KR101668993B1 - In Plane Switching mode Liquid Crystal Display Device - Google Patents

Abstract

The present invention provides a liquid crystal display comprising: a gate line and a common line alternately arranged in a first direction on a substrate; A date line arranged on the substrate in a second direction different from the first direction; A thin film transistor formed in a region where the gate line and the data line cross each other; A common electrode connected to the common line; And a pixel electrode connected to the thin film transistor, wherein the common electrode and the pixel electrode are alternately arranged in parallel in the first direction. The transverse electric field type liquid crystal display device according to claim 1,

According to the present invention, the electric field direction generated in the vicinity of the data line and the initial alignment direction of the liquid crystal, that is, the rubbing direction of the alignment film are made to coincide with each other, and accordingly the liquid crystal layer located near the data line, The light leakage can be prevented in the vicinity of the data line. Since the light leakage is prevented in the lower substrate, the width of the light shielding layer formed on the upper substrate can be reduced, thereby increasing the aperture ratio and improving the brightness of the liquid crystal display device.

Transverse electric field, aperture ratio

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device, and more particularly to a transverse electric field liquid crystal display device.

Liquid crystal display devices have a wide variety of applications ranging from notebook computers, monitors, spacecrafts and aircraft to the advantages of low power consumption and low power consumption and being portable.

The liquid crystal display device includes a lower substrate, an upper substrate, and a liquid crystal layer formed between the two substrates. The arrangement of the liquid crystal layers is adjusted according to whether an electric field is applied or not, .

Such a liquid crystal display device has been developed in various ways such as a TN (Twisted Nematic) mode, an IPS (In Plane Switching) mode and a VA (Vertical Alignment) mode according to a method of adjusting the arrangement of liquid crystal layers.

In the IPS mode, the alignment of the liquid crystal layer is adjusted through the electric field in the horizontal direction by arranging the electrodes forming the electric field in parallel on the same substrate. The IPS mode liquid crystal display device is referred to as a transverse electric field liquid crystal display Quot;

Hereinafter, a conventional transverse electric field type liquid crystal display device will be described with reference to the drawings.

1A and 1B are schematic cross-sectional views of a conventional transverse electric field type liquid crystal display device. 1A and 1B illustrate a principle of a transverse electric field type liquid crystal display device. FIG. 1A shows a state in which no electric field is applied, and FIG. 1B shows a state in which an electric field is applied.

1A and 1B, a conventional transverse electric field type liquid crystal display device includes a lower substrate 10, an upper substrate 20, and a liquid crystal layer 30 formed between both substrates 10 and 20 .

On one surface of the lower substrate 10, a common electrode 12 and a pixel electrode 14 are arranged parallel to each other at a predetermined interval in order to form an electric field in a horizontal direction.

A lower alignment layer 16 and an upper alignment layer 26 are formed on one surface of the lower substrate 10 and one surface of the upper substrate 20 for initial alignment of the liquid crystal layer 30. The lower alignment film 16 and the upper alignment film 26 are oriented in a predetermined rubbing direction.

A lower polarizer plate 18 and an upper polarizer plate 28 are formed on the other surface of the lower substrate 10 and on the other surface of the upper substrate 20, respectively. The lower polarizer plate 18 and the upper polarizer plate 28 are formed such that their optical axes are perpendicular to each other.

The principle of operation of such a transverse electric field type liquid crystal display device is as follows.

1A, if an electric field is not applied between the common electrode 12 and the pixel electrode 14, the liquid crystal layer 30 maintains an initial alignment state. At this time, the light incident from below passes through the lower polarizer plate 18, passes through the liquid crystal layer 30, is not rotated in the polarization direction, and accordingly, the optical axis of the lower polarizer plate 18 The upper polarizer 28 is not allowed to transmit. Thus, the image becomes black.

1B, when an electric field is applied between the common electrode 12 and the pixel electrode 14, the alignment state of the liquid crystal layer 30 is changed. Specifically, in the vicinity of the lower substrate 10, the liquid crystal layer 30 rotates in the electric field direction between the common electrode 12 and the pixel electrode 14. However, in the vicinity of the upper substrate 20, The liquid crystal layer 30 does not rotate. At this time, the light incident from below is transmitted through the lower polarizer plate 18 and then passes through the liquid crystal layer 30 to be rotated in the polarization direction so that the upper polarizer plate 18, in which the optical axis is orthogonal to the lower polarizer plate 18, (28). Thus, the image is in the white state.

However, such a transverse electric field type liquid crystal display device has a problem that the aperture ratio is reduced and the luminance is lowered, which will be described in detail below.

FIG. 2A is a schematic plan view of a lower substrate of a conventional transverse electric field type liquid crystal display device, and FIG. 2B is a sectional view of a conventional transverse electric field type liquid crystal display device corresponding to a cross section taken along the line I-I of FIG. 2A.

2A and 2B, a gate line 11, a data line 13, a common electrode 12, and a pixel electrode 14 are formed on a lower substrate 10.

The gate lines 11 are arranged in the horizontal direction and the data lines 13 are arranged in the vertical direction. In a region where the gate lines 11 and the data lines 13 intersect, (T) is formed.

The common electrode 12 is branched from a common line 12a arranged in a horizontal direction and the pixel electrode 14 is arranged in parallel with the common electrode 12 while being connected to the thin film transistor T .

An unexplained reference numeral 15 is an insulating layer for insulating the electrodes.

On the other hand, since the region where the image is displayed in the liquid crystal display device is a pixel region, light is emitted to regions other than the pixel region, for example, the gate line 11, the data line 13, And the light shielding layer 22 is formed on the upper substrate 20 for that purpose.

However, although the light leakage is prevented by forming the light shielding layer 22 on the upper substrate 20 as described above, the aperture ratio of the liquid crystal display device is reduced thereby causing a problem of lowering the luminance.

Particularly, in the case of the conventional transverse electric field type liquid crystal display device, light leakage occurs in the vicinity of the data line 13, and as a result, as shown in FIG. 2B, The aperture ratio of the liquid crystal display device is increased.

In other words, if an electric field is not applied between the common electrode 12 and the pixel electrode 14, the liquid crystal remains aligned in the rubbing direction and the image is black, 12 and the pixel electrode 14, the arrangement of the liquid crystal in the direction of the electric field is changed so that the black state is not maintained and light leakage occurs.

Since the data lines 12 are arranged in the same direction as the common electrodes 12 and the pixel electrodes 14, a horizontal electric field is generated in the right and left of the data lines 12 when an electric field is applied, The arrangement of the liquid crystal is changed and light leakage occurs. As described above, since the area where the data line 12 is formed is not a pixel area, it is necessary to prevent light from leaking to the area. In this way, since light leakage occurs to the right and left of the data line 12, The width of the light-shielding layer 22 must be increased as shown in FIG. 2B, thereby decreasing the aperture ratio of the liquid crystal display device, thereby lowering the luminance.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transverse electric field type liquid crystal display device having improved brightness by increasing an aperture ratio.

In order to achieve the above object, the present invention provides a semiconductor device comprising: a gate line and a common line alternately arranged in a first direction on a substrate; A date line arranged on the substrate in a second direction different from the first direction; A thin film transistor formed in a region where the gate line and the data line cross each other; A common electrode connected to the common line; And a pixel electrode connected to the thin film transistor, wherein the common electrode and the pixel electrode are alternately arranged in parallel in the first direction.

The gate lines and the common lines may be alternately arranged at equal intervals.

The data lines may be alternately arranged at a first spacing and a second spacing less than the first spacing.

Wherein an orientation film for initial alignment of the liquid crystal is formed on the substrate and the orientation film can be rubbed in a direction intersecting with a second direction which is an arrangement direction of the data lines and a rubbing direction of the orientation film is formed between the data lines May be the same as the direction of the electric field generated in the substrate.

The thin film transistor may be alternately formed on one side and the other side of the gate line.

A floating structure may be formed on the gate line so as to overlap the gate line so as to prevent light leakage. The floating structure may be formed to overlap with the pixel electrode or the common electrode in a predetermined region. .

And the pixel electrode may be formed on the common line so as to overlap the common line.

A first capacitor electrode is connected to the common line, a second capacitor electrode is connected to the pixel electrode, and the second capacitor electrode is connected to the drain electrode of the thin film transistor.

According to the present invention as described above, the following effects can be obtained.

According to the present invention, the electric field direction generated in the vicinity of the data line and the initial alignment direction of the liquid crystal, that is, the rubbing direction of the alignment film are made to coincide with each other, and accordingly the liquid crystal layer located near the data line, The light leakage can be prevented in the vicinity of the data line.

Further, according to the present invention, since the floating structure is formed so as to overlap with the gate line, light leakage can be prevented in the vicinity of the gate line.

Further, according to the present invention, since the pixel electrode or the outermost common electrode is formed so as to overlap with the common line, the light leakage can be prevented in the vicinity of the common line.

As described above, since the light leakage can be prevented in the vicinity of the data line, the gate line, and the common line of the lower substrate, the width of the light shielding layer formed on the upper substrate can be reduced to increase the aperture ratio, There is an effect that the luminance of the display device is improved.

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

3 is a schematic layout of a lower substrate of a transverse electric field type liquid crystal display device according to an embodiment of the present invention.

3, the lower substrate of the transverse electric field type liquid crystal display according to an embodiment of the present invention includes a substrate 100, a gate line 110, a common line 120, a data line 130, And thin film transistors T ₁ and T ₂ .

The gate lines 110 and the common lines 120 are arranged in a first direction, specifically, a longitudinal direction, and are alternately arranged. In particular, the gate line 110 and the common line 120 are alternately arranged at the same interval D. In addition, the gate line 110 and the common line 120 may be formed of the same material in the same layer.

The data lines 130 are arranged in a second direction different from the first direction, specifically in the horizontal direction. Accordingly, the data lines 130 intersect with the gate lines 110 and the common lines 120 arranged in the vertical direction, respectively.

In addition, the data lines 130 are alternately arranged in a first interval d1 and a second interval d2 that is smaller than the first interval d1.

As described above, the pixel area (Active Area: A / A) is formed by the combination of the two data lines 130 arranged at the first interval d1 and the gate line 110 and the common line 120 intersecting with them. ).

The thin film transistors T ₁ and T ₂ may include a gate electrode extending from the gate line 110, a semiconductor layer formed on the gate electrode, a source electrode extending from the data line 130, The thin film transistors T ₁ and T ₂ may be formed in a specific manner by referring to FIG. 5 which will be described later.

The thin film transistors T ₁ and T ₂ may include a first thin film transistor T ₁ formed on one side of the gate line 110, for example, on the left side of the gate line 110, And a second thin film transistor T ₂ formed on the other side of the gate line 110, for example, the right side of the gate line 110. The first thin film transistor T ₁ and the second thin film transistor T ₂ Are alternately formed.

There the pixel region (A / A), the common electrode and the pixel electrodes are formed, and the drain of the common electrode is connected to the common line 120, the pixel electrode and the thin film transistor (T _1, T ₂₎ Electrode. In addition, the common electrode and the pixel electrode are alternately arranged in parallel in the first direction, specifically, in the longitudinal direction. A detailed formation of the common electrode and the pixel electrode will be easily understood with reference to FIG.

On the other hand, an alignment layer for initial alignment of the liquid crystal is formed on the uppermost layer of the substrate 100. The alignment layer may be formed in a first direction that is an arrangement direction of the gate lines 110 and the common lines 120, Or rubbing in a direction forming a predetermined acute angle with the first direction. That is, the alignment layer is rubbed in the second direction which is the arrangement direction of the data lines 130, for example, the direction orthogonal to the transverse direction or the direction crossing the predetermined angle.

In the transverse electric field type liquid crystal display device according to one embodiment of the present invention, the arrangement of the liquid crystal according to whether an electric field is applied will be described below.

FIGS. 4A and 4B are schematic diagrams showing alignment states of liquid crystals according to whether an electric field is applied in a transverse electric field type liquid crystal display device according to an embodiment of the present invention. FIG. FIG. 4B shows the alignment state of the liquid crystal in the vicinity of the data line 130. FIG.

4A, when the electric field is not applied in the pixel region A / A, the liquid crystal molecules are aligned in the rubbing direction of the alignment layer of the substrate 100, for example, in the longitudinal direction However, when the electric field is applied, the long axis direction of the liquid crystal is arranged in the electric field direction between the common electrode and the pixel electrode, for example, in the horizontal direction.

However, as can be seen from FIG. 4B, in a region between the data lines 130 arranged in the vicinity of the data line 130, particularly the second gap d2, in the state where no electric field is applied, Even when the long axis direction is arranged in the rubbing direction of the orientation film of the substrate 100, for example, in the longitudinal direction, and the electric field is applied, the long axis direction of the liquid crystal is the electric field direction between the data lines 130, For example, in the longitudinal direction. Therefore, in the vicinity of the data line 130, since the liquid crystal maintains the initial alignment state irrespective of whether an electric field is applied or not, generation of light leakage can be prevented.

Also, according to the present invention, generation of light leakage in the vicinity of the gate line 110 and in the vicinity of the common line 120 can also be prevented, which will be described later.

5 is a plan view of one pixel of a lower substrate of a transverse electric field type liquid crystal display device according to an embodiment of the present invention, FIG. 6A is a sectional view of line AA of FIG. 5, And Fig. 6C is a cross-sectional view of the CC line of Fig.

5 and 6A to 6C, the gate line 110 and the common line 120 are arranged in the first direction, specifically, the longitudinal direction. 5, the gate line 110 and the common line 120 are formed in a bent shape, but the present invention is not limited thereto.

In addition, the data lines 130 are arranged in a second direction different from the first direction, specifically, in the horizontal direction. Accordingly, the data lines 130 intersect with the gate lines 110 and the common lines 120 arranged in the vertical direction, respectively.

A thin film transistor T is formed in a region where the gate line 110 and the data line 130 intersect.

The thin film transistor T includes a gate electrode 112, a semiconductor layer 115, a source electrode 132, and a drain electrode 134.

The gate electrode 112 extends from the gate line 110.

The source electrode 132 is extended from the data line 130 and the drain electrode 134 is spaced apart from the source electrode 132 by a predetermined distance. The source electrode 132 may be formed in a U-shape as shown in FIG. 5, but it is not limited thereto.

The semiconductor layer 115 is formed on the upper side of the gate electrode 112 and on the lower side of the source / drain electrodes 132 and 134, that is, between the gate electrode 112 and the source / drain electrodes 132 and 134 Lt; / RTI > In addition, the semiconductor layer 115 may extend to a region where the gate line 110 and the data line 130 are formed. 6A, the semiconductor layer 115 may be formed under the data line 130, and the semiconductor layer 115 may be formed on the gate line 110, as shown in FIG. 6B. .

A common electrode 125 is connected to the common line 120. A pixel electrode 145 is connected to a drain electrode 134 of the TFT.

The common electrode 125 and the pixel electrode 145 are alternately arranged in parallel in the first direction, specifically, the longitudinal direction. Therefore, an electric field is formed in the horizontal direction between the common electrode 125 and the pixel electrode 145 arranged in parallel, and the arrangement of the liquid crystal is changed accordingly. This is described above with reference to FIG. 4A.

Since the gate line 110 and the common line 120 are formed in a curved shape, the common electrode 125 and the pixel electrode 145 are also formed in a bent shape, but the present invention is not limited thereto.

A first capacitor electrode 121 is connected to the common line 120 and a second capacitor electrode 141 is connected to the drain electrode 134 through a predetermined contact hole. As shown in FIG. 6A, the first capacitor electrode 121 and the second capacitor electrode 141 are formed to overlap with each other, thereby forming a capacitor.

Particularly, the second capacitor electrode 141 also connects the pixel electrode 145 with the drain electrode 134. That is, the pixel electrode 145 is connected to the drain electrode 134 through the second capacitor electrode 141.

As described above with reference to FIG. 4B, in the vicinity of the data line 130, an electric field in the transverse direction is not formed but an electric field in the longitudinal direction can be formed. Therefore, even if an electric field is applied to the long axis direction of the liquid crystal arranged in the longitudinal direction in the state where the electric field is not applied, the arrangement state of the liquid crystal is not changed, and therefore, the occurrence of light leakage can be prevented.

Hereinafter, the occurrence of light leakage in the vicinity of the gate line 110 and in the vicinity of the common line 120 will be described.

5, a floating structure 135 is formed in the vicinity of the gate line 110. The floating structure 135 is formed in the upper portion of the gate line 110, The gate line 110 and the predetermined region overlap each other.

6B, a gate line 110 is formed on a substrate 100, a gate insulating film 113 is formed on the gate line 110, A semiconductor layer 115 is formed on the gate insulating layer 113 and a floating structure 135 is formed on the semiconductor layer 115.

The floating structure 135 may be formed on the left and right sides of the gate line 110 while being overlapped with the gate line 110. The floating structure 135 may be formed on the left and right sides of the floating structure (135) may be connected to each other. The floating structure 135 may be formed in a floating state without being connected to other electrodes or lines, and may be formed on the same layer as the data line 130.

A protective film 137 is formed on the floating structure 135 and a pixel electrode 145 is formed on the protective film 137. The outermost common electrode 125 may be formed on the protective layer 137 instead of the pixel electrode 145. In this case, the outermost common electrode 125 may be formed on the pixel electrode 145, And is connected to the common line 120 through a predetermined contact hole.

According to the present invention, since the floating structure 135 is formed to overlap with the gate line 110, light leakage can be prevented from occurring in the vicinity of the gate line 110. Particularly, the floating structure 135 is formed to overlap with the pixel electrode 145 in a predetermined region, thereby preventing an electric field from being generated between the pixel electrode 145 and the gate line 110. In this case, the liquid crystal in the vicinity of the gate line 110 can be kept constant regardless of the application or non-application of an electric field, and the occurrence of light leakage can be prevented.

5, the pixel electrode 145 is formed in the vicinity of the common line 120 so as to overlap with the common line 120 at a predetermined region above the common line 120 (see FIG. 5) .

6C, a common line 120 is formed on the substrate 100, and a gate insulating layer 113 and a protective layer 137 are formed on the common line 120 And a pixel electrode 145 is formed on the protective film 137. [

As described above, since the pixel electrode 145 is formed to overlap the common line 120, the generation of light leakage can be prevented in the vicinity of the common line 120. That is, if the pixel electrode 145 and the common line 120 are spaced apart from each other at a predetermined distance without overlapping, light leakage occurs in the spacing region between the pixel electrode 145 and the common line 120 However, since the pixel electrode 145 is formed to overlap with the common line 120 in the present invention, the light leakage can be prevented because no spacing region exists between the pixel electrode 145 and the common line 120.

As described above, the lower substrate of the transverse electric field type liquid crystal display device according to the embodiment of the present invention has been described. The upper substrate is formed on the lower substrate, and the liquid crystal layer is formed between the lower substrate and the upper substrate.

(R), green (G), and blue (B) light-emitting layers are formed between the light-shielding layers to prevent leakage of light to regions other than the pixel region, And an overcoat layer for substrate planarization is formed on the color filter layer.

In particular, as described above, since the generation of light leakage in the lower substrate is prevented, the entire area of the light shielding layer formed on the upper substrate can be reduced, and the aperture ratio can be increased, thereby improving the brightness.

Each of the structures described above can be patterned by various methods known in the art by various methods known in the art. Hereinafter, examples of materials and pattern forming methods of the respective structures will be described, but the present invention is not limited thereto.

The floating structure 135 may include at least one of molybdenum (Mo), aluminum (Al), aluminum (Al), and the like. And may be made of chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), or an alloy thereof. It can be composed of multiple layers.

The gate insulating layer 113 and the passivation layer 137 may be formed of a silicon oxide layer (SiOx) or a silicon nitride layer (SiNx). The gate insulating layer 113 and the passivation layer 137 may be a single layer or two or more layers.

The semiconductor layer 115 may include amorphous silicon or crystalline silicon. The semiconductor layer 115 may include an ohmic contact layer doped with impurities in a region where the source electrode 132 and the drain electrode 134 are in contact with each other.

The pixel electrode 145 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), or ZnO (Zinc Oxide), and the outermost common electrode 125 may be formed of the pixel electrode 145 ) May be made of a transparent conductive material.

Each of these structures can be patterned through a so-called photolithography process in which exposure, development, and etching are performed using a photoresist (PR). In addition to the photolithography process, a paste of a metal material may be used for screen printing, inkjet printing, gravure printing, gravure offset printing, reverse reverse printing, but may also be patterned through a printing process such as offset printing, flexo printing, or microcontact printing.

1A and 1B are schematic cross-sectional views of a conventional transverse electric field type liquid crystal display device.

FIG. 2A is a schematic plan view of a lower substrate of a conventional transverse electric field type liquid crystal display device, and FIG. 2B is a sectional view of a conventional transverse electric field type liquid crystal display device corresponding to a cross section taken along the line I-I of FIG. 2A.

3 is a schematic layout of a lower substrate of a transverse electric field type liquid crystal display device according to an embodiment of the present invention.

FIGS. 4A and 4B are schematic diagrams showing the arrangement states of liquid crystals according to whether an electric field is applied in a transverse electric field type liquid crystal display device according to an embodiment of the present invention.

5 is a plan view of one pixel of a lower substrate of a transverse electric field type liquid crystal display according to an embodiment of the present invention.

6A is a cross-sectional view taken along line A-A of FIG. 5, FIG. 6B is a cross-sectional view taken along line B-B of FIG. 5, and FIG. 6C is a cross-sectional view taken along line C-C of FIG.

DESCRIPTION OF THE REFERENCE SYMBOLS

110: gate line 120: common line

125: common electrode 130: data line

135: Floating structure 145: Pixel electrode

Claims (10)

A gate line and a common line alternately arranged at equal intervals on a boundary between a plurality of pixel regions in a vertical direction on a substrate; A data line arranged laterally on the substrate; A thin film transistor formed in a region where the gate line and the data line cross each other; A common electrode connected to the common line; A pixel electrode connected to the thin film transistor, And an orientation film which is rubbed in a rubbing direction intersecting with a lateral direction which is an arrangement direction of the data lines, The common electrode and the pixel electrode are alternately arranged in parallel in the longitudinal direction,  The data lines are alternately arranged at a first interval and a second interval smaller than the first interval, And a horizontal electric field in a horizontal direction crossing the rubbing direction by the pixel electrode and the common electrode in a region between the data line and the data line arranged at the first interval, A horizontal electric field in the same direction as the rubbing direction is provided by the adjacent data lines in the region between the data line and the data line arranged at the second interval so that the alignment direction of the liquid crystal is changed in the rubbing direction The same transverse electric field type liquid crystal display device. delete delete delete delete The method according to claim 1, Wherein the thin film transistors are alternately disposed on one side and the other side of the gate line. The method according to claim 1, And a floating structure overlapping the gate line is additionally provided on the gate line so as to prevent light leakage. 8. The method of claim 7, Wherein the floating structure overlaps the pixel electrode or the common electrode in a predetermined region. The method according to claim 1, And the pixel electrode is formed on the common line so as to overlap with the common line. The method according to claim 1, Wherein the common line is connected to a first capacitor electrode, the pixel electrode is connected to a second capacitor electrode, and the second capacitor electrode is connected to a drain electrode of the thin film transistor.

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