JPH11352512A - Wide-angle visual field liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide-angle visual field liquid crystal display device, in which light shielding areas of the direction of scanning lines are small and which is capable of suppressing delays in wirings due to parastic capacitances to be generated among the scanning lines and common electrodes and is capable of preventing reduction in contrast caused by noise electric fields to be generated from the scanning lines. SOLUTION: This device is a wide-angle visual field liquid crystal display device, which is provided with plural scanning lines 1 and signal lines 2 arranged in a matrix shape in a substrate and which has common electrodes 4, which extendedly lie roughly in parallel with the scanning lines 1 and which have combtooth-shaped projecting parts in areas enclosed by the scanning lines and the signal lines and which has pixel electrodes 3 which are formed at gaps of the combtooth-shaped projecting parts of the common electrodes which are roughly in parallel with the projecting parts and whose end parts of the sides of the common electrodes are connected with each other. In this device, the scanning lines and the common electrodes are alternately disposed roughly at constant intervals, and end parts of sides of the scanning lines of the pixel electrodes are connected with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an IPS (In-Plane Swivel) which performs display by rotating liquid crystal molecules in a plane substantially horizontal to a substrate surface.
The present invention relates to a (tching) mode wide viewing angle liquid crystal display device.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device using an active element such as a thin film transistor is characterized by being thin and lightweight, and is expected as a high quality flat panel display. Conventionally, this liquid crystal display device uses a method called a twisted nematic (TN) type in which a liquid crystal is sandwiched between two substrates on which a transparent electrode is formed and the liquid crystal is driven by a voltage applied between the transparent electrodes. Japanese Patent Publication No. 63-21907 and the like have proposed a method utilizing a horizontal electric field on the substrate surface.

In a pixel selected by a scanning signal supplied to a scanning line and a data signal supplied to a signal line, an IPS for displaying by rotating liquid crystal molecules in a plane substantially horizontal to the substrate surface. In the mode, the display is performed by rotating the liquid crystal molecules in a plane substantially horizontal to the substrate surface, so even if you move the viewpoint, you are basically looking only in the short axis direction of the liquid crystal molecules. There is no viewing angle dependence of the “standing” of liquid crystal molecules, and compared to liquid crystal display devices such as TN mode,
A wide viewing angle can be achieved.

According to this method, a liquid crystal layer is driven by using comb-shaped pixel electrodes which are intermeshed with each other, and it is difficult to increase an effective area of a light transmitting area, that is, an aperture ratio. There's a problem. Hereinafter, a conventional wide viewing angle liquid crystal display device will be described.

FIG. 7 is a view showing an example of a conventional liquid crystal display device, which is a liquid crystal display device described in Japanese Patent Application Laid-Open No. 9-15650. In this structure, two pixel electrodes 3 adjacent to each other in the direction of the signal line 2 are formed in contrast to the common electrode 4, and the structure is such that two scanning lines 1 are adjacent to each other.

Also, since one pixel electrode 3 of two elements adjacent in the direction of the signal line 2 shares one common electrode 4,
The opposing length between the common electrode 4 and the pixel electrode 3 is increased, and the storage capacity of the common electrode 4 is large, that is, the delay of the common electrode 4 is large.

Further, since the scanning line 1 and the comb-like common electrode 4 are electrically released, the electric field in the light transmitting region in the display unit is disturbed by the noise electric field generated from the scanning line 1 and the contrast is low. Between the pixel electrode 3 regions of two elements adjacent to each other in the direction of the signal line 2 while sharing the common electrode 4.
The probability of occurrence of a short circuit increases.

FIG. 8 shows a liquid crystal display device described in Japanese Patent Application Laid-Open No. 10-3092. In this structure, since the scanning lines 1 and the common electrodes 4 are alternately formed at equal intervals, one line at a time, the parasitic capacitance between the scanning lines 1 and the common electrodes 4 is reduced, and furthermore, both wirings are formed in the same layer. However, the probability of occurrence of a short circuit in the pattern between the scanning line 1 and the common electrode 4 in the manufacturing process is reduced. or,
Since a large auxiliary capacitance is formed between the common electrode 4 and the pixel electrode 3, feedthrough is reduced.

However, since the scanning line 1 and the comb-shaped pixel electrode 3 are electrically open, the noise electric field generated from the scanning line 1 disturbs the electric field in the light transmitting region in the display unit, thereby causing contrast. Becomes lower.

FIG. 9 shows a liquid crystal display device described in Japanese Patent Application Laid-Open No. 9-5793. In this structure,
Since the common electrode 4 is formed on both sides of the scanning line 1, the noise electric field generated from the scanning line 1 is almost shielded by the portion of the common electrode 4 extending on both sides of the scanning line 1.
Can reduce the decrease in contrast as seen in
When the common electrode 4 is formed on both sides of the scanning line 1, the scanning line 1
Since a total of three wirings, ie, a book and two common electrodes, are adjacent to each other, the horizontal light-shielding region is conspicuous and the display quality cannot be said to be sufficient.

The scanning line 1 and the common electrode 4 are in the same layer,
Moreover, since they are formed adjacent to each other, the parasitic capacitance generated between the scanning line 1 and the common electrode 4 increases, and the delay between the two lines increases. Further, there is a problem that the probability of occurrence of a short circuit in the pattern between the scanning line 1 and the common electrode 4 in the manufacturing process increases.

[0012]

As described above,
In a conventional liquid crystal display device, when a horizontal light-shielding region including the scanning line 1 and the common electrode 4 is formed adjacent to each other, the light-shielding region extending in the scanning line 1 direction during display is conspicuous. When the electrodes 4 are formed adjacent to each other,
The parasitic capacitance generated between the scanning line 1 and the common electrode 4 increases, and the delay of both wirings increases. When the scanning line 1 and the common electrode 4 are formed adjacent to each other, the distance between the scanning line 1 and the common electrode 4 increases. When the scanning line 1 and the comb-shaped pixel electrode 3 are electrically open, a noise electric field generated from the scanning line 1 causes a short circuit in the light transmitting region of the display unit. Since the electric field is disturbed and the contrast is reduced. Since the liquid crystal capacitance between the pixel electrode 3 and the common electrode 4 is small, if the auxiliary capacitance between the common electrode 4 and the pixel electrode 3 is not increased, the feedthrough (gate voltage Drops TF
When T is turned off, the channel charge flows into the pixel electrode or the pixel potential changes due to capacitive coupling with the gate.

An object of the present invention is to reduce a light-shielding region extending in a scanning line direction, suppress a wiring delay due to a parasitic capacitance generated between a scanning line and a common electrode, and cause a noise electric field generated from the scanning line. It is an object of the present invention to provide a wide viewing angle liquid crystal display device capable of preventing a decrease in contrast.

[0014]

The present invention comprises a plurality of scanning lines and signal lines arranged in a matrix on a substrate, and a thin film transistor at an intersection of the scanning lines and the signal lines. A region surrounded by a line and the signal line, forming at least one pixel, including a common electrode extending substantially in parallel with the scanning line and alternately arranged at substantially equal intervals with the scanning line; The common electrode has a plurality of comb-shaped protrusions extending toward the scanning line side in the pixel, and the pixel electrode formed in the pixel, when viewed from a normal direction of the substrate, In the gap between adjacent comb-shaped protrusions of the common electrode,
A wide-viewing angle liquid crystal display device formed substantially parallel to the comb-shaped protrusion and connected to each other at an end on the common electrode side, wherein the comb-shaped protrusion of the common electrode is provided. The ends of the pixel electrodes on the scanning line side, which are formed substantially in parallel with each other, are connected to each other.

Further, in the present invention, the scanning line and the common electrode are formed in the same layer by the same member, and the signal line and the pixel electrode are formed by the same member on the upper layer via an insulating film layer. It is preferable to adopt a structure formed in one layer.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the liquid crystal display device according to the present invention, a plurality of scanning lines (1 in FIG. 1) and signal lines (1 in FIG. 2), a common electrode (4 in FIG. 1) extending substantially parallel to the scanning line and having a comb-shaped projection in a region surrounded by the scanning line and the signal line. A wide viewing angle having a pixel electrode (3 in FIG. 1) formed in the gap between the comb-shaped protrusions and substantially parallel to the comb-shaped protrusion, and having the ends on the common electrode side connected to each other. In a liquid crystal display device, scanning lines and common electrodes are alternately arranged at substantially equal intervals, and ends of pixel electrodes on the scanning line side are connected to each other.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

Embodiment 1 FIGS. 1 to 3 are views for explaining a liquid crystal display device according to a first embodiment of the present invention. 1 is a plan view of the first embodiment, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a plan view showing a modification of the configuration of FIG. It is. In the first embodiment, in a pixel selected by a scanning signal supplied to a scanning line 1 and a data signal supplied to a signal line 2 in an active matrix type liquid crystal display device, the pixel substantially corresponds to the substrate surface. Display by rotating liquid crystal molecules in a horizontal plane I
The present invention relates to a PS mode wide viewing angle liquid crystal display device.

Referring to FIGS. 1 and 2, a wide viewing angle liquid crystal display device according to a first embodiment of the present invention comprises a plurality of scanning lines 1 arranged in a matrix in a transparent insulating substrate and signals. A scanning line 1 and a pixel electrode 3 are provided, and a thin film transistor is provided at an intersection of the scanning line 1 and the signal line 2. A gate electrode of the thin film transistor is a scanning line, a drain electrode is a signal line, and a source electrode is a pixel electrode. And are connected respectively.
Further, a common electrode is provided which extends in the same direction as the scanning lines and is provided with a reference potential. The scanning lines 1 and the common electrodes 4 are alternately formed one by one at substantially equal intervals. The pixel electrode is formed in a comb-like shape with the common electrode as the center toward the scanning line side when viewed from the normal direction of the transparent insulating substrate, and the comb-like end portions are connected on the scanning line 1 side. ing.

The sectional structure of the liquid crystal display device according to the present embodiment is as follows: from the lower layer, a transparent insulating substrate 7, a scanning line 1 (gate electrode), an insulating film 6, a semiconductor layer 5, a signal line 2
(The drain electrode) and the pixel electrode 3 (the source electrode), the scanning line 1 (the gate electrode) and the common electrode 4 are formed of the same member in the same layer, and the upper layer is provided with the signal through the insulating film layer. The line 2 (drain electrode) and the pixel electrode 3 (source electrode) are formed of the same material and in the same layer.

According to the pixel structure of the first embodiment, the scanning lines 1 and the common electrodes 4 are formed alternately at substantially equal intervals, one line at a time. Are formed at substantially equal intervals, so that the light-shielded area in the scanning line 1 direction is not conspicuous during display. Further, since the space between the scanning line 1 and the common electrode 4 can be widened, the delay of both wirings due to the parasitic capacitance generated between the scanning line 1 and the common electrode 4 can be reduced. An effect is obtained that the probability of occurrence of a short circuit in the pattern of the electrode 4 can be reduced.

In the present embodiment, the noise electric field generated from the scanning line 1 almost leaks to the light transmitting region of the pixel because the end of the comb-shaped pixel electrode 3 on the scanning line 1 side is connected. In this case, a prescribed electric field is applied to the light transmitting region of the pixel, so that the effect of preventing a decrease in contrast can be obtained.

Further, the shape of the comb-shaped pixel electrode 3 is shown in FIG.
By suppressing the display unevenness,
Further, a wide viewing angle liquid crystal display device having excellent image quality and reliability can be provided.

The shape of this electrode is disclosed in Japanese Patent Application Laid-Open No. H10-02676.
In the lateral electric field type liquid crystal display device using a comb-shaped pixel electrode, liquid crystal molecules are usually generated by a radial electric field generated at the tip of the comb teeth and in the vicinity of the root. It features an electrode shape that suppresses the area that rotates in the direction opposite to the direction of rotation.Specifically, the liquid crystal rotates only in the normal direction of rotation over the entire area between the parallel electrode pairs. In such a case, the initial liquid crystal orientation ΦLC and the liquid crystal drive electric field azimuth ΦE1 are defined as “45 ° ≦ ΦL with respect to a direction perpendicular to the direction in which the pair of parallel electrodes extend.
C <90 degrees and ΦLC−90 degrees <ΦE1 <90 degrees ”
Is characterized by an electrode shape satisfying the following relationship.

[Embodiment 2] FIGS. 4 to 6 are views for explaining a liquid crystal display device according to a second embodiment of the present invention. 4 is a plan view of the second embodiment, FIG. 5 is a cross-sectional view taken along the line BB of FIG. 4, and FIG. 6 is a plan view showing a modification of the configuration of FIG. It is. The second embodiment also relates to the IPS mode wide viewing angle liquid crystal display device, as in the first embodiment.

Referring to FIGS. 4 and 5, the second embodiment of the present invention will be described.
The wide viewing angle liquid crystal display device according to the embodiment of
As in the embodiment, the scanning line 1 and the common electrode 4 alternately
The pixel electrodes 3 formed at substantially equal intervals line by line and having a comb-like shape are connected at the end on the scanning line 1 side. Here, the TFT is formed substantially at the center left of the pixel.

The cross-sectional structure of the liquid crystal display device according to this embodiment is the same as in the first embodiment, except that the transparent insulating substrate 7, the scanning line 1 (gate electrode), the insulating film 6
, A semiconductor layer 5, a signal line 2 (drain electrode) and a pixel electrode 3 (source electrode).
The (gate electrode) and the common electrode 4 are formed of the same material and in the same layer, and the signal line 2 (drain electrode) and the pixel electrode 3 (source electrode) are formed of the same material on the same layer with an insulating film layer above. Is formed.

The difference between the second embodiment and the first embodiment is that, in this embodiment, the pixel electrode 3 is formed between the adjacent scanning line 1 and the common electrode 4. is there. Also in the pixel structure of the present embodiment, the scanning lines 1 and the common electrodes 4 are alternately formed at substantially equal intervals, one line at a time, and the noise electric field generated from the scanning lines 1
Has a feature that it is shielded by the connection area on the scanning line 1 side and hardly leaks into the light transmission area of the pixel,
Therefore, the same effects as in the first embodiment can be obtained.

Further, similarly to the first embodiment, a pixel structure using the technique disclosed in Japanese Patent Application Laid-Open No. 10-026767 is used in the structure of the present embodiment to suppress display unevenness. Further, a wide viewing angle liquid crystal display device having excellent image quality and reliability can be provided. FIG. 6 shows the pixel structure.

[0030]

As described above, according to the present invention,
The horizontal light-shielding region is inconspicuous, the wiring delay caused by the parasitic capacitance generated between the scanning line and the common electrode can be reduced, and the short-circuiting probability of the scanning line and the common electrode pattern in the manufacturing process is reduced. . Further, according to the present invention, since a prescribed electric field is applied to the light transmitting region of the pixel, there is an effect that a decrease in contrast can be prevented.

The reason is that, in the pixel structure of the present invention, the scanning lines and the common electrodes are alternately formed at substantially equal intervals, one line at a time, and the noise electric field generated from the scanning lines is a comb-shaped pixel electrode. Is hardly leaked into the light transmitting area of the pixel.

[Brief description of the drawings]

FIG. 1 is a plan view for explaining a configuration of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the structure of the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a plan view for explaining a configuration of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a plan view illustrating a configuration of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view for explaining a structure of a liquid crystal display device according to a second embodiment of the present invention, and is a cross-sectional view taken along line BB of FIG.

FIG. 6 is a plan view illustrating a configuration of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 7 is a plan view showing a configuration of a conventional liquid crystal display device.

FIG. 8 is a plan view illustrating a configuration of a conventional liquid crystal display device.

FIG. 9 is a plan view showing a configuration of a conventional liquid crystal display device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 scanning line 2 signal line 3 pixel electrode 4 common electrode 5 semiconductor layer 6 insulating film layer 7 transparent insulating substrate

Claims (2)

[Claims] 1. A semiconductor device comprising: a plurality of scanning lines and signal lines arranged in a matrix in a substrate; and a thin film transistor at an intersection of the scanning lines and the signal lines, wherein the thin film transistors are surrounded by the scanning lines and the signal lines. Forming at least one pixel in the region, comprising a common electrode extending substantially in parallel with the scanning line, and disposed at substantially equal intervals alternately with the scanning line; A plurality of comb-shaped protrusions extending toward the scanning line side, wherein a pixel electrode formed in the pixel is adjacent to the common electrode when viewed from a normal direction of the substrate; Formed in the gap between the protruding portions in a shape substantially parallel to the comb-shaped protruding portions, and connected to each other at an end on the common electrode side,
A wide-viewing-angle liquid crystal display device, wherein ends of the pixel electrode on the scanning line side, which are formed substantially in parallel with the comb-shaped protrusions of the common electrode, are connected to each other. Wide viewing angle liquid crystal display device. 2. The scanning line and the common electrode are formed in the same layer by the same member, and the signal line and the pixel electrode are formed in the same layer by the same member on an upper layer via an insulating film layer. 2. The wide viewing angle liquid crystal display device according to claim 1, wherein: