KR100453361B1 - Apparatus for In-Plane Switching Liquid Crystal Display - Google Patents

Abstract

The present invention discloses an in-plane switching liquid crystal display device. The disclosed in-plane switching liquid crystal display device includes an upper substrate and a lower substrate for holding a liquid crystal cell gap, an insulating film divided into a plurality of via-holes disposed on the lower substrate and exposing the lower substrate, and the division. And a common electrode and a pixel electrode disposed to face each other on both sides of adjacent insulating layers. According to the present invention, the common electrode and the pixel electrode are formed in a valley type (V-type) structure so that linear and semicircular electric fields are formed between the electrodes, thereby improving response speed, improving transmittance, improving afterimage, and viewing angle of the liquid crystal. Can be.

Description

Inplane Switching Liquid Crystal Display {Apparatus for In-Plane Switching Liquid Crystal Display}

The present invention relates to an in-plane switching liquid crystal display device, and more particularly, to an in-plane switching liquid crystal display device for achieving improved response speed, improved transmittance, improved afterimage, improved viewing angle, and the like of a liquid crystal.

As is well known, In Plane Switching Liquid Crystal Display is an electrode that drives liquid crystal molecules is formed on the same substrate to improve the viewing angle characteristics of the conventional twisted nematic mode liquid crystal display It is proposed to make.

In such an in-plane switching liquid crystal display, a plurality of gate lines and a plurality of data lines are vertically arranged on a lower substrate to form a matrix array. Each of these matrix arrays defines a unit pixel area.

FIG. 1 is a plan view showing a unit pixel area of an in-plane switching liquid crystal display device, in which a pair of gate lines 11 and data lines 13 are shown on a substrate 10. Although not shown in FIG. 1, the gate line 11 and the data line 13 are insulated with the gate insulating film interposed therebetween.

The common electrode 15 is disposed in a unit pixel area, and the pixel electrode 17 is disposed to overlap a portion of the common electrode 15 with a gate insulating film (not shown) therebetween. ) And the pixel electrode 17 overlap with each other, and a storage capacitance Cst is formed.

The thin film transistor 19 as a switching element is provided at the intersection of the gate line 11 and the data line 13, and includes a gate electrode extending from the gate line 11, a drain electrode extending from the data line 13, And a channel layer formed on the source electrode and the gate electrode extending from the pixel electrode 17. The gate line 11, the data line 13, the common electrode 15, and the pixel electrode 17 are made of metal such as aluminum.

In the in-plane switching liquid crystal display, when a scan signal is applied to the gate line 11 and a display signal is applied to the data line 13, the thin film transistor 19 is turned on. Then, the display signal is transmitted to the pixel electrode 17 through the thin film transistor 19 and the common signal is continuously applied to the common electrode 15. Thus, an electric field is formed between the common electrode 15 and the pixel electrode 17.

At this time, the electric field formed is almost parallel to the surface of the substrate so that the optical axis of the liquid crystal molecules is twisted parallel to the electric field. Accordingly, the user sees the long axis of the liquid crystal molecules in either direction, thereby improving the viewing angle of the liquid crystal display.

However, the above-described in-plane switching liquid crystal display device has a problem in that an opaque metal such as aluminum is used as the electrode material and the transmittance is low due to the limitation of the transverse electric field between the electrodes. In addition, there is a problem that the afterimage is severe due to the deterioration of the insulating film between the electrodes, and the response speed of the liquid crystal is slow due to the low electric field effect.

Thus, the in-plane switching liquid crystal display device according to the present invention was devised to solve the problems of the prior art, an object of the present invention is to improve the response speed of the liquid crystal, to improve the transmittance, to improve the afterimage, to improve the viewing angle, etc. The present invention provides an in switching liquid crystal display device.

1 is a cross-sectional view of an in-plane switching liquid crystal display according to the prior art.

2 is a plan view of an in-plane switching liquid crystal display according to Embodiment 1 of the present invention; 3 is a cross-sectional view of an in-plane switching liquid crystal display device according to Embodiment 1 of the present invention; 4 is a cross-sectional view of a pixel portion of an in-plane switching liquid crystal display according to Embodiment 1 of the present invention.

5 is a plan view of an in-plane switching liquid crystal display according to a second embodiment of the present invention. 6 is a cross-sectional view of an in-plane switching liquid crystal display according to a second embodiment of the present invention. 7 is a cross-sectional view of a pixel portion of an in-plane switching liquid crystal display according to a second exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

20; Lower substrate 22; Gate electrode

24; A gate insulating film 26; Active layer

28; Data line 28a; Source electrode

28b; Drain electrode 30; Shield

32; Common electrode 34; Pixel electrode

36; Insulating film 38; Upper board

An in-plane switching liquid crystal display device according to Embodiment 1 of the present invention for achieving the object of the present invention, the upper substrate and the lower substrate for maintaining a liquid crystal cell gap; An insulating layer disposed on the lower substrate and divided into a plurality of via via holes exposing the lower substrate; And a common electrode and a pixel electrode arranged to face each other on both sides of the divided and adjacent insulating layers.

In addition, the in-plane switching liquid crystal display device according to the second embodiment of the present invention for achieving the object of the present invention, the upper substrate and the lower substrate for maintaining a liquid crystal cell gap; An insulating layer disposed on the lower substrate and divided into a plurality of via via holes exposing the lower substrate; And a common electrode and a pixel electrode covering each of the plurality of insulating layers and disposed to face each of the adjacent insulating layers.

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

2 is a plan view of an in-plane switching liquid crystal display according to Embodiment 1 of the present invention, FIG. 3 is a cross-sectional view of an in-plane switching liquid crystal display according to Embodiment 1 of the present invention, and FIG. 4 is an embodiment of the present invention. 1 is a cross-sectional view of a pixel portion of the in-plane switching liquid crystal display device according to FIG. 1.

5 is a plan view of an in-plane switching liquid crystal display device according to a second embodiment of the present invention, FIG. 6 is a cross-sectional view of the in-plane switching liquid crystal display device according to a second embodiment of the present invention, and FIG. A cross-sectional view of a pixel portion of an in-plane switching liquid crystal display device according to a second embodiment.

As shown in FIG. 2, the in-plane switching liquid crystal display according to the first exemplary embodiment of the present invention includes a gate line 22 and a data line 28 intersecting with each other to define unit pixels, and the cross arrangement. And a thin film transistor (unsigned display) as a switching element disposed at a predetermined portion, an insulating film 36 divided into a plurality, and a common electrode 32 and a pixel electrode 34 disposed on both sides of each insulating film. have.

Meanwhile, the in-plane switching liquid crystal display according to the first exemplary embodiment of the present invention can be divided into a thin film transistor unit, a pixel unit, and a data line unit, as shown in FIG. 3.

First, the thin film transistor unit includes a gate electrode 22, a gate insulating layer 24, an active layer 26, and source / drain electrodes 28a and 28b on the lower substrate 20. The common electrode 32 and the pixel electrode 34 are disposed on both sides of the insulating film 36 divided into two parts, and the data line portion includes the data line 28, the gate insulating film 24, and the protective film 30. Consists of.

Here, the essential technical idea of the present invention is to straighten the distortion of the electric field applied to the liquid crystal by the electrodes 32 and 34 arranged to face each other on the plurality of divided insulating films 36 to thereby reduce the electric field. By increasing the optical properties such as transmittance and to improve the response speed of the liquid crystal, it will be described based on this.

As shown in FIG. 4, the pixel portion of the in-plane switching liquid crystal display according to the first exemplary embodiment of the present invention includes: an upper substrate 38 and a lower substrate 20 which maintain a constant liquid crystal cell gap l ₁ ; An insulating film 36 disposed on the lower substrate 20 and divided into a plurality of via insulating holes to partially expose the lower substrate 20; And a common electrode 32 and a pixel electrode 34 disposed on both sides of each of the insulating films 36 divided into a plurality, and disposed to face each other on both sides of the adjacent insulating films 36.

Here, the insulating film 36 is composed of a gate insulating film 24 and a protective film 30, is divided into a plurality of the lower substrate 20 is disposed. Here, in both side surfaces of each of the plurality of insulating films 36, the inner surface and the lower substrate 20 are inclined at an angle of 10 to 90 degrees. In addition, the height d ₁ of the insulating film is about 3,000 to 20,000 mm based on the upper surface of the lower substrate 20. Therefore, as described below, a valley is formed between the common electrode 32 disposed on one side of the insulating layer 36 and the pixel electrode 34 disposed to face the common electrode 32 on one side of the adjacent insulating layer. In the V-type structure, a linear electric field (shown by a dotted line) is formed between the common electrode 32 and the pixel electrode 34 when voltage is applied.

In this case, as described above, the common electrode 32 is disposed on one side of the insulating layer 36, and the pixel electrode 34 is disposed on the other side thereof, and then, on one side and the other side of the adjacent insulating layer, respectively. Since the common electrode and the pixel electrode are arranged, as a whole, the common electrode 32 and the pixel electrode 34 are disposed to face each other.

In this case, the distance w ₁ between the adjacent common electrode and the pixel electrode is 2 to 15 μm, and the liquid crystal cell gap l ₁ between the lower substrate 20 and the upper substrate 38 is the height d of the insulating film. It is preferable that a semicircular electric field (shown in dashed lines) is formed on the common electrode 32 and the pixel electrode 34 at a maximum of 6 μm including ₁ ). In addition, an insulating film is removed between the common electrode 32 and the pixel electrode 34, so that deterioration due to electric field concentration on the insulating film is reduced.

As described above, the common electrode 332 and the pixel electrode 34 are disposed to face each other on both sides of the insulating layer 36 divided into a plurality of electrodes, so that the electrodes in the valley structure when voltage is applied to the electrodes 32 and 34. A straight electric field (shown by dotted lines) is formed between (32) and 34, and a transverse electric field and a semicircular electric field (shown by broken lines) are formed thereon to operate the liquid crystal (not shown). That is, the sum of the transverse electric field and the parabolic electric field.

Meanwhile, in the in-plane switching liquid crystal display according to the second exemplary embodiment of the present invention, as shown in FIG. 5, the gate line 52 and the data line 58 intersected with each other to define unit pixels are intersected with each other. A thin film transistor (unsigned display) as a switching element disposed at an arranged portion, an insulating film 66 divided into a plurality, and a common electrode 62 and a pixel electrode 64 disposed to cover each of the insulating films 66; It is configured to include.

Meanwhile, the in-plane switching liquid crystal display according to the second exemplary embodiment of the present invention can be divided into a thin film transistor unit, a pixel unit, and a data line unit as shown in FIG. 6.

First, the thin film transistor part includes a gate electrode 52, a gate insulating film 54, an active layer 56, and source / drain electrodes 58a and 58b on a lower substrate, and the pixel part is divided into a plurality of parts. The common electrode 62 or the pixel electrode 64 is disposed on the insulating film 66, and the data line portion includes a data line 58, a gate insulating film 54, and a protective film 56.

Here, the essential technical idea of the present invention is to straighten the distortion of the electric field applied to the liquid crystal (not shown) by the common electrode 62 and the pixel electrode 64 arranged to apply a plurality of divided insulating films 66. Since the optical field such as transmittance and the response speed of the liquid crystal are improved by increasing the electric field, the description will be focused on this.

As shown in FIG. 7, the pixel portion of the in-plane switching liquid crystal display according to the second exemplary embodiment of the present invention includes an upper substrate 68 and a lower substrate 50 which maintain a constant liquid crystal cell gap l ₂ . The adjacent insulating film 66 is disposed on the lower substrate 50 and covers each of the plurality of insulating films 66 divided through the via hole partially exposing the lower substrate 50. The common electrode 62 and the pixel electrode 64 are disposed on the insulating film 66 to face each other.

Here, the insulating film 66 is composed of a gate insulating film 54 and a protective film 56, and is divided into a plurality of the lower substrate 50 is disposed. Here, in each of the insulating films 66 divided into a plurality, the inner surface and the lower substrate 50 are inclined at an angle of 10 to 90 degrees. In addition, the height d ₂ of the insulating film is about 3,000 to 20,000 mm based on the upper surface of the lower substrate 50. Accordingly, as described below, a valley type (V-type) structure is formed between the common electrode 62 disposed to apply the insulating layer 66 and the pixel electrode 64 disposed to apply the adjacent insulating layer. A linear electric field (indicated by dotted lines) is formed between the common electrode 62 and the pixel electrode 64.

At this time, as described above, the common electrode 62 is disposed to apply the insulating film 66, the pixel electrode 64 is disposed to apply the adjacent insulating film, and the common electrode ( 62 is disposed so that the common electrode 62 and the pixel electrode 64 face each other as a whole.

In this case, the distance w ₂ between the adjacent common electrode 62 and the pixel electrode 64 is set to 2 to 15 μm, and the liquid crystal cell gap l ₂ between the lower substrate 50 and the upper substrate 68. It is preferable that a semicircular electric field (shown in dashed lines) is formed on the common electrode 62 and the pixel electrode 64 to have a maximum of 6 μm including the height d ₂ of the silver insulating film. In addition, the insulating film is removed between the common electrode 62 and the pixel electrode 64, so that deterioration due to electric field concentration on the insulating film is reduced.

As described above, the common electrode 62 and the pixel electrode 64 are disposed to face each other so as to apply a plurality of insulating layers 66 as described above, so that the voltages are applied to the electrodes 62 and 64 in the valley structure. A linear electric field (shown in dashed lines) is formed between the electrodes 62 and 64, and a transverse electric field and a semicircular electric field (shown in dashed lines) are formed thereon to operate the liquid crystal (not shown). That is, the sum of the transverse electric field and the parabolic electric field.

Here, in the first and second embodiments of the present invention, the common electrode and the pixel electrode are preferably made of a transparent conductor, for example, ITO in consideration of transmittance.

On the other hand, the present invention can be applied to the vertically aligned mode (Vertically Alligned mode), of course.

In addition, to those skilled in the art in order to implement the above-described core technical idea of the present invention will be able to carry out various changes without departing from the gist of the present invention.

As described above, the in-plane switching liquid crystal display according to the present invention has the following effects.

First, since the common electrode and the pixel electrode are formed in a valley type (V type), a straight line and a semicircular electric field are formed on the upper portion thereof, thereby improving the response speed and wide viewing angle of the liquid crystal.

Second, since the insulating film is removed between the common electrode and the pixel electrode, deterioration caused by the concentration of an electric field on the insulating film is minimized to improve afterimages.

Third, the transmittance is improved by configuring the common electrode and the pixel electrode with a transparent conductor.

Fourth, since the transverse electric field and the semicircular electric field are simultaneously formed between the common electrode and the pixel electrode, the electric field applied to the liquid crystal can be maintained uniformly and stably, so that not only the transmittance and the viewing angle but also the color shift phenomenon can be improved.

Fifthly, the present invention can also be applied to a burettely aligned mode, and can be applied to other liquid crystal driving modes.

Claims (10)

An upper substrate and a lower substrate for maintaining a liquid crystal cell gap; An insulating layer disposed on the lower substrate and divided into a plurality of via via holes exposing the lower substrate; And And a common electrode and a pixel electrode arranged to face each other on both sides of the divided adjacent insulating layers. The method of claim 1, And said split insulating film has a height of 3,000 to 20,000 mW. The method of claim 2, The insulated switching liquid crystal display device, wherein the divided insulating layer has an inner angle of 10 to 90 degrees between both sides thereof and the lower substrate. The method of claim 1, The in-plane switching liquid crystal display device wherein the mutually facing common electrode and pixel electrode have a spacing of 2 to 15 μm. The method of claim 1, The in-plane switching liquid crystal display, characterized in that the liquid crystal cell gap is up to 6 ㎛. An upper substrate and a lower substrate for maintaining a liquid crystal cell gap; An insulating layer disposed on the lower substrate and divided into a plurality of via via holes exposing the lower substrate; And And a common electrode and a pixel electrode covering each of the plurality of insulating films and disposed to face each of the adjacent insulating films. The method of claim 6, And said split insulating film has a height of 3,000 to 20,000 mW. The method of claim 7, wherein The insulated switching liquid crystal display device, wherein the divided insulating layer has an inner angle of 10 to 90 degrees between both sides thereof and the lower substrate. The method of claim 6, The in-plane switching liquid crystal display device wherein the mutually facing common electrode and pixel electrode have a spacing of 2 to 15 μm. The method of claim 6, The in-plane switching liquid crystal display, characterized in that the liquid crystal cell gap is up to 6 ㎛.