JPH0728049A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce the cost and thickness of the device by handling plural sheets of light diffusion sheets as if one sheet of light diffusion sheet to assemble the sheets and eliminating the need for separately disposing a light shielding plate, thereby simplifying operation at the time of assembling. CONSTITUTION:A flat planar light transmission plate 4 having light transmissibity is provided with a light source lamp 5 along its one end and a liquid crystal panel 1 to be irradiated with the light past the light transmission plate 4 from the light source lamp 5 is disposed on the light transmission plate 4. The light diffusion sheet part 3 which uniformly diffuses the light from the light transmission plate is interposed between the light transmission plate 4 and the liquid crystal panel 1. The light diffusion sheet part 3 consists of two sheets of the light diffusion sheets which are stuck and integrated with a blackish tacky adhesive applied on the sticking region R3 according to the non-effective display region of the liquid crystal panel 1 on the outer peripheral side of the respective light diffusion sheets.

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 back lighting.

[0002]

2. Description of the Related Art In recent years, STN (Super Twisted Nematic)
A liquid crystal display device using a liquid crystal panel composed of (1) is mainly a (color) notebook PC (Personal Com
It is being commercialized centering on the puter). As a backlight system for irradiating a liquid crystal panel from the back side, which is mounted on the liquid crystal display device, a light source lamp such as a cold cathode fluorescent lamp (CCFT) can be used as an acrylic resin having excellent light transmittance because it can be easily thinned. The so-called edge light type is mainly used, which is attached along the side end of a flat light guide plate made of, for example, and multiple-reflects light from a light source lamp in the light guide plate.

A liquid crystal display device equipped with an edge-light type backlight system is, for example, as shown in FIGS. 5 and 6, a liquid crystal panel 21 and a side end portion which illuminates the liquid crystal panel 21 from the rear side. The light guide plate 24 to which the light source lamp 25 is attached is supported by a three-part support housing 22. Further, between the liquid crystal panel 21 and the light guide plate 24, two light diffusion sheets 26 for uniformly diffusing the light emitted from the light guide plate 24.
26, and a light shield 23 that shields unnecessary light that is emitted to the ineffective display region R ₂ of the liquid crystal panel 21 among the lights that are emitted through the respective light diffusion sheets 26 are stacked in order from the bottom in the drawing. Has been done. The reason why two light diffusion sheets 26 are used is to improve the brightness of the backlight.
Further, the non-effective display area R ₂ in the liquid crystal panel 21 refers to an area on the outer peripheral side of the effective display area R ₁ in the liquid crystal panel 21.

[0004]

However, in the above-mentioned conventional structure, by using the two light diffusion sheets 26, 26, the brightness of the backlight can be increased, while the two light diffusion sheets are used. Since the sheets 26, 26 and the light shield 23 are laminated, the number of members is large, the assembling work is complicated, and the cost cannot be reduced. Further, since the number of laminated layers is large, the thickness of the device is increased, which causes a problem that the device cannot be thinned as expected. In particular, the number of sheets used in the light diffusion sheet 26 is not limited to two, and there are cases where three sheets or four sheets are stacked in order to further improve the brightness. In that case, the above-mentioned problems become more remarkable. Will appear.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an inexpensive and thin liquid crystal display device with a backlight having high brightness, which is easy to assemble the device. To do.

[0006]

In order to solve the above-mentioned problems, a liquid crystal display device according to a first aspect of the present invention has a light-transmitting property and a light guide plate having a light source attached along side edges. In the liquid crystal display device, the liquid crystal panel, to which light from the light source passes through the light guide plate, is arranged via a plurality of light diffusion sheets for diffusing the light from the light guide plate, It is characterized in that a plurality of light diffusion sheets are integrated by adhering the outer peripheral portion thereof with an adhesive.

In order to solve the above-mentioned problems, a liquid crystal display device according to a second aspect of the present invention is the liquid crystal display device according to the first aspect, in which the adhesive exhibits a blackish color and a liquid crystal panel It is characterized in that it is applied to a region of the light diffusion sheet corresponding to the non-effective display region of the liquid crystal panel so as to block light emitted to the non-effective display region on the outer peripheral side of the effective display region.

[0008]

According to the structure described in claim 1, since the plurality of light diffusion sheets are integrated by adhering the outer peripheral portion thereof with the adhesive, the plurality of light diffusion sheets are integrated. To
It can also be treated like a sheet of light diffusion sheet. As a result, the number of assembly work can be reduced, the assembly work can be simplified, and the work efficiency can be improved.
Eventually, the cost can be reduced.

According to a second aspect of the present invention, the pressure-sensitive adhesive exhibits a blackish color and blocks the light emitted to the non-effective display area on the outer peripheral side of the effective display area of the liquid crystal panel. Since the light diffusion sheet is applied to the area corresponding to the non-effective display area of the liquid crystal panel, the light which is going to pass through the area corresponding to the non-effective display area of the light diffusion sheet, the black adhesive layer Thus, the light is shielded by, and unnecessary light is not emitted to the ineffective display area of the liquid crystal panel. Therefore, unlike the conventional case, it is not necessary to separately provide a light shielding plate, the number of members is reduced, and the number of laminated layers is reduced. As a result, the work at the time of assembly is further simplified, the cost can be further reduced, and the thickness of the device is reduced by the thickness of the light shielding plate, and the device can be thinned.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS. As shown in FIG. 1 and FIG. 2, the liquid crystal display device of the present embodiment is formed in a flat plate shape and has a liquid crystal layer (not shown) sandwiched between a pair of substrates 1a and 1a, for example, STN (Super Twisted). Nema
tic) The liquid crystal panel 1 is used. Polarizing plates 1b and 1b are attached to the outer surface of the liquid crystal panel 1, and a drive circuit 1c for driving a liquid crystal layer is connected to the terminal lead-out portion on the end side.

On the upper surface side of the liquid crystal panel 1, there is arranged a first support housing 2a having a frame structure which is an integral body of three-part support housings. Panel 1
The outer peripheral side of the upper surface is covered. Incidentally, the first support housing 2
The support housing composed of a and second and third support housings 2b and 2c described later is made of SPCC, aluminum, acrylonitrile-butadienestyrene (ABS) resin, polycarbonate, or the like.

On the other hand, on the lower surface side of the liquid crystal panel 1, a light diffusing sheet portion 3 and a light guide plate 4 are laminated in this order, and a light guide plate is provided by a second support housing 2b arranged on the lower surface side. The outer peripheral side of the lower surface of 4 is supported. The second support casing 2b is fitted into the first support casing 2a.

The light guide plate 4 is a flat plate made of, for example, polymethylmethacrylate resin such as acryl having excellent light transmittance, and has a cold cathode for supplying light to the light guide plate 4 at one end thereof. A light source lamp 5 such as a tube (CCFT) is attached along the end. From the upper surface side to the rear surface side of the light source lamp 5, the first and second support housings 2a.
It is covered with a third support housing 2c fitted in each of b. Although not shown in the drawing, a scattering / reflecting pattern for efficiently scattering and reflecting light is formed on the lower surface of the light guide plate 4, and a reflector made of white polyethylene terephthalate (PET) or the like is provided. It is equipped.
With this structure, the light supplied from the light source lamp 5 is multiple-reflected inside the light guide plate 4, and the liquid crystal panel 1 is moved to the rear side via the light diffusion sheet portion 3 arranged above. It is designed to irradiate from.

As shown in FIG. 3, the light diffusing sheet portion 3 includes a light diffusing sheet 6 made of PET, polycarbonate or the like for efficiently and uniformly diffusing the light emitted from the light guide plate 4. A sheet, for example, an acrylic pressure-sensitive adhesive 7 in which a black dye is mixed, is adhered at the outer peripheral portion to be integrated. The sticking area (area shown by hatching in FIG. 1) R ₃ in each of the light diffusion sheets 6, that is, the application area of the adhesive 7 is an ineffective display on the outer peripheral side of the effective display area R ₁ of the liquid crystal panel 1. It is set in a region corresponding to the region R ₂ , and its thickness is several tens of μm. By setting in this way, the area corresponding to the ineffective display area R ₂ of the liquid crystal panel 1 in each light diffusion sheet 6 is covered with the adhesive layer 7 formed in the attachment area R _3. Therefore, of the light of the light source lamp 5 emitted through the light guide plate 4, unnecessary light emitted to the ineffective display region R ₂ of the liquid crystal panel 1 passes through the light diffusion sheet portion 3. The black adhesive layer 7 is shielded from light.

As described above, in the liquid crystal display device of this embodiment, the two light diffusing sheets 6 and 6 which are individually laminated in the conventional liquid crystal display device have the adhesive 7 on the outer peripheral portion. The light diffusion sheet portion 3 is integrated by being attached. Therefore, in the past, it was necessary to individually assemble and assemble, but it is now possible to handle and assemble as one light diffusion sheet 6.
As a result, the number of operations at the time of assembly can be reduced, the work efficiency can be improved, and the cost can be reduced.

Moreover, the pressure-sensitive adhesive 7 that adheres the light diffusion sheets 6 to each other has a blackish color, and
The sticking area (area shown by hatching in FIG. 1) R _{3 on} each light diffusion sheet 6 is set to an area corresponding to the non-effective display area R ₂ on the outer peripheral side of the effective display area R ₁ of the liquid crystal panel 1. Therefore, as described above, the adhesive layer 7 blocks unnecessary light emitted to the ineffective display region R _{2 of} the liquid crystal panel 1, and thus the light shielding plate is used as in the conventional case. There is no need to provide it separately. As a result, the number of members is reduced, the assembly work is further simplified, and the cost can be further reduced, and the light-shielding plate having a thickness of about 0.3 mm has an adhesive force of several tens of μm. Since the agent layer 7 is substituted, the thickness of the device is reduced by the thickness of the difference, and the device can be thinned.

Further, in the above embodiment, the light diffusing sheet portion 3 to which the two light diffusing sheets 6 and 6 are adhered is exemplified, but the present invention is not limited to this, and the three light diffusing sheets 6 are used.・ When using 6 ・ 6, as shown in Fig. 4,
The light diffusion sheet portion 3 ′ including the three light diffusion sheets 6 may be configured by laminating three sheets and adhering a predetermined area on the outer peripheral portion with the adhesive 7 in the same manner as described above.

Incidentally, the present invention is not limited to the above-mentioned one embodiment,
It goes without saying that many modifications and changes can be made within the scope of the claims of the present invention.

[0019]

As described above, in the liquid crystal display device according to the first aspect of the present invention, a plurality of light diffusion sheets are integrated by adhering the outer peripheral portions thereof with an adhesive. Therefore, a plurality of light diffusion sheets can be treated like one light diffusion sheet. As a result, the number of assembling work is reduced, the assembling work can be simplified, the working efficiency can be improved, and the cost can be reduced.

According to a second aspect of the present invention, the pressure-sensitive adhesive exhibits a blackish color and blocks the light emitted to the non-effective display area on the outer peripheral side of the effective display area of the liquid crystal panel. Since the light diffusion sheet is applied to the area corresponding to the non-effective display area of the liquid crystal panel, the light which is going to pass through the area corresponding to the non-effective display area of the light diffusion sheet, the black adhesive layer Thus, the light is shielded by, and unnecessary light is not emitted to the ineffective display area of the liquid crystal panel. Therefore, unlike the conventional case, it is not necessary to separately provide a light shielding plate, the number of members is reduced, and the number of laminated layers is reduced. As a result, the work at the time of assembling can be further simplified, the cost can be further reduced, and the thickness of the device can be reduced by the thickness of the light shielding plate, and the device can be thinned.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a main part of the liquid crystal display device.

FIG. 3 is a cross-sectional view of a light diffusion sheet portion included in the liquid crystal display device.

FIG. 4 is a cross-sectional view of a light diffusion sheet portion included in a liquid crystal display device according to another embodiment of the present invention.

FIG. 5 is an exploded perspective view of a conventional liquid crystal display device.

FIG. 6 is a cross-sectional view of a main part of a conventional liquid crystal display device.

[Explanation of symbols]

1 Liquid crystal panel 3 Light diffusion sheet section 4 Light guide plate 5 Light source lamp 6 Light diffusion sheet 7 Adhesive R ₁ Effective display area R ₂ Ineffective display area R ₃ Adhesive area

Claims (2)

[Claims] 1. A light guide plate which is light-transmissive and to which a light source is attached along side edges, and a liquid crystal panel which is irradiated with light passing through the light guide plate from the light source are provided from the light guide plate. In a liquid crystal display device arranged via a plurality of light diffusing sheets for diffusing light, the plurality of light diffusing sheets are integrated by adhering the outer peripheral portion thereof with an adhesive. A liquid crystal display device characterized in that 2. The non-effective liquid crystal panel in the light diffusion sheet so that the pressure-sensitive adhesive exhibits a blackish color and blocks the light irradiated to the non-effective display area on the outer peripheral side of the effective display area of the liquid crystal panel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is applied to an area corresponding to a display area.