KR101361886B1 - Optical plate, backlight assembly having the same, and the liquid crystal display device - Google Patents

Abstract

Disclosed are an optical plate, a backlight assembly and a liquid crystal display device having the same.

An optical plate of the present invention comprises a first prism plate having a plurality of first prism patterns along a first direction, and a plurality of second along a second direction disposed on the first prism plate and perpendicular to the first direction. And a second prism plate having a prism pattern. The first prism plate has a radius of curvature at least greater than the second prism plate.

Accordingly, the present invention allows the light to be diffused by the first prism plate and the light to be collected by the second prism plate, thereby not only simplifying the optical structure but also reducing the cost as fewer optical members are used. have.

In addition, the present invention can improve the light efficiency by increasing the brightness of the light by adjusting the angle and the radius of curvature of each of the first prism pattern of the first prism plate and the second prism pattern of the second prism plate.

Backlight assembly, optical plate, prism plate, radius of curvature

Description

Optical plate, backlight assembly having the same, and the liquid crystal display device}

1 is a schematic illustration of a conventional direct backlight assembly;

2 is a schematic illustration of a direct backlight assembly according to the present invention;

3 is a cross-sectional view taken along the line AA ′ of the first prism plate of FIG. 2.

4 is a view showing the shape of the first prism pattern in the first prism plate of FIG.

FIG. 5 is a cross-sectional view of the second prism plate of FIG. 2 taken along line BB ′. FIG.

FIG. 6 illustrates the shape of a second prism pattern in the second prism plate of FIG. 5. FIG.

FIG. 7 is a view showing a propagation path of light in the first prism plate of FIG. 2. FIG.

FIG. 8 is a view showing a propagation path of light in the second prism plate of FIG. 2. FIG.

9 shows a spacer member disposed between the first and second prism plates.

10 shows another view of the spacer member disposed between the first and second prism plates.

11A and 11B are views of a luminance image according to the prior art and the present invention.

<Explanation of symbols for the main parts of the drawings>

1: bottom cover 3: lamp

5, 7: Prism plate 11, 21: base plate

13, 23: prism pattern 31: ball spacer

41: outermost prism pattern

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight assembly, and more particularly, to an optical plate capable of simplifying a structure, improving light efficiency, and reducing costs, and a backlight assembly and a liquid crystal display device having the same.

As the information society develops, the demand for display devices is increasing in various forms. In response to this, various flat panel display devices including liquid crystal display (LCD), plasma display panel (PDP) and electro luminescent display (ELD) have been studied. Is already widely used as a display device.

Among them, the liquid crystal display device is presently excellent in image quality and has advantages such as light weight, thinness, low power consumption, and the like, thereby rapidly replacing the CRT. The liquid crystal display is being developed in various ways such as a monitor of a notebook, a display panel of a television.

The liquid crystal display includes a liquid crystal panel in which a plurality of pixels are arranged in a matrix form, and a backlight assembly disposed on a rear surface of the liquid crystal panel to irradiate light to the liquid crystal panel.

The backlight assembly is divided into an edge type in which a light source is provided at a side, and a direct type in which a plurality of light sources are provided at predetermined intervals.

1 is a view schematically showing a conventional direct type backlight assembly.

As shown in FIG. 1, a plurality of lamps 115 generating light in the bottom cover 110 is disposed. An optical sheet 150 for controlling light is disposed on the lamp 115. The optical sheet 150 includes a diffusion sheet 130 for diffusing light and a prism sheet 140 disposed on the diffusion sheet 130 to condense the light.

Since the optical sheet 150 is made of a thin sheet, it is not supported and sags downward. A diffusion plate 120 is disposed between the lamp 115 and the optical sheet 150 to prevent sagging of the optical sheet 150 while supporting diffusion of light. The diffusion plate 120 may be formed thick to serve as a support. Therefore, the optical sheet 150 may be disposed in parallel by the diffusion plate 120 without sagging in the downward direction.

However, since the conventional direct backlight assembly requires a plurality of sheets such as the diffusion plate 120, the diffusion sheet 130, and the prism sheet 140 to control the light, the structure is complicated.

In addition, the conventional direct type backlight assembly is provided with a diffusion plate 120 and a diffusion sheet 130 instead of a single optical member to diffuse the light, the cost is increased as the same function is used repeatedly.

In addition, the conventional direct backlight assembly has to optimize the structure of the diffusion plate 120 and the diffusion sheet 130 to diffuse light. However, there is a problem in that it is not easy to obtain the optimal light efficiency by optimizing the diffusion plate 120 and the diffusion sheet 130.

In addition, the conventional direct type backlight assembly has a problem in that light loss occurs in each sheet as a plurality of sheets are provided, thereby reducing light efficiency.

An object of the present invention is to provide an optical plate, a backlight assembly and a liquid crystal display device having the same, which can simplify the structure.

Another object of the present invention is to provide an optical plate, a backlight assembly having the same, and a liquid crystal display device which can reduce cost.

Still another object of the present invention is to provide an optical plate capable of improving light efficiency, a backlight assembly having the same, and a liquid crystal display device.

According to a first embodiment of the present invention for achieving the above object, an optical plate comprises: a first prism plate having a plurality of first prism patterns along a first direction; And a second prism plate disposed on the first prism plate and having a plurality of second prism patterns in a second direction perpendicular to the first direction. The first prism plate has a radius of curvature at least greater than the second prism plate.

According to a second embodiment of the present invention, a backlight assembly includes a bottom cover; A plurality of light sources disposed on the bottom cover; And an optical plate disposed on the plurality of light sources. The optical plate may include a first prism plate having a plurality of first prism patterns along a first direction; And a second prism plate disposed on the first prism plate and having a plurality of second prism patterns along a second direction perpendicular to the first direction, wherein the first prism plate is the second prism plate. Have a radius of curvature at least greater.

According to a third embodiment of the present invention, a liquid crystal display device includes: a backlight assembly according to the second embodiment; A liquid crystal panel disposed on the backlight assembly; And a top case disposed on the liquid crystal panel and fastened to the bottom cover of the backlight assembly.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic view illustrating a direct backlight assembly according to the present invention, FIG. 3 is a cross-sectional view taken along line AA ′ of the first prism plate of FIG. 2, and FIG. 4 is a first prism plate of FIG. 3. 5 is a cross-sectional view of the second prism plate of FIG. 2 taken along the line BB ′, and FIG. 6 is a cross-sectional view of the second prism pattern of the second prism plate of FIG. It is a figure which shows a shape.

2 to 6, a plurality of lamps 3 for generating light in the bottom cover 1 is disposed. The lamp 3 may be a cold cathode fluorescent lamp or an external electrode fluorescent lamp. Instead of the lamp 3, a plurality of light emitting diodes may be mounted in a package having a longitudinal direction. A reflector may be attached to the inner surface of the bottom cover 1 to reflect light. The lamp 3 is disposed spaced apart from the bottom cover 1 by a predetermined interval. To this end, a supporting member may be disposed between the lamp 3 and the bottom cover 1 so that the lamp 3 is spaced apart from the bottom cover 1 by a predetermined distance.

A first prism plate 5 is arranged on the lamp 3. A plurality of first prism patterns 13 are formed in the first prism plate 5 along the length direction of the lamp 3.

A second prism plate 7 is arranged on the second prism plate 7. A plurality of second prism patterns 23 are formed in the second prism plate 7 in a direction perpendicular to the length direction of the lamp 3.

Therefore, the first prism pattern 13 and the second prism pattern 23 cross each other perpendicularly. This is to more efficiently control the light passing through the first and second prism plates 5, 7. That is, the light passing through the first prism pattern 13 of the first prism plate 5 may be easily controlled by the second prism pattern 23 disposed perpendicularly to the first prism pattern 13. Can be.

The present invention is not limited thereto, and the first and second prism patterns 13 and 23 may be formed in the same direction without departing from the spirit of the present invention.

Shapes of the first and second prism plates 5 and 7 may be determined by thicknesses t1 and t2, peak angles θ1 and θ2, radiuses of curvature R1 and R2 and pitches P1 and P2. . This will be described in detail below.

As shown in FIGS. 3 and 4, the first prism plate 5 includes a first base plate 11 and the first prism pattern 13 formed on the first base plate 11. do.

The height of the first base plate 11 is defined by the thickness t1. The first prism pattern 13 may have a corner region 15 thereon, and the corner region 15 may be formed with a mountain having a round shape. The angle θ1 and the round shape of the peak may be determined by the radius of curvature R1.

As shown in FIG. 4, the radius of curvature R1 may be defined by the radius of a circle formed to contact two surfaces of the mountain.

The width from the first adjacent point to the second adjacent point of the adjacent first prism pattern 13 may be defined as the pitch P1.

The first base plate 11 and the first prism pattern 13 may be integrally formed or separately.

The first base plate 11 and the first prism pattern 13 may be integrally formed by an injection molding method using a stamp or a mold. Alternatively, the first base plate 11 and the first prism pattern 13 may be integrally formed by a V cutting method. The V-cutting method scrapes a surface to form the first prism pattern 13 integrally formed on the base plate. As such, when the first base plate 11 and the first prism pattern 13 are integrally formed, the first base plate 11 and the first prism pattern 13 may be polymethyl methacrylate (PMMA). : Poly methyl methacrylate (PC) material, polycarbonate (PC: poly carbonate) material, it may be made of any one material of acrylic (acryl) material.

The first prism pattern 13 may be formed in a sheet form and attached to the first base plate 11 by laminating. As such, when the first base plate 11 and the first prism pattern 13 are formed separately, the first base plate 11 may be made of polymethyl methacrylate (PMMA) material, poly The material may be formed of any one of a polycarbonate (PC) material and an acrylic material, and the first prism pattern 13 may be formed of an acrylic material or a polyester material. In this case, the first prism pattern 13 is preferably made of a material having a refractive index smaller than that of the first base plate 11 to facilitate diffusion.

The pitch P1 of each of the first prism patterns 13 may be the same or different. The pitch P1 may have a range of 0.05 mm to 0.3 mm. The thickness t1 of the first base plate 11 may have a range of 0.5 mm to 3 mm.

The angle θ1 of the peak of the first prism pattern 13 may range from 90 degrees to 160 degrees. At this time, the radius of curvature (R1) may have a range of 0.2 to 0.5 of the pitch (P1).

As shown in FIGS. 5 and 6, the second prism plate 7 includes a second base plate 21 and the second prism pattern 23 formed on the second base plate 21. do.

The height of the second base plate 21 is defined by the thickness t2. The second prism pattern 23 may have a top region 25 at an upper portion thereof, and the top region 25 may have a mountain having a round shape. The angle θ2 and the round shape of the peak may be determined by the radius of curvature R2.

As shown in FIG. 6, the radius of curvature R2 may be defined by the radius of a circle formed to contact two sides of the mountain.

The width from the first adjacent point to the second adjacent point of the adjacent second prism pattern 23 may be defined as the pitch P2.

The second base plate 21 and the second prism pattern 23 may be integrally formed or separately.

The second base plate 21 and the second prism pattern 23 may be integrally formed by an injection molding method using a stamp or a mold. Alternatively, the second base plate 21 and the first prism pattern 13 may be integrally formed by a V cutting method. The V-cutting method scrapes a surface to form the second prism pattern 23 integrally formed on the base plate. As such, when the second base plate 21 and the second prism pattern 23 are integrally formed, the second base plate 21 and the second prism pattern 23 may be polymethyl methacrylate (PMMA). : Poly methyl methacrylate (PC) material, polycarbonate (PC: poly carbonate) material, it may be made of any one material of acrylic (acryl) material.

The second prism pattern 23 may be formed in a sheet form and attached to the second base plate 21 by a laminating method. As such, when the second base plate 21 and the second prism pattern 23 are formed separately, the second base plate 21 may be made of polymethyl methacrylate (PMMA) material, poly The material may be made of any one of a polycarbonate (PC) material and an acrylic material, and the second prism pattern 23 may be made of an acrylic material or a polyester material. In this case, the second prism pattern 23 is preferably made of a material having a refractive index smaller than that of the second base plate 21 to facilitate diffusion.

The pitch P2 of each of the second prism patterns 23 may be the same or different. The pitch P2 may have a range of 0.05 mm to 0.3 mm. The thickness t2 of the second base plate 21 may range from 0.5 mm to 3 mm.

The angle θ2 of the peak of the second prism pattern 23 may range from 80 degrees to 140 degrees. At this time, the radius of curvature (R2) may have a range of 0.1 to 0.3 of the pitch (P2).

In summary, the first and second prism patterns may have the same pitches P1 and P2 or may have different pitches P1 and P2. In this case, the pitches P1 and P2 may have a range of 0.05 mm to 0.3 mm.

The heights of the first and second base plates 11 and 21 may range from 0.5 mm to 3 mm.

The angle θ1 of the first prism pattern 13 may range from 90 degrees to 160 degrees, and the angle θ2 of the second prism pattern 23 may range from 80 degrees to 140 degrees.

The radius of curvature of the first prism pattern 13 may range from 0.2 to 0.5 of the pitch of the first prism pattern 13. The radius of curvature of the second prism pattern 23 may have a range of 0.1 to 0.3 of the pitch of the second prism pattern 23.

As such, the angle of the peak θ1 and the radius of curvature R1 of the first prism plate 5 may be greater than the angle of the peak θ2 and the radius of curvature R2 of the second prism plate 7. have. Therefore, the first prism plate 5 can diffuse the light more easily, and the second prism plate 7 can focus the light more easily.

As shown in FIG. 7, in the first prism plate 5, light tends to be diffused rather than condensed because the angle θ1 and the radius of curvature R1 of the peak are relatively large. Therefore, light can be spread more uniformly by the first prism plate 5.

As shown in FIG. 8, in the second prism plate 7, light tends to be focused rather than diffused because the angle θ2 and the radius of curvature R2 of the peaks are relatively small. Therefore, the brightness of the light can be further increased by the second prism plate 7.

Therefore, the present invention can improve the uniformity of light and the brightness of light by providing the first and second prism plates 5, 7.

In addition, the present invention simply includes the first and second prism plates 5, 7, so that the structure can be simplified and the cost can be reduced as the optical member is used less than in the prior art.

A first prism pattern 13 is formed on the first prism plate 5, and a second prism plate 7 is disposed on the first prism plate 5. In this case, the first prism pattern 13 of the first prism plate 5 comes into contact with the second prism plate 7. Therefore, the first prism pattern 13 of the first prism plate 5 may be damaged by the contact with the second prism plate 7, thereby reducing the light efficiency.

Therefore, a spacer member may be formed to prevent the first prism pattern 13 of the first prism plate 5 from contacting the second prism plate 7.

9, the spacer may be formed between the first prism patterns 13 of the first prism plate 5, that is, in the valley region 33. The spacer may be a ball spacer 31. The ball spacer 31 may be formed integrally with the first prism plate or may be formed separately. When the ball spacer 31 is integrally formed with the first prism plate 5, the ball spacer 31 is formed in the valley region 33 between the first prism patterns 13 in the first base plate. Protruding from (11) can be formed. When the ball spacer 31 is formed separately from the first prism plate 5, the ball spacer 31 is prepared in advance and dispersed on the first prism plate 5, thereby providing the first prism plate. (5) can be formed.

As shown in FIG. 10, the outermost prism pattern 41 positioned in the outermost region of the first prism patterns 13 formed on the first prism plate 5 is relatively compared to other prism patterns. It may be formed to protrude in the upper direction. Accordingly, the second prism plate 7 is seated on the prism pattern located in the outermost region of the first prism plate 5, and the outermost prism pattern 41 located in the outermost region is compared with other prism patterns. Since the second prism plate 7 is protruded in a relatively upward direction, the second prism plate 7 does not come into contact with the first prism pattern 13 of the first prism plate 5 to damage the first prism pattern 13. It can prevent.

On the other hand, when only the prism pattern 41 formed in the outermost region is formed, the second prism plate 7 in the center region sags downward to contact the first prism plate 7, thereby causing friction. Can be.

In order to solve this problem, a prism pattern protruding relative to other prism patterns may be randomly formed in the entire region of the first prism plate 5. Accordingly, since the second prism plate 7 is supported by the protruding prism pattern randomly formed on the first prism plate 5, the second prism plate 7 does not come into contact with another prism pattern.

In addition, the number of randomly formed protrusion prism patterns may be adjusted according to the size of the backlight.

11A and 11B are diagrams of a luminance image according to the related art and the present invention. FIG. 11A is a conventional luminance image and FIG. 11B is a luminance image of the present invention.

Conventionally, a diffusion plate, a diffusion sheet, and a prism sheet are provided. In the present invention, first and second prism plates 5 and 7 are provided.

As shown in FIGS. 11A and 11B, the maximum luminance of the present invention is 6763 and the conventional maximum luminance is 5165, indicating that the present invention increases the luminance by 20% or more.

In addition, it can be seen that the weber, which is a numerical value representing uniformity, is further improved in the present invention compared with the related art. Weber indicates that the smaller the value, the better the uniformity. Therefore, while the conventional webber is 3%, the webber of the present invention is 2.41%, and it can be seen that the present invention further improves uniformity as compared to the conventional webber.

The backlight assembly configured as described above may be applied to a liquid crystal display device. The liquid crystal display includes a backlight assembly configured as described above, a liquid crystal panel disposed on the backlight assembly to display an image by transmitting / blocking light provided from the backlight assembly, and the liquid crystal panel to protect and fix the liquid crystal panel. It is disposed on the front of the panel includes a top case fastened to the bottom cover (1) of the backlight assembly.

As described above, according to the present invention, the first and second prism plates each having a prism pattern, the light is diffused by the first prism plate and the light is focused by the second prism plate, In addition, the optical structure is not only simplified, but the cost can be reduced as fewer optical members are used.

According to the present invention, by adjusting the angle and the radius of curvature of each of the first prism pattern of the first prism plate and the second prism pattern of the second prism plate, it is possible to increase the brightness of the light to improve the light efficiency.

According to the present invention, by providing a spacer member between the first and second prism plate to prevent the prism pattern of the first prism plate from contacting the second prism plate by the spacer member, damage to the prism pattern can be prevented. have.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims (42)

A first prism plate having a plurality of first prism patterns; And A second prism plate disposed on the first prism plate, the second prism plate having a plurality of second prism patterns intersecting the plurality of first prism patterns, The radius of curvature of the first prism pattern is greater than the radius of curvature of the second prism pattern, And the angle of the peaks of the first prism pattern is greater than the angle of the peaks of the second prism pattern. The optical plate of claim 1, wherein each of the first and second prism patterns has a pitch of 0.05 mm to 0.3 mm. The method of claim 1, wherein at least one of the first and second prism plates is made of any one of a poly methyl methacrylate material, a polycarbonate material, and an acryl material. An optical plate, characterized in that. The optical plate of claim 1, wherein a radius of curvature of the first prism pattern is in a range of 0.2 to 0.5 of a pitch of the first prism pattern. The optical plate of claim 1, wherein a radius of curvature of the second prism pattern is in a range of 0.1 to 0.3 of a pitch of the second prism pattern. The optical plate of claim 1, wherein an angle of a peak of the first prism pattern is in a range of 90 degrees to 160 degrees. The optical plate of claim 1, wherein an angle of a peak of the second prism pattern is in a range of 80 degrees to 140 degrees. The optical plate of claim 1, further comprising a spacer member disposed between the first and second prism plates to space between the first and second prism plates. The optical plate of claim 8, wherein the spacer is a ball spacer. The optical plate of claim 9, wherein the ball spacer and the first prism plate are integrally formed. The optical plate of claim 10, wherein the ball spacer protrudes from the first prism plate. The optical plate of claim 9, wherein the ball spacer and the first prism plate are formed separately. The optical plate of claim 8, wherein the spacer is a prism pattern randomly formed on the first prism plate. The optical plate of claim 13, wherein the randomly formed prism pattern is formed to protrude upwardly relative to other prism patterns. Bottom cover; A plurality of light sources disposed on the bottom cover; And An optical plate disposed on the plurality of light sources, The optical plate, A first prism plate having a plurality of first prism patterns; And A second prism plate disposed on the first prism plate, the second prism plate having a plurality of second prism patterns intersecting the plurality of first prism patterns, The radius of curvature of the first prism pattern is greater than the radius of curvature of the second prism pattern, And the angle of the peaks of the first prism pattern is greater than the angle of the peaks of the second prism pattern. The backlight assembly of claim 15, wherein the light source is any one of a cold cathode fluorescent lamp, an external electrode fluorescent lamp, and a light emitting diode. The backlight assembly of claim 15, wherein the first prism pattern is formed along a length direction of the light source. The backlight assembly according to any one of claims 15 to 17; A liquid crystal panel disposed on the backlight assembly; And And a top case disposed on the liquid crystal panel and fastened to the bottom cover of the backlight assembly. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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