JP2000131691A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent display unevenness due to a warp of a COB(chip-on board) substrate from occurring in a liquid crystal display panel without interposing a spacer between the COB substrate and a light transmission plate. SOLUTION: This liquid crystal display device contains the COB substrate 3 that a liquid crystal driving electronic parts is mounted directly on one side surface, a side light type backlight unit and the liquid crystal display panel 1, and is constituted so that the light transmission plate 20 of the backlight unit is arranged on the other side surface side of the COB substrate 3, and the liquid crystal display panel 1 is arranged on the light transmission plate 20, and these respective members are overlapped integrally in a casing 5. In such a case, the parts becoming ribs 24a-24c abutted on the peripheral part of the COB substrate 3 remains on the surface side opposite to the COB substrate 3 of the light transmission plate 20, and a recessed part 23 is formed.

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 in which a liquid crystal display panel, a backlight unit, and a COB substrate are superposed and integrated in a housing.

[0002]

2. Description of the Related Art In a relatively small liquid crystal display device,
A COB substrate is used as a circuit board for driving a liquid crystal. The COB (chip on board) is a method in which electronic components such as an IC chip are directly mounted on a printed circuit board. A conventional example of a display device is schematically shown.

The liquid crystal display device will be described in accordance with the assembling procedure. First, the light guide plate 2 of the backlight unit is temporarily fixed to the back side of the liquid crystal display panel 1 via a double-sided adhesive tape 4a. The COB substrate 3 is temporarily fixed on the back surface via a double-sided adhesive tape 4b. The backlight unit used here is of a sidelight type, and although not shown, a light source is provided on the side of the light guide plate 2.

After the module thus temporarily fixed is arranged in the outer casing 5 so as to face the display window 5a via the cushioning material 6a, the cushioning material 6 is placed on the back side of the module.
The printed circuit board 7 is covered with a predetermined pressure via b. Thereby, the liquid crystal display panel 1, the light guide plate 2, and the C
The OB substrates 3 are integrated so as to be overlapped.

[0005]

As shown in FIG. 5, a liquid crystal driving IC chip 8 is mounted on one side of the COB substrate 3 and its electrode terminals are connected by wire bonding or the like. Although connected to the connection terminal on the substrate side, in any case, after the connection, a liquid resin is applied to the IC chip 8 so as to cover the entire surface, and the IC chip 8 is sealed in the resin material 9.

There is no problem when the COB substrate 3 is relatively thick and has high rigidity. However, when the COB substrate 3 is thin and easy to bend, the COB substrate 3 is warped due to joining of different materials. I do. For example, when the resin material 9 shrinks due to its curing, as shown by the imaginary line in FIG. 6, warpage occurs at both ends 3a, 3a of the COB substrate 3.

[0007] This means that the COB substrate 3 is connected to both ends 3
When supported on the sides a and 3a, it means that the central portion of the substrate expands upward. Therefore, when the COB substrate 3 having the warp thus generated is incorporated into the outer casing 5 and a tightening force is applied to the both ends 3a, 3a from the printed circuit board 7 side, the center portion of the liquid crystal display panel 1 relatively moves. The light is pressed by the COB substrate 3 via the light guide plate 2, which causes display unevenness near the center of the liquid crystal display panel 1.

In the prior art, for example, a spacer is interposed between the COB substrate 3 and the light guide plate 2 so as to secure a predetermined gap between them. Cost increase is inevitable. In addition, since the thickness of the assembly module is increased due to the interposition of the spacer, the thickness of the assembly module is hindered.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and its object is to provide a CO
A liquid crystal display device in which even if the B substrate is warped, display irregularities due to the warpage of the COB substrate do not occur in the liquid crystal display panel, particularly without interposing a spacer between the COB substrate and the light guide plate. Is to provide.

According to the present invention, an object of the present invention includes a COB substrate having one surface directly mounted with a liquid crystal driving electronic component, a sidelight type backlight unit, and a liquid crystal display panel. A light guide plate of the backlight unit is arranged on the other surface side of the COB substrate, and the liquid crystal display panel is arranged on the light guide plate, and these members are integrated in a housing (for example, an exterior housing). In the liquid crystal display device superimposed on the above, the COB of the light guide plate
On the surface facing the substrate, leaving a portion serving as a rib that comes into contact with the peripheral portion of the COB substrate, form a slope with a predetermined inclination angle from the light receiving surface side of the light guide plate toward the facing surface facing the same. This is achieved by forming a recess.

In this case, the rib is preferably provided along each side of the COB substrate.
What is necessary is just to provide along the two opposing sides of the OB substrate.

[0012] The object of the present invention is to provide a light guide plate comprising:
The center of the light guide plate extends from one side of the light guide plate to the other side, leaving a portion serving as a rib abutting on the periphery of the COB substrate on the surface side facing the B substrate. It is also achieved by continuously forming a curved concave portion with a predetermined curvature so that the portion becomes a valley.

As described above, in the case where the concave portion having a curved surface is formed in the light guide plate, a light source is disposed on each of the opposing surfaces of the light guide plate, and a rib is provided on the surface side on which the light source is not disposed. Is preferably provided along each side.

In any aspect, according to the present invention,
Since the concave portion is formed in the light guide plate, even if the central portion of the COB substrate swells upward, the liquid crystal display panel has a C
The display unevenness of the liquid crystal display panel, which has conventionally been a problem, is eliminated without being pressed by the OB substrate.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

FIG. 1 is a schematic sectional view of the first embodiment, and
The state where the light guide plate 20 and the liquid crystal display panel 1 are respectively stacked on the G substrate 3 is shown. After these members are temporarily fixed with a double-sided adhesive tape, they are housed in the exterior housing 5 previously illustrated in FIG. 5 and integrally assembled. Although a backlight light source is provided, FIG. 1 does not show the exterior housing and the backlight light source for convenience of drawing.

The light guide plate 20 is made of a synthetic resin plate having a rectangular shape and a predetermined thickness, such as polycarbonate. FIG. 2 shows the light guide plate 20 on its rear surface (the surface facing the COG substrate 3). The perspective view seen from FIG.

In FIG. 2, if the right side surface is a light receiving surface 21 to which light from a backlight light source is irradiated,
On the back surface of the light guide plate 20, there is formed a slope-shaped recess 23 having a predetermined inclination angle and a downward slope from the light receiving surface 21 side to the facing surface 22 side facing the light receiving surface 21 side.

The periphery of the concave portion 23 is kept at its original thickness as a rib contacting the periphery of the COG substrate 3. In the first embodiment, ribs 24a and 24b are provided on two sides of the recess 23 along the slope direction, and a rib 24c is also provided on the opposing surface 22 side of the light receiving surface 21. That is, three ribs 2 are formed along three sides of the light guide plate 20.
Although ribs 4a to 24c are provided, ribs may be left on the light receiving surface 21 side.

The light guide plate 20 is placed such that the ribs 24a to 24c abut on the periphery of the COG substrate 3 with the back surface side on which the recess 23 is formed facing downward.
In consideration of the warpage of the OG substrate 3, the central portion thereof is formed in the concave portion 23.
It is so deep that it does not touch it. In addition, this first
In the embodiment, a reflection plate (including a film-like member) 25 is provided in the recess 23.
Is pasted.

Therefore, the liquid crystal display panel 1, the light guide plate 2
When the COG substrate 3 and the COG substrate 3 are superposed and integrated in the exterior housing 5 as shown in FIG.
Even if the substrate 3 is warped such that its central portion swells toward the light guide plate 20, no pressure due to the warp is applied to the liquid crystal display panel 1 and display unevenness does not occur.

Next, the second embodiment of the present invention will be described with reference to FIGS.
An example will be described. FIG. 3 shows FIG. 1 of the first embodiment.
FIG. 4 is a schematic sectional view of the light guide plate 40 used in the second embodiment viewed from the back side thereof.

Also in the second embodiment, the light guide plate 40 is made of the same material as the light guide plate 20 of the first embodiment and is a rectangular plate having a predetermined thickness. A groove-shaped (gutter-shaped) concave portion 41 is formed.

That is, the concave portion 41 has opposite side surfaces 42,
The light guide plate 43 is formed of a series of curved surfaces with a predetermined curvature so that the central portion of the light guide plate 40 becomes a valley from one side to the other side.

In the second embodiment, a backlight light source (not shown) is arranged on the side of each of the side surfaces 42 and 43, respectively. That is, the side surfaces 42 and 43 are light receiving surfaces,
On the other side, the ribs 44a and 44b that come into contact with the periphery of the COG substrate 3 are left with the original thickness. As in the first embodiment, ribs may be left on the side surfaces 42 and 43 as light receiving surfaces.

As described above, also in the second embodiment,
Since the concave portion 41 is formed in the central portion on the rear surface side of the light guide plate 40, even if the COG substrate 3 is warped such that the central portion swells toward the light guide plate 40, the liquid crystal display panel 1 is warped. Is not applied, and display unevenness does not occur.

It should be noted that the slope surface of the concave portion 23 in the first embodiment may be a gentle curved surface. Also, the concave portion 41 in the second embodiment may be a collective surface including a plurality of curved surfaces having different curvatures or a collective surface including a plurality of flat surfaces having different inclination angles.

[0028]

As described above, according to the present invention,
When the liquid crystal display panel, the light guide plate, and the COB substrate are overlapped and integrated in the housing, a concave portion is formed on the surface of the light guide plate facing the COB substrate, leaving a portion serving as a rib contacting the periphery of the COB substrate. COB by forming
Without interposing a spacer between the substrate and the light guide plate,
Display unevenness due to warpage of the COB substrate of the liquid crystal display panel can be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the light guide plate in the first embodiment as viewed from the back side.

FIG. 3 is a schematic sectional view showing a second embodiment of the present invention.

FIG. 4 is a perspective view of the light guide plate in the second embodiment as viewed from the back side.

FIG. 5 is a schematic sectional view showing a conventional example.

FIG. 6 is a side view for explaining the warpage of the COB substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 3 COB board 5 Outer housing 20, 40 Light guide plate 21, 42, 43 Light receiving surface 33, 41 Recess 24a-24c, 44a, 44b Rib

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G02F 1/1345 G02F 1/1345 F-term (Reference) 2H038 AA55 BA06 2H089 HA40 JA10 QA16 TA18 TA20 2H091 FA14Z FA23Z FA41Z FB02 FD13 LA18 2H092 GA50 GA51 NA01 PA12 PA13

Claims (4)

[Claims] 1. A COB substrate having a liquid crystal driving electronic component directly mounted on one surface, a sidelight type backlight unit, and a liquid crystal display panel,
A liquid crystal display device in which the light guide plate of the backlight unit is arranged on the other surface side of the substrate, the liquid crystal display panel is arranged on the light guide plate, and these members are integrally overlapped in a housing. In the above, the light guide plate faces from the light receiving surface side of the light guide plate to the opposing surface side facing the COB substrate, leaving a portion serving as a rib abutting on a peripheral portion of the COB substrate. A liquid crystal display device provided with a slope-shaped concave portion formed at a predetermined inclination angle. 2. The liquid crystal display device according to claim 1, wherein the rib is provided along at least two opposing sides of the COB substrate. 3. A COB substrate having a liquid crystal driving electronic component directly mounted on one surface, a sidelight type backlight unit, and a liquid crystal display panel,
A liquid crystal display device in which the light guide plate of the backlight unit is arranged on the other surface side of the substrate, the liquid crystal display panel is arranged on the light guide plate, and these members are integrally overlapped in a housing. In the above, the light guide plate has, on a surface side facing the COB substrate, a portion serving as a rib which comes into contact with a peripheral portion of the COB substrate, and one side surface side of the light guide plate facing each other and the other side surface. A liquid crystal display device comprising a curved surface-shaped concave portion continuously formed with a predetermined curvature so that a central portion of the light guide plate becomes a valley toward a side surface of the liquid crystal display device. 4. The light guide plate according to claim 3, wherein a light source is disposed on each of the opposing surfaces of the light guide plate, and the rib is provided along each side of the surface on which the light source is not disposed. The liquid crystal display device as described in the above.