KR100783606B1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is disclosed. By overlapping the color pixels formed on the color filter substrate to a specified width to prevent light leakage without a black matrix, some or all of the signal lines for supplying power to the reflective electrode are placed under the reflective electrode to prevent additional light leakage. prevent. This has the effect of blocking unwanted light leakage in the liquid crystal display panel.

LCD, reflective electrode, optical leakage

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

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

FIG. 2 is a conceptual diagram of the liquid crystal display panel of FIG. 1.

3 is a conceptual diagram of a TFT substrate of a conventional liquid crystal display panel.

4 is a conceptual diagram of a color filter substrate of a conventional liquid crystal display panel.

5 is a longitudinal cross-sectional view of a conventional liquid crystal display device.

6 is an external perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

7 is a conceptual diagram of a color filter substrate according to an embodiment of the present invention.

8A is a conceptual diagram of a TFT substrate according to an embodiment of the present invention.

8B is a cross-sectional view of a TFT substrate according to an embodiment of the present invention.

9 is a longitudinal cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

10 is a longitudinal cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which the display brightness is greatly improved by improving the aperture ratio of the display area.                         

In general, a liquid crystal display device is a display device that displays an image by precisely controlling a liquid crystal having optical anisotropy. The liquid crystal display device defined as described above is generally classified into four types according to the method of using light such as a transmissive liquid crystal display device, a reflective liquid crystal display device, a reflection-transmissive liquid crystal display device, and a front illumination type reflective liquid crystal display device.

In this case, the transmissive liquid crystal display device, which is mainly used for a large display device, has a merit that the display can be performed anywhere regardless of the presence of light because it generates light and uses it for the display.

In addition, unlike the transmissive liquid crystal display, the reflective liquid crystal display performs display using external light and is mainly used for small and medium size liquid crystal display. This reflective liquid crystal display device has an advantage of minimizing power consumption.

Also, in recent years, a reflection-transmissive liquid crystal display which operates similarly to a reflective liquid crystal display in a place having a sufficient amount of light to perform a display, and which is similar to a transmissive liquid crystal display in a place having a light amount insufficient to perform a display. Devices and front-illumination reflective LCDs have been developed.

In this case, the reflective-transmissive liquid crystal display device has a unique structure having both the structure of the transmissive liquid crystal display device and the structure of the reflective liquid crystal display device, whereas in the case of the front illumination type liquid crystal display device, as shown in FIG. The front lighting device is added to the structure of the display device.

More specifically, referring to FIG. 1, the front illumination type liquid crystal display device 10 includes a light source 1, a light guide plate 2, and a reflective liquid crystal display panel 3 as a whole.

At this time, the light source 1 is used as a point light source LED, or a cold cathode ray tube as a linear light source. The light generated by the light source 1 is incident on the liquid crystal display panel 3 after the optical distribution of the surface light source is changed in the light guide plate 2.

At this time, the liquid crystal display panel 3 is composed of a color filter substrate 3a, a liquid crystal 3b, and a TFT substrate 3c as shown in FIG. At this time, the liquid crystal display panel 3 is coupled to the color filter substrate 3a and the TFT substrate 3c so as to face each other, and the liquid crystal 3b is formed therebetween.

The TFT substrate 3c is composed of a plurality of reflective electrodes 4 having a matrix arrangement again as shown in FIG. 3 and a power supply 5 for separately supplying power to each of the reflective electrodes 4.

In order for the power supply device 5 to individually supply power to the reflective electrode 4, two signals are applied to drive the thin film transistor 5a and the thin film transistor 5a matched one by one to the reflective electrode 4. Lines 5b and 5c are required.

In this case, the thin film transistor 5c includes a gate electrode G, a channel layer C, a source electrode S, and a drain electrode D. FIG.

In this case, the two signal applying lines 5b and 5c are the gate line 5b connected to the gate electrode G and the data line 5c connected to the source electrode S. FIG. At this time, the gate line 5b and the data line 5c pass through a portion corresponding to the space formed between the reflective electrodes 4.                         

As illustrated in FIG. 5, a transparent alignment layer 6 is formed on the reflective electrode 4, and an alignment layer 6a is formed in the alignment layer 6 in the first direction.

Meanwhile, since the color filter substrate 3a is superimposed on the TFT substrate 3c described above, a more specific configuration of the color filter substrate 3a will be described with reference to FIG. 4 or 5.

4 or 5, the color filter substrate 3a is again formed of the glass substrate 7, the black matrix 8a, the color pixels 8b, 8c, and 8d, the common electrode 9, and the alignment layer 11. It is composed of

The black matrix 8a serves to cover a region between the reflective electrode 4 and the reflective electrode 4 formed on the TFT substrate 3c. At this time, the black matrix 8a is much larger than the distance between the reflective electrode 4 and the reflective electrode 4 as shown in FIG. For example, when the space | interval of the reflection electrode 4 and the reflection electrode 4 is 4 micrometers, the width | variety of the black matrix 8a is about 11 micrometers.

At this time, the width of the black matrix 8a is wider than the distance between the reflective electrode 4 and the reflective electrode 4 and the light leaked by the declination line and the light emitted from the reflective electrode 4 and then obliquely emitted This is to prevent even light leakage by the.

Meanwhile, as illustrated in FIG. 4 or 5, RGB color pixels 8a, 8b, and 8c are formed at the same position as that of the reflective electrode 4.

At this time, the alignment layer 11 is again formed on the common electrode 9 while the common electrode 9 is formed on the glass substrate 7 on which the RGB color pixels 8a, 8b and 8c are formed.

The liquid crystal 3b is injected between the TFT substrate 3c and the color filter substrate 3a having such a configuration and then sealed.

The most important thing in the liquid crystal display panel having such a structure is the aperture ratio in the pixel. In this case, the aperture ratio refers to an area where light is emitted from a pixel. That is, the larger the aperture ratio, the more light is emitted and the display brightness is higher, and the smaller the aperture ratio is, the less light is emitted and the display brightness is lower. When the display brightness is low, the display quality generally decreases.

4 or 5, however, the black matrix 8c prevents a part of the light passing through the reflective electrode 4 and the liquid crystal 3b from being emitted to the outside. That is, in the conventional liquid crystal display device, the black matrix 8a causes the aperture ratio to be greatly reduced. Nevertheless, the black matrix 8a is inevitably used in the absence of the black matrix 8a. As described above, various problems may occur such as light leakage and color mixing when the liquid crystal 8b is not controlled. Because.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a liquid crystal display device in which light leakage, color mixing, and aperture ratio are maximized where a liquid crystal is not controlled without using a black matrix. have.

The liquid crystal display device for realizing the object of the present invention includes (a) a thin film transistor arranged in a matrix form and two power supply lines arranged in a grid so that power is supplied to a gate electrode and a source electrode of the thin film transistor. (B) an organic insulating layer including a contact hole through which the drain electrode of the thin film transistor is exposed, (c) a reflective electrode connected in part to each drain electrode and arranged in a matrix to reflect light; d) a first substrate comprising alignment films having alignment grooves having a first direction, (a) color pixels overlapping each reflective electrode and overlapping between the reflective electrode and the reflective electrode, (b) overlapping colors A planarization film formed on the upper surface of the pixels to reduce step coverage, (c) a common electrode formed on the upper surface of the planarization film, and (d) a boat having a second direction on the upper surface of the common electrode And a second substrate, a first substrate and a liquid crystal injected between the two substrates comprises an alignment film groove is formed.

Hereinafter, a unique operation and effects of the liquid crystal display according to the preferred embodiment of the present invention will be described in detail.

6 is a perspective view of the liquid crystal display 200 according to the exemplary embodiment of the present invention. Referring to the accompanying drawings, the liquid crystal display 200 is composed of a liquid crystal display panel 230 in which the light source 210, the light guide plate 220, and the black matrix are not formed, and the aperture ratio and luminance are greatly increased.

More specifically, the light source 210 may be a cold cathode ray tube lamp that is a linear light source, or an LED that is a point light source. In the present invention, a cold cathode ray tube lamp 210, which is a light source, is used as a light source. Reference numeral 215 is a lamp reflector which serves to emit light generated radially from the cold cathode ray tube lamp 210 to only one side.

Light generated by the lamp reflector 215 is input to the light guide plate 220 again. At this time, the light guide plate 220 has a rectangular parallelepiped plate shape in one embodiment, and changes the light having the linear light source optical distribution to the surface light source optical distribution. In this case, the light emitted from the light guide plate 220 is supplied to the liquid crystal display panel 230.

The liquid crystal display panel 230 is composed of a color filter substrate 240, a liquid crystal 250, and a TFT substrate 260.

7 is a color filter substrate 240 according to an embodiment of the present invention, and a TFT substrate 260 is illustrated in FIG. 8A or 8B.

The color filter substrate 240 is composed of the glass substrate 241, the color pixel 242, the common electrode 243, the alignment layer 244, and the polymer flat layer 245.

In this case, the color pixels 242a, 242b, 242c; 242 are formed on the glass substrate 241. At this time, specifically, the color pixel 242 is composed of a red color pixel 242a, a green color pixel 242b, and a blue color pixel 242c. The red color pixel 242a filters out only light having a red wavelength, and the green color pixel 242b filters out only light having a green wavelength, and the blue color 242c filters only light having a blue wavelength. Filter as much as possible.

At this time, in one embodiment, the red color pixel 242a, the green color pixel 242b, and the blue color pixel 240c overlap again as shown in FIG. 7 or 9.

In the following, overlapping positions are shown by reference numerals 240d and 242e. As described above, in the portion 242d where the red color pixel 242a and the green color pixel 242b overlap or where the green color pixel 242b and the blue color pixel 242c overlap, the light transmittance rapidly decreases. At this time, the width of the overlapped portion of the color pixel 242 is about 5㎛.

As such, when the color pixels 242 overlap with each other with a width of 5 μm, the aperture ratio can be greatly improved as compared with the conventional art illustrated in FIG. 5. For example, while the aperture ratio in the prior art is only 73%, the aperture ratio is greatly improved to 87% in the present invention.

On the other hand, as the color pixels 242 overlap, the step coverage is not good in the portion where the color pixels 242 overlap. As described above, display failure occurs due to poor step coverage at the portion where the color pixels 242 overlap.

In order to prevent this, in the present invention, a transparent polymer flattening film 245 is formed on the upper surface of the glass substrate 241 in a state where the color pixels 242 overlap the color filter substrate 240. In this case, the polymer planarization layer 245 has a thickness of about 1.3 μm and lowers the step coverage to 600 μs or less.

Meanwhile, the TFT substrate 260 is shown in more detail in the accompanying FIG. 8A or 8B. Referring to FIG. 8B, the TFT substrate 260 is again composed of a glass substrate 261, a reflective electrode 262, and a power supply 263.

The power supply 263 is composed of a thin film transistor 264 and a signal applying line 265 for operating the thin film transistor 264 as shown in FIG. 8A or 8B.

In this case, the thin film transistor 264 includes a gate electrode 264a, an insulating film 264b, channel layers 264c and 264d, a source electrode 264e, and a drain electrode 264f.                     

More specifically, the gate electrode 264a is formed by patterning a gate metal thin film formed on the entire surface of the glass substrate 261 in a matrix form as shown in FIG. 8A.

At this time, in the process of forming the gate electrode 264a, the gate line 265a, which is one of the signal lines for operating the thin film transistor 264, is connected to the gate electrode 264a. The gate line 265a is commonly connected to all the gate electrodes 264a belonging to one column.

On the other hand, the insulating film 264b is formed to a predetermined thickness over the entire surface of the glass substrate 261 so that the gate electrode 264a is covered. The insulating film 264b serves to prevent the gate electrode 264a and the channel layers 264c and 264d described later in detail from being shorted.

A channel layer (264a, 264d) is composed of amorphous silicon thin film layer (264a), the n ⁺ ions are doped n ⁺ amorphous silicon thin film layer (264b) on the upper surface of the insulating film (264b). At this time, the n ⁺ amorphous silicon thin film layer 264b is divided so as not to be shorted to each other.

On the other hand, the source electrode 264e and the drain electrode 264f are formed so as not to be mutually shorted on the upper surface of the n ⁺ amorphous silicon thin film layer 264b divided into two. In this case, as the source electrode 264e is patterned, the data line 264b is connected to the source electrode 264e as shown in FIG. 8A. In this case, the data line 264b is commonly connected to all of the source electrodes 264e belonging to a row.

In one embodiment, the organic insulating film 266 is formed on the glass substrate 261 again as shown in FIG. 8B while the power supply device 263 having such a configuration is formed on the glass substrate 261. The organic insulating layer 266 allows the power supply 263 described above to be insulated from the reflective electrode 267 to be described later.

Convex embossed irregularities are formed on the surface of the organic insulating film 266, and contact holes 266a are formed where the drain electrode 264f of each thin film transistor 264 is formed.

In this state, a light reflectance is high and a conductive metal thin film layer is formed on the entire surface of the organic insulating film 266. As shown in FIG. 8A, the metal thin film layer is patterned to be connected to the drain electrode 264f of each thin film transistor 264 so that the reflective electrode 262 is formed.

In this case, the position of the reflective electrode 262 is as shown in FIG. 9 in one embodiment, or as shown in FIG. 10 in one embodiment.

9 and 10 differ in the positional relationship between the reflective electrode 267 and the signal line 265. In detail, in FIG. 9, the signal line 265, for example, the data line 265a, is formed in a space formed between the reflective electrode 262 and the reflective electrode 262.

The optical characteristics of the liquid crystal display panel of FIG. 9 and the conventional liquid crystal display panel of FIG. 5 having such a configuration are compared with reference to <Table 1> as follows.

Conventional The present invention Change rate Backlight lights up Bright 7.9㏅ / ㎡ 11.1㏅ / ㎡ 41% increase gloominess 1.3㏅ / ㎡ 2.9㏅ / ㎡ 123% increase Luminance difference 5.8: 1 3.7: 1 36% reduction

Referring to Table 1, the aperture ratio was greatly increased by overlapping the color pixels formed on the color filter substrate 240, so that the brightness of the light increased by 41%, but the brightness in the dark also increased by 123%. For this reason, there exists a tendency for the brightness difference to fall somewhat compared with the past.

In view of this, in the present invention, as shown in FIG. 8A or 10, the signal line, for example, the data line 265a, has a configuration passing through the bottom surface of the reflective electrode 262.

The optical characteristics of the liquid crystal display panel of FIG. 10 and the conventional liquid crystal display panel of FIG. 5 having the configuration as described above are compared with reference to Table 2 as follows.

Conventional The present invention Change rate Backlight lights up Bright 9.7㏅ / ㎡ 11.3 ㏅ / ㎡ 16% up gloominess 2.06㏅ / ㎡ 2.49㏅ / ㎡ 21% up Luminance difference 4.7: 1 4.6: 1 2% reduction

According to Table 2, when the signal line 265 passes through the lower portion of the reflective electrode 262 while the color pixels overlap the color filter substrate 240, the lightness, darkness, and luminance of the light may be improved. have.

At this time, in the above-described embodiment, two color pixels are overlapped, for example, a red color pixel-a green color pixel, a green color pixel-a blue color pixel, a red color pixel-a blue color pixel, and is formed between the reflective electrode and the reflective electrode. Light leakage in the area was minimized.

However, in addition to the above method, the blue color pixel is superimposed on the region overlapping the red pixel-green pixel once more to obtain a triple layer, or the green pixel is once applied to the region overlapping the red pixel-blue pixel. By further overlapping to obtain a triple film, or by overlapping the red color pixel once more in the region where the green and blue color pixels are overlapped to obtain a triple film, further improved light leakage can be prevented.

As described in detail above, it is possible to greatly improve the aperture ratio of the liquid crystal display panel, and also to prevent the degradation of display quality in the liquid crystal display device by preventing the luminance deterioration that may occur in the process of improving the aperture ratio. Has

In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (7)

(a) a power supply comprising a thin film transistor arranged in a matrix form and two power supply lines arranged in a grid so that power is supplied to a gate electrode and a source electrode of the thin film transistor, and (b) a drain of the thin film transistor. An organic insulating layer including a contact hole through which the electrode is exposed, (c) a reflective electrode arranged in a matrix to reflect light with a portion connected to each of the drain electrodes, and (d) an alignment groove having a first direction A first substrate including alignment layers; (a) facing each of the reflective electrodes, and partially overlapping the colored pixels between the reflective electrode and the reflective electrode, (b) forming a step of the overlapped colored pixels formed in the overlapped portion of the colored pixels. A second substrate including a planarization film for reducing, (c) a common electrode formed on an upper surface of the planarization film, and (d) an alignment film having an alignment groove having a second direction on an upper surface of the common electrode; And And a liquid crystal injected between the first substrate and the second substrate. 2. The liquid crystal of claim 1, wherein the two power supply lines are a data line connected to the source electrode and a gate line connected to the gate electrode, and the data line is disposed at a position partially covered by the reflective electrode. Display. The method of claim 1, wherein the two power supply lines are a data line connected to the source electrode and a gate line connected to the gate electrode, and the data line and the gate line are disposed at a position covered by the reflective electrode. Liquid crystal display device. The method of claim 1, wherein the color pixel is composed of a red pixel emitting light having a red wavelength, a green pixel emitting light having a green wavelength, and a blue pixel emitting light having a blue wavelength. The overlap width of the color pixels is substantially the same as the gap between the reflective electrode and the reflective electrode. The liquid crystal display device according to claim 4, wherein the overlap width is 0.5 탆 to 0.6 탆. The liquid crystal display device according to claim 1, wherein the planarization film is made of a transparent polymer material, and the difference of the step coverage is 600 kW or less. A first substrate in which a thin film transistor, a gate line connected to a gate electrode of the thin film transistor, a data line connected to a source electrode, and a reflective electrode connected to a drain electrode of the thin film transistor are arranged in a matrix form; A transparent substrate facing the first substrate, a light blocking color pixel formed on the transparent substrate so as to face a pixel electrode of the first substrate, and formed between the reflective electrode and the reflective electrode, and facing the reflective electrode and having an edge A second substrate including an optical filter color pixel overlapping each other on the light blocking color pixel, a planarization film for reducing the step difference between the light blocking color pixel and the optical filter color pixel, and a common electrode formed on the planarization film; And And a liquid crystal injected between the first substrate and the second substrate.

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