KR20070113577A - Back light assembly - Google Patents

Abstract

A back light assembly is provided to enable a brightness equalizing unit to disperse and radiate light emitted from a point light source uniformly to the whole of a light guide plate, thereby preventing a light leakage and making brightness uniform. A back light assembly includes point light sources, a light guide plate(220), and first dots(232a,232b). The point light sources generate light. The light guide plate includes a light incident surface facing the point light sources and a light emitting surface where a guided light is emitted. The first dots are an achromatic color and are formed in the light emitting surface adjacent to the point light sources. The first dots are formed on the light emitting surface corresponding to the point light sources out of light emitting surfaces adjacent to the point light sources.

Description

Backlight Assembly {BACK LIGHT ASSEMBLY}

1 is a cross-sectional view of a display device according to an exemplary embodiment of the present invention.

2 is a plan view of a light guide plate according to an exemplary embodiment of the present invention.

3 is a plan view of a light guide plate according to another exemplary embodiment of the present invention.

4 is a cross-sectional view of dots printed on the light guide plate.

5 is a cross-sectional view in which the luminance equalizer is attached to the light guide plate.

6 is a plan view of a light guide plate according to another embodiment of the present invention.

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

500: display device 100: display unit

200: backlight assembly 210: point light source

220: LGP 230a, 230b: luminance equalization unit

232a, 232b: dots 234, 235: adhesive member

240: reflective sheet 300: storage container

The present invention relates to a backlight assembly, and more particularly, to a backlight assembly having a uniform brightness to improve display quality.

In general, a liquid crystal display device includes a liquid crystal display panel including an array substrate, a color filter substrate, and a liquid crystal layer, and a backlight assembly for providing light required for performing the display of the liquid crystal display panel.

The LCD displays an image by using the electrical and optical characteristics of the liquid crystal. Since the liquid crystal used in the liquid crystal display does not generate light by itself and only adjusts the transmittance of the light, the liquid crystal display needs light to perform the display. As a result, a normal liquid crystal display device is provided with a backlight assembly that provides light for display.

The backlight assembly includes a lamp unit, a light guide plate and optical sheets. The lamp unit generates light required by the liquid crystal display panel, and a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) is used as a light source of the lamp unit. The light emitting diode is smaller than other light sources, has a long lifetime, and has low power and good efficiency because electrical energy is directly converted into light energy.

However, since the light emitting diode has a limited brightness per light emitting diode, a plurality of light emitting diodes must be used in parallel or in parallel to each other. There is a problem that is not distributed.

Accordingly, the technical problem of the present invention was conceived in this respect, and an object of the present invention is to provide a backlight assembly with uniform luminance.

According to an embodiment of the present invention, a backlight assembly includes: a light guide plate including point light sources for generating light, an entrance surface facing the point light sources, and an exit surface for guided light; Achromatic first dots formed on the emission surface adjacent to the point light sources.

According to the backlight assembly, the dots may remove light leakage that leaks to the edges of the display panel and change the color of the dots within the achromatic range to make the luminance uniform. As a result, the display quality of the display panel can be improved.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention.

1 is a cross-sectional view of a display device according to an exemplary embodiment of the present invention.

2 is a plan view of a light guide plate according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the display device 500 includes a display unit 100 for displaying an image, a backlight assembly 200, and a storage container 300 for storing the display unit 100 and the backlight assembly 200. .

The display unit 100 includes display panels 110 and 120 for displaying an image and a driving circuit unit (not shown) for providing a driving signal to the display panels 110 and 120. The display panels 110 and 120 may include an array substrate 100 including a switching element (not shown), a color filter substrate 120 facing the array substrate 110, and an array substrate 110 and a color filter substrate 120. It includes a liquid crystal layer (not shown) interposed between).

The display unit 100 may further include polarizers (not shown) formed below the array substrate 110 and above the color filter substrate 120. The display panels 110 and 120 are divided into a display area in which the array substrate 100 and the color filter substrate 120 overlap and a peripheral area formed around the display area. The driving circuit unit is formed on the array substrate 100 in the peripheral area to provide driving signals to the display panels 110 and 120.

The backlight unit 200 is provided below the display unit 100 to provide uniform light to the display panels 110 and 120. The backlight assembly 200 may include the point light sources 210 for generating light, the light guide plate 220 for emitting light emitted by the point light sources 210 in the direction in which the display unit 100 is formed, and the reflective sheet 240. And optical sheets 252 and 254.

The light guide plate 220 guides the light emitted from the point light sources 210 disposed on the side of the backlight assembly 200 and emits the light in the direction in which the display unit 100 is formed. The light guide plate 220 is perpendicular to the entrance plane 222 facing the point light sources 210, the exit plane 224 connected to the entrance plane 222, and the entrance plane 222, and is perpendicular to the exit plane 224. And a parallel bottom surface.

Light emitted from the point light sources 210 is incident on the light guide plate 220 through the incident surface 222, and the light incident on the incident surface 222 is guided and exits to the exit surface 224. The light guide pattern 226 is formed on the lower surface to guide the light passing through the incident surface 222 toward the exit surface 224 through the light guide pattern 226.

Optical sheets 252 and 254 are formed on an upper surface of the exit surface 224 of the light guide plate 220, and a reflective sheet 240 is formed below a lower surface of the light guide plate 220 parallel to the exit surface 224. do. The optical sheets 252 and 254 change a path of light emitted from the light guide plate 220 to the display panels 110 and 120 to improve luminance characteristics of the light.

For example, the optical sheets 252 and 254 include a diffusion sheet 252 for diffusing light and a prism sheet 252 for collecting light. The reflective sheet 240 reflects the light leaking under the light guide plate 220 toward the exit surface 224 of the light guide plate 220 to increase the light utilization efficiency.

The storage container 300 extends from the bottom surface 310 and the bottom surface 310, and includes a plurality of sidewalls 320 formed perpendicular to the bottom surface 310. The display unit 100 and the backlight assembly 200 are accommodated in a space formed by the bottom surface 310 and the side wall 320. The storage container 300 may be made of various materials having strong strength, and is preferably made of a metal material.

1 and 2, the light guide plate 220 includes a luminance equalizer 230 formed on the emission surface 222 adjacent to the point light sources 210. The luminance equalizer 230 is formed in the area of the emission surface 224 adjacent to the point light source 210 among the emission surface 224.

The luminance equalizer 230 may display a region of the emission surface 224 adjacent to the point light source 210 relatively brighter than an area of the other emission surface 224 or light leakage in an area of the emission surface adjacent to the point light source 210. This is prevented from occurring and the luminance is made uniform throughout.

The luminance equalizer 230 is formed by dispersing any one color of black dots and white dots to facilitate reflection and scattering of light. Alternatively, the black dots and the white dots are combined to form a dispersion.

Hereinafter, when the color from white to gray is defined as white among achromatic colors having lightness but no hue or saturation, the color from gray to black will be defined as black.

The luminance equalizer 230 blocks light emitted from the point light source 210 directly leaking to the display panels 110 and 120. The luminance equalizer 230 corrects the amount of light biased to the display panels 110 and 120 adjacent to the point light source 210 to uniform the luminance, and at the display panels 110 and 120 adjacent to the point light source 210. It prevents the locally occurring light leakage phenomenon.

The white dots are formed on an area of the display panel 110 and 120 that appears to be relatively brighter than other areas, for example, on the emission surface 224 adjacent to the point light source 210, and thus, from the point light source 210. Reflect the light emitted.

In particular, in the case where the light passing through the display panels 110 and 120 is locally biased to the exit surface 224 adjacent to the point light source 210, when the white dots are formed on the exit surface 224, the white dots are formed. The light reflected from the dots redirects the light to a region distant from the emission surface 224 adjacent to the point light source 210 through the light guide pattern 226 of the lower surface of the light guide plate 220.

The black dots absorb or reflect light emitted from the point light source 210 to block the path of the light passing through the exit surface 224 adjacent to the point light source 210. The white dots and the black dots vary a region formed in the emission surface 224 along the path of the light passing through the light guide plate 220.

Referring to FIG. 2, the luminance equalizer 230 of the LGP 220 according to an exemplary embodiment may include a first luminance equalizer 230a and a black dot 232b formed of white dots 232a. And a second luminance equalizer 230b. Unlike the exemplary embodiment of the present invention, only one of the first luminance equalizer 230a and the second luminance equalizer 230b may be formed on the emission surface 224.

The first luminance equalizer 230a and the second luminance equalizer 230b may include relatively bright areas among the emission surfaces 224 adjacent to the first, second, and third point light sources 210a, 210b, and 210c. Form to correct relatively dark areas. In detail, the movement path of the light emitted from the first point light source 210a is such that the light reaches the incident surface 222 within a predetermined angle, for example, about 120 degrees, around the first point light source 210a.

Among the emission surfaces 224 adjacent to the first, second, and third point light sources 210a, 210b, and 210c, relatively bright areas are defined by the first, second, and third point light sources 210a, 210b, and 210c. The corresponding emission surface 224, and the relatively dark area is the emission surface 224 corresponding between the first point light source 210a and the second point light source 210b adjacent to the first point light source 210a.

Accordingly, the first luminance equalizer 230a is formed in the region corresponding to the first, second, and third point light sources 210a, 210b, and 210c of the emission surface 224, respectively, and the second luminance equalizer ( 230b is formed in at least one of a region corresponding to between the first point light source 210a and the second point light source 210b and a region corresponding to between the second point light source 210b and the third point light source 210c. do.

The light reflected by the white dots 232a of the first luminance equalizing unit 230a is provided from an area of the emission surface 224 adjacent to the first, second, and third point light sources 210a, 210b, and 210c. The path of light is diverted to the area of another exiting surface 224 away. The light absorbed by the black dots 232b of the second luminance equalizer 230b does not pass through the emission surface 224 and the light is blocked to uniformly correct the overall luminance of the display panels 110 and 120. .

Meanwhile, the first, second, and third point light sources 210a, which are not shown in the form of the first luminance equalizing unit 230a independently, may be formed of a white tape (not shown) that serves as the first luminance equalizing unit 230a. It is attached to the exit surface 224 adjacent to 210b and 210c. When the second luminance equalizer 230b is formed on the white tape, the emission surface 224 adjacent to the first, second, and third point light sources 210a, 210b, and 210c to which the white tape is attached may be formed. Reflection and scattering occur, and at the same time, the dots 232b of the second luminance equalizer 230b absorb light.

3 is a plan view of a light guide plate according to another exemplary embodiment of the present invention.

Referring to FIG. 3, the light guide plate 220 includes an incident surface 224 having an uneven pattern. Since the incident surface 224 includes the concave-convex pattern, the amount of light that is biased toward a region corresponding to the first, second, and third point light sources 210a, 210b, and 210c of the light guide plate 220 is measured. The path of the light may be changed to a region corresponding to the first point light source 210a and the second point light source 210b. The uneven pattern may be formed in the entire incident surface 224 or in an area of the incident surface 224 corresponding to the first, second and third point light sources 210a, 210b, and 210c.

In the case of the light guide plate 220 according to another embodiment of the present invention, an area corresponding to the first point light source 210a and the second point light source 210b of the light guide plate 220, as opposed to the embodiment of the present invention. The light may be biased. In order to prevent such a phenomenon of polarization of the light, the luminance equalizers 230a and 230b are formed on the emission surface 224.

According to another embodiment of the present invention, the luminance equalizers 230a and 230b are formed on the emission surface 224 adjacent to the first, second, and third point light sources 210a, 210b, and 210c, and each point light source ( The first luminance equalizer 230a formed in a region corresponding to 210a, 210b, and 210c includes black dots 234b.

The second luminance equalizer 230b formed in a region corresponding to the first point light source 210a and the second point light source 210b includes white dots 234a. Unlike other embodiments of the present invention, only one of the first luminance equalizer 230a and the second luminance equalizer 230b may be formed according to the light guide plate 220.

On the other hand, it is possible to form a different size of the dots, or to adjust the spacing between the dots to adjust the reflectance or absorbance. For example, when the size of the dot is large, the area to be reflected is larger than when the size of the dot is small, thereby increasing the rate at which the light is reflected or absorbed. The size of the dots is preferably smaller as the distance between the first, second and third point light sources 210a, 210b, 210c and the exit surface 224 increases.

In addition, when the distance between the dots is closer, the ratio of the reflection or absorption of the light may be increased than when the distance between the dots is far. For example, as the first, second and third point light sources 210a, 210b, and 210c move away from each other, the smaller and smaller sizes of the dots may be formed to reduce the reflection or absorption rate of the light.

4 is a cross-sectional view of dots printed on the light guide plate.

5 is a cross-sectional view in which the luminance equalizer is attached to the light guide plate.

The luminance equalizer 230 prints the dots 232 on the emission surface 224 of the light guide plate 220 or attaches the adhesive members 233 and 234 including the dots 232 to the emission surface 224. It can be formed as. Forming the luminance equalizer 230 by attaching the printed film 233 to the dots 232 is more advantageous than the case where the dots 232 are printed on the emission surface 224. It is easy to change and can be easily modified.

Referring to FIG. 4, in the method of printing the dots 232 on the emission surface 224, a plurality of grooves are formed on the emission surface 224, and the luminance is uniformed by forming ink by filling the grooves. do. The plurality of grooves substantially become dots 232, and fill the grooves with color ink of any one of black, gray, and white to form the luminance equalizer 230. Alternatively, the luminance equalizer 230 may be formed by directly printing the dots 232 on the emission surface 224.

Referring to FIG. 5, the luminance equalizer 230 may include first adhesive members 233 and 234 on which dots 232 are formed. For example, the first adhesive members 233 and 234 may include a film 233 printed with dots 232 and a transparent adhesive applied to the film 233, and the first adhesive member 234 may have an exit surface 224. ) To form the luminance equalizer 230.

The film 233 is formed of, for example, a polycarbonate material. The transparent adhesive 234 is formed using an acrylic material of a transparent material. The printed film 233 is coated with a transparent adhesive 234 on both sides, one surface is attached to the exit surface 224, the other surface and the other surface may be attached to the optical members (252, 254).

The transparent adhesive 234 is uniformly coated on the surfaces of the first adhesive members 233 and 234, but includes the fine concavo-convex rather than the completely flat surface, so that the light emitted from the light sources is the first adhesive member. It may be reflected and scattered by the concavities and convexities on the surface of 233 and 234.

A path of light in the light guide plate including the luminance equalizer 230 will be described in detail with reference to FIGS. 1, 4, and 5. Hereinafter, the path of light indicates that the light is reflected and scattered in the white dots.

Referring to FIG. 1, the first light L1 emitted from the point light source 210 passes through the incident surface 222 and moves toward the exit surface 224 by the light guide pattern 226. Light directed toward the display panels 110 and 120 is uniformly distributed by the plurality of lights having the same movement path as the first light L1.

However, in the conventional light guide plate, light emitted from the point light source 210 is directly moved to the display panels 110 and 120, or the light is biased toward the display panels 110 and 120 adjacent to the point light source 210. Accordingly, light leakage occurs in the display panels 110 and 120 adjacent to the point light source 210.

In the case of the light guide plate 220 in which the luminance equalization unit 230 is formed as in the embodiment of the present invention, the second light L2 emitted from the point light source 210 is connected to the point light source 210 by the light guide pattern 226. Even if it moves toward the adjacent emission surface 224, the second light L2 is reflected and scattered by the luminance equalizer 230.

Specifically, the luminance equalizing unit 230 is a region in which the dot 232 is formed and an area in which the dot 232 is not formed between the one dot 232 and the other dot 232 form one pattern. The light moving to the area where) is formed moves to the exit surface 224 far from the point light source 210.

The light moving to the luminance equalizer 230 in the region where the dot 232 is not formed passes through the emission surface 224 to the display panels 110 and 120 adjacent to the point light source 210. Accordingly, it is possible to prevent the light leakage phenomenon from occurring on the emission surface 224 adjacent to the point light source 210 by the luminance equalizer 230.

For example, referring to FIGS. 1, 3, and 4, the third light L3 emitted from the point light source 210 and directed toward the emission surface 224 adjacent to the point light source 210 may be a luminance equalization unit ( Reflected and scattered at 230, the light is moved to the exit surface 224 relatively far from the point light source 210.

The fourth light L4 emitted from the point light source 210 and directed toward the exit surface 224 adjacent to the point light source 210 is interposed between one dot 232 and another dot 232 adjacent to the dot 232. The fifth light L5 passing through and emitted from the point light source 210 toward the exit surface 224 adjacent to the point light source 210 through the light guide pattern 226 is also different from the one dot 232. Pass through). Accordingly, it is possible to correct the bias of the light toward the exit surface 224 adjacent to the point light source 210.

On the other hand, the light emitted from the point light source 210 is not shown the path of the light absorbed or reflected in the black dots, the ratio of the black dots absorb the light or reflected from the white dots Rather, the light may be reflected at a lower ratio to block the path of the light from the emission surface 224 and the display panels 110 and 120 or to minimize the amount of light.

6 is a plan view of a light guide plate according to another embodiment of the present invention.

Referring to FIG. 6, the luminance equalizers 230a and 230b are formed on the edges of the emission surface 224 as well as the emission surface 224 adjacent to the point light source. The third luminance equalizer 230c is formed by attaching the second adhesive member 235 to the emission surface 224. The third luminance equalizer 230c is formed to include dots having at least one color of white dots and black dots.

According to such a backlight assembly, by forming a luminance equalization unit consisting of a plurality of dots on the emission surface of the light guide plate, the luminance equalization unit uniformly disperses the light emitted from the point light source to the entire light guide plate.

As a result, light leakage from light leaking out of a portion of the display panel adjacent to the point light sources can be prevented, and light leakage from light leaking from the edge of the display panel can be prevented, thereby making the luminance uniform. Accordingly, the display quality of the display panel and the reliability of the product can be improved.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (11)

Point light sources for generating light; A light guide plate including an incident surface facing the point light sources and an exit surface from which guided light is emitted; And And achromatic first dots formed on an emission surface adjacent to the point light sources. The backlight assembly of claim 1, wherein the first dots are formed on an emission surface corresponding to the point light source among the emission surfaces adjacent to the point light sources. The backlight assembly of claim 2, wherein the first dots are white. The backlight assembly of claim 1, wherein the first dots are formed on an emission surface corresponding between a first point light source and a second point light source adjacent to the first point light source. The backlight assembly of claim 4, wherein the first dots are black. The backlight assembly of claim 1, wherein an uneven pattern is formed on an incident surface of the light guide plate. The backlight assembly of claim 6, wherein the first dots formed on the emission surface corresponding to the point light source among the emission surfaces adjacent to the point light sources are white. 7. The backlight assembly of claim 6, wherein the first dots formed on the emission surface corresponding between the first point light source and the second point light source adjacent to the first point light source are black. The backlight assembly of claim 1, wherein the size of the first dots decreases as the distance from the point light sources increases. The backlight assembly of claim 1, further comprising second dots formed at an edge of an exit surface of the light guide plate and having the achromatic colors. The backlight assembly of claim 10, wherein the first and second dots are printed on an adhesive member and adhered to the exit surface.

Images