KR19990024620A - Complex field type liquid crystal display device - Google Patents

Abstract

According to an exemplary embodiment of the present invention, a multi-field liquid crystal display device includes a gate wiring and a data wiring arranged vertically and horizontally on a first substrate, a thin film transistor formed at an intersection point of the data wiring and the gate wiring, and a common wiring formed parallel to the gate wiring. At least one pair of first and second electrodes formed alternately in parallel with the data line to apply a transverse electric field, a protective film formed on the thin film transistor and the first and second electrodes, and formed on the second substrate. And a plurality of counter electrodes forming a first and second electrodes and an inclined electric field, and a liquid crystal layer formed between the first substrate and the second substrate.

Description

Complex field type liquid crystal display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite field type liquid crystal display device, and more particularly, to a composite field type liquid crystal display device having a gradient electric field formed by a substrate having two electrodes forming a transverse electric field and at least one counter electrode formed on a corresponding substrate. It is about.

In a thin film transistor-liquid crystal display device, a large area is strongly required, but there is a problem in that the contrast ratio changes depending on the viewing angle. In order to solve this problem, 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, and the like have been proposed. It is difficult to solve the problem of lowering the contrast ratio and changing color depending on the viewing angle.

In order to solve the above-mentioned problem, the liquid crystal display device of the in-plane switching mode, which is another liquid crystal display device recently proposed to realize the wide viewing angle, is JAPAN DISPLAY 92 P547, Japanese Patent Laid-Open No. 7- 36058, Japanese Patent Laid-Open No. 7-225538, ASIA DISPALY 95 P107, and the like.

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.

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 data 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 data 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, in the above-described conventional transverse electric field type liquid crystal display device, since an additional capacitance by a protective film and an additional capacitance by a gate insulating film exist between the data electrode and the common electrode, a high voltage considering the additional capacitance is required for the smooth driving of liquid crystal molecules. Should be applied to the layer. In addition, cross talk and afterimage may occur due to the electrode structure biased on the lower plate, and the transmittance decreases because the common electrode is made of the same material as the gate electrode, for example, an opaque metal such as Cr and Ta. There was a problem.

The present invention is to solve the above problems of the prior art, by forming an electrode group corresponding to the electrode on the substrate corresponding to the substrate on which at least one pair of electrodes for applying the transverse electric field is formed An object of the present invention is to provide a composite field type liquid crystal display device having a reduced driving voltage of a liquid crystal layer applying a gradient electric field between plates.

Another object of the present invention is to improve light transmittance by using the above electrode group as a transparent electrode group.

In order to achieve the above object, the transverse electric 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 formed on the gate insulating film. And an amorphous silicon layer, an impurity amorphous silicon layer formed on the amorphous silicon layer, and a source electrode and a drain electrode formed on the impurity amorphous silicon layer and connected to the data wiring and the data electrode, respectively. Further, the common electrode in the pixel is formed on the first substrate and connected to the common wiring, and 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 to prevent light leakage near the thin film transistor, the gate wiring, the data wiring, and the common wiring, and a color filter layer and an overcoat layer are sequentially formed thereon. . Subsequently, a first counter electrode is formed in a region of the substrate on which the light shielding layer is formed, a second counter electrode corresponding to the data electrode is formed in the pixel region, and a second alignment film is formed over the entire substrate. A liquid crystal layer is formed between one or two substrates.

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 cross-sectional view taken along the line BB ′ of FIG. 3.

5 is a view showing the electro-optical characteristics of the conventional single field method and the composite field method according to the present invention.

Explanation of symbols for the main parts of the drawings

103: first substrate 104: second substrate

106: light shielding layer 107: color filter layer

108: overcoat layer 110: gate electrode

111: common 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: first counter electrode 123: second counter electrode

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

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

In addition, the common electrode 111 in the pixel is formed on the first substrate and connected to the common wiring, and the data electrode 119 is formed on the gate insulating film 113 and connected to the drain electrode 118 of the thin film transistor. 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 coated on the entire substrate 103 and an orientation direction is determined.

In addition, a light blocking layer 106 is formed on the second substrate 104 to prevent light leakage near the thin film transistor, the gate wiring, the data wiring, and the common wiring, and the color filter layer 107 and the overcoat layer 108 thereon. ). Subsequently, a first counter electrode 122 made of a material such as indium tin oxide (ITO) is formed in an area of the substrate on which the light blocking layer 106 is formed, and an indium tin corresponding to the data electrode 119 is formed. A second counter electrode 123 made of a material such as oxide) is formed in the pixel area. In this case, the second counter electrode 123 is formed in the region of the substrate corresponding to the region between the neighboring data electrodes 119 formed on the first substrate 103 as shown in FIG. A complex electric field with the data electrode formed on the first substrate 103 is formed. After that, a second alignment layer (not shown) is formed and a liquid crystal is injected between the two substrates to complete the composite field type liquid crystal display device according to the present invention.

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.

5 shows the relationship between the light transmittance and the voltage of the conventional single field type liquid crystal display device and the composite field type liquid crystal display device according to the present invention. In addition to the decrease of about 0.5 to 1 Volt, the transmittance is improved (about 10 to 20%).

In the composite field type liquid crystal display device according to the present invention, not only can the driving voltage of the liquid crystal layer be lowered by forming the composite field by the electrode group applying the transverse electric field and the gradient electric field, but also the substrate corresponding to the electrode biased to one substrate The crosstalk and the afterimage can be reduced by forming them separately, and the light transmittance can be increased by using the separated electrodes as transparent electrodes.

Claims (16)

The first and second substrates, A liquid crystal composition layer formed between the first and second substrates; And a pair of electrode groups formed on the upper and lower portions of the liquid crystal composition layer and configured to apply a transverse electric field and an inclined electric field. The method of claim 1, A gate wiring and a data wiring arranged vertically and horizontally on the first substrate to define a pixel region; Common wiring arranged in the pixel region; A thin film transistor formed at an intersection of the gate wiring and the data wiring; The liquid crystal display device of claim 1, further comprising a first alignment layer formed on the first substrate. The composite field type liquid crystal display device of claim 1, wherein the electrodes formed on the liquid crystal composition layer are a plurality of common electrodes. The composite field type liquid crystal display of claim 1, wherein the electrodes formed under the liquid crystal composition layer are a plurality of data electrodes and a common electrode. The liquid crystal display of claim 2, wherein the first alignment layer is a photoreactive material or polyimide. The method of claim 1, A light blocking layer formed on the second substrate to prevent leakage of light; A color filter layer formed on the light shielding layer, An overcoat layer formed on the color filter layer; And a second alignment layer formed on the second substrate. The liquid crystal display of claim 3, wherein one of the plurality of common electrodes is formed on the light blocking layer region. 4. The liquid crystal display of claim 3, wherein at least one of the plurality of common electrodes is formed on a pixel area. The liquid crystal display of claim 8, wherein at least one common electrode formed on the pixel region is formed in a region corresponding to a region between neighboring data electrodes formed on a first substrate. The liquid crystal display of claim 3, wherein the plurality of common electrodes is indium tin oxide (ITO). The first and second substrates, A liquid crystal composition layer formed between the first and second substrates; A plurality of data electrodes and first common electrodes formed on the first substrate to form a transverse electric field; And a plurality of second common electrodes formed on the second substrate to form an inclined electric field with the electrodes on the first substrate. The method of claim 11, A gate wiring and a data wiring arranged vertically and horizontally on the first substrate to define a pixel region; Common wiring arranged in the pixel region; A thin film transistor formed at an intersection of the gate wiring and the data wiring; And a first alignment layer formed on the plurality of data electrodes and the common electrode. The method of claim 11, A light blocking layer formed on the second substrate to prevent leakage of light; A color filter layer formed on the light shielding layer, An overcoat layer formed on the color filter layer, and And a second alignment layer formed on the plurality of second common electrodes. The liquid crystal display of claim 11, wherein the plurality of second common electrodes is indium tin oxide (ITO). 12. The liquid crystal display device of claim 11, wherein one of the plurality of second common electrodes is formed on the light blocking layer region of claim 13. The liquid crystal display device of claim 12 or 13, wherein the first or second alignment layer is a photoreactive material or polyimide.