JPH09211227A - Liquid crystal display module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display module with which the display with high quality is made possible by eliminating the variation in the gap between prism sheets superposed on each other. SOLUTION: This liquid crystal display module has a liquid crystal panel 5 and a back light 8 installed on the rear surface of the liquid crystal panel 5. The back light 8 has a light transmission body 1 and at least the two prism sheets 2a, 2b superposed on each other between the light transmission body 1 and the liquid crystal panel 5. Tacky adhesive beads 7 are dispersed between the prism sheets 2a and 2b to make the gap uniform.

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 module, and more particularly, to a liquid crystal display in which a plurality of prism sheets constituting a backlight installed on a lower surface of a liquid crystal panel have a uniform overlapping gap to avoid generation of interference fringes. Regarding modules.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as flat type display devices for displaying various images or characters.

This liquid crystal display device has a liquid crystal panel in which a liquid crystal layer is sandwiched between at least two transparent electrode substrates, and a liquid crystal display module in which a backlight for illumination is incorporated on the lower surface of the liquid crystal panel, which is required for driving. It is configured by integrating a printed circuit board on which circuits and the like are mounted.

In general, the backlight is provided with a transparent plate-shaped light guide, and at least two prism sheets (Fresnel lenses) superposed between the light guide and the liquid crystal panel. A cold cathode fluorescent lamp is arranged at one edge of the light guide, and light from the cold cathode fluorescent lamp is illuminated on the liquid crystal panel by the light guide as a planar light source.

FIG. 6 is a schematic view for explaining the schematic structure of a liquid crystal display module of this type. 1 is a light guide made of a transparent resin plate, 2 is a prism sheet, 2a is a lower prism sheet, and 2b is an upper side. Prism sheet, 3 is a cold cathode fluorescent lamp,
Reference numeral 4 is a lamp projection sheet, 5 is a liquid crystal panel, and 6 is a reflector. Reference numeral 22 represents the entire backlight.

In the figure, the backlight 22 is installed on the lower surface of the liquid crystal panel 5 and has a function of illuminating the liquid crystal panel from the back surface. That is, the light from the cold cathode fluorescent lamp 3 is directed upward by the light guide plate 1 and illuminates the liquid crystal panel 5 via the prism sheet 2.

The lamp reflection sheet 4 is for effectively utilizing the light emission of the cold cathode fluorescent lamp 3 to achieve high brightness, and the reflection plate 6 directs the light propagating through the light guide plate 1 toward the liquid crystal panel 5. It has the function of reflecting.

A light distribution uniformizing means such as a dot pattern is formed on the lower surface of the light guide plate 1 by printing or the like.

The prism sheet 2 has a large number of grooves formed in one direction on one surface of the transparent sheet, corrects the directing direction of the light from the light guide plate 1 and makes the light incident from the lower surface of the liquid crystal panel 5 at an acute angle. A plurality of (usually two) prism sheets 2a and 2b having an action are stacked and used so that their groove directions intersect at an angle.

For example, Japanese Patent Application Laid-Open No. 1-37801 discloses the prior art relating to this type of prism sheet.
Publication No.

[0011]

As a backlight for a liquid crystal display module, at least two prism sheets which are superposed as described above are used. Since the two prism sheets are simply stacked and installed, and since each prism sheet is a thin sheet-shaped member, there is variation in the gap between the stacked prism sheets.

The nonuniformity of the gap causes optical interference, causes unevenness in brightness of the liquid crystal panel, so-called Newton's ring, and causes deterioration of display quality.

Further, if there is a space between the stacked prism sheets, there is a problem that dust enters and adversely affects the displayed image.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a liquid crystal display module capable of high-quality display by eliminating the variation in the gap between the stacked prism sheets.

[0015]

In order to achieve the above object, the first invention according to claim 1 is a liquid crystal display module comprising a liquid crystal panel and a backlight installed on the lower surface of the liquid crystal panel. The backlight has a light guide body and at least two prism sheets that are superposed between the light guide body and the liquid crystal panel, and adhesive beads are dispersed between the prism sheets. Characterize.

A second aspect of the present invention is characterized in that one of the superposing surfaces of the superposed prism sheets is a prism groove forming surface.

Further, the third invention according to claim 3 is
It is characterized in that the superposed surfaces of the superposed prism sheets are flat surfaces.

It should be noted that one or both of the above-mentioned prism sheets are superposed with their grooved surfaces facing either the light guide side or the liquid crystal panel side.

Therefore, the adhesive beads are inserted between the groove surface of one prism sheet and the flat surface of the other prism sheet, between the respective groove surfaces, or between both flat surfaces.

The adhesive beads are prepared by dispersing known resin beads used for securing the cell gap of the liquid crystal panel in a transparent adhesive or other adhesive, or the beads themselves are made of an adhesive material. The formed one can be used.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIG. 1 is an exploded perspective view of a main part for explaining a first embodiment of a liquid crystal display module according to the present invention, in which 1 is a light guide plate, 1a is a light entrance surface, 1b is a light exit surface, and 2a is a first light exit surface. The prism sheet, 2b is the second prism sheet, 2a ', 2
b'is a groove, 3 is a cold cathode fluorescent lamp (lamp), 4 is a lamp reflection sheet (lamp reflector), 5 is a liquid crystal panel, 7 is adhesive beads, and 22 is a backlight. In FIG. 6, the reflector of FIG. 6 is not shown.

In FIG. 1, the backlight 22 comprises a light guide plate 1, prism sheets 2a and 2b, a cold cathode fluorescent lamp (lamp) 3 provided at one edge of the light guide plate 1, and a lamp reflection sheet 4.

The backlight 22 is installed on the back surface of the liquid crystal panel 5 so that the light incident from the light entrance surface 1a of the light guide 1 propagates inside the light guide plate 1 and is emitted upward from the light exit surface 1b. To form a planar light source.

The surface light source illuminates the liquid crystal panel 5 from the back side to visualize an image or the like formed on the liquid crystal panel.

In this embodiment, the first prism sheet 2
a is a groove 2a 'on its upper surface, that is, the surface facing the liquid crystal panel.
The second prism sheet 2b has a groove 2b 'on its lower surface, that is, on the side of the light guide plate 1, and the two are superposed.

The extending direction of the groove 2a 'of the first prism sheet 2a is arranged so as to be orthogonal to the axial direction of the cold cathode fluorescent lamp 3, and the extending direction of the groove 2b' of the second prism sheet 2b is the cold cathode. It is arranged parallel to the axial direction of the fluorescent lamp 3.

Therefore, both prism sheets 2a and 2b
Are superposed with the surfaces on which the grooves 2a ′ and 2b ′ are formed facing each other, and the adhesive beads 7 are placed on the superposed surfaces.
Are dispersed to make the gap between them uniform.

The pressure-sensitive adhesive beads 7 preferably have such a diameter that the grooves of both prism sheets are filled and the vertices of the grooves have the same height. The adhesive beads 7 are formed by dispersing plastic beads in an adhesive (or an adhesive) to impart adhesiveness, and spraying the beads between both prism sheets 2a and 2b, or an adhesive (or an adhesive in which plastic beads are dispersed). It is dispersed between both prism sheets 2a and 2b in a state of being dispersed in the agent).

It is also possible to adopt a method in which the adhesive beads 7 having adhesiveness themselves are applied between the prism sheets 2a and 2b.

The plastic beads may be of the known type used to set the cell gap of liquid crystal panels.

Then, both prism sheets 2a and 2b, which are superposed through the adhesive beads, are uniformly pressed by an appropriate pressing means to make the gap between them uniform.

The two prism sheets thus bonded together are inserted between the backlight 22 and the liquid crystal panel 5 to form a liquid crystal display module.

According to this embodiment, it is possible to obtain a high-quality liquid crystal display module free from variations in the gap between the stacked prism sheets and free from interference fringes such as uneven brightness and Newton's rings.

FIG. 2 is a sectional view of an essential part for explaining a second embodiment of the liquid crystal display module according to the present invention, and the same reference numerals as those in FIG. 1 correspond to the same parts. The illustration of the liquid crystal panel is omitted.

In this embodiment, the first prism sheet 2a is used.
The groove surface of the second prism sheet 2 faces the light guide plate 1.
The groove surface of b is faced to the first prism sheet 2a, and the adhesive beads 7 are inserted between the two to form a uniform gap.

As in the above embodiment, the grooves of the first prism sheet 2a are arranged so that the extending direction of the grooves is orthogonal to the axial direction of the cold cathode fluorescent lamp 3 and the second prism sheet 2b is formed.
The extending direction of the groove is arranged parallel to the axial direction of the cold cathode fluorescent lamp 3.

Also in this embodiment, the gap variation between the stacked prism sheets is eliminated, and a high quality liquid crystal display module free from interference fringes such as uneven brightness and Newton rings can be obtained.

FIG. 3 is a sectional view of an essential part for explaining a third embodiment of the liquid crystal display module according to the present invention, and the same reference numerals as those in FIG. 2 correspond to the same parts. The illustration of the liquid crystal panel is omitted.

In this embodiment, the first prism sheet 2a is used.
The groove surface of the second prism sheet 2b is directed toward the liquid crystal panel, and the groove surface of the second prism sheet 2b is also directed toward the liquid crystal panel, and the adhesive beads 7 are inserted between the two to form a uniform gap.

The extending direction of the groove of the first prism sheet 2a is arranged so as to be parallel to the axial direction of the cold cathode fluorescent lamp 3, and the extending direction of the groove of the second prism sheet 2b is the cold cathode fluorescent lamp. It is arranged so as to be orthogonal to the axial direction of 3.

Also according to this embodiment, the gap variation between the superimposed prism sheets is eliminated, and a high quality liquid crystal display module without interference fringes such as uneven brightness and Newton rings can be obtained.

FIG. 4 is a sectional view of an essential part for explaining a fourth embodiment of the liquid crystal display module according to the present invention, and the same reference numerals as those in the above embodiment correspond to the same parts. The illustration of the liquid crystal panel is omitted.

In this embodiment, the first prism sheet 2a is used.
The groove surface of the second prism sheet 2b is directed toward the liquid crystal panel, and the groove surface of the second prism sheet 2b is directed toward the first prism sheet 2a.
Adhesive beads 7 are inserted between the two to form a uniform gap.

The extending direction of the grooves of the first prism sheet 2a is arranged so as to be orthogonal to the axial direction of the cold cathode fluorescent lamp 3, and the extending direction of the grooves of the second prism sheet 2b is the cold cathode fluorescent lamp. It is arranged so as to be parallel to the axial direction of 3.

Also in this embodiment, it is possible to obtain a high-quality liquid crystal display module free from variations in the gap between the stacked prism sheets and free from interference fringes such as uneven brightness and Newton's rings.

FIG. 5 is a developed perspective view for explaining the overall structure of a liquid crystal display device formed by using the liquid crystal display module according to the present invention.
Is a lamp (cold cathode fluorescent lamp), 4 is a lamp reflection sheet, 5
Is a liquid crystal panel, 10 is an upper frame, 11 is a lower frame,
12 is a display window, 13 is a spacer, 14 is an adhesive tape, 1
6 is a cut-and-raised piece, 17 is a nail, 18 is a ground pad, 19
Is a nail holder, 20 is a drive circuit board, 22 is a backlight, 2
3 is an intermediate frame, 24 and 25 are notches, 26, 27,
28 and 29 are cutout parts, 31 is a lamp cover, and 32 is the entire liquid crystal display device.

In FIG. 1, the liquid crystal panel 5 is provided with a light guide 1 and a lamp 3 on its lower surface, and is set in an intermediate frame 23 in which a backlight 22 is laminated together with a prism sheet 2, and an upper frame 10 and a lower frame 11 are formed. It is pinched and fixed.

Cut and raised piece 16 formed on the upper frame 10.
Contacts the ground pad 18 formed on the drive circuit board 20, and the claw 17 is a claw receiver 19 formed on the lower frame 11.
And the upper frame 10 and the lower frame 11 are fixed.

The upper frame 10 and the liquid crystal panel 5 are fixed by the adhesive tape 14. The cutouts 26 and 27 are provided at positions symmetrical to a line orthogonal to the central portion of the backlight, and the cutouts 28 and 29 are provided in the longitudinal direction of the lamp 3. Further, notches 24 and 25 are provided in the lower portions of both ends of the lamp 3.

The upper frame 10 is, for example, a steel plate having a thickness of 0.8 mm, and the lower frame 11 is a steel plate or has a considerable thickness, for example, 0.
It is composed of 5 mm thick aluminum.

The liquid crystal display device 32 is sandwiched and fixed by the upper frame 10 and the lower frame 11 in the order shown in FIG. The lamp 3 is installed on one end side of the intermediate frame 23, and the emitted light is reflected by the lamp reflection sheet 4 into the backlight 2.
2 is directed to the light guide 1 side. In addition, lamp 3
The lamp cover 31 installed on the liquid crystal panel 5 side prevents light from leaking upward.

The spacer 13 is provided in a recess formed in the intermediate frame 23, and the light guide 1 and the prism sheet 2 are provided.
The display area is defined by being interposed between the liquid crystal panel 5 and the liquid crystal panel 5.

As described above, the upper frame 10 is formed of a stainless thin plate, and the lower frame 11 is formed of an aluminum thin plate. Then, at least a pair of cutout portions 26, 27 are provided at positions symmetrical to a line orthogonal to the central portion of the lamp 3 over at least the region of the liquid crystal panel 5 in the direction orthogonal to the lamp 3 of the lower frame 11, and the lamp 3 Immediately below the lamp 3, at least two cutouts 28, 29 provided in the longitudinal direction of the lamp 3 and notches 24, 25 provided at lower portions of both ends of the lamp 3 are formed.

According to the above structure, the liquid crystal display device can be made thin and lightweight without lowering its rigidity, and at least the liquid crystal panel 5 can be arranged in the direction orthogonal to the lamp 3.
Cutouts 26, 27 provided at positions symmetrical with respect to a line orthogonal to the central portion of the lamp 3 over the region, and a cutout 2 provided in the longitudinal direction of the lamp 3 just below the lamp 3.
8, 29 and the notches 24, 25 provided in the lower portions of both ends of the lamp 3 improve the heat radiation effect, form a uniform temperature distribution on the entire surface of the liquid crystal panel 5, and prevent the occurrence of display unevenness. .

Since the lamp 3 is driven at a high frequency, a current flows from the lamp 3 to the lower frame 11 via the stray capacitance between the lower frame 11 and the lamp 3. This current is called "leakage current", but this "leakage current"
The amount of current contributing to the lighting of the lamp 3 is reduced by that much, and the brightness is reduced.

Further, the lamp 3 generates heat when it is turned on for a long time, and the temperature in the vicinity thereof rises with respect to the outside air. Therefore, unless some measures are taken, the heat directly affects the liquid crystal panel 5, The temperature distribution of the liquid crystal panel cannot be made uniform. Therefore, in the above embodiment, the cutout portions 28 and 29 are provided.
To prevent a decrease in luminance due to the "leakage current" and to make the temperature distribution of the liquid crystal panel uniform, thereby preventing the occurrence of display unevenness. Further, the cutouts 28 and 29 prevent the brightness from being lowered due to the thermal diffusion of the lamp 3. Lamp 3
In particular, both end portions of (1) are parts that cause a decrease in luminance due to a decrease in temperature, and it is necessary to raise the temperature within a range in which the uniform temperature distribution of the liquid crystal panel 5 can be maintained. Therefore, the notches 24 and 25 are provided to make the temperature distribution of the liquid crystal panel 5 uniform and prevent the luminance from decreasing. Functionally, the same effect as the cutouts 28 and 29 is produced.

In the liquid crystal display device having such a structure, by using the above-described prism sheet according to the present invention as the backlight, generation of optical interference fringes such as uneven brightness and Newton's rings is suppressed, and the prisms are superposed. It is possible to provide an image display device that can obtain high-quality image display without causing dust to enter between the sheets to deteriorate display quality.

[0059]

As described above, according to the present invention,
In a liquid crystal display module using a laminated prism sheet as a constituent material of a backlight for illuminating a liquid crystal panel, the gap between the laminated prism sheets is made uniform, and dust is prevented from entering a high gap. A liquid crystal display module having improved display quality can be obtained.

[Brief description of drawings]

FIG. 1 is a main part exploded perspective view illustrating a first embodiment of a liquid crystal display module according to the present invention.

FIG. 2 is a sectional view of an essential part for explaining a second embodiment of the liquid crystal display module according to the present invention.

FIG. 3 is a cross-sectional view of essential parts for explaining a third embodiment of the liquid crystal display module according to the present invention.

FIG. 4 is a sectional view of an essential part for explaining a fourth embodiment of the liquid crystal display module according to the present invention.

FIG. 5 is an exploded perspective view illustrating the overall configuration of a liquid crystal display device configured using the liquid crystal display module according to the present invention.

FIG. 6 is a schematic diagram illustrating a schematic configuration of a liquid crystal display module.

[Explanation of symbols]

 1 Light guide plate 1a Light entrance surface 1b Light exit surface 2a First prism sheet 2b Second prism sheet 2a ', 2b' Groove 3 Cold cathode fluorescent lamp (lamp) 4 Lamp reflection sheet (lamp reflector) 5 Liquid crystal panel 7 Adhesive beads 10 Upper Frame 11 Lower Frame 12 Display Window 13 Spacer 14 Adhesive Tape 16 Cutting and Raising Piece 17 Claw 18 Ground Pad 19 Claw Receiving 20 Drive Circuit Board 22 Backlight 23 Intermediate Frame 24, 25 Notch 26, 27, 28, 29 Cutout Part 31 Lamp cover 32 Liquid crystal display device as a whole.

Claims (3)

[Claims] 1. A liquid crystal display module comprising a liquid crystal panel and a backlight installed on the lower surface of the liquid crystal panel, wherein the backlight is a light guide body, and is stacked between the light guide body and the liquid crystal panel. A liquid crystal display module comprising at least two prism sheets combined together, wherein adhesive beads are dispersed between the prism sheets. 2. The liquid crystal display module according to claim 1, wherein one of the superposed surfaces of the superposed prism sheets is a prism groove forming surface. 3. The liquid crystal display module according to claim 1, wherein the superposed surfaces of the superposed prism sheets are flat surfaces.