KR20070044095A - Backlight assembly and liquid crystal display apparatus having the same - Google Patents

Abstract

A backlight assembly capable of improving optical characteristics and a liquid crystal display device having the same have been disclosed. The backlight assembly includes a light source and a light guide plate for generating light. The light guide plate includes an incident surface that receives light from the light source, an exit surface vertically extending from one side of the incident surface, and a reflection surface extending from the other side of the incident surface so as to face the exit surface. The reflective surface is provided with a plurality of protrusions and line-shaped fine concavo-convex pattern protruding to a predetermined height. Therefore, the optical characteristics of the backlight assembly may be improved by the protrusions and the fine concavo-convex pattern.

Description

BACKLIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY APPARATUS HAVING THE SAME}

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

FIG. 2 is a perspective view illustrating a rear surface of the light guide plate shown in FIG. 1.

3 is an enlarged view of a portion of the patterns illustrated in FIG. 2.

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

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

100: backlight assembly 200: light source

300: light guide plate 310: incident surface

320: reflective surface 322: fine uneven pattern

324: projection 330: exit surface

410: reflection sheet 420: diffusion sheet

430: luminance enhancement sheet 500: liquid crystal display device

600: display unit 610: liquid crystal display panel

612: first substrate 614: second substrate

620: driving chip 630: flexible circuit board

The present invention relates to a backlight assembly and a liquid crystal display having the same, and more particularly, to a backlight assembly having a light guide plate having improved appearance characteristics and a reduced overall thickness, and a liquid crystal display having the same.

In general, a liquid crystal display is a flat panel display that displays an image using liquid crystal, and is thinner and lighter than other display devices, and has a low driving voltage and low power consumption. This has been widely used throughout the industry.

Since the liquid crystal display device is a non-light emitting device in which the liquid crystal display panel displaying an image does not emit light by itself, a backlight assembly for supplying light to the liquid crystal display panel is provided.

The backlight assembly used in small and medium products such as mobile communication terminals uses a small light emitting diode as a light source due to the characteristics of the product. The light emitting diode has a form of a point light source having a relatively small light emitting portion. As such, the backlight assembly using the light emitting diode as a light source requires a light guide plate for converting light in the form of a point light source into light in the form of a surface light source.

The light guide plate includes patterns formed on a lower surface of the light guide plate in order to diffusely reflect incident light in the form of a point light source and change the light into a surface light source. The patterns may be formed in a printing or non-printing manner, or alternatively, may be formed of protrusions having a predetermined height.

The lower surface of the light guide plate has a flat surface except for a region where patterns are formed. Thus, the properties of the light exiting from the light guide plate depend entirely on the patterns formed on the bottom surface.

However, when the pattern formed on the lower surface of the light guide plate is a low height pattern, a problem of adsorption between the light guide plate and the reflective sheet occurs, and when the height of the pattern is too high, a problem arises in that the overall thickness of the light guide plate is increased.

Accordingly, the present invention has been made in view of such a problem, and the present invention provides a backlight assembly having a light guide plate capable of improving optical characteristics and having reduced overall thickness.

In addition, the present invention provides a liquid crystal display device having the above-described backlight assembly.

The backlight assembly according to one aspect of the present invention includes a light source and a light guide plate for generating light. The light guide plate includes an incident surface receiving light from the light source, an output surface vertically extending from one side of the incident surface, and a reflective surface extending from the other side of the incident surface to face the output surface. The reflective surface is provided with a plurality of protrusions and line-shaped fine concavo-convex patterns protruding at a predetermined height.

A liquid crystal display according to an aspect of the present invention includes a backlight assembly and a liquid crystal display panel. The backlight assembly may include a light source for generating light and an incident surface for receiving light from the light source, an exit surface vertically extending from one side of the incident surface, and an other side of the incident surface so as to face the exit surface. And a light guide plate having a reflective surface. The reflective surface is provided with a plurality of protrusions and line-shaped fine concavo-convex pattern protruding to a predetermined height.

According to the backlight assembly and the liquid crystal display having the same, a projection pattern and a fine uneven pattern are formed on the reflective surface of the light guide plate to improve luminance. In addition, by appropriately forming the height of the projections, it is possible to prevent the adsorption phenomenon between the light guide plate and the reflective sheet generated when the height of the projections is small and increase in the thickness of the light guide plate that occurs when the height of the projections is high.

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

1 is an exploded perspective view illustrating a backlight assembly according to an exemplary embodiment of the present invention, FIG. 2 is a perspective view illustrating a rear surface of the light guide plate illustrated in FIG. 1, and FIG. 3 is an enlarged enlarged view of a portion of the patterns illustrated in FIG. 2. It is also.

1 to 3, the backlight assembly 100 according to an embodiment of the present invention includes a light source 200 for generating light and a light guide plate 300 for guiding light generated from the light source 200. .

The light source 200 is disposed on one side of the light guide plate 300, that is, the incident surface 310 to generate white light. For example, the light source 200 may be provided with at least one light emitting diode. Since the light emitting diodes emit light within a predetermined angle range, a plurality of light emitting diodes are provided to correspond to the size of the light guide plate 300 so as to uniformly inject light into the incident surface 310 of the light guide plate 300.

The light guide plate 300 guides a traveling path of the light incident from the light source 200, and changes the light in the form of a point light source into light in a plane light source state. The light guide plate 300 is formed of a transparent material to minimize the loss of light. For example, the light guide plate 300 is made of polymethyl methacrylate (PMMA). On the contrary, the light guide plate 300 may be made of a polycarbonate (PC) material having better heat resistance than the PMMA material.

The light guide plate 300 includes an entrance surface 310 facing the light source 200, an exit surface 330 extending vertically from one side of the entrance surface 310, and an entrance surface 310 to face the exit surface 330. It includes a reflective surface 320 extending from the other side of.

The reflective surface 320 is provided with a plurality of protrusions 324 protruding at a predetermined height and a line-shaped fine uneven pattern 322 for scattering reflection of light.

Light incident from the light source 200 into the light guide plate 300 is scattered and reflected by the protrusions 324 and the fine concavo-convex pattern 322, and light that exceeds a specific critical angle determined by the material of the light guide plate 300 is reflected. The light exits through the exit surface 330 of the light guide plate 300.

The projections 324 are formed denser as the distance from the incident surface 310 to uniformly emit light incident from the incident surface 310 to the exit surface 330. Specifically, the luminance is good because the light path is short because the light path is short because the light path is short. Therefore, the protrusions 324 are formed less in the vicinity of the incident surface 310, so that the amount of light that is scattered and reflected by the protrusions 324 and exits to the exit surface 330 is adjusted. On the other hand, the farther away from the incident surface 310, the more scattered and reflected light is lost, and the longer the movement path of the light, the lower the luminance. Therefore, as the distance from the incident surface 310, the projections 324 are densely formed, thereby controlling the amount of light emitted to the exit surface 330. As a result, the projections 324 are formed denser as they move away from the incident surface 310, thereby making the luminance of light emitted to the exit surface 330 uniform.

The protrusions 324 have a height of about 5 μm to 10 μm. Preferably, the protrusions 324 have a height of about 6 μm to 7 μm. Since the protrusions 324 have a height within the above range, it is possible to prevent a problem of adsorption between the light guide plate 300 and the reflective sheet 410 that occur when the height of the protrusions 324 is low. In addition, an increase in thickness of the light guide plate 300 generated when the height of the protrusions 324 is high may be prevented.

The protrusions 324 have a conical shape. Alternatively, the protrusions 324 may have various shapes such as a cylindrical shape and a square pyramid shape.

The fine concave-convex pattern 322 is formed together with the protrusions 324 on the reflective surface 320 and has a line shape. The height and depth of the fine concave-convex pattern 322 are randomly formed over the entire area.

The fine concave-convex pattern 322 scatters and reflects light by assisting a reflection pattern formed of the protrusions 324. Accordingly, the light guide plate 300 having the reflective pattern in which the fine concavo-convex pattern 322 and the protrusions 324 are formed together is improved in brightness compared to the light guide plate 300 having the reflective pattern consisting of the protrusions 324 only.

The fine uneven pattern 322 is formed in a line shape parallel to the incident surface 310. Alternatively, the fine uneven pattern 322 may be formed in a direction perpendicular to the incident surface 310.

The fine concave-convex pattern 322 is formed more densely away from the incident surface 310 in order to uniformly emit light incident from the incident surface 310 to the exit surface 330. Specifically, the luminance is good because the light path is short because the light path is short because the light path is short. Therefore, the minute uneven pattern 322 is formed in the vicinity of the incident surface 310 so that the period of unevenness is long. On the other hand, the farther away from the incident surface 310, the more scattered and reflected light is lost, and the longer the movement path of the light, the lower the luminance. Therefore, as the distance from the incident surface 310, the fine uneven pattern 322 is formed denser. As a result, the fine concave-convex pattern 322 is formed denser as it moves away from the incident surface 310, thereby making the luminance of light uniform throughout the emission surface 330. In contrast, the fine uneven pattern 322 may be formed in a uniform distribution over the entire area of the reflective surface 320.

Meanwhile, the backlight assembly 100 includes a reflection sheet 410 disposed on the reflective surface 320 of the light guide plate 300, a diffusion sheet 420 and a diffusion sheet disposed on the exit surface 330 of the light guide plate 300. It further includes a brightness enhancement sheet 430 disposed on the top of the (420).

The reflective sheet 410 reflects the light leaking to the outside through the reflective surface 320 of the light guide plate 300 to the inside of the light guide plate 300 to prevent the light leakage. The reflective sheet 410 is made of a material having high light reflectance. For example, the reflective sheet 410 is made of white polyethylene terephthalate (PET) or PC material.

The diffusion sheet 420 is disposed on the exit surface 320 of the light guide plate 300. The diffusion sheet 420 diffuses the light emitted from the exit surface 330 of the light guide plate 300 to improve luminance uniformity.

The luminance enhancing sheet 430 improves luminance characteristics by changing a propagation path of light passing through the diffusion sheet 420. The luminance enhancing sheet 430 may include at least one prism sheet for focusing light passing through the diffusion sheet 420 in a front direction.

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

Referring to FIG. 4, the liquid crystal display 500 according to an exemplary embodiment of the present invention may include a backlight unit 100 for supplying light and a display unit for displaying an image using light supplied from the backlight assembly 100. 600).

The backlight assembly 100 has the same configuration as the embodiment shown in FIGS. 1 to 3. Therefore, the same reference numerals are used for the same components, and redundant description thereof will be omitted.

The display unit 600 includes a liquid crystal display panel 610 for displaying an image, a driving chip 620 for driving the liquid crystal display panel 610, and a flexible circuit board for supplying various control signals to the liquid crystal display panel 610. 630.

The liquid crystal display panel 610 includes a first substrate 612, a second substrate 614 coupled to the first substrate 612, and a liquid crystal interposed between the first substrate 612 and the second substrate 614. Layer (not shown).

The first substrate 612 is a transparent glass substrate in which thin film transistors (hereinafter referred to as TFTs) to which pixel electrodes are connected are formed in a matrix form. The second substrate 614 is a glass substrate in which RGB pixels for color are formed by a thin film process, and a common electrode made of a transparent conductive material is formed.

In the liquid crystal display panel 610 having the above configuration, when power is applied to the TFT, an electric field is formed between the pixel electrode and the common electrode, and the electric field is formed between the first substrate 612 and the second substrate 614. The arrangement of the liquid crystal molecules of the interposed liquid crystal layer is changed, and the transmittance of light is changed according to the arrangement change of the liquid crystal molecules to display a desired image.

The driving chip 620 is formed on the first substrate 612. The driving chip 620 generates a driving signal for driving the liquid crystal display panel 610 in response to various control signals applied through the flexible circuit board 630. The driving signal generated from the driving chip 620 is applied to the first substrate 612 to drive the liquid crystal display panel 610.

The flexible circuit board 630 is connected to one side of the first substrate 612 on which the driving chip 620 is mounted. The flexible circuit board 630 includes a driving circuit unit (not shown) for generating a control signal for controlling the driving of the liquid crystal display panel 610. The flexible circuit board 630 is electrically connected to the first substrate 612 by, for example, an anisotropic conductive film (ACF).

According to such a backlight assembly and a liquid crystal display having the same, a projection pattern and a fine uneven pattern are formed on the reflective surface of the light guide plate, thereby improving luminance. In addition, by appropriately forming the height of the projections, it is possible to prevent the adsorption phenomenon between the light guide plate and the reflective sheet generated when the height of the projections is small and increase in the thickness of the light guide plate that occurs when the height of the projections is high.

In the detailed description of the present invention described above with reference to the preferred embodiments of the present invention, those skilled in the art or those skilled in the art having ordinary skill in the art will be described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (9)

A light source for generating light; And And a light guide plate having an incident surface receiving light from the light source, an emitting surface vertically extending from one side of the incident surface, and a reflective surface extending from the other side of the incident surface so as to face the emitting surface. And a plurality of protrusions and a line-shaped fine uneven pattern formed on the reflective surface. The backlight assembly of claim 1, wherein the fine uneven pattern is formed in a direction parallel to the incident surface. The backlight assembly of claim 2, wherein the fine concavo-convex pattern is formed densely away from the incident surface. The backlight assembly of claim 1, wherein the protrusions have a conical shape. The backlight assembly of claim 4, wherein the protrusions are densely formed away from the incident surface. The backlight assembly of claim 4, wherein the protrusions have a height of about 5 μm to about 10 μm. A light source for generating light, an incident surface receiving light from the light source, an exit surface vertically extending from one side of the incident surface, and a reflection surface extending from the other side of the incident surface so as to face the exit surface; A backlight assembly including a light guide plate provided thereon; And A liquid crystal display panel displaying an image using light from the backlight assembly; And a plurality of protrusions and a line-shaped fine uneven pattern formed on the reflective surface. The liquid crystal display device according to claim 7, wherein the fine uneven pattern is formed in a direction parallel to the incident surface. The liquid crystal display of claim 7, wherein the protrusions have a conical shape.

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