KR101233728B1 - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a horizontal field type liquid crystal display device, and more particularly, to a structure of a liquid crystal display device capable of preventing viewing angle crosstalk.

A liquid crystal display device according to the present invention includes a gate electrode, a gate wiring, and a plurality of common electrodes formed on an array substrate; A gate insulating layer formed on the array substrate including the gate electrode, the gate wiring, and a plurality of common electrodes; A semiconductor layer formed on the gate insulating layer to form a semiconductor pattern; A data line defining a plurality of pixels along with the source electrode, the drain electrode, and the gate wiring formed on the semiconductor layer; An interlayer insulating layer formed on the array substrate including the source electrode, the drain electrode, and the data wiring; A plurality of pixel electrodes formed on the interlayer insulating layer and formed to form a horizontal electric field together with the plurality of common electrodes; A color filter substrate bonded to the array substrate so as to be opposite to each other; And a black matrix formed on the color filter substrate and formed in a stripe shape in a direction parallel to the gate wiring, wherein a common electrode disposed below the data wiring among the plurality of common electrodes extends toward a neighboring pixel. And overlapping the data line to block backlight light.

LCD, Horizontal field type, Light leakage phenomenon, viewing angle crosstalk

Description

Liquid Crystal Display Device {LIQUID CRYSTAL DISPLAY DEVICE}

1A is a plan view showing a liquid crystal display device of the related art.

1B is a cross-sectional view showing a conventional liquid crystal display device

1C is a cross-sectional view illustrating a viewing angle crosstalk phenomenon in a liquid crystal display device of the related art.

1D is a cross-sectional view of a structure for preventing a viewing angle crosstalk phenomenon in a conventional liquid crystal display device.

2A is a plan view showing a liquid crystal display device according to a first embodiment of the present invention.

2B is a cross-sectional view illustrating a liquid crystal display device according to a first embodiment of the present invention.

2C is a cross-sectional view illustrating that viewing angle crosstalk is prevented from occurring in the liquid crystal display according to the first embodiment of the present invention.

3A is a plan view showing a liquid crystal display device according to a second embodiment of the present invention.

3B is a cross-sectional view showing that viewing angle crosstalk is prevented from occurring in the liquid crystal display according to the second embodiment of the present invention.

4A is a plan view showing a liquid crystal display device according to a third embodiment of the present invention.

4B is a cross-sectional view illustrating that viewing angle crosstalk is prevented from occurring in the liquid crystal display according to the third exemplary embodiment of the present invention.

5A is a plan view showing a liquid crystal display device according to a fourth embodiment of the present invention.

5B is a cross-sectional view illustrating that viewing angle crosstalk is prevented from occurring in the liquid crystal display according to the fourth embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

205,305,405,505: common electrode

215,315,415,515: pixel electrode

219,319,419,519: Black Matrix

221,321,421,521: gate wiring

The present invention relates to a horizontal field type liquid crystal display device, and more particularly, to a structure of a liquid crystal display device capable of preventing viewing angle crosstalk.

A liquid crystal display device is a display device that displays an image by adjusting the light transmittance of a liquid crystal by using an electric field generated by a voltage applied to a predetermined electrode, and is divided into a vertical electric field type and a horizontal electric field type according to the direction of the electric field driving the liquid crystal. .

 Twisted nematic (TN, hereinafter referred to as TN) type liquid crystal display device using a twisted nematic liquid crystal among the vertical field type liquid crystal display devices generally used is a pair of transparent electrodes in which transparent electrodes are formed to form an electric field. It consists of a substrate, a liquid crystal layer between two substrates, two polarizing plates attached to the outer surface of each substrate to polarize light, and a power supply unit capable of applying an electrical signal to each transparent electrode. Here, the electrodes formed on the lower substrate are pixel electrodes formed in units of pixels, and the electrodes formed on the upper substrate are common electrodes integrally connected to the common terminal.

When no electric field is applied to the pixel electrode and the common electrode, the liquid crystal molecules of the liquid crystal layer filled between the two substrates are parallel to the two substrates and twisted in a spiral with a constant pitch, so that the long-axis alignment orientation of the liquid crystal molecules is continuous. It has a twisted structure that changes to.

When the electric field is applied, the long-axis alignment orientation of the liquid crystal molecules is constantly arranged in parallel with the direction of the electric field to have a structure perpendicular to the two substrates.

As described above, the liquid crystal display device using the liquid crystal material has a problem in that the viewing angle is narrow and the gray level inversion occurs because the color change and the contrast ratio change depending on the angle of view of the liquid crystal panel due to the refractive index anisotropy of the liquid crystal material.

Due to these problems, the development of a liquid crystal display device having a wide viewing angle is required. Therefore, a structure of a horizontal field type liquid crystal display device, which is a new method in which a common electrode and a pixel electrode are formed on a single substrate without applying the TN method, is proposed. It became.

In the horizontal field type liquid crystal display, a liquid crystal is driven by a horizontal electric field formed between a pixel electrode and a common electrode arranged side by side on a lower substrate. The horizontal field type liquid crystal display device has a wide viewing angle of about 160 degrees. Hereinafter, the horizontal field type liquid crystal display device will be described in detail.

The horizontal field type liquid crystal display device is constituted by a thin film transistor array substrate, a color filter substrate, and liquid crystal filled between the substrates bonded to each other. The thin film transistor array substrate includes a plurality of signal wirings, thin film transistors, and alignment layers coated for liquid crystal alignment to form an electric field in a horizontal direction in each unit pixel. The color filter substrate is composed of a color filter for color implementation, a black matrix for preventing light leakage, and an alignment film coated for liquid crystal alignment.

Hereinafter, a horizontal field type liquid crystal display device of the prior art will be described in more detail with reference to the accompanying drawings.

FIG. 1A is a plan view illustrating a liquid crystal panel of a horizontal field type liquid crystal display device according to the related art, and FIG. 1B is a cross-sectional view illustrating a thin film transistor array substrate taken along the line AA ′ in FIG. 1A.

As shown in FIGS. 1A and 2B, a thin film transistor array substrate of a horizontal field type liquid crystal display device according to the related art includes a gate wiring 121, a data wiring 123, and a common wiring formed to intersect on a substrate 101. 125, a thin film transistor formed in each pixel region, and a pixel electrode 115 and a common electrode 105 formed to form a horizontal electric field in each pixel region. In this case, the semiconductor layer (123a of FIG. 1C) is formed under the gate wiring 121 in the same pattern. This is to perform a repair when the gate wiring 121 is disconnected. Although not shown in the drawings, a storage capacitor may be formed in an overlapping portion of the pixel electrode 115 and the common wiring 125 in addition to the component.

First, the wirings for supplying signals to the respective wirings will be described. The gate wiring 121 supplies a gate signal to the gate electrode 103 of the thin film transistor, and the data wiring 123 supplies the drain electrode 111b of the thin film transistor. The pixel signal is supplied to the pixel electrode 115, and the common wiring 125 supplies a reference voltage for driving the liquid crystal to the common electrode 105 with the pixel region interposed therebetween.

Next, the thin film transistor serves to keep the pixel signal of the data line 123 charged and maintained in the pixel electrode 115 in response to the gate signal of the gate line 121. ), The gate electrode 103 electrically connected to the gate electrode 103, the source electrode 111a electrically connected to the data wiring 123, the drain electrode 111b electrically connected to the pixel electrode 115, the gate electrode 103 and the gate insulating layer. The semiconductor pattern 109 forms a channel between the source electrode 111a and the drain electrode 111b while overlapping the gap 107 therebetween. In this case, the semiconductor pattern 109 is formed to overlap the data line 123, the data pad electrode (not shown), and the storage electrode (not shown), and the data line 123 is disposed on the semiconductor pattern 109. A source electrode 111a, a drain electrode 111b, a data pad electrode (not shown), a storage electrode (not shown), and an ohmic contact layer 110 for ohmic contact are further formed.

Next, the remaining components including the pixel electrode 115 will be described. The pixel electrode 115 may be electrically connected to the drain electrode 111b of the thin film transistor through a contact hole 127 penetrating through the interlayer insulating layer 113. The common electrode 105 is electrically connected to the common wiring 125 and is formed in the pixel region. A protective layer made of an insulating material may be formed on the substrate including the pixel electrode, but is omitted in the drawing.

Accordingly, a horizontal electric field is formed between the pixel electrode 115 supplied with the pixel signal through the thin film transistor and the common electrode 105 supplied with the reference voltage through the common wiring 125. The horizontal electric field causes the liquid crystal molecules arranged in the horizontal direction between the thin film transistor array substrate and the color filter array substrate to rotate by refractive anisotropy, so that the light transmittance that passes through the pixel region varies according to the degree of rotation of the liquid crystal molecules. As a result, an image is realized.

However, the conventional horizontal field liquid crystal display includes an area for displaying an abnormal screen called a light leakage area, which will be described below with reference to FIG. 1C.

FIG. 1C is a cross-sectional view taken along the line BB ′ of FIG. 1A. In the horizontal field type liquid crystal display device, the common electrode 105 and the pixel electrode 115 exist on the same substrate to form an electric field therebetween to arrange the liquid crystals 131. . In FIG. 1C, the protective layer 133, which is not shown in FIG. 1B, is illustrated. At this time, an unwanted electric field is formed not only between the common electrode 105 and the pixel electrode 115, but also between the data wiring 123 and the common electrode 105 to form an end portion of the common electrode 105 and the data wiring 123. In this adjacent portion, light 129 generated from the backlight leaks to an unwanted portion on the screen, which is called a light leakage phenomenon. In FIG. 1C, only the electric field formed between the common electrode 105 and the data wiring 123 and the arrangement of the liquid crystal 131 are drawn, but in reality, an electric field is formed between the common electrode 105 and the pixel electrode 115 and the liquid crystal is arranged. In FIG. 1C, this is omitted.

In the related art, the black matrix 119 is formed on the color filter substrate 117 to block the light leakage region. However, as shown in FIG. Although the light leakage area can be blocked, a part of the light leakage area may be observed at the side viewing angle. This phenomenon is commonly referred to as viewing angle crosstalk.

As a conventional technique for preventing the viewing angle crosstalk phenomenon, as shown in FIG. 1D, the width of the black matrix 119 is increased to cover the light leakage region, or the data electrode and the common electrode are not drawn separately. Increasing the spacing between them to reduce the foreground (disclination).

However, according to the prior arts, the viewing angle crosstalk can be prevented, but at the same time, the alignment margin of the upper and lower plates is reduced, and mis-alignment occurs during the upper and lower plates. In this case, the aperture ratio of the liquid crystal panel is reduced.

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SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. In an In-Plane Switch type liquid crystal display according to the present invention, a light leakage phenomenon is observed at a side viewing angle by extending a common electrode adjacent to a data line to a data line area. The aim is to prevent angle crosstalk.

The structure of the horizontal field type liquid crystal display device of the present invention for achieving the above object, the gate electrode and the gate wiring formed on the array substrate and a plurality of common electrodes; A gate insulating layer formed on the array substrate including the gate electrode, the gate wiring, and a plurality of common electrodes; A semiconductor layer formed on the gate insulating layer to form a semiconductor pattern; A data line defining a plurality of pixels along with the source electrode, the drain electrode, and the gate wiring formed on the semiconductor layer; An interlayer insulating layer formed on the array substrate including the source electrode, the drain electrode, and the data wiring; A plurality of pixel electrodes formed on the interlayer insulating layer and formed to form a horizontal electric field together with the plurality of common electrodes; A color filter substrate bonded to the array substrate so as to be opposite to each other; And a black matrix formed on the color filter substrate and formed in a stripe shape in a direction parallel to the gate wiring, wherein a common electrode disposed below the data wiring among the plurality of common electrodes extends toward a neighboring pixel. And overlapping the data line to block backlight light.

In this case, the common electrode may be formed in the same stacked structure as the gate electrode. The common electrode should be formed of a metal layer that can block light, such as copper (Cu) or aluminum (Al), and the area adjacent to the data electrode extends to the data wiring area so that light generated from the backlight passes through the light leakage area. Block in advance. Therefore, a part of the black matrix formed in the color filter substrate in the prior art replaces the common electrode formed in the thin film transistor array substrate.

Hereinafter, the liquid crystal display device of the present invention will be described with reference to various embodiments.

First, a first embodiment of the present invention will be described with reference to FIGS. 2A to 2C.

The planar structure of the liquid crystal panel constituting the liquid crystal display device of the present invention includes a gate wiring 221, a data wiring 223 and a common wiring 225 on the thin film transistor array substrate 201, as shown in FIG. A thin film transistor formed in each pixel region, and a pixel electrode 215 and a common electrode 205 formed to form a horizontal electric field in each pixel region. As shown in FIG. 2B, the structure of the thin film transistor array substrate having a cross-sectional view along the line A-A 'of FIG.

In this case, the characteristics of the planar structure may be described. The common electrode 205 formed near the data line 223 extends to the area of the data line 223, and the common electrode 205 extends beyond the adjacent data line 223. It is widely formed up to neighboring pixel areas.

A color filter substrate 217 is formed on the thin film transistor array substrate, and a black matrix 219 formed in a matrix form is formed on the color filter substrate 217 passing through an edge of each pixel.

At this time, the pattern portion in the direction parallel to the data wiring 223 of the black matrix 219 is formed to overlap with the data wiring 223, and has a line width smaller than that of the data wiring 223 and does not completely cover the data wiring 223. It is formed in the form. Alternatively, a pattern in a direction parallel to the data line 223 of the black matrix 219 may be formed to be wider than that of the data line 223. In this case, the line width is overlapped with the data line 223 to form the common electrode 205. It is characterized by not being formed wider than the width of).

In the structure of the liquid crystal display device according to the prior art, a pattern in a direction parallel to the data electrode of the black matrix formed on the color filter substrate is formed to the common electrode region adjacent to the data electrode. This is to prevent the light passing through the liquid crystal layer arranged by the abnormally formed electric field between the data wiring and the common electrode to leak out on the screen. Also, in order to prevent the viewing angle crosstalk phenomenon described above, the black matrix is formed to be wide enough to overlap a part of the common electrode.

However, in the first embodiment of the present invention, as described above, the common electrode 205 is formed to block the light leakage region, and since the light 229 supplied from the backlight is blocked from the thin film transistor array substrate, it is blacker than the conventional structure. Reducing the line width of the matrix 219 can prevent light leakage and viewing angle crosstalk.

As will be mentioned later in the effect of the invention to be described later, as in the present invention, by reducing the line width in the direction parallel to the black matrix data wiring, the alignment margin in the gate wiring direction when the thin film transistor array substrate and the color filter substrate are bonded together. An increasing effect occurs.

In the above-described first embodiment and the second embodiment to be described later, leaving the black matrix pattern in the direction parallel to the data wiring even in a narrow line width, in addition to the role of the black matrix blocking the light leakage region, This is because it also increases the contrast ratio. However, when the role of increasing the contrast ratio is not expected, it is also possible to configure the black matrix in a stripe form as in the third and fourth embodiments to be described later.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3A and 3B.

As shown in FIG. 3A, the thin film transistor array substrate of the second embodiment includes a gate wiring 321, a data wiring 323 and a common wiring 325, a thin film transistor formed in each pixel region, and a pixel transistor in each pixel region. The pixel electrode 315 and the common electrode 305 are formed to form a horizontal electric field.

At this time, the common electrode 305 adjacent to the data line 323 extends to the area of the data line 323 similarly to the first embodiment. The difference from the first embodiment is that a part of the common electrode under the data line is patterned. This can be clearly seen with reference to Fig. 3b.

The reason why a portion of the common electrode under the data wiring is patterned as described above is that the parasitic capacitance formed between the data wiring 323 and the lower common electrode 305 is reduced, so that the common wiring 325 and the data wiring 323 are reduced. This is to minimize crosstalk due to the mutual coupling of the respective applied signals.

Further, the black matrix 319 is formed on the color filter substrate 317 of the second embodiment in the same pattern as in the first embodiment. The pattern 319 of the black matrix is characterized in that the line width in the direction parallel to the data line 323 is narrower than that of the data line 323 for the same reason as in the first embodiment. The common electrode 305 may have a width not exceeding both ends.

Also in the liquid crystal panel structure of the second embodiment, the alignment margin can be increased when the upper and lower plates are bonded as in the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIGS. 4A and 4B.

As shown in FIG. 4A, the structure of the thin film transistor array substrate in the third embodiment is the same as that of the first embodiment in which the common electrode 405 formed near the data line 423 extends to the area of the data line 423. A portion of the common electrode 405 is formed beyond the data line 423 to the adjacent pixel region. This can be more clearly understood with reference to FIG. 4B.

In addition, referring to the structure of the color filter substrate 417 according to the third embodiment, the black matrix 419 is formed in a direction parallel to the gate wiring 421 formed on the thin film transistor array substrate. stripe). Even if the black matrix is formed in a stripe shape instead of a matrix shape, the light leakage region is covered by the data line 423 and the common electrode 405 formed on the thin film transistor array substrate, so that the light leakage region does not appear on the screen. Does not. However, a decrease in contrast ratio may occur in the bright room. On the other hand, when the upper and lower plates joined as the effects of the invention in the first and second embodiments, the effect of increasing the alignment margin in the gate wiring direction can be maximized.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 5A and 5B.

5A and 5B, in the structure of the thin film transistor array substrate in the fourth embodiment, a part of the common electrode 505 extends to the area of the data wiring 523 as in the second embodiment. A portion of the common electrode 505 under the data line 523 is patterned. As described above, the parasitic capacitance between the data line 523 and the common electrode 505 can be reduced by patterning the common electrode 505.

A black matrix 519 having a stripe shape, which is the same as that of the third embodiment, is formed on the color filter substrate in the fourth embodiment. Therefore, the effect of covering the light leakage region by the data wiring 523 and the common electrode 505 and maximizing the alignment margin when the upper and lower plates are bonded are the same as in the third embodiment.

According to the first, second, third and fourth embodiments of the present invention described above, the light leakage region between the data wiring and the common electrode is covered by the common electrode formed on the thin film transistor array substrate, not the black matrix formed on the color filter substrate. The problem that the light leakage phenomenon is observed at the side viewing angle which may occur in the prior art is not fundamentally generated. In addition, since the alignment margin increases when the upper and lower plates are bonded, the probability of misalignment is reduced, so that the aperture ratio of the liquid crystal panel may be reduced during misalignment.

In particular, in the liquid crystal display of the small model, the pixel per inch (PPI) increases, but there is a limit to reduction of various line widths, so that the aperture ratio is inevitable. When the present invention is applied to the small model, the aperture ratio may be compensated.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

As described above, the liquid crystal display according to the present invention extends a part of the common electrode adjacent to the data wiring to the data wiring region, thereby preventing the light leakage region between the data wiring and the common electrode from being displayed on the screen. In addition, since the light leakage region is not blocked by the black matrix formed on the color filter substrate, but is blocked by the common electrode formed on the thin film transistor array substrate, the light leakage region has an advantageous effect of preventing the viewing angle crosstalk phenomenon in which light leakage is observed at the side viewing angle.

In addition, due to the structural characteristics of the thin film transistor array substrate, since the line width in the direction parallel to the data wiring of the black matrix formed on the color filter substrate can be greatly reduced or omitted, the alignment margin increases significantly when the upper and lower plates are bonded. do. Since the increase in the alignment margin suppresses misalignment, it also has an advantageous effect of preventing the phenomenon that the aperture ratio is reduced during misalignment in the conventional structure.

Claims (10)

A gate electrode, a gate wiring, and a plurality of common electrodes formed on the array substrate; A gate insulating layer formed on the array substrate including the gate electrode, the gate wiring, and a plurality of common electrodes; A semiconductor layer formed on the gate insulating layer to form a semiconductor pattern; A data line defining a plurality of pixels along with the source electrode, the drain electrode, and the gate wiring formed on the semiconductor layer; An interlayer insulating layer formed on the array substrate including the source electrode, the drain electrode, and the data wiring; A plurality of pixel electrodes formed on the interlayer insulating layer and formed to form a horizontal electric field together with the plurality of common electrodes; A color filter substrate bonded to the array substrate so as to be opposite to each other; And A black matrix formed on the color filter substrate and formed in a stripe shape in a direction parallel to the gate wiring; And a common electrode positioned below the data line among the plurality of common electrodes extends toward a neighboring pixel to overlap the data line to block backlight light. The method of claim 1, The common electrode positioned below the data line and overlapping the data line, And a line width of the portion overlapping the data line is larger than the data line. The method of claim 1, The common electrode positioned below the data line and overlapping the data line, And a center portion of the portion overlapping the data line is cut and patterned. delete delete delete delete delete delete delete

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