KR100634756B1 - Liquid Crystal Display having Light Guide Plate with a mesh pattern on lateral surfaces - Google Patents

Abstract

Disclosed is a liquid crystal display device in which scattering patterns are formed on both sides of a light guide plate to improve luminance and light uniformity. The LCD includes a light source, a backlight assembly formed at one side of the light source, a liquid crystal panel provided on the backlight assembly, and a mold frame for accommodating the backlight assembly and the liquid crystal panel. The backlight assembly includes a light guide plate and a reflection plate provided below the light guide plate to reflect the leaked light toward the liquid crystal panel. The light guide plate is composed of a light incident part to which light is introduced, an emitted light emitting surface, a rear surface opposite to the light emitting surface, and side surfaces positioned at both ends, and a scattering pattern for uniformly emitting light generated from the light source toward the light emitting surface. It is formed in. Thereby, the loss of the light incident on the side surface can be prevented and the brightness and uniformity of the light can be improved.

Description

Liquid crystal display having light guide plate with a mesh pattern on lateral surfaces}

1 is a perspective view showing a conventional backlight assembly structure.

FIG. 2A is a view illustrating the backlight assembly of FIG. 1 cut in an A ₁ -A ₂ direction. FIG.

Figure 2b is a backlight assembly according to figure 1 B ₂ - a view cut in the direction B _2.

3 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 4A is a view illustrating the liquid crystal display of FIG. 3 cut in the direction of A ₁ -A ₂ .

FIG. 4B is a view showing the liquid crystal display of FIG. 3 cut in the B ₂ -B ₂ direction.

FIG. 5 is a diagram illustrating an embodiment of a light guide plate having a scattering pattern printed on a side surface thereof.

6 is a view showing an embodiment of the scattering pattern distribution density on the side of the light guide plate according to the present invention.

7 is a view showing another embodiment of the present invention in which the side shape of the light guide plate is changed.

8 is a view showing an embodiment of a reflecting plate according to the present invention.                 

<Description of Symbols for Main Parts of Drawing>

212: liquid crystal display panel 220: backlight assembly

222: lamp 223: lamp reflector

224: light guide plate 224a: right side of the light guide plate

224b: Left side of light guide plate 224c: Back side of light guide plate

224 d: exit surface of the light guide plate 225: diffusion sheet

226: light collecting sheet 227: protective sheet

228: reflector 228a: rear reflector

228b: side reflector 229: scattering pattern

300: mold frame 400: chassis

The present invention relates to a liquid crystal display device, and more particularly, by modifying the shape and structure of the light guide plate of the backlight assembly, thereby improving the front luminance of the liquid crystal display device and at the same time preventing the light uniformity of the backlight assembly. And a liquid crystal display device using the same.

In general, a liquid crystal display device applies a voltage to a specific molecular array of liquid crystals and converts the same into another molecular array, and changes optical characteristics such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell that emit light by the molecular arrangement. It is a display using modulation of light by a liquid crystal cell by converting it into a visual change.

The liquid crystal display device is largely divided into TN (Twisted Nematic) and STN (Super-Twisted Nematic) methods, and due to the difference in driving method, an active matrix display method using a switching element and a TN liquid crystal and a passive matrix using STN liquid crystal There is a passive matrix display method.

The big difference between these two methods is that the active matrix display method is used for TFT-LCD, which drives the LCD using the TFT as a switch, and the passive matrix display method does not use transistors, thus requiring a complicated circuit. Do not

Since the liquid crystal display is a passive optical device that does not emit light by itself, an image is displayed by using a backlight assembly attached to the rear surface of the liquid crystal panel.

Recently, various structures have been developed for slimming and lightening in order to secure the competitiveness of the product. In particular, in view of the fact that the liquid crystal display device is mainly used in portable computers and the like, the weight reduction is treated more heavily.

In particular, the role and function of the backlight assembly have emerged as an important problem in the liquid crystal display device. Since the size and the light efficiency of the liquid crystal display device vary depending on the structure of the backlight assembly, the mechanical and optical characteristics of the overall liquid crystal display device are different. Because it is affected a lot. The backlight assembly is classified into a direct type and an edge type according to the position of the light source, and is divided into a flat type and an inclined type according to the shape of the light guide plate. In terms of weight reduction, brightness control and light uniformity, it is a general trend to adopt a backlight assembly having an inclined light guide plate of an edge type.

1 is a perspective view illustrating a conventional backlight assembly structure as described above, and FIG. 2A is a view illustrating the backlight assembly of FIG. 1 cut along an A ₁ -A ₂ direction, and FIG. 2B is a cut away along a B ₂ -B ₂ direction. Drawing. 1, 2A, and 2B, a conventional backlight assembly includes a lamp unit 100 and a light guiding unit 200, and the lamp unit 100 may include a lamp 110 and a lamp (for generating light). And a lamp reflector 120 surrounding the 110.

A cold cathode tube is mainly used as the lamp 110, and the light generated by the lamp 110 is incident through one side or both sides of the light guide plate 210.

In this case, since the light emitted from the lamp 110 is emitted toward the power main direction, the light emitted in the reverse direction with respect to the light guide plate 210 is reflected toward the light guide plate 210 to improve the efficiency of the light generated by the lamp 110. In order to provide the lamp reflector 120.

On the other hand, the light guide unit 200 is formed with a reflective plate 220, a light guide plate 210, a diffusion sheet 230, a plurality of light collecting sheets 240.

The light guide plate 210 is formed of a plastic-based transparent material such as acrylic to form a panel having an inclined rear surface and a horizontal exit surface (or, alternatively, an inclined exit surface and a horizontal rear surface), and the lamp ( The light generated from the 110 is directed toward the liquid crystal panel (not shown) which is seated on the upper portion via the exit surface of the light guide plate 210.

In this case, a light guide plate structure for improving luminance and uniformity of distribution of light traveling toward the liquid crystal panel is disclosed in US Pat. No. 5,178,447. According to this, the diffusion ink 212 is printed on the rear surface of the light guide plate 210 in a fine dot shape in order to convert the light incident into the light guide plate 210 into a surface light source in the liquid crystal panel direction. The dot-shaped diffusion ink 212 diffuses the incident light into the light guide plate 210 to set the incident angle of the light incident on the exit surface of the light guide plate 210 to be less than or equal to the threshold angle of the light guide plate 210. The output of light to a panel (not shown) is increased.

On the other hand, in order to improve the uniformity of the light incident on the liquid crystal panel (not shown), the dot is closer to the light source to form a rough pattern, the farther densely formed.

A reflecting plate 220 is formed on the rear surface of the light guide plate 210, and the diffusion sheet 230 and the plurality of light collecting sheets 240 are sequentially stacked on the exit surface of the light guide plate 210.

The reflecting plate 220 reflects the light, which is generated from the lamp 110 and proceeds to the rear surface of the light guide plate 210, not reflected by the diffusion ink 212 toward the exit surface of the light guide plate 210. As a result, the optical loss of the light incident on the liquid crystal panel (not shown) is reduced, and at the same time, the uniformity of the light transmitted to the exit surface of the light guide plate 210 is improved.                         

The diffusion sheet 230 positioned between the light guide plate 210 and the light collecting sheets 240 refracts outgoing light having a predetermined inclination with respect to the normal direction of the emission surface in the direction of the liquid crystal panel (not shown). Increase

The light collecting sheets 240 are disposed between the diffusion plate 230 and the liquid crystal panel (not shown) and include a plurality of sheets having a triangular prism-shaped prism in a predetermined arrangement. In general, the plurality of sheets are arranged such that prism arrays are staggered from each other at a predetermined angle, and the front luminance of the light incident toward the liquid crystal panel (not shown) is increased by narrowing the viewing angle of the light emitted from the diffusion sheet 230. The power consumption can be reduced. In general, the light collecting sheets 240 include a protective sheet for protecting a prism sheet, and the liquid crystal panel (not shown) is installed on the protective sheet.

However, in the conventional backlight assembly as described above, the diffusion ink for improving the brightness of the light toward the liquid crystal panel (not shown) is printed only on the rear surface of the light guide plate 210 as shown in FIG. Light reflected to the left and right sides of the 210 is difficult to limit the angle of incidence to the exit surface within the critical angle of the light guide plate 210, resulting in a decrease in brightness, the reflector 220 also the light guide plate 210 Installed only on the back side of the light reflected by the left and right side is eliminated there is a problem to reduce the light efficiency.

In addition, there is a problem that the uniformity of the light traveling in the direction of the liquid crystal panel (not shown) also decreases due to the difference in the intensity of the light reflected from the side near and far from the lamp 110.

Accordingly, an object of the present invention is to provide a liquid crystal display device having improved brightness and uniformity of light at corners and left and right sides of the light guide plate by applying a printing pattern to the left and right sides as well as the rear surface of the light guide plate.

In order to achieve the above object, the present invention, the light source for generating light and formed on one side of the light source, the light entering part and the emission surface is emitted, the rear surface facing the exit surface, located at both ends And a scattering pattern configured to uniformly emit light generated from the light source toward the emission surface in the light guide plate and the lower surface of the light guide plate. A backlight assembly having a reflector reflecting toward the exit surface; A liquid crystal panel provided on the backlight assembly; And a mold frame for accommodating the backlight assembly and the liquid crystal panel.

According to the present invention, a scattering pattern is formed not only on the back surface but also on the side surface of the light guide plate, thereby preventing the loss of light on the side surface of the light guide plate and improving the scattering characteristics, thereby realizing a liquid crystal display device having high light efficiency and front brightness.

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

3 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIGS. 4A and 4B illustrate A ₁ -A ₂ and B ₁ -B ₂ lines after completing the liquid crystal display according to FIG. 3. It is a section cut as a standard. Unless otherwise specified, the right side of the person looking at FIG. 4B is referred to as the right side, and the left side is referred to as the left side. The liquid crystal panel of FIG. 3 is referred to as upward and the mold frame direction is referred to as downward.

3, 4A, and 4B, the liquid crystal display includes a display unit 210 and a backlight assembly 220 for displaying an image by applying an image signal, and the display unit 210 and the backlight assembly 220. It consists of a mold frame 300 and a fixing chassis 400 for storing the.

The display unit 210 includes a liquid crystal display panel 212 and various printed circuit boards (not shown) for exchanging driving signals and data signals of the liquid crystal display device. The alignment angle of the liquid crystal injected into the display unit by the applied power is changed, and the light transmittance is changed according to the changed arrangement angle to obtain a desired pixel.

A backlight assembly 220 is provided below the display unit 210 to provide uniform light to the display unit 210.

The backlight assembly 220 includes a lamp unit and a light guide unit, and the lamp unit includes a lamp 222 and a lamp reflector 223, and the light guide unit includes a light guide plate 224, a reflector plate 228, and a light collecting sheet. Stream 226 and protective sheet 227.

A cold cathode tube is generally used as the lamp 222, and the light generated by the lamp 222 is incident on the light guide plate 224 through one side or both sides of the light guide plate 224. The lamp reflector 223 reflects the light generated from the lamp 222 toward the light guide plate 224.

The light guide plate 224 has a size corresponding to that of the liquid crystal panel 212 of the display unit 210 and is positioned below the liquid crystal panel 212 so that the lamp 222 side is thicker and farther from the lamp 222. The thin film is formed to change the path of the light while guiding the light generated by the lamp 222 toward the display unit 210.

The light guide plate 224 is formed of a plastic-based transparent material such as acrylic to form a panel having an inclined rear surface and a horizontal emission surface and a side surface perpendicular to the rear surface and the emission surface. The light guide plate 224 may be formed to have a wedge shape, or may be formed to have a planar shape when the lamp 222 is formed at both sides of the light guide plate 224.

5 illustrates an embodiment of a light guide plate having a scattering pattern printed on a side surface thereof.

Referring to FIG. 5, the light incident from the lamp 222 forms an angle of incidence within 0 ° to 42 ° by the critical angle characteristic of the material of the light guide plate 224, and the exit surface 224d of the light guide plate 224. The incidence angles at the and rear surfaces 224c and the side surfaces 224a and 224b are 48 degrees or more. Since the incident angle is larger than the critical angle of acrylic, the incident light is totally reflected inside the light guide plate 224, thereby repeatedly reflecting between the rear surface 224c and the exit surface 224d or the right surface 224a and the left surface 224b. It propagates to the end of the light guide plate 224. When the light propagated in the light guide plate 224 reaches the scattering pattern 229 printed on the rear surface 224c and the side surfaces 224a and 224b, the light traveling in one direction is diffusely reflected and diffused in various directions. Each time the reflections on the back surface 224c and the side surfaces 224a and 224b overlap, the incident angle of the incident light with respect to the exit surface 224d becomes small, which increases the component below the critical angle with respect to the exit surface. Facilitate exit from 224d). Thereby, the effect which also prevents the shortage of the emitted light of the area | region far from a light source can be achieved.

FIG. 6 is a diagram illustrating a distribution density of scattering patterns on the back and side surfaces of the light guide plate.

Since the projection ratio of the light source at the light source start point and the opposite end point is not uniform, and the edge portion of the light guide plate 224 close to the lamp 222 is brighter than other parts, the color of the liquid crystal panel becomes cloudy, and thus the light guide plate 224 The distribution density of the scattering patterns 229 formed on the back surface 224c and the side surfaces 224a and 224b of the Ns) is set smaller and thinner as the light entering the light incident portion, and larger and denser as the distance. Accordingly, the uniformity of light incident on the liquid crystal panel 212 may be improved.

FIG. 7 is a view showing another embodiment of the present invention in which the shape of the side surface of the light guide plate is changed to improve the brightness of light toward the liquid crystal panel.

Referring to FIG. 7, light incident on the left and right side surfaces 224a and 224b is formed to be inclined to form an acute angle between the emission surface 224d and the left and right side surfaces 224a and 224b of the light guide plate 224. The luminance of the edge portion of the liquid crystal panel may be improved by increasing the components reflected to the left and right edge portions of the 212.

The normal vector of the left and right sides 224a and 224b serving as a reflection axis for the incident light is inclined at a predetermined angle from the state parallel to the exit surface 224d so that the left and right sides 224a and 224b of the light guide plate are inclined. When the incident light is reflected, the component reflected to the edge of the liquid crystal panel 212 is increased. Therefore, the luminance of the edges and corners of the liquid crystal panel 212 can be improved.

 The reflective plate 228 is formed on the lower side and the left and right side surfaces 224a and 224b of the light guide plate 224 having the above-described configuration, and the reflective plate 228 is the scattering pattern 229 of the light guide plate 224. By reflecting the light leaked to the lower and left and right sides of the light guide plate 224 without being reflected in the direction of the liquid crystal panel 212 back to the liquid crystal panel 212.

FIG. 8 illustrates an embodiment of a reflector according to the present invention, and includes a light guide plate rear reflector 228a and a light guide plate side reflector 228b, and the rear reflector 228a and the side reflector 228b are formed. It may be formed integrally or may be formed separately from each other.

The light reflected by the scattering pattern 229 and the reflecting plate 228 formed on the rear surface 224c and the left and right side surfaces 224a and 224b of the light guide plate 224 is formed by the liquid crystal panels 212 and 24 and the liquid crystal panel. The optical sheets placed between 212 are composed of a diffusion sheet 225, a plurality of prism sheets 226, and a protective sheet 227.

The diffusion sheet 225 disposed between the light guide plate 224 and the plurality of prism sheets 226 prevents light from being partially concentrated by dispersing light incident from the light guide plate 224. In addition, the diffusion sheet 225 also serves to reduce the inclination angle of the prism sheet 226 toward the prism sheet 226.                     

Each of the plurality of prism sheets 226 has a prism of a triangular prism shape formed on a top surface thereof, and the prism arrangement of the top sheet and the prism arrangement of the bottom sheet are arranged to be staggered with each other at a predetermined angle.

Each of the plurality of prism sheets 226 collects light diffused from the diffusion sheet 225 in a direction perpendicular to the plane of the liquid crystal panel 212, and thus passes through the prism sheet 226. Vertical incidence of light to the protective sheet 227 may be secured.

Accordingly, the light passing through the prism sheet 226 proceeds vertically so that the luminance distribution on the protective sheet 212 is uniformly obtained.

The protective sheet 227 formed on the plurality of prism sheets 226 not only serves to protect the surface of the prism sheet 226, but also diffuses light to uniformize the distribution of the light. Perform. In this case, the liquid crystal panel 212 is installed on the protective sheet 227.

The backlight assembly 220 and the liquid crystal panel 212 including the lamp unit and the light guide unit are seated in the mold frame 300.

The mold frame 300 accommodates and fixes the backlight assembly 220 and the liquid crystal panel 212, and prevents the backlight assembly 220 including the plurality of sheets from being bent. A plurality of support parts are formed to form a portion in which the printed circuit board (not shown) of the liquid crystal panel 212 contacts.                     

A chassis 400 is provided to fix the display unit 210 and the backlight assembly 220 on the mold frame 300. The chassis 400 has a rectangular parallelepiped shape like the mold frame 300, and an upper surface of the chassis 400 is opened to expose the liquid crystal panel 212, and a side wall of the chassis 400 is bent in an inner vertical direction to form an upper surface of the liquid crystal panel 212. Cover the perimeter.

The liquid crystal display according to the present invention is completed by mounting a front case and a rear case (not shown) having an opening for exposing the liquid crystal panel 212 to the mold frame 300 to which the chassis 400 is coupled.

Therefore, the liquid crystal display according to the present invention can improve the luminance at the corners of the liquid crystal panel and the left and right sides by printing scattering patterns on the side of the light guide plate as well as on the side surface of the liquid crystal panel. Can be improved.

According to the present invention, the scattering pattern is printed on both the left and right sides of the light guide plate constituting the backlight assembly for the liquid crystal display device to promote diffuse reflection on the left and right sides, thereby improving luminance in the liquid crystal panel, and By adjusting the density according to the distance from the light source, the light uniformity can be improved. In addition, the side surface is inclined at a predetermined angle to improve the luminance of the edge portion of the liquid crystal panel.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (5)

a) a light source for generating light, and iii) a light source formed on one side of the light source, comprising a light incident portion into which light is introduced, an emission surface emitted, a rear surface opposite to the emission surface, and side surfaces positioned at both ends thereof; A light guide plate having a scattering pattern for uniformly emitting light generated from the light emitting plate in a direction toward the emission surface; c) provided at a lower portion of the light guide plate, and reflecting light leaked from the rear surface toward the emission surface; The backlight assembly having a reflector; A liquid crystal panel provided on the backlight assembly; And And a mold frame for accommodating the backlight assembly and the liquid crystal panel. The liquid crystal display device according to claim 1, wherein the scattering pattern has a dot shape. The liquid crystal display device according to claim 1, wherein the scattering pattern formed on the side surface has a larger distribution density as it is farther from the light incident portion. The liquid crystal display device according to claim 1, wherein the side surface is inclined with respect to the rear surface and the emission surface. The liquid crystal display device according to claim 1, further comprising a reflector formed on an outer side of the side surface.

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