KR100949497B1 - The back light for liquid crystal display device - Google Patents

Abstract

 The present invention relates to a direct backlight of a liquid crystal display device capable of improving the quality of an image by preventing scratches of a diffusion plate from an external impact, comprising: at least one light source for emitting light; A frame accommodating the light source; A diffusion plate formed on an upper portion of the frame to scatter and diffuse light emitted from the light source; It is configured to include at least one wire formed between the frame and the diffusion plate.

LCD, Diffusion Plate, Scratch, Wire, Direct Backlight

Description

Back light for liquid crystal display device

1 is a perspective view of a direct backlight of a conventional liquid crystal display

2 is a perspective view of a direct backlight of the liquid crystal display according to the present invention.

3A to 3B are plan views illustrating a diffusion plate and a support form of wires for the diffusion plate in the direct backlight of the liquid crystal display according to the present invention.

* Explanation of symbols on the main parts of the drawings

  21: light source 22: reflector

  23: frame 24: wire

  25a: diffuser plate 25b: prism sheet

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct backlight of a liquid crystal display device, and more particularly to a direct backlight of a liquid crystal display device capable of improving image quality by preventing scratches of a diffusion plate from external impact.

In recent years, research on flat panel display devices has been actively conducted. Among them, liquid crystal display devices (LCDs), field emission display devices (FEDs), electro-luminescence display devices (ELDs), and PDPs are attracting attention. (Plasma Display Pannels).

Among them, LCD is the most widely used as a substitute for CRT (Cathode Ray Tube) for the use of mobile image display device because of the excellent image quality, light weight, thinness, and low power consumption, and mobile type such as monitor of notebook computer. In addition, it is being developed in various ways, such as a television for receiving and displaying broadcast signals, and a monitor of a computer.

As described above, although various technical advances have been made in order for the liquid crystal display device to serve as a screen display device in various fields, the task of improving the image quality as the screen display device has many advantages and disadvantages.

Therefore, in order to use a liquid crystal display device in various parts as a general screen display device, the key to development is how much high definition images such as high definition, high brightness, and large area can be realized while maintaining the characteristics of light weight, thinness, and low power consumption. It can be said that it is hanging.

Such a liquid crystal display device may be classified into a liquid crystal display panel displaying an image and a driving unit for applying a driving signal to the liquid crystal display panel, wherein the liquid crystal display panel has a space and is bonded to the first and second substrates. And a liquid crystal layer injected between the first and second substrates.

The first substrate (TFT array substrate) may include a plurality of gate lines arranged in one direction at a predetermined interval, a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines, A plurality of thin film transistors which are switched by a plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing gate lines and data lines and signals of the gate lines to transfer signals of the data lines to the pixel electrodes. Is formed.

The second substrate (color filter substrate) includes a black matrix layer for blocking light in portions other than the pixel region, R, G, and B color filter layers for expressing color colors, and a common electrode for implementing an image. Is formed.

The first and second substrates have a predetermined space by spacers and are bonded by a sealant to form a liquid crystal between the two substrates.

Since the liquid crystal display itself is non-luminescent, a separate external light source for irradiating light is required.

 In particular, in the case of a transmissive liquid crystal display, a separate dimming device that emits light and guides the back of the liquid crystal display panel, that is, a back light device is necessary.

The back light includes an edge type method and a direct type method.

In the direct type, a light emitting lamp is disposed on a flat surface. Since the shape of the light emitting lamp appears on the liquid crystal panel, the gap between the light emitting lamp and the liquid crystal display panel should be maintained, and light scattering means is disposed for the uniform distribution of light. There is a limit to thinning because it must be.

In addition, as the liquid crystal display panel becomes larger, the area of the light exit surface of the backlight also increases. When the direct backlight is enlarged, the light exit surface is not flat unless the light scattering means secures sufficient thickness. For this reason, the thickness of the light scattering means must be sufficiently secured.

On the other hand, the edge type is to install a light emitting lamp on the outside and to distribute the light to the entire surface using a light guide plate, the light emitting lamp is installed on the side, there is a problem that the brightness is low because the light must pass through the light guide plate. In addition, high optical design and processing techniques for the light guide plate are required for uniform distribution of luminance.

Since the direct type and edge type have their disadvantages, the direct type type backlight is mainly used in the liquid crystal display where brightness is more important than the screen thickness. In an important liquid crystal display device, an edge type backlight is mainly used.

Currently, as part of implementing high-brightness backlights, research and development on direct type backlights have continued, such as disposing several lamps on the lower side of a display screen or by arranging one lamp.

Hereinafter, a direct backlight of a conventional liquid crystal display device will be described with reference to the accompanying drawings.

1 is a perspective view of a direct backlight of a conventional liquid crystal display.

Direct backlight of the conventional liquid crystal display device, as shown in Fig. 1, at least one light emitting lamp 1 for emitting light, and diffused to scatter and diffuse the light emitted from the light emitting lamp (1) A plate 5a, a prism sheet 5b which receives and scatters the light scattered and diffused by the diffusion plate 5a and provides the light to the display unit of a liquid crystal display panel (not shown), and the light emitting lamp 1 It consists of the frame 3 which fixes and supports.

Here, the diffusion plate 5a and the prism sheet 5b are for preventing the shape of the light emitting lamp 1 from appearing on the display surface of the liquid crystal display panel and providing light having a uniform brightness distribution as a whole. In order to enhance the effect, a plurality of light emitting lamps 1 and the liquid crystal display panel may be provided.

In addition, a reflector 7 is disposed on the inner surface of the frame 3 so that the light emitted from the light emitting lamp 1 can be concentrated to the display unit side of the liquid crystal display panel, thereby maximizing light utilization efficiency.

The light emitting lamp 1 generally uses a Cold Cathode Fluorescent Lamp (CCFL), and electrodes are disposed at both ends of a tube to emit light when power is applied to the electrodes.

Here, since there is considerable space between the light emitting lamp 1 and the diffuser plate 5a, the diffuser plate 5a is convex in the center in the direction of gravity due to its own mass or the heat generated by the light emitting lamp 1. Drooping phenomenon occurs.

In order to prevent this phenomenon, a plurality of supports 10 are provided between the diffusion plate 5a and the reflective sheet 7 to prevent sagging of the diffusion plate 5a.

 Here, the support 10 is made of a hard material such as polycarbonate (polycarbonate) to prevent sagging of the diffusion plate (5a).

In addition, since the support 10 may appear on the display surface of the liquid crystal display panel, the support 10 is sharply formed in contact with the diffusion plate 5a to reduce the contact surface to a minimum.

However, when an external shock or vibration is applied to the direct backlight of the conventional liquid crystal display configured as described above, foreign substances or scratches are generated at the contact surface between the diffusion plate and the support.

The foreign matter and scratches eventually affect the display surface of the liquid crystal display panel, which causes a bad image.

And, since the end of the support is formed sharply, when the external impact is severe, the end is broken or deformed so that it cannot perform its proper function.

That is, the deflection of the diffusion plate may not be prevented properly. Accordingly, the diffusion plate may not properly scatter and diffuse the light transmitted from the light emitting lamp, resulting in a problem of deterioration of image quality of the liquid crystal display panel. Done.

On the other hand, in order to solve this problem, the support can be made of a soft material such as rubber, but in this case it will result in the lack of strength can not support the diffusion plate properly.

The present invention has been made to solve the above problems, by forming a high-tension wire between the diffusion plate and the light source (light emitting lamp), to protect the diffusion plate from external impact to improve the image quality It is an object of the present invention to provide a direct backlight of a liquid crystal display.

Direct type backlight of the liquid crystal display device according to the present invention for achieving the above object comprises at least one light source for emitting light; A frame accommodating the light source; A diffusion plate formed on an upper portion of the frame to scatter and diffuse light emitted from the light source; Characterized in that it comprises at least one wire formed between the frame and the diffusion plate.

The wire is characterized by using a low thermal expansion coefficient and a high strength material.

The wire is characterized in that it is connected with a tension between the opposite edge of the frame.

The wire is formed along an imaginary line dividing the entire area of the diffusion plate evenly.

A prism sheet for collecting and scattering light scattered and diffused from the diffusion plate may be further formed on the diffusion plate.

The wire is characterized in that made of tungsten.

Hereinafter, a direct backlight of a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a perspective view of a direct backlight of the liquid crystal display according to the present invention.

Direct type backlight of the liquid crystal display according to the present invention, as shown in Figure 2, at least one light source 21 for emitting light; A frame (23) for receiving the light source (21); A diffusion plate 25a formed on the frame 23 to scatter and diffuse light emitted from the light source 21; A prism sheet 25b which receives the scattered and diffused light from the diffusion plate 25a and condenses and emits the light; It consists of two wires 24 formed between the frame 23 and the diffusion plate 25a.

In addition, a reflector 22 is disposed on the inner surface of the frame 23 so that the light generated from the light source 21 can be irradiated to the display unit side of the liquid crystal display panel so as to maximize light utilization efficiency.

Here, the diffusion plate 25a and the prism sheet 25b prevent the shape of the light source 21 from appearing on the display surface of the liquid crystal display panel (not shown) and provide light having a uniform brightness distribution as a whole. In order to improve the light scattering effect, a plurality of light sources 21 and the liquid crystal display panel may be configured.

In general, the light source 21 may be a cold cathode tube (CCFL: Cold Cathode Fluorescense Lamp), such as a straight tube, a U tube, a W tube, etc., but the straight type is most preferable in terms of high brightness and high uniformity.

The light source 21 is supported and fixed by a lamp supporter (not shown) formed inside the frame 23 that accommodates the light source 21.

Here, the lamp supporter is located at both ends of the inside of the frame 23, and has a plurality of lamp receiving grooves (not shown) facing each other at appropriate intervals.

A wire 24 having high tension and strength is fixedly connected between opposite edges of the frame 23, and scatters and diffuses light emitted from the light source 21 on the wire 24 formed as described above. Diffusion plate 25a is placed.

Here, the diffusion plate 25a serves to diffuse the light evenly using particles having good diffusion efficiency, and the diffusion plate 25a generally uses a PET film as a base film and binders on one or both surfaces thereof. It is obtained by coating a composition comprising a resin and particles.

The wire 24 prevents convex sag in the direction of gravity due to its own mass of the diffusion plate 25a or heat generated by the light source 21, and to the contact surface of the diffusion plate 25a during external impact. This is to prevent foreign substances or scratches from occurring.

Accordingly, the wire 24 has a low coefficient of thermal expansion in order to maintain high tension even at a high temperature, and has a strength sufficient to bear the mass of various optical sheets such as the diffusion plate 25a and the prism sheet 25b. It is desirable to use a high material.

As a material of the wire 24 having the above characteristics, for example, a material such as high tension tungsten may be used.

Such a wire 24 should be formed at an optimal position to divide the area of the diffusion plate 25a evenly, so that the center of gravity of the diffusion plate 25a is not biased to either side.

3A to 3B are cross-sectional views illustrating a diffusion plate and a support form of wires for the diffusion plate in the direct backlight of the liquid crystal display according to the present invention.                     

As shown in FIG. 3A, when the area of the diffusion plate 25a is divided into three equal parts in the long side direction of the diffusion plate 25a, two dotted lines 31a and 31b that divide the diffusion plate 25a into three equal parts. Follow the two wires 24 to be installed.

As shown in FIG. 3B, the two wires 24 are connected so as to be perpendicular to each other so that the area of the diffusion plate 25a is divided into two equal parts in the long side direction of the diffuser plate 25a and divided into two equal parts in the short side direction. In this case, one wire 24 is provided along one dotted line 41a dividing the area of the diffusion plate 25a in two long directions, and the area of the diffusion plate 25a is divided into two equal parts in a short side direction. One wire 24 is installed along one dotted line 41b.

Here, when the area where the wire 24 is in contact with the diffusion plate 25a becomes large, the area of the display portion of the liquid crystal display panel may be darkened by the contact surface, so that the width of the wire 24 is increased. It is desirable to make it as small as possible.

As can be seen from such a configuration, since the conventional support (10 in Fig. 1) supports the diffusion plate (5a in Fig. 1) in the vertical direction, a lot of pressure is applied to the contact surface with the diffusion plate (5a in Fig. 1). In the present invention, since the wire 24 is used to uniformly support a large area in the horizontal direction of the diffusion plate 25a, the pressure applied to the contact surface is significantly reduced compared to the conventional support.

As described above, the direct type backlight of the liquid crystal display according to the present invention can prevent scratches of the diffusion plate 25a due to external impact by replacing the conventional support (10 in FIG. 1) with the wire 24. Accordingly, the image quality of the liquid crystal display panel can be improved.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

As described above, the direct backlight of the liquid crystal display according to the present invention has the following effects.

First, since the direct backlight of the conventional liquid crystal display device supports a diffuser plate in a vertical direction by using a supporter, a lot of pressure is applied to the contact surface with the diffuser plate, but the present invention uniformly supports a large area in the horizontal direction. As a result, the pressure applied to the contact surface is remarkably reduced in comparison with the conventional support, and it is possible to prevent scratches of the diffusion plate due to external impact.

Second, since the direct backlight of the conventional liquid crystal display device uses a sharp support to prevent sagging of the diffusion plate, the shape of the support appears on the display of the liquid crystal display panel, thereby degrading image quality. As described above, the direct type backlight of the liquid crystal display device of the present invention uniformly supports all areas of the diffusion plate by using wires, so that less pressure is applied to the contact with the diffusion plate. The shape of the wire does not appear so that the quality of the image can be improved.

Claims (6)

At least one light source for emitting light; A frame accommodating the light source; A diffusion plate formed on an upper portion of the frame to scatter and diffuse light emitted from the light source; A prism sheet formed on an upper portion of the diffuser plate to receive and scatter light scattered and diffused from the diffuser plate; At least one wire formed between the frame and the diffuser plate; The wires are connected in tension between opposing edges of the frame; The wire is a direct type backlight of the liquid crystal display device, characterized in that the low thermal expansion coefficient and made of high strength. delete delete The method of claim 1, And the wire is formed along an imaginary line dividing the entire area of the diffusion plate evenly. delete delete

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