KR20120052627A - Liquid crystal display - Google Patents

Abstract

According to an exemplary embodiment, a liquid crystal display device includes a light guide plate having a plurality of light guide plate patterns formed on one surface thereof, a light source provided at one side of the light guide plate, a first optical member disposed on the light guide plate, and a first light positioned on the first optical member. The liquid crystal panel may include a liquid crystal panel, a second optical member disposed under the light guide plate, a second liquid crystal panel disposed under the second optical member, and a reflective sheet positioned on the other surface of the light guide plate and including a plurality of holes.

Description

Liquid Crystal Display

The present invention relates to a liquid crystal display device, and to a liquid crystal display device that can improve light efficiency and reduce manufacturing cost.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, the demand for light and thin flat panel display devices can be gradually increased. Liquid crystal display (LCD), plasma display panel (PDP), organic light emitting diode (OLED), etc. are being actively researched as such flat panel display devices. BACKGROUND ART Liquid crystal display devices, which are easy to drive and easily implement high image quality, have been in the spotlight.

The liquid crystal display classified into a light receiving display device may include a backlight unit disposed below the liquid crystal panel to provide light to the liquid crystal panel in addition to the liquid crystal panel displaying an image.

Recently, in addition to a single-sided liquid crystal display device that implements light in only one direction, a double-sided liquid crystal display device that implements images on both sides has been developed. In the double-sided liquid crystal display, liquid crystal panels are positioned on both sides of the light guide plate for guiding light provided from the light source, thereby realizing images on both sides.

1 is a view showing a conventional double-sided liquid crystal display device.

Referring to FIG. 1, the conventional double-sided liquid crystal display device 10 includes a light source 11 for providing light, a light guide plate 12 for guiding light, and an optical member 13a positioned at upper and lower portions of the light guide plate 12, respectively. 13b) and liquid crystal panels 14a and 14b respectively positioned on the upper or lower portions of the optical members 13a and 13b.

The liquid crystal display 10 converts light provided from the light source 11 into a surface light source in the light guide plate 12 and provides the light to the liquid crystal panels 14a and 14b to implement an image. Here, the light guide plate patterns 15a and 15b are formed on the top and bottom surfaces of the light guide plate 12 to efficiently emit light totally reflected in the light guide plate 12.

The conventional liquid crystal display device configured as described above has a problem in that light efficiency decreases because light is reflected by the light guide plate patterns more and more as the number of light guide plate patterns formed on the light guide plate is larger. In addition, a manufacturing cost increases due to the process of forming the light guide plate patterns.

Accordingly, the present invention provides a liquid crystal display device that can improve light efficiency and reduce manufacturing cost.

In order to achieve the above object, a liquid crystal display according to an embodiment of the present invention is a light guide plate having a plurality of light guide plate patterns formed on one surface, a light source provided on one side of the light guide plate, a first optical member located on the light guide plate, A reflective sheet including a plurality of holes on a first liquid crystal panel positioned on a first optical member, a second optical member positioned below the light guide plate, a second liquid crystal panel positioned below the second optical member, and the other surface of the light guide plate. It may include.

The reflective sheet may be attached to the other surface of the light guide plate.

The diameter of the plurality of holes may be 200 to 400㎛.

The diameter of the plurality of holes may increase as the distance from the light source.

The distance between the plurality of holes may decrease as the distance from the light source increases.

The plurality of holes may have a polygonal shape of circular or square or more.

The reflective sheet may include a white pigment or bubbles in the resin.

The light guide plate pattern may increase in size away from the light source.

The gap of the light guide plate pattern may decrease as the distance from the light source is increased.

The first liquid crystal panel and the second liquid crystal panel may each be a double-sided type to implement an image.

The liquid crystal display according to an exemplary embodiment of the present invention forms an reflective sheet having a plurality of holes formed on one surface of the light guide plate, so that light incident from the light source may be efficiently emitted to the upper and lower portions of the light guide plate in the light guide plate. have. In addition, by attaching a reflective sheet having a plurality of holes, there is an advantage that can reduce the printing process of the light guide plate pattern to reduce the manufacturing cost.

1 is a view showing a conventional double-sided liquid crystal display device.
2 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.
3 is a cross-sectional view taken along line II ′ of FIG. 2;
4 is a plan view from above of the light guide plate of FIG. 3;
FIG. 5 is a plan view of the light guide plate of FIG. 3 viewed from below. FIG.
6A is a view showing an image of the front side of a conventional liquid crystal display, and FIG. 6B is a view showing an image of the front side of a liquid crystal display of the present invention.

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

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

Referring to FIG. 2, the liquid crystal display device 100 according to an exemplary embodiment may include a light guide plate 120, a light source 130 provided on at least one side of the light guide plate 120, and a first light guide plate disposed on the light guide plate 120. The optical member 140 includes a first liquid crystal panel 160 positioned on the first optical member 140. The second optical member 150 is disposed below the light guide plate 120, and the second liquid crystal panel 170 is disposed below the second optical member 150.

The upper panel guide 180a fixing the first optical member 140 and the first liquid crystal panel 160 is positioned, and the lower panel guide fixing the second optical member 150 and the second liquid crystal panel 170. 180b is located.

In more detail, the upper cover 110a and the lower cover 110b serve as a casing of the liquid crystal display device 100 to provide the light guide plate 120, the light source 130, and the first and second optical members 140 and 150. ) And the first and second liquid crystal panel 160 and the upper and lower panel guides 180a and 180b.

The upper cover 110a and the lower cover 110b may have a rectangular frame shape and may be coupled to each other.

The light guide plate 120 guides the light incident from the light source 130 to change the line light source into a surface light source. The light guide plate 120 is made of PMMA (PolyMethylMethAcrylate) having excellent total reflectance. Then, the light guide plate 120 provides the light of the light source to the top or bottom.

For example, at least one light source 130 may be formed on one side of the light guide plate 120 in the long axis direction of the light guide plate 120, or one or more light sources 130 may be formed on each side of the light guide plate 120. The light emitted from the light source 130 may be incident directly into the light guide plate 120.

The light emitted from the light source 130 may be incident directly into the light guide plate 120. The light source 130 may be an LED assembly, and the LED assembly may include a plurality of LED light sources 132 arranged on the LED PCB 131. A reflector (not shown) may be disposed on the LED PCB 131 to reflect light emitted from the LED light source 132.

Although the light source 130 has been described as an LED assembly in this embodiment, the present invention is not limited thereto. For example, a cold cathode fluorescent lamp (CCFL) and a hot cathode fluorescent lamp (HOT Cathode Fluorescent Lamp) HCFL) and an external electrode fluorescent lamp (EEFL), but is not limited thereto.

The first optical member 140 and the second optical member 150 respectively positioned above and below the light guide plate 120 serve to diffuse or collect light emitted from the light guide plate 120.

The first optical member 140 and the second optical member 150 are composed of diffusion sheets 141 and 151 and light collecting sheets 142 and 152, respectively. The diffusion sheets 141 and 151 diffuse the light incident from the light guide plate 120 and serve to make the luminance of the light uniform. In addition, the light collecting sheets 142 and 152 may be at least a prism sheet, a micro lens sheet, a lenticular lens sheet, and the like, and focus light to improve luminance.

Therefore, the backlight unit 200 including the light guide plate 120, the light source 130, and the first and second optical members 140 and 150 is configured.

The first liquid crystal panel 160 and the second liquid crystal panel 170 positioned on the first optical member 140 and the second optical member 150, respectively, are portions in which an image is realized, and the liquid crystal layer is interposed therebetween. The first substrate 161 and 171 and the second substrate 162 and 172 which are opposed to each other may be included.

Although not shown in the drawings, a plurality of pixels may be defined in the first substrates 161 and 171 called TFT array substrates by crossing a plurality of scan lines and data lines in a matrix shape. Each pixel may include a thin film transistor (TFT) capable of turning on / off a signal, and a pixel electrode connected to the thin film transistor may be positioned.

The second substrates 162 and 172, which are referred to as color filter substrates, include color filters of red (R), green (G), and blue (B) corresponding to a plurality of pixels, respectively, and surround the scan lines and the data lines. And a black matrix covering a non-display element such as a thin film transistor. In addition, a transparent common electrode covering them may be provided.

In addition, at least one side of the first and second liquid crystal panels 160 and 170 may be connected to the printed circuit board 163 through a connection member 164 or 174 such as a flexible circuit board or a tape carrier package (TCP). 173 may be connected and disposed in the upper panel guide 180a and the lower panel guide 180b during the modularization process.

When the thin film transistors selected for each scan line are turned on by the on / off signal of the gate driving circuit transmitted from the scan line, the first liquid crystal panel 160 and the second liquid crystal panel 170 having the above structure are turned on. The data voltage of the data driver circuit is transferred to the corresponding pixel electrode through the data line. Accordingly, the arrangement direction of the liquid crystal molecules may be changed by the electric field between the pixel electrode and the common electrode, thereby indicating a difference in transmittance.

The upper panel guide 180a and the lower panel guide 180b accommodate and support the first optical member 140, the first liquid crystal panel 160, the second optical member 150, and the second liquid crystal panel 170, respectively. It plays a role.

Accordingly, the liquid crystal display device 100 of the present invention may be configured to accommodate the backlight unit 200, the first liquid crystal panel 160, and the second liquid crystal panel 170. The liquid crystal display device 100 configured as described above may be a double-sided liquid crystal display device that may simultaneously implement an image on the first liquid crystal panel 160 and the second liquid crystal panel 170.

Meanwhile, the plurality of light guide plate patterns 121 are positioned on one surface of the light guide plate 120, and the reflective sheet 125 having a plurality of holes is formed on the other surface of the light guide plate 120.

3 is a cross-sectional view taken along line II ′ of FIG. 2. 3 illustrates the features of the light guide plate 120 and the reflective sheet 125 of the present invention, and the present invention is not limited thereto.

Referring to FIG. 3, a plurality of light guide plate patterns 121 are positioned on one surface of the light guide plate 120. The light guide plate patterns 121 may be formed in various planar shapes such as circles, ellipses, quadrangles, and rhombuses, and may be formed in an engraved or embossed shape on one surface of the light guide plate 120.

The light guide plate patterns 121 reflect and diffuse incident light. That is, the light guide plate patterns 121 destroy the total internal reflection condition at the interface between the light guide plate 120 and the external air layer, so that the light reflected and diffused from the light guide plate patterns 121 passes through the top surface of the light guide plate 120. After refraction.

4 is a top plan view of the light guide plate of FIG. 3.

Referring to FIG. 4, light in the light guide plate 120 is attenuated as it moves away from the light source 130, so that the luminance distribution appearing on the light guide plate 120 decreases gradually as it moves away from the light source 130.

In order to eliminate such luminance unevenness, the density of the light guide plate patterns 121 may increase gradually as the light guide plate pattern 121 moves away from the light source 130. The density change of the light guide plate patterns 121 may be realized by changing the number or size of the light guide plate patterns 121, and the density of the light guide plate pattern 121 is an area occupied by the light guide plate pattern 121 per unit area. It can be defined as.

For example, as shown in FIG. 4, the density change of the light guide plate pattern 121 may simultaneously change the gap P1 between the light guide plate patterns 121 and the size of the light guide plate pattern 121.

That is, as the light guide plate pattern 121 moves away from the light source 130, the gap P1 may decrease and increase in size. Accordingly, it can be seen that the number per unit area of the light guide plate pattern 121 gradually increases.

Referring to FIG. 3 again, a reflective sheet 125 having a plurality of holes 127 is disposed under the light guide plate 120. The upper surface of the reflective sheet 125 is disposed to face the lower surface of the light guide plate 120, and reflects light transmitted through the lower surface of the light guide plate 120 to be incident again into the light guide plate 120.

The reflective sheet 125 may be formed by dispersing a white pigment such as titanium oxide (TiO ₂ ) in a resin or bubbles for scattering light in the resin.

Here, the resin is a white synthetic resin, and examples thereof include polyethylene terephthalate (PET), polycarbonate (PC), poly stylene (PS), acrylic, cellulose acetate, and weather resistant vinyl chloride. Especially, PET which is excellent in heat resistance is preferable.

Examples of the pigment include titanium oxide (TiO ₂ ), zinc oxide (ZnO), lead carbonate (PbCO ₃ ), barium sulfate (BaSO ₄ ), calcium carbonate (CaCO ₃ ), and the like. Especially, titanium oxide with a large concealment improvement effect is preferable.

In addition, the bubbles dispersed in the resin may be, for example, MCPET (micro cellular foaming polyethylene terephthalate). In the case of MCPET, the microcellular foaming process (hereinafter referred to as "MCPs") is utilized to form micro bubbles on a micron scale inside the resin. Such microbubbles may exhibit reflection characteristics by acting as reflectors.

The reflective sheet 125 has a plurality of holes 127 through which light can be emitted. The plurality of holes 127 may be formed in various planar shapes such as a circle, an ellipse, a quadrangle, a rhombus, and may be formed in the form of a through hole in one surface of the reflective sheet 125.

The plurality of holes 127 diffuse the incident light. That is, the plurality of holes 127 destroy the internal total reflection condition at the interface between the light guide plate 120 and the outer air layer, so that light diffused from the plurality of holes 127 passes through the bottom surface of the light guide plate 120. After refraction.

FIG. 5 is a plan view of the light guide plate of FIG. 3 viewed from below. FIG.

Referring to FIG. 5, as described above, the light in the light guide plate 120 is attenuated as it moves away from the light source 130, and the luminance distribution appearing below the light guide plate 120 gradually decreases as it moves away from the light source 130. Will appear.

In order to eliminate such luminance unevenness, the densities of the plurality of holes 127 formed in the reflective sheet 125 may increase as the distance from the light source 130 increases. Here, the density change of the holes 127 may be implemented by changing the number or size of the holes 127, and the density of the holes 127 may be defined as an area occupied by the holes 127 per unit area. have.

For example, as shown in FIG. 5, the density change of the hole 127 may simultaneously change the size of the gap P2 and the hole 127 between the holes 127. Herein, the size of the hole 127 means the diameter d of the hole 127.

That is, as the hole 127 moves away from the light source 130, the gap P2 may decrease and the diameter d may increase. Accordingly, it can be seen that the number per unit area of the holes 127 gradually increases.

Here, the diameter (d) of the hole 127 may be 200 to 400㎛. When the diameter d of the hole 127 is 200 μm or more, there is an advantage that light can be efficiently emitted to the lower portion of the light guide plate 120 on which the reflective sheet 125 is located, and the diameter d of the hole 127. When the thickness is 400 μm or less, the light reflected to the upper portion of the light guide plate 120 may be reduced, thereby preventing the light emitted to the upper portion of the light guide plate 120 from being reduced.

Referring to FIG. 3 again, as described above, a plurality of light guide plate patterns 121 are formed on the light guide plate 120, and a reflective sheet 125 having a plurality of holes 127 is formed below the light guide plate 125. Is formed. Accordingly, there is an advantage that the light incident from the light source 130 can be efficiently emitted to the upper and lower portions of the light guide plate 120 in the light guide plate 120.

Table 1 shows the measurement of the amount of light and the light efficiency at the light exit surface of the light guide plate of the conventional liquid crystal display device and the liquid crystal display device of the present invention. 6A is a view showing an image of the front side of a conventional liquid crystal display device, and FIG. 6B is a view showing an image of the front side of a liquid crystal display device of the present invention.

Output surface of conventional light guide plate Light exit surface of light guide plate of the present invention Light quantity (lm) 576.55 663.03 Light efficiency (%) 100 115

Referring to Table 1 and FIGS. 6A and 6B, a liquid crystal display device in which a reflective sheet including a hole is formed on one surface of the light guide plate according to the present invention is compared with a conventional liquid crystal display device in which light guide plate patterns are formed on both surfaces of the light guide plate. It can be seen that the light quantity and the light efficiency are excellent in the light exit surface.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention forms a reflective sheet having a plurality of holes formed on one surface of the light guide plate, so that light incident from the light source may be efficiently emitted to the upper and lower parts of the light guide plate. There is an advantage to this. In addition, by attaching a reflective sheet having a plurality of holes, there is an advantage that can reduce the printing process of the light guide plate pattern to reduce the manufacturing cost.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

Claims (10)

A light guide plate having a plurality of light guide plate patterns formed on one surface thereof;
A light source provided on one side of the light guide plate;
A first optical member on the light guide plate;
A first liquid crystal panel positioned on the first optical member;
A second optical member positioned below the light guide plate;
A second liquid crystal panel disposed under the second optical member; And
And a reflective sheet disposed on the other surface of the light guide plate and including a plurality of holes.
The method of claim 1,
The reflective sheet is attached to the other surface of the light guide plate.
The method of claim 1,
The diameter of the plurality of holes is 200 to 400㎛ liquid crystal display device.
The method of claim 1,
The diameter of the plurality of holes increases as the distance from the light source.
The method of claim 1,
The plurality of holes spaced apart as the distance from the light source decreases.
The method of claim 1,
The plurality of holes is a liquid crystal display device having a polygonal shape of circular or rectangular shape or more.
The method of claim 1,
The reflective sheet is a liquid crystal display device comprising a white pigment or bubbles in the resin.
The method of claim 1,
The size of the light guide plate pattern increases as the distance from the light source.
The method of claim 1,
And a distance between the light guide plate patterns decreases away from the light source.
The method of claim 1,
And a double-sided liquid crystal display in which the first liquid crystal panel and the second liquid crystal panel each implement an image.

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