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal device in which elongation and contraction of a light guide plate due to changes in the ambient temperature can be absorbed to prevent warpage of the light guide plate. SOLUTION: The liquid crystal display device 1 is equipped with a liquid crystal cell 2, a tablet 11 disposed above the liquid crystal cell 2, and a front light unit 6 disposed between the tablet 11 and the liquid crystal cell 2. The front light unit 6 consists of an illumination device 7 and a light guide plate 8 provided with the illumination device 7 in one end 8a side to allow the light from the illumination device 7 to enter the end face 8a and to exit to the liquid crystal cell 2 side. The front light unit 6 is held by a second case 9 as a case member, and an elastic holding part 10 which can elastically hold the front light unit 6 is formed in the case member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a front light between a liquid crystal display cell and a tablet.

[0002]

2. Description of the Related Art In the field of conventional liquid crystal display devices, not only are they used as display devices installed in offices and homes, but also applications to mobile devices such as electronic notebooks and personal digital assistants are remarkable. is there. In these mobile devices, for example, when switching various functions such as calendar display, schedule display, address book management, etc., the functions are switched by touching the tablet on the icon mark on which the desired function is displayed with a pen or the like. Things to do have been suggested.

[0003] Alternatively, there has been proposed a device in which a desired image can be input by handwriting by drawing an image of a character or the like with a pen or the like on a tablet. Such a conventionally proposed liquid crystal display device 31 will be described with reference to FIG. 4. A liquid crystal cell 32 is configured such that a liquid crystal (see FIG. 4) is placed between a pair of insulating substrates 33 and 34 made of two glass plates facing each other. (Not shown) is enclosed. The liquid crystal cell 32 is held in a liquid crystal case 35.

[0004] Above the liquid crystal cell 32 in the figure, there is provided a front light unit 37 housed in the lighting case 36 and whose movement is restricted by a side wall 36 a of the lighting case 36. The front light unit 37 has a light guide plate 38 made of a transparent resin, and an illumination device 39 having a light source such as an LED is attached to one end of the light guide plate 38. Such a front light unit 37
The light guide plate 38 and the illumination device 39 are held in contact with the inner surface of the side wall 36 a of the illumination case 36.

[0005] A tablet 4 held in a tablet case 40 is provided above the front light unit 37.
An image such as a character can be input by operating the surface of the tablet 41 with a pen (not shown) or the like. In addition, a metal case 42 is provided in which a liquid crystal case 35 holding a liquid crystal cell 32, an illumination case 36 holding a front light unit 37, and a tablet case 40 holding a tablet 41 can be stored in a stacked state. ing. This metal case 42
Is formed by bending a metal plate into a box shape, and an opening 42b for exposing an operation area (not shown) of the tablet 40 is formed in the upper plate 42a.

A liquid crystal case 35 holding a liquid crystal cell 32, an illumination case 36 holding a front light unit 37, and a tablet case 40 holding a tablet 41 are stacked and stored in a metal frame 42. The liquid crystal case 35 is fixed to the metal frame 42, and the conventionally proposed liquid crystal display device 31 is assembled.

In such a liquid crystal display device 31, when the ambient temperature increases, the temperature of the light guide plate 38 increases, and the arrows A,
Extends in the B direction. Due to this elongation, the vicinity of the center of the light guide plate 38 was warped to the upper tablet 41 side or the lower liquid crystal cell 32 side. However, even if the light guide plate 38 warps, the upper and lower gaps S of the light guide plate 38 are as large as about 0.8 mm, so that the light guide plate 38 may contact the lower liquid crystal cell 32 or the upper tablet 41. There was no performance problem.

[0008]

However, liquid crystal display devices used in mobile devices such as mobile phones have recently been required to be small and thin in order to improve portability.
2 and the light guide plate 38 and the size of the gap S between the light guide plate 38 and the tablet 41 were reduced. When the size of the gap S becomes small, when the light guide plate 38 warps due to a rise in temperature, the light guide plate 38 comes into contact with the lower liquid crystal cell 32 or the upper tablet 41, and this contact portion has a Newton ring or the like. There was a problem that interference fringes were generated, making it difficult to see a display image such as a character on the liquid crystal cell 32. An object of the present invention is to provide a liquid crystal device which solves the above-described problems and absorbs expansion and contraction of a light guide plate due to a change in ambient temperature, thereby preventing warpage of the light guide plate. is there.

[0009]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal cell; a tablet disposed above the liquid crystal cell;
A front light unit disposed between the tablet and the liquid crystal cell; the front light unit includes a lighting device, and the lighting device is disposed on one end side and the light of the lighting device is transmitted to the one end portion. A light guide plate for allowing light to enter from the side and exiting to the liquid crystal cell side, wherein the front light unit is held by a case member, and an elastic holding portion capable of elastically holding the front light unit is formed on the case member. did.

As a second means for solving the above problem, the case member has a side wall surrounding an outer peripheral portion of the front light unit, and the elastic holding portion is provided on an outer side of the lighting device. And / or on the inner surface of the side wall on the side where the other end of the light guide plate facing the one end is located.

According to a third aspect of the present invention, the elastic holding portion includes an elastic contact portion capable of elastic contact with the outer portion of the lighting device and / or the other end of the light guide plate. And a support portion for supporting the elastic contact portion on the side wall in a state in which the elastic contact portion is separated inward from the side wall. When a biasing force is applied to the elastic contact portion, the support portion is elastically deformed. The elastic contact portion is configured to move.

As a fourth solution for solving the above-mentioned problem, the support portion is formed in a wave-like curved shape.
The support portion supports the elastic contact portion on the side wall at both ends.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device of the present invention will be described with reference to the drawings. First, FIG. 1 is an exploded perspective view of a liquid crystal display device of the present invention, FIG. 2 is a sectional view of a main part of FIG. 1, and FIG. 3 is a plan view of a second case which is a case member according to the present invention. .

The liquid crystal device 1 of the present invention will be described with reference to FIGS. 1 to 3. First, as shown in FIG.
A pair of insulating substrates 2 and 3 made of two rectangular glass plates are disposed so as to face each other.
A liquid crystal (not shown) is sealed between them.
Further, a polarizing plate (not shown) is attached to the upper surfaces of the pair of insulating substrates 3 and 4 in which liquid crystal is sealed. Also,
A reflecting member (not shown) is attached to the lower surface of the liquid crystal cell 2 shown in the drawing, so that light from the outside incident on the liquid crystal cell 2 is reflected upward by the reflecting member and emitted to the outside. Has become. As shown in FIG. 1, such a liquid crystal cell 2 includes a driver IC 2 mounted on an end of a lower substrate 4 to drive each electrode (not shown) of the liquid crystal cell 2.
The flexible printed circuit board 2b connected to the terminal a and the like is provided.

The first case 5, which can hold the liquid crystal cell 2 and regulate the movement of the liquid crystal cell 2, is made of a resin material.
A side wall 5a surrounding the outer periphery of the liquid crystal cell 2;
And a bottom plate 5b that covers the entire rear surface of the base plate 5b. Also,
A hook-shaped hook portion 5 which can be snap-engaged with an engagement portion 13d of the metal frame 13 described later is provided on an outer peripheral portion of the side wall 5a.
c is protrudingly formed.

A front light unit 6 is arranged above the liquid crystal cell 2 in the figure. The front light unit 6 includes a light source (not shown) including an LED or the like.
And a light guide plate 8 to which the lighting device 7 is attached on one end 8a side. The light guide plate 8
Is a flat plate of a predetermined thickness made of a transparent resin, the outer shape is formed in a rectangular shape, and the other end 8b is formed on the side facing the one end 8a to which the lighting device 7 is attached. In addition, the light guide plate 8 allows light from the light source of the lighting device 7 to enter from one end 8a side and emit to the lower liquid crystal cell 2 side. The light guide plate 8 has a characteristic that it expands and contracts due to a change in the surrounding environmental temperature. As a result, it was increased by about 0.5%.

Further, the front light unit 6 is held by a second case 9 which is a case member, and an elastic holding portion 10 capable of elastically holding the front light unit 6 is formed on the second case 9. The second case member
The case 9 is made of a resin material, has a side wall 9 a surrounding the outer periphery of the front light unit 6, and forms an elastic holding portion 10 on the inner surface of the side wall 9 a on which the lighting device 7 is located. The second case 9 includes the lighting device 7 and the light guide plate 8.
A cross-shaped bottom plate 9b is formed to cover the rear surface near the outer peripheral portion. The thickness of the bottom plate 9b is, for example, 0.2 mm.
It is formed thin.

As shown in FIG. 3, the elastic holding portion 10 has an elastic contact portion 10a capable of elastic contact with the outer portion 7a of the lighting device 7.
And a supporting portion 10b for supporting the elastic contact portion 10a on the side wall 9a in a state in which the elastic contact portion 10a is separated inward from the side wall 9a. 1
0b is elastically deformed, so that the elastic contact portion 10a moves toward the side wall 9a.

As shown in FIG. 3, the supporting portion 10b is formed in a wave-like curved shape.
b supports the elastic contact portion 10a on the side wall 9a at both ends. Therefore, even if the light guide plate 8 incorporated in the second case 9 expands and contracts due to heat, the elastic contact portion 10a moves following the expansion and contraction to absorb the expansion and contraction of the light guide plate 8. Can be. Therefore, the warpage of the light guide plate 8 as described in the conventional example can be prevented. Further, the bottom plate 9b of the second case 9 is formed to be thin with a thickness of 0.2 mm.

On the upper part of the front light unit 6, there is provided a transparent panel, that is, a tablet 11 capable of inputting images such as characters by performing a switching operation by operating a pen (not shown) or the like. This tablet 1
1 is formed in a rectangular shape having substantially the same shape as the liquid crystal cell 2 as shown in FIG. 1, and a plurality of electrodes (not shown) are formed near the outer peripheral end. The upper part of this electrode is covered with a resin material such as a resist or the like, is insulated, and is connected to the flexible printed circuit board 11a. Further, an operation area (not shown) in which an image such as a character can be input by operating a pen or the like positioned on the tablet 11 is formed in a region surrounded by the electrodes at the outer peripheral end.

The third case 12, which can hold the tablet 11 and restrict its movement, is made of a resin material and covers the side wall 12a surrounding the outer periphery of the tablet 11 and the back surface near the outer periphery of the tablet 11. A bar-shaped bottom plate 12b is formed. The bottom plate 12b is formed to be thin with a thickness of approximately 0.2 mm.

A metal frame capable of storing the first case 5 holding the liquid crystal cell 2, the second case 9 holding the front light unit 6, and the third case 12 holding the tablet 6 in a stacked state. 13 are provided. The metal frame 13 is made of a stainless steel plate or the like. As shown in FIG. 1, the lower portion is released by bending or the like, the periphery is covered with a side plate 13a, and the upper plate 1
3b is formed in a box shape. An opening 13c that exposes an operation area (not shown) of the tablet 11 operable with a pen or the like is formed through the upper plate 13b. The side plate 13a has a slit-shaped engaging portion 13d.
Are formed by punching, and the hook portion 5 of the first case 5 housed inside the metal frame 13 is formed in the engagement portion 13d.
c can be snap-engaged.

The assembling of the liquid crystal display device 1 according to the first embodiment having such a configuration will be described. First, the liquid crystal cell 2 is assembled into the first case 5. Next, the front light unit 6 in which the lighting device 7 is attached to the light guide plate 8 is incorporated in the second case 9 which is a case member. Then, in the front light unit 6, the other end portion 8 b of the light guide plate 8 abuts against the side wall 9 a of the second case 9, and the outer portion 7 a of the lighting device 7 elastically contacts the elastic holding portion 10 to elastically contact the second case 9. Will be retained. Then, the second case 9 incorporating the front light unit 6 is positioned and laminated on the first case 5 incorporating the liquid crystal cell 2.

Next, the tablet 11 is assembled in the third case 12, and the third case 12 is positioned and laminated on the second case 9 in which the front light unit 6 is incorporated. Next, when the metal frame 13 is placed over the first case 5, the second case 9, and the third case 12 in a stacked state, and the upper plate 13b of the metal frame 13 is pressed downward, the engaging portion formed on the side plate 13a is formed. 13d is snap-engaged with the hook portion 5c of the first case 5, and the assembly of the liquid crystal display device 1 is completed.

In the liquid crystal display device 1 of the present invention assembled as described above, since the front light unit 6 is elastically held by the elastic holding portion 10 formed in the second case 9, the surrounding environmental temperature rises. Even if the light guide plate 8 extends in the direction of arrow C, the light guide plate 8 does not warp as described in the conventional example. For this purpose, the thickness of the bottom plates 9b and 12b of the second and third cases 9 and 12 is reduced, and the lower liquid crystal cell 2 of the front light unit 6 and the upper tablet 1 are formed.
1 can be reduced to about 0.2 mm.

In the embodiment of the present invention, the elastic holding portion 10 has been described as being formed on the inner surface of the second side wall 9a on the side where the outer portion 7a of the lighting device 7 is located. The second side wall 9 on the side where the other end 8b of the light guide plate 8 is located
It may be formed on the inner surface of a. Alternatively, the elastic holding portion 10 may be formed on the inner surface of both the second side wall 9a where the outer portion 7a of the lighting device 7 and the other end portion 8b of the light guide plate 8 are located. That is, in the liquid crystal display device 1 of the present invention, the elastic holding portion 10 is formed by the inner surface of the side wall 9a on the side where the outer portion 7a of the lighting device 7 is located and / or the side wall 9a on the side where the other end portion 8b of the light guide plate 8 is located. What is necessary is just to be what was formed in the inner surface.

[0027]

According to the liquid crystal display device of the present invention, the front light unit is held by the case member, and the case member is formed with the elastic holding portion capable of elastically holding the front light unit. The light guide plate can be prevented from warping by absorbing a dimensional change of the light guide plate due to a change in ambient temperature. Therefore, the gap between the liquid crystal cell below the light guide plate and the tablet above can be reduced, and a liquid crystal display device that can be made thinner can be provided.

Further, the elastic holding portion may be provided on the inner surface of the side wall on the side where the outer portion of the lighting device is located and / or on the side wall on the side where the other end opposite to the one end of the light guide plate is located. Since it is formed on the inner surface, it is possible to provide a high-performance liquid crystal display device capable of securely holding the front light unit elastically to the case member and absorbing expansion and contraction of the light guide plate.

Further, when a biasing force is applied to the elastic contact portion, the support portion is elastically deformed and the elastic contact portion is moved, so that the front light unit is reliably elastically attached to the case member by the elastic contact portion. Can be held.

Further, since the support portion is formed in a wave shape and the elastic contact portion is supported on the side wall by the support portion, the elastic contact portion can be moved smoothly, and the light guide plate can expand and contract. Even so, the expansion and contraction can be reliably absorbed.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a main part of FIG.

FIG. 3 is a plan view of a case member according to the present invention.

FIG. 4 is a sectional view of a main part of a conventional liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal display device 2 liquid crystal cell 3 insulating substrate 4 insulating substrate 5 first case 5c hook portion 6 front light unit 7 lighting device 7a outer portion 8 light guide plate 9 second case 9a second side wall 10 elastic holding portion 10a elastic contact portion 10b Support part 11 Tablet 12 Third case 13 Metal frame 13d Engagement part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00366 G02F 1/1335 530 F-term (Reference) 2H089 HA40 QA06 QA16 TA17 TA18 TA20 2H091 FA23X FA41X FA45X FD06 LA04 LA21 5B087 AB04 AE09 CC02 CC12 CC13 5G435 AA01 AA12 BB12 BB15 EE06 EE23 EE27 FF08

Claims (4)

[Claims] A liquid crystal cell; a tablet disposed above the liquid crystal cell; and a front light unit disposed between the tablet and the liquid crystal cell. A light guide plate disposed on one end side of the lighting device, the light from the lighting device is made incident from the one end side and emitted to the liquid crystal cell side, and the front light unit is held by a case member; A liquid crystal display device wherein an elastic holding portion capable of elastically holding the front light unit is formed in the case member. 2. The case member has a side wall surrounding an outer peripheral part of the front light unit, and the elastic holding part is provided on an inner surface of the side wall on a side where an outer part of the lighting device is located and / or the conductive member. The liquid crystal display device according to claim 1, wherein the light plate is formed on an inner surface of the side wall on a side where the other end portion facing the one end portion is located. 3. The elastic holding portion includes a resilient contact portion capable of resiliently contacting the outer portion of the lighting device and / or the other end portion of the light guide plate, and the resilient contact portion moving inward from the side wall. A support portion that supports the side wall in a separated state, and when an urging force is applied to the elastic contact portion, the support portion elastically deforms and the elastic contact portion moves. Claim 2
The liquid crystal display device according to the above. 4. The support portion is formed into a wave shape,
4. The liquid crystal display device according to claim 3, wherein the elastic contact portion is supported at both sides of the side wall by the support portion.