KR101830600B1 - Backlight unit and liquid crystal display including the same - Google Patents

Abstract

A backlight unit capable of improving the light efficiency and obtaining a high luminance image by implementing a color image without using a color filter having a large optical loss and a liquid crystal display device including the same. The backlight unit according to the present invention comprises a white light source for generating white light, a light guide plate on which the white light is incident, a blue fluorescent sheet formed on the light guide plate for transmitting the white light, And a multicolor fluorescent sheet including a plurality of red fluorescent layers, a green fluorescent layer, and a transparent layer for transmitting light transmitted through the blue fluorescent sheet again.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY INCLUDING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit that generates red, green, and blue light, and a liquid crystal display that displays a high-luminance color image using the backlight unit.

2. Description of the Related Art A liquid crystal display (LCD) includes a liquid crystal panel including a thin film transistor (TFT) array for controlling the arrangement of liquid crystals, a color filter for color implementation, Backlight unit. A minimum unit for color implementation of a liquid crystal display device is referred to as a pixel, and the pixel again includes red (R), green (G), and blue (B) subpixels. (Which may further include yellow (Y) or white (W) subpixels)

Generally, light generated in the backlight unit is white light including both wavelengths of red, green, and blue light. As the white light passes through the color filter of the liquid crystal panel, only the wavelength corresponding to the hue of each color filter is transmitted and the wavelengths of the other two colors are absorbed. Therefore, in the conventional liquid crystal display device, the light utilization efficiency is significantly lowered by using the color filter.

1 is a configuration diagram of a conventional liquid crystal display device.

1, a conventional liquid crystal display device includes a backlight unit 10 and a liquid crystal panel 20, and the liquid crystal panel 20 controls the transmittance of light through the orientation control of the liquid crystal layer 207 Green, and blue color filters 215a, 215b, and 215c for color implementation, and a TFT array substrate including a TFT (not shown in the drawing) and a pixel electrode 205 for forming a color image.

The TFT array substrate includes a pixel electrode 205 for controlling the light transmittance through liquid crystal alignment control of TFT active elements (not shown in the figure), red, green and blue color filters 215a, 215b and 215c regions, (203). Green, and blue subpixel regions are determined by gate electrode lines (not shown) and data electrode lines (not shown) of the TFT array substrate.

The color filter layer 215 is a structure for implementing a color image of the liquid crystal panel 20 and includes a top glass substrate 211 and a common electrode 209 and a black matrix 217 for preventing color mixing due to leakage of light, . A lower polarizer 201 for polarizing light emitted from the backlight unit 10 is disposed on the lower surface of the liquid crystal panel 20 and an upper polarizer 201 for polarizing the light transmitted through the color filter layer 215 is disposed on the upper surface of the liquid crystal panel 20. [ A polarizing plate 213 is disposed.

The white light L0 incident on the lower portion of the liquid crystal panel 20 from the backlight unit 10 includes all the wavelengths of red, green and blue light And the light transmittance is changed according to the arrangement direction of the liquid crystal layer 207 controlled by each of the sub-pixels corresponding to each color, thereby adjusting the color of each pixel.

The backlight unit 10 for irradiating the white light L0 to the liquid crystal panel 20 is positioned on the back surface of the liquid crystal panel 20. In this case, The backlight unit 10 includes a light source (not shown in the drawings) that generates light, a light guide plate 101 having a reflection plate disposed on the back surface thereof, a diffusion sheet 103, and a prism sheet 105. Light generated in the light source is condensed by the light guide plate 101 and passes through the diffuser sheet 103 and the prism sheet 105 which are optical sheets, and then is irradiated to the liquid crystal panel 20 (L0).

The white light generated from the light source of the backlight unit 10 is irradiated to the liquid crystal panel 20 and the lower polarizer 201, the TFT array substrate, the liquid crystal layer, the color filters 215a, 215b, and 215c, and the upper polarizer 213, And is mostly absorbed or blocked by the black matrix 217. Therefore, the amount of light emitted to the surface of the LCD is not more than about 10% of that of the first incident light source, resulting in a very low light efficiency and high power consumption due to low light efficiency. Particularly, the light transmitted through the color filters 215a, 215b, and 215c is about 30%, and 70% is absorbed and disappears, which is the component with the largest optical loss in the liquid crystal display device.

In recent years, there has been an increasing demand for low power consumption in order to realize high image quality, thin film, large size and energy saving of liquid crystal display devices. In particular, when 3D glasses are used for 3D image, luminance is reduced to about one tenth Therefore, improvement of the light efficiency of the liquid crystal display device is urgently required.

Disclosure of the Invention The present invention has been proposed in order to solve the above-mentioned problems, and it is an object of the present invention to provide a backlight unit capable of enhancing light efficiency and obtaining a high luminance image without using a color filter having a large optical loss, The purpose is to provide.

According to an aspect of the present invention, there is provided a liquid crystal display device including a backlight unit for generating red light, green light, and blue light, a liquid crystal panel for controlling a light amount of red light, green light, and blue light generated by the backlight unit, .

In the liquid crystal panel, red subpixels, green subpixels, and blue subpixels are formed corresponding to regions where red light, green light, and blue light generated by the backlight unit are incident, respectively.

Wherein the liquid crystal panel includes a liquid crystal layer formed between an upper glass substrate, a lower glass substrate, and upper and lower glass substrates, and a color filter layer is not formed on the upper glass substrate.

A backlight unit according to an embodiment of the present invention includes a white light source for generating white light, a light guide plate on which the white light is incident, a blue fluorescent sheet formed on the light guide plate for transmitting the white light, And a multi-color fluorescent sheet including a plurality of red fluorescent layers, a green fluorescent layer, and a transparent layer for transmitting light transmitted through the blue fluorescent sheet again.

Further, the backlight unit according to an embodiment of the present invention may further include a reflective layer formed on edge areas of the plurality of red fluorescent layers, the green fluorescent layer, and the transparent layer, and the reflective layer is formed on the same plane as the multi- Or may be formed between the blue fluorescent sheet and the multicolor fluorescent sheet.

A backlight unit according to another exemplary embodiment of the present invention includes a blue light source for generating blue light, a light guide plate on which the blue light is incident, a plurality of red fluorescent layers formed on the same plane of the light guide plate, And a multi-color fluorescent sheet including a transparent layer.

Further, the backlight unit according to another embodiment of the present invention may further include a reflective layer formed on the edge regions of the plurality of red fluorescent layers, the green fluorescent layer, and the transparent layer, wherein the reflective layer is formed on the same plane as the multi- , And may be formed between the light guide plate and the multi-color fluorescent sheet.

According to the present invention, since the red light, the green light, and the blue light are directly generated from the backlight unit and irradiated onto the liquid crystal panel, and the arrangement of the liquid crystal layers is controlled to adjust the light amount of each color, color images can be implemented without a color filter having a large light loss The light efficiency of the liquid crystal display device can be greatly increased.

Further, by using the blue light transmitted through the blue light source or the blue fluorescent sheet in the backlight unit, the brightness of the blue wavelength is improved and a high color reproduction rate can be obtained.

In addition, by concentrating the light into the sub pixel region through the reflective layer formed in the edge region of the fluorescent layer using the micropattern, the amount of light transmitted through the sub pixel can be increased and the luminance can be improved.

1 is a configuration diagram of a conventional liquid crystal display device.
2 is a block diagram of a liquid crystal display device according to an embodiment of the present invention.
3 is a plan view showing the multicolor fluorescent sheet 113 and the reflective layer 115 of the backlight unit 100 of FIG.
4 is a view showing another embodiment of a liquid crystal display device according to the present invention.

The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, which are not intended to limit the scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a liquid crystal display device according to an embodiment of the present invention.

2, a liquid crystal display according to an exemplary embodiment of the present invention includes a backlight unit 100 that generates red light L1, green light L2, and blue light L3, And a liquid crystal panel 200 for displaying a color image by controlling the amounts of red light L1, green light L2 and blue light L3.

The backlight unit 100 includes a white light source (not shown) for generating white light, a light guide plate 101 on which white light is incident, a blue fluorescent sheet 111 which is formed on the light guide plate 101 and transmits white light, A plurality of red fluorescent layers 113a, a green fluorescent layer 113b, and a transparent layer 113c, which are formed on the same plane of the upper portion of the fluorescent sheet 111 and again transmit the light transmitted through the blue fluorescent sheet 111 And a multicolor fluorescent sheet 113.

Green subpixels and blue subpixels are formed in the liquid crystal panel 200 corresponding to the regions where the red light L1, green light L2 and blue light L3 generated by the backlight unit 100 are incident .

In the present invention, the white light emitted from the light emitting source of the backlight unit 100 is transmitted through the blue fluorescent sheet 111 to generate blue light, and the red light L1, the green light L2, A red fluorescent layer 113a, a green fluorescent layer 113b, and a transparent layer 113c, which generate red, green and blue light L3, respectively, are formed. The red light L1, the green light L2 and the blue light L3 generated in this way are directly incident on the red, green and blue subpixels of the liquid crystal panel 200, respectively, to control the liquid crystal array of the subpixels, The green light L2 ', and the blue light L3' emitted from the light sources 200 and 200, thereby realizing a color image without a color filter.

The micropattern forming the blue fluorescent sheet 111 and the multicolor fluorescent sheet 113 may include all pixel patterns forming a conventional color substrate such as a strip, a mosaic, and a delta, and may be formed on the back surface of the prism substrate, Or may be made of a single sheet. In the case of the multicolor fluorescent sheet 113, red and green phosphors are applied to the sheet areas corresponding to the respective colors, and the blue areas are filled with the phosphors without applying the phosphors. When blue light is used by using the blue phosphor sheet 111, the blue phosphor is not necessary, so that the process can be simplified and the cost can be reduced.

The backlight unit 200 may further include a reflective layer 115 formed on an edge region of the red fluorescent layer 113a, the green fluorescent layer 113b, and the transparent layer 113c. The light emitted from the light guide plate 101 to the reflective layer 115 is not transmitted but is reflected back to the back surface of the light guide plate 101 so that the light path is changed and the light- So that the light can be focused on the pixels and the color mixture of adjacent pixels is prevented. The reflective layer 115 may have a concavo-convex pattern or a lattice pattern having a nano-interval, and the concave-convex pattern and the nano pattern may be formed by various methods such as photolithography and imprinting.

The light source of the backlight unit 100 may be a cold cathode fluorescent lamp, an OLED, an LED, a planar light source, or the like, and the light guide plate 101 may include various forms capable of forming a planar light source. The fluorescent material applied to the fluorescent sheets 111 and 113 may be an oxide, a nitride, a sulfide-based fluorescent material, a quantum dot fluorescent material, a hybrid fluorescent material, or the like, and may emit various colors such as yellow, purple, and orange in addition to red, Further phosphor may be used. The reflective layer 115 may be formed of a conductive material that does not transmit visible light, such as aluminum, copper, gold, silver, chromium, tungsten, nickel, titanium, (Ti), tantalum (Ta), molybdenum (Mo), neodymium (Nd), alloys thereof, and carbon nanotubes and graphenes.

The liquid crystal panel 200 includes a lower polarizer 201, a lower glass substrate 203, a pixel electrode 205, a liquid crystal layer 207, a common electrode 209, an upper glass substrate 211 and an upper polarizer 213 And red subpixels, green subpixels, and blue subpixels are formed corresponding to areas where the red light L1, green light L2, and blue light L3 are incident, respectively, generated in the backlight unit 100. [ The conventional color filter layer (Figs. 1 and 215) is not formed.

Each sub pixel region is bounded by a gate electrode line and a data electrode line of a TFT array substrate (not shown in the figure), and the common electrode 209 and the pixel electrode 205 The liquid crystal layer 207 is arranged. The transmissivity of the red light L1, the green light L2, and the blue light L3 emitted from the backlight unit 100 is adjusted according to the arrangement of the liquid crystal layer 207 to realize a color image without a color filter.

3 is a plan view showing the multicolor fluorescent sheet 113 and the reflective layer 115 of the backlight unit 100 of FIG.

As shown in FIG. 3, one pair of the red fluorescent layer 113a, the green fluorescent layer 113b, and the blue fluorescent layer 113c is formed to form one pixel region, and a plurality of such pixel regions are regularly arranged.

Green, and blue subpixel regions are determined by the data electrode line 121 and the gate electrode line 123 of the TFT array substrate when one pixel region is enlarged. A reflective layer 115 is formed in a region other than the subpixel to reflect light irradiated in the direction in which the data electrode line 121 and the gate electrode line 123 are arranged from the backlight unit 100 to be concentrated in the subpixel region The amount of light passing through the subpixel can be increased and the luminance can be improved.

4 is a block diagram of another embodiment of a liquid crystal display device according to the present invention.

4, the liquid crystal display according to another embodiment of the present invention may further include a yellow fluorescent layer 113d for generating yellow light L4 in the multicolor fluorescent sheet 113 in addition to the structure of FIG. And a yellow subpixel may be further formed in a region of the liquid crystal panel 200 where the yellow light L4 is incident.

The reflective layer 115 formed on the edge regions of the red fluorescent layer 113a, the green fluorescent layer 113b, the transparent layer 113c and the yellow fluorescent layer 113d is not formed on the same plane as the multicolor fluorescent sheet 113 But may be formed as a separate sheet 117 between the blue fluorescent sheet 111 and the multicolor fluorescent sheet 113. As described above, the multi-color fluorescent sheet 113 and the reflective layer sheet 117 are formed as a single sheet, thereby simplifying the manufacturing process of the backlight unit 100.

2 to 4, the present invention has been described on the assumption that the light source of the backlight unit 100 is a white light source. However, instead of the white light source, a blue light source that generates blue light may be used as a light source. In this case, the blue fluorescent sheet 111 shown in Fig. 2 and Fig. 4 is not required, and the multicolor fluorescent sheet 113 and the reflective layer 115 are formed on the same plane just above the light guide plate 101, 115 may be formed on the light guide plate 101 as an independent sheet 117 as shown in FIG. 4, and a multicolor fluorescent sheet 113 may be formed thereon.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

10, 100: backlight unit 20, 200: liquid crystal panel
101: light guide plate 103: diffusion sheet
105: prism sheet 111: blue fluorescent sheet
113: multicolor fluorescent sheet 113a: red fluorescent layer
113b: green fluorescent layer 113c: transparent layer
113d: yellow fluorescent layer 115: reflective layer
121: data electrode line 123: gate electrode line
201: lower polarizer 203: lower glass substrate
205: pixel electrode 207: liquid crystal layer
209: common electrode 211: upper glass substrate
213: upper polarizer 215: color filter layer
217: Black Matrix

Claims (14)

A white light source for generating white light;
A light guide plate to which the white light is incident;
A blue fluorescent sheet formed on the light guide plate and transmitting the white light; And
A plurality of red fluorescent layers, a green fluorescent layer, and a transparent layer, which are formed on the same plane of the blue fluorescent sheet and transmit the light transmitted through the blue fluorescent sheet again,
.
The method according to claim 1,
Further comprising a reflective layer formed on edge areas of the plurality of red fluorescent layers, green fluorescent layers, and transparent layers,
The reflective layer may be formed on the same plane as the multi-color fluorescent sheet, or may be formed between the blue fluorescent sheet and the multi-
Backlight unit.
The method according to claim 1,
The multicolor fluorescent sheet
And a plurality of yellow fluorescent layers for transmitting again the light transmitted through the blue fluorescent sheet
Backlight unit.
A blue light source for generating blue light;
A light guide plate on which the blue light is incident;
A multicolor fluorescent sheet formed on the same plane as the upper portion of the light guide plate and including a plurality of red fluorescent layers, a green fluorescent layer, and a transparent layer for transmitting the blue light; And
And a reflective layer formed as a single layer between the light guide plate and the multi-color fluorescent sheet, the reflective layer being formed corresponding to the edge regions of the red fluorescent layer, the green fluorescent layer, and the transparent layer in the multicolor fluorescent sheet.
delete 5. The method of claim 4,
The multicolor fluorescent sheet
Further comprising a plurality of yellow fluorescent layers for transmitting the blue light
Backlight unit.
1. A liquid crystal display comprising a backlight unit for generating red light, green light and blue light, and a liquid crystal panel for displaying a color image by controlling a light amount of red light, green light and blue light generated in the backlight unit,
The backlight unit
A white light source for generating white light;
A light guide plate to which the white light is incident;
A blue fluorescent sheet formed on the light guide plate and transmitting the white light; And
And a multicolor fluorescent sheet formed on the same plane as the upper portion of the blue fluorescent sheet and including a plurality of red fluorescent layers, a green fluorescent layer, and a transparent layer that again transmit the light transmitted through the blue fluorescent sheet
Liquid crystal display device.
8. The method of claim 7,
The backlight unit
Further comprising a reflective layer formed on edge areas of the plurality of red fluorescent layers, green fluorescent layers, and transparent layers,
The reflective layer may be formed on the same plane as the multi-color fluorescent sheet, or may be formed between the blue fluorescent sheet and the multi-
Liquid crystal display device.
8. The method of claim 7,
Green subpixels, and blue subpixels are formed in the liquid crystal panel in correspondence to areas where red light, green light, and blue light generated by the backlight unit are incident, respectively
Liquid crystal display device.
10. The method of claim 9,
The liquid crystal panel
An upper glass substrate;
A lower glass substrate; And
And a liquid crystal layer formed between the upper and lower glass substrates,
Characterized in that a color filter layer is not formed on the upper side glass substrate
Liquid crystal display device.
1. A liquid crystal display comprising a backlight unit for generating red light, green light and blue light, and a liquid crystal panel for displaying a color image by controlling a light amount of red light, green light and blue light generated in the backlight unit,
The backlight unit
A blue light source for generating blue light;
A light guide plate on which the blue light is incident;
A multicolor fluorescent sheet formed on the same plane as the upper portion of the light guide plate and including a plurality of red fluorescent layers, a green fluorescent layer, and a transparent layer for transmitting the blue light; And
And a reflective layer formed as a single layer between the light guide plate and the multi-color fluorescent sheet, the reflective layer being formed corresponding to the edge regions of the red fluorescent layer, the green fluorescent layer and the transparent layer in the multicolor fluorescent sheet.
delete 12. The method of claim 11,
Green subpixels, and blue subpixels are formed in the liquid crystal panel in correspondence to areas where red light, green light, and blue light generated by the backlight unit are incident, respectively
Liquid crystal display device.
14. The method of claim 13,
The liquid crystal panel
An upper glass substrate;
A lower glass substrate; And
And a liquid crystal layer formed between the upper and lower glass substrates,
Characterized in that a color filter layer is not formed on the upper side glass substrate
Liquid crystal display device.

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