JP2004046267A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably provide a bright liquid crystal display device having a high image quality. <P>SOLUTION: The liquid crystal display device having a plurality of thin film transistors has a pair of substrates and a liquid crystal layer held between the pair of substrates, and at least one of the pair of substrates has an electrode structure formed to generate an electric field dominantly having components parallel with one of the pair of substrates, in the liquid crystal layer, a non-conductive layer formed so as to come into contact with the liquid crystal layer, and a color filter arranged on the non-conductive layer, and a surface coming into contact with the color filter, of the non-conductive layer makes the color filter flat, and a surface coming into contact with the liquid crystal layer controls orientation of liquid crystal of the liquid crystal layer. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a thin film transistor type liquid crystal display device having good mass productivity, low cost, and good viewing angle characteristics.

(4) In a conventional thin film transistor type liquid crystal display device, a transparent electrode formed on the interface between two substrates and opposed to each other is used as an electrode for driving the liquid crystal layer. This is because a display method typified by a twisted nematic display method, which operates by setting the direction of an electric field applied to the liquid crystal to a direction substantially perpendicular to the substrate interface, is employed. On the other hand, as a method in which the direction of the electric field applied to the liquid crystal is made substantially parallel to the substrate interface, a method using a pair of comb-teeth electrodes has been proposed, for example, in Patent Document 1 below. In this case, the electrode does not need to be transparent, and an opaque metal electrode having high conductivity can be used.

JP-B-63-21907

(4) In the above-mentioned conventional technology, it is necessary to use a vacuum-based manufacturing equipment such as a sputtering apparatus in order to form a transparent electrode typified by ITO, and the equipment cost is enormous. In addition, the use of a vacuum-based manufacturing facility involves an operation of removing contamination in a vacuum furnace, which requires a great deal of time, which significantly increases the manufacturing cost. In general, a transparent electrode has irregularities of about several tens of nm on its surface, which makes it difficult to process a fine active element such as a thin film transistor. Further, the convex portion of the transparent electrode often separates and mixes with other portions such as the electrode, causing a dot-like or linear display defect, and significantly reducing the yield. For these reasons, it has not been possible to stably provide a low-cost liquid crystal display device that meets market needs. Further, in the above-described conventional technology, there are many problems in terms of image quality. In particular, the luminance change when the viewing angle direction is changed is remarkable, and when halftone display is performed, there is a practical problem such that the grayscale level is inverted in each strong direction. Further, the uneven structure of the thin-film transistor element causes a poorly-aligned domain around the thin-film transistor element, and a light-shielding film having a large area is required for the countermeasure, and the light use efficiency is remarkably reduced.

On the other hand, if the comb-shaped electrode disclosed in Patent Document 1 is used, it is not necessary to use a transparent electrode, and there is a possibility that the above problem can be solved. However, it has not been put to practical use for the following reasons. That is, in this known technique, since the interdigitated comb-teeth electrode pair is used, the pattern in the pixel becomes fine and complicated, and the mass productivity is extremely low. In particular, in a display having a large amount of display information and a small pixel size, it is almost impossible to put an electrode having a comb-teeth structure in one pixel, and even if it is inserted, the aperture ratio is extremely low and almost all light is effectively used. Only dark displays that can not be realized. In principle, the aperture ratio can be increased to a practical level if the electrode width of the comb electrode is reduced to about 1 to 2 μm, but in practice such fine wires are formed uniformly and without breakage over the entire large substrate. It is extremely difficult to do. That is, in the above-described conventional technology, since the interdigitating comb-shaped electrodes are used, the pixel aperture ratio and the manufacturing yield are in a trade-off relationship, and it is difficult to provide a liquid crystal display device having a bright image at low cost. Met.

The present invention solves these problems at the same time. The purpose of the present invention is, firstly, a low-cost thin film transistor type liquid crystal which can be mass-produced with a high yield without using a transparent electrode, with high-contrast equipment and low-cost equipment. It is to provide a display device. Second, it is an object of the present invention to provide a thin film transistor type liquid crystal display device which can be driven at a low voltage, has good viewing angle characteristics, and can easily perform multi-tone display. Third, the degree of freedom in selecting usable liquid crystal compositions and alignment film materials is increased, thereby increasing the latitude of processes such as liquid crystal panel fabrication, achieving a high aperture ratio and suppressing pixel deterioration, and achieving light transmission. It is an object of the present invention to provide a brighter thin film transistor type liquid crystal display device with an increased rate. Fourth, in addition to the first to third objects, it is an object of the present invention to provide a thin film transistor type liquid crystal display device having a simpler structure and a high production yield.

In a liquid crystal display device having a plurality of thin film transistors, a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and a component formed on one of the pair of substrates and being predominantly parallel to the substrates. An electrode structure for generating an electric field having an electric field in the liquid crystal layer, a non-conductive layer in contact with the liquid crystal layer, and a color filter disposed on the non-conductive layer, and the color of the non-conductive layer The surface in contact with the filter flattens the color filter, and the surface in contact with the liquid crystal layer has a structure for controlling the orientation of the liquid crystal in the liquid crystal layer.

カ ラ ー The color filter may be formed on the other of the pair of substrates.

The non-conductive layer desirably has at least one organic polymer layer, and the organic polymer layer desirably contains an epoxy resin or a polyimide resin.

It is desirable that the non-conductive layer has at least one inorganic layer.

形成 By forming in this manner, the organic polymer for flattening the unevenness of the color filter can also be used as the alignment film for controlling the alignment of the liquid crystal molecules, which is effective in reducing the cost.

In a liquid crystal display device having a plurality of thin film transistors, a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and An electrode structure for generating an electric field having a parallel component in the liquid crystal layer; and an insulating film formed on the electrode structure and the plurality of thin film transistors; and one surface of the insulating film in contact with the liquid crystal layer. Is configured to control the alignment of liquid crystal molecules in the liquid crystal layer.

他方 It is desirable that the other surface of the insulating film in contact with the thin film transistors be flattened.

絶 縁 The insulating film desirably has at least one organic polymer layer, and the organic polymer desirably includes an epoxy resin or a polyimide resin.

It is desirable that the insulating film has at least one inorganic layer.

ラ Thus, by performing the rubbing treatment on the organic insulating layer covering the thin film transistor element, the organic insulating layer can have both functions of a protective film of the thin film transistor element and a liquid crystal molecule alignment control film.

In addition, when an organic polymer is used as an insulating film and the surface is subjected to a surface alignment treatment such as direct rubbing or the like, an electric field is applied in parallel to a substrate interface. In this method, liquid crystal molecules having a low tilt angle may be used. Since the uniformity is achieved and the display unevenness is suppressed lower than in the conventional method, the degree of freedom in selecting the alignment film material is increased.

Furthermore, the tolerance for the variation on the interface with the alignment film described above is increased, and defects due to the interface are almost eliminated, so that steps such as inspection and aging can be greatly simplified, and manufacturing costs can be reduced.

Further, according to the present invention, an inorganic insulating film conventionally formed by a vacuum system such as a CVD (Chemical Vapor Deposition) method can be replaced with an organic insulating layer which can be manufactured at a lower cost, which is effective for cost reduction. .

According to the present invention, first, it is possible to provide a low-cost thin film transistor type liquid crystal display device which can be mass-produced with a high yield at a high yield with low cost equipment without a transparent electrode. It is possible to provide a thin film transistor type liquid crystal display device having good characteristics and easy multi-gradation display. Thirdly, the process and material for liquid crystal alignment have a large margin, so that the aperture ratio can be increased and the light transmittance can be increased. Fourth, it is possible to provide a brighter thin film transistor type liquid crystal display device, and fourthly, to provide a thin film transistor structure having a simpler structure in addition to the first to third effects, to increase the aperture ratio, A brighter thin film transistor type liquid crystal display device having an increased light transmittance can be provided.

First, the angle φ _P formed by the polarization transmission axis of the polarizing plate with respect to the direction of the electric field, the angle φ _LC formed by the direction of the long axis (optical axis) of the liquid crystal molecules near the interface, and the phase difference plate inserted between the pair of polarizing plates The definition of the angle φ _R formed by the fast axis is shown in FIG. 6 (FIG. 6). Phi _P1 optionally Since the polarizer and the liquid crystal interface is a pair up and down, respectively, φ _P2, φ _LC1, referred to as phi _LC2. FIG. 6 corresponds to a front view of FIG. 1 described later.

Next, the operation of the present invention will be described with reference to FIG.

1A and 1B are side sectional views showing the operation of the liquid crystal in the liquid crystal panel of the present invention, and FIGS. 1C and 1D are front views thereof. In FIG. 1, the thin film transistor element is omitted. Further, in the present invention, a plurality of pixels are formed by forming a stripe-shaped electrode. Here, one pixel portion is shown. FIG. 1A shows a cross section of the cell side when no voltage is applied, and FIG. 1C shows a front view at that time. Linear electrodes 1 and 2 are formed inside a pair of transparent substrates, and an alignment control film 4 is applied and aligned thereon. A liquid crystal composition is sandwiched between the two. The rod-shaped liquid crystal molecules 5 have a slight angle with respect to the longitudinal direction of the electrodes 1 and 2 when no electric field is applied, that is, 45 degrees ≦ | φ _LC | <
90 degrees. Here, the orientation of liquid crystal molecules on the upper and lower interfaces is parallel, that is, φ _LC1 = φ _LC2 . The dielectric anisotropy of the liquid crystal composition is assumed to be positive. Next, when an electric field 7 is applied, the liquid crystal molecules change their directions in the direction of the electric field as shown in FIGS. 1 (b) and 1 (d). By disposing the polarizing plate 6 in the polarizing axis direction 9 of the polarizing plate, the light transmittance can be changed by applying an electric field. As described above, according to the present invention, it is possible to provide a display that provides a contrast without a transparent electrode. In FIG. 1B, the angle between the substrate surface and the direction of the electric field is large and appears to be non-parallel. However, this is a result of enlarging the thickness direction and is actually 20 degrees or less. Hereinafter, in the present invention, those having an angle of 20 degrees or less are collectively referred to as a lateral electric field. In FIG. 1, the electrodes 1 and 2 are formed separately on the upper and lower substrates. However, the effect is not changed even if the electrodes 1 and 2 are provided on one of the substrates. Rather, in consideration of the case where the pattern of wiring or the like becomes finer or various deformations due to heat, external force, and the like, it is desirable to provide the one substrate with higher precision because alignment can be performed with higher accuracy. In addition, the dielectric anisotropy of the liquid crystal composition is assumed to be positive, but may be negative. In this case, the initial alignment state is set so as to have a slight angle | φ _LC | (that is, 0 degree <| φ _LC | ≦ 45 degrees) from a direction perpendicular to the longitudinal direction of the electrodes 1 and 2 (electric field direction 7). Orient.

Hereinafter, the operation of each of the three objects of the present invention will be described.

(1) High contrast without a transparent electrode As a specific configuration for imparting contrast, a mode using a state in which liquid crystal molecule orientations on upper and lower substrates are substantially parallel (using an interference color due to birefringence phase difference). Therefore, a mode utilizing the state in which the liquid crystal molecules on the upper and lower substrates intersect and the molecular arrangement in the cell is twisted (the polarization plane rotates in the liquid crystal composition layer) is referred to as a birefringence mode. Since optical rotation is used, it is referred to as an optical rotation mode here). In the birefringence mode, the voltage changes the azimuth of the molecular axis (optical axis) in a plane while the direction of the molecular axis (optical axis) is substantially parallel to the substrate interface, and changes the angle formed by the axis of the polarizing plate set at a predetermined angle. Change the transmittance. In the optical rotation mode, similarly, only the orientation in the molecular major axis direction is changed by applying a voltage, but in this case, the change in optical rotation due to unwinding of the helical line is used.

(4) Next, the quantitative structure and operation for increasing the contrast ratio by making the display achromatic will be described below in two cases, that is, the case where the birefringent mode is used and the case where the optical rotation mode is used.

I. Display in Birefringence Mode Generally, the light transmittance T / To when a uniaxial birefringent medium is inserted between two polarizing plates arranged orthogonally is expressed by the following equation. Here, χeff is the effective optical axis direction (the angle between the optical axis and the polarization transmission axis) of the liquid crystal composition layer, deff is the effective thickness of the birefringent liquid crystal composition layer, and Δn is the refractive index Anisotropy and λ represent the wavelength of light. Here, the purpose of making the optical axis direction of the liquid crystal composition layer an effective value is that liquid crystal molecules are fixed on the interface in an actual cell, and all liquid crystal molecules are parallel to each other in the cell when an electric field is applied. In view of the fact that the orientation is not uniform and large deformation occurs particularly in the vicinity of the interface, the average value thereof is to be treated as an apparent value when a uniform state is assumed.

T / To = sin ² (2χeff) · sin ² (πdeff · Δn / λ) (1)
In order to obtain a normally closed characteristic in which a dark state is applied when a low voltage _{VL is} applied and a bright state is applied when a high voltage _{VH is} applied, the polarizing plate is arranged such that the transmission axis (or absorption axis) of one of the polarizing plates is aligned with the liquid crystal molecule alignment direction ( Rubbing axis), that is, φ _P1 ≒ φ _LC1 = φ _LC2, and the transmission axis of the other polarizing plate is perpendicular to it, ie, φ _P2 = φ _P1 +90 degrees. When no electric field is applied, χeff in equation (1) is 0, so that the light transmittance T / To is also 0. On the other hand, when an electric field is applied, the value of χeff increases according to the intensity, and reaches a maximum at 45 degrees. At this time, assuming that the wavelength of the light is 0.555 μm, the effective deff · Δn may be set to 0.28 μm, which is a half wavelength, in order to achieve achromatic color and maximize the transmittance. Actually, since there is a margin, it is sufficient that the distance is between 0.21 and 0.36 μm, but it is desirable to set a value between 0.24 and 0.33 μm.

On the other hand, in order to obtain a normally open characteristic in which a bright state is obtained when a low voltage V _{L is} applied and a dark state is obtained when a high voltage V _{H is} applied, Δeff in the equation (1) becomes approximately 45 degrees when no electric field is applied or when a low electric field is applied. What is necessary is just to set the arrangement of the polarizing plates. When an electric field is applied, the value of χeff decreases according to the strength, contrary to the case of normally closed. However, even when χeff becomes minimum (ie, 0), considerable light leaks as it is because of the residual phase difference of the liquid crystal molecules fixed near the interface. According to experiments conducted by the present inventors in which d · Δn was set between 0.27 and 0.37 μm and an effective voltage of 3 to 10 V was applied, the value of the interface residual phase difference was about 0.02 to 0.06 μm. Met. Therefore, by inserting a retardation plate having a birefringence retardation of about 0.02 to 0.06 μm (this retardation is represented as Rf) so as to compensate for the interface residual retardation, the dark state sinks, A high contrast ratio is obtained. The angle φ _R of the fast axis of the retardation plate is made parallel to the effective optical axis χeff of the liquid crystal composition layer when a voltage is applied. In order to completely reduce the brightness of the dark state, it is necessary to exactly match the residual phase difference when a voltage for displaying the dark state is applied. As described above, to satisfy both the sunkenness in the dark state and the transmittance and whiteness in the light state, the following relationship may be satisfied.

0.21 μm <(d · Δn−Rf) <0.36 μm (2)
Preferably,
0.23 μm <(d · Δn−Rf) <0.33 μm (3)

II. In the case of displaying in the optical rotation mode In the conventional twisted nematic (TN) method, as is generally known, when d · Δn is set near 0.50 μm, which is the first minimum condition, a high transmittance, It becomes achromatic. Taking the margin into account, the TN method uses 0.40 to 0.60.
It is good to set it between μm. The polarizing plate is arranged such that the transmission axis (or absorption axis) of one of the polarizing plates is substantially parallel to the liquid crystal molecule alignment direction (rubbing axis) on the interface, that is, φ _LC1 ≒ φ _LC2 . In order to realize a normally closed type, the transmission axis of the other polarizing plate may be set to be parallel to it, and to be a normally open type, it may be set to be perpendicular.

In order to completely eliminate the optical rotation, it is necessary to make the liquid crystal alignment directions near the interface between the upper and lower substrates almost parallel. I have to rotate it almost a degree. When displaying in the birefringence mode, the liquid crystal molecule rotation angle may be about 45 degrees, and the threshold voltage is lower in the birefringence mode.

(2) Improvement of Viewing Angle Characteristics In the display mode of the present invention, the major axis of the liquid crystal molecules is always almost parallel to the substrate, and does not rise, so that the change in brightness when the viewing angle direction is changed is small. In this display mode, a dark state is not obtained by making the birefringence phase difference substantially zero by applying a voltage as in the prior art, and the angle between the long axis of the liquid crystal molecules and the axis (absorption or transmission axis) of the polarizing plate is formed. It's something that changes and is fundamentally different. In the case where the long axis of the liquid crystal molecules rises perpendicularly to the substrate interface as in a conventional TN type, the viewing angle direction in which the birefringence phase difference becomes 0 is only the front direction, that is, the direction perpendicular to the substrate interface. A birefringent phase difference appears, and in a normally open type, light leaks, causing a decrease in contrast and inversion of a gradation level.

(3) Improvement of freedom of selection of alignment film material and liquid crystal material and expansion of process latitude. Further, since liquid crystal molecules do not rise, a large inclination angle (a long axis of liquid crystal molecules and interface Is not required. In the conventional method, if the inclination angle is insufficient, two states having different inclination directions and a domain at a boundary between the two states are generated, which may result in display failure. In this method, instead of giving an inclination angle, the long axis direction of the liquid crystal molecules (rubbing direction) on the substrate interface may be set to a predetermined direction shifted from 0 or 90 degrees with respect to the direction of the electric field. For example, when the dielectric anisotropy of the liquid crystal composition is negative, the angle φ _LC (defined as φ _LC > 0 degree) between the direction of the electric field and the direction of the long axis of the liquid crystal molecules on the substrate interface is 0 degree or more ( (Substantially 0.5 degrees or more), and preferably 2 degrees or more. If the angle is completely 0 degrees, two kinds of deformations in different directions occur, and two different states and domains at their boundaries occur, which may result in display failure. If it is 0.5 degrees or more, the apparent liquid crystal molecule major axis direction (defined as φ _LC (V)) uniformly increases due to the application of the electric field and the increase in the intensity, and the tilt in the opposite direction, ie, φ _LC (V) <0 degrees is never reached. As described above, in the present method, even when the angle (inclination angle) between the interface and the liquid crystal molecule is small, the operation is performed without generating a domain, and therefore, it is possible to set a lower inclination angle. The uniformity of the liquid crystal molecule alignment is better as the lower the inclination angle, the higher the process margin such as rubbing. Therefore, if a low tilt angle is combined with the present method in which an electric field is applied in parallel to the interface, the liquid crystal molecule alignment becomes more uniform, and the display unevenness can be suppressed to be lower than in the conventional method even if there is a similar manufacturing process variation. . In general, the types of alignment films that provide a high tilt angle are fewer than those that provide a low tilt angle, and the use of this method increases the degree of freedom in selecting alignment film materials. For example, even if an organic polymer is used for the flattening film on the color filter and the protective film on the thin film transistor, and it is directly subjected to a surface alignment treatment such as rubbing, an inclination angle is unnecessary, so that it can be shared with the alignment film more easily. Further, it is possible to simplify the process and reduce the cost associated therewith. In order to suppress display unevenness due to manufacturing process variation, the tilt angle may be set to 4 degrees or less, preferably 2 degrees or less.

In addition, the degree of freedom in selecting a liquid crystal material is increased for the following reasons. That is, in the present invention, the pixel electrode and the common electrode have a structure in which an electric field is applied to the liquid crystal composition layer mainly in parallel to the substrate interface, and the distance between the electrodes is the conventional vertical electric field type active matrix type liquid crystal. The distance can be larger than the distance between the opposed transparent electrodes in the display device. Also, the equivalent electrode cross-sectional area can be kept smaller than the conventional one. Therefore, the electric resistance between the paired pixel electrodes according to the present invention can be increased by an order of magnitude between the opposed transparent electrodes in the conventional active matrix type liquid crystal display device. Furthermore, the capacitance between the pixel electrode and the common electrode according to the present invention is connected in parallel with the capacitance element, and a capacitance element with sufficiently high electric resistance can be realized. Accordingly, it is easy to hold the charge accumulated in the pixel electrode, and sufficient holding characteristics can be obtained even if the area of the capacitor which has conventionally sacrificed the aperture ratio is reduced. In addition, although a liquid crystal composition having a very high specific resistance of, for example, 10 ¹² Ωcm is conventionally required, a liquid crystal composition having a lower specific resistance does not pose a problem. This not only increases the degree of freedom in selecting the liquid crystal material, but also increases the process latitude. That is, even if the liquid crystal is contaminated during the process, the image quality is not likely to be poor. In particular, the tolerance for the variation on the interface with the alignment film is increased, and the failure caused by the interface is almost eliminated. Accordingly, steps such as inspection and aging can be greatly simplified, which greatly contributes to the cost reduction of the thin film transistor type liquid crystal display device. Further, the pixel electrode according to the present invention has a simpler shape than the comb-teeth-shaped electrode pair, so that the light use efficiency is improved. There is no need to sacrifice the opening to obtain a capacitor capable of storing a sufficient amount of charges as in the conventional method. Furthermore, if the insulating film that protects the thin film transistor is made of an organic material, the dielectric constant can be made lower than that of an inorganic material. Therefore, the electric field component generated in the vicinity of the pixel electrode in the direction perpendicular to the substrate interface is suppressed to be smaller than the horizontal electric field component. And the liquid crystal operates in a wider area. This also contributes to brightness improvement. Further, when the common electrode is shared with the common electrode of an adjacent pixel, the same operation as the common electrode in the conventional active matrix type liquid crystal display device can be performed, and the structure can be further simplified. It is possible to increase the aperture ratio.

(4) Realization of a simple and high-aperture-ratio thin-film transistor structure and improvement of brightness by using a comb-shaped electrode disclosed in a known example (JP-B-63-21907) for a structure in a pixel including a thin-film transistor In such a case, there is a problem that the aperture ratio is remarkably reduced, whereby the brightness is reduced. In consideration of mass productivity, the width of one comb tooth electrode is required to be about 8 μm, and at least 4 μm or more. For example, there are a total of 17 comb teeth as shown in FIG. 7 shown in JP-B-63-21907. With the same structure, diagonal 9.4 inch color VGA class 0.3 × 0.1
It is impossible to construct a pixel of mm ² .

(4) The present invention has been made by devising means for maintaining the aperture ratio sufficiently while maintaining the advantages of (1) and (2). Instead of a structure in which the aperture ratio has to be reduced like a comb tooth, a practically high aperture ratio can be realized by a simpler electrode structure.

The present invention has a structure in which a common electrode is formed on a counter substrate or a pixel electrode is formed on the same layer. In the above-mentioned known example (Japanese Patent Publication No. 63-21907), in order to form a comb-tooth electrode, the drawing directions of the signal wiring and the common electrode are made orthogonal. That is, the signal wiring is extended in the first direction (Y direction), and the common electrode is extended in the direction perpendicular to it (X direction). On the other hand, a complicated structure such as a comb tooth is avoided by extending all of the signal wiring, the pixel electrode, and the common electrode in the first direction as in the present invention. To reduce the threshold voltage of the liquid crystal and shorten the response time, the distance between the pixel electrode and the common electrode may be reduced, but it is not necessary to use a complicated structure such as a comb.

The present invention will be specifically described with reference to examples.

[Example 1]
As the substrates, two transparent glass substrates having a thickness of 1.1 mm and a polished surface are used. A nematic liquid crystal composition having a positive dielectric anisotropy Δε of 4.5 and a refractive index anisotropy Δn of 0.072 (589 nm, 20 ° C.) is sandwiched between these substrates. The polyimide-based orientation control film applied to the substrate surface is rubbed to have a pretilt angle of 3.5 degrees. The rubbing directions on the upper and lower interfaces are almost parallel to each other, and the angle between the rubbing directions and the direction of the applied electric field is 85 degrees (φ _LC1 = φ _LC2 =
85 °). The gap d was 4.5 μm in a state in which liquid crystal was sealed while spherical polymer beads were dispersed and sandwiched between substrates. Therefore, Δn · d is 0.324 μm. The panel is sandwiched between two polarizing plates (G1220DU manufactured by Nitto Denko Corporation), and the polarization transmission axis of one of the polarizing plates is substantially parallel to the rubbing direction, that is, φ _P1 = 85 °, and the other is perpendicular to it, ie, φ _P2 = −5 °. As a result, normally closed characteristics were obtained.

As shown in FIG. 2A (front view) and FIG. 2B (side sectional view), the structure of the thin film transistor and various electrodes is such that the thin film transistor element (shaded portion in FIG. 2) is a pixel electrode (source electrode) 1 and a signal. The pixel electrode 1 has an electrode (drain electrode) 12 and a scanning electrode (gate electrode) 10, and the pixel electrode 1 extends in a first direction (in FIG. 2, means a vertical direction in the drawing). The common electrode 2 extends in a first direction across a plurality of pixels (in FIG. 2, pixels arranged in a vertical direction in the paper plane), and a thin film transistor element is arranged between the common electrodes.

信号 A signal waveform having information is applied to the signal electrode 12, and a scanning waveform is applied to the scanning electrode 10 in synchronization with the signal waveform. A thin film transistor including a channel layer made of amorphous silicon (a-Si) 16 and a protective insulating film 15 made of silicon nitride (SiN) is arranged between adjacent common electrodes. An information signal is transmitted from the signal electrode 12 to the pixel electrode 1 via the thin film transistor, and a voltage is applied between the common electrode 2 and the liquid crystal portion. In the present embodiment, the common electrode is arranged on the counter substrate side, and the thickness direction is enlarged in FIG. 2B, so that the electric field direction 7 appears to be inclined, but the width is actually reduced to 48 μm. On the other hand, the thickness of the liquid crystal layer is about 6 μm, there is almost no inclination, and the direction of the applied electric field is almost parallel to the substrate surface.

2) As shown in FIG. 2A, the additional capacitance element 11 was formed such that the pixel electrode 1 had a structure in which the gate insulating film 13 was interposed on the scanning wiring 10 on which the projection was formed. The capacitance of the additional capacitance element 11 became about 21 fF. A scanning wiring driving LSI and a signal wiring driving LSI were connected to each scanning wiring 10 and each signal electrode driving circuit 21, respectively.

The electric charge accumulated in the pixel electrode 1 is accumulated in the capacitance between the pixel electrode 1 and the common electrode 2 and about 24 fF which is a capacitance in which the additional capacitance element 11 is connected in parallel. Even if the specific resistance is 5 × 10 ¹⁰ Ωcm, the voltage fluctuation of the pixel electrode 1 can be suppressed. For this reason, it was possible to prevent image quality deterioration.

数 The number of pixels is 40 (× 3) × 30, and the pixel pitch is 80 μm in the horizontal direction (that is, between the common electrodes) and 240 μm in the vertical direction (that is, between the scanning electrodes). The width of the scanning electrode was 12 μm, the gap between adjacent scanning electrodes was 68 μm, and a high aperture ratio of 50% was secured. A stripe-shaped color filter of R, G, and B colors was provided on a substrate facing the substrate having the thin film transistors. A transparent resin for flattening the surface was laminated on the color filter. Epoxy resin was used as the material of the transparent resin. Further, a polyimide-based orientation control film was applied on the transparent resin. A drive circuit is connected to the panel. FIG. 8 shows the configuration of the drive circuit system of this embodiment. The signal electrode 23 and the common electrode 2 extend to the end of the display unit. 9 and 10 show the configuration of the optical system. FIG. 9 shows a transmission type, and FIG. 10 shows a reflection type.

で は Since the present embodiment does not require a transparent electrode, the manufacturing process can be simplified, the yield can be improved, and the cost can be significantly reduced. In particular, extremely expensive equipment having a vacuum furnace for forming the transparent electrode is not required, so that the investment in manufacturing equipment can be significantly reduced and the cost can be reduced. FIG. 3A shows electro-optical characteristics showing the relationship between the effective value of the voltage applied to the pixel and the brightness in this embodiment. The contrast ratio becomes 150 or more at the time of 7V driving, and the difference in the curve when the viewing angle is changed left and right and up and down is extremely small as compared with the conventional method (shown in Comparative Example 1), and the display characteristics change substantially even when the viewing angle is changed. Did not. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated. The aperture ratio was sufficiently high at 50% by simplification of the thin film transistor and electrode structure, and a bright display was realized. The average transmittance of the entire panel was 8.4%. Here, the brightness was defined as a luminance transmittance when two polarizing plates were arranged in parallel.

[Example 2]
In this embodiment, the common electrode arranged on the counter substrate side in the first embodiment is arranged on the same substrate side as the substrate on which the scanning electrodes are arranged. Other configurations are the same as those of the first embodiment. FIG. 4 shows a cross-sectional structure of the thin film transistor and the electrode. The pixel electrode 1, the signal electrode 12, and the scanning electrode 10 are all made of aluminum, and are formed by simultaneous film formation and etching. No conductive substance exists on the counter substrate. Therefore, in the configuration of the present embodiment, even if conductive foreign matter is mixed during the manufacturing process, there is no possibility of touch between the upper and lower electrodes, and the defect rate of touch between the upper and lower electrodes is suppressed to zero. The material for the electrode is not particularly limited as long as it is a metallic material having low electric resistance, and may be chromium, copper, or the like.

Generally, the alignment accuracy of a photomask is significantly higher than the alignment accuracy of a combination between two opposing glass substrates. Therefore, when all of the four types of electrode groups are formed on one substrate as in the present embodiment, alignment at the time of forming each electrode is performed only by the photomask, so that the misalignment between the electrodes is small. Be suppressed. Therefore, the present embodiment is effective for forming a higher definition pattern as compared with the case where the scanning electrodes are formed on the counter substrate.

(4) A bright display having a wide viewing angle characteristic was obtained in the same manner as in Example 1.

[Example 3]
The configuration of this embodiment is the same as that of the first embodiment except for the following requirements.

As shown in FIG. 5, the structure of the thin film transistor and various electrodes was such that a signal electrode 12 was disposed between a pair of pixel electrodes 1 and a common electrode 2 was disposed outside these electrodes. A signal waveform having information is applied to the signal electrode 12, and a scanning waveform is applied to the scanning electrode 10 in synchronization with the signal waveform. The thin film transistor including the amorphous silicon (a-Si) 16 and the silicon nitride (SiN) protective insulating film 15 is disposed at substantially the center of a pair of common electrodes. The same information signal is transmitted from the signal electrode 12 to the two first electrodes 1 via the two thin film transistors, and the same voltage signal is applied to the liquid crystal portion between the common electrodes on both sides having the same potential. By doing so, the electrode spacing can be reduced to about half without complicating the structure of the thin film transistor and the electrode, and a higher electric field can be applied at the same voltage, thereby reducing the driving voltage and achieving a high-speed response. Is done.

広 い The wide viewing angle characteristics and brightness of the first embodiment are also realized in this embodiment.

[Example 4]
The configuration of this embodiment is the same as that of the first embodiment except for the following requirements.

(2) A flattening film 14 (FIG. 2B) made of a transparent polymer was laminated as an organic insulating layer on the color filter, and the surface was directly rubbed without forming another film as an orientation control film thereon. Epoxy resin was used as the material of the transparent polymer. This epoxy resin has both functions of flattening and controlling the alignment of liquid crystal molecules. The liquid crystal composition layer was in direct contact with the epoxy resin, and the tilt angle at the interface was 0.5 degrees. Thereby, the step of applying the alignment film was eliminated, and the production was easier and shorter. Generally, in the conventional TN type, the characteristics required for the orientation control film are diversified, and it is necessary to satisfy all of them. Therefore, the materials are limited to some materials such as polyimide. A particularly important characteristic is the tilt angle. However, as described above, the present invention does not require a large tilt angle, and therefore, the material selection range is significantly improved.

(4) When the electro-optical characteristics in the present example were measured, the difference between the curves when the viewing angle was changed left and right and up and down was very small, and the result was that the display characteristics hardly changed, as in Example 1. In addition, although the tilt angle was as small as 0.5 degree, the liquid crystal alignment was good, and no alignment defect domain was generated.

[Example 5]
The transparent polymer for flattening in Example 4 was changed from an epoxy resin to a polyimide resin. Similarly, the surface of the polyimide resin was directly rubbed to have both functions of flattening and controlling the alignment of liquid crystal molecules. The tilt angle at the interface was 2 degrees. As a result, the display characteristics were hardly changed as compared with the other examples. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Example 6]
The configuration of this embodiment is the same as that of the first embodiment except for the following requirements.

The protective insulating film 15 (FIG. 2 (b)) for protecting the thin film transistor is changed from silicon nitride to an organic insulating layer made of an epoxy resin, and the rubbing treatment is directly performed on the organic insulating layer. With both functions. The tilt angle is 0.5 degrees.

(4) When the electro-optical characteristics in this example were measured, display characteristics that were almost the same as those in Example 1 were obtained. Further, as in Example 4, the liquid crystal alignment was good even though the tilt angle was as small as 0.5 degree, and no alignment defect domain was generated.

[Example 7]
The epoxy resin used for the protective film in Example 6 was similarly changed to polyimide which would be an organic insulating layer.

(4) When the electro-optical characteristics in this example were measured, display characteristics that were almost the same as those in Example 1 were obtained. In addition, the tilt angle slightly increased to 2.0 degrees as compared with Example 6. The liquid crystal alignment was good, and no alignment failure domain was generated.

[Examples 8 to 12]
The configuration of these embodiments is the same as that of the seventh embodiment except for the following requirements.

In Example 8, the major axis directions (rubbing directions) of the liquid crystal molecules on the upper and lower interfaces are substantially parallel to each other, and the angle formed with the direction of the applied electric field is 89.5 degrees (φ _LC1 = φ _LC2 = 89.5 °). The polarization transmission axis of the polarizing plate was substantially parallel to the rubbing direction (φ _P1 = 89.5 °), and the other was perpendicular to it (φ _P2 = −0.5 °).

Similarly, in Example 9, φ _LC1 = φ _LC2 = φ _P1 = 88 ° and φ _P2 = −2.0 °.

Similarly, in Example 10, φ _LC1 = φ _LC2 = φ _P1 = 75 ° and φ _P2 = −25 °.

Similarly, in Example 11, φ _LC1 = φ _LC2 = φ _P1 = 45 ° and φ _P2 = −45 °.

Similarly, in Example 12, φ _LC1 = φ _LC2 = φ _P1 = 30 ° and φ _P2 = −60 °.

FIG. 7 shows the measurement results of the electro-optical characteristics in these examples. In this case, the brightness is expressed as a normalized value in which the maximum is 100% and the minimum is 0% when the applied voltage is in the range of 0 to 10 volts (effective value Vrms). By increasing the angle φ _LC , the threshold characteristic curve tended to be steeper. To perform the halftone display with a large voltage margin, it is _sufficient to reduce φ _LC , but the brightness tends to decrease when the angle is 45 degrees or less. The optimum value of the angle φ _LC depends on the number of halftone levels to be displayed, the required value for brightness, the driving voltage, and whether or not a voltage is applied to the common electrode. The designer can control the threshold characteristics over a large range by selecting φ _LC . In consideration of brightness, it is desirable to set φ _LC to 45 degrees or more. It is even more desirable that the angle be between 60 degrees and 89.5 degrees.

When the viewing angle characteristics were measured, the difference between the curves when the viewing angle was changed left and right and up and down was very small, and the display characteristics were hardly changed, as in Example 1. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Examples 13 to 16]
The greatest difference between the above embodiment and this embodiment is that the value of the dielectric anisotropy of the liquid crystal composition layer was made negative and the rubbing direction was changed accordingly. Δε is -4.8, Δn is 0.0437
(589 nm, 20 ° C.) nematic liquid crystal composition (ZLI-2806, manufactured by Merck) was used. In each of Examples 13 to 16, the major axis directions of the liquid crystal molecules (rubbing directions φ _LC1 and φ _LC2 ) on the upper and lower interfaces are almost parallel to each other (φ _LC1 = φ _LC2 ), and the directions of the applied electric field and The angle φ _LC1 formed was in a range of more than 0 degree and less than 45 degrees. The polarization transmission axis (φ _P1 ) of one of the polarizing plates was substantially parallel to the rubbing direction, and the other (φ _P2 ) was orthogonal to the rubbing direction.

That is, in Example 13, φ _LC1 = φ _LC2 = φ _P1 = 1.5 ° and φ _P2 = −88.5 °.

In Example 14, φ _LC1 = φ _LC2 = φ _P1 = 15 ° and φ _P2 = −75 °.

In Example 15, φ _LC1 = φ _LC2 = φ _P1 = 30 ° and φ _P2 = −60 °.

In Example 16, φ _LC1 = φ _LC2 = φ _P1 = 45 ° and φ _P2 = −45 °.

The gap d was 6.3 μm when the liquid crystal was sealed, and Δn · d was 0.275 μm. The conditions other than the structure of the thin film transistor and the electrode are the same as those of the third embodiment.

FIG. 11 summarizes the measurement results of the electro-optical characteristics in these examples. Contrary to the case where the dielectric anisotropy is positive, the curve of the threshold characteristic tends to be steeper as the angle φ _LC is reduced. To perform the halftone display with a large voltage margin, it is _sufficient to increase φ _LC , but when the angle exceeds 45 degrees, the brightness tends to decrease. As in the case where the dielectric anisotropy is positive, the optimal value of the angle φ _LC depends on the number of halftone levels to be displayed, the required value for brightness, the driving voltage, and whether to apply a voltage to the common electrode. Be replaced by The designer can control the threshold characteristics over a large range by selecting φ _LC . In consideration of brightness, it is more preferable to set φ _LC to 45 degrees or less.

When the viewing angle characteristics were measured, the difference between the curves when the viewing angle was changed to the left, right, up and down was very small, and the result was that the display characteristics hardly changed in any case, as in Example 1. In particular, no reversal of the level in the case of halftone display (8 gradations) was observed at all in the range of ± 50 degrees both up and down and left and right. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Examples 17 to 19]
In the present embodiment, Example 14 (φ _LC1 = φ _LC2 = φ _P1 = 15 °, φ _P2 = −75 °) having the best characteristics in Examples 13 to 16 was compared with the liquid crystal molecule long axis direction. The polarizing plate arrangement was the same, and the product d · Δn of the thickness d of the liquid crystal composition layer and the refractive index anisotropy Δn was changed. The thickness d of each of the liquid crystal composition layers in Examples 17, 18, and 19 was 4.0, 4.9, and 7.2 μm, that is, d · Δn was 0.1748, 0.2141, and 0.3146 μm, respectively. Here, while the refractive index anisotropy Δn was fixed and only the thickness d of the liquid crystal composition layer was changed, other liquid crystal display methods (for example,
As in the case of the 90-degree twisted nematic method, the same result is obtained for the optimum value of the brightness even when the refractive index anisotropy Δn is changed. Similar results are obtained even when the value of the dielectric anisotropy of the liquid crystal composition layer is made positive. The results, including the results of Example 14, are collectively shown in FIG. 12 (a) shows the applied voltage on the horizontal axis, and FIG. 12 (b) shows the applied voltage fixed at 7 volts in FIG. 12 (a) and the horizontal axis shows d · Δn. As is clear from FIG. 12B, the brightness strongly depends on d · Δn, and there is an optimum value. In order to increase the brightness to 30% or more, which is practical, it is sufficient to set d · Δn between 0.21 and 0.36 μm, and to further increase the brightness to 50% or more, 0.23 to 0.33 μm. It should be between. Further, in consideration of mass productivity such as control of the liquid crystal encapsulation time and the thickness of the liquid crystal composition layer, it is desirable that the value of d be 5.0 μm or more and Δn be 0.08 or less as in this embodiment.

[Examples 20 to 22]
As is clear from the results of Examples 17 to 19, the optimum value of d · Δn is between 0.21 and 0.36 μm, preferably between 0.23 and 0.33 μm. In view of the fact that the thickness of the mass-producible liquid crystal composition layer is 5.0 μm or more, the value of the refractive index anisotropy Δn must be 0.072 or less, preferably 0.066 or less. However, there are very few types of liquid crystal compounds having such a very low Δn, and it is difficult to sufficiently achieve compatibility with other practically required characteristics. Therefore, d · Δn of the liquid crystal composition layer is set to be slightly higher, and an optical anisotropic medium having a phase difference Rf lower than d · Δn of the liquid crystal composition layer is determined to exceed the optimum value. The liquid crystal composition layer is inserted so as to compensate for the phase difference, and as a result, the effective phase difference between the liquid crystal composition layer and the optically anisotropic medium is an optimum value from 0.21 to 0.2. A method was devised so as to be within 36 μm.

In Examples 20 to 22, the configuration was the same as Example 3 except for the following conditions. The thicknesses of the liquid crystal composition layers were 5.0, 5.2, and 5.5 μm, respectively. The refractive index anisotropy Δn is 0.072 (589
nm, 20 ° C.), the value of d · Δn is 0.360,
0.3744, 0.396 μm. In this state, since the brightness and the color tone are higher than the good range of 0.21 to 0.36 μm, the color is orange. An optically anisotropic medium of a uniaxially stretched film made of polyvinyl alcohol was laminated on the liquid crystal cell so as to compensate for the birefringence phase difference of the liquid crystal during low voltage driving (here, 0 volt). That is, φ _{R is set} to 85 degrees, which is the same as φ _LC1 (= φ _LC2 ). The phase difference Rf is 0.07, 0.08, 0.10 μm, respectively, and the value of (d · Δn−Rf) is 0.29, 0.304, 0.296 μm, which is 0.21 with good brightness and color tone. From 0.36 μm.

As a result, a bright display with no coloration and a brightness of 50% or more was obtained.

[Example 23]
A nematic liquid crystal composition having a negative dielectric anisotropy Δε, a value of −2.5, and a Δn of 0.0712 (589 nm, 20 ° C.) (manufactured by Merck Ltd., ZLI-
4518). Other configurations are the same as those of the fourteenth embodiment except for the following. The thickness of the liquid crystal composition layer is 5.5 μm, that is, d · Δn is 0.3916 μm. An optically anisotropic medium of a uniaxially stretched film made of polyvinyl alcohol having a phase difference Rf of 0.11 μm is laminated on the liquid crystal cell, and the value of (d · Δn−Rf) is 0.2816 μm, and the brightness and color tone are good. It was set to fall within a range of 0.21 to 0.36 μm.

As a result, a bright display with no coloration and a brightness of 50% or more was obtained.

[Example 24]
The configuration of the present embodiment is the same as Embodiment 8 except for the following requirements.

The Δn of the liquid crystal composition layer was 0.072 and the gap d was 7.0 μm. Therefore, Δn · d is 0.504 μm. φ _LC1 was 89.5 degrees, and the liquid crystal molecule alignment directions on the upper and lower substrates were intersected with each other, and | φ _LC1 −φ _LC2 | = 90 degrees. The polarizers are arranged orthogonally (| φ _P2 −
φ _P1 | = 90 °), and φ _LC1 = φ _P1 so that the relationship with the liquid crystal molecule alignment direction becomes an optical rotation mode. As a result, a normally open type was obtained.

When the electro-optical characteristics in this embodiment were measured, the brightness was also 50% except that the threshold voltages V ₁₀ and V ₉₀ were approximately doubled as compared with the other embodiments in the birefringence mode. As described above, the difference between the curves when the viewing angle is changed left and right and up and down is extremely small, and the result is that the display characteristics hardly change. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Examples 25 and 26]
The configuration of this embodiment is the same as that of the first embodiment except for the following requirements.

The arrangement of the polarizing plates was set so that a dark state was obtained when the electric field was slightly applied instead of 0. That is, | φ _LC1 −φ _P1 | was set to 5 degrees and 15 degrees in Examples 25 and 26, respectively, and | φ _P2 −φ _P1 | = 90 degrees.

同 じ く As in the other examples, good display characteristics were obtained in both the brightness and the viewing angle. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Examples 27 and 28]
The configuration of this embodiment is the same as that of the fourteenth embodiment except for the following requirements.

The arrangement of the polarizing plates was set so that a dark state was obtained when the electric field was slightly applied instead of 0. That is, | φ _P1 −φ _LC1 | was set to 5 degrees and 7 degrees in Examples 27 and 28, respectively, and | φ _P2 −φ _P1 | = 90 degrees. The thickness d of the liquid crystal composition layer was 6.3 μm. Therefore, Δn · d is 0.275 μm.

FIG. 13 shows the measurement results of the electro-optical characteristics in this example. In the case of Example 27, the voltage V _{OFF at which the} state becomes dark was 3.0 volts, and the voltage V _ON at which the state became brightest was 9.2 volts. If the driving is performed between V _OFF and V _ON , a sufficiently high contrast can be obtained. Similarly, in the case of Example 28, V _OFF was 5.0 volts and V _ON was 9.0 volts.

When driven between V _OFF and V _ON , as in the other examples, good display characteristics were obtained in both brightness and viewing angle. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Example 29]
The configuration of this embodiment is the same as that of the twenty-seventh embodiment except for the following requirements.

画像 An image signal was applied to the signal electrode, and an AC waveform of 3.0 V was applied to the common electrode. As a result, the voltage supplied to the signal electrode has been reduced (from 8.3 V to 6.2 V).

Driving was performed between V _OFF and V _ON in this manner, and good display characteristics were obtained in both the brightness and the viewing angle as in the other examples. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Example 30]
The configuration of this embodiment is the same as that of the first embodiment except for the following requirements.

The arrangement of the polarizing plates was set so that a dark state was obtained when an electric field was applied instead of 0. That is, | φ _LC1 −φ _P1 | was set to 45 degrees, and | φ _P2 −φ _P1 | was set to 90 degrees. This resulted in a bright state when a low voltage was applied and a dark state when a high voltage was applied. The measurement result of the voltage dependency of the brightness at this time is shown by a solid line in FIG.

同 じ く As in the other examples, good display characteristics were obtained in both brightness and viewing angle. The contrast ratio was 35. In addition, the liquid crystal alignment was good, and no alignment failure domain was generated.

[Example 31]
In the structure of Example 30, a birefringent medium (uniaxially stretched polyvinyl alcohol film) for compensating for an interface residual retardation was inserted between two polarizing plates. The stretching direction phi _R of the film was set to -45 °, it was perpendicular to the polarizer transmission axis. The phase difference Rf is 15 nm.

光 As shown by the dotted line in FIG. 14, light leakage when a high voltage was applied was suppressed, and the contrast ratio was further improved to 150, as compared with Example 30.

FIG. 4 is a diagram illustrating an operation of a liquid crystal in the liquid crystal display device of the present invention. FIG. 4 illustrates an example of a thin film transistor of the present invention. FIG. 6 is a diagram showing electro-optical characteristics (viewing angle direction dependence) of the present invention (a) and comparative example (b). FIG. 3 is a diagram showing an embodiment of the present invention in which a pixel electrode (source electrode), a common electrode, a scanning electrode, and a signal electrode (drain electrode) are all arranged on one substrate in a thin film transistor. FIG. 4 is a diagram showing an embodiment of the present invention in which a pixel electrode (source electrode) and a signal electrode (drain electrode) are arranged at the center of a pixel, and one pixel is divided into two. Shows with respect to the electric field direction, the long molecular axis orientation direction phi _LC on the interface, a polarizing plate polarizing axis phi _P, the angle of the phase plate fast axis phi _R. FIG. 9 is a view showing electro-optical characteristics in various examples in which the molecular long axis alignment direction φ _LC on the interface is changed. When the dielectric anisotropy is positive. FIG. 1 is a diagram illustrating a liquid crystal display drive circuit system of the present invention. FIG. 1 is a diagram illustrating a liquid crystal display transmission type optical system according to the present invention. FIG. 1 is a diagram illustrating a liquid crystal display reflective optical system of the present invention. FIG. 9 is a view showing electro-optical characteristics in various examples in which the molecular long axis alignment direction φ _LC on the interface is changed. When the dielectric anisotropy is negative. The figure which shows the electro-optic property in the various examples which changed thickness d of the liquid crystal composition layer. When the dielectric anisotropy is negative. The figure which shows the electro-optic characteristic when the arrangement | positioning of a polarizing plate is set so that a dark state may be obtained in the state where the electric field was slightly applied rather than 0. FIG. 9 is a diagram illustrating characteristics of a normally open type and characteristics when an interface residual phase difference is compensated.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Pixel electrode (source electrode), 2 ... Common electrode (common electrode), 3 ... Substrate, 4 ... Alignment control film, 5 ... Liquid crystal molecules in a liquid crystal composition layer, 6 ... Polarizing plate, 7 ... Electric field direction, 8 ... direction of molecular long axis orientation (rubbing direction) on interface, 9 ... direction of polarization axis of polarizing plate, 10 ... gate electrode (scanning electrode),
DESCRIPTION OF SYMBOLS 11 ... Additional capacitance element, 12 ... Signal electrode (drain electrode), 13 ... Gate insulating film, 14 ... Flattening film, 15 ... Protective insulating film, 16 ... Amorphous silicon, 17 ... Color filter, 18 ... Light shielding layer, 19 ... Polarizing plate polarized light transmission axis, 20: phase difference plate fast axis, 21: signal electrode driving circuit, 22: scanning electrode driving circuit, 23: signal electrode, 24: scanning electrode, 25: lower substrate, 26: upper substrate, 27: control circuit, 28: retardation plate, 29: backlight, 30: reflector, 31: liquid crystal composition layer.

Claims (18)

In a liquid crystal display device having a plurality of thin film transistors,
A pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and at least one of the pair of substrates is provided with an electric field having a component predominantly parallel to one of the pair of substrates. Having an electrode structure formed to generate a non-conductive layer formed in contact with the liquid crystal layer, and a color filter disposed on the layer of the non-conductive layer,
A liquid crystal display device characterized in that a surface of the non-conductive layer in contact with the color filter planarizes the color filter, and a surface in contact with the liquid crystal layer controls alignment of liquid crystal in the liquid crystal layer. In claim 1,
The liquid crystal display device, wherein the color filter is formed on a substrate facing a substrate on which the electrode structure is formed. In a liquid crystal display device including a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and a plurality of thin film transistors,
A plurality of common electrodes and at least one pixel electrode are formed between each of the common electrodes on one of the pair of substrates, and the pair of substrates is provided between the pixel electrodes and the plurality of common electrodes. Voltage is applied such that an electric field predominantly parallel to one of the substrates is generated,
A color filter is formed on the other of the pair of substrates, an insulating film is formed on the color filter,
A liquid crystal display device, wherein a surface of the insulating film in contact with the color filter planarizes the color filter, and a surface of the insulating film in contact with the liquid crystal layer controls alignment of liquid crystal molecules in the liquid crystal layer in a predetermined direction. 液晶 A liquid crystal display device according to at least one of claims 1 to 3, wherein the non-conductive layer has at least one organic polymer layer. The liquid crystal display device according to claim 4, wherein the organic polymer layer contains an epoxy resin. The liquid crystal display device according to claim 4, wherein the organic polymer layer contains a polyimide resin. 液晶 The liquid crystal display device according to at least one of claims 1 to 3, wherein the non-conductive layer has at least one inorganic layer. The liquid crystal display device according to claim 1, wherein an inclination angle of liquid crystal molecules at an interface between the liquid crystal layer and the non-conductive layer with respect to the pair of substrates is 4 degrees or less. The liquid crystal display device according to claim 8, wherein an inclination angle of liquid crystal molecules at an interface between the liquid crystal layer and the non-conductive layer with respect to the pair of substrates is 2 degrees or less. In a liquid crystal display device having a plurality of thin film transistors,
A pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, an electrode structure for generating an electric field having a component predominantly parallel to the substrate in the liquid crystal layer, the electrode structure and the plurality of electrodes. Having an insulating film formed on the thin film transistor,
A liquid crystal display device, wherein one surface of the insulating film in contact with the liquid crystal layer controls alignment of liquid crystal molecules in the liquid crystal layer. The liquid crystal display device according to claim 10, wherein the other surface of the insulating film in contact with the plurality of thin film transistors flattens the thin film transistors. In a liquid crystal display device having a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates,
One of the pair of substrates has a plurality of scanning wiring electrodes, a plurality of signal wiring electrodes formed so as to intersect the plurality of scanning wiring electrodes in a matrix, and a plurality of scanning wiring electrodes and the plurality of scanning wiring electrodes. A plurality of thin film transistors formed corresponding to intersections with wiring electrodes, a plurality of pixel electrodes connected to the thin film transistors, a common electrode formed in parallel with the plurality of signal wiring electrodes, the liquid crystal layer, Having an insulating film in contact with the thin film transistor,
A voltage is applied between the common electrode and the pixel electrode so that an electric field predominantly parallel to one of the pair of substrates is generated,
A liquid crystal display device, wherein a surface of the insulating film in contact with the plurality of thin film transistors planarizes the color filter, and a surface in contact with the liquid crystal layer controls alignment of liquid crystal molecules of the liquid crystal layer in a predetermined direction. A liquid crystal display device according to at least one of claims 10 to 12, wherein the insulating film has at least one organic polymer layer. 14. The liquid crystal display device according to claim 13, wherein the organic polymer contains an epoxy resin. 14. The liquid crystal display device according to claim 13, wherein the organic polymer includes a polyimide resin. The liquid crystal display device according to at least one of claims 10 to 12, wherein the insulating film has at least one inorganic layer. 13. The liquid crystal display device according to claim 10, wherein an inclination angle of liquid crystal molecules at an interface between the liquid crystal layer and the insulating film with respect to the pair of substrates is 4 degrees or less. 18. The liquid crystal display device according to claim 17, wherein an inclination angle of liquid crystal molecules at an interface between the liquid crystal layer and the non-conductive layer with respect to the pair of substrates is 2 degrees or less.

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