KR200446860Y1 - Back light assembly and liquid crystal display having the same - Google Patents

Abstract

A backlight assembly having improved luminance and a liquid crystal display device having the same are disclosed. The backlight assembly includes a light guide plate including a light source for generating light, a reflection surface having a reflection pattern for reflecting light incident from the light source, and an emission surface having an uneven surface for diffusing and emitting light reflected by the reflection surface. And a first prism sheet having a surface treatment layer for preventing adhesion to the exit surface. Accordingly, the backlight assembly may reduce the manufacturing cost by removing the diffusion sheet and provide light with improved brightness.

Description

BACK LIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

The present invention relates to a backlight assembly and a liquid crystal display device having the same, and more particularly, to a backlight assembly for providing light for displaying an image and a liquid crystal display device having the same.

In general, a liquid crystal display is a flat panel display that displays an image by using the electrical and optical characteristics of a liquid crystal having an intermediate characteristic between a liquid and a solid. It is thin and light, has a low driving voltage and low power consumption, and thus is widely used throughout the industry.

Such a liquid crystal display device requires a backlight assembly for supplying additional light because the liquid crystal display panel for displaying an image is a non-light emitting device that does not emit light by itself.

In general, the backlight assembly includes a light source, a light guide plate for guiding light emitted from the light source, a diffusion sheet disposed on the light guide plate to diffuse light emitted from the light guide plate, and a light collecting sheet for collecting diffused light emitted from the diffusion sheet. .

However, the diffusion sheet has a problem in that it causes a considerable ratio of light loss in the process of diffusing the light generated from the light source to lower the brightness.

Accordingly, the present invention has been made in view of such a problem, and an object of the present invention is to provide a backlight assembly capable of improving light utilization efficiency and reducing manufacturing costs.

Another object of the present invention is to provide a liquid crystal display device having the backlight assembly as described above.

The backlight assembly for achieving the above object of the present invention includes a light source for generating light, a light guide plate and a first prism sheet. The light guide plate may include a reflection surface having a reflection pattern for reflecting light incident from the light source, and an emission surface having concave-convex formation for diffusing and emitting light reflected by the reflection surface. The first prism sheet is disposed on the exit surface and has a surface treatment layer for preventing adhesion to the exit surface.

The backlight assembly further includes a second prism sheet having a light condensing direction different from that of the first prism sheet, and a reflective polarizing film disposed on the second prism sheet.

A liquid crystal display device for achieving another object of the present invention includes a backlight assembly and a liquid crystal display panel. The backlight assembly may include a light guide plate including a light source for generating light, a reflection surface having a reflection pattern for reflecting light incident from the light source, and an emission surface having an uneven surface for diffusing the light reflected by the reflection surface and outputting the light; And a first prism sheet disposed on the exit surface and having a surface treatment layer for preventing adhesion to the exit surface. The liquid crystal display panel displays an image using light supplied from the backlight assembly.

According to such a backlight assembly and a liquid crystal display device having the same, the manufacturing cost can be reduced by removing the diffusion sheet, and the luminance can be increased by improving light utilization efficiency.

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

1 is an exploded perspective view showing a backlight assembly according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing a coupling relationship of the backlight assembly shown in FIG. 3 is a cross-sectional view illustrating in detail the first prism sheet illustrated in FIG. 1.

1, 2 and 3, the backlight assembly 100 according to an embodiment of the present invention includes a light source 110 for generating light, a light guide plate 120 for guiding light emitted from the light source, and a light guide plate. It includes a first prism sheet 130 for collecting the light emitted from the.

The light source 110 is disposed on one side of the light guide plate 120 and includes, for example, at least one light emitting diode (LED).

The light guide plate 120 includes a reflection surface 122 that reflects light incident from a light source, and an emission surface 126 that diffuses and emits light reflected by the reflection surface.

The reflection surface 122 is formed with a fine reflection pattern for effectively reflecting the incident light toward the exit surface 126. The reflective pattern may be formed by various methods in various shapes for effectively reflecting light. For example, the reflective pattern is formed by printing the reflective dots 124 having a fine diameter using white ink. In this case, in order to improve appearance quality, the diameter of the reflective dots 126 may be smaller than 30 μm. In addition, in order to control the reflection path of the light to improve luminance uniformity, the closer to the light source 110, the lower the density per unit area, and the closer the contact, the higher the density is preferable.

The uneven surface 128 is formed on the exit surface 126 to effectively diffuse the light reflected by the reflective surface 122 to exit. Concave-convex 128 may be formed in an irregular size and irregular arrangement. The unevenness 128 may be formed by various processing methods. As an example, the concave-convex 128 is formed by a sand blast process. At this time, the height of the concave-convex 128 is preferably larger than 0.63㎛ and smaller than 1.6㎛ on average.

The light guide plate 120 is formed of a material capable of transmitting light. For example, the light guide plate 120 is formed of a poly methyl methacrylate (PMMA) material. PMMA is an acrylic resin containing methyl methacrylate (MMA) monomer as a main raw material. PMMA is excellent in transparency, weather resistance and colorability, and induces light diffusion when light is transmitted.

The first prism sheet 130 is disposed on the light guide plate 120. The first prism sheet 130 includes a base substrate 131 and prism patterns 132 having a triangular column shape disposed on an upper surface of the base substrate 131. The base substrate 131 is formed of a material such as polycarbonate (PC), polyethylene terephthalate (PET), or PMMA. The prism patterns 132 focus light emitted from the exit surface 126 of the light guide plate 120 to improve front brightness. The first prism sheet 130 includes a surface treatment layer 133 formed on a surface facing the exit surface 126 to prevent adhesion to the exit surface 126. The surface treatment layer 133 is formed of, for example, a coating liquid 135 including the beads 134. In addition, the surface treatment layer 133 may be formed by various methods such as forming irregularities on the surface.

The backlight assembly 100 further includes a second prism sheet 140 and a reflective polarizing film 150.

The second prism sheet 140 is disposed above the first prism sheet 130. The second prism sheet 140 condenses the light exiting through the first prism sheet 130 to further improve luminance. The second prism sheet 140 is formed to have a condensing direction different from that of the first prism sheet 130. For example, the second prism sheet 140 may be formed to have a light condensing direction perpendicular to the first prism sheet 130.

The reflective polarizer film 150 is disposed on the second prism sheet 140. For example, the reflective polarizing film 150 is formed of a dual brightness enhancement film (hereinafter referred to as DBEF). DBEF is a flexible thin film reflective polarizer, and its material is a polyester resin having a multi-layered structure. The DBEF focuses and polarizes light emitted through the first prism sheet 130 and the second prism sheet 140 in a single direction. As a result, the light utilization efficiency can be increased to greatly improve the luminance.

The backlight assembly 100 further includes a reflective sheet 160 and a storage container 170. The reflective sheet 160 is disposed on the reflective surface 122 side of the light guide plate 120 to reflect the light leaked to the reflective surface 122 to the exit surface 126 of the light guide plate 120. The reflective sheet 160 is formed of a material having high light reflectance. For example, the reflective sheet 160 is formed of a PET material. The light source 110, the reflector 160, the light guide plate 120, the first prism sheet 130, the second prism sheet 140, and the reflective polarizing film 150 are mounted in the storage container 170. The storage container 170 can be modified into various shapes as long as it can accommodate the above components.

4 is a plan view illustrating another example of the light guide plate illustrated in FIG. 1.

Referring to FIG. 4, a reflective pattern for effectively reflecting light incident from a light source is formed on the reflective surface 182 of the light guide plate 180. The reflection pattern is composed of fine linear reflection grooves 184. For example, the linear reflection grooves 184 are formed by laser processing. In this case, the linear reflection grooves 184 may be arranged at regular intervals or irregular intervals, and may have a constant direction and irregular direction. In addition, the linear reflection grooves 184 may be locally formed in different densities as necessary.

5 is an exploded perspective view showing a liquid crystal display according to an embodiment of the present invention. In the present embodiment, since the backlight assembly has the same configuration as that shown in FIG. 1, the same reference numerals are used for the same components, and detailed description thereof will be omitted.

Referring to FIG. 5, the liquid crystal display 1000 may include a backlight assembly 100 and a display unit 200.

The display unit 200 includes a liquid crystal display panel 210, a driving chip 220, and a flexible circuit unit 230. The liquid crystal display panel 210 includes a thin film transistor (hereinafter, referred to as TFT) substrate 212, a color filter substrate 214 coupled to the TFT substrate 212, and between the two substrates 212 and 214. And a liquid crystal 216 interposed therebetween.

The TFT substrate 212 is a transparent glass substrate on which a switching element TFT (not shown) is formed in a matrix form. Data and gate lines are respectively connected to the source and gate terminals of the TFTs, and a pixel electrode (not shown) made of a transparent conductive material is connected to the drain terminal. The color filter substrate 214 is a substrate in which RGB pixels (not shown) which are color pixels are formed by a thin film process. A common electrode (not shown) made of a transparent conductive material is formed on the color filter substrate 214. In the liquid crystal display panel 210 having such a configuration, when power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. Such an electric field changes the arrangement of the liquid crystals 216 interposed between the TFT substrate 212 and the color filter substrate 214, and transmittance of light supplied from the backlight assembly 100 in accordance with the arrangement change of the liquid crystal 216. Is changed to obtain an image of a desired gradation.

On at least one side of the TFT substrate 212, a driving chip 220 for applying a driving signal to the liquid crystal display panel 210 is mounted. The driving chip 220 may be composed of two or more chips separated into a data line chip and a gate line chip, or may be composed of a single chip integrating them, and may be formed of a TFT substrate (Chip On Glass) process. It is mounted on one side of 212). A flexible circuit unit 230 for applying a control signal for controlling the driving chip 220 is attached to one side of the TFT substrate 212 on which the driving chip 220 is mounted. The flexible circuit unit 230 includes a timing controller for adjusting the timing of the driving signal, a memory for storing the data signal, and the like, and is electrically connected to the TFT substrate 212 via an anisotropic conductive film.

The liquid crystal display 1000 may further include a top chassis 300. The top chassis 300 is coupled to the storage container 170 while surrounding the edge of the liquid crystal display panel 210 to fix the liquid crystal display panel 210 to the upper portion of the backlight assembly 100. The top chassis 300 prevents the liquid crystal display panel 210 from being damaged by an external impact and prevents the liquid crystal display panel 210 from being separated from the backlight assembly 100.

According to such a backlight assembly and a liquid crystal display having the same, by forming patterns for diffusing light on the reflective surface and the light emitting surface of the light guide plate, the manufacturing cost is reduced by eliminating the diffusion sheet, and the light loss due to the diffusion sheet is prevented. Brightness can be improved. In addition, by surface treatment on one surface of the first prism sheet facing the exit surface of the light guide plate, adhesion between the light guide plate and the first prism sheet can be prevented, thereby improving mechanical properties and product reliability. Furthermore, by providing the second prism sheet and the reflective polarizing film on the upper part of the first prism sheet, the light utilization efficiency and luminance can be improved.

In the above described with reference to the preferred embodiments of the present invention, those skilled in the art various modifications of the present invention without departing from the spirit and scope of the present invention described in the utility model registration claims below And can be changed.

1 is an exploded perspective view showing a backlight assembly according to an embodiment of the present invention.

2 is a cross-sectional view illustrating a coupling relationship of the backlight assembly illustrated in FIG. 1.

3 is a cross-sectional view illustrating in detail the first prism sheet illustrated in FIG. 1.

4 is a plan view illustrating another example of the light guide plate illustrated in FIG. 1.

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

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

100: backlight assembly 110: light source

120: Light guide plate 122: Reflective surface

126: exit surface 130: first prism sheet

140: second prism sheet 150: reflective polarizing film

160: reflective sheet 170: storage container

210: liquid crystal display panel 1000: liquid crystal display device

Claims (9)

A light source for generating light; A light guide plate including a reflection surface on which a reflection pattern for reflecting light incident from the light source is formed, and an emission surface on which an uneven surface is formed to diffuse and emit light reflected by the reflection surface; And And a first prism sheet disposed on the exit surface and having a surface treatment layer for preventing adhesion to the exit surface. The backlight assembly of claim 1, wherein the reflective pattern is formed of reflective dots having a diameter of less than 30 μm. The backlight assembly of claim 1, wherein the reflective pattern is formed of linear reflective grooves. The backlight assembly of claim 1, wherein the irregularities are formed by a sand blast process. The backlight assembly of claim 1, wherein the surface treatment layer is formed of a coating liquid including beads. The method of claim 1, A second prism sheet disposed on the first prism sheet and having a light condensing direction different from that of the first prism sheet; And And a reflective polarizing film disposed on the second prism sheet. A light guide plate including a light source for generating light, a reflection surface having a reflection pattern for reflecting light incident from the light source, and an emission surface having an uneven surface for diffusing and emitting light reflected by the reflection surface, and the emission surface A backlight assembly disposed on and including a first prism sheet having a surface treatment layer for preventing adhesion to the exit surface; And And a liquid crystal display panel for displaying an image using light supplied from the backlight assembly. The method of claim 7, wherein the backlight assembly A second prism sheet disposed on the first prism sheet and having a light condensing direction different from that of the first prism sheet; And And a reflective polarizing film disposed on the second prism sheet. The liquid crystal display device according to claim 7, wherein the reflective pattern is formed of reflective dots having a diameter of less than 30 µm.

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