KR20080047181A - Back-light assembly - Google Patents

Abstract

A back light assembly is provided to increase the brightness where the brightness is relatively lower than around by increasing the reflection ratio of light offered from the lamps. A lamp generates the light beam. A reflection member(170) is located at the lower portion of the lamp and reflects the light beam. The reflection ratio at the corner portion of the reflection member is higher than that at the center portion thereof. A receiving container(180) receives the lamp and the reflection member. A reflection pattern is formed at the corner portion and has the reflection pattern(172) with high reflection ratio compared to the reflection member. The reflection pattern is formed at the circumference of the ellipse having the center in the middle of the reflection member. The reflection pattern is formed at the center portion and has the reflection ratio lower than that of the reflection member. The reflection pattern is formed at the inside surface of the ellipse.

Description

Back-light assembly

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

2 is a perspective view illustrating a combination of a lamp, a reflective member, and a lower storage container included in the liquid crystal display of FIG. 1.

3A is a plan view of the reflective member and the lower housing of FIG. 2.

3B is a cross-sectional view of the reflective member and the lower housing of FIG. 2 taken along line III-III '.

4A is a plan view of a reflective member and a lower housing according to a second embodiment of the present invention.

4B is a cross-sectional view of the reflective member and the lower housing of FIG. 4A taken along line IV-IV ′.

5A is a plan view of a reflective member and a lower housing container according to a third embodiment of the present invention.

FIG. 5B is a cross-sectional view of the reflective member and the lower housing of FIG. 5A taken along the line VV ′. FIG.

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

10: liquid crystal display device 100: liquid crystal panel assembly

105: liquid crystal panel 110: upper storage container

120: backlight assembly 130: intermediate frame

140: optical sheet 150: diffuser plate

160: lamp 170, 270, 370: reflective member

172, 272, 372: reflective pattern 180: lower storage container

The present invention relates to a backlight assembly, and more particularly, to a backlight assembly for improving brightness uniformity of a liquid crystal display (LCD).

Liquid crystal display (LCD) is one of the most widely used flat panel display (FPD), and consists of two substrates on which electrodes are formed and a liquid crystal layer interposed therebetween. A display device adjusts the amount of light transmitted by rearranging liquid crystal molecules of a liquid crystal layer by applying a voltage to an electrode.

Since the liquid crystal display displays an image by using a liquid crystal, which is a light receiving element that does not emit light by itself, a device for separately supplying light is required. Therefore, the liquid crystal display receives light from the backlight assembly attached to the rear surface of the liquid crystal panel and displays an image. The backlight assembly is classified into a direct type and an edge type according to the position of the light source. Among the direct type backlight assembly, one or more lamps are arranged in a row on the lower surface of the diffuser plate to irradiate the entire liquid crystal panel with light. .

On the other hand, in the case of the direct type backlight assembly is provided with a reflecting member under the lamps arranged in a row, the lamp reflects the light emitted to the lower portion to supply the light to the diffusion sheet.

Such a direct backlight assembly has a difficulty in keeping the overall luminance of the diffuser plate uniform due to a structural problem that the lamp is a linear light source. In order to solve this problem, conventionally, a method of increasing the uniformity of luminance by forming a printing pattern on the lower surface of the diffusion plate has been proposed.

An object of the present invention is to provide a backlight assembly for improving luminance uniformity of a liquid crystal display (LCD).

The technical problem of the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The backlight assembly according to an embodiment of the present invention for achieving the above technical problem, the lamp for generating light, and positioned below the lamp to reflect the light and the reflectance of the corner portion is relatively higher than the reflectance of the center It includes a reflection member formed, and a storage container for storing the lamp and the reflection member.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a liquid crystal display according to a first exemplary embodiment of the present invention will be described with reference to FIG. 1. 1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention.

As shown in FIG. 1, the liquid crystal display 10 according to the first exemplary embodiment of the present invention includes an upper storage container 110, a liquid crystal panel assembly 100, and a backlight assembly 120.

The upper accommodating container 110 forms an exterior of the liquid crystal display 10, and an open window for exposing the liquid crystal panel assembly 100 to the outside is formed at the center thereof, and a bezel region is formed at the edge of the upper surface. It is.

The liquid crystal panel assembly 100 includes a liquid crystal panel 105, a gate tape carrier package 111, a data tape carrier package 112, and a printed circuit board 113.

The liquid crystal panel 105 serves to display an image on a screen by receiving an electrical signal, and the thin film transistor substrate 108 and the color filter substrate 107 are attached to face each other at regular intervals, and between the substrates. The liquid crystal layer is included in the formed space.

A plurality of gate lines and data lines are formed on the thin film transistor substrate 108, and the data lines are driven by a driving chip on the printed circuit board 113. The gate line is also driven by a gate line driver formed in the thin film transistor substrate 108.

The backlight assembly 120 includes an intermediate frame 130, an optical sheet 140, a diffuser plate 150, a lamp 160, a reflective member 170, and a lower storage container 180.

The backlight assembly 120 according to an embodiment of the present invention is a direct method in which the lamp 160 is arranged under the diffuser plate 150. Therefore, unlike the edge type backlight assembly in which the lamp 160 is disposed at the side and supplies light to the liquid crystal panel using the light guide plate, light is directly supplied from the lamp 160 to the liquid crystal panel 105. The bright line of the lamp 160 is displayed strongly, and in order to prevent the bright line of the lamp 160 from appearing, a thick diffusion plate 150 is used instead of a thin diffusion sheet.

The intermediate frame 130 accommodates the optical sheet 140, the diffusion plate 150, the reflective member 170, and the lamp 160 therein, and is seated and fixed to the lower storage container 180. 140, the diffusion plate 150, and the lamp 160 may be protected. The intermediate frame 130 is formed of sidewalls formed along a rectangular edge, and forms an open window at a central portion thereof so that light passing through the diffusion plate 150 and the optical sheet 140 can be transmitted.

The optical sheet 140 serves to diffuse and collect light transmitted from the diffuser plate 150, and is disposed on the diffuser plate 150 and received inside the intermediate frame 130. The optical sheet 140 includes a first prism sheet, a second prism sheet, and the like.

The first and second prism sheets refract the light passing through the diffusion plate 150 to concentrate the light incident at a low angle in front of the first prism sheet to improve the brightness of the liquid crystal display in the effective viewing angle range. Such a prism sheet may be used by two sheets to refract light in up, down, left, and right directions to maximize the effect. However, when one prism is sufficient, only one first prism may be used.

The diffuser plate 150 serves to diffuse light emitted from the lamp 160 in each direction so that bright lines appearing as bright portions along the shape of the lamp 160 are not visible from the front of the liquid crystal display 10. .

The lamp 160 generates light by a driving voltage applied by an inverter, and a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), an external electrofluorescent lamp (EEFL), and the like are used. In addition, the lamps 160 may be spaced at a uniform distance and connected in parallel to each other in phase, and may be configured in a direct type. It is preferable that the lamp 160 be arranged in the horizontal direction with respect to the liquid crystal panel 105 so that the distribution of the discharge gas inside the lamp 160 is constant to obtain uniform brightness.

The reflective member 170 reflects the light emitted in the downward direction of the lamp 160 toward the liquid crystal panel 105 and increases the efficiency of the light. The reflective member 170 is positioned below the lamp 160 and is well reflected. It is applied in color and may be used in the form of a reflecting plate in some cases. Detailed description of the reflective member 170 will be described later.

The lower housing 180 is combined with the intermediate frame 130 to protect the optical sheet 140, the diffusion plate 150, the lamp 160, and the like, and is positioned at the bottom of the backlight assembly 120. The optical sheet 140, the diffusion plate 150, the lamp 160, the reflective member 170, and the like are stored.

Hereinafter, the reflective member according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3B. 2 is a perspective view illustrating a combination of a lamp, a reflective member, and a lower housing included in the liquid crystal display of FIG. 1, FIG. 3A is a plan view of the reflective member and the lower housing of FIG. 2, and FIG. Sectional drawing which cut | disconnected the lower storage container with the III-III 'line | wire.

First, the reflective member 170 is positioned below the lamp 160, and a reflective pattern 172 having a higher reflectance than the surface of the reflective member 170 is formed on an upper surface thereof. The reflective member 170 is accommodated in the lower accommodating container 180 together with the lamp 160.

Specifically, the reflective pattern 172 is formed on the upper surface of the reflective member 170, thereby increasing the reflectance of the reflective member 170 to increase the efficiency of light. The reflective pattern 172 may improve luminance uniformity to be adjusted to uniform brightness on the entire surface of the reflective member 170 by adjusting the reflectance of a specific portion of the entire surface of the reflective member 170 higher or lower.

As in the first embodiment of the present invention, the direct type backlight assembly 120 having the lamp 160 directly below the diffuser plate 150 has a reflective member 170 in the lower storage container 180. ) It is arranged at regular intervals on the top. In this way, the plurality of lamps 160 are arranged in a circular cross-section, the luminance is uneven due to the arrangement of the lamp 160 as the length of the light source is formed very long compared to the diameter of the cross section.

Therefore, the cross section of the lamp 160 is circular, and the luminance non-uniformity can be reduced by suitably utilizing the light emitted radially in the normal direction to the circular surface.

In order to reduce such unevenness of luminance, the reflective pattern 172 is appropriately disposed on the reflective member 170 under the lamp 160 to increase the reflectance of the reflective member 170 under the lower luminance portion to further increase the reflectance. The brightness is maintained brightly, and if necessary, the reflectance of the reflective member 170 positioned below the high brightness portion is lowered to maintain the uniformity of the overall brightness.

That is, in the case of the direct type backlight assembly using the reflective member 170 on which the reflective pattern 172 is not formed, the luminance of the corner portion positioned at the edge of the backlight assembly 120 is lowest. As described above, the reflective member 170 according to the first exemplary embodiment of the present invention has a reflective pattern made of a metallic material having a gloss on the surface such as silver or aluminum, which is a material having high reflectance. 172). The reflective pattern 172 may use a variety of materials to represent the necessary reflectance according to the difference in luminance according to the arrangement of the lamp 160. Therefore, the materials presented above are merely exemplary, and any materials may be used as long as a material capable of increasing the brightness of the corner portion having a higher reflectance than the material applied to the reflective member 170 is used.

The reflective pattern 172 according to the first embodiment of the present invention is located at the corner of the reflective member 170. Considering the luminance characteristics of the direct backlight assembly 120, the reflective pattern 172 is formed at the corner portion to improve the luminance at the edge portion where the light of the lamp 160 reaches the weaker portion. It is preferable that the boundary line of the reflective pattern 172 positioned in the center direction of the curve forms a curved surface.

That is, the reflective pattern 172 formed at the corners of the reflective member 170 may be disposed inside an elliptical surface centered on the outline of the reflective member 170 and the center of the reflective member 170. .

However, since the arrangement may be variously changed according to the arrangement of the lamps 160, the arrangement may be arranged in a fan shape centering on each vertex of the corner portion, or in a triangle or square shape.

In addition, as illustrated in FIG. 3B, the reflective pattern 172 has a minute protrusion shape, and forms irregularities on the surface of the reflective member 170. The reflective pattern 172 may adjust the size, shape and density of the protrusions to effectively reflect light in a desired direction.

Meanwhile, in order to form the reflective pattern 172, a method such as silk screen printing, inkjet printing, or deposition may be used, and the color of the reflective pattern 172 may be changed according to the color of light emitted from the lamp 160. It may be.

The spacing of the reflective pattern 172 can be adjusted as needed. In other words, if the density of the reflective pattern 172 is increased, the reflectance is increased. On the contrary, if the density of the reflective pattern 172 is decreased, the reflectance is decreased. Accordingly, in consideration of an arrangement situation of the lamp 160, the size, shape, and density of the reflective pattern 172 are determined to maintain uniformity of luminance.

Hereinafter, the reflective member according to the second exemplary embodiment of the present invention will be described with reference to FIGS. 4A and 4B. 4A is a plan view of the reflective member and the lower housing container according to the second embodiment of the present invention, and FIG. 4B is a cross-sectional view of the reflective member and the lower housing container of FIG. 4A taken along line IV-IV '. For convenience of description, members having the same functions as the members shown in the drawings of the first embodiment are denoted by the same reference numerals, and therefore description thereof is omitted. The reflective member of this embodiment has a basically identical structure to the reflective member of the first embodiment except for the following.

That is, in the second embodiment of the present invention, in order to continuously adjust the overall brightness of the liquid crystal panel 105, the reflective pattern 272 is formed so that the reflectance gradually increases from the center of the reflective member 270 to the edge portion. Can be.

The reflective pattern 272 according to the second embodiment of the present invention forms the first region D ′, the second region D₂ and the third region D₃ according to the difference in reflectance, respectively. D ′), the second region D 2, and the third region D 3 are formed such that the reflectance increases as they are positioned at the corners of the reflective member 270.

As such, in order to form a difference in reflectance, the reflective pattern 272 may be formed of a different material for each region D ′, D₂ and D₃. In other words, the third region D₃ which should have the highest reflectance is coated with the material having the highest reflectance, and the second region D₂ is coated with the relatively low reflectance material, and then the first region D₁ is applied. ) Is coated with a material having a lower reflectance than the adjacent second region D2 but having a higher reflectance than the surface of the reflecting member 270, thereby gradually increasing the reflectance from the center to the corner of the reflecting member 270. .

In addition, in order to form a difference in reflectance between the first region D ′, the second region D₂ and the third region D₃, the first region D ′, the second region D₂ and the third region D₃ The density of the reflective pattern 272 formed in the can be adjusted. That is, the pattern is formed of a material having a higher reflectance than that of the reflective member 270, and the third region D₃ forming the corner portion may increase the density of the reflective pattern 272 to increase the overall reflectance, and the adjacent second region ( D2) relatively lowers the density of the reflective pattern 272, thereby gradually increasing the reflectance from the center of the reflective member 270 to the edge portion.

As described above, the reflective pattern 272 is characterized in that the reflectivity gradually increases from the center portion of the reflective member 270 to the corner portion, and the first region D ′, the second region D₂ and the first region D ′ are formed. The interface between the three regions (D₃) is not necessarily distinguished. In addition, since the first region (D₁), the second region (D₂), and the third region (D₃) are merely described in detail for convenience of explanation, the difference in reflectance between each region (D₁, D₂, D₃) is formed. It may be formed of one or more regions.

Hereinafter, the reflective member according to the third exemplary embodiment of the present invention will be described with reference to FIGS. 5A and 5B. 5A is a plan view of the reflective member and the lower housing container according to the third embodiment of the present invention, and FIG. 5B is a cross-sectional view of the reflective member and the lower housing container of FIG. 5A taken along the line V-V ′. For convenience of description, members having the same functions as the members shown in the drawings of the first embodiment are denoted by the same reference numerals, and therefore description thereof is omitted. The reflective member of this embodiment has a basically identical structure to the reflective member of the first embodiment except for the following.

That is, the reflective member 370 according to the third exemplary embodiment of the present invention forms the reflective pattern 372 with a material having a lower reflectance than the reflective member 370 in the central portion.

In order to uniformly adjust the luminance of the entire surface of the liquid crystal panel 105, the luminance variation of the central portion of the liquid crystal panel 105 showing relatively high luminance may be lowered to reduce the luminance variation of the entire surface of the liquid crystal panel 105.

In consideration of the luminance characteristics of the liquid crystal panel 105, a reflective pattern 372 is formed by applying a material having a lower reflectance than the surface of the reflective member 370 to a central portion of the reflective member 370. In order to control a bright point generated in a specific part of the entire surface of the liquid crystal panel 105, a reflective pattern 372 may be formed by applying a material having a low reflectance to the reflective member 370 directly below the bright point. Accordingly, the reflective pattern 372 may be formed to be limited to a specific position where bright spots occur, and the reflectance is changed by varying the density of the reflective pattern 372 in order to control the overall luminance, thereby changing the reflectivity of the liquid crystal panel 105. You can adjust the overall brightness.

Meanwhile, since the position, shape, and reflectance of the reflective pattern 372 are closely related to the position and arrangement of the lamp 160, the reflective pattern 372 may be formed in various ways in addition to the above-described embodiments.

While the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above embodiments and can be manufactured in different forms, and a person of ordinary skill in the art to which the present invention belongs It will be appreciated that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

As described above, according to the backlight assembly according to the present invention, the luminance uniformity of the liquid crystal display may be improved by increasing the reflectance of the light provided by the lamp to increase the luminance of the low luminance portion.

Claims (7)

Lamps for generating light; A reflecting member positioned below the lamp to reflect the light and formed such that a reflectance of a corner portion is relatively higher than that of a central portion; And And a storage container accommodating the lamp and the reflective member. The method of claim 1, And a reflective pattern having a higher reflectance than the reflective member is formed in the corner portion. The method of claim 2, The reflective pattern is formed on the outside of the ellipse having a center in the center of the reflective member. The method of claim 1, And a reflective pattern having a lower reflectance than the reflective member in the central portion. The method of claim 4, wherein The reflective pattern is formed on the inner surface of the ellipse having a center in the center of the reflective member. The method of claim 1, The edge portion has a higher density of the reflective pattern reflecting the light than the central portion. The method of claim 1, And a reflective pattern formed of a material having a high reflectance gradually from the center portion to the corner portion.

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