KR100282330B1 - In plane switching mode liquid crystal display device having electrode structre applying inclined electric field - Google Patents

Abstract

According to an aspect of the present invention, there is provided a liquid crystal display device according to an embodiment of the present invention, including a gate wiring and a data wiring arranged vertically and horizontally on a first substrate, a thin film transistor formed at the intersection of the data wiring and the gate wiring, and alternately formed in parallel with the data wiring. A plurality of data electrodes, a passivation layer formed on the thin film transistor, the common electrode and the data electrode, a common wiring formed on the second substrate, and connected to the common wiring and formed in parallel with the data wiring of the first substrate. And a plurality of common electrodes for applying a lateral gradient electric field, and a liquid crystal layer formed between the first substrate and the second substrate.

Description

Transverse gradient field type liquid crystal display device {IN PLANE SWITCHING MODE LIQUID CRYSTAL DISPLAY DEVICE HAVING ELECTRODE STRUCTRE APPLYING INCLINED ELECTRIC FIELD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transverse gradient field type liquid crystal display device, and more particularly to a transverse slope field type liquid crystal display device in which a pair of electrodes forming the transverse slope field is separately formed on upper and lower substrates.

In order to improve the viewing angle characteristic of the liquid crystal display device, various liquid crystal display devices such as a twisted nematic liquid crystal display device equipped with an optical compensation plate, a multi-domain liquid crystal display device, etc. have been proposed. In such a liquid crystal display device, it is difficult to solve the problem of lowering contrast ratio and color change depending on the viewing angle.

In order to solve the above problem, in recent years, a liquid crystal display device having an in-plane switching mode, which is another liquid crystal display device, has been proposed.

1 is a plan view of a unit pixel of a conventional transverse electric field type liquid crystal display device, which is arranged on a first substrate to define a pixel area and a gate line 2 and parallel to the gate line 2 described above. The common wiring 5 arranged in the pixel, the thin film transistor arranged at the intersection of the gate wiring 2 and the data wiring 1, and the data arranged substantially parallel to the data wiring 1 in the pixel. It consists of the electrode 19 and the common electrode 11.

FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1, wherein the thin film transistor is formed on the first substrate 3 and is connected to the gate wiring 2 and the gate electrode 10. (10) a gate insulating film 13 made of a material such as SiNx or SiOx laminated on the layer, an amorphous silicon layer 15 formed on the gate insulating film 13, and an impurity amorphous silicon layer formed on the amorphous silicon layer 15 And a source electrode 17 and a drain electrode 18 formed on the impurity amorphous silicon layer 16 and connected to the heater wiring 1 and the data electrode 19, respectively. The common electrode 11 in the pixel is formed on the first substrate and connected to the common wiring, and the heater electrode 19 is formed on the gate insulating film 13 and connected to the drain electrode 18 of the thin film transistor. On the thin film transistor, the data electrode 19 and the gate insulating film 13, a protective film 20 made of a material such as SiNx or Siox is stacked over the entire substrate, and a first alignment film (not shown) is applied thereon and an orientation direction is applied thereon. This is determined.

Further, on the first substrate 3 and the second substrate 4 corresponding to the above, the light shielding layer 6 which prevents light leakage, the color filter layer 7 made of color filter elements of R, G and B and the overcoat Layers 8 are stacked in sequence.

However, the conventional transverse electric field type liquid crystal display device has an additional capacitance between the data electrode and the common electrode by the protective film and the additional capacitance by the gate insulating film. Therefore, in order to smoothly drive the liquid crystal molecules, a high driving voltage considering the additional capacitance is required. in need. In addition, the aperture ratio is lowered (30 to 35%) by the plurality of electrodes forming the transverse electric field.

In order to achieve the proper brightness, the backlight brightness must be 3000cd / m ² or higher. This influenced the electrode characteristics of the thin film transistor and caused flicker or afterimage.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and the transverse gradient field type liquid crystal display device in which at least one pair of electrodes applying the transverse gradient field is formed on the upper and lower substrates to reduce the driving voltage of the liquid crystal layer. The purpose is to provide.

Another object of the present invention is to improve the aperture ratio by using one electrode as a transparent electrode in the pair of electrodes described above.

In order to achieve the above object, the transverse slope field type liquid crystal display device according to the present invention comprises a gate electrode formed on a first substrate and connected to the gate wiring, a gate insulating film stacked on the gate electrode, and on the gate insulating film. The formed amorphous silicon layer, the impurity amorphous silicon layer formed on the amorphous silicon layer, and the source electrode and the drain electrode formed on the impurity amorphous silicon layer and connected to the data wiring and the data electrode, respectively. The data electrode is formed on the gate insulating film and connected to the drain electrode of the thin film transistor. A protective film made of a material such as SiNx or SiOx is stacked on the thin film transistor, and a first alignment layer is coated on the entire substrate, and an orientation direction is determined.

On the second substrate corresponding to the first substrate, a light shielding layer is formed on the thin film transistor, the gate wiring, the data wiring, and the light shielding layer to prevent light leakage. The color filter layer and the overcoat layer are sequentially formed thereon. Subsequently, a plurality of common electrodes corresponding to the data electrodes are formed in the region and the pixel region of the substrate on which the light blocking layer is formed, and a second alignment layer is formed over the entire substrate, and then a liquid crystal layer is formed between the two substrates. Form.

According to another aspect of the present invention, the common electrode formed on the light shielding layer in the above structure is integrally formed to serve as the light shielding layer.

1 is a plan view of a conventional transverse electric field type liquid crystal display device.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1. FIG.

3 is a plan view of a liquid crystal display device according to the present invention;

4 is a diagram showing an embodiment of the present invention.

5 shows another embodiment of the present invention.

-Explanation of symbols for the main parts of the drawing-

103: first substrate 104: second substrate

106: light shielding layer 107: color filter layer

108: overcoat layer 110: gate electrode

113: gate insulating film 115: amorphous silicon layer

116 impurity amorphous silicon layer 117 source electrode

118: drain electrode 119: data electrode

120: protective film 122: common electrode

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

3 is a plan view of a transverse tilt field type liquid crystal display device according to the present invention, and FIGS. 4 to 5 are cross-sectional views taken along line B-B 'of FIG. 3 showing the first and second embodiments of the present invention. The liquid crystal display device of the present invention is formed of a gate electrode 110 made of an opaque metal such as Ta formed on the substrate 103 and connected to the gate wiring, and a gate made of a material such as SiNx or SiOx stacked on the gate electrode 110. On the insulating film 113, the amorphous silicon layer 115 formed on the gate insulating film 113, the impurity amorphous silicon layer 116 formed on the amorphous silicon layer 115, and the impurity amorphous silicon layer 116. And a source electrode 117 and a drain electrode 118 which are formed and connected to the data wiring and the data electrode 119, respectively.

In addition, a passivation layer 120 made of a material such as SiNx or SiOx is stacked on the thin film transistor, and a first alignment layer (not shown) is applied to the entire substrate 103 and an orientation direction is determined.

As shown in FIG. 4, in the first embodiment of the present invention, a light shielding layer 106 made of a material such as Cr or CrOx, which prevents light from leaking near the thin film transistor, gate wiring, and data wiring on the second substrate 104. ), And the color filter layer 107 and the overcoat layer 108 are formed thereon. Subsequently, a plurality of common electrodes (dotted line display) 122 made of a material such as indium tin oxide (ITO) is formed in an area of the substrate and the pixel area where the light blocking layer 106 is formed. Thereafter, when the second alignment layer (not shown) is formed and the liquid crystal is injected between the two substrates, the transverse electric field type liquid crystal display device according to the present invention is completed.

On the other hand, as shown in Fig. 5, in the second embodiment of the present invention, the color filter layer 107 and the overcoat layer 108 are sequentially formed on the second substrate 104, and the thin film transistors, the gate wirings, and the data are sequentially formed. A common electrode 122 made of a material such as Cr or CrOx is formed to prevent light leakage near the wiring, and at the same time, a plurality of common electrodes made of the same material as the common electrode 122 are formed in the pixel region. . Thereafter, a second alignment layer (not shown) is formed and the liquid crystal is injected between the two substrates to complete the transverse tilt field type liquid crystal display device according to the present invention.

The first and second embodiments described above commonly use a phase / charge field in the light shielding layer region and a gradient electric field between the common electrode and the data electrode. According to the results of the first and second embodiments, Not only can the driving voltage of the layer be reduced by about 0.5 to 1 Volt, but also the residual current that causes afterimages in the conventional transverse electric field system can be reduced.

In addition, it was confirmed that the opening ratio was improved by about 20 to 30% as well as the driving voltage was reduced compared with the conventional single field method.

The orientation direction of the first alignment layer and the second alignment layer may be determined by applying a polyimide-based alignment layer and rubbing, or irradiating light to an optical alignment layer made of polysiloxane or polyvinyl cinnamate (PVCN) -based material. You can also decide. At this time, the irradiation of light can be performed once or more times using light that is polarized or unpolarized.

In the liquid crystal display device according to the present invention, the driving voltage of the liquid crystal layer may be lowered by forming at least one pair of electrodes on the upper and lower substrates to which the horizontal tilt electric field is applied, and the separated electrodes may be transparent. It is possible to increase the light transmittance by using the electrode, and to remove the residual image by reducing the residual current.

Claims (11)

A first substrate and a second substrate, Gate wiring and data wiring arranged vertically and horizontally on the first substrate to define a pixel region; A plurality of first electrodes formed on the first substrate, A light blocking layer formed on the second substrate; A common wiring formed on the second substrate corresponding to the pixel region; A plurality of second electrodes formed on the second substrate to form a transverse slope electric field with the first electrode, a part of which is formed on the light blocking layer region; A transverse gradient field type liquid crystal display device comprising a liquid crystal composition layer formed between the first substrate and the second substrate. The method of claim 1, A thin film transistor formed at an intersection of the gate wiring and the data wiring; And a first alignment layer formed on the first electrode. The lateral gradient field type liquid crystal display device according to claim 1, wherein the plurality of first electrodes and the second electrodes are data electrodes and common electrodes, respectively. 3. The liquid crystal display device according to claim 2, wherein the first alignment layer is a photoreactive material or polyimide. The method of claim 1, A color filter layer formed on the light shielding layer, And a second alignment layer formed on the second electrode. The transverse slope field type liquid crystal display device of claim 1, wherein the plurality of second electrodes is indium tin oxide (ITO). The liquid crystal display of claim 5, further comprising an overcoat layer formed on the color filter layer. The method of claim 1, A color filter layer formed on the second substrate; A light blocking electrode formed on the color filter layer to prevent leakage of light; And a second alignment layer formed on the light blocking electrode. The liquid crystal display device according to claim 8, further comprising an overcoat layer formed on the color filter layer. 10. The liquid crystal display device of claim 8, wherein the light blocking electrode is a common electrode. 10. The liquid crystal display device according to claim 5 or 8, wherein the second alignment layer is a photoreactive material or polyimide.

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