JP2003228066A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display equipped with a light guide plate having a high-strength projection part. <P>SOLUTION: The liquid crystal display which has a projection part 32 projecting from the light guide plate 1 and fitted in a groove part 33 formed on a back light chassis 5, is characterized in that border parts 37 and 38 between the projection part 32 of the light guide plate 1 and the light guide plate 1 are formed not in a right-angled shape, but in a curved-surface shape. Consequently, for example, even if some shock is applied to the light guide plate 1, the shock (force) is received with the wide area (curved surface) of the border parts 37 and 38 and can be dispersed over the curved surface without being concentrated on a narrow range (side part). Consequently, the projection part 32 (light guide plate 1) can be prevented from breaking (cracking) and the strength of the light guide plate 1 can be improved. <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 having a light guide plate.

[0002]

2. Description of the Related Art A liquid crystal display device displays an image using a liquid crystal display panel having pixels. by the way,
Usually, this liquid crystal display panel is not a light emitting body, and thus external light from the liquid crystal display panel is required to display an image. Therefore, the liquid crystal display device includes a backlight device for irradiating the liquid crystal display panel with light.

Now, the backlight device will be described. The backlight device is a fluorescent tube device that emits light,
From a backlight exterior part that includes a reflection sheet that reflects light, a light guide plate that guides the reflected light to a diffusion sheet, and a diffusion sheet that diffuses the light guided to the light guide plate and irradiates the liquid crystal display panel uniformly. It is configured. Further, the backlight exterior part also has a function of fixing the liquid crystal display panel.

By the way, in recent years, liquid crystal display devices have been made thinner and lighter, and the liquid crystal display panel has been increased in size, so that the liquid crystal display panel can be used as a backlight exterior part while maintaining a large display area. Required to be attached. Therefore, it is necessary to reduce the peripheral portion (frame) of the liquid crystal display panel (narrow the frame of the liquid crystal display panel).

Thus, when the frame is reduced, the display area of the liquid crystal display panel becomes wider. Therefore, the light guide plate is
Since the light must be guided over the entire display area, it is necessary to increase the area.

In order to fix such a large-sized light guide plate to the backlight chassis (frame body) of the backlight exterior portion, it is necessary to increase the mounting strength between the light guide plate and the backlight chassis. .

A liquid crystal display device adapted to such a frame reduction is proposed in, for example, Japanese Unexamined Patent Publication No. 9-152577.

In this liquid crystal display device, as shown in FIG. 8, a recess (groove) is formed in the inner frame of the backlight chassis 105.
While providing 133, the convex portion (projecting portion) 132 is provided on the side surface of the light guide plate 101. Then, by fitting and fitting the concave portion 133 and the convex portion 132, the light guide plate 1
01 is prevented from slipping off or shifting from the backlight chassis 105, and the mounting strength is improved.

[0009]

However, in the liquid crystal display device of the above-mentioned publication, as shown in FIG. 9, a convex portion 132 for fixing the light guide plate 101 to the backlight chassis 105 (see FIG. 8) and a conductive portion are provided. The shapes of the boundary portions 137 and 138 with the side surface of the optical plate 101 are right angles (orthogonal).

Therefore, when some sort of impact is applied to the backlight device of the liquid crystal display device, the light guide plate 101 tries to move in the direction of the arrow F, and the boundary portions 137 and 138.
Force (load) to contact the groove 133 (see FIG. 8)
Takes. However, since the boundary portions 137 and 138 are angular, the area to which the force is applied is small (the force is concentrated on one side of the boundary). Therefore, the force cannot be dispersed. Therefore, these points (boundary 137.
138) may crack.

The present invention has been made to solve the above conventional problems. And the objective is to provide the liquid crystal display device provided with the light guide plate which has a high strength protrusion part.

[0012]

In order to solve the above-mentioned problems, a liquid crystal display device of the present invention (present liquid crystal display device) is a projection portion protruding from a side surface of a light guide plate for guiding backlight light to a liquid crystal display panel. A liquid crystal display device fitted into a groove provided on an inner wall of a frame for fixing the light guide plate provided in the liquid crystal display device, wherein a boundary portion between the protrusion and the side surface of the light guide plate has a curved shape. It is characterized by becoming.

In the present liquid crystal display device, a light guide plate is fitted and fixed in a frame provided in the liquid crystal display device itself. For this fixing, a protrusion is provided on the side surface of the light guide plate and a groove is provided on the inner wall of the frame.

Further, in the present liquid crystal display device, the boundary between the above-mentioned protrusion and the light guide plate is curved. This curved surface shape is a curved surface that dents inward (for example, near the center of the light guide plate) from the boundary portion, and has a so-called R-processed shape (R shape).

With such a curved surface shape, for example, even when an impact (force) is applied to the light guide plate, the impact applied to the protrusion is received over a wide area (curved surface). Therefore, the impact is dispersed without concentrating in a narrow range (boundary), and the light guide plate (boundary) is not cracked.
Therefore, in the present liquid crystal display device, the impact resistance of the light guide plate can be improved. In addition, the above-mentioned protrusion is
It can be said that the member has a shape that absorbs a load.

Further, in the liquid crystal display device of the present invention, in addition to the above structure, it is preferable that the surface of the protrusion is roughened to diffuse and reflect the backlight light. Alternatively,
It is preferable that a tape for diffusing and reflecting the backlight is attached to the surface of the protrusion.

The roughened surface or tape described above diffuses and reflects the light incident on the light guide plate. As a result, it is possible to prevent the specular reflection of light at the protrusions (specular reflection causes a part where light does not reach the liquid crystal display panel,
It also causes uneven brightness (uneven light amount) due to light with a strong directivity).

That is, in the present liquid crystal display device, since the light incident on the protrusion is diffusely reflected by the tape or the roughened surface, the light can reach the entire area of the liquid crystal display panel. Therefore, it is possible to suppress the uneven brightness of the liquid crystal display panel caused by the portion where the light does not reach, and it is possible to improve the display quality.

In the liquid crystal display device of the present invention, in addition to the above structure, it is preferable that the above-mentioned tape has a single sheet shape that covers the side surface of the protrusion and the incident surface of the backlight.

For example, if a tape consisting of two sheets is used,
One piece is attached to the side surface of the protrusion and the other piece is attached to the surface on the side where the light is incident, so that a gap may occur between the tapes.

However, by using the one-piece tape, it is possible to completely cover the light incident site on the protrusion without generating a gap. Therefore, the light incident on the protrusion can be efficiently diffused and reflected, so that the uneven brightness of the liquid crystal display panel can be further suppressed, and the display quality of the liquid crystal display panel can be further improved.

Further, the workability can be improved by using a single-shaped tape, as compared with the case of using two tapes.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described.

FIG. 2 is an explanatory view showing the structure of the liquid crystal display device (present liquid crystal display device) 21 according to this embodiment. In addition, in this explanatory view, directional axes in the XYZ directions are shown in order to clarify the three-dimensional positional relationship.

As shown in this figure, the present liquid crystal display device 21
Is composed of a backlight device 13, a liquid crystal display panel 14 having a substrate 16 and the like, and a frame 15.

The liquid crystal display panel 14 is a display panel having a plurality of pixels.

The frame 15 is a metal frame and is a member for attaching the liquid crystal display panel 14 to the backlight device 13.

The backlight device 13 irradiates the liquid crystal display panel 14 with light (backlight light), and is composed of a fluorescent tube device 11 and a backlight exterior portion 12.

The fluorescent tube device 11 emits light and comprises a fluorescent tube 2, a lamp reflector 3 and a lamp cover 4.

The fluorescent tube 2 is a light source. The lamp reflector 3 reflects the light from the fluorescent tube 2 toward the backlight exterior portion 12. The lamp reflector 3 is attached so as to surround the fluorescent tube 2.

The lamp cover 4 protects the fluorescent tube 2 and the lamp reflector 3. The lamp cover 4 is attached so as to cover the fluorescent tube 2 and the lamp reflector 3.

The fluorescent tube device 11 is attached to a predetermined position P of the backlight chassis 5 (described later).

The backlight exterior part 12 is composed of a backlight chassis 5 (frame), a reflection sheet 6, a light guide plate 1, a diffusion sheet 7, a lens sheet 8 and a diffusion sheet 9 with light-shielding printing, in this order. It is attached so that it overlaps.

The backlight chassis 5 is the fluorescent tube device 1
1 for holding the reflection sheet 6, the light guide plate 1, the diffusion sheet 7, the lens sheet 8, and the diffusion sheet 9 with light-shielding print, and the liquid crystal display device 1 (backlight exterior portion 12).
It is a resin-made frame-shaped member that serves as a base (base). In addition, as shown in FIG. 1, a protrusion 32 of the light guide plate 1 described later.
A groove portion 33 for fitting is provided on the inner wall of the frame.

The reflection sheet 6 reflects the light from the fluorescent tube device 11 to the light guide plate 1.

The light guide plate 1 shown in FIG. 3 is a member for guiding the reflected light from the reflection sheet 6 to the diffusion sheet 7. As shown in FIG. 4, the rear surface of the light guide plate 1 (the surface on the side of the reflection sheet 6; see FIG. 2) is for irradiating the liquid crystal display panel 14 with the light incident from the fluorescent tube device 11 described above. (Fig. 2
And a diffusion processing pattern (dot pattern 31). The size and density of this dot pattern may be adjusted so that the above-mentioned light (incident light) reaches the liquid crystal display panel 14 more.

As shown in FIGS. 3 and 4, a mounting portion (projection portion) 32 for mounting the light guide plate 1 on the backlight chassis 5 (see FIG. 2) is provided on the side surface of the light guide plate 1. (Protruding). The size of the light guide plate 1 is 288.7 mm in length and 217.7 mm in width.

The diffusion sheet 7 is a member used to diffuse the light from the reflection sheet 6 and uniformly irradiate the liquid crystal display panel 14 with light.

The lens sheet 8 is a member that polarizes the radiation characteristic of light incident on the liquid crystal display panel 14 in order to improve the brightness per unit area of the liquid crystal display panel 14. In the liquid crystal display device 21, two lens sheets 8 are stacked in order to further improve the brightness.

The light-shielding printed diffusion sheet 9 protects the lens sheet 8 and the surface of the liquid crystal display panel 14 (in the panel surface).
Can be made uniform, and light leakage from the end of the light guide plate 1 can be prevented (shielded).

The liquid crystal display device 21 is constructed by disposing the liquid crystal display panel 14 on which the substrate 16 is mounted and the frame 15 on the above-mentioned backlight device 13 in this order at predetermined positions. Has been done. The substrate 16 is a PWB (Printed Wiring Board) on which components for driving the liquid crystal display panel 14 are mounted.

Next, the characteristic structure of the present liquid crystal display device 21 will be described.

In the present liquid crystal display device 21, as shown in FIG. 1, the side portions 35 and 36 of the protrusion 32 of the light guide plate 1 and the boundary portions 37 and 38 of the protrusion 32 and the light guide plate 1 are formed at right angles. Instead of a shape (rather than being angular), a curved surface shape, that is, a curved surface (R shape) having a radius of curvature (R) is formed (R processed). In addition, in the case of the boundary portions 37 and 38, this R shape is a curved surface that is dented toward the inside (for example, near the center of the light guide plate), and in the case of the side portions 35 and 36, toward the outside. It has a curved surface that is bulging.

Specifically, the side portion 35 / boundary portion 37 is radiused to a radius of 1.0 mm, and the side edge portion 36 / boundary portion 38 is radiused to a radius of 0.5 mm. There is.

The angle (taper angle) θ of the boundary portion 37 in FIG. 1 is preferably about 45 °, but is not limited to this angle.

As described above, the protrusion 3 of the light guide plate 1
When the side portions 35 and 36 and the boundary portions 37 and 38 of 2 are curved, for example, when the light guide plate 1 moves and the protrusion 32 and the groove 33 come into contact with each other, the protrusion 32
A large area (curved surface) receives an impact (force) applied to the side portions 35 and 36 and the boundary portions 37 and 38. Therefore, the impact can be dispersed on the curved surface without being concentrated on a narrow range (side portion). Therefore, breakage (cracking) of the protrusion 32 (light guide plate 1) can be prevented. As described above, the light guide plate 1 of the present liquid crystal display device 21 has high impact resistance.

The size of the radius of curvature (R) in the R processing is not particularly limited, but is 0.5 to 2.0 m.
About m is preferable.

Further, in order to confirm the effect of the above-mentioned R processing, an impact test was conducted by comparing the light guide plate 1 of the present liquid crystal display device 21 and the light guide plate 101 (see FIG. 8) of the conventional liquid crystal display device. . In this impact test, the liquid crystal display device is subjected to an impact of up to 70 G in the minus Y direction shown in FIG. 2 for 11 ms.

As a result of this experiment, in the light guide plate 101 of the conventional liquid crystal display device, the protrusion 132 was cracked and damaged at 50 G. However, in the light guide plate 1 of the present liquid crystal display device 21,
Even 0G did not crack. Therefore, it has been proved that the R processing for the light guide plate 1 of the present invention is effective against the impact.

Further, in the present liquid crystal display device 21, the groove portion 33 of the backlight chassis 5 may have a hole shape. That is, the groove 33 may be a hole formed in the inner wall of the backlight chassis 5. In this case, the protrusion 3 of the light guide plate 1
2 is attached so as to be embedded in the above hole. Moreover, you may make it join the protrusion part 32 and the groove part 33 mutually with an adhesive agent.

Further, in the present liquid crystal display device 21, as shown in FIG. 5, the side surface of the protrusion 32 of the light guide plate 1 and the surface on which the dot pattern 31 is formed (the surface of the fluorescent tube 2 on which the light enters); It is preferable to attach tapes (white tapes) 41 and 42 having a characteristic of diffusing and reflecting light (light diffusive reflection characteristic) to the reference (reference). Also, the tape 4 used in the present invention
1.42 is a Lintec WH50.

As shown in FIG. 6, each of the tapes 41 and 42 is composed of a transparent double-sided tape 51, a PET (polyethylene terephthalate) 52, and a white reflective layer 53. Specifically, the layers of PET 52 are sandwiched, and the transparent double-sided tape 5 is provided on one surface.
The white reflective layer 53 is located on the other surface.

A tape 41 having this light diffuse reflection characteristic
The reference numeral 42 diffuses and reflects the light reflected by the protrusions 32, and allows the light to reach a portion of the liquid crystal display panel 14 where the light hardly reaches.

With such tapes 41 and 42, it is possible to suppress the uneven brightness on the surface of the liquid crystal display panel 14 and improve the display quality.

In order to confirm the effect of the tapes 41 and 42, the light guide plate 1 to which the tapes 41 and 42 are attached is attached.
As a result of comparing the luminance unevenness between the light guide plate 1 on which the tapes 41 and 42 are not attached, the light from the fluorescent tube 2 is projected onto the protrusion 3 in the light guide plate 1 on which the tapes 41 and 42 are not attached.
Specular reflection at No. 2 caused a spot on the liquid crystal display panel 14 that looked like one stripe and a spot where light did not reach (dark spot). Therefore, the difference in light amount (unevenness of light amount) between the two places causes a large difference in contrast on the surface of the liquid crystal display panel 14, that is, uneven brightness.

On the other hand, in the light guide plate 1 to which the tapes 41 and 42 are attached, as described above, the light diffusely reflects and the light can reach the entire area of the liquid crystal display panel 14. As a result, uneven brightness did not occur.

In addition, in recent years, the thickness, weight, and frame of each part (module) of the liquid crystal display device have been reduced, the number of fluorescent tubes has been reduced from two to one, and the length of the fluorescent tube has become a light guide plate. On the other hand, it may not be possible to get enough. However, in the present liquid crystal display device 21, it is possible to suppress the corner black on the surface of the liquid crystal display panel 14 where the corners are black, and the uneven brightness around the protrusion 32 that fixes the light guide plate 1 to the backlight chassis 5.

The shapes of the tapes 41 and 42 are not particularly limited, but one tape as shown in FIG. 7 may be attached to the side surface of the protrusion 32 and the surface on which the dot pattern 31 is formed. A tape 43 having a different shape (single sheet shape) is preferable.

For example, when two tapes 41 and 42 are used, one tape is attached to the side surface of the protrusion 32 and another tape is attached to the surface on which the dot pattern 31 is formed.
A gap occurs between 1.42.

However, by using the one-piece tape 43, it is possible to completely cover the light incident portion of the protrusion 32 without generating a gap. Therefore, the protrusion 32
Since the light incident on the light can be diffusely reflected without passing through, it is possible to further suppress the uneven brightness of the liquid crystal display panel 14 and further improve the display quality thereof.

Further, the workability can be improved by using the tape 43 of one sheet shape, as compared with the case of using the tapes 41, 42 consisting of two sheets.

If the side surface of the protrusion 32 of the light guide plate 1 and the surface on which the dot pattern 31 is formed are roughened (roughened), the light from the fluorescent tube device 11 can be diffused and reflected.

Here, the light diffusion tape (tapes 41 to 43 to be attached to the side surface and the bottom surface (bottom portion; surface on which the dot pattern 31 is formed; light incident surface) of the protruding portion (ear portion) 32 of the light guide plate 1 ( Diffuse reflection tape; W made by Lintec
H50) will be described in more detail.

First, the attachment form of the light diffusion tape will be described. As described above, it is preferable that the light diffusion tape for suppressing the uneven brightness is “attached integrally (one piece) to the side surface and the bottom surface of the protrusion 32 of the light guide plate 1” (that is, the tape 43 is attached). It is preferable to use).

In this way, the protrusion 3 formed by the bottom surface and the side surface is formed.
By covering the second edge (edge of the ear) with one piece of tape 43, it is possible to further suppress the uneven brightness, as compared with attaching one piece to the bottom surface and one piece to the side surface, and the liquid crystal display panel 14
The display quality of can be further improved. Further, by covering with one tape 43, it is possible to improve workability during manufacturing, as compared with using two tapes 41 and 42. In addition,
Regarding the merit of using one tape 43,
It is also described in "Mechanism for suppressing luminance unevenness" described later.

It is very important that the light diffusing tape used in the present liquid crystal display device 21 is a tape. That is, as described above, the liquid crystal display device 21 is (or can be) used in the liquid crystal display device 21.
As the diffusion member, a diffusion processing pattern (dot pattern 31) obtained by printing, the diffusion sheet 7, and
The roughened surface of the light guide plate 1 can be raised.

However, attaching the light diffusing tape is a very easy operation as compared with the case of installing other diffusing members. That is, the light diffusing tape is superior to other diffusing members in that the light diffusing tape has a small turning angle and can flexibly respond. For example, when uneven brightness occurs in the light guide plate 1 that has already been molded, the uneven brightness can be easily improved by attaching (installing) a tape having a shape corresponding to the uneven brightness on the part that causes the uneven brightness. Can be (suppressed).

Further, the surface is simply roughened (roughened).
When the light is diffused, other portions that come into contact with the roughened portion may be damaged. On the other hand, if the light diffusing tape has a flat surface, such a problem can be avoided.

Further, the light diffusing tape can be said to have the same properties as other diffusing members in terms of expression (in terms of words) in terms of "diffusing light". However, the light diffusing tape is different from other diffusing members in the mechanism of diffusing light. In this regard,
This will be described in "Mechanism for suppressing luminance unevenness" described later.

Next, the "mechanism for suppressing luminance unevenness" in the light diffusing tape will be described. As mentioned above,
It can be said that the light diffusing tape has the same property as the roughened surface of the light guide plate 1 in terms of “diffusing light”. However, the mechanism of light diffusion by the light diffusion tape is different from roughening.

The difference between the case where the surface of the light guide plate 1 (projection 32) is roughened and the case where the light diffusion tape is attached will be described below. 10B and 10C are the same as FIG.
For the portion A of the protrusion 32 of the light guide plate 1 shown in (a),
It is explanatory drawing which shows the cross section of the part A at the time of (b) roughening a surface and the case where a light-diffusion tape is stuck to the (c) surface.

Further, FIG. 11 shows a roughened protrusion 32.
It is explanatory drawing which expands and shows the surface (cross section) of. As shown in this figure, when light is incident on the rough surface, irregular reflection is repeated on the rough surface, so that the emission direction of the light is diffused.

Further, as shown in FIG. 11, when the surface (rough surface) of the roughened projection 32 in the light guide plate 1 (made of acrylic) is viewed microscopically, the light reaching the rough surface is as described above. Is reflected by the rough surface () or penetrates the light guide plate 1 through the rough surface ().

Whether it is reflected or transmitted is determined by the Fresnel's formula from the incident angle of light and the refractive index (acrylic and air layers) on the rough surface. That is, in the diffusion of light by roughening, depending on the incident angle with respect to the rough surface and the shape of the rough surface, the incident light passes through the acrylic light guide plate 1 and escapes to the air layer, resulting in a loss. There is.

On the other hand, when light is diffused by the light diffusing tape, a transparent double-sided tape (adhesive layer) is formed on the surface of the light guide plate 1.
51 and the diffuse reflection base material including the PET 52 and the white reflection layer 53 are stacked in close contact with each other. Therefore, there is no air layer between the light guide plate 1 and the light diffusion tape.

When light is incident from one having a large refractive index to one having a small refractive index, if the incident angle is the same, the latter having a larger refractive index is more likely to enter (incident) into the latter. Then, the refractive index of each layer is as follows: light guide plate 1; 1.49, air layer; 1, adhesive layer (transparent double-sided tape 51);
Diffuse reflection base material; larger than the adhesive layer.

Therefore, as shown in FIGS. 12A and 12B, the light guide plate 1 (acrylic) and the transparent double-sided tape (adhesive layer).
The proportion of light incident on the transparent double-sided tape 51 at the interface with 51 is larger than that at the interface between the light guide plate 1 and the air layer (when light is incident at the same angle, the former allows more light to pass through. Be).

Further, FIG. 12C is an enlarged view of the interface portion B (a part of the interface between the diffuse reflection substrate composed of the PET 52 and the white reflective layer 53 and the transparent double-sided tape 51) shown in FIG. 12B. It is a figure. As shown in this figure, the interface between the diffuse reflection base material and the transparent double-sided tape 51 is uneven. Therefore, incident light can be satisfactorily diffused and reflected at this interface.

As described above, the structure of using the light diffusing tape and the structure of roughening the surface of the light guide plate 1 differ greatly in the mechanism of light diffusion. Then, in the configuration using the light diffusion tape, specular reflection at the interface of the light guide plate 1 (acrylic) is suppressed, and a large amount of light is made incident on the transparent double-sided tape (adhesive layer) 51, and at the interface with the diffuse reflection substrate. Diffuse reflected. That is, with this configuration, it is possible to efficiently diffuse and reflect incident light. Further, in the light diffusion tape, the light reaching the white reflective layer 53 of the diffuse reflective base material is diffusely reflected by the white reflective layer 53. Therefore, when the light diffusing tape is used, the loss of light that occurs when roughening is performed can be suppressed to a small level.

When a light diffusing tape is used, as shown in FIG.
As shown in (a), if the edge portion formed by the bottom surface and the side surface of the protrusion 32 is separately covered with the two tapes 41 and 42, light leakage from this edge portion is caused and light is lost. There is a possibility of doing. Therefore, as shown in FIG. 13B, by covering this edge portion with one piece of tape 43, it is possible to reduce the loss of light and improve the work efficiency during manufacturing.

Here, the measurement results (objective data) for showing the effect of suppressing the uneven brightness by the light diffusing tape will be described.

In this measurement, a backlight is turned on in a dark room, and a backlight chassis (P chassis) is placed on the backlight.
The light guide plate 1 fitted in the guide plate 5 is installed, and as shown in FIG. 14, from the front surface (height 40 cm) of the light guide plate 1, as shown in FIG.
The uneven brightness generated in the vicinity of was observed. The WH50 manufactured by Lintec Co., Ltd. was used as the light diffusion tape that covers the protrusions 32. Further, as the light guide plate 1, a textured light guide plate for a 14-inch display (thickness 2.3 to 0.8 m
m) was used. Furthermore, as the inverter for the backlight, HIU-757 manufactured by Harrison Toshiba Lighting Co., Ltd. and a ballast capacitor 22pF were used. The lamp tube current is 6.0 mArms.

15 (a) to 15 (c) are explanatory views showing a measuring method (evaluation method; evaluation standard) of the luminance unevenness suppressing effect. That is, in this measurement, as shown in FIG. 15 (a), A point (length 15 mm, width 3) where the projection 32 (ear) of the light guide plate 1 shines (light is specularly reflected at the ear) and has a strong directivity.
mm) is present, and the brightness and darkness of the surrounding dark spots are clear, the brightness unevenness is severe (NG; XX
Or it is judged as x).

Further, as shown in FIG. 15B, although the above-mentioned bright spot becomes small (length 2 mm, width 1 m).
m) If it is clearly visible, it is determined that the brightness unevenness is large (NG; Δ or ▲). On the other hand, as shown in FIG. 15 (c), when the above-mentioned bright spot is almost invisible, the brightness unevenness is sufficiently small (OK;
○)

16 (a) to 16 (f) are explanatory views showing the outline of the sample used for this measurement and the measurement result. The sample # 1 shown in FIG. 16A has no light diffusion tape attached to any of the first side surface 61, the second side surface (tapered portion) 63, and the bottom portion 62 of the protrusion 32. In addition, sample # 2 shown in FIGS.
# 4 has only the first side surface 61, only the bottom portion 62,
The light diffusing tape is attached only to the second side surface 63.

Furthermore, the sample # shown in FIG.
In FIG. 5, light diffusion tapes are attached to the first side surface 61 and the second side surface 63 at two locations. Then, FIG. 16 (f)
Sample # 6 shown in FIG. 1 has a first side surface 61 and a second side surface 63.
In addition, an integrated light diffusing tape having a developed shape as shown in FIG. 17 is attached to three places of the bottom portion 62.

As a result of performing the above-mentioned measurement on these samples # 1 to # 6, the sample # 1 has a sharp luminance unevenness, and the sample # 4 shows almost no difference from the sample # 1. None, both samples were NG. Further, the uneven brightness was slightly improved in Sample # 3, and the uneven brightness was slightly improved in Samples # 2 and # 5, but it was still NG.

Then, in the sample # 6 having the light diffusing tape adhered to the three places, the uneven brightness was sufficiently improved and the result was OK. As described above, it can be said that it is preferable to use, as the light diffusing tape that covers the protruding portion 32, one having a one-piece shape that covers the three positions of the first side surface 61, the second side surface 63, and the bottom portion 62.

Further, the present liquid crystal display device 21 may be either a reflection type liquid crystal display device or a transmission type liquid crystal display device as long as it has the light guide plate 1.

The backlight chassis 5 is not limited to the frame shape as long as it has a shape to which the light guide plate 1 can be attached. For example, it may be a backlight chassis in which two rod-shaped members each having a groove portion are arranged.
Further, the chassis may be one in which two long plates are aligned, and the light guide plate 1 may be sandwiched between them.

The projection 32 may be integrally formed with the light guide plate 1, or may be provided separately after the light guide plate 1 is formed. In addition, the protruding portion 32 has the side portion 3
The shapes of 5.36 do not necessarily exist, and may have a curved shape protruding from the side surface of the light guide plate 1. Further, the protrusion 32 of the light guide plate 1 may be slightly raised (projected) from the side surface of the light guide plate 1 so that it can be fitted into the groove 33.

Further, the present liquid crystal display device 21 may have a structure in which the light guide plate 1 is provided with a groove portion and the backlight chassis 5 is provided with a protrusion portion so as to be fitted to each other. In this case, it is preferable that the boundary between the backlight chassis 5 and the protrusion and the side of the protrusion have a curved shape.

Further, in the present liquid crystal display device 21, the boundary portion 3
7. 38 and the side portions 35 and 36 may be provided with a reinforcing portion for improving the strength. Further, the shape of the reinforcing portion may be a shape that disperses the force applied to the boundary portions 37 and 38 and the side portions 35 and 36, and may be, for example, a curved surface shape or a flat surface shape. Further, the reinforcing portion may be a resin such as an adhesive, for example.

The side portions 35 and 36 and the boundary portion 37.3
8 does not need to have a curved shape, and the boundary portions 37 and 38
May be a curved surface. That is, the side portions 35 and 36 may be angular.

Further, in the present embodiment, the side portions 35.3
Reference numeral 6 denotes a side in the same direction as the thickness direction of the light guide plate 1, and these two sides (side sides 35 and 36) are R-processed.
However, the direction is not limited to this, and the side portion 35
-R processing may be performed on the side orthogonal to 36. Further, the apex of the protrusion 32 may be curved so as to absorb the load.

Further, in this way, with one tape 43, the side surface of the above-mentioned protrusion 32 and the dot pattern 31 are formed.
It is "optimization of the tape" that it can be attached to the formation surface. Further, the reflection sheet 6, the light guide plate 1, the diffusion sheet 7, the lens sheet 8 and the diffusion sheet 9 with the light-shielding print can be said to be optical sheets.

The present liquid crystal display device is a liquid crystal display device provided with a backlight device for irradiating a liquid crystal display panel with light using a light guide plate, and the above-mentioned light guide plate has a protrusion formed on its side surface. The part is fixed by fitting it into a groove provided in the frame of the backlight device, and further,
It can also be said that the boundary between the side surface and the protrusion is curved.

Further, the liquid crystal display device of the present invention is provided with a backlight for illuminating the liquid crystal display panel, and this backlight fixes the light guide plate and the light source arranged on the side surface of the light guide plate. A liquid crystal display device having a frame-shaped body, characterized in that the light guide plate has at least one or more protrusions, and a recessed portion paired with the protrusion is present in the frame-shaped body. It can be said that there is.

Also, in the light guide plate protrusion, the protrusion is rounded so that the light guide plate of the backlight can withstand impact.
It can be said that the shape is preferable.

Further, the light guide plate has a dot pattern for irradiating the surface of the liquid crystal display panel with the light emitted from the light source, and the side surface of the light guide plate protrusion and the dot pattern side are roughened. Therefore, it can be said that it is preferable to improve the brightness unevenness on the liquid crystal display panel.

It can also be said that it is preferable to improve brightness unevenness on the liquid crystal display panel by sticking a white tape having a diffuse reflection characteristic on the side surface of the light guide plate protrusion and the dot pattern side.

It can also be said that it is preferable that the side surface of the light guide plate projection and the tape having the diffuse reflection property to be stuck to the dot pattern side can be stuck to the side surface and the dot pattern side at the same time.

Further, as shown in FIG. 11 and the like, when the surface of the roughened light guide plate 1 (made of acrylic) is viewed microscopically, when the light reaches that surface, the angle of incidence and the It can be said that the refractive index (acryl and air layer) determines, according to the Fresnel's formula, whether the light is reflected or transmitted and then exits the light guide plate. Also, diffuse reflection means that the reflection that occurs at this time is uneven compared to the reflection on a flat surface,
Reflecting in some arbitrary direction, this repetition may be defined as diffuse. In addition, roughening may cause a problem that light is incident on the rough surface of the light guide plate and acryl is transmitted depending on the shape of the rough surface, and light is lost to the air layer, resulting in loss. .

[0104]

As described above, in the liquid crystal display device of the present invention (present liquid crystal display device), the liquid crystal display device is provided with the protruding portion protruding from the side surface of the light guide plate for guiding the backlight light to the liquid crystal display panel. Further, the liquid crystal display device is fitted in a groove provided in an inner wall of a frame for fixing the light guide plate, wherein a boundary portion between the protrusion and a side surface of the light guide plate has a curved shape.

According to this, in the present liquid crystal display device, the boundary between the above-mentioned protrusion and the light guide plate is curved.

Therefore, for example, even when a shock (force) is applied to the light guide plate, the shock applied to the protrusion is received over a wide area (curved surface). Therefore, the impact is dispersed without concentrating in a narrow range (boundary), and the light guide plate (boundary) is not cracked. Therefore,
The present liquid crystal display device has the effect of improving the impact resistance of the light guide plate.

Further, in the liquid crystal display device of the present invention, in addition to the above-mentioned structure, it is preferable that the surface of the protrusion is roughened to diffuse and reflect the backlight light. Alternatively,
It is preferable that a tape for diffusing and reflecting the backlight is attached to the surface of the protrusion.

The rough surface treatment or tape described above diffuses and reflects the light guided by the light guide plate. Therefore, for example, it is possible to prevent reflection (specular reflection) that occurs in the case of a projection having a mirror-like surface (specular reflection causes a portion where light does not reach the liquid crystal display panel, and a light with a strong directivity is generated). Cause uneven brightness).

That is, in the present liquid crystal display device, since the light incident on the protrusion is diffusely reflected by the tape or the roughened surface, the light can reach the entire area of the liquid crystal display panel. Therefore, it is possible to suppress the uneven brightness of the liquid crystal display panel caused by the portion where the light does not reach, and it is possible to improve the display quality.

Further, in the liquid crystal display device of the present invention, in addition to the above configuration, it is preferable that the above-mentioned tape has a single-sheet shape that covers the side surface of the projection and the incident surface of the backlight light.

For example, if a tape composed of two sheets is used,
One piece is attached to the side surface of the protrusion and the other piece is attached to the surface on the side where the light is incident, so that a gap may occur between the tapes.

However, by using the one-piece tape, it is possible to completely cover the light incident portion of the protrusion without generating a gap. Therefore, the light incident on the protrusions can be efficiently diffused and reflected, so that the uneven brightness of the liquid crystal display panel can be further suppressed, and the display quality of the liquid crystal display panel can be further improved.

Therefore, it is possible to further suppress the uneven brightness of the liquid crystal display panel and to improve the display quality of the liquid crystal display panel.

Further, the workability can be improved by using the tape having the shape of one sheet, as compared with the case of using the tape made of two sheets.

[Brief description of drawings]

FIG. 1 is a plan view showing a light guide plate and a backlight chassis of a liquid crystal display device (present liquid crystal display device) according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of the present liquid crystal display device.

3 is an overall view of the light guide plate of FIG. 1 described above.

FIG. 4 is a perspective view showing a dot pattern provided on a light guide plate.

FIG. 5 is a perspective view showing a light guide plate and a tape attached to the light guide plate.

FIG. 6 is a cross-sectional view of a Lintec reflective tape (WH50).

7 is a schematic view showing another example of the tape of FIG. 5 described above.

FIG. 8 is a plan view showing a light guide plate and a backlight chassis in a conventional liquid crystal display device.

9 is a plan view showing in detail a protrusion of the light guide plate in FIG.

10 (a) is an explanatory view showing a protrusion of the light guide plate, and FIGS. 10 (b) and 10 (c) show a rough surface of the protrusion shown in FIG. 10 (a). It is explanatory drawing which shows the cross section at the time of making it into, and when sticking a light diffusion tape on the surface.

FIG. 11 is an explanatory view showing an enlarged surface (cross section) of a roughened protrusion.

12 (a) is an explanatory diagram showing light reflection at the interface between the light guide plate and the air layer, and FIG. 12 (b) is
It is explanatory drawing which shows the state which light injects into a transparent double-sided tape in the interface of a light guide plate and a transparent double-sided tape (adhesive layer),
FIG. 12C is an explanatory diagram showing an enlarged view of the interface shown in FIG. 12B.

FIG. 13 (a) is an explanatory view showing a state where the edge portion formed by the bottom surface and the side surface of the protrusion is separately covered with two tapes, and FIG. 13 (b) shows this edge. It is explanatory drawing which shows the state which covered the part with one tape.

FIG. 14 is an explanatory diagram showing uneven brightness generated in the vicinity of a protrusion.

15A to 15C are explanatory diagrams showing a method for measuring the effect of suppressing uneven brightness (evaluation method; evaluation criteria).

16A to 16F are explanatory diagrams showing an outline of a sample used for measurement of a luminance unevenness suppressing effect and a measurement result thereof.

FIG. 17 is an explanatory diagram showing a developed shape of an integrated light diffusing tape.

[Explanation of symbols]

1 Light guide plate 2 fluorescent tube 5 Backlight chassis (frame) 11 Fluorescent tube device 12 Backlight exterior 13 Backlight device 21 Liquid Crystal Display 32 protrusion 33 Groove 35 side 36 side 37 Border 38 border 41 tapes 42 tape 43 tapes 51 transparent double-sided tape 52 PET (polyethylene terephthalate) 53 White reflective layer

Claims (4)

[Claims] 1. A liquid crystal display in which a protrusion protruding from a side surface of a light guide plate for guiding backlight light to a liquid crystal display panel is fitted in a groove provided in an inner wall of a frame for fixing the light guide plate provided in a liquid crystal display device. The liquid crystal display device according to claim 1, wherein a boundary portion between the protrusion and the side surface of the light guide plate has a curved shape. 2. The liquid crystal display device according to claim 1, wherein the surface of the protrusion is roughened to diffuse and reflect the backlight light. 3. The liquid crystal display device according to claim 1, wherein a tape for diffusing and reflecting the backlight is attached to the surface of the protrusion. 4. The liquid crystal according to claim 1, wherein the tape has a single-sheet shape that covers a side surface of a surface of the protrusion and an incident surface of the backlight light. Display device.