KR101277834B1 - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

The present invention discloses a backlight unit capable of realizing a thinning and making the luminance uniform.

The disclosed backlight unit includes a plurality of light sources arranged at regular intervals; And an optical plate disposed on the light source, wherein a light control pattern for controlling light is formed on one surface of the optical plate corresponding to the light source.

Diffusion Plate, Scattering, Luminance, Slim, Thin

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit and a liquid crystal display device having the same, which can realize thinning and uniform brightness.

In general, liquid crystal displays (LCDs) have tended to be gradually widened due to their light weight, thinness, and low power consumption. According to this trend, liquid crystal display devices are used in office automation equipment, audio / video equipment, and the like. The liquid crystal display device displays a desired image on the screen by controlling the amount of transmitted light according to a video signal applied to a plurality of control switches arranged in a matrix form.

Since the liquid crystal display device is not a self-luminous display device, a backlight unit for providing light to the back of a liquid crystal display panel on which an image is displayed is provided.

There are two types of the backlight unit, that is, a direct method and an edge method, depending on the position of a light source.

In the edge method, a light source is disposed on a side of a flat plate, and the light emitted from the light source is irradiated onto the entire surface of the liquid crystal display panel using a light guide plate. On the other hand, in the direct method, a plurality of light sources are disposed on the back of the liquid crystal display panel to directly irradiate light directly under the liquid crystal display panel, so that the luminance can be increased by a plurality of light sources compared to the edge method, and the light emitting surface is wider. There is an advantage to this.

As the size of the liquid crystal display device increases, the size of the backlight unit also increases. As a result, the liquid crystal display device employs a backlight unit of a direct type.

The backlight unit included in the general direct-type liquid crystal display device has a structure in which a plurality of light sources are arranged at a predetermined interval on the rear surface of the liquid crystal display panel, so as to improve the luminance difference between the area where the light source is disposed and the area where the light source is not disposed. By increasing the spacing of the diffusion plate disposed on the light sources and the light sources, it was possible to achieve uniform luminance.

Recently, technology development for developing a slimmer liquid crystal display device according to a user's request is in progress.

However, in the backlight unit of the direct type provided in the large liquid crystal display device, since the light source and the diffusion plate must maintain a sufficient distance in order to realize uniform brightness, the liquid crystal display device having a slim structure according to the user's request is required. There was a problem that was difficult to develop.

An object of the present invention is to provide a backlight unit having a uniform brightness.

Another object of the present invention is to provide a backlight unit having a slimmer structure and a liquid crystal display device having the same.

In a backlight unit according to an embodiment of the present invention,

A plurality of light sources arranged at regular intervals; And an optical plate disposed on the light source, wherein a light control pattern for controlling light is formed on one surface of the optical plate corresponding to the light source.

Further, in the liquid crystal display device of the present invention,

A plurality of light sources arranged at regular intervals; An optical plate disposed on the light source; And a liquid crystal display panel disposed on the optical plate, wherein a light control pattern for controlling light is formed on one surface of the optical plate corresponding to the light source.

According to the present invention, the density of the reflective pattern formed on the lower surface of the diffusion plate is larger than the area where the light source is not disposed, thereby achieving uniform brightness of the backlight unit.

In addition, the present invention has the effect that the density of the scattering pattern formed on the lower surface of the diffusion plate is larger than the region where the light source is arranged, the area where the light source is not arranged, it is possible to implement the brightness of the backlight unit uniformly.

In addition, the present invention provides a slim liquid crystal display device by reducing the overall thickness of the backlight unit by reducing the distance between the diffusion plate and the light source by providing a reflection pattern or a scattering pattern or a diffusion plate having the reflection pattern and the scattering pattern. Can be.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, embodiments of the present invention will be described in detail.

1 is an exploded perspective view showing a direct type liquid crystal display device according to a first exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a direct type liquid crystal display device taken along the line II ′ of FIG. 1. to be.

As shown in FIGS. 1 and 2, a direct type liquid crystal display device according to a first embodiment of the present invention is disposed on a liquid crystal display panel 100 on which an image is displayed and on a rear surface of the liquid crystal display panel 100. And a backlight unit 120 for irradiating light.

The liquid crystal display panel 100 includes a thin film transistor (TFT) substrate and a color filter substrate bonded together to maintain a uniform cell gap facing each other, and a liquid crystal layer interposed between the two substrates.

Although not shown in the drawing, the side of the liquid crystal display panel 100 is further provided with a driver (110, 111) for generating a drive signal for driving the liquid crystal display panel 100.

The backlight unit 120 according to the first embodiment of the present invention will be described as a direct method provided in a large liquid crystal display device of 20 inches or more as an example.

The backlight unit 120 includes a box-shaped bottom cover 180 having an upper surface opened, a plurality of light sources 150 disposed at regular intervals on the bottom cover 180, and the plurality of light sources 150. A diffusion plate 200 disposed on the diffusion plate 200 to diffuse light first, optical sheets 130 disposed on the diffusion plate 200 to collect and secondary diffuse light, and the plurality of light sources The reflective sheet 170 is disposed under the light source 150 to reflect the light traveling in the lower direction of the light sources 150 toward the liquid crystal display panel 100.

The backlight unit 120 includes first and second light source drivers 160a and 160b disposed at both ends of the plurality of light sources 150 to supply driving signals. The first and second light source drivers 160a and 160b may be mounted on the first and second driving PCBs 162a and 162b and the first and second driving PCBs 162a and 162b to provide light sources 150. It includes first and second sockets (164a, 164b) in contact with both ends of the.

The backlight unit 120 is disposed on both ends of the light sources 150 to guide the light emitted from the light sources 150 to the edge region of the liquid crystal display panel 100, and the diffusion plate 200 and the optical sheet. It further includes the first and second support side (140a, 140b) for supporting the field (160).

In the second embodiment of the present invention, the electrode is limited to an external eletrode fluorescent lamp (EEFL) covering the outer regions of both ends of the light sources 150, but is not limited thereto. A cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), or the like.

The diffusion plate 200 first diffuses the light emitted from the light source 150 to guide the first diffused light toward the optical sheets 130.

The diffusion plate 200 has a reflection pattern 203 formed on a lower surface corresponding to the direction in which the light sources 150 are disposed. The reflective pattern 203 is formed through ink printing.

The reflective pattern 203 has a predetermined shape (for example, a rhombus shape), and silver (Ag) having a high reflectance may be used as a material of the reflective pattern 203.

The individual pattern size of the reflective pattern 203 formed on the lower surface of the diffuser plate 200 corresponding to the light source 150 has a reflective pattern formed on the lower surface of the diffuser plate 200 that does not correspond to the light source 150. 203) larger than the individual size.

The lower surface of the diffusion plate 200 corresponding to the region where the light source 150 is disposed and the lower surface of the diffusion plate 200 corresponding to the region where the light source 150 is not disposed have a density of the reflective pattern 203. It is different. That is, the reflective pattern 203 corresponding to the region where the light source 150 is disposed has a higher density than the reflective pattern 203 corresponding to the region where the light source 150 is not disposed.

The diffusion plate 200 according to the first embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

3 is a perspective view illustrating a diffusion plate according to a first embodiment of the present invention, and FIG. 4 is a plan view illustrating a lower surface of the diffusion plate of FIG. 3.

3 and 4, the diffusion plate 200 according to the first embodiment of the present invention has a plurality of prismatic patterns 201 on the upper surface corresponding to the optical sheets 130 (see FIG. 2). The reflective pattern 203 having a different density for each region is formed on a lower surface corresponding to the light source 150.

The reflective pattern 203 has a rhombus shape and is formed by printing a material having a high reflectance such as silver (Ag). Here, in the first embodiment of the present invention, the shape and the material of the reflective pattern 203 are limited to rhombus and silver (Ag). It can be made in a variety of shapes, such as circular or round shape, any material having a high reflectance may be applied.

The size of the rhombus shape of the reflective pattern 203 becomes smaller from the area corresponding to the light source 150 toward the area not corresponding. That is, the reflective pattern 203 formed on the lower surface of the diffusion plate 200 has the largest size in the region corresponding to the light source 150 and has the smallest size in the region not corresponding to the light source 150. By adjusting the amount of transmission, uniform light transmission is induced for each region.

In other words, the reflective pattern 203 of the diffusion plate 200 controls the amount of light transmitted by adjusting the density of the region that does not correspond to the region corresponding to the light source 150.

A plurality of prismatic patterns 201 having peaks and valleys are formed on an upper surface of the diffusion plate 200. The prismatic pattern 201 has a rounded end portion of the mountain.

The prismatic pattern 201 is formed to extend in the longitudinal direction of the light source 150.

In the liquid crystal display device of the direct type according to the first embodiment of the present invention described above, the density of the reflective pattern 203 formed on the lower surface of the diffusion plate 200 is greater than that in which the light source 150 is not disposed. By increasing the enlarged area, the backlight unit 120 having a uniform luminance can be implemented.

In addition, the present invention includes a diffusion plate 200 formed on the bottom surface of the reflective pattern 203 to reduce the gap between the diffusion plate 200 and the light source 150, thereby reducing the overall thickness of the backlight unit 120 to slim One liquid crystal display device can be implemented.

5A to 5D are plan views illustrating lower surfaces of the diffusion plates according to the second to fifth embodiments of the present invention.

Referring to FIG. 5A, the diffusion plate according to the second embodiment of the present invention includes a scattering pattern 303 for scattering light on a lower surface corresponding to the light source 150.

The scattering pattern 303 is for scattering light, and the density of the region corresponding to the light source 150 is greater than the density of the region not corresponding to the light source 150.

The scattering pattern 303 is formed through a printing process, and includes a scattering material (eg, acrylic resin, transparent resin) for scattering light.

The scattering pattern 303 has a shape of at least three sides or a circle.

Referring to FIG. 5B, the diffusion plate according to the third embodiment of the present invention includes first to third scattering patterns 403a, 403b, and 403c having three different shapes.

The first to third scattering patterns 403a, 403b, and 403c have different pattern sizes of regions that do not correspond to the region corresponding to the light source 150, and regions where the density of the region corresponding to the light source 150 does not correspond. Is greater than the density.

Referring to FIG. 5C, the diffusion plate according to the fourth exemplary embodiment includes first and second scattering patterns 503a and 503b having two different shapes.

The first and second scattering patterns 503a and 503b are alternately formed at regular intervals in the longitudinal direction of the light source 150, and are uniform in the direction (the direction in which the light sources are arranged) corresponding to the longitudinal direction of the light source 150. It is formed alternately at intervals.

The densities of the first and second scattering patterns 503a and 503b are larger in areas not corresponding to the light source 150 than in areas corresponding to the light source 150.

Referring to FIG. 5D, the diffusion plate according to the fifth embodiment of the present invention may include scattering patterns 603a having three different shapes, and first and second reflection patterns 603b and 603c of the light source 150. The structure consists of alternating longitudinal directions.

The density of the scattering pattern 603a is larger in the area not corresponding to the light source 150 than in the area corresponding to the light source 150.

The densities of the first and second reflection patterns 603b and 603c are larger in areas corresponding to the light source 150 than in areas not corresponding to the light source 150.

In the above description, the backlight unit of the present invention is limited and described through five embodiments. However, the present invention is not limited thereto, and the reflective pattern or the scattering pattern formed on the rear surface of the diffusion plate may have more embodiments.

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

1 is an exploded perspective view illustrating a liquid crystal display device of a direct type according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a liquid crystal display device of a direct type cut along the line II ′ of FIG. 1.

3 is a perspective view showing a diffusion plate according to a first embodiment of the present invention.

4 is a plan view illustrating a lower surface of the diffusion plate of FIG. 3.

5A to 5D are plan views illustrating lower surfaces of the diffusion plates according to the first to fifth embodiments of the present invention.

Claims (14)

A plurality of light sources arranged at regular intervals; And An optical plate disposed on the light source, A light control pattern for controlling light is formed on one surface of the optical plate corresponding to the light source, and the light control pattern is formed of any one of a reflection pattern and a scattering pattern, and the size of any one of the reflection pattern and the scattering pattern is The backlight unit of claim 1, wherein the backlight unit is formed to increase or decrease from an area corresponding to the light source to an area not corresponding to the light source. delete The method according to claim 1, And the reflective pattern has a larger size of an area corresponding to the light source than an area not corresponding to the light source. The method according to claim 1, The scattering pattern is a backlight unit, characterized in that the size of the area that does not correspond to the light source is larger than the area corresponding to the light source. The method according to claim 1, And the light control pattern is a combination of a reflection pattern and a scattering pattern. The method according to claim 1, The light control pattern is a backlight unit, characterized in that having at least three sides or a round shape. The method according to claim 1, The light control pattern is a backlight unit, characterized in that the patterns of different shapes are formed alternately at regular intervals. A plurality of light sources arranged at regular intervals; An optical plate disposed on the light source; And A liquid crystal display panel disposed on the optical plate; A light control pattern for controlling light is formed on one surface of the optical plate corresponding to the light source, and the light control pattern is formed of any one of a reflection pattern and a scattering pattern, and the size of any one of the reflection pattern and the scattering pattern is And increase or decrease from an area corresponding to the light source to an area not corresponding to the light source. delete 9. The method of claim 8, And the reflection pattern has a larger size of an area corresponding to the light source than an area not corresponding to the light source. 9. The method of claim 8, And the scattering pattern has a larger size of an area not corresponding to the light source than an area corresponding to the light source. 9. The method of claim 8, And the light control pattern comprises a combination of a reflection pattern and a scattering pattern. 9. The method of claim 8, And the light control pattern has at least three sides or a round shape. 9. The method of claim 8, And the light control pattern is formed by alternating patterns of different shapes at regular intervals.

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