KR101858249B1 - Backlight Unit and Liquid Crystal Display Device having the same - Google Patents

Abstract

The present invention discloses a backlight unit and a liquid crystal display device. In the disclosed backlight unit, the backlight unit of the present invention includes a light source for generating light, a first optical sheet and a second optical sheet for condensing and diffusing the light source, and a light guide plate for converting light generated from the light source into a surface light source A plurality of dot patterns are formed on a lower surface of the light guide plate, and a plurality of optical patterns are formed in the dot pattern.
The backlight unit of the present invention has an effect of improving the brightness and reducing the number of optical sheets by changing the structure of the dot pattern formed on the light guide plate.

Description

BACKLIT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE Having the same

The present invention relates to a backlight unit of a liquid crystal display.

A liquid crystal display (LCD) is one of flat panel displays for displaying images using a liquid crystal, and is thin and light compared to other display devices, and has advantages of low power consumption, .

Such a liquid crystal display device comprises a liquid crystal display panel for displaying an image and a backlight unit for supplying light to the liquid crystal display panel.

The liquid crystal display device is classified into an edge type and a direct type according to the arrangement of the light sources. The edge type backlight unit is provided with a light guide plate on the back surface of the liquid crystal display panel, and a light source is disposed on the side of the light guide plate to supply the surface light source to the liquid crystal display panel. The direct-type backlight unit is applied to a large-sized liquid crystal display device of 12 inches or more, and a plurality of light sources are disposed on the back surface of the liquid crystal display panel, and the light emitted from the plurality of light sources is supplied to the front liquid crystal display panel.

As the light source of the backlight unit, EL (Electro Luminescence), Cold Cathode Fluorescent Lamp (CCFL), Hot Cathode Fluorescent Lamp (HCFL), and LED are used. Recently, a light emitting diode having excellent light efficiency and high color reproduction rate is used as a light source of a backlight unit. The light source may be a package light source composed of red, green, and blue light emitting diodes, or a white light emitting diode light source.

In addition, a plurality of dot patterns are formed on the lower surface of the light guide plate of the backlight unit. However, there is a problem that it is difficult to obtain outgoing light perpendicular to the liquid crystal display panel direction only by the dot pattern.

Therefore, a plurality of prism sheets and diffusion plates (optical sheets) are used to change the light emitted from the light guide plate in the vertical direction.

However, if the number of optical sheets of the backlight unit is increased, the manufacturing cost is increased and the thickness of the liquid crystal display device is increased.

Therefore, there is a demand for a technique capable of improving the required luminance condition and viewing angle characteristic while reducing the number of optical sheets in the liquid crystal display device.

An object of the present invention is to provide a backlight unit and a liquid crystal display device having the backlight unit which can improve the brightness and the number of optical sheets by changing the structure of the dot pattern formed on the light guide plate of the backlight unit.

Another object of the present invention is to provide a backlight unit in which the structure of a dot pattern formed on a light guide plate of a backlight unit is modified to improve viewing angle characteristics of emitted light and a liquid crystal display device having the backlight unit.

Another object of the present invention is to provide a backlight unit and a liquid crystal display device having the backlight unit, which can improve brightness, viewing angle, and productivity by forming various types of optical patterns in a dot pattern formed on a light guide plate of a backlight unit.

According to an aspect of the present invention, there is provided a backlight unit including a light source for generating light, a first optical sheet and a second optical sheet for condensing and diffusing the light source, A plurality of dot patterns are formed on a lower surface of the light guide plate, and a plurality of optical patterns are formed in the dot pattern.

According to another aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal display panel; And a backlight unit for supplying light to the liquid crystal display panel, wherein the backlight unit includes: a light source for generating light; a first optical sheet and a second optical sheet for condensing and diffusing the light source; And a plurality of optical patterns are formed on the lower surface of the light guide plate, wherein the plurality of optical patterns are formed in the dot pattern.

The present invention has the effect of improving the brightness and reducing the number of optical sheets by changing the structure of the dot pattern formed on the light guide plate of the backlight unit.

Further, the present invention has an effect of improving the viewing angle characteristic of outgoing light by changing the structure of the dot pattern formed on the light guide plate of the backlight unit.

In addition, the present invention has the effect of improving the brightness, viewing angle, and productivity by forming various types of optical patterns in the dot pattern formed on the light guide plate of the backlight unit.

1 is an exploded perspective view of a liquid crystal display device according to a first embodiment of the present invention.
2 is a view showing a structure of a light guide plate according to a first embodiment of the present invention.
3 is a cross-sectional view taken along line I-I 'of FIG.
4A and 4B are diagrams showing emitted light characteristics according to the structure of the optical patterns in the dot pattern formed in the light guide plate of the first embodiment of the present invention.
5A to 5C are diagrams showing the shapes of various optical patterns formed in the dot pattern of the light guide plate of the present invention.
6 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention.
7 is a cross-sectional view taken along line II-II 'of FIG.
8A to 8E are views showing various structures of a light guide plate incorporated in a backlight unit of a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

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

2 is a view showing the structure of a light guide plate according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view of the light guide plate according to the first embodiment of the present invention, Sectional view taken along line I 'of FIG.

1 to 3, the liquid crystal display according to the first embodiment of the present invention includes a liquid crystal display panel 110 and a backlight unit 120 for providing a surface light source to the liquid crystal display panel 110 do.

The liquid crystal display panel 110 includes an upper substrate 110a including red (R) color filter layers, a lower substrate 110b including a thin film transistor (TFT) and a pixel electrode, As shown in Fig.

A gate driving circuit (not shown) for supplying a scan signal to the gate line and a data driving circuit (not shown) for supplying a data signal to the data line are provided at the edge of the liquid crystal display panel 110.

The gate and the data driving circuit are electrically connected to the liquid crystal display panel 110 by COF (chip on film). Here, the COF may be changed to a TCP (Tape Carrier Package).

The backlight unit 120 may include an LED chip 150 (hereinafter, referred to as an LED) 150 composed of red (R), green (G) and blue (B) color light emitting diodes (LEDs) A printed circuit board 151 on which a plurality of power supply patterns are formed to supply power to the LED chip 150 and a light guide plate 152 for converting the light source supplied from the LED chip 150 into a surface light source, A reflection plate 180 disposed on the back surface of the light guide plate 140 to improve light efficiency and a first and a second optical sheet 180 disposed on the upper side of the light guide plate 180 and functioning as a light- 131 and 132 and a lower cover 190 for receiving the LED chip 150, the printed circuit board 151, the light guide plate 140, the reflector 180, the first and second optical sheets 131 and 132, .

The first optical sheet 131 functions as a prism sheet for condensing the surface light source supplied from the light guide plate 140 and the second optical sheet 132 functions as a light guide plate 140 To the surface light source.

The liquid crystal display panel 110 and the backlight unit 120 are integrally coupled to each other while the support main 115 and the lower cover 190 are assembled.

A plurality of dot patterns 160 are formed on the lower surface of the light guide plate 140 of the backlight unit 120 of the present invention. The diameter of the dot pattern 160 may be the same or different. In the dot pattern 160, a plurality of optical patterns 161 are patterned at regular intervals. However, the density of the dot patterns 160 may be made small at the light-incoming portion of the light guide plate 140, and may be formed at a distance to the opposite side of the light-incoming portion.

The optical patterns 161 are formed in the shape of a continuous non-inverted rectangle (trapezoid), and the first slanted surface S1 and the second slanted surface S2, which are adjacent to each other in the plane section P of the optical patterns 161, May be formed to have the same length, but preferably have different lengths.

The first sloped surface S1 and the second sloped surface S2 of the optical pattern are arranged in a direction perpendicular to the proceeding light when the light generated from the LED chip 150 advances into the light guide plate 140 .

As shown in Fig. 3, the second inclined plane S2 of the optical pattern 161 is longer than the first inclined plane S1. In the present invention, the angle of a is formed in the range of 65 ° to 80 °, and the angle of b is formed in the range of 40 ° to 50 °. The height L2 of the optical pattern 161 is set in the range of 20 to 40 mu m and the pitch of the optical patterns 161 is set to 30 to 50 mu m. The length of the plane section P is formed in the range of 10 to 25 mu m.

The angle a refers to the angle of inclination of the first inclined surface with respect to the reference line after the reference line parallel to the lower surface of the light guide plate 140 is set at the vertex of the optical pattern 161 formed in the edge region of the first inclined surface. That is, the first inclined surface refers to an inclined advance angle (a and an angle) with respect to a plane section P parallel to the lower surface of the light guide plate 140 in the clockwise direction.

The angle b is an angle of inclination of the second inclined surface to the reference line after the reference line parallel to the lower surface of the light guide plate 140 is placed at the vertex of the optical pattern 161 formed in the edge region of the first inclined surface. That is, it means an inclined advance angle (b and a turning angle) in the counterclockwise direction of the second inclined plane with respect to the plane section P parallel to the lower side of the light guide plate 140.

4A and 4B are diagrams showing emitted light characteristics according to the structure of the optical patterns in the dot pattern formed in the light guide plate of the first embodiment of the present invention.

FIG. 4A shows a case where the cross-sectional structure of the optical patterns of the light guide plate of the present invention is a non-equal triangular structure, and FIG. 4B shows a case where the cross-sectional structure of the optical patterns has a non-trapezoidal trapezoidal structure.

3 to 4B, the light incident from the LED chip 150 into the light guide plate 140 is totally reflected in the light guide plate 140 and is reflected and refracted in the optical patterns 161 of the dot pattern 160. [ do. At this time, the first inclined plane S1 of the optical pattern 161 functions to adjust the angle of the totally reflected light to supply the second inclined plane S2. The second inclined plane S2 of the optical pattern 161 reflects the light reflected by the first inclined plane S1 and reflects the traveling light in a direction perpendicular to the upper surface of the light guide plate 140. [

As described above, the angle of the light emitted in the direction perpendicular to the light guide plate 140 is determined by the angles of a and b of the optical pattern 161. Therefore, when the design of the interval L1, angle a, b, height L2, and plane section P of the optical patterns 161 formed on the light guide plate 140 of the present invention is changed, It is possible to improve the angle and viewing angle of emitted light.

In particular, the plane section P formed between the optical patterns 161 is used to improve the viewing angle of the emitted light.

Comparing FIGS. 4A and 4B, there is a plane section P between optical patterns in FIG. 4B, and FIG. 4A does not have a plane section P between optical patterns. The viewing angle is remarkably improved in Fig. 4B than in Fig. 4A.

The density of the optical patterns 161 formed in the dot pattern 160 and the dot pattern 160 of the light guide plate 140 may be adjusted in order to ensure uniform luminance characteristics of the light emitted from the light guide plate 140. [

5A to 5C are diagrams showing the shapes of various optical patterns formed in the dot pattern of the light guide plate of the present invention.

3 and 5A to 5C, a planar section P is formed between the first inclined plane S1 and the second inclined plane S2 of the optical pattern 161 of the light guide plate 140, A rounded portion R1 having a predetermined curvature may be formed in the region where the first sloped surface S2 and the second sloped surface S2 meet.

5B, a curved surface R2 may be formed by removing the flat section where the optical pattern 161 is formed and rounding the entire surface. Alternatively, as shown in FIG. 5C, a flat section between the optical patterns 161 may be formed c). This can be applied in consideration of the viewing angle and luminance characteristics of the light emitted from the light guide plate 140.

As described above, according to the first embodiment of the present invention, various types of optical patterns are formed in the dot pattern formed on the light guide plate, thereby improving the brightness of light emitted from the light guide plate. In addition, the optical patterns formed on the light guide plate of the present invention can adjust the vertical direction of light emitted from the light guide plate. Thus, the optical sheet used for converting the light emitted from the light guide plate into the vertical light can be removed.

In addition, the first embodiment of the present invention can improve the viewing angle characteristic of light to be emitted by forming a plane section between optical patterns formed in the dot pattern of the light guide plate.

The second embodiment of the present invention described below can be implemented by applying the structure of the first embodiment of the present invention as described above, unless otherwise described. Therefore, the second embodiment of the present invention is also characterized in that the effects of the first embodiment of the present invention can be equally implemented.

FIG. 6 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 7 is a sectional view taken along line II-II 'of FIG.

6 and 7, the liquid crystal display according to the second embodiment of the present invention includes a liquid crystal display panel 210 and a backlight unit 220.

The liquid crystal display panel 210 includes an upper substrate 210a including red (R) color filter layers and a lower substrate 210b including a thin film transistor (TFT) As shown in Fig.

The backlight unit 220 includes an LED chip 250 composed of red (R), green (G) and blue (B) color light emitting diodes (LEDs) or white light emitting diodes A light guide plate 240 for converting a light source supplied from the LED chip 250 into a planar light source, a light guide plate 240 for guiding light from the light guide plate 240, A first and a second optical sheets 231 and 232 disposed on the upper side of the light guide plate 280 to function as a light collecting and diffusing device, And includes a chip 250, a printed circuit board 251, a light guide plate 240, a reflector 280, and a lower cover 290 for accommodating the first and second optical sheets 231 and 232.

The first optical sheet 231 functions as a prism sheet for condensing the surface light source supplied from the light guide plate 240 and the second optical sheet 232 functions as the light guide plate 240 To the surface light source.

The liquid crystal display panel 210 and the backlight unit 220 are integrally joined together while the support main body 215 and the lower cover 290 are assembled.

A plurality of dot patterns 260 are formed on the lower surface of the light guide plate 240 of the backlight unit 220 according to the second embodiment of the present invention. Concave and convex patterns 270 are formed at predetermined intervals.

The plurality of concavo-convex patterns 270 refract in the lower dot pattern 260 of the light guide plate 240 and refract the outgoing light proceeding in the vertical direction.

In addition, the plurality of concave-convex patterns 270 further diffuse the light reflected from the dot patterns 240 to have a uniform brightness characteristic over the entire area of the light guide plate 240.

The diameter of the dot pattern 260 may be the same or different. In the dot pattern 260, a plurality of optical patterns are patterned at regular intervals. Although not shown in the drawings, the present invention is implemented by applying the same structure of the dot pattern and the optical pattern described in the first embodiment of the present invention.

Therefore, the optical patterns formed in the dot pattern 260 formed on the lower side of the light guide plate of the second embodiment of the present invention and the optical patterns of the first embodiment of the present invention are the same as those of the first embodiment of the present invention, The design range (angle, plane section, height, slope length, etc.) is the same.

8A to 8E are views showing various structures of a light guide plate incorporated in a backlight unit according to a second embodiment of the present invention. Referring to FIGS. 8A to 8E, in the lower side of the light guide plate, A plurality of optical patterns are formed in the dot pattern and the dot pattern described above.

In addition, in the second embodiment of the present invention, a plurality of concave-convex patterns are formed on the upper surface of the light guide plate so as to correspond to the dot patterns formed on the lower side. The structure of the concavo-convex pattern may be formed of triangular, rectangular, polygonal, streamlined groove and convex lens cross-sections.

When the concavity and convexity pattern is formed into a triangular cross-sectional structure, it may be formed in an equilateral or non-triangular triangular structure. In the case of a rectangular (trapezoid) structure, the planar section may be formed in a straight line, a streamline shape, a concavo-convex shape, or the like.

As described above, in the second embodiment of the present invention, various patterns of optical patterns are formed in the dot pattern and the dot pattern on the lower side of the light guide plate, and a plurality of concave-convex patterns are formed on the upper side of the light guide plate, There is an effect of improving the luminance of light to be emitted.

In addition, the vertical direction of the light emitted from the light guide plate can be adjusted by changing the structure of the optical patterns and the concavo-convex pattern formed on the light guide plate of the present invention. Thus, an optical sheet such as a prism sheet can be removed.

In addition, the second embodiment of the present invention can improve the viewing angle characteristic of light emitted by forming a plane section between optical patterns formed in the dot pattern of the light guide plate.

110: liquid crystal display panel 120: backlight unit
115: Support main 150: LED chip
151: printed circuit board 131: first optical sheet
132: second optical sheet 160, 260: dot pattern
161: optical pattern 270: concave / convex pattern

Claims (16)

A light source for generating light,
A first optical sheet and a second optical sheet for condensing and diffusing the light source,
And a light guide plate for converting light generated from the light source into a surface light source,
Wherein a plurality of dot patterns are formed on the lower surface of the light guide plate and a plurality of optical patterns are formed in the dot pattern to refract and reflect the light generated from the light source and incident into the light guide plate,
Wherein a planar section is formed between the optical patterns and an uneven surface is formed in the planar section.
The backlight unit according to claim 1, wherein the optical pattern has a non-inverted triangle or a non-inverted quadrilateral cross-section.
The optical sheet as claimed in claim 2, wherein when the optical pattern is a non-inverted quadrangular structure, first and second inclined surfaces adjacent to both sides of the planar section are formed, and the second inclined plane is longer than the first inclined plane Backlight unit.
The backlight unit according to claim 3, wherein the inclination angle formed by the first inclined surface from the vertex of the optical pattern is in the range of 65 ° to 80 ° with respect to the reference line parallel to the lower surface of the light guide plate.
The backlight unit according to claim 3, wherein the inclination angle formed by the second inclined plane from the vertex of the optical pattern is in the range of 40 ° to 50 ° with respect to the reference line parallel to the lower side of the light guide plate.
The backlight unit according to claim 2, wherein a height of the optical pattern is in a range of 20 to 40 占 퐉.
The backlight unit according to claim 1, wherein the upper surface of the light guide plate further includes a plurality of concave-convex patterns corresponding to the plurality of dot patterns formed on the lower side.
The backlight unit according to claim 3, wherein the first inclined surface and the second inclined surface of the optical pattern are formed in a direction perpendicular to the light propagating from the light source into the light guide plate.
A liquid crystal display panel; And
And a backlight unit for supplying light to the liquid crystal display panel,
The backlight unit includes:
A light source for generating light,
A first optical sheet and a second optical sheet for condensing and diffusing the light source,
And a light guide plate for converting light generated from the light source into a surface light source,
Wherein a plurality of dot patterns are formed on the lower surface of the light guide plate and a plurality of optical patterns are formed in the dot pattern to refract and reflect the light generated from the light source and incident into the light guide plate,
Wherein a plane section is formed between the optical patterns and an uneven surface is formed in the plane section.
The liquid crystal display device according to claim 9, wherein the optical pattern has a non-inverted triangle or a non-inverted quadrilateral cross-section.
The optical device according to claim 10, wherein, when the optical pattern is a non-inverted quadrangular structure, first and second inclined surfaces adjacent to both sides of the planar section are formed, and the second inclined surface is longer than the first inclined surface Liquid crystal display device.
The liquid crystal display device according to claim 10, wherein the inclination angle formed by the first inclined surface from the vertex of the optical pattern is in the range of 65 ° to 80 ° with respect to the reference line parallel to the lower surface of the light guide plate.
The liquid crystal display of claim 10, wherein the inclination angle formed by the second inclined surface from the vertex of the optical pattern is in the range of 40 ° to 50 ° with respect to the reference line parallel to the lower surface of the light guide plate.
The liquid crystal display device according to claim 10, wherein a height of the optical pattern is in a range of 20 to 40 mu m.
The liquid crystal display device according to claim 9, wherein a plurality of concave-convex patterns are formed on the upper side of the light guide plate so as to correspond to the plurality of dot patterns formed on the lower side.
The liquid crystal display of claim 11, wherein the first inclined surface and the second inclined surface of the optical pattern are formed in a direction perpendicular to the light traveling from the light source into the light guide plate.

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