JPH0695110A - Back light for liquid crystal and liquid crystal module formed by using the same - Google Patents

Abstract

PURPOSE:To prevent the deformation by expansion of a protective plate mounted to the surface of a display frame of a module case housing a liquid crystal panel by mounting this protective plate in such a manner that the protective plate can be expanded and contracted with respect to the display frame. CONSTITUTION:The outer part of the display frame 16 of the module case 13 is tapped and is provided with mounting holes in the positions of the protective plate 14 facing the positions of the taps. These mounting holes are opened in two steps, large and small and are formed larger than the size of mounting screws 17. After the liquid crystal panel 11 and the back light 12 are housed in the module case 13, the protective panel 14 is placed right on the display frame 16 of the module case 13 and is mounted by the set screws 17. The protective plate 14 mounted in such a manner is expandable and contractable laterally and, is, therefore, deformed by moisture absorption, by which the protective plate is brought into contact with the liquid crystal panel. The impairment of the display quality is thus prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal backlight and a liquid crystal module using the same.

[0002]

2. Description of the Related Art As shown in FIGS. 5A, 5B, and 5C, a conventional liquid crystal backlight (hereinafter referred to as a backlight) has a plurality of cold cathode types or hot cathode types. The fluorescent lamps 1 are arranged and fixed by the lamp holder 2, the lighting curtain 3 is arranged above the fluorescent lamp 1, and the diffusion plate 4 is arranged closely on the lighting curtain 3. A frame-shaped face board 5 is arranged adjacent to each periphery of the diffusion plate 4. Further, a reflector 6, an inverter 7, and an inverter case 8 are arranged below and in the lateral direction of the fluorescent lamp 1.

Next, the operation of the backlight will be described.

The high-frequency high-voltage pulse output from the inverter 7 turns on the fluorescent lamp 1 and the emitted light is
The reflector 6 moves upward. Further, the lighting curtain 3 and the diffusing plate 4 make the brightness uniform, and
The light emitting surface is almost the same over the entire area and the face board 5 can be attached to the liquid crystal module to be used as a backlight of the liquid crystal module.

On the other hand, it is well known that a liquid crystal module to which the optical anisotropy of liquid crystal is applied is used as a display device for TV and OA equipment. In particular, in the personal computer field of OA equipment, the characteristics of liquid crystal modules such as low drive voltage, low power, and thin type are widely used in accordance with the market demand.

As shown in FIG. 6, the conventional liquid crystal module comprises a liquid crystal panel 11, a backlight 12, a drive circuit (not shown), a module case 13, and a protective plate 24.

Generally, the liquid crystal module receives a power supply voltage, a dot clock signal, a synchronizing signal, and a video signal from the outside, and drives the liquid crystal panel 11 by an internal drive circuit. Since the liquid crystal is not a self-luminous type, the backlight 12 is required. The liquid crystal panel 11, the backlight 12, and the drive circuit are
It is stored in the module case 13. The module case 13 is made by stamping and molding a metal plate material. The module case 3 is partially opened to serve as a display unit. The edge of this opening is referred to as a display frame 16. The image screen of the liquid crystal panel 11 driven by an external signal is observed in the display frame 16 of the module case 13 by the light of the backlight 12.

The protective plate 24 is attached to the entire surface of the display frame 16 of the module case 13 with a bonding material 15 (generally a double-sided tape is used). The protective plate 24 is installed to prevent scratches and reflection on the surface of the liquid crystal panel 11, and is used by making the surface uneven and then subjecting the surface to hardness.

[0009]

Problems to be Solved by the Invention FIGS. 5 (a), 5 (b),
In the conventional backlight shown in (c), the diffusion plate 4
In general, a milky white acrylic plate having high light transmission efficiency is used. By the way, the acrylic plate has a property of being highly hygroscopic and absorbing water at high humidity to expand its volume, and when dried, it is dehydrated again to contract its volume.

Generally, when the water absorption is saturated, the water absorption reaches 2% or more and the elongation reaches about 0.4%. Under normal high humidity environment, the water absorption is about 0.5% and the elongation is 0.1
% To about 0.2%. The diffuser plate 4 has two
The end surface a portion and one longitudinal end surface b portion are in close contact with the face board 5, and in the contact state, the c portion is fixed to the lamp holder 2 with a countersunk screw or the like.

When such a backlight is exposed to a high-humidity environment for a long period of time, the diffusion plate 4 absorbs water and expands in volume, but the a, b, and c parts are fixed, and the horizontal and vertical directions are fixed. Since there is no escape, it is deformed, the function as the diffusing plate 4 is deteriorated, the brightness becomes non-uniform, and it is difficult to attach it to the liquid crystal module, and there is a drawback in that it causes problems in mechanical structure.

On the other hand, the structure of the protective plate 24 and the display frame 16 of the conventional liquid crystal module shown in FIG. 6 is also the same as that of the above-mentioned backlight diffuser plate and face board, and is fixed to the module case 13 of the liquid crystal module. Protection plate 2
No. 4 has a drawback that the central portion is deformed due to an increase in humidity, the protective plate 24 and the liquid crystal panel 11 come into contact with each other, and interference fringes called Newton's rings are generated, which makes the display significantly uneven.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal backlight which does not deform the diffuser plate and the protective plate, has uniform brightness and display, and can be easily attached to the liquid crystal module, and a liquid crystal module using the same. .

According to a first aspect of the invention, at least two fluorescent lamps driven by an inverter are arranged and fixed by a lamp holder, and a reflector and a fluorescent lamp are provided below the fluorescent lamps. A lighting curtain and a diffusion plate are sequentially arranged above, and a face board having a surface height substantially equal to the surface height of the diffusion plate is 3 of the diffusion plates.
In a liquid crystal backlight having a structure arranged adjacent to the periphery of a side, the length of each corresponding side of the diffuser is at least 0..0 between adjacent sides of the diffuser and the faceboard. A gap of 1% is provided, and the diffuser plate is attached to either one of the faceboard and the lamp holder in a structure capable of freely expanding and contracting within the gap.

A second invention is a liquid crystal panel, a liquid crystal backlight of the first invention for illuminating the liquid crystal panel from the back, a module case for accommodating the liquid crystal backlight and the liquid crystal panel, and the module. In a liquid crystal module having a protective plate attached to the display frame of the case,
The protective plate is attached to the display frame with a structure in which at least one end can freely expand and contract.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

1 (a), 1 (b) and 1 (c) are a plan view, a longitudinal sectional view and a lateral sectional view showing the construction of the first embodiment of the first invention.

The first embodiment of the first invention is shown in FIG.
As shown in (a), (b), and (c), the ends a and b of the diffuser plate 4 have gaps 1 and t with respect to the corresponding sides a and b of the faceboard 5. Have For example,
The diffusion plate 4 stretches horizontally and vertically by 20 cm and 15 respectively.
cm is 0.4 mm, 0.
About 3 mm, 0.8 mm, 0.6 mm when saturated with water
If the gaps 1 and t are about 0.4 mm, the diffusion plate 4 is not hindered from expanding and is not deformed.

Further, the mounting portion c of the diffusing plate 4 is mounted by the face board 5 so as to be able to expand and contract in the vertical and horizontal directions, but the gaps 1 and t are provided to prevent the diffusion plate 4 from extending due to water absorption. Instead, it is absorbed in the gaps 1 and t.

2 (a), 2 (b) and 2 (c) are a plan view, a vertical sectional view and a lateral sectional view showing the configuration of the second embodiment of the first invention.

The second embodiment of the second invention is shown in FIG.
As shown in (a), (b) and (c), as in the first embodiment of the first invention of FIG. 1, the diffusion plate 4 and the face board 5 are the same.
The gaps 1 and t are provided between the sides a and b.

Further, the mounting portion c of the diffusion plate 4 is fixed by a countersunk screw, and a gap m is formed inside each c portion.
Is provided so that the diffusion plate 4 can freely expand and contract in the gaps 1 and t with the face board 5, and the extension of the diffusion plate 4 due to water absorption is not hindered and is absorbed in the gaps 1 and t.

3 (a) and 3 (b) are a sectional view showing the structure of the first embodiment of the second invention and a partially enlarged sectional view of its protective plate mounting portion.

The first embodiment of the second invention is shown in FIG.
As shown in (a) and (b), a tap is cut on the outer portion of the display frame 16 of the module case 13, and a mounting hole is provided at a position of the protective plate 14 facing the position. This mounting hole is formed in two steps, large and small, and the size relationship between the mounting hole and the screw 17 is as follows: large hole diameter a> screw head diameter b,
Small hole diameter c> screw thread diameter d, thickness e from display frame to screw head lower surface e> small diameter thickness f. (A-b) and (c
The value of -d) is determined depending on the length of the protective plate 14, the humidity used by the liquid crystal module, and environmental changes in the humidity. Generally, the gap is 0.8 to 2.0 mm for a length of 30 cm.
Is decided. The value of (ef) is generally 0.05 to 0.3 mm in consideration of the thickness of the protective plate 14 and the usage conditions.
Is decided.

After the liquid crystal panel 11 and the backlight 12 are housed in the module case 13, the protection panel 14 is placed right above the display frame 16 of the module case 13 and attached with the set screw 17. The protection plate 14 attached in this way has a structure capable of expanding and contracting in the left-right direction by (ab) mm.

Further, one side of the protective plate 14 is fixed with a bonding material,
It is easy to see that the structure has a structure in which the other end can be expanded and contracted even if it is attached with the set screw 17. In this case, the dimensional relationship must be set appropriately so that the same amount can be expanded and contracted.

FIG. 4 is a sectional view showing the structure of the second embodiment of the second invention.

In the second embodiment of the second invention, as shown in FIG. 4, a notch is provided on the upper surface of the end surface of the protective plate 14. The relationship between the dimension h of the display portion of the protective plate 14 and the dimension g of the display frame 16 of the module case 13 is g> h. The value of (gh) is 0.8 to 2.0 mm as described above. A spacer 18 is provided at the edge of the liquid crystal panel 11 so as to maintain the dimensions of the protective plate 14 and the liquid crystal panel 11.

This structure is also a structure in which the protective plate 14 can be expanded and contracted, and has an advantage that it can be applied without using a set screw or a tap.

[0029]

As described above, according to the present invention, a gap is provided between the diffuser plate of the liquid crystal backlight and the face board, the protective plate of the liquid crystal module and the adjacent sides of the display frame, and the diffuser plate and the diffuser plate. By installing the protective plate so that it can expand and contract freely, the flatness may be impaired due to the structure in which the liquid crystal module can expand and contract freely in the gap even if the diffusion plate and the protective plate absorb water and expand under high humidity environment. There is an effect that a uniform display can be obtained.

There is also an effect that the liquid crystal backlight can be easily attached to the liquid crystal module.

[Brief description of drawings]

FIG. 1 is a plan view, a vertical sectional view, and a horizontal sectional view showing a configuration of a first embodiment of the first invention.

FIG. 2 is a plan view, a vertical sectional view and a lateral sectional view showing the configuration of a second embodiment of the first invention.

FIG. 3 is a cross-sectional view showing a configuration of a first embodiment of the second invention and a partially enlarged cross-sectional view of a protective plate mounting portion thereof.

FIG. 4 is a cross-sectional view showing the configuration of the second embodiment of the second invention.

5A and 5B are a plan view, a vertical cross-sectional view, and a horizontal cross-sectional view showing the configuration of an example of a conventional liquid crystal backlight.

FIG. 6 is a cross-sectional view showing a configuration of an example of a conventional liquid crystal module.

[Explanation of symbols]

 1 Fluorescent Lamp 2 Lamp Holder 3 Lighting Curtain 4 Diffuser 5 Face Board 6 Reflector 7 Inverter 8 Inverter Case 11 Liquid Crystal Panel 12 Backlight 13 Module Case 14, 24 Protective Plate 15 Bonding Material 16 Display Frame 17 Set Screw 18 Spacer

Claims (2)

[Claims] 1. At least two fluorescent lamps driven by an inverter are arranged and fixed by a lamp holder, and a reflector is arranged below the fluorescent lamps, and a lighting curtain and a diffusion plate are arranged above the fluorescent lamps in order. In a liquid crystal backlight having a structure in which a face board having a surface height substantially equal to the surface height of the diffuser plate is arranged adjacent to the periphery of three sides of the diffuser plate, the diffuser plate and the face board are adjacent to each other. And a faceboard having a structure in which a gap of at least 0.1% of the length of each corresponding side of the diffusion plate is provided between the respective sides, and the diffusion plate can freely expand and contract within the gap. A liquid crystal backlight mounted on either one of the lamp holders. 2. A liquid crystal panel, a liquid crystal backlight according to claim 1, which illuminates the liquid crystal panel from the back, a module case for housing the liquid crystal backlight and the liquid crystal panel, and a display frame of the module case. A liquid crystal module having a protective plate attached to the display frame, wherein the protective plate is attached to the display frame in such a manner that at least one end thereof can freely expand and contract.