JPH10274783A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device of a wide field of view capable of manufacturing without a complicated manufacturing process. SOLUTION: One pixel is divided into plural pixel electrodes, at least one pixel electrode among them is made to be a Cs-on-common structure forming an auxiliary capacity between it and a capacitive wiring 3 and at least one from among the remaining pixel electrodes is made to be Cs-on-gate structure forming an auxiliary capacity between it and a gate signal line 1. Consequently, plural areas having different auxiliary capacitive components in one pixel are provided and the field of view is made to be wide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device widely used for OA equipment, AV equipment and the like.

[0002]

2. Description of the Related Art As a liquid crystal display device, an active matrix type liquid crystal display device in which a plurality of gate signal lines and source signal lines orthogonal to each other, matrix pixel electrodes, and TFTs as switching elements are formed on a substrate is known. Are known.

FIG. 4A shows an equivalent circuit diagram of a TFT substrate used in a conventional active matrix type liquid crystal display device, and FIG. 4B shows an enlarged plan view of the TFT substrate.

In FIGS. 4A and 4B, 101 is a gate signal line, 102 is a source signal line, 103 is a capacitor wiring, 104 is a TFT, and 105 is a pixel electrode. In addition,
A liquid crystal capacitor _CLC is formed between the pixel electrode 105 and a counter electrode (not shown), and an auxiliary capacitor _CS is formed between the pixel electrode 105 and the capacitor wiring 103. The auxiliary capacitance C _S is provided to hold a voltage written to the pixel electrode 105 for a certain period. Note that since the capacitance wirings 103 are all fixed at a common potential, such a structure is called a Cs-on-Common structure.

A method for providing the auxiliary capacitance C _S is as follows.
The pixel electrode 105 is connected to the next (or previous) gate signal line 1
01 may be superimposed. Such a structure is Cs-
This is called an on-gate structure, and an equivalent circuit diagram and an enlarged plan view thereof are shown in FIGS.

A conventional general active matrix type liquid crystal display device has a structure in which a TN liquid crystal is sandwiched between two substrates. The TN liquid crystal essentially has an angle dependency of light transmittance. Have. In other words, the light transmittance when viewed from the long axis direction of the liquid crystal molecules is different from the light transmittance when viewed from the direction orthogonal thereto, and as a result, the contrast changes or the gradation is inverted depending on the viewing angle direction of the user. And other phenomena appear. Therefore, there is a problem that the viewing angle at which an optimal display is obtained is narrow.

Therefore, methods for improving the viewing angle by various methods have been conventionally studied.

Conventional methods for improving the viewing angle include a method in which a pixel is divided into a plurality of regions and a plurality of orientation controls are performed within one pixel by using a mask rubbing method, a collective rubbing method, or the like. As disclosed in Japanese Patent Application Laid-Open No. 7-36058, there is a method of performing display using a horizontal electric field.

Here, the mask rubbing method and the batch rubbing method will be described with reference to FIGS.

FIG. 6 is a flowchart showing the mask rubbing method. First, as shown in FIG.
An alignment film 111 is applied on the entire surface, and the entire surface is rubbed.

Next, as shown in FIG. 6B, a photoresist 112 is coated thereon, and is exposed and developed to expose an alignment film in only one region (for example, region A).

Subsequently, as shown in FIG.
The second rubbing is performed in a direction different from the first rubbing direction. At this time, the region A is rubbed twice, and the liquid crystal molecules in this region are aligned according to the second rubbing direction.

Further, by removing the resist film, as shown in FIG. 6D, the area A is in the second rubbing direction and the area B is in the first rubbing direction. A plurality of regions having different directions can be provided.

FIG. 7 is a flowchart showing the collective rubbing method. As shown in FIG. 7A, first, a first alignment film 113 and a second alignment film 114 having different pretilt angles are stacked on a substrate 110.

Next, as shown in FIG. 7B, a photoresist 112 is coated thereon, and is exposed and developed to form one region (for example, region A) of the second alignment film 114.
To expose.

Subsequently, as shown in FIG. 7C,
Only the second alignment film is etched using the photoresist as a mask.

Further, by removing the resist film, the first alignment film is exposed in the region A and the second alignment film is exposed in the region B, and the substrate is rubbed collectively. . Thereby, as shown in FIG. 7D, a plurality of regions having different pretilt angles can be provided in one pixel.

[0018]

However, in a method of dividing a pixel into a plurality of regions and performing a plurality of alignment controls in one pixel, mask rubbing is performed in order to perform a plurality of alignment controls in one pixel. Method, a batch rubbing method, or the like must be used, which has a problem that the manufacturing process becomes complicated.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 7-36058 has a problem that the display is darkened due to its structure in which the aperture ratio cannot be reduced. If the brightness of the backlight is increased to make the display brighter, there is a problem that the power consumption will increase this time.

The present invention has been made in view of the above-described problems, and realizes a wide viewing angle without complicating a conventional manufacturing process and without increasing power consumption or lowering luminance. It is intended to provide a liquid crystal display device capable of performing such operations.

[0021]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a plurality of gate signal lines and a plurality of source signal lines provided on a substrate so as to be orthogonal to each other; In a liquid crystal display device including a switching element provided in the vicinity of an intersection of a signal line and a pixel electrode connected to the switching element, a switching element corresponding to each intersection of the gate signal line and the source signal line is respectively provided. Two or more pixel electrodes are formed on each of the switching elements, and at least one of the plurality of pixel electrodes is formed to overlap with an adjacent gate signal line via an insulating film, and the remaining At least one of the pixel electrodes is formed so as to overlap with a capacitor wiring formed separately from the gate signal line via an insulating film. Than it is.

Therefore, it is possible to easily improve the viewing angle characteristics of the liquid crystal display device only by the conventional manufacturing process without going through a special manufacturing process.

In addition, the viewing angle characteristics can be further improved by configuring each of the pixel electrodes to have at least two regions having different alignment directions.

According to a third aspect of the present invention, there is provided a liquid crystal display device.
3. The liquid crystal display device according to claim 1, wherein a viewing angle is controlled by changing a potential of a signal applied to the capacitance wiring.

Therefore, it is not necessary to separately provide special control means for controlling the viewing angle, and the viewing angle can be easily controlled.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 1A is an equivalent circuit diagram of the liquid crystal display device in the present embodiment, and FIG. 1B is an enlarged plan view thereof. (A), (b) of FIG.
In the figure, 1 is a gate signal line, 2 is a source signal line, 3 is a capacitor wiring, 4 is a TFT, and 5 is a pixel electrode. Note that two TFTs 4 and two pixel electrodes 5 are provided in one pixel region, the TFT 4A is connected to the pixel electrode 5A, and the TFT 4B is connected to the pixel electrode 5B.

Further, the pixel electrode 5A forms an auxiliary capacitor C _SA between the capacitor wiring 3, the pixel electrode 5B forms an auxiliary capacitor C _SB between the next gate signal line 1 .
For this reason, different auxiliary capacitances are formed between the pixel electrode 5A and the pixel electrode 5B. For example, when halftone display is performed, the state of the holding voltage applied to the liquid crystal is different, and as shown in FIG. The rise of the liquid crystal molecules is different.
In FIG. 2, reference numeral 6 denotes a lower substrate, 7 denotes an upper substrate, 8 denotes liquid crystal molecules, and gate signal lines formed on the lower substrate 7;
The capacitance wiring, the pixel electrode and the like are omitted.

Therefore, liquid crystal molecules rising differently exist in one pixel region, so that the viewing angle can be wider than that of a conventional general liquid crystal display device. Further, since the liquid crystal display device of the present embodiment can be manufactured only by changing the shapes of the pixel electrode 5 and the gate electrode of the TFT 4 in the conventional manufacturing process, it is not necessary to add a new process, and the manufacturing process is not required. Is not complicated.

(Embodiment 2) In the above-described embodiment, a case where a liquid crystal display device having a wide viewing angle can be obtained without complicating the manufacturing process has been described. It is also possible to aim for a wider viewing angle.

FIG. 3 is an enlarged plan view of a liquid crystal display device according to a second embodiment of the present invention. Note that the equivalent circuit diagram of the liquid crystal display device according to the present embodiment is the same as FIG. In FIG. 3, each of the pixel electrodes 5A and 5B is divided into two regions of X and Y, but in the present embodiment, the alignment directions are reversed in the X and Y regions by using a mask rubbing method. ing.

With such a configuration, a liquid crystal display device having a wider viewing angle than the liquid crystal display device of the first embodiment can be obtained.

In this embodiment, the case where the rubbing directions are reversed in the regions X and Y in the pixel electrode has been described. However, the present invention is not limited to this. The pretilt angle may be made different.

In the two embodiments described above, the viewing angle can be controlled by adjusting the potential of the signal applied to the capacitor wiring 3 as necessary.

[0034]

As described above, according to the first aspect of the present invention,
According to the liquid crystal display device described above, two or more switching elements corresponding to each intersection of the gate signal line and the source signal line are formed, and a pixel electrode is formed in each of the switching elements. At least one of them is formed so as to overlap with an adjacent gate signal line via an insulating film, and at least one of the remaining pixel electrodes is formed via a capacitor wiring and an insulating film formed separately from the gate signal line. By being formed so as to overlap, a plurality of regions having different auxiliary capacitance components can be provided in one pixel, and an effect that a viewing angle can be widened is exerted.
Further, there is an effect that the viewing angle characteristics of the liquid crystal display device can be easily improved only by a conventional manufacturing process without performing a complicated manufacturing process such as a mask rubbing method or a batch rubbing method.

In addition, the configuration in which each of the pixel electrodes has at least two regions having different alignment directions has an effect that the viewing angle characteristics can be further improved.

According to the liquid crystal display device of the third aspect of the present invention, the viewing angle can be controlled by changing the amplitude of the signal applied to the capacitance wiring. There is no need to separately provide a simple control means, so that the viewing angle can be easily controlled.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram and an enlarged plan view showing a liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a view showing a state of alignment of liquid crystal molecules at the time of halftone display in the liquid crystal display device in FIG.

FIG. 3 is an enlarged plan view illustrating a liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram and an enlarged plan view showing a conventional liquid crystal display device.

FIG. 5 is an equivalent circuit diagram and an enlarged plan view showing a conventional liquid crystal display device.

FIG. 6 is a cross-sectional flowchart showing a mask rubbing method.

FIG. 7 is a cross-sectional flowchart showing a batch rubbing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gate signal line 2 Source signal line 3 Capacitance wiring 4 TFT 5 Pixel electrode

Claims (3)

[Claims] 1. A plurality of gate signal lines and source signal lines provided on a substrate so as to be orthogonal to each other, a switching element provided near an intersection of the gate signal line and the source signal line, and the switching element. And two or more switching elements corresponding to respective intersections of the gate signal lines and the source signal lines are formed, and a pixel electrode is formed in each of the switching elements. At least one of the plurality of pixel electrodes is formed to overlap with an adjacent gate signal line via an insulating film, and at least one of the remaining pixel electrodes is formed separately from the gate signal line. A liquid crystal display device which is formed so as to be overlapped with the formed capacitor wiring via an insulating film. 2. The liquid crystal display device according to claim 1, wherein each of said pixel electrodes has at least two regions having different alignment directions. 3. The liquid crystal display device according to claim 1, wherein a viewing angle is controlled by changing a potential of a signal applied to the capacitance wiring.