KR101756670B1 - Backlight unit and liquid crystal display device using the same - Google Patents

Abstract

The present invention relates to a backlight unit capable of preventing a color difference defect, and a liquid crystal display using the same, which includes a light source unit including red, green, and blue light emitting diodes; A light guide plate on which light emitted from the light source unit is incident on an incident surface; And a plurality of color patterns formed on the incident surface; The plurality of color patterns include a first color filter made of a first color, a second color filter made of a second color, and a third color filter made of a third color.

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit capable of preventing a color difference defect and a liquid crystal display using the same.

2. Description of the Related Art In general, a liquid crystal display displays an image by adjusting the light transmittance of a liquid crystal having dielectric anisotropy using an electric field. To this end, the liquid crystal display device includes a liquid crystal panel in which liquid crystal cells are arranged in a matrix, a driving circuit for driving the liquid crystal panel, and a backlight unit for irradiating the liquid crystal panel with light.

BACKGROUND ART [0002] In recent years, an LED backlight unit using a light emitting diode (hereinafter, LED) having a high luminance and a low power consumption as a light source has attracted attention in comparison with an existing lamp.

1 is a schematic configuration diagram of a conventional LED backlight unit.

1, a conventional LED backlight unit 10 includes an LED light source unit 11 for providing light, a light guide plate 18 for guiding light provided from the LED light source unit 11, And a sheet 15.

The LED light source unit 11 includes a red LED 12R that emits red light, a green LED 12G that emits green light, and a blue LED 12B that emits blue light. As such, the red, green, and blue light emitted from the LED light source unit 11 are mixed with each other to provide white light.

However, in the region adjacent to the LED light source portion 11, red, green, and blue light are not mixed well and are incident on the light guide plate 18, and a color difference defect occurs in which red, green, and blue light appear in the light guide plate 18 There is a problem. Such a color difference difference problem has a problem of degrading the quality of the backlight unit and deteriorating the image quality of the liquid crystal display device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a backlight unit and a liquid crystal display device using the same, which can prevent a color difference defect.

According to an aspect of the present invention, there is provided a backlight unit including: a light source unit including red, green, and blue light emitting diodes; A light guide plate on which light emitted from the light source unit is incident on an incident surface; And a plurality of color patterns formed on the incident surface; The plurality of color patterns include a first color filter made of a first color, a second color filter made of a second color, and a third color filter made of a third color.

The first color filter is located to correspond to the red light emitting diode, the second color filter is located to correspond to the green light emitting diode, and the third color filter is located to correspond to the blue light emitting diode.

And the first through third color filters are sequentially arranged corresponding to the arrangement of the red, green and blue LEDs.

The width of each of the first to third color filters is set to be equal to or greater than the width of each of the red, green and blue light emitting diodes, and each of the first to third color filters is not separated from each other.

The first color is set to green, the second color is set to blue, and the third color is set to red.

The shape of the first to third color filters may be any one of a rectangle, a circle, an ellipse, and a trapezoid.

And the first through third color filters include a plurality of dot patterns.

The plurality of dot patterns may have any one shape selected from a circle, a square, and a regular hexagon, and the distances between the plurality of dot patterns are all set to be the same.

And the plurality of color patterns are further formed on the upper surface of the light guide plate adjacent to the incident surface.

According to another aspect of the present invention, there is provided a liquid crystal display comprising: a liquid crystal panel having a plurality of pixels; A panel guide surrounding the edge of the liquid crystal panel; A top cover which covers the panel guide and is fastened to the cover bottom; And a backlight unit including at least one of various technical features as described above for irradiating light to the liquid crystal panel.

The present invention converts red, green, and blue light emitted from the LED 141 into yellow, cyan, and magenta lights by forming a plurality of color patterns 155 on the incident surface of the light guide plate 130. The converted light can be easily mixed with white light in the light guide plate 130, and as a result, it is possible to prevent the color difference of red, green, and blue light from being generated.

1 is a schematic configuration diagram of a conventional LED backlight unit.
2 is an exploded perspective view illustrating a liquid crystal display device according to an embodiment of the present invention.
3 is a perspective view showing a part of the light guide plate 130 shown in FIG.
Fig. 4 is an enlarged view of the plurality of color patterns 155 shown in Fig.
5A to 5E are views showing the shapes of the first to third color filters 155a, 155b and 155c according to various embodiments.
6 is a perspective view showing a part of a light guide plate 130 according to another embodiment of the present invention.
7A and 7B are diagrams for explaining the effect of the present invention.

Hereinafter, a backlight unit according to an embodiment of the present invention and a liquid crystal display using the same will be described in detail with reference to the accompanying drawings.

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

2 includes a cover bottom 110, a reflection plate 120 positioned on the cover bottom 110, a light guide plate 130 positioned on the reflection plate 120, a light guide plate 130 disposed on the light guide plate 130, An optical member 150 positioned on the light guide plate 130, a liquid crystal panel 160 positioned on the optical member 150, a panel guide 160 surrounding the edge of the liquid crystal panel 160, And a top cover 180 that covers the panel guide 170 and the cover bottom 110.

The cover bottom 110 and the top cover 180 serve as a case of the liquid crystal display device 100 and include a reflector 120, a light guide plate 130, an LED light source 140, The unit 190 and the liquid crystal panel 160 are accommodated. The cover bottom 110 is formed in a rectangular plate shape, and the top cover 180 is formed in a rectangular frame shape so that they can be coupled to each other.

The reflector 120 positioned on the cover bottom 110 reflects the light emitted from the light guide plate 130 to the front and may be made of a metal having a high reflectance.

The light guide plate 130 positioned on the reflection plate 120 guides light incident from the LED light source 140 and converts the light source into a surface light source. The light guide plate 130 is made of PMMA (Poyl Methyl Methacrylate) having a high total reflectance.

Meanwhile, the light guide plate 130 according to the embodiment includes a plurality of color patterns 155, and the plurality of color patterns 155 are formed on the incident surface on which the light from the LED light source 140 is incident. Such a plurality of color patterns 155 serve to prevent color differences, and will be described later in detail.

The LED light source 140 may be formed on at least one side of the light guide plate 130 along the major axis direction of the light guide plate 130 or at least one side of each side of the light guide plate 130 have. The light emitted from the LED light source 140 may be directly incident into the light guide plate 130 or may be incident on a part of the LED light source 140. For example, And may be incident into the light guide plate 130 after being reflected by the housing.

The LED light source 140 may have a plurality of LEDs 141 arranged on the PCB 142. A reflection plate (not shown) may be disposed on the PCB 142 to reflect light emitted from the LED 141.

The optical member 150 positioned on the light guide plate 130 serves to diffuse or condense the light incident from the light guide plate 130. The optical member 150 includes a diffusion sheet 151 and a light condensing sheet 152. The diffusion sheet 151 serves to diffuse the light incident from the light guide plate 130 and to uniform the brightness of light. The light collecting sheet 152 may be a prism sheet, a microlens sheet, a lenticular lens sheet, or the like, and collects light to improve brightness.

The liquid crystal panel 160 positioned on the optical member 150 may include a first substrate 161 and a second substrate 162 that are bonded together in a lattice-like manner with a liquid crystal layer interposed therebetween, have.

A plurality of pixels are defined by a plurality of gate lines and data lines intersecting each other in a matrix form on a first substrate 161 called a TFT array substrate. Each pixel is provided with a thin film transistor (TFT) capable of turning on / off a signal and a pixel electrode connected to the thin film transistor.

Green (G), and blue (B) color filters respectively corresponding to a plurality of pixels and a color filter including a gate line, a data line, and a thin film transistor And a black matrix for covering non-display elements of the display device. In addition, the second substrate 162 may be provided with a transparent common electrode that covers the first substrate 161 and the second substrate 162, and the common electrode may be provided on the first substrate 161 according to the liquid crystal mode.

A printed circuit board 166 is connected to at least one side of the liquid crystal panel 160 via a flexible circuit board or a connection member 164 such as a tape carrier package Or the back surface of the cover bottom 110. The cover bottom 110 may be formed of a metal or the like.

When the thin film transistor selected for each gate line is turned on by the on / off signal of the gate driving circuit transferred from the gate line, the liquid crystal panel 160 having the above structure has the data voltage of the data driving circuit through the data line And is transmitted to the corresponding pixel electrode. Then, the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode to control the transmittance.

Hereinafter, a plurality of color patterns 155 formed on the light guide plate 130 will be described in more detail in order to prevent color differences.

3 is a perspective view showing a part of the light guide plate 130 shown in FIG. 4 is an enlarged view of the plurality of color patterns 155 shown in FIG. 3 shows an incident surface of the light guide plate 130 on which light is incident, and only the LED 141 and the plurality of color patterns 155 are shown in FIG.

Referring to FIG. 3, a plurality of color patterns 150 are positioned on an incident surface of the light guide plate 130. The plurality of color patterns 150 include a first color filter 155a of a first color, a second color filter 155b of a second color, and a third color filter 155c of a third color do.

4, the LED 141 includes a red LED 141R that emits red light, a green LED 141G that emits green light, and a blue LED 141B that emits blue light. do.

At this time, the first color filter 155a is positioned to correspond to the red LED 141R, the second color filter 155b is positioned to correspond to the green LED 141G, and the third color filter 155c is positioned to correspond to the blue LED 141B ). The first to third color filters 155a, 155b, and 155c may be sequentially arranged corresponding to the arrangement of the red, green, and blue LEDs 141R, 141G, and 141B.

The width W1 of each of the first to third color filters 155a, 155b and 155c is equal to or greater than the width W2 of each of the red, green and blue LEDs 141R, 141G and 141B. And the first to third color filters 155a, 155b and 155c are formed so as not to be separated from each other. Accordingly, the embodiment is configured such that the red, green, and blue light emitted from the red, green, and blue LEDs 141R, 141G, and 141B are emitted between the first to third color filters 155a, 155b, and 155c .

The colors of the first to third color filters 155a, 155b and 155c are set so that red, green, and blue light emitted from the LED 141 are easily mixed. For example, the first color of the first color filter 155a is set to green, the second color of the second color filter 155b is set to blue, and the index of the third color filter 155c Three colors can be set to red.

Accordingly, in the embodiment, the red light emitted from the red LED 141R is realized as yellow light through the first color filter 155a of green, and the green light emitted from the green LED 141G is formed as blue light Cyan light through the second color filter 155b and blue light emitted from the blue LED 141B is realized as magenta light through the red third color filter 155c. Then, the yellow, cyan, and magenta lights incident on the light guide plate 130 are mixed to realize white light.

In the above, setting the first color to green, setting the second color to blue, and setting the third color to red are just one example. That is, the first to third colors may be any color so as to easily mix the red, green, and blue light emitted from the red, green, and blue LEDs 141R, 141G, and 141B.

4, the first to third color filters 155a, 155b and 155c have a rectangular shape, but the shapes of the first to third color filters 155a, 155b and 155c may be variously changed .

5A to 5E are views showing the shapes of the first to third color filters 155a, 155b and 155c according to various embodiments.

Referring to FIG. 5A, the first through third color filters 155a, 155b, and 155c may have a circular or elliptic shape in order to effectively mix light incident from the LED 141. FIG. The light emitted from the LED 141 is widely spread with a radiation angle of about 120 degrees, and the first to third color filters 155a, 155b and 155c of the circular or elliptical shape are intended to cover such a radiation angle. Of course, it is preferable that the size of the circle or the ellipse is set to be larger than the area illuminating the incident surface of the light guide plate 130 by the light emitted from one LED 141.

Also, the first to third color filters 155a, 155b, and 155c may have a trapezoidal shape in order to effectively mix light incident from the LED 141. Here, as shown in FIG. 5B, the shape of the trapezoid is such that a long side having a longer trapezoid is disposed on the upper side, and a shorter side having a shorter length is disposed on the lower side. On the other hand, as shown in FIG. 5C, a long side having a long trapezoid is disposed on the lower side and a short side having a shorter length can be disposed on the upper side. In addition, as shown in FIG. 5D, a long side having a long trapezoid and a short side having a short trapezoid may be formed so as to be engaged with each other.

5E, the first to third color filters 155a, 155b, and 155c may include first to third color filters 155a, 155b, and 155c to efficiently mix light incident from the LEDs 141, 155b, and 155c may include a plurality of dot patterns 157, respectively.

The plurality of dot patterns 157 may have a circular shape, a square shape, a regular hexagonal shape, or the like, and the distance between adjacent dot patterns 157 may be uniform.

6, a plurality of color patterns 155 may be formed on the incident surface, and may be formed on the upper surface of the light guide plate 130 adjacent to the incident surface, as shown in FIG. 6 . When a plurality of color patterns 155 are formed on the upper surface of the light guide plate 130, it is preferable that a plurality of color patterns 155 are formed in the non-display region of the liquid crystal panel 160.

As described above, in the embodiment, a plurality of color patterns 155 are formed on the light guide plate 130 to efficiently mix the light emitted from the LED 141. In the embodiment, the shape and position of the color pattern 155 are not limited to the above examples, and any structure is possible as long as it is a structure for efficiently mixing light emitted from the LED 141.

7A and 7B are diagrams for explaining the effect of the present invention. Specifically, FIG. 7A is a photograph of driving a backlight unit according to the related art, and FIG. 7B is a photograph of driving a backlight unit according to the present invention.

Referring to FIG. 7A, in the conventional backlight unit, red, green, and blue light are visually observed in a region adjacent to the LED, and a color difference is generated.

On the other hand, it can be seen that red, green, and blue light are not visible in the region adjacent to the LED, as shown in FIG. 7B.

That is, the present invention converts red, green, and blue light emitted from the LED 141 into yellow, cyan, and magenta light by forming a plurality of color patterns 155 on the incident surface of the light guide plate 130. The converted light can be easily mixed with white light in the light guide plate 130, and as a result, it is possible to prevent the color difference of red, green, and blue light from being generated.

Therefore, the present invention can improve the quality of the backlight unit and further improve the image quality of the liquid crystal display device.

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 general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of.

130: light guide plate 155a: first color filter
155b: second color filter 155c: third color filter

Claims (10)

A light source section including red, green, and blue light emitting diodes;
A light guide plate on which light emitted from the light source unit is incident on an incident surface; And
And a plurality of color patterns formed on an upper surface of the light guide plate adjacent to the incident surface;
A plurality of color patterns corresponding to the red light emitting diodes, a first color filter having a green color, a second color filter having a blue color corresponding to the green light emitting diodes, And a third color filter made up of a third color filter. delete The method according to claim 1,
The first through third color filters
Wherein the plurality of light emitting diodes are sequentially arranged corresponding to the arrangement of the red, green, and blue light emitting diodes. The method of claim 3,
The width of each of the first to third color filters is set to be equal to or greater than the width of each of the red, green, and blue light emitting diodes,
Wherein each of the first to third color filters is not separated from each other. delete The method according to claim 1,
Wherein the shape of the first to third color filters has a shape selected from a quadrangle, a circle, an ellipse, and a trapezoid. The method according to claim 1,
Wherein the first to third color filters include a plurality of dot patterns. 8. The method of claim 7,
Wherein the plurality of dot patterns have any one shape selected from a circle, a square, and a regular hexagon,
And the distance between the plurality of dot patterns is set to be the same. delete A liquid crystal panel in which a plurality of pixels are formed;
A panel guide surrounding the edge of the liquid crystal panel;
A top cover which covers the panel guide and is fastened to the cover bottom;
And a backlight unit according to claim 1 for emitting light to the liquid crystal panel.

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