JP2003015146A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein the strongest requirement items such as high definition, high quality, and a high opening ratio are achieved at the same time by employing a transparent conductive film as an electrode material in a fishbone IPS. SOLUTION: The liquid crystal display device, wherein both pixel electrodes and a common electrode are formed of a transparent conductive film in a chevron, the chevron form pixel electrodes and the chevron form common electrode are alternately arranged so as to divide the pixels in the longitudinal direction of the pixels in the pixels surrounded by scanning wiring and signal wiring; and also the pixel electrode in the same pixel are connected with both ends of the pixel, respectively, and the common electrodes are connected with both ends of the pixel, respectively.

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.

[0002]

2. Description of the Related Art A liquid crystal display device is constructed, for example, by arranging two transparent insulating substrates of glass or the like at a predetermined interval and injecting the liquid crystal into the space. A polymer thin film called an alignment film is arranged between the glass substrate and the liquid crystal layer, and an alignment treatment is performed to align the liquid crystal molecules.

Liquid crystal display elements are classified into a simple matrix type and an active matrix type, depending on the driving method.
Classified into one. Of these two, the active matrix type is drawing attention especially in terms of display quality, and in the current liquid crystal display device, a typical example thereof is a thin film transistor (TFT).
Drive using is the mainstream.

In the TFT drive type liquid crystal display device, a scanning wiring group extending in the X direction and arranged in parallel in the Y direction on one glass substrate constituting the liquid crystal display element, and this scanning wiring group. Signal wiring groups that are insulated from each other and extend in the Y direction and are arranged in parallel in the X direction are formed. Each region surrounded by the scanning wiring group and the signal wiring group serves as a pixel region. A TFT is formed as an active element in the pixel area. When the scanning signal is supplied to the scanning wiring, the TFT is turned on, and the video signal from the signal wiring is supplied to the pixel electrode through the TFT. As a result, each pixel is directly driven. The scanning wirings and the signal wirings extend to the peripheral portion of the substrate to form external terminals, and a driving IC for driving each of them is externally attached to the periphery of the substrate.

TCP is mainly used as a mounting method of the driving IC.
There are implementation and FCA implementation (or COG implementation). TCP
In mounting, the drive IC is mounted on a thin polyimide flexible tape using the tape automated bonding method (TA
Tape carrier package (T
CP) is connected to the liquid crystal display element by an anisotropic conductive film (ACF). In such a mounting method, since the soft flexible tape has poor dimensional stability, it is difficult to obtain the connection accuracy, and it is extremely unsuitable for a fine pitch.

Further, peripheral circuits for forming liquid crystal display data and liquid crystal timing signals necessary for the drive ICs and transmitting them to the respective drive ICs are wired on a printed circuit board and arranged around the tape carrier package (TCP) to form a tape. A liquid crystal display device is configured by connecting to a carrier package (TCP). Therefore, the area occupied by the outside of the display area (so-called frame) of the liquid crystal display device becomes large. It should be noted that in the technology currently put into practical use, TCP mounting is limited to about 130 ppi.

On the other hand, the FCA mounting is a method in which the driving IC is directly mounted on the substrate of the liquid crystal display element without using a TCP component, and is characterized in that it can cope with a fine pitch and can have a narrow frame. .

Currently, in the case of directly connecting a drive IC to a substrate of a liquid crystal display element by FCA mounting, first, ACF (anisotropic conductive film) is applied to a portion of the substrate of the liquid crystal display element where the drive IC is bonded. After that, the electrode pattern of the liquid crystal display element and the electrode pattern of the drive IC are aligned. Then, it is pressed from the side of the driving IC with a crimping tool, and the main crimping is performed under conditions of high temperature and high pressure. Usually, the temperature at the time of main pressure bonding is about 170 ° C.

Here, in the ACF, the surface of a spherical polymer is covered with gold, and an insulating film is further coated thereon. The spherical polymer is crushed by pressure bonding, and the electrodes of the drive IC and the electrodes of the liquid crystal display element are electrically connected via gold. On the other hand, since the outermost surface of this spherical polymer is coated with an insulating layer, the polymers do not conduct with each other.

Such a liquid crystal display device is used in many products such as watches, calculators, mobile phones, notebook computers and the like by taking advantage of its features such as light weight, thin shape and low power consumption. In addition, applications for desktop personal computer monitors instead of CRTs, and even televisions are expanding. Under such circumstances, there are many demands for liquid crystal display devices in the future, but mainly three items are particularly important for future liquid crystal display devices. That is, high definition (high resolution), high image quality (wide viewing angle, color reproducibility, high contrast ratio) and high aperture ratio.
The necessity of these three items will be described below.

(1) High definition (high resolution) Most of the liquid crystal display devices currently on the market are
80-100 pixels per inch, ie 80-100p
This is the definition of pi. Here, ppi is a unit of definition and indicates the number of pixels per inch. In some LCDs for laptop computers, 15 inch UXGA (1
Proceeds up to 130 ppi (600 x 1200 pixels), and 19-20 inch UXGA (100p for monitor)
pi) are being developed one after another.

However, an art appreciation display,
Furthermore, the demand of the medical industry that wants to display radiographs and images of the endoscope during surgery on the monitor,
In particular, when considering the display of a photo quality comparable to that required in the printing industry, further definition is required. However, since the image quality is determined by the distance between the screen and the human's viewpoint, the required definition depends on the size of the screen.

[0013] For example, when a person is looking at the screen and the degree of definition in which each pixel cannot be recognized is photographic image quality, 1
A 5-inch monitor requires about 140 ppi or more (flat panel display 2000, Nikkei BP). Further, in recent years, a high-definition liquid crystal display device (20.8 inches) called 200 ppi has been prototyped from IBM. 200 ppi corresponds to the maximum resolution when the human eye sees an object at a distance of 45 cm.

(2) High image quality (wide viewing angle, color reproducibility, high contrast ratio) Similarly to the definition, the image quality needs to be improved for medical purposes, art appreciation, and Internet product browsing. . The high image quality referred to here is a high contrast ratio, color reproducibility, a wide viewing angle, and the like. Currently, the S-IPS mass-produced by Hitachi, Ltd. has a contrast ratio of 3
50: 1, 170 ° viewing angle (contrast ratio 1 at the top and bottom
It has a high color purity of 60% or more in the NTSC ratio and is said to have the highest image quality of still images, but at least an image quality equivalent to this is required.

(3) High aperture ratio The pixel pitch will become narrower as the definition becomes higher in the future. For example, at 140 ppi, the pixel pitch is about 20.
It is 0 μm. If necessary wirings and electrodes are arranged in such a minute area, the area through which light can pass is naturally reduced and the aperture ratio is lowered. The decrease in aperture ratio is a major problem directly related to the decrease in brightness.

In order to compensate the decrease in brightness due to the decrease in aperture ratio with the backlight, power consumption must be increased. The decrease in aperture ratio is a factor that also greatly affects power consumption. Again, considering the brightness and power consumption, it is necessary to increase the aperture ratio.

Considering future liquid crystal displays, the above three items are very important. Therefore, focusing on these items, the conventional liquid crystal display device is summarized.
Table 1 shows the degree of achievement of each item in each conventional technique. The ones with high achievement are indicated by ◯, those with low achievement or those not achieved are indicated by x, and those attainable with conditions are indicated by Δ. The details of each technology will be described below, but from this table, it is clear that no technology currently satisfies all three items at the same time.

[0018]

[Table 1] A typical example of the above TFT driving type liquid crystal display device is a TN type liquid crystal display device. In a TN mode liquid crystal display device, electrodes are arranged inside two substrates sandwiching a liquid crystal layer so as to cover almost one surface of a pixel, and by applying an electric field in a direction perpendicular to the substrates by these electrodes, the substrates are preliminarily obtained. The light is switched by driving the liquid crystal molecules which are twisted and twisted by 90 degrees inside. Further, the polarizing plates are arranged in a crossed Nicol pattern on the outer surfaces of the upper and lower substrates of the liquid crystal display element and are arranged so as to be normally open. That is, white display is performed when no voltage is applied, and black display is performed when a voltage is applied.

Such a TN type liquid crystal display device is mainly used for a notebook type personal computer, and an external dimension of a liquid crystal display module integrated with a liquid crystal display element, an illumination light source such as a backlight, and other optical elements. In order to reduce the size, the FCA method (or COG method) in which the driving IC is directly mounted on one substrate of the liquid crystal display element is adopted without using TCP parts. When the FCA method is adopted, it is possible to deal with the fine pitch as described above, so that it is possible to deal with the high definition of the liquid crystal display element. In addition, since the pixel electrode covering almost the entire surface of the pixel region and its counter electrode are formed of a transparent conductive film such as ITO, a high aperture ratio can be achieved.

However, in the TN type liquid crystal display device, since an image is displayed by vertically standing the liquid crystal molecules on the substrate by an electric field (longitudinal electric field) in the direction perpendicular to the substrate, the image is displayed depending on the viewing angle of the screen. There is a problem that the image quality is different, that is, the viewing angle is narrow. Further, since black is displayed by applying a voltage, the black level is poor, and the contrast ratio is not so high as about 200.

In order to solve the problems of the viewing angle and color reproducibility of the TN system, a comb-teeth electrode is used so that the generated electric field has a component that is substantially parallel to the substrate surface, and liquid crystal molecules are deposited on the substrate surface. An IPS method in which a display is made by utilizing the birefringence of a liquid crystal by rotating in a substantially parallel plane is Japanese Patent Publication No. 63-21907.
And USP 4,345,249.

In this system, the light is switched by rotating the liquid crystal molecules in the plane, so that the gradation and color tone are not inverted depending on the viewing angle of the screen, and the viewing angle is wider than that of the conventional TN system. wide. Further, because of so-called normally closing, which displays black when the voltage is off, the black level is better than in the TN method, and a high contrast ratio can be realized.

A typical structure of such an IPS type liquid crystal display device is shown in FIG. First, the common electrode 3 and the scanning wiring 4 are formed on the glass substrate 8. Next, an insulating film 7 such as SiN is formed, and the signal wiring 1 and the pixel electrode 2 are formed on the insulating film. The pixel electrode is connected to the signal wiring via the active element TFT5. Further, an insulating film 6 such as SiN is formed to serve as an electrode substrate.

On the other hand, on the counter glass substrate 9, a black matrix 24 for shielding light, an RGB color filter 23, and an overcoat film 2 for flattening them.
2 is formed to serve as a color filter substrate. An alignment film 21 for aligning liquid crystal is formed on the electrode substrate and the color filter substrate. Generally, polyimide is used for the alignment film, and the liquid crystal molecules are aligned in a specified direction by rubbing (rubbing with a cloth) or the like.

A liquid crystal display device is manufactured by assembling these two substrates, injecting the liquid crystal 20 into the space between them, and further laminating the polarizing plate 25 with a crossed Nicol so as to satisfy the condition of normally closed (black display without voltage application). Make up. The voltage is applied between the pixel electrode 2 and the common electrode 3,
The resulting electric field 26, which is substantially parallel to the substrate, drives the liquid crystal molecules in-plane to switch the light.

The IPS method having excellent viewing angle characteristics is expected as a new liquid crystal display device replacing the conventional TN method, and is an important technology for future high-definition and large-screen liquid crystal panels and liquid crystal televisions. The details of the prior art of the IPS liquid crystal display device will be described below.

S-IPS In the conventional IPS method, when the screen is viewed from an oblique direction,
There was a direction in which the color tone changed to blue and a direction in which it changed to yellow depending on the viewing angle. Therefore, a technique for improving these and further widening the viewing angle is disclosed in JP-A-11-30784.
It was published in the official gazette.

In fact, the IPS type liquid crystal display device having the dogleg-shaped electrode structure proposed here is "S-IPS".
Has been commercialized as (Hitachi, Ltd.).

In S-IPS, the comb-teeth-shaped electrodes arranged so as to divide the pixel in the minor axis direction of the pixel (usually the scanning wiring direction) are formed in a dogleg shape, so that one pixel is formed. Color change is suppressed because two domains in which liquid crystal molecules rotate in different directions when a voltage is applied are formed therein. As a result, S-IPS has achieved a contrast ratio of 350: 1, a viewing angle of 170 degrees (contrast ratio of 10: 1 or more in the upper and lower directions), and a high color purity of 60% or more in the NTSC ratio, which is the highest peak in still images. It is said that the image quality.

However, it is difficult to achieve both high definition and high aperture ratio in S-IPS. The reason will be described below.

Considering the high definition of S-IPS, the pixel pitch is naturally small. Necessary electrodes and wirings must be arranged in the reduced pixel with a small space therebetween. However, in S-IPS, since these electrodes and wirings are formed of a metal material such as chromium, light does not pass through the electrode portions, and the aperture ratio decreases greatly as the definition increases. That is, if the pixel pitch becomes smaller due to higher definition, a high aperture ratio cannot be achieved.

Further, when the resolution is increased, the aperture ratio is prioritized to reduce the number of electrodes in a pixel, for example, the number of pixel electrodes which is three in one pixel is reduced to one (two-division IPS which will be described later). In the case of), the electrode spacing, which greatly affects the driving voltage of the liquid crystal display device, is determined by the definition,
It greatly affects the production efficiency. Details will be described later.

On the other hand, in order to suppress a decrease in aperture ratio due to a reduction in pixel pitch (narrowing the comb-teeth electrode spacing), it is preferable to use a transparent conductive film such as ITO as an electrode material in S-IPS. Japanese Patent Laid-Open No. 9-61842
It is proposed in Japanese Patent Publication No. There are other similar suggestions,
All of these are limited to application to comb-teeth-shaped electrodes arranged so as to divide the pixel in the minor axis direction of the pixel (normally the scanning wiring direction). With respect to these proposals, it is certainly possible to suppress the decrease in the aperture ratio due to the pixel pitch reduction accompanying the higher definition. However, by the study of the present inventor,
It was found that side effects occur at the same time as high definition.

IT normally used as a transparent conductive material
O and the like have much poorer processing accuracy than metal electrodes. When the electrode spacing becomes very narrow due to the high definition, the processing accuracy is largely reflected in the variation in the electrode spacing.
That is, the narrower the electrode spacing, the greater the variation in the electrode spacing in the transparent conductive film having poor processing accuracy, which causes uneven brightness. As can be seen from these, in the current S-IPS, there is a trade-off relationship between high definition and high aperture ratio, and it is difficult to achieve both at the same time.

Further, the following points can be pointed out when considering the high definition from the mounting method of the driving IC. As mentioned above,
In the case of a high-definition liquid crystal display device, TCP is used to mount the driving IC.
FCA implementation is more suitable than implementation. However, it has been known that when FCA mounting is applied to the current S-IPS, luminance unevenness occurs around the liquid crystal display element. This is because the driving voltage of the current S-IPS is about 2 compared to TN.
This is because the drive IC of high output is required because it is about twice as high.

In a high-output drive IC, the heat generated from the IC itself is large, and this heat is directly transmitted to the glass substrate that is connected, and for example, the liquid crystal exceeds the Tni point (liquid crystal phase / isotropic phase transition temperature). Uneven brightness occurs. Therefore, at present, TCP mounting is adopted based on the idea of separating the driving IC of the heat generating portion from the liquid crystal display element. Current S-
In IPS, there is a problem in the mounting method, and it is difficult to achieve high definition.

Fishbone IPS (FB-IP
S) Color change is reduced by an electrode structure different from S-IPS,
A means for improving image quality is proposed in Japanese Patent Laid-Open No. 11-202323 and IDRC'97L9-L12.

The liquid crystal display device having the electrode structure shown here is a fishbone IPS (FB-IPS). In the fishbone IPS, the pixel electrode and the common electrode that faces the pixel electrode are formed into a dogleg shape, and each dogleg electrode is divided into a fishbone shape so as to be divided in the long axis direction of the pixel (usually the extending direction of the signal wiring). The structure is arranged.

In such a structure, as in the case of S-IPS, since two domains having different rotation directions of liquid crystal molecules are provided in one pixel when a voltage is applied, the viewing angle and the oblique viewing angle are different. The viewing angle characteristics such as coloring are very good and high image quality can be achieved.

There is also an advantage that S-IPS does not have. This is because unlike the S-IPS, the fishbone IPS divides the pixels along the long axis direction of the pixels.
As a result, the margin for selecting the electrode interval is wider than in S-IPS. For example, this margin is very effective for setting the liquid crystal material to be the same regardless of the definition and setting an arbitrary drive voltage by adjusting the electrode interval.

The liquid crystal material greatly affects the display characteristics of the liquid crystal display device (for example, driving voltage, holding ratio, etc.). Therefore, from the viewpoint of production efficiency, it is desirable to use the same liquid crystal material regardless of the definition of the liquid crystal display device. In such a case, a fishbone IPS having a margin in designing the electrode spacing is suitable. Further, in the fishbone IPS, it is very insensitive to the variation in the electrode spacing caused in the manufacturing process. That is, it is difficult to see the uneven brightness due to the variation in the electrode interval. This is for the following reason.

The fishbone IPS has a structure having various electrode intervals in one pixel. With such a structure, it is difficult to see the uneven brightness due to the variation in the electrode spacing that occurs when the electrode spacing is narrowed. Having a plurality of electrode intervals structurally in one pixel means having various luminances in one pixel for a certain voltage. For this reason, the luminance change due to the variation in the electrode interval generated in the manufacturing process is included in the luminance change in one pixel.

However, the above-mentioned known example (JP-A-11-202)
No. 323 and the fishbone IPS in IDRC'97L9-L12) have no description of electrode material, and no description of aperture ratio, brightness unevenness, etc.
If the pixel electrode and the common electrode are metallic materials, S-IP
Similar to S, there is a problem that the aperture ratio is significantly reduced due to the narrowing of the electrodes due to the high definition. That is, also in the fishbone IPS, there is a trade-off relationship between high definition and high aperture ratio as in the S-TFT, and they cannot be achieved at the same time.

Two-division IPS Further, in the conventional IPS structure, a liquid crystal display device (20.8 inches) which realizes high definition of 200 ppi by dividing one pixel into two by metal comb-teeth electrodes.
Was prototyped (IBM). However, in such a two-division IPS, a pixel is always divided into two at any definition, so that a high image quality and a high aperture ratio can be achieved only at a specific definition. The electrode spacing that greatly affects the drive voltage greatly depends on the definition. That is, two-part IP
In S, the lower the definition, the wider the electrode interval, so the drive voltage increases.

In order to solve this, a means for increasing the dielectric anisotropy of the liquid crystal material can be considered, but there is a limit to this, and side effects (for example, impurities) due to the increase of the dielectric anisotropy are also considered. It is easy to bring in ions). In addition, depending on the definition, preparing a liquid crystal material corresponding to each of them leads to a great decrease in production efficiency.

[0046]

In the above prior art,
High definition and high image quality required for future liquid crystal display devices,
None of the three items of high aperture ratio can be achieved at the same time (Table 1). Therefore, an object of the present invention is to provide a liquid crystal display device which can achieve all of the above three items at the same time. In addition, we have achieved higher image quality by reducing the afterimage phenomenon that greatly affects image quality.
Improving production efficiency is also an important issue.

[0047]

DISCLOSURE OF THE INVENTION The present invention provides a liquid crystal display device which solves the above problems and can achieve all three items of high definition, high image quality and high aperture ratio at the same time. .

[1] A pair of substrates, at least one of which is transparent, and a liquid crystal layer sandwiched between the pair of substrates. A plurality of scanning wirings are formed on one of the substrates, and the scanning wirings are formed in a matrix. A plurality of signal wirings, a plurality of active elements formed corresponding to respective intersections of the plurality of signal wirings and the plurality of scanning wirings, a plurality of pixel electrodes connected to the active elements, A common wire formed between each of the plurality of scan wires and a plurality of common electrodes connected to the plurality of common wires; applying a voltage between the pixel electrode and the common electrode; In a liquid crystal display device that performs display by controlling the alignment of the liquid crystal by a parallel electric field that occurs predominantly on the substrate, the pixel electrode and the common electrode are both formed in a dogleg shape by a transparent conductive film, and Scan wiring and front In the pixel surrounded by the signal wiring, the V-shaped pixel electrode and the V-shaped common electrode are alternately arranged so as to divide the pixel in the longitudinal direction of the pixel, and in the same pixel. In the liquid crystal display device, the pixel electrodes are connected to each other at both ends of the pixel, and the common electrodes are connected to each other at both ends of the pixel.

[2] A pair of substrates, at least one of which is transparent, and a liquid crystal layer sandwiched between the pair of substrates. A plurality of scanning wirings are provided on one of the pair of substrates, and a matrix is formed on these scanning wirings. A plurality of signal wirings formed in a shape, a plurality of active elements formed corresponding to respective intersections of the plurality of signal wirings and the plurality of scanning wirings, and a plurality of pixel electrodes connected to the active elements A common line formed between each of the plurality of scan lines, and a plurality of common electrodes connected to the plurality of common lines, and applying a voltage between the pixel electrode and the common electrode, In a liquid crystal display device for displaying by controlling the alignment of the liquid crystal by parallel electric fields predominantly generated on the pair of substrates, both the pixel electrode and the common electrode are formed in a transparent conductive film in a Y shape, scanning In the pixel surrounded by the wiring and the signal wiring, the Y-shaped pixel electrode and the Y-shaped common electrode are alternately arranged so as to divide the pixel in the longitudinal direction of the pixel, and in the same pixel. In the liquid crystal display device, the pixel electrodes are connected to each other at both ends of the pixel, and the common electrodes are connected to each other at both ends of the pixel.

[3] The Y-shaped pixel electrode and the Y-shaped pixel electrode
V-shaped common electrodes are formed in different layers via an insulating film, and the Y-shaped pixel electrode and the Y-shaped common electrode center line are
The above [2], which does not have a region between adjacent electrodes that overlaps in a direction perpendicular to the substrate on which the electrode group is formed.
Liquid crystal display device.

[4] The signal wiring, the scanning wiring, the common wiring, the common electrode, and the pixel electrode are formed between a liquid crystal layer and a glass substrate, of which the common electrode is another electrode group. And the wiring group, which is formed in a different layer with at least one insulating film interposed therebetween, and the common electrode is formed closest to the liquid crystal layer among the other electrode groups and the wiring group [1]. Alternatively, it is in the liquid crystal display device according to [2].

A part of the common electrode may be formed so as to overlap with the signal wiring through at least one insulating film.

In addition, at least in the region where the common electrode and the signal line overlap, a low-capacitance insulating film for reducing the capacitive load may be interposed between the common electrode and the signal line. Good.

[5] A light-shielding black matrix extending in the extending direction of the scanning wiring is formed on a substrate facing the substrate on which the electrode group and the wiring group are formed, and the signal is provided. In the liquid crystal display device, the black matrix for shading is not formed in the wiring extending direction.

[6] The liquid crystal display device according to [4], wherein a part of the common electrode is formed so as to overlap with the scanning wiring via at least one insulating film.

[7] At least in the region where the common electrode and the scanning wiring overlap, a low-capacity insulating film for reducing the capacitive load is interposed between the common electrode and the scanning wiring. The liquid crystal display device according to [4].

Further, a part of the common electrode may be simultaneously formed on both the scanning wiring and the signal wiring via at least one insulating film.

[8] At least in a region where the common electrode and the signal line overlap and in a region where the common electrode and the scanning line overlap, between the common electrode and the signal line, and The liquid crystal display device according to [7], wherein a low-capacity insulating film for reducing a capacitive load is interposed between the common electrode and the scanning wiring.

[0059]

[9] The liquid crystal display device according to [8], in which the black matrix for light shielding is not formed on the substrate facing the substrate on which the electrode group and the wiring group are formed.

[10] In the liquid crystal display device, the pixel electrode is formed in a layer farthest from the layer in which the common electrode is formed.

[11] In the liquid crystal display device, the arrangement structure of the common electrode and the pixel electrode is arranged in a pixel in an inverted state with an intersection of diagonal lines of the pixel as a center of symmetry.

[12] The common electrode and the common wiring are formed in different layers, at least one insulating film is interposed between these electrodes, and the common electrode and the common electrode are formed through a contact hole formed in the insulating film. In the above liquid crystal display device to which the wiring is connected.

[13] On the side of the substrate on which the electrode group is formed, directly below the alignment control film for aligning the liquid crystal, a flat surface for flattening a step generated in the step of forming the electrode group. In the above liquid crystal display device in which the chemical insulating film is arranged.

[14] At least one active element is formed in one pixel surrounded by the scanning wiring and the signal wiring, and the active element is made of polycrystalline silicon. It is in a liquid crystal display device.

[15] A drive IC for supplying a signal to the scanning wiring, the signal wiring, and the common wiring,
The liquid crystal display device is directly mounted on the substrate constituting the liquid crystal display device by FCA mounting.

A stress buffering material for relieving stress strain may be disposed between the drive IC and the substrate constituting the liquid crystal display device in contact with the drive IC and the substrate.

Further, it is preferable that the coefficient of thermal expansion of the material forming the drive IC and the coefficient of thermal expansion of the substrate are substantially the same.

Further, it is preferable that the drive IC is directly mounted on the substrate by using an ultraviolet curable resin without thermocompression bonding.

Furthermore, a heat insulating material or heat absorbing material for preventing heat generated by the driving IC from being conducted to the substrate may be provided between the driving IC and the substrate in contact with the driving IC.

[16] The transparent conductive film is made of indium tin oxide (ITO) or indium germanium oxide (IG).
O) and at least one of indium zinc oxide (IZO).

[17] The resolution of the liquid crystal display device is 140
The liquid crystal display device has a ppi or more.

[18] Out of the sides of the substrate constituting the liquid crystal display device, at least one or more sealing ports for injecting the liquid crystal are provided on one of the sides which are substantially orthogonal to the rubbing direction. The above liquid crystal display device is sealed with a sealing material for closing the filling port.

[0073]

BEST MODE FOR CARRYING OUT THE INVENTION By using a fishbone IPS electrode structure and a transparent conductive material as the electrode, it is possible to achieve all of high definition, high image quality and high aperture ratio required for future liquid crystal display devices. Can be achieved at the same time. This is because the use of a transparent conductive material as the electrode material of the fishbone IPS eliminates the conflicting relations of high definition and high aperture ratio.

FIG. 1 shows a typical schematic plan view of a structure of a fishbone IPS using a transparent electrode and its sectional view.

In the fishbone IPS structure, a “dogleg” pixel electrode 102 and a “dogleg” common electrode 103 are provided.
However, among the pixels surrounded by the signal wiring 101 and the scanning wiring 104, they are alternately arranged so as to be divided in the longitudinal direction of the pixel (the direction of the signal wiring 101 in FIG. 1). And
The V-shaped pixel electrodes 102 in the pixel are connected at both ends of the pixel and are connected to the signal wiring through an active element such as a thin film transistor (TFT) 105. Similarly, the V-shaped common electrodes in the pixel are connected at both ends of the pixel and integrated with the common wiring. That is, at both ends of the pixel, the common electrode 103 and the pixel electrode 102 eventually overlap each other with the insulating film 107 interposed therebetween.

In FIG. 1, the pixel electrode is superposed on the common wiring. The voltage is applied between the pixel electrode 102 and the common electrode 103, and the electric field generated here drives the liquid crystal.

Liquid crystal molecules driven by an electric field have a region where the liquid crystal molecules rotate clockwise and a region where the liquid crystal molecules rotate counterclockwise because each electrode structure has a dogleg shape.
When a positive type liquid crystal (liquid crystal having positive dielectric anisotropy) is used as the liquid crystal material, the rubbing direction is the scanning wiring 10.
4, the rubbing direction is the signal wiring 10 when a negative type liquid crystal (liquid crystal with negative dielectric anisotropy) is used.
It is a direction parallel to 1.

The presence of two regions having different driving directions of liquid crystal molecules in one pixel can reduce coloring when the liquid crystal display device is viewed from an oblique direction and can achieve a wide viewing angle. High image quality can be obtained as a display device.

There is another advantage. If the pixel pitch is made smaller for higher definition and the electrode interval is made narrower accordingly, in the conventional IPS type liquid crystal display device, unevenness in brightness occurs due to the variation in electrode interval in the display area plane. Particularly, in the case of a transparent conductive film ITO or the like, which has a poorer processing accuracy than a metal electrode such as chrome, the narrower the electrode spacing, the greater the variation in the electrode spacing, and the uneven brightness is likely to occur.

However, in the fishbone structure, as can be seen from FIG. 1, since various continuous electrode intervals are included in one pixel, the problem of uneven brightness caused by the narrowed electrode interval can be solved. . This is as described in the prior art.

As a result, the fishbone IPS can be effectively combined with the transparent conductive film, and the trade-off between high definition and high aperture ratio can be solved. Therefore, it is possible to simultaneously achieve all the demands for high definition, high aperture ratio, and high image quality required for liquid crystal display devices by using a fishbone IP using a transparent conductive film for the pixel electrode and the common electrode.
It became possible by S for the first time. Here, as the transparent conductive material, indium tin oxide (ITO), indium zinc oxide (IZO), indium germanium oxide (I
GO) and the like.

In addition, this fishbone IPS structure has an advantage that there is a margin in the design of the electrode spacing. In the conventional S-TFT and the like, the pixel is divided in the short axis direction (usually the scanning wiring direction) by the comb-teeth electrode, whereas
This is because the pixels are divided in the longitudinal direction (usually the signal wiring direction) in the fishbone structure. This is a great advantage for liquid crystal display devices.

This will be described. It has been known that the display characteristics of a liquid crystal display device largely depend on the liquid crystal material. For example, the driving voltage greatly depends on the dielectric anisotropy (Δε) of the liquid crystal. In order to stabilize the display characteristics in such a liquid crystal display device, it is desirable to use the same liquid crystal material regardless of the definition of the liquid crystal display device.
As described above, in this fishbone structure, there is a margin in the design of the electrode spacing, so the electrode spacing can be set according to the liquid crystal material, and the same liquid crystal material can be used. This greatly contributes to productivity improvement. Further, by adopting the transparent conductive film, the electrode interval can be narrowed, which greatly contributes to the reduction of driving voltage, that is, the reduction of power consumption.

Next, by further devising the electrode structure,
The means for increasing the aperture ratio of fishbone IPS were examined. Hereinafter, specific electrode structures thereof will be shown and each will be described in detail.

(1) Uppermost layer common electrode structure FIG. 2 is an explanatory diagram of the present electrode structure. Compared with the fishbone IPS structure shown in FIG. 1, the common electrode 203 is an upper layer of the pixel electrode 202 with the insulating film 206 interposed therebetween. It is a structure formed in. "The uppermost common electrode" in the sense that the common electrode 203 is formed in the uppermost layer (the layer closest to the liquid crystal layer) in the electrode group including other electrodes and wirings on the electrode substrate side.
It is called a structure. The pixel electrode and the common electrode are transparent electrodes, and the common electrode is integrated with the common wiring.

In such an electrode structure, the initial alignment direction (rubbing direction) of the liquid crystal molecules when no voltage is applied, and the noise electric field (electric field generated between the common electrode and the signal wiring or the common electrode) generated outside the display region. Electric field generated between scanning lines)
It is possible to eliminate the need for either the light-shielding black matrix in the signal wiring direction or the light-shielding black matrix in the scanning wiring direction by utilizing the above direction.

Conventionally, such a light-shielding black matrix is formed on the side of a color filter which is a counter substrate of an electrode substrate, and in a manufacturing process of a liquid crystal display device, misalignment of these substrates is caused in the liquid crystal display device. It was one of the factors that lowered the aperture ratio. Therefore, the fact that the black matrix for shading is not necessary causes a margin of superposition, which leads to the suppression of the reduction of the aperture ratio due to the misalignment of superposition. As a result, the aperture ratio of the liquid crystal display device can be improved. The reason why the black matrix for shading is unnecessary in the present electrode structure will be described below.

As can be seen from the structure shown in FIG. 2, the direction of the electric field applied between the signal wiring 201 and the common electrode 203 is parallel to the scanning wiring 204, and further between the scanning wiring 204 and the common electrode 203. The direction of the electric field applied to is parallel to the signal wiring 201. The polarizing plates are arranged in a crossed Nicol mode, and are in a normally closed mode (black display when no voltage is applied).

At this time, when a positive liquid crystal (dielectric anisotropy of liquid crystal molecules is positive (Δε> 0) is used as the liquid crystal material, the rubbing direction (the initial alignment direction of the liquid crystal molecules when no voltage is applied) is used. Coincides with the direction of the electric field generated between the signal line and the common electrode in the uppermost layer, which means that liquid crystal molecules in that region may move from their initial state. Therefore, there is no light leakage in the vicinity of the signal wiring, the self-shading effect is obtained, and the black matrix for shading in the signal wiring direction can be eliminated.

On the other hand, when the negative type liquid crystal is used, the rubbing direction (which coincides with the initial alignment direction of liquid crystal molecules when no voltage is applied) is parallel to the signal wiring (perpendicular to the scanning wiring), and this is common. It matches the direction of the electric field generated between the electrode and the scanning wiring. Therefore, liquid crystal molecules in that region do not move from the initial state, and black display is performed. Therefore, there is no light leakage in the vicinity of the scanning wiring and the self-shielding effect is achieved, and the black matrix for shading in the scanning wiring direction can be eliminated.

In particular, the scanning wiring has a greater effect on the delay of the TFT switch that causes display unevenness than the signal wiring, so that the resistance is required to be as low as possible. On the other hand, a low specific resistance material such as aluminum is used as the scanning wiring material, and the resistance is reduced by widening the wiring width.

Therefore, in the present electrode structure, the negative type liquid crystal is used, and the black matrix in the wide scanning line direction can be eliminated, as compared with the case where the positive type liquid crystal is used and the black matrix in the signal line direction is not required. It greatly contributes to the improvement of the rate.

Further, since the positive type liquid crystal and the negative type liquid crystal behave differently depending on the direction of the electric field generated in the pixel region,
The following characteristics are produced.

That is, the final transmittance is higher when the negative liquid crystal is used than when the positive liquid crystal is used. In particular, the gap between electrodes for applying a voltage becomes narrower as the definition becomes higher, and the difference is large when a transparent electrode such as ITO is used as an electrode material. Hereinafter, this point will be described.

When two kinds of different electrodes (pixel electrode and common electrode) are formed on the same substrate surface as in the present electrode structure and a voltage is applied between these electrodes, the electrodes are basically parallel to the substrate surface. A transverse electric field is generated. However, especially in the vicinity of the electrodes, the electric field applied to the liquid crystal layer does not become a uniform horizontal electric field, and at the same time, a vertical electric field component is generated. The ratio of this vertical electric field component increases as the electrode spacing decreases.

In the positive type liquid crystal, liquid crystal molecules stand up on the surface of the substrate due to this vertical electric field component. Due to the rising of the liquid crystal molecules, the effective refractive index anisotropy Δn of the liquid crystal layer changes, and the transmittance decreases due to the deviation from the optimum value of Δn.

On the other hand, in the negative type liquid crystal, since the dielectric anisotropy is negative, it is not affected by the vertical component of the electric field and the liquid crystal molecules do not rise. Therefore, the effective refractive index anisotropy Δn hardly changes, and the maximum transmittance does not decrease. Of course, when the aperture ratio decreases due to high definition,
Negative type liquid crystals are more effective than positive type liquid crystals for improving the transmittance.

Further, in the positive type liquid crystal, there are two rising directions of liquid crystal molecules due to the vertical electric field component. The rising direction is different at both ends of the electrode, and the central part of the electrode serves as the boundary. In such a case, a region where light is not transmitted is formed at the boundary, and as a result, the maximum transmittance is lower than that in the case of using the negative type liquid crystal.

In the case of a negative type liquid crystal, liquid crystal molecules do not rise up with respect to the substrate surface depending on the vertical electric field component and rotate only in a plane parallel to the substrate surface. No boundaries are created. The region where such a boundary is generated mainly occurs at the central portion of the comb-teeth electrode, and when a transparent electrode such as ITO is used as the electrode material as in the present invention, it causes a big problem of lowering the transmittance. .
Further, the narrower the electrode spacing, the larger the ratio of the vertical electric field component, and the reduction of the transmittance at this boundary becomes a major issue.

Further, in FIG. 2, the common electrode is integrated with the common wiring. However, when it is difficult to make the common wiring a transparent electrode due to wiring resistance or the like, as shown in FIG. 3, the transparent common electrode 303 in the pixel formed on the uppermost layer is a through hole (contact hole). ) 309, it may be connected to the metal common wiring 310 formed in a different layer. The metal material used for the wiring is not particularly limited as long as it has low resistance, and chromium, aluminum, copper or the like may be used.

Further, in the structure of FIG. 3, the common wiring 310
Since the scan line 304 and the scan line 304 are formed in the same layer, the common line 310 is the scan line 3 of the adjacent pixel as can be recalled from the figure.
Since it is close to 04, there is a possibility of short circuit.

In order to avoid this, in general, the common wiring 310 and the scanning wiring 304 of the adjacent pixel are designed to be widened. However, this increases the area where light cannot pass, leading to a reduction in the aperture ratio. Therefore, an electrode structure as shown in FIG. 4 is also conceivable.

The common electrode 410 is arranged at the center of the pixel,
Moreover, the V-shaped electrodes are arranged so as to be inverted with respect to the pixel center. With such a structure, it is not necessary to widen the space between the common wiring and the scanning wiring as in the structure of FIG. 3, and the region where light is not transmitted can be minimized.
Since the width of the black matrix in the scanning wiring direction can be narrowed, the aperture ratio can be improved as a result.

Further, since the common electrode portion in the central portion is wide, the accuracy of the through hole is not so required and the productivity is high.
Further, since the V-shaped electrodes are symmetrically arranged with respect to the common wiring, as a result, four regions having different liquid crystal driving directions are present in one pixel. This produces an excellent effect that the viewing angle can be widened and coloring from an oblique direction can be reduced. Note that such an electrode structure is not limited to the structure shown in FIG. 4 and can be applied to the electrode structure described below.

With the common electrode structure of the uppermost layer, a higher aperture ratio can be achieved as compared with the electrode structure of FIG. 1, and the image quality can be improved by devising the arrangement of the electrodes.

(2) Electrode Structure in which Common Electrode is Overlaid on Signal Wiring This electrode structure will be described with reference to FIG. Compared with the electrode structure shown in FIGS. 2 to 4, this electrode structure has a structure in which the common electrode formed in the uppermost layer is extended in a direction parallel to the scanning wiring and the end portion thereof is superimposed on the signal wiring. . Note that an insulating film 511 having a low dielectric constant, such as an organic insulating film, is interposed between these electrodes in order to reduce the load capacitance formed by overlapping the signal wiring and the common electrode as much as possible. Note that the common electrode and the pixel electrode may be formed of a transparent conductive material, and the common electrode may be connected to a common wiring formed of metal through a through hole, as in the above (1).

In such an electrode structure, an electric field is hardly applied and liquid crystal molecules do not move in a region where the signal wiring 501 and the common electrode 503 overlap. That is, light does not leak in this region due to the self-shielding effect. Therefore, the color filter formed on the counter substrate does not need the black matrix for light shielding in the signal wiring direction, and it is possible to suppress the decrease in the aperture ratio due to the substrate misalignment.

Further, in such an electrode structure, the aperture ratio is improved because the common electrode is wider in the direction parallel to the extending direction of the scanning wiring than in the electrode structure shown in (1) above. The improvement of the aperture ratio can be expected by these two effects.

(3) Electrode Structure in which Common Electrode is Overlaid on Scanning Wiring FIG. 6 is a schematic diagram of this electrode structure. This electrode structure is shown in Figs.
Compared with the electrode structure shown in FIG. 4, the common electrode formed in the uppermost layer is extended in the direction parallel to the signal wiring, and the end portion thereof is superposed on the scanning wiring. Note that an insulating film having a low dielectric constant is interposed between these electrodes in order to reduce the load capacitance formed by the superposition of the scanning wiring and the common electrode as much as possible. Note that the common electrode and the pixel electrode may be formed of a transparent conductive material, and the common electrode may be connected to a common wiring formed of metal through a through hole, as in the above (1).

Even in this structure, improvement of the aperture ratio can be expected. That is, considering that the signal wiring in (2) is replaced with the scanning wiring, the black matrix in the scanning wiring direction is not necessary in the color filter. Also,
For the reason described in (1) above, the black matrix in the signal wiring direction is also unnecessary. Since these two black matrices are not necessary, it is possible to greatly suppress the decrease in the aperture ratio caused by the misalignment of the substrates.

(4) Electrode Structure in which Common Electrode is Overlaid on Both Scanning Wiring and Signal Wiring This electrode structure will be described with reference to FIG. Compared with the electrode structure shown in FIGS. 2 to 4, this electrode structure stretches the uppermost common electrode in both the scanning wiring direction and the signal wiring direction, and the common electrode is superposed on both the scanning wiring and the signal wiring. It is a structure.

According to this electrode structure, the self-shading effect is provided in the region where the electrodes are overlapped, and the black matrix for shading in the scanning wiring direction and the signal wiring direction is unnecessary in the color filter. A higher aperture ratio can be expected than the structures of (2) and (3).

As in the case of (1), the common electrode and the pixel electrode may be made of a transparent conductive material, and the common electrode may be connected to a common wiring made of metal through a through hole.

In the above, the pixel electrode and the common electrode have a dogleg shape as the fishbone structure. However, the vicinity of the bent portion of the doglegged electrode is the boundary of the regions where the liquid crystal molecules rotate in different directions when an electric field is applied. As a result, a so-called reverse domain is generated, and the area becomes dark. Each common electrode and pixel electrode may have a Y-shaped structure in order to eliminate such a domain and transmit light stably in the boundary region as much as possible. As shown in FIG. 8, both the pixel electrode 802 and the common electrode 803 have a Y-shaped structure formed of a transparent conductive film. Since each electrode has a Y-shaped structure, the reverse domain is unlikely to occur in the pixel due to the generation of the electric field 22 as shown in FIG. In addition, this Y-shaped electrode structure has the above-mentioned (1) to
It can be applied to all structures of (4). The applied electrode structure is shown in FIGS.

In the electrode structures of FIGS. 2 to 11 described in the above (1) to (4), the signal wiring and the pixel electrode are formed in the same layer, but the signal wiring and the pixel electrode are shown. May be formed in a different layer via an insulating film.
When formed in the same layer, the pixel electrode and the signal wiring may be short-circuited. Therefore, considering this, for example, as shown in FIG. 14, it is possible to improve the production efficiency by forming the signal wiring and the pixel electrode in different layers.

In addition, in the pursuit of improvement in image quality, afterimages
Resolving the image sticking phenomenon is also an important issue. The afterimage / image sticking phenomenon mentioned here is a phenomenon in which, when one image is displayed for a long time and then another image is displayed, the previous image that has been displayed up to that time is simultaneously displayed.

By applying a voltage between different electrodes formed on the same substrate surface as in the fishbone IPS, an electric field almost parallel to the substrate surface is generated, which causes liquid crystal molecules to be in a plane substantially parallel to the substrate. In the IPS type liquid crystal display device that switches light by driving
It has been known that there are afterimages caused by the residual charge observed in the conventional TN method and afterimages that do not depend on these residual charges.

The afterimage / image sticking phenomenon which does not depend on the accumulated electric field is a phenomenon peculiar to the IPS system.
As disclosed in Japanese Patent Laid-Open No. 19406, the rotational torque generated by the in-plane twist deformation of liquid crystal molecules due to the application of an electric field is caused by the plastic deformation of the alignment film surface that regulates the initial alignment direction of the liquid crystal molecules. Is believed to be.

Regarding the afterimage phenomenon caused by the residual charge, the liquid crystal display element is considered to be a multi-layered dielectric, and as shown in FIG. Considering a CR equivalent circuit model consisting of C, the relaxation time constant τ (∝C × R) of the entire system is reduced,
This can be solved by making it easier for the charges accumulated in the liquid crystal display element to escape.

As a concrete means, a dielectric, that is, an insulating film, is interposed as much as possible between the pixel electrode to which the voltage is applied and the common electrode. For example, in the fishbone IPS in which the common electrode is arranged on the uppermost layer proposed by the present invention, as shown in FIG.
Is preferably in the bottom layer. In this structure, the alignment film, the liquid crystal, the alignment film, and the insulating film 3 are provided between the common electrode 3 and the pixel electrode 2.
A total of 6 layers of dielectric material are interposed.

Regarding the residual image phenomenon which does not depend on the residual charge, a means for solving it by increasing the elastic modulus of the alignment film and suppressing plastic deformation is disclosed in JP-A-10-3194.
No. 06 publication.

On the other hand, according to the study by the present inventor, the afterimage due to the plastic deformation of the surface of the alignment film is generated in the region where an extremely large electric field is applied to the liquid crystal, and the rubbing efficiency is low (the rubbing cloth hits). It was found that it occurred in the (difficult) area.

Therefore, first, based on Fishbone I
Considering the electrode structure of the PS, particularly in the structure having the Y-shaped electrode, the central portions of the Y-shaped pixel electrodes and the common electrode alternately arranged in the pixel are as shown in FIG. In the case where adjacent electrodes are formed so as to overlap with each other, the space between these electrodes is substantially the same as the insulating film 6 interposed therebetween.
Equal to the thickness of. Electric field concentration occurs in such areas,
An extremely large electric field is generated as compared with other regions in the pixel. This results in an afterimage due to plastic deformation of the surface of the alignment film.

Also, regarding this, a large electrode step is generated in the portion where these electrodes overlap. In such an area having a large step, the rubbing efficiency is lowered, and an afterimage is generated. Therefore, in the present invention, fishbone IP
In order to suppress the afterimage phenomenon without impairing the features of S, FIG.
As shown in FIG. 2A, the structure is such that the center lines of adjacent Y-shaped electrodes do not overlap.

Further, as shown in FIG. 13, the common electrode 3 formed on the uppermost layer is coated with a flattening insulating film 12 for reducing a step due to an electrode in a pixel, and is rubbed. Afterimages can also be suppressed by improving efficiency.

The effect of applying this flattening insulating film is considered to be the relaxation time τ when considering the above CR equivalent circuit model.
Is also effective in suppressing the afterimage phenomenon caused by residual charges.

Next, the high definition of the liquid crystal display device will be considered again. The high definition of a liquid crystal display device has a small pixel, and it cannot be solved even if only the problem due to the electrode configuration in the pixel is considered. It is also necessary to consider means for supplying a signal to each pixel due to high definition.

At present, a typical active matrix type liquid crystal display device uses an amorphous Si-TFT. In this case, a driving IC for driving them must be arranged and connected around the liquid crystal display element. At present, there are mainly two methods for mounting this driving IC, TCP mounting and FCA mounting.

In the TCP implementation, it is currently about 1
The limit is about 30 ppi, and FCA implementation is effective for further high definition (for example, about 140 ppi is required for displaying on a 15-inch monitor at a photo quality level).

On the other hand, there is an active matrix type liquid crystal display device using a polycrystalline Si-TFT instead of an amorphous Si-TFT. By using the polycrystalline Si-TFT, the driving circuit itself can be incorporated in the pixel. Since the drive circuit can be integrated, a high definition of, for example, 200 ppi is possible. Further, there are no restrictions on the conventional mounting technology of the drive circuit. That is, in the high-definition liquid crystal display device, the FCA mounting and the polycrystalline Si-TFT technology are effective in view of supplying and driving a signal to the electrode group of the pixel. The details of FCA implementation are described below. Along with the higher definition, the pixel pitch becomes smaller, so that the electrode wiring interval at the time of mounting also becomes narrower. T
In the CP mounting, the drive IC is wired on a flexible tape such as polyimide, so that the accuracy is not high, and 130 ppi is the limit in the technology currently put into practical use.

On the other hand, in the FCA mounting, since the driving IC is directly connected to the liquid crystal display element substrate, a fineness of 140 ppi or more can sufficiently cope. This is because the material forming the driving IC (generally Si) is also the liquid crystal display element substrate (generally SiO).
_{This is because 2} ) is also hard and does not involve a flexible tape. Further, in the liquid crystal display device mounted with FCA, there is an advantage that the cost can be reduced by not using a tape and the number of connection can be reduced, and the frame can be narrowed.

However, there is a problem that occurs because the drive IC and the substrate to be connected are hard. In the FCA mounting, after the electrode pattern of the liquid crystal display element and the electrode pattern of the driving IC are aligned as described above, a pressure bonding tool is pressed from the driving IC side and pressure bonding is performed under high temperature and high pressure conditions. Usually, the temperature during pressure bonding is about 170 ° C.

In such a case, the material forming the drive IC (generally Si) and the material forming the liquid crystal display element substrate (Si
Since the coefficient of thermal expansion of O ₂ ) is different, stress strain is generated after crimping, and the connection of the connecting portion becomes poor, so that an image cannot be displayed normally.

To solve this, (1) Drive I
Disposing a stress relaxation material between C and the liquid crystal display element substrate, (2) making the thermal expansion coefficient of the material forming the drive IC and the material of the liquid crystal display element substrate substantially the same, and (3) applying heat It was studied to connect the driving IC with an ultraviolet curable resin without using it.

By disposing the stress relaxation material in contact with the drive IC and the substrate, the stress strain generated between the drive IC and the liquid crystal display element substrate can be absorbed and the connection failure can be solved. Further, if the two materials are designed so that the coefficients of thermal expansion are almost the same, stress strain hardly occurs. Furthermore, if the ultraviolet curable resin is used and the wires are connected at room temperature without applying heat, stress strain does not occur regardless of the difference in thermal expansion coefficient between the respective materials.

There is another problem in FCA mounting other than stress and strain. The heat generated by the driving IC is directly conducted to the liquid crystal display element substrate, and the heat raises the temperature of the liquid crystal.
Brightness unevenness occurs around the liquid crystal display element, for example, when it exceeds the Tni point (liquid crystal phase / isotropic phase transition temperature). Particularly, in the current IPS liquid crystal display device, a high output driving IC is inevitably used because a high driving voltage is required. However, such a high output drive IC easily emits high heat, and brightness unevenness is remarkable around the liquid crystal display device.

For the purpose of solving this, it was examined to dispose a heat insulating material or a heat absorbing material between the drive IC and the liquid crystal display element substrate. Arrange the heat insulating material or heat absorbing material in this way,
Alternatively, by enclosing the drive IC with these materials, the heat generated in the drive IC is suppressed from being conducted to the liquid crystal display element substrate.

Finally, the productivity will be described. As described above, it has been shown that productivity can be expected in the fishbone structure because the liquid crystal material hardly needs to be changed at any degree of fineness, but the manufacturing process will be described here.

At present, in the manufacturing process of a liquid crystal display device, most of the manufacturing time is in the process of injecting liquid crystal into the liquid crystal display device. In the liquid crystal injection step, generally, the inside of the liquid crystal display element is set to a vacuum state, and then liquid crystal is injected from a sealing port provided in the liquid crystal display element in advance. Basically, the penetration of liquid crystal is the fastest in the direction along the rubbing direction and the slowest in the direction perpendicular to the rubbing direction. Therefore, as shown in FIG.
9 is preferably arranged on a side substantially perpendicular to the rubbing direction 17.

In the fishbone IPS structure, when the positive type liquid crystal is used, the rubbing direction 17 is substantially parallel to the long axis of the liquid crystal display element, so that the liquid crystal injection port 19 is provided on the short axis side of the liquid crystal display element. Should be placed (Fig. 1
6 (a)).

When the negative type liquid crystal is used, the rubbing direction 17 is substantially parallel to the short axis of the liquid crystal display element. Therefore, if the liquid crystal injection port 19 is arranged on the long side of the liquid crystal display element. Good (Fig. 16 (b)). This can improve the production efficiency.

Embodiments of the present invention will be specifically described below with reference to the drawings. In this embodiment, the image quality such as the aperture ratio, viewing angle, and coloring is evaluated and examined especially for the 141 ppi specification (equivalent to UXGA) in the 14.1 inch liquid crystal display device, but the present invention is not limited to this definition. It can be applied to higher definition.

Example 1 FIG. 1 shows a schematic view of a pixel portion of a liquid crystal display device of this example. Further, FIG. 20 shows an equivalent circuit of the display matrix portion and its peripheral circuits.

The liquid crystal display device is a fishbone IPS having a dogleg-shaped electrode structure, and a voltage is applied between the pixel electrode 102 and the common electrode 103 formed on the same substrate, and the voltage is almost generated on the substrate surface. Liquid crystal molecules are driven by parallel electric fields to control the optical state and display an image.

The liquid crystal display device has a diagonal display of 14.1 inches and a resolution of 141 ppi (equivalent to UXGA). The pixel pitch is 180 micrometers (μm)
Is. The substrate on which the liquid crystal display element is formed has a thickness of 0.7.
A glass substrate whose surface was polished by mm was used.

The signal wiring 1 is provided on one of the glass substrates 108.
01, the scanning wiring 104, and the common wiring 103 were formed in a matrix. First, the scan wiring 104 and the common wiring 103 were formed on a glass substrate, and then an insulating layer (first insulating film 107) was formed using SiN. Further, after forming the signal wiring 101 and the pixel electrode 102 on the insulating layer, an insulating layer (second insulating film 106) was laminated. The common electrode is integrated with the common wiring.

The pixel electrode 102 is connected to the signal wiring 101 via the thin film transistor 105 made of amorphous silicon. Signal wiring 10
1. The scanning wiring 104 is made of chrome, and the pixel electrode 1
02, the common electrode 103 was formed using a transparent conductive film ITO. There is no particular problem with the material of the signal wiring 101 and the scanning wiring 104 as long as it has a low electric resistance, and aluminum, copper or the like may be used. The pixel electrode 102 and the common electrode 103 may be transparent conductive films such as IZO and IGO. Each pixel is a thin film transistor (TFT) 10
5, the pixel electrode 102 and the common electrode 103, and the voltage drives the liquid crystal by the electric field generated between the pixel electrode 102 and the common electrode 103.

Next, the manufacturing process of the liquid crystal display element will be described with reference to FIG. The opposing glass substrate 9 has a structure in which both stripe-shaped RGB color filters 23 and a black matrix 24 are combined. An overcoat resin 22 for flattening was formed on the color filter and the black matrix. An epoxy resin was used as the overcoat resin.

Next, a polyimide alignment film 21 necessary for aligning liquid crystal molecules was formed on the surfaces of both glass substrates.
Generally, a polyimide film is formed by applying polyamic acid, which is its precursor, on a glass substrate with a printing machine or the like and baking it at a high temperature. Next, an alignment treatment for aligning the liquid crystal molecules was performed. The alignment treatment was performed by rubbing the surface of the polyimide alignment film 21 formed on both glass substrates. A rubbing machine was used for the rubbing treatment, and a buff cloth made of rayon was used for the rubbing roll. The rubbing direction was parallel to the long side of the glass substrate.

A sealing material (thermosetting resin) was applied to the peripheral portion of the display area of one of the glass substrates, and the opposing glass substrates were superposed on each other and then heated and pressed to bond and fix both substrates. The gap between the glass substrates (thickness of the liquid crystal layer) was set to 4 micrometers (μm). The injection port for injecting the liquid crystal into the liquid crystal display element was formed on the short side of the glass substrate. Then, liquid crystal was injected from the injection port by a vacuum sealing method, and the injection port was sealed with an ultraviolet curable resin. In this example, a positive type liquid crystal was used.

Polarizing plates 2 are provided on both sides of the combined glass substrate.
5 was attached to complete the liquid crystal display device. The polarizing plates were arranged in a crossed Nicol state and were attached so that the liquid crystal display device had normally closed characteristics (black display at low voltage, white display at high voltage).

Further, as shown in FIG. 20, the scanning line driving circuit 27, the signal wiring driving circuit 28, the power supply circuit and the control circuit 30 are connected to the liquid crystal display element to connect the scanning signal voltage, the signal voltage and the timing signal to the liquid crystal display element. Were supplied and driven by active matrix.

After that, the shield case 32, the diffusing plate 33, the light guide 34, and the reflecting plate 3 shown in FIG.
5, the backlight 36, the lower case 37, and the inverter circuit board 38 are combined to form a liquid crystal display device 39.
Assembled. The display characteristics of the liquid crystal display device assembled in this manner were evaluated. The liquid crystal display element assembled in this example has a high definition of 141 ppi and, at the same time, can achieve a high aperture ratio (-40%) by using the transparent electrode ITO.

Further, in the conventional IPS, the brightness unevenness due to the variation in the electrode spacing, which was feared to occur with the narrowing of the electrodes, was not seen. The image quality such as viewing angle and contrast ratio is almost the same as that of S-IPS, which is said to be the highest peak of still images, and the viewing angle is 170 degrees (contrast ratio 10
As described above, the contrast ratio was 350: 1, and no coloring occurred when the screen was viewed from an oblique direction.

As a result, it was possible to obtain a liquid crystal display device that simultaneously achieves all three items of high definition, high image quality, and high aperture ratio.

Example 2 FIG. 2 shows a schematic view of a pixel portion of the liquid crystal display device of this example. The common electrode in the pixel is located above the layer on which the pixel electrode is formed, and is located on the uppermost layer on the electrode substrate except for the alignment film, and because of that, the black matrix in the signal wiring direction on the color filter side substrate. Is different from the first embodiment in that it is unnecessary.

The size, resolution and pixel pitch of the liquid crystal display element are the same as in Example 1, 14.1 inches and 141 pp.
i (equivalent to UXGA) and a pixel pitch of 180 micrometers (μm). A glass substrate having a thickness of 0.7 mm and having a polished surface was used as a substrate for forming the liquid crystal display element.

The scanning wiring 20 is formed on one glass substrate 208.
4 was formed, and then the insulating layer 207 was formed using SiN. Further, after the signal wiring 201 and the pixel electrode 202 are formed over the insulating layer 207, the insulating layer 206 is stacked. After that, the common electrode 203 was further formed. The common electrode is integrated with the common wiring.

The pixel electrode 202 is connected to the signal wiring 201 via the thin film transistor 205 formed of amorphous silicon. Here, the signal wiring and the scanning wiring were formed of chrome, and the pixel electrode and the common electrode were formed using the transparent conductive film ITO. There is no particular problem with the material of the signal wiring and the scanning wiring as long as they have low electric resistance, and aluminum, copper or the like may be used.

IZO is used for the pixel electrode and the common electrode.
Or a transparent conductive film such as IGO may be used. Each pixel is composed of a thin film transistor (TFT), a pixel electrode, and a common electrode, and a voltage drives the liquid crystal by an electric field generated between the pixel electrode and the common electrode.

In this embodiment, the common electrode and the common wiring are integrated and are formed of the transparent conductive film ITO. However, when the resistance of the wiring material is a problem, for example, the common wiring is made of a metal material. It may be formed in a lower layer different from the common electrode, and the common wiring and the common electrode may be connected through the through hole. The results of the examination of the electrode structure having this through hole will be described in the following Example 3.

On the other hand, the opposing glass substrate has a structure in which both stripe-shaped RGB color filters and a black matrix are combined. The black matrix in the signal wiring direction is not formed. The subsequent liquid crystal display device assembling process is the same as that of the first embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display device of the present embodiment has a high definition of 141 ppi and a high aperture ratio (up to 45%). The main reason for increasing the aperture ratio in this embodiment is that the black matrix is not formed in a part of the counter color filter substrate (in the signal wiring direction), and thus the aperture ratio reduction caused by the conventional substrate misalignment occurs. Because it was able to be suppressed.

Further, as in the first embodiment, the uneven brightness due to the variation in the electrode spacing was not visible. The image quality such as viewing angle and contrast ratio is almost the same as that of S-IPS, which is said to be the highest peak of still images, with a viewing angle of 170 degrees (contrast ratio of 10 or more), a contrast ratio of 350: 1, and an oblique direction. It was not colored when I saw the screen from.

As a result, it was possible to obtain a liquid crystal display device which simultaneously achieves the three items of high definition, high image quality and high aperture ratio.

[Embodiment 3] FIG. 3 is a schematic view of a pixel portion of a liquid crystal display device of this embodiment. In the second embodiment, the common electrode is integrated with the common wiring, and the common wiring is the transparent conductive film IT.
It was formed of O. Although this integration did not cause a problem that the image quality is significantly deteriorated in the second embodiment,
For example, depending on the wiring resistance, the problem of signal delay may occur.

Therefore, in this embodiment, the common electrode 303 and the common wiring 310 are separately formed, and the contact hole 309 is formed.
An electrode structure for connecting them is provided. Here, the transparent conductive material ITO is used for the common electrode 303 and the common wiring 310.
Metal chromium was used for this. The size, resolution, and pixel pitch of the liquid crystal display element manufactured in this example are 14.1 inches, 141 ppi (corresponding to UXGA), and the pixel pitch is 180 micrometers (μm), as in the first example.

First, the scanning wiring 30 is formed on the glass substrate 308.
4 and the common wiring 310 are formed of metallic chromium. After that, the insulating layer 307 was formed using SiN, the signal wiring 301 and the pixel electrode 302 were further formed, and then the insulating layer 306 was stacked. After that, a contact hole 309 for ensuring the connection between the common electrode and the common wiring is formed,
Then, the common electrode 303 was formed of ITO.

The pixel electrode 302 is connected to the signal wiring 301 via the thin film transistor 305 made of amorphous silicon. The voltage drives the liquid crystal by the electric field generated between the pixel electrode and the common electrode. The assembling process of the liquid crystal display element is similar to that of the second embodiment.

The display characteristics of the assembled liquid crystal display device were evaluated. The display characteristics were almost the same as those in Example 2, and a liquid crystal display device capable of simultaneously achieving the three items of high definition, high image quality, and high aperture ratio could be obtained. In such a structure, a metal electrode having low resistance such as chromium or aluminum is easily used as a material for the common wiring, and a problem such as signal delay does not occur.

[Embodiment 4] FIG. 4 shows a schematic view of a pixel portion of a liquid crystal display device of this embodiment. The feature of the electrode structure in the present embodiment is that the common electrode and the common wiring are not integrated and are connected through a contact hole, the common wiring is arranged in the central portion of the pixel in a direction parallel to the scanning wiring,
That is, the V-shaped electrodes are arranged symmetrically with respect to the central portion of the pixel.

The size, resolution and pixel pitch of the liquid crystal display element manufactured in this example are the same as in Example 1.
It is 4.1 inches, 141 ppi (equivalent to UXGA), and has a pixel pitch of 180 micrometers (μm).

First, the scanning wiring 40 is formed on the glass substrate 408.
4 and the common wiring 410 were made of metallic chrome. After that, the insulating film 407 was formed using SiN, the signal wiring 401 and the pixel electrode 402 were further formed, and then the second insulating film 406 was laminated. After that, the contact hole 40 for ensuring the connection between the common electrode 403 and the common wiring 410
9 (through hole) was formed, and then the common electrode 403 was formed of ITO.

The pixel electrode 402 is connected to the signal wiring 401 via the thin film transistor 405 made of amorphous silicon. The voltage drives the liquid crystal by the electric field generated between the pixel electrode 402 and the common electrode 403. The subsequent assembling process of the liquid crystal display element is similar to that of the second embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. Example 2 for the aperture ratio
Moreover, a high aperture ratio substantially equal to that of Example 3 was realized. Further, the image quality, especially the coloring from the oblique visual field, could be greatly suppressed. It is considered that this is because the dog-legged electrode is arranged in the opposite direction at the symmetry point of the pixel center, and as a result, there are four regions having different liquid crystal molecule rotation directions in one pixel.

In addition, the liquid crystal display device of this embodiment has a large productivity margin, especially compared with the liquid crystal display device of the third embodiment. There are two reasons for this, and one is that there is a common electrode region close to a rhombus in the center of the pixel, and since this region is wide, it is easy to form a contact hole.
Another reason is that since the common wiring 310 is arranged in the central portion of the pixel, there is no short circuit with the scanning wiring 304 formed in the same layer (FIG. 3).

In the electrode structure of the third embodiment (FIG. 3), since the common wiring 310 is arranged at the end of the pixel, there is a possibility of short-circuiting with the scanning wiring of the adjacent pixel. Considering productivity, the design is such that the interval between the common wiring and the scanning wiring of the adjacent pixels is widened. This expands the area where light is not transmitted, and as a result, the aperture ratio may be reduced. In the present embodiment, this problem is avoided in advance, and there is no problem of reduction in aperture ratio due to this reason, and a high aperture ratio can be achieved.

[Embodiment 5] A schematic view of a pixel portion of a liquid crystal display device in this embodiment is shown in FIG. In this embodiment, the following 4
It differs from Example 1 in one respect. The size, resolution, and pixel pitch of the liquid crystal display element manufactured in the example are 14.1 inches, 141 ppi (corresponding to UXGA), and the pixel pitch is 180 micrometers (μm) as in the case of the example 1.

The common electrode in the pixel is formed in the uppermost layer. A part of the common electrode in the pixel is spread so as to overlap with the signal wiring. A low capacitance for reducing the capacitive load caused by the overlap. A color filter substrate having an insulating film does not have a black matrix extending in the signal wiring extending direction.

First, the scanning wiring 50 is formed on the glass substrate 508.
4 was made of metallic chromium. After that, the first insulating film 507 was formed using SiN, the signal wiring 501 and the pixel electrode 502 were further formed, and then the second insulating film 506 was laminated.

The pixel electrode 502 is connected to the signal wiring 501 through the thin film transistor 505 made of amorphous silicon. Next, a third insulating film (low-capacity insulating film) 511 was formed, and a common electrode 503 was formed thereon. As can be seen from the cross-sectional view, the common electrode 5
A part of 03 is overlapped with the signal wiring 501 via a two-layer insulating film.

The low-capacitance insulating film 511 is for reducing the capacitance between the common electrode and the signal wiring caused by this superposition. The low-capacity insulating film 511 preferably has a low dielectric constant, and may be an organic material or an inorganic material.
Although the common electrode and the common wiring are integrated in this embodiment, they may be formed of different layers and different electrode materials and connected through a contact hole as in the third and fourth embodiments. The voltage drives the liquid crystal by the electric field generated between the pixel electrode and the common electrode. The subsequent assembling process of the liquid crystal display element is similar to that of the second embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display device assembled in this example has a high definition of 141 ppi and
A high aperture ratio (up to 50%) can also be achieved.

The main reason for the high aperture ratio in this embodiment is that the black matrix is not formed in a part of the counter color filter substrate (in the signal wiring direction), and the aperture caused by the conventional misalignment of the substrates. This is because the rate decrease can be suppressed, and the common electrode is overlapped with the signal wiring, so that a region without an electrode is expanded in the pixel.

Further, as in the case of Example 1, the uneven brightness due to the variation in the electrode spacing was not visible. The image quality such as the viewing angle and the contrast ratio is almost the same as that of S-IPS, which is said to be the highest still image, the viewing angle is 170 degrees (the contrast ratio is 10 or more), the contrast ratio is 350: 1, and the diagonal direction. It was not colored when I saw the screen from.

As a result, it was possible to obtain a liquid crystal display device that simultaneously achieves the three items of high definition, high image quality, and high aperture ratio.

[Embodiment 6] A schematic view of a pixel portion of a liquid crystal display device according to this embodiment is shown in FIG. In this embodiment, the following 4
It differs from Example 1 in one respect. The size, resolution, and pixel pitch of the liquid crystal display element manufactured in this example are the same as in Example 1, 14.1 inches, 141 ppi (UXGA).
Equivalent), and the pixel pitch is 180 micrometers (μm).

The common electrode in the pixel is formed in the uppermost layer. A part of the common electrode in the pixel spreads so as to overlap the scanning wiring. A low capacitance for reducing the capacitive load caused by the overlap. A color filter substrate having an insulating film does not have a black matrix extending in the extending direction of signal lines and scanning lines.

First, the scanning wiring 60 is formed on the glass substrate 608.
4 was made of metallic chromium. After that, a first insulating film 607 was formed using SiN, a signal wiring 601 and a pixel electrode 602 were further formed, and then a second insulating film 606 was laminated.

The pixel electrode 602 is connected to the signal wiring 601 through the thin film transistor 605 formed of amorphous silicon. After that, the low-capacity insulating film 61
1 was formed, and the common electrode 603 was formed thereon. Note that as can be seen from the cross-sectional view, part of the common electrode 603 overlaps with the scan wiring 604 with the insulating film interposed therebetween. The low-capacitance insulating film 611 is for reducing the capacitance between the common electrode and the scanning wiring caused by this superposition. The low-capacity insulating film preferably has a low dielectric constant, and may be either an organic material or an inorganic material.

Although the common electrode and the common wiring are integrated in this embodiment, they may be formed of different layers and different electrode materials and connected through a contact hole as in the third and fourth embodiments. Good. The voltage drives the liquid crystal by the electric field generated between the pixel electrode and the common electrode. The subsequent assembling process of the liquid crystal display element is similar to that of the second embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display element of this embodiment is
While achieving a high definition of 141 ppi, a high aperture ratio (up to 50%) can be achieved. The main reason for increasing the aperture ratio in this embodiment is that the black matrix is not formed on the counter color filter substrate, so that the reduction in aperture ratio caused by the conventional substrate misalignment can be suppressed. Further, as in Example 1, the uneven brightness due to the variation in the electrode spacing was not visible. The image quality such as the viewing angle and the contrast ratio is almost the same as that of S-IPS which is said to be the highest peak of a still image, the viewing angle is 170 degrees (the contrast ratio is 10 or more) and the contrast ratio is 350:
It was 1, and there was no color when the screen was viewed from an oblique direction.

As a result, it was possible to obtain a liquid crystal display device that simultaneously achieves high definition, high image quality, and high aperture ratio.

[Embodiment 7] A schematic view of a pixel portion of a liquid crystal display device according to this embodiment is shown in FIG. In this embodiment, the following 4
It differs from Example 1 in one respect. The size, resolution, and pixel pitch of the liquid crystal display element manufactured in the example are 14.1 inches, 141 ppi (corresponding to UXGA), and the pixel pitch is 180 micrometers (μm) as in the case of the example 1.

The common electrode in the pixel is formed in the uppermost layer. A part of the common electrode in the pixel is spread so as to overlap the signal wiring and the scanning wiring. To reduce the capacitive load caused by the overlapping. In the color filter substrate having the low-capacity insulating film, the black matrix in the extending direction of the signal wiring and the scanning wiring is not provided.

First, the scanning wiring 70 is formed on the glass substrate 708.
4 was made of metallic chromium. After that, a first insulating film 707 was formed using SiN, a signal wiring 701 and a pixel electrode 702 were further formed, and then a second insulating film 706 was laminated. The pixel electrode 702 is provided with a signal wiring 701 through a thin film transistor 705 formed of amorphous silicon.
It is connected to the. After that, a low-capacity insulating film 711 was formed and a common electrode 703 was formed thereon. As can be seen from the cross-sectional view, a part of the common electrode 703 is a part of the scanning wiring 7
04 and the signal wiring 701 via the insulating film.

The low-capacity insulating film 711 is for reducing the capacitance between the common electrode and the scanning wiring caused by this superposition. The low-capacity insulating film preferably has a low dielectric constant, and may be either an organic material or an inorganic material.

Although the common electrode and the common wiring are integrated in this embodiment, they may be formed of different layers and different electrode materials and connected through a contact hole as in the third and fourth embodiments. Good. The voltage drives the liquid crystal by the electric field generated between the pixel electrode and the common electrode. The subsequent assembling process of the liquid crystal display element is the same as that of the second embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display device assembled in this example has a high definition of 141 ppi and
A high aperture ratio (~ 52%) is also achieved. The main reason for the high aperture ratio in this embodiment is that the black matrix is not formed on the counter color filter substrate and that the common electrode is overlapped with the signal line, so that the region without the electrode spreads in the pixel. That is.

Further, as in Example 1, the uneven brightness due to the variation in the electrode interval was not visible. The image quality such as viewing angle and contrast ratio is almost the same as that of S-IPS, which is said to be the highest peak in still images, with a viewing angle of 170 degrees (contrast ratio of 10 or more) and a contrast ratio of 350: 1. It was not colored when I saw the screen.

As a result, it was possible to obtain a liquid crystal display device that simultaneously achieves the three items of high definition, high image quality, and high aperture ratio.

[Embodiment 8] FIG. 8 shows a schematic view of a pixel portion of a liquid crystal display device according to this embodiment. This example is different from Example 1 in that the shapes of the common electrode and the pixel electrode are different. The common electrode and the pixel electrode are Y-shaped. The size, resolution and pixel pitch of the liquid crystal display element manufactured in the example are the same as those in the example 1, 14.1 inches and 14 inches.
The pixel pitch is 1 ppi (equivalent to UXGA) and the pixel pitch is 180 micrometers (μm).

First, the scanning wiring 80 is formed on the glass substrate 808.
4 and the common wiring integrated with the common electrode 803 were formed. After that, a first insulating film 807 was formed using SiN, a signal wiring 801 and a pixel electrode 802 were further formed, and then a second insulating film 806 was laminated.

The pixel electrode 802 is connected to the signal wiring 801 through the thin film transistor 805 made of amorphous silicon. The signal wiring and the scanning wiring were made of chrome metal, and the Y-shaped pixel electrode and the Y-shaped common electrode were formed of ITO transparent electrodes.

In this embodiment, the V-shaped electrode is a Y-shaped electrode to prevent the reverse domain generated in the central portion of the pixel. The voltage drives the liquid crystal by the electric field generated between the pixel electrode and the common electrode.
The subsequent steps of assembling the liquid crystal display element are the same as those in the first embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display device assembled in this example has a high definition of 141 ppi and
A high aperture ratio (~ 40%) can also be achieved. Further, as in Example 1, the uneven brightness due to the variation in the electrode spacing was not visible. The image quality such as viewing angle and contrast ratio is almost the same as that of S-IPS, which is said to be the highest peak in still images, the viewing angle is 170 degrees (contrast ratio 10 or more), the contrast ratio is 350: 1, and the diagonal direction. It was not colored when I saw the screen from.

As a result, it was possible to obtain a liquid crystal display device that simultaneously achieves the three items of high definition, high image quality, and high aperture ratio.

Further, the examination results carried out in Examples 2 to 7 show the same effect in the Y-shaped electrode. Representative electrode structures using Y-shaped electrodes corresponding to each are shown in FIGS. Further, also in the Y-shaped electrode structure, the common electrode and the common wiring may be independently formed and connected through the contact hole.

[Embodiment 9] A schematic view of a pixel portion of a liquid crystal display device in this embodiment is shown in FIG. As can be seen from the figure, in the Y-shaped pixel electrode 2 and the common electrode 3 which are adjacent to each other, the region where the center line overlaps with the insulating film is completely eliminated. The size, resolution and pixel pitch of the liquid crystal display device manufactured in the example are the same as those in the example 1.
Similar to the above, 14.1 inches, 141 ppi (corresponding to UXGA), and a pixel pitch of 180 micrometers (μm). The assembling process of the liquid crystal display device is the same as that of the eighth embodiment except that the center lines of the common electrode and the pixel electrode which are adjacent to each other are not overlapped.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display device assembled in this example has a high definition of 141 ppi and
A high aperture ratio (-40%) can be achieved as in the case of Example 8. In particular, the afterimage was evaluated here.

Image sticking and afterimage of the liquid crystal display device were quantitatively evaluated using an oscilloscope combined with a photodiode.

First, the window pattern is displayed on the screen at the maximum brightness for 30 minutes, and then the halftone display in which the afterimage is most noticeable is switched over the entire display screen so that the brightness becomes 10% of the maximum brightness, and the edge of the window The time until the partial pattern disappeared was evaluated as the afterimage time, and the size ΔB / B (10%) of the brightness variation of the brightness B of the afterimage part of the window and the peripheral halftone part was evaluated as the afterimage intensity. However, the afterimage strength allowed here is 3% or less.

As a result of evaluating the afterimage of the liquid crystal display device of the present example as described above, the afterimage intensity was 1%, and no image sticking or display unevenness due to the afterimage was observed even in the visual image afterimage inspection. High display (image quality) characteristics were obtained.

The electrode structure in which the electrode portions are overlapped (see FIG.
The result of examination of 2 (b)) will be described in Comparative Example 1 below.

[Embodiment 10] A schematic view of a pixel portion of a liquid crystal display device according to this embodiment is shown in FIG. As can be seen from the figure, in addition to the electrode structure in Example 9, a flattening insulating film 120 is applied and formed on the uppermost layer. The size, resolution, and pixel pitch of the liquid crystal display element manufactured in this example are the same as in Example 1, 14.1 inches, 141p.
pi (corresponding to UXGA) and a pixel pitch of 180 micrometers (μm). The assembling process of the liquid crystal display device is the same as that of the eighth embodiment except that the center lines of the common electrode and the pixel electrode which are adjacent to each other are not overlapped.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display element of this embodiment is
While achieving a high definition of 141 ppi, a high aperture ratio (-40%) was achieved as in Example 8. In particular, the afterimage was evaluated here.

The image sticking and afterimage of the liquid crystal display device were quantitatively evaluated by using an oscilloscope combined with a photodiode.

First, the window pattern is displayed on the screen at the maximum brightness for 30 minutes, and then the halftone display in which the afterimage is most noticeable is switched over the entire display screen so that the brightness becomes 10% of the maximum brightness, and the edge of the window is displayed. The time until the partial pattern disappeared was evaluated as the afterimage time, and the size ΔB / B (10%) of the brightness variation of the brightness B of the afterimage part of the window and the peripheral halftone part was evaluated as the afterimage intensity. However, the afterimage strength allowed here is 3% or less.

Afterimages of the liquid crystal display device of this example were evaluated as described above. As a result, the afterimage intensity was 0.5%, and image sticking and display unevenness due to afterimages were not observed even in visual image afterimage inspection. However, a very high display (image quality) characteristic was obtained.

[Embodiment 11] As described above, in the liquid crystal display device having the vertical electrode structure shown in FIGS. 5 and 6, for example, the signal wirings 501 and 601 and the pixel electrodes 502 and 6 are used.
Since 02 is formed in the same layer and close to each other, a problem such as a short circuit may occur. To improve productivity, these electrodes are formed in different layers. As shown in FIG. 14, there are two types of vertical electrode structures for forming the layers in different layers, considering the layers in which pixel electrodes can be arranged.

However, when the afterimage caused by the accumulated charge is considered, it affects the afterimage generation which influences the image quality.
Therefore, in this example, the afterimage was evaluated by the liquid crystal display device having the vertical electrode structure shown in FIGS.
The size, resolution and pixel pitch of the liquid crystal display element manufactured in this example are the same as in Example 1, 14.1 inches,
The pixel pitch is 141 ppi (equivalent to UXGA) and the pixel pitch is 180 micrometers (μm). The assembling process of the liquid crystal display device is similar to that of the fifth embodiment. The liquid crystal display devices for each electrode vertical structure are 14 (a) and 14 (b).

Afterimage characteristics of the liquid crystal display device thus assembled were evaluated. Image sticking of liquid crystal display device,
The afterimage was evaluated using an oscilloscope combined with a photodiode in order to quantitatively evaluate the afterimage.

First, the window pattern is displayed on the screen at the maximum brightness for 30 minutes, and then the halftone display in which the afterimage is most noticeable is switched over the entire display screen so that the brightness becomes 10% of the maximum brightness, and the edge of the window is displayed. The time until the partial pattern disappeared was evaluated as the afterimage time, and the size ΔB / B (10%) of the brightness variation of the brightness B of the afterimage part of the window and the peripheral halftone part was evaluated as the afterimage intensity. However, the afterimage strength allowed here is 3% or less.

Afterimages of the liquid crystal display device of this example were evaluated as described above. As a result, the afterimage intensity was 1.5%.
Although it was small, the time until the afterimage completely disappeared is 1
It was confirmed that (b) was several minutes longer than 4 (a). This is because, considering the CR equivalent circuit model as shown in FIG. 17, the relaxation time constant τ becomes large because there is little dielectric material interposed between the electrodes. From this, it was found that as many dielectrics as possible should intervene in the path of the lines of electric force passing through the pixel electrode-liquid crystal-common electrode.

[Embodiment 12] The structure of the liquid crystal display element of this embodiment is the same as that of the first embodiment. An image cannot be displayed unless a signal is supplied to the signal wiring and scanning wiring of this liquid crystal display element. A drive IC supplies a drive signal for displaying this image.

The common wiring, the signal wiring, and the scanning wiring from each pixel are extended to the peripheral portion of the substrate to form an electrode pattern having a one-to-one correspondence with the electrode pattern of the driving IC.

In the conventional FCA mounting, as shown in FIG. 15A, the drive IC 12 is connected to the electrode pattern 14 formed on the substrate 8 via the Au bumps 13 and the anisotropic conductive film (ACF) 15. .

On the other hand, the structure of this embodiment is shown in FIG. A stress buffer material 1 for relaxing the stress strain generated between the drive IC after thermocompression bonding and the liquid crystal display element substrate at the portion where the drive IC 12 is bonded on the substrate 8 of the liquid crystal display element.
6 was formed. It is appropriate that the cushioning material used here is a heat-resistant material that does not deteriorate due to heat generated by the driving IC.
At the same time, it is desirable that the liquid crystal display element substrate has a heat insulating property that makes it difficult to transfer the heat of the drive IC to the liquid crystal display element substrate and has a heat absorbing effect.

A contact hole is formed in the stress buffer material, and the electrode of the drive IC and the electrode of the liquid crystal display element are connected through the contact hole to supply a necessary signal to the pixel. The process of assembling this liquid crystal display element is similar to that of the first embodiment.

The liquid crystal display device thus obtained was manufactured by FCA.
The problem of stress strain, which is a major issue in mounting, and drive I
Pixels that do not light up due to high-definition and defective connection (point defects, point defects,
The image quality without line defects was also good.

[Embodiment 13] By using a polycrystalline Si-TFT, the driving circuit itself can be incorporated in a pixel. Since the drive circuit can be integrated, a high definition of, for example, 200 ppi is possible.
Further, there are no restrictions on the conventional mounting technology of the drive circuit. In this example, the result of studying a transparent electrode fishbone IPS using a polycrystalline Si-TFT as an active element will be described.

FIG. 21 shows an equivalent circuit of the whole liquid crystal display device in which the peripheral drive circuit and the TFT active matrix are integrated on the same substrate.

A pixel portion 952 and a TFT 951, a vertical scanning circuit 953 for driving the same, a horizontal scanning circuit 954 for dividing a video signal of one scanning line into a plurality of blocks and supplying them in a time division manner, video signal data. Data signal lines Vdr1, Vdg1, Vdb1, ..., A switch matrix circuit 955 for supplying a video signal to the pixel portion for each divided block, a scanning wiring 956, and a signal wiring 957.

FIG. 22 is a sectional view of the TFT active matrix portion in this embodiment. Glass substrate 9 from below
68, buffer layer 969, intrinsic semiconductor layer 900, low resistance n-type semiconductor layer 902, high resistance n-type semiconductor layer 903, gate insulating film 904, through hole portion 905, source electrode 9
58, a signal wire 957, an interlayer insulating film 906, a contact hole 960, a first gate electrode 907, and a second gate electrode 908.

The drive circuit of the liquid crystal display device has a CM
An OS type thin film transistor (TFT) is used.

By combining with such a TFT made of polycrystalline silicon, it was possible to obtain a liquid crystal display device which simultaneously achieves the three items of high definition, high image quality and high aperture ratio.

Comparative Example 1 A schematic view of the pixel portion of the liquid crystal display device of this comparative example is shown in FIG. 12 (b). As can be seen from the figure, the adjacent Y-shaped pixel electrode 2 and common electrode 3 are
This is a structure in which the center line overlaps with an insulating film. In addition, in this structure, the step difference on the surface is large due to the overlap.

The size, resolution and pixel pitch of the liquid crystal display element produced in this comparative example were the same as in Example 1.
It is 4.1 inches, 141 ppi (equivalent to UXGA), and has a pixel pitch of 180 micrometers (μm). The assembling process of the liquid crystal display device is the same as that of the ninth embodiment.

The display characteristics of the liquid crystal display device thus assembled were evaluated. The liquid crystal display device assembled in this comparative example has a high definition of 141 ppi and
A high aperture ratio (~ 40%) was also achieved as in Example 8.
Here, the afterimage was evaluated particularly for comparison with Example 9.

Image sticking and afterimage of the liquid crystal display device were quantitatively evaluated using an oscilloscope combined with a photodiode.

First, the window pattern is displayed on the screen at the maximum brightness for 30 minutes, and then the halftone display in which the afterimage is most noticeable is switched over the entire display screen so that the brightness becomes 10% of the maximum brightness, and the edge of the window is displayed. The time until the partial pattern disappeared was evaluated as the afterimage time, and the size ΔB / B (10%) of the brightness variation of the brightness B of the afterimage part of the window and the peripheral halftone part was evaluated as the afterimage intensity. However, the afterimage strength allowed here is 3% or less.

As a result of evaluating the afterimage of the liquid crystal display device of this comparative example as described above, the afterimage intensity was as large as 5%,
It takes about 30 minutes for the afterimage to disappear, and even in the image afterimage inspection by visual observation, there is clear image sticking,
Display unevenness due to afterimages was confirmed. The occurrence of this bad afterimage is due to the concentration of the electric field due to the overlapping of the pixel electrode and the common electrode and the formation of a large electrode step.

[0243]

According to the present invention, high definition (140 ppi)
As described above, it is possible to provide a liquid crystal display device capable of simultaneously achieving high image quality and high aperture ratio. Further, it is possible to reduce power consumption and improve production efficiency.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an electrode structure of a liquid crystal display device according to a first embodiment.

FIG. 2 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 2.

FIG. 3 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 3.

FIG. 4 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 4.

FIG. 5 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 5.

FIG. 6 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 6.

FIG. 7 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 7.

FIG. 8 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 8.

FIG. 9 is a schematic diagram of a Y-shaped electrode structure for improving a reverse domain in the liquid crystal display device of Example 2.

FIG. 10 is a schematic diagram of a Y-shaped electrode structure for improving a reverse domain in the liquid crystal display device of Example 3.

FIG. 11 is a schematic diagram of a Y-shaped electrode structure for improving the reverse domain in the liquid crystal display device of Example 5.

12 is a schematic diagram illustrating an electrode structure of a liquid crystal display device of Example 9 and Comparative Example 1. FIG.

FIG. 13 is a schematic diagram illustrating an electrode structure of a pixel portion of the liquid crystal display device of Example 10.

FIG. 14 is a schematic cross-sectional view showing an example of arrangement of signal wirings and pixel electrodes of a liquid crystal display device.

FIG. 15 is a schematic cross-sectional view of a liquid crystal display element by the conventional FCA mounting and the mounting of Example 12.

FIG. 16 is an explanatory diagram of a positional relationship between a rubbing direction and a liquid crystal inlet in a liquid crystal display element.

FIG. 17 is a diagram for explaining an equivalent circuit model when the liquid crystal display element is considered as a multilayer dielectric.

FIG. 18 is a schematic explanatory diagram of an electric field direction generated in a pixel in a Y-shaped fishbone structure.

FIG. 19 is an explanatory diagram of arrangement of electrodes of a liquid crystal display element.

FIG. 20 is an explanatory diagram showing an equivalent circuit of the entire liquid crystal display device in which a peripheral drive circuit of the liquid crystal display device and a TFT active matrix are integrated on the same substrate.

FIG. 21 is an explanatory diagram illustrating a configuration of a drive system of a liquid crystal display device.

FIG. 22 is a schematic cross-sectional view of a unit pixel of a TFT active matrix portion of the liquid crystal display device of Example 13.

FIG. 23 is a schematic exploded perspective view illustrating each component of the liquid crystal display device.

[Explanation of symbols]

1, 101, 201, 301, 401, 501, 60
1, 701, 801, 901, 1001, 1101 ... Signal wiring, 2, 102, 202, 302, 402, 50
2,602,702,802,902,1001,11
01 ... Pixel electrode, 3, 103, 203, 303, 40
3,503,603,703,803,903,100
3, 1103 ... Common electrode, 4, 104, 204, 30
4,404,504,604,704,804,90
4, 1004, 1104 ... Scan wiring, 5, 105, 20
5,305,405,505,605,705,80
5,905,1005,1105 ... Thin film transistor (TFT), 6,106,206,306,406,5
06,606,706,806,906,1006,1
106 ... Second insulating film, 7, 107, 207, 307, 4
07, 507, 607, 707, 807, 907, 10
07, 1107 ... First insulating film, 8, 108, 208, 3
08,408,508,608,708,808,90
8, 1008, 1108 ... Substrate, 309, 409, 10
09 ... Contact hole (through hole), 310, 4
10, 1010 ... Common wiring, 611, 711, 111
1, ... Third insulating film (low capacitance insulating film), 12 ... Driving IC,
13 ... Au bump, 14 ... Electrode pattern, 15 ... Anisotropic conductive film (ACF), 16 ... Stress buffering material, 17 ... Rubbing direction, 18 ... Liquid crystal panel, 19 ... Liquid crystal injection port, 20 ... Liquid crystal, 21 ... Alignment Film, 22 ... Overcoat film (color filter protective film), 23 ... Color filter, 24 ... Black matrix, 25 ... Polarizing plate, 26 ... Electric field, 27 ... Scan electrode drive circuit, 28 ... Signal electrode drive circuit, 29 ... Common Electrode drive circuit, 30 ... Power supply circuit and control circuit,
31 ... Liquid crystal display element (liquid crystal display panel), 32 ... Shield case, 33 ... Diffusion plate, 34 ... Light guide plate, 35 ... Reflector plate, 36 ... Backlight, 37 ... Lower case, 38 ... Inverter circuit board, 39 ... Liquid crystal display device, 900 ... Intrinsic semiconductor layer, 902 ... Low resistance n-type semiconductor layer, 903 ... High resistance n-type semiconductor layer, 904 ... Gate insulating film, 905 ... Through hole portion, 906 ... Interlayer insulating film, 907 ... First , 908 ... Second gate electrode, 951 ... Thin film transistor (TFT), 952 ... Pixel portion, 953 ... Vertical scanning circuit, 954 ... Horizontal scanning circuit, 955 ... Switch matrix circuit, 956 ... Scan wiring, 957 ... Signal Wiring, 9
58 ... Source electrode, 960 ... Contact hole, 961
... Pixel electrode, 968 ... Glass substrate, 969 ... Buffer layer, 120 ... Upper planarization insulating film.

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Claims (25)

[Claims] 1. A pair of substrates, at least one of which is transparent,
A liquid crystal layer sandwiched between the pair of substrates, a plurality of scanning wirings on one side of the substrate, a plurality of signal wirings formed in a matrix on the scanning wirings, the plurality of signal wirings and the plurality of signal wirings. A plurality of active elements formed corresponding to respective intersections with the scanning lines, a plurality of pixel electrodes connected to the active elements, and a common line formed between each of the plurality of scanning lines, A plurality of common electrodes connected to the plurality of common wirings, a voltage is applied between the pixel electrode and the common electrode, and a parallel electric field predominantly generated in the pair of substrates is used to align the liquid crystal. In a liquid crystal display device that performs display by controlling, the pixel electrode and the common electrode are both formed in a V shape by a transparent conductive film, and the pixel is surrounded by the scanning wiring and the signal wiring. Image in the longitudinal direction of The V-shaped pixel electrodes and the V-shaped common electrodes are alternately arranged so as to divide an element, and pixel electrodes within the same pixel are at both ends of the pixel, and common electrodes are at the pixel positions. A liquid crystal display device, which is connected at both ends. 2. A pair of substrates, at least one of which is transparent,
A liquid crystal layer sandwiched between the pair of substrates, a plurality of scanning wirings, a plurality of signal wirings formed in a matrix on the scanning wirings, and the plurality of signal wirings on one of the pair of substrates. A plurality of active elements formed corresponding to respective intersections with the plurality of scanning lines, a plurality of pixel electrodes connected to the active elements, and a common formed between the plurality of scanning lines Wiring and a plurality of common electrodes connected to the plurality of common wirings, a voltage is applied between the pixel electrode and the common electrode, and a parallel electric field predominantly generated in the pair of substrates causes the liquid crystal In a liquid crystal display device that controls the orientation to perform display, both the pixel electrode and the common electrode are transparent conductive films.
The Y-shaped pixel electrode and the Y-shaped common electrode are alternately arranged so as to divide the pixel in the longitudinal direction of the pixel formed in the V-shape and surrounded by the scanning wiring and the signal wiring. And a pixel electrode within the same pixel is connected to both ends of the pixel, and a common electrode is connected to both ends of the pixel. 3. The Y-shaped pixel electrode and the Y-shaped common electrode are formed in different layers via an insulating film, and the Y-shaped pixel electrode and the Y-shaped common electrode center line are adjacent to each other. The liquid crystal display device according to claim 2, wherein the liquid crystal display device does not have a region overlapping in a direction perpendicular to the substrate on which the electrode group is formed. 4. The signal line, the scanning line, the common line, the common electrode, and the pixel electrode are formed between a liquid crystal layer and a glass substrate, of which the common electrode is another electrode group and The wiring group is formed in a different layer through at least one insulating film, and the common electrode is formed closest to the liquid crystal layer among the other electrode groups and the wiring group. 2. The liquid crystal display device according to item 2. 5. The liquid crystal display device according to claim 4, wherein a part of the common electrode is formed so as to overlap with the signal wiring via at least one insulating film. 6. A low-capacity insulating film for reducing a capacitive load is interposed between the common electrode and the signal line at least in a region where the common electrode and the signal line overlap each other. Item 5. The liquid crystal display device according to item 5. 7. A light-shielding black matrix extending in the scanning wiring extending direction is formed on a substrate facing a substrate on which the electrode group and the wiring group are formed, and the signal wiring is formed. 7. The liquid crystal display device according to claim 4, 5 or 6, wherein a black matrix for shading is not formed in the extending direction. 8. The liquid crystal display device according to claim 4, wherein a part of the common electrode is formed so as to overlap the scanning wiring with at least one insulating film interposed therebetween. 9. A low-capacity insulating film for reducing a capacitive load is interposed between the common electrode and the scanning wiring at least in a region where the common electrode and the scanning wiring overlap. Item 9. A liquid crystal display device according to item 8. 10. The liquid crystal display device according to claim 4, wherein a part of the common electrode is formed so as to be simultaneously overlapped on both the scanning wiring and the signal wiring through at least one insulating film. . 11. At least a region where the common electrode and the signal line overlap, and a region where the common electrode and the scanning line overlap, between the common electrode and the signal line, and Between the common electrode and the scanning wiring,
The liquid crystal display device according to claim 10, wherein a low-capacity insulating film for reducing the capacitive load is interposed. 12. The liquid crystal display device according to claim 8, wherein a black matrix for light shielding is not formed on a substrate facing a substrate on which the electrode group and the wiring group are formed. 13. The pixel electrode is formed in a layer farthest from a layer in which the common electrode is formed.
3. The liquid crystal display device according to any one of 2. 14. The liquid crystal display according to claim 1, wherein an arrangement structure of the common electrode and the pixel electrode is arranged in a pixel in an inverted state with an intersection of diagonal lines of the pixel as a center of symmetry. apparatus. 15. The common electrode and the common wiring are formed in different layers, at least one insulating film is interposed between these electrodes, and the common electrode and the common wiring are formed through a contact hole formed in the insulating film. 15. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is connected. 16. A flattening process for flattening a step formed in the step of forming the electrode group, directly below an alignment control film for aligning liquid crystals on the substrate side where the electrode group is formed. The liquid crystal display device according to claim 1, further comprising an insulating film. 17. The at least one active element is formed in one pixel surrounded by the scanning wiring and the signal wiring, and the active element is made of polycrystalline silicon. 16. The liquid crystal display device according to any one of 15 to 15. 18. A drive IC for supplying a signal to the scan wiring, the signal wiring, and the common wiring is an FCA.
The liquid crystal display device according to claim 1, which is directly mounted on the substrate that constitutes the liquid crystal display device by mounting. 19. A stress buffer material for relaxing stress strain is arranged between the drive IC and the substrate constituting the liquid crystal display device in contact with the drive IC and the substrate. The liquid crystal display device according to item 1. 20. The coefficient of thermal expansion of the material forming the drive IC and the coefficient of thermal expansion of the substrate are substantially the same.
8. The liquid crystal display device according to item 8. 21. The liquid crystal display device according to claim 18, wherein the drive IC is directly mounted on the substrate by using an ultraviolet curable resin without thermocompression bonding. 22. A heat insulating material or heat absorbing material for preventing heat generated by the driving IC from being conducted to the substrate is provided between the driving IC and the substrate in contact with the driving IC. The liquid crystal display device according to item 1. 23. The liquid crystal display device according to claim 1, wherein the transparent conductive film is made of at least one of indium tin oxide (ITO), indium germanium oxide (IGO) and indium zinc oxide (IZO). . 24. The liquid crystal display device has a resolution of 140 ppi.
The liquid crystal display device according to claim 1, which is the above. 25. At least one of the sides of the substrate constituting the liquid crystal display device, which is substantially orthogonal to the rubbing direction, has at least one sealing port for injecting the liquid crystal, and the sealing is performed after the liquid crystal is injected. The liquid crystal display device according to any one of claims 1 to 24, which is sealed with a sealing material for closing the inlet.