KR20130055204A - Backlight unit and liquid crystal display device - Google Patents

Abstract

PURPOSE: A backlight unit and a liquid crystal display are provided to minimize the thickness of an optical sheet by using a composite sheet. CONSTITUTION: A light guide plate is located in the upper part of a reflecting plate and includes an inclined first front surface. The light guide plate includes a first area having a first and a second thickness. An LED assembly faces one side corresponding to the first thickness. An optical sheet(121) consists of a diffusion sheet(121a) and a composite sheet(121b) formed in the upper part of the light guide plate. The composite sheet is formed by bonding the first to the second optical sheet(210,220).

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a liquid crystal display device, and more particularly to a thin liquid crystal display device capable of improving front luminance.

A liquid crystal display device (LCD), which is advantageous for moving picture display and has a large contrast ratio and is actively used in TVs and monitors, exhibits optical anisotropy and polarization properties of a liquid crystal, And the like.

Such a liquid crystal display is an essential component of a liquid crystal panel bonded through a liquid crystal layer between two side-by-side substrates, and realizes a difference in transmittance by changing an arrangement direction of liquid crystal molecules with an electric field in the liquid crystal panel. do.

However, since the liquid crystal panel does not have its own light emitting element, a separate light source is required in order to display the difference in transmittance as an image. To this end, a backlight unit in which a light source is embedded is disposed on the back of the liquid crystal panel.

Fluorescent lamps such as Cold Cathode Fluorescent Lamps (CCFLs) and External Electrode Fluorescent Lamps (EEFLs) have been used as the light source of the backlight unit. Recently, power consumption, weight, and luminance have been used. Light emitting diodes (LEDs), which have advantages in the back, are replacing fluorescent lamps.

According to the position of the light source, it can be divided into a direct type backlight unit and an edge type backlight unit. A direct backlight unit directly arranges light emitted from the light source by arranging the light source under the liquid crystal panel. The side panel backlight unit has a light guide plate disposed below the liquid crystal panel, and the light source is disposed on at least one side of the light guide plate to indirectly emit light emitted from the light source using the reflection and reflection of the light guide plate. It is a way to feed.

Such a backlight unit includes a plurality of optical sheets including a diffusion sheet and one or more prism sheets in order to improve the brightness of light emitted from the light source.

As such, by using a plurality of diffusion sheets and prism sheets overlapped with each other, high brightness can be realized, but the thickness of the liquid crystal display device is increased and the overall manufacturing cost is increased.

In particular, the liquid crystal display device has recently been increasingly used as a portable computer as well as desktop computer monitors and wall-mounted televisions, and is actively making efforts to implement lightweight and thin liquid crystal display devices. There are a lot of components constituting the liquid crystal display device has a problem that there is a limit in reducing the thickness.

An object of the present invention for solving the above problems is to provide a backlight unit and a liquid crystal display device that can improve the brightness while reducing the thickness.

Liquid crystal display device according to the present invention for achieving the above object is a liquid crystal panel; A light guide plate including a reflector plate, a first region positioned on the reflector plate, the first region increasing from a first thickness to a thicker second thickness including an inclined first surface, and a plurality of LEDs are mounted on the printed circuit board; And a plurality of optical sheets including a LED assembly positioned to face one side surface of the first region corresponding to the first thickness of the first region, and a plurality of optical sheets including a diffusion sheet and a composite sheet sequentially interposed over the light guide plate. And a backlight unit positioned on the rear surface of the composite sheet, wherein the first optical sheet and the second optical sheet are bonded to each other.

The light guide plate may include a second region connected to the first region and increasing from a first thickness to a third thicker thickness, including a second front surface having a slope in a direction different from that of the first front surface. The LED assembly is positioned to face the side corresponding to the third thickness of the second region.

In addition, the composite sheet includes an adhesive layer for bonding between the first optical sheet and the second optical sheet between the first optical sheet and the second optical sheet, the adhesive layer has a refractive index of the range of 1.45 to 1.5 Characterized in having a.

In addition, the inclination angle of the first front surface of the light guide plate depends on the light exit direction from the composite sheet, and is characterized in that less than 10 degrees with respect to the rear surface of the light guide plate.

On the other hand, the backlight unit according to a preferred embodiment of the present invention, the reflection plate; A light guide plate positioned on an upper portion of the reflective plate and including a first region which increases from a first thickness to a second thicker thickness including an inclined first front surface; A plurality of LEDs mounted on the printed circuit board and positioned to face one side surface corresponding to the first thickness of the first region; And a plurality of optical sheets including a diffusion sheet and a composite sheet sequentially interposed above the light guide plate, wherein the composite sheet is in a state in which the first optical sheet and the second optical sheet are bonded to each other.

As described above, according to the present invention, a thin liquid crystal display device can be realized by minimizing the thickness of the optical sheet by applying a composite sheet in which two optical sheets are bonded.

In addition, the reduction of the front luminance generated by applying the composite sheet is characterized by solving the front slope of the light guide plate.

By applying the composite sheet and modifying the structure of the light guide plate as described above, it is possible to realize a thin liquid crystal display device while reducing component cost and to improve front luminance.

1 is an exploded perspective view showing a liquid crystal display according to a first embodiment of the present invention.
2 is a cross-sectional view showing a liquid crystal display device according to a first preferred embodiment of the present invention.
3 is a cross-sectional view illustrating in detail a plurality of optical sheets of FIGS. 1 and 2;
4 is a view for explaining a light output direction in the liquid crystal display according to the first embodiment of the present invention.
5 is a graph illustrating the light exit angle in the plurality of optical sheets according to the present invention.
6 is an exploded perspective view showing a liquid crystal display according to a second preferred embodiment of the present invention.
7 is a cross-sectional view showing a liquid crystal display device according to a second preferred embodiment of the present invention.
8 is a perspective view showing in detail a light guide plate according to a second embodiment of the present invention.
9 is a view for explaining a light output direction in the liquid crystal display according to the second embodiment of the present invention.

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

1 is an exploded perspective view showing a liquid crystal display device according to a first embodiment of the present invention, Figure 2 is a cross-sectional view showing a liquid crystal display device according to a first embodiment of the present invention.

As shown in FIG. 1 and FIG. 2, the liquid crystal display device 100 includes a liquid crystal panel 110, a backlight unit 120, and a support main for modularizing the liquid crystal panel 110 and the backlight unit 120. 130 and the cover bottom 150, the top cover 140.

The liquid crystal panel 110 is a part that plays a key role in image display and is composed of a first substrate 112 and a second substrate 114 which are bonded to each other with a liquid crystal layer interposed therebetween.

Although not shown in the drawings, a plurality of gate lines and data lines intersect on the inner surface of the first substrate 112, which is commonly referred to as a lower substrate or an array substrate, under the premise of an active matrix scheme, and pixels are defined at each intersection. A thin film transistor (TFT) is provided to correspond one-to-one with a transparent pixel electrode formed in each pixel.

In addition, the inner surface of the second substrate 114 called the upper substrate or the color substrate may correspond to each pixel, for example, a color filter of red (R), green (G), and blue (B) color; Each of them is provided with a black matrix covering non-display elements such as gate lines, data lines, and thin film transistors, and transparent common electrodes covering them. Here, the transparent common electrode may be formed on the first substrate 112.

First and second polarizing plates 119a and 119b for selectively transmitting only specific light are attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

In addition, the printed circuit board 117 is connected through at least one edge of the liquid crystal panel 110 through a connection member 116 such as a flexible circuit board or a tape carrier package (TCP). In the support main 130 side or cover cover 150 may be properly folded to be in close contact with the back.

Accordingly, the liquid crystal panel 110 having the above-described structure may be configured to have a data driving circuit when the thin film transistor selected for each gate line is turned on by an on or off signal of a gate driver circuit transmitted through the printed circuit board 117. The signal voltage is transmitted to the corresponding pixel electrode through the data line, and the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, thereby indicating a difference in transmittance.

On the rear surface of the liquid crystal panel 110, a backlight unit 120 is provided to supply light so that the difference in transmittance can be displayed as an image.

The backlight unit 120 includes a light source arranged along an edge of the support main 130, a reflector 125, a light guide plate 123 seated on the reflector 125, and a plurality of optical sheets interposed thereon. (121).

As a light source, a fluorescent lamp or an LED 129a may be used. When the LED 129a is used, each of the plurality of LEDs 129a is spaced at a predetermined interval and mounted on a printed circuit board (PCB) 129b. Thereby forming the LED assembly 129.

In this case, each of the plurality of LEDs 129a may correspond to a side-view type that emits light to one side, and the printed circuit board 129b has a flexible property. Circuit Board: FPCB).

The light guide plate 123 evenly spreads the light incident from each of the plurality of LEDs 129a to a wide area of the light guide plate 123 while propagating through the light guide plate 123 by a plurality of total reflections to provide a surface light source to the liquid crystal panel 110. Be sure to

The light guide plate 123 includes a first region and a second region 123a and 123b. In this case, one end of the printed circuit board 129b may extend to cover a portion of the first region 123a of the light guide plate 123 or a portion of the second region 123b including the first region 123a. have.

Here, the first region 123a includes a first front surface 123a1 inclined and has a wedge shape that decreases from the first thickness h1 to the second thickness h2, and the second region 123b. Is connected to the first region 123a and has a square plate shape having a second thickness h2.

Here, the first region 123a is a region for receiving light from the light source and has a first length l1, and the second region 123b is a region for interposing the plurality of optical sheets 121. It is formed in a second length (l2) longer than one length (l1).

Accordingly, the position of the LED assembly 129 is fixed to face the side of the first region 123a of the light guide plate 123 so that the light emitted from the plurality of LEDs 129a may pass through the side of the first region 123a. Incident.

That is, the first region 123a serves to guide the light emitted from each of the plurality of LEDs 129a to be incident into the light guide plate 123 without loss.

In addition, the second region 123b serves to reduce the overall thickness of the liquid crystal display 100 by allowing the plurality of optical sheets 121 to be sequentially disposed on the second front surface 123b1. Through this, a thin liquid crystal display device can be realized.

As such, the light guide plate 123 is composed of the first and second regions 123a and 123b, and thus the light guide plate 123 may be manufactured by injection molding used to mold a specific shape because the thickness is not constant.

In addition, the light guide plate 123 may include a pattern of a specific shape on the rear surface to supply a uniform surface light source. The pattern may be configured in various ways such as an elliptical pattern, a polygonal pattern, a hologram pattern, and the like to guide light incident to the inside of the light guide plate 123. The back surface of the light guide plate 123 may be formed by a printing method or an injection method.

The reflective plate 125 is positioned on the rear surface of the light guide plate 123. The reflective plate 125 reflects the light passing through the rear surface of the light guide plate 123 toward the liquid crystal panel 110 to improve the brightness of the light.

In addition, the plurality of optical sheets 121 sequentially disposed on the second front surface 123b1 of the second region 123b of the light guide plate 123 diffuse or condense the light converted into the surface light source by the light guide plate 123. A more uniform surface light source is incident on the liquid crystal panel 110.

The plurality of optical sheets 121 may include a diffusion sheet 121a for diffusing light and a composite sheet 121b for diffusing and condensing light.

Here, the composite sheet 121b is a sheet in which at least two optical sheets are laminated to reduce the overall thickness of the plurality of optical sheets 121 and further reduce the overall thickness of the liquid crystal display device 100. It is done. This will be described later in detail.

The liquid crystal panel 110 and the backlight unit 120 described above are modularized through the top cover 140, the support main 130, and the cover bottom 150.

More specifically, the liquid crystal panel 110 and the backlight unit 120 are covered with a top cover 140 that covers the top edge of the liquid crystal panel 110 in a state where the liquid crystal panel 110 and the backlight unit 120 are surrounded by a support main body 130 having a rectangular- The cover bottoms 150 covering the back surface of the main body 120 are coupled to each other at the front and rear sides,

As it is modularized, the light emitted from each of the plurality of LEDs 129a of the backlight unit 120 is incident on the light incident surface of the light guide plate 123 and then refracted toward the liquid crystal panel 110 therein, and the reflecting plate While passing through the plurality of optical sheets 121 together with the light reflected by the 125 is processed into a more uniform high-quality surface light source is supplied to the liquid crystal panel 110.

Meanwhile, the light shielding tape 160 may be positioned between the LED printed circuit board 129b of the backlight unit 120 and the liquid crystal panel 110 in the modularization process, and the light shielding tape 160 may be the liquid crystal panel 110. It may serve to prevent light from leaking to an area other than the display area of.

In addition, the top cover 140 in the liquid crystal display device module 100 may also be referred to as a case top or a top case, and the support main 130 may be referred to as a guide panel, a main support, or a mold frame. ) Is also called bottom cover.

Hereinafter, a plurality of optical sheets included in the above-described liquid crystal display and an emission direction of light emitted therefrom will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view illustrating a plurality of optical sheets of FIGS. 1 and 2, FIG. 4 is a view for explaining a light output direction in a liquid crystal display according to a preferred embodiment of the present invention, and FIG. As a graph for explaining the light exit angle in the plurality of optical sheets according to, refer to FIGS. 1 and 2.

As shown in FIG. 3, the plurality of optical sheets 121 includes a diffusion sheet 121a and a composite sheet 121b interposed therebetween, and the composite sheet 121b has a double structure.

Here, the diffusion sheet 121a includes a support layer 201 as a base, a light diffusion layer 203 formed on the support layer 201, and a back layer 205 formed under the support layer 201.

The support layer 201 is most preferably made of polyethylene terephthalate (PET), but is not limited thereto. Polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI) ), Polyethyelenen napthalate (PEN), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose It may also consist of cellulose acetate propinonate (CAP).

The light diffusing layer 203 contains a plurality of first beads 204 having different sizes in the transparent binder resin to diffuse and diffuse light by refracting and scattering the incident light, and the non-uniformity passed through the light guide plate (123 in FIG. 1). It serves to emit light as uniform light.

As the binder resin, an acrylic resin, a urethane resin, an epoxy resin, a vinyl resin, a polyester resin, a polyamide resin, or the like can be used as the binder resin because of high transparency and excellent light transmittance and easy viscosity control.

The back layer 205 improves the adhesion between the substrate positioned under the diffusion sheet 121a, that is, the light guide plate 123 of FIGS. 1 and 2, so that the diffusion sheet 121a and the light guide plate 123 of FIG. It prevents appearance defects due to wet-out phenomenon that may be caused by sticking and moire patterns that may occur on the display screen.

The back layer 205 is a coating layer in which a plurality of uniform second beads 206 having a diameter in the range of 3 μm to 5 μm is dispersed and contains an auxiliary role of diffusing light through the plurality of second beads 206. You can also do In this case, the plurality of second beads 206 may be contained at a smaller ratio than the plurality of first beads 204 included in the light diffusion layer 203.

The composite sheet 121b interposed on the diffusion sheet 121a having the above configuration has a form of a composite sheet in which the first optical sheet 210 and the second optical sheet 220 are bonded to each other.

More specifically, the first optical sheet 210 including the first optical layer 213 and the first optical layer 213 formed on the first support layer 211 and the second support layer 221 and the second support layer ( The second optical sheet 220 including the second optical layer 223 formed on the upper portion 221 is bonded to each other through the adhesive layer 230 to form the composite sheet 121b.

Most preferably, the first and second support layers 211 and 221 are made of polyethylene terephthalate (PET), but are not limited thereto. Polyethersulphone (PES), polyacrylate (PAR), Polyetherimide (PEI), polyethylenenaphthalate (polyethyelenen napthalate: PEN), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose Triacetate (TAC), cellulose acetate propionate (CAP), or the like. Although not shown in the drawings, since the first support layer 211 serves as a base for supporting the entire composite sheet 121b, the thickness of the second support layer 221 may be smaller than that of the first support layer 211. have. Through this, the overall thickness of the composite sheet 121b may be reduced.

The first and second optical layers 213 and 223 are layers for diffusing or condensing light, and may be photocurable resins, for example, acrylic resins, polyurethanes, and fluorine resins. ), Silicon resin, epoxy resin and the like.

In this case, the first optical layer 213 includes a plurality of prismatic patterns 216 for condensing light. The plurality of prism patterns 216 may be formed by repeating and arranging a triangular shape composed of a first inclined surface 214 and a second inclined surface 215 symmetrically to be arranged in a first direction. The peaks and valleys are repeated along the first direction by the plurality of prismatic patterns 216.

Here, the prism pattern 216 is applied as a light collecting pattern for condensing light by forming a triangular prism, but is not limited thereto, and pyramids, hemispheres, and cones as other light collecting patterns. It may be formed in a variety of patterns, including).

As illustrated in the drawing, the second optical layer 223 may be formed of a photocurable resin having a predetermined thickness.

Alternatively, like the first optical layer 213, the second optical layer 223 may include a plurality of prism patterns. In this case, the plurality of prism patterns formed in the first optical layer 213 and the plurality of prism patterns formed in the second optical layer 223 may be formed so that the longitudinal directions of each of the patterns cross each other or may be the same. .

Meanwhile, a back layer (not shown) may be formed on the rear surface of the first support layer 211 similarly to the diffusion sheet 121a. Such a back layer (not shown) may be generated in a wet-out phenomenon and a display screen, which may be caused by the sheets being adhered to each other by improving adhesion to the diffusion sheet 121a positioned below the composite sheet 121b. It may serve to prevent appearance defects due to moiré pattern.

The adhesive layer 230 serves to bond the first optical sheet 210 and the second optical sheet 220 to each other, and may have a refractive index in a range of 1.45 to 1.5.

As such, by applying the composite sheet 121b in which the first optical sheet 210 and the second optical sheet 220 are integrally formed, a plurality of optical sheets may be applied rather than applying the first optical sheet and the second optical sheet, respectively. The overall thickness of the 121 may be reduced, and further, the thin liquid crystal display device may be realized.

On the other hand, when the light of maximum intensity emitted from the liquid crystal display (hereinafter referred to as light) is emitted in a normal direction perpendicular to the emission surface of the liquid crystal display, the front luminance is maximized, and the emission angle of the light is usually It is called 0 degree.

Hereinafter, this will be described by applying to the present invention. Here, the front surface of the composite sheet from which light is emitted is called an exit surface.

Accordingly, the light emitted from the composite sheet 121b according to the present invention is inclined in the first angle θ1 in a positive direction with respect to a normal line perpendicular to the emission surface, thereby reducing front luminance.

Referring to FIG. 4, the first light a1 emitted from the second front surface 123b1 of the light guide plate 123 is emitted in a normal direction perpendicular to the second front surface 123b1.

The first light a1 passes through the diffusion sheet 121a and the composite sheet 121b and is not emitted as a second light a2 in the normal direction perpendicular to the exit surface of the composite sheet 121b. As (a3), there is a problem in that the front luminance is decreased by emitting in a state in which the first angle θ1 is inclined in a positive direction with respect to a normal line perpendicular to the emission surface.

In the related art, although an air layer having a refractive index of 1 exists between the first optical sheet and the second optical sheet as the first optical sheet and the second optical sheet are sequentially interposed, the composite sheet 121b according to the present invention is applied. As the adhesive layer 230 having a refractive index of 1.45 to 1.5 is positioned between the first optical sheet 210 and the second optical sheet 220, the refractive angle at which the light emitted from the first optical sheet 210 is refracted is conventional. This is because the air layer becomes smaller than when present.

More specifically, the light emitted from the light guide plate is generally spread as it passes through the diffusion sheet, and the emission angle of the light is about 54 degrees as illustrated in FIG. 5, and the first and second upper portions of the diffusion sheet are disposed. Through the optical sheet, the light's exit angle is close to the normal (0 degrees) perpendicular to the exit plane.

However, when the composite sheet 121b in which the first optical sheet 210 and the second optical sheet 220 are bonded to each other through the adhesive layer 230 is applied, the composite sheet as shown in FIG. 5. The exit angle of the light emitted from 121b becomes 11 degrees, and the front luminance decreases while being inclined much at 0 degrees (normal).

Accordingly, hereinafter, a liquid crystal display device capable of improving front luminance according to the second embodiment of the present invention will be described in detail.

6 is an exploded perspective view of a liquid crystal display device capable of improving front brightness according to a second embodiment of the present invention, and FIG. 7 is a liquid crystal display device of which front brightness can be improved according to a second embodiment of the present invention. 8 is a cross-sectional view illustrating a light guide plate according to a second embodiment of the present invention in detail. Here, since the configuration except for the light guide plate is the same as that of the liquid crystal display of FIGS. 1 and 2, the same reference numeral is assigned to the same configuration, and a detailed description thereof will be omitted.

As shown in FIGS. 6 and 7, the liquid crystal display device 300 includes a liquid crystal panel 110, a backlight unit 320, and a support main for modularizing the liquid crystal panel 110 and the backlight unit 120. 130 and the cover bottom 150, the top cover 140.

The backlight unit 320 includes a light source arranged along an edge of the support main 130, a reflector 125, a light guide plate 323 seated on the reflector 125, and a plurality of optical sheets interposed thereon. Field 121.

Here, the light guide plate 323 provides a surface light source to the liquid crystal panel 110, and simultaneously emits light emitted from the backlight 120 and further from the liquid crystal display device 300 in a normal direction with respect to the screen. It is characterized by the role of correcting the direction.

The light guide plate 323 for this purpose includes a first area 323a1 having an inclined first front surface 323a1 and decreasing from the first thickness H1 to a thinner second thickness H2 as shown in FIG. 8. And a second area 323b connected to the first area 323a1 and having an inclined second front surface 323b1 and increasing from the second thickness H2 to a third thickness H3 thicker than this. Here, the third thickness H3 is preferably a thickness thinner than the first thickness H1, but is not limited thereto. The first thickness H3 may be the first thickness depending on the size of the light guide plate 323 and the emission direction of the light emitted from the composite sheet 121b. It may be the same thickness as (H1) or may be thicker than the first thickness (H1).

Accordingly, the front surface of the light guide plate 323 has a slope in different directions.

The first region 323a of the light guide plate 323 is a region for receiving light from the light source and is formed at a first length L1, and the second region 323b is used to adjust the light emission direction while implementing a surface light source. The region is formed with a second length L2 longer than the first length L1.

In particular, the inclination angle α of the second front surface 323b1 of the second region 323b may vary depending on the size of the light guide plate 323 and the emission direction of the light emitted from the plurality of optical sheets 121, but most preferably, It may be set to less than 10 degrees with respect to the back surface of the light guide plate 323.

Accordingly, the emission direction of the light emitted from the second front surface 323b1 of the light guide plate 323 is inclined at a first angle in a negative direction with respect to a normal line perpendicular to the screen (or the exit surface of the composite sheet 121b).

As a result, the light emitted from the light guide plate 323 passes through the composite sheet 121b of the plurality of optical sheets 121 and the emission direction of the light emitted from the composite sheet 121b may be a normal direction perpendicular to the emission surface. Will be. This will be described later in more detail.

On the other hand, since the light guide plate 323 is composed of the first and second regions 323a and 323b and the thickness is not constant, the light guide plate 323 may be manufactured by injection molding used to mold a specific shape.

In addition, the light guide plate 323 may include a pattern of a specific shape on the rear surface to supply a uniform surface light source. The pattern may be configured in various ways, such as an elliptical pattern, a polygonal pattern, a hologram pattern, and the like to guide the light incident into the light guide plate 323. The back surface of the light guide plate 323 may be formed by a printing method or an injection method.

An optical path in such a light guide plate and a plurality of optical sheets will be described with reference to the drawings.

9 is a view illustrating a light exit direction in the light guide plate and the plurality of optical sheets according to the second embodiment of the present invention. Referring to FIGS. 6 to 8.

As shown in FIG. 9, the first light A1 emitted through the second front surface 323b1 of the second region 323b of the light guide plate 323 is emitted in a normal direction perpendicular to the second front surface 323b1. As the second front surface 323b1 is formed to be inclined with respect to the rear surface, the first light A1 is inclined in the negative direction with respect to the normal A perpendicular to the rear surface. do.

The first light A1 is emitted as the second light A2 while passing through the diffusion sheet 121a and the composite sheet 121b which are the plurality of optical sheets 121.

In this case, the composite sheet 121b is configured to allow the light emitted through the exit surface thereof to be inclined in the first angle α in a positive direction with respect to a normal line perpendicular to the exit surface, so that the second light A2 is disposed on the exit surface. Can be emitted in a normal direction perpendicular to the

As described above, according to the present invention, a light guide plate 323 having an inclined front surface for adjusting the light emission direction is applied to a normal line perpendicular to the rear surface of the light guide plate 323 by applying the light guide plate 323. The output direction of the light emitted from the plurality of optical sheets 121 may be a normal line direction perpendicular to the emission surface by correcting the emission direction of the light in advance so as to have the first angle in the negative direction. This makes it possible to maximize the front brightness.

In other words, when a thin liquid crystal display device is implemented by applying a composite sheet having a form in which the first and second optical sheets are bonded together, the front luminance may also be improved.

On the other hand, as another embodiment of the light guide plate, it is preferable that the present invention can also be applied to a light guide plate including only the second region in which the wedge-shaped first region is deleted.

The embodiments of the present invention as described above are merely illustrative, and those skilled in the art can make modifications without departing from the gist of the present invention. Accordingly, the protection scope of the present invention includes modifications of the present invention within the scope of the appended claims and equivalents thereof.

100 and 300: liquid crystal display 110: liquid crystal panel
120, 320: backlight unit 121: a plurality of optical sheets
121a: diffusion sheet 121b: composite sheet
210: first optical sheet 220: second optical sheet
123, 323: LGP 125: Reflector
129: LED assembly

Claims (8)

A liquid crystal panel;
A light guide plate including a reflector plate, a first region positioned on the reflector plate, the first region increasing from a first thickness to a thicker second thickness including an inclined first surface, and a plurality of LEDs are mounted on the printed circuit board; And a plurality of optical sheets including a LED assembly positioned to face one side surface of the first region corresponding to the first thickness of the first region, and a plurality of optical sheets including a diffusion sheet and a composite sheet sequentially interposed over the light guide plate. It includes a backlight unit located on the back of,
The composite sheet
A liquid crystal display device in which a first optical sheet and a second optical sheet are bonded to each other.
The method of claim 1,
The light-
A second region connected to the first region and increasing from a first thickness to a third thicker thickness, including a second front surface having a slope in a direction different from that of the first front surface;
The LED assembly
And a side surface of the second region facing the side surface corresponding to the third thickness.
The method of claim 1,
The composite sheet
An adhesive layer for bonding between the first optical sheet and the second optical sheet between the first optical sheet and the second optical sheet,
The adhesive layer is
A liquid crystal display device having a refractive index in the range of 1.45 to 1.5.
The method of claim 1,
The inclination angle of the first front surface of the light guide plate is
The liquid crystal display device according to the direction of the light output from the composite sheet, characterized in that less than 10 degrees with respect to the back surface of the light guide plate.
A reflector;
A light guide plate positioned on an upper portion of the reflective plate and including a first region which increases from a first thickness to a second thicker thickness including an inclined first front surface;
A plurality of LEDs mounted on the printed circuit board and positioned to face one side surface corresponding to the first thickness of the first region;
Comprising a plurality of optical sheets consisting of a diffusion sheet and a composite sheet sequentially interposed above the light guide plate,
The composite sheet
The backlight unit in a state where the first optical sheet and the second optical sheet are bonded.
6. The method of claim 5,
The light-
A second region connected to the first region and increasing from a first thickness to a third thicker thickness, including a second front surface having a slope in a direction different from that of the first front surface;
The LED assembly
And a side surface of the second region facing the side surface corresponding to the third thickness.
6. The method of claim 5,
The composite sheet
An adhesive layer for bonding between the first optical sheet and the second optical sheet between the first optical sheet and the second optical sheet,
The adhesive layer is
And a refractive index has a range of 1.45 to 1.5.
6. The method of claim 5,
The inclination angle of the first front surface of the light guide plate is
It depends on the light output direction from the composite sheet, the backlight unit, characterized in that less than 10 degrees with respect to the back surface of the light guide plate.

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