JPH11160716A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high-contrast display which is stable in an alignment state on spacer peripheries, is highly reliable against a process fluctuation, vibration and impact and is lessened in display unevenness by subjecting spacers to a perpendicular alignment treatment or horizontal alignment treatment. SOLUTION: The spacers BZ of the liquid crystal display device are subjected to the perpendicular alignment treatment or horizontal alignment treatment. The initial alignment state of the liquid crystal molecules LK near the central part of the liquid crystal layer at the spacer (bead) BZ surface in a non- impression state of an electric field EDR attains the state radially arrayed from the center of the spacers BZ viewing in plane. The state of light leakage is nearly zero in the rubbing direction RDR and the direction perpendicular to the rubbing direction (a). At the time of the impression of the electric field EDR, the liquid crystal molecules LK are realigned with a twist of max. 45 deg. with respect to the rubbing direction RDR but the region where the alignment direction of the liquid crystal molecules LK changes by >=45 deg. decreases the further from the spacers BZ and the adverse influence of the light leakage is negligible (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to an in-plane switching type active matrix type liquid crystal display device having high contrast, good viewing angle characteristics, and low luminance unevenness.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device using an active element typified by a thin film transistor (TFT) is thin and lightweight, and is comparable to a cathode ray tube. From the point of high image quality, it is becoming widespread as a display terminal of OA equipment and the like.

Recently, an electric field substantially parallel to a substrate is formed between two kinds of electrodes formed on one of a pair of substrates, and a liquid crystal (hereinafter, also referred to as a liquid crystal composition) is operated by the electric field, whereby the two kinds of electrodes are operated. The method of modulating and displaying the light incident on the liquid crystal through the gap between the electrodes (hereinafter referred to as the horizontal electric field method or the in-plane switching method) has a feature that the viewing angle is extremely wide. It is attracting attention as a leading technology for liquid crystal display devices.

The main features of this system are mainly that of Japanese Patent Application Laid-Open No. 5-505247 and Japanese Patent Publication No. 63-219.
No. 07 and JP-A-6-160878.

[0005]

However, in the active matrix type liquid crystal display device described in the above-mentioned publications relating to the above-mentioned in-plane switching method, the thickness of the liquid crystal layer, that is, the alignment around the spacer for maintaining the so-called cell gap, is not considered. Since the alignment state of the liquid crystal around the spacer is disturbed without being considered, the light transmission state around the spacer is different from other parts, and there is a problem that display is adversely affected. As this kind of spacer, a spherical spacer (hereinafter, also referred to as a spacer bead or simply a bead or a spacer) is generally used.

FIG. 14 is a plan view showing an example of light leakage around a spherical spacer bead BZ generated between two electrodes without applying an electric field EDR in a conventional in-plane switching mode liquid crystal display device.

For example, in a conventional in-plane switching type liquid crystal display device, a voltage is applied between a strip-shaped opaque pixel electrode PX and an opaque counter electrode CT which are parallel to each other to apply a voltage to a substrate surface (not shown). An electric field EDR is generated in a direction substantially parallel to and perpendicular to the direction in which the electrodes extend.

Further, for example, the rubbing direction RDR is the same on the upper and lower substrates, and the alignment film is rubbed.
Further, for example, the light transmission axis of the lower polarizing plate is in the rubbing direction RD.
R and the light transmission axis of the upper polarizing plate is shifted by about 90 degrees (crossed Nicols arrangement). Thus, the electric field ED
A so-called normally black mode in which dark (black) BLK is displayed without applying R can be configured.

However, in the conventional configuration, as shown in FIG. 14, it has been found that light leakage LK from the side of the spacer BZ is large and the display contrast is significantly reduced.

FIG. 15 is a plan view showing an example of a light leakage portion LK in the rubbing direction RDR observed in a conventional liquid crystal display device.

That is, when observing the state of light leakage LK in the vicinity of each spherical bead BZ, a spherical type covering the entire periphery of the spherical bead BZ or two crescent-shaped types spreading over the rubbing direction RDR is constituted. It turned out that it was. In particular, in the two crescent type,
A tendency was observed that the area of light leakage increased as the dark display portion between each crescent pattern shifted from the rubbing direction.

As a presumed cause of these light leaks, the alignment state of the liquid crystal around the spacer is disturbed by the influence of the spacer surface. Therefore, the light transmission state around the spacer is different from other parts, and the display influences the display. Is considered to have given.

In particular, since the spacer surface is not subjected to the alignment treatment, when the conventional spacer is used, the alignment regulating force of the spacer with respect to the liquid crystal molecules is small. It changes easily due to impact or the like, and when no electric field is applied, spherical beads B as shown in FIG.
Light leakage of a spherical type covering the entire periphery of Z or two crescent-shaped types covering the rubbing direction RDR appeared, increasing the amount of light leakage and deteriorating the display quality, particularly the contrast.

An object of the present invention is to provide a horizontal electric field type liquid crystal display device of high contrast display with stable orientation state around the spacer, high reliability against process fluctuation, vibration and shock, and small display unevenness. To provide.

[0015]

To achieve the above object, the present invention uses the following means.

(1) A pair of opposed insulating substrates, at least one of which is transparent, a pair of alignment films formed between the pair of insulating substrates, a spacer and a liquid crystal composition sandwiched between the pair of alignment films. And a liquid crystal display device having a pixel electrode and a counter electrode for applying an electric field having a component substantially parallel to the insulating substrate surface, and at least one polarizing plate, wherein the spacer is vertically or horizontally aligned. It is characterized by being.

(2) A pair of opposed insulating substrates at least one of which is transparent; a pair of alignment films which are rubbed between the pair of insulating substrates in a direction substantially parallel or intersecting with each other; A liquid crystal display device having a spacer and a liquid crystal composition interposed therebetween, a pixel electrode and a counter electrode for applying a horizontal electric field substantially parallel to the insulating substrate surface, and a pair of polarizing plates interposing the pair of insulating substrates. In the state where the electric field is not applied, when observed from the vertical direction of the display surface of the liquid crystal display device, each φF formed by the direction of a portion where there is substantially no light leakage near the spacer and the initial alignment direction by the rubbing process. Is zero or ± 45
It is characterized in that the surface of the spacer is subjected to an orientation treatment so as to be within the degree.

(3) A pair of opposed insulating substrates, at least one of which is transparent; a pair of alignment films which are rubbed in a direction substantially parallel or intersecting between the pair of insulating substrates; A liquid crystal display device having a spacer and a liquid crystal composition interposed therebetween, a pixel electrode and a counter electrode for applying a horizontal electric field substantially parallel to the insulating substrate surface, and a pair of polarizing plates interposing the pair of insulating substrates. Wherein the surface of the spacer is subjected to an orientation treatment such that light leakage near the spacer is reduced to four places or four or more places in a state where the electric field is not applied.

(4) In the above (1), (2) or (3), spherical beads are used as the spacer.

(5) In the above (1), (2) or (3), the liquid crystal composition has a positive dielectric anisotropy.

(6) In the above (2) or (3), the light transmission axes of the pair of polarizers form an angle of 90 ° or 90 ± 10 ° with each other, and the light transmission axis of the upper or lower polarizer. The shaft is coincident with the upper or lower rubbing direction.

According to the above-mentioned means (1) to (6), when beads having an alignment treatment layer provided on the surface thereof or beads subjected to an alignment treatment are used as the spacers, the liquid crystal alignment on the bead surface is stabilized. In particular, in the case of beads that have been appropriately oriented, the area around which the orientation changes can be reduced, so that light leakage is reduced and high contrast is obtained.

In the following description, a case will be described in which the obtained molecules having a homogeneous initial orientation are displayed in a birefringence mode.

FIG. 9 is a diagram for explaining the operation principle of the in-plane switching mode liquid crystal display device according to the present invention.
(B) is a sectional view, and (c) and (d) are plan views.

SUB1 and SUB2 are insulating substrates,
CT is a counter electrode, PX is a pixel electrode, DL is a data line, PSV is an insulating layer, BM is a black matrix, FI
L is a color filter, OC is an overcoat layer, ORI
1, ORI2 is an alignment film, POL1 and POL2 are polarizing plates,
LC indicates a liquid crystal layer, RDR indicates a rubbing direction, EDR indicates an electric field direction, and MAX1 and MAX2 indicate the maximum transmission axis directions of the respective polarizing plates.

As described in detail in JP-A-6-160878, the light transmittance T / T ₀ when a liquid crystal panel is inserted between two polarizing plates in which a uniaxial birefringent medium is arranged orthogonally is generally known. It is expressed by the following equation.

T / T ₀ = sin ² (2χ _eff ) · sin ² (πd _eff · Δn / λ) (1) where χ _eff is the effective optical axis direction (light Angle between the axis and the polarization transmission axis), d _eff is the effective thickness of the liquid crystal composition layer having birefringence, Δn is the refractive index anisotropy, λ
Represents the wavelength of light.

Here, in order to obtain a normally-closed characteristic in which a dark display is obtained when a low voltage VL is applied between the electrodes and a bright display is obtained when a high voltage HL is applied, the arrangement of one of the polarizing plates is required. Initial alignment direction (rubbing direction R) of liquid crystal molecules whose light transmission axis (or light absorption axis) is homogeneously aligned
DR), that is, φP1 ≒ φLC1 = φL
C2, and the light transmission axis of the other polarizing plate is perpendicular to this, that is, φP2 = φP1 + 90 degrees.

The initial alignment state of the liquid crystal molecules homogeneously aligned in a specific direction in the plane is determined by the alignment films OR1 and OR2.
Are rubbed in directions parallel or anti-parallel to each other. The above antiparallel direction means a parallel direction having a different direction.

In the case of the lateral electric field system having this configuration, since χ _eff = 0 in equation (1), the light transmittance T / T ₀ is ideally zero when no electric field EDR is applied. On the other hand, when an electric field is applied, the value of _{eff eff} increases according to the intensity, and the light transmittance T / T ₀ becomes maximum at 45 degrees.

That is, by applying the electric field EDR, the alignment direction of the liquid crystal molecules LC in the liquid crystal layer at the center is substantially parallel to the substrate plane as shown in FIGS. 9B and 9D. From the rubbing direction RDR, in this example, the display image is rotated clockwise (twisted) and rotated about 45 degrees, and the display image shows the maximum transmittance.

First, the case where vertically oriented beads are used will be described.

FIGS. 2A and 2B are plan views schematically showing the alignment state of the liquid crystal molecules LC around the vertical alignment beads when no electric field is applied and when the electric field EDR is applied. FIG.
(B) shows the alignment state of the liquid crystal molecules near the center of the liquid crystal layer around the vertical alignment beads when the electric field EDR is applied.

FIGS. 3A and 3B are cross-sectional views showing the alignment state of liquid crystal molecules between the alignment films ORI1 and ORI2. FIG. 3A is a cross-sectional view taken along the line AA 'in FIG. FIG. 3 shows a cross-sectional view along the line BB ′ of FIG. 2.

As shown in FIG. 3A, in the cross section in the rubbing direction RDR, the liquid crystal molecules near the spacers (beads) are aligned from the spacer surface in the direction perpendicular to the surface in the portion near the alignment film surface. Although a regulating force acts, the pretilt (Pretil) is almost parallel to the film surface from the alignment film.
t) Since a regulating force acts on the alignment, the two are combined and the tilt angle is slightly increased. On the other hand, it is considered that the initial orientation direction in the plane is almost the same as that of the liquid crystal molecules at a portion away from the spacer.

On the other hand, as shown in FIG. 3B, in the cross section perpendicular to the rubbing direction RDR, the alignment of the bead surface and the alignment of the liquid crystal interfere with each other, and the liquid crystal molecules in the vicinity of the spacer face the surface of the spacer. Is considered to be in a state of being twisted by 90 degrees with respect to the rubbing direction due to the restricting force in the vertical direction.

Therefore, as shown in FIG. 2A, when no electric field EDR is applied, the initial alignment state of the liquid crystal molecules near the center of the liquid crystal layer on the bead surface is the same as that of the bead. It is considered that the state is arranged radially from the center.

According to equation (1), the state of light leakage is χ _eff = 0 in the rubbing direction and in the direction perpendicular to the rubbing direction.
Degrees or 90 degrees, the light transmittance T / T ₀ becomes almost zero. On the other hand, the portion where the orientation direction of the liquid crystal molecules is inclined at 45 degrees or -45 degrees with respect to the rubbing direction is considered to correspond to the portion where light leaks most as shown in FIG. Can be That is, the light leakage portion LK
Is composed of four light leak portions when an ideal vertical alignment process is performed.

When an electric field is applied, as shown in FIG. 2B, the liquid crystal molecules are twisted by a maximum of about 45 degrees with respect to the rubbing direction and realigned by the electric field. The region where the orientation direction changes by 45 degrees or more is reduced, and because of the normally black characteristic, the transmittance becomes brighter as the electric field is increased, so that the adverse effect of light leakage can be ignored.

From the above, when the vertically aligned beads are used, in an ideal state, the liquid crystal molecules which are homogeneously initially aligned and have almost no twist can be displayed in the birefringence mode with normally black characteristics. Then 4
It can be seen that a portion having almost no light leakage occurs at the portion, and the display contrast is significantly reduced compared to beads without alignment treatment.

Furthermore, even when an electric field is applied, in the case of the lateral electric field method, the liquid crystal alignment at the center of the liquid crystal layer is almost parallel to the substrate surface as shown in FIG. It can be seen that when used, the orientation disorder near the beads is very small.

Next, the case where the beads subjected to the horizontal alignment treatment are used will be described.

The alignment state of the liquid crystal molecules LC around the horizontal alignment bead will be described for convenience in two modes.

FIGS. 4 and 5 schematically show the alignment state of the liquid crystal molecules LC around the horizontally aligned beads in mode 1. FIG.

FIG. 4A schematically shows the state of the liquid crystal molecules near the center of the liquid crystal layer around the horizontal alignment beads in mode 1 when no electric field is applied, and FIG. 4B shows the state when the electric field EDR is applied. FIG.

FIG. 5A and FIG.
FIG. 3A is a cross-sectional view schematically illustrating an alignment state of liquid crystal molecules between alignment films ORI1 and ORI2 along an AA ′ cutting line and a BB ′ cutting line in FIG.

As shown in FIG. 5A, the rubbing direction R
In the DR cross section, the liquid crystal molecules in the vicinity of the spacer are parallel to the spacer surface and parallel to the alignment film surface, but exert a restricting force in a direction different from the rubbing direction by 90 degrees.

Thus, as one moves away from the spacer,
When the initial alignment direction of the liquid crystal molecules parallel to the substrate surface changes by about 90 degrees from the state parallel to the surface of the spacer, a portion where the alignment state is disturbed occurs.

On the other hand, as shown in FIG. 5 (b), in the cross section perpendicular to the rubbing direction RDR, the alignment state of the liquid crystal molecules near the spacer also indicates the regulating force from the alignment film and the spacer surface. It is aligned with the regulating force and is aligned similarly to liquid crystal molecules separated from the spacer.

Therefore, as shown in FIG.
When no electric field EDR is applied, the initial alignment direction of the liquid crystal molecules near the center of the liquid crystal layer on the bead surface is almost in the shape of a quincline from the center of the bead if the parallel alignment regulating force on the bead surface is stronger than the regulating force generated by rubbing. Therefore, it is considered that the state is arranged in parallel with the alignment film surface.

According to the equation (1), the state of light leakage is χ _eff = 0 ° or 90 ° in the rubbing direction and in the direction perpendicular to the rubbing direction, as in the case of the vertically oriented beads. T / T ₀ becomes almost zero. On the other hand, the alignment direction of the liquid crystal molecules is 45 degrees or -4 with respect to the rubbing direction.
In the portion inclined at 5 degrees, light leaks most at this portion as shown in FIG. That is, the light leakage portion LK is composed of four light leakage portions when the ideal parallel alignment processing of mode 1 is performed.

When no voltage is applied, as shown in FIG. 4B, the liquid crystal molecules are moved up to about 45 degrees in the rubbing direction by the electric field.
Twist and reorient, but as you move away from the spacer,
The region where the orientation direction of the liquid crystal molecules changes by 45 degrees or more is reduced, and because of the normally black characteristic, the transmittance becomes brighter as the electric field is increased, so that the adverse effect of light leakage can be ignored.

As described above, when the ideal mode 1 alignment beads are used, similarly to the case where the vertical alignment beads are used, in the ideal state, the homogeneous initial alignment liquid crystal molecules having almost no twist can be used. When the display is performed in the birefringence mode of the Mariblack characteristic, when no electric field is applied, four light-leakage portions are almost generated, and it can be seen that the display contrast is greatly improved as compared with the beads without alignment treatment. In addition, there is a tendency that the light leakage portion is further reduced as compared with the case where the vertically aligned beads are used. Furthermore,
Even when an electric field is applied, in the case of the horizontal electric field method, the liquid crystal alignment at the center of the liquid crystal layer is almost parallel to the substrate surface as shown in FIG. It can be seen that the disturbance of the orientation near the beads is very small.

Next, FIGS. 6 and 7 schematically show the alignment state of the liquid crystal molecules LC around the horizontal alignment beads in mode 2. FIG.

That is, FIG. 6A schematically shows the state of the liquid crystal molecules near the center of the liquid crystal layer around the horizontal alignment beads in mode 2 when no electric field is applied, and FIG. 6B shows the state when the electric field EDR is applied. FIG.

FIGS. 7A and 7B are schematic diagrams showing the alignment state of liquid crystal molecules between the alignment films ORI 1 and ORI 1 along the cutting line AA ′ and the cutting line BB ′ in FIG. 6A. FIG.

As shown in FIG. 7A, in the cross section in the rubbing direction RDR, the liquid crystal molecules in the vicinity of the spacer are parallel to the spacer surface and exert a regulating force in a direction perpendicular to the alignment film surface. It is considered that the central part of the liquid crystal layer has a tilt angle of about 90 degrees.

Therefore, as the distance from the spacer increases,
The initial alignment direction, which is a component of the director of the liquid crystal molecules parallel to the substrate surface, is substantially constant, and a part of the alignment state in which the tilt angle changes by about 90 degrees is generated.

On the other hand, as shown in FIG. 7B, in a cross section perpendicular to the rubbing direction RDR, liquid crystal molecules near the spacer are parallel to the spacer surface, and a regulating force acts in a direction perpendicular to the alignment film surface. It is considered that the center part of the liquid crystal layer has a tilt angle of about 90 degrees, and as the distance from the spacer is increased, a part of the alignment state in which the tilt angle changes by about 90 degrees while the liquid crystal molecules are twisted is generated.

Therefore, as shown in FIG.
In the state where no electric field EDR is applied, the initial alignment state of the liquid crystal molecules near the center of the liquid crystal layer on the bead surface is such that, when viewed in a plan view, the parallel alignment regulating force on the bead surface is stronger than the regulating force generated by rubbing. Therefore, it is considered that they are substantially concentric and are arranged in a direction perpendicular to the alignment film surface.

Here, since the retardation of the light passing through the vertically oriented portion is almost zero, the T
In the N and STN modes, light leaks from this portion and the display quality is degraded. However, in the case of the horizontal electric field method, since the transmission axes or absorption axes of the upper and lower polarizing plates are arranged almost orthogonally, light leakage from this portion is ideally almost eliminated. However, light leakage from this portion is ideally almost eliminated. However, in the peripheral region of this portion, as described above, since a portion in which the alignment state is disturbed occurs, as shown in FIG. _6A , the light leakage region LK occurs depending on the angle of _{eff eff} .

However, the light leakage area tends to be further reduced as compared with the case of mode 1, and higher contrast can be obtained.

When a voltage is applied, as shown in FIG. 6B, the liquid crystal molecules are twisted and rearranged by a maximum of about 45 degrees with respect to the rubbing direction due to the electric field, but the tilt of the liquid crystal molecules increases as the distance from the spacer increases. The area where the angle changes is reduced, and because of the normally black characteristic, the transmittance increases to the bright display side as the electric field increases, so that the adverse effect of light leakage can be ignored.

From the above, it can be seen that in the case where the ideal mode 2 parallel alignment beads are used, similarly to the case where the vertical alignment beads are used, in the ideal state, the homogeneous initially aligned liquid crystal molecules having almost no twist are formed. When the display is performed in the birefringence mode of normally black characteristics, when no electric field is applied, four light-leakage portions are almost generated, and it is understood that the display contrast is greatly improved as compared with beads without alignment treatment. In addition, there is a tendency that the portion of light leakage when no electric field is applied is further reduced as compared with the case where the vertically oriented beads or the mode 1 horizontally oriented beads are used.

Here, examples in which beads surface-treated with an alignment treatment agent are applied to a liquid crystal display element other than the horizontal electric field type are disclosed in Japanese Patent Publication No. 15847/1990 and Japanese Patent Laid-Open No. 5-232.
478.

That is, according to the invention disclosed in Japanese Patent Publication No. 2-15878, in a conventional type (twisted nematic type) liquid crystal display element, the distance between opposing electrodes formed between opposing upper and lower substrates (electrode substrates) is reduced. In a display element in which a spacer and a liquid crystal composition having a negative dielectric anisotropy are sandwiched in a gap, and a vertical (vertical) alignment treatment or a tilt alignment treatment is performed on an alignment film of the electrode substrate, an alignment defect portion near the spacer is removed. In order to reduce the size, a configuration is described in which the spacer is surface-treated with an organic silane-based vertical alignment treatment agent.

However, this structure is different from the horizontal electric field method of the present invention, in that a voltage is mainly applied between the electrodes and light leakage near the spacer, which is a problem when liquid crystal molecules are arranged substantially in parallel with the substrate, is mainly used. Measures. Furthermore, there is no description about the rubbing direction and the state of light leakage or the state of light leakage when no voltage is applied.

Further, in Japanese Patent Application Laid-Open No. Hei 5-232478, in a conventional TN (twisted nematic) type liquid crystal display element, a spacer and a liquid crystal composition are filled in a gap between opposing electrodes formed between opposing upper and lower substrates. Rubbing the alignment film on the surface of the electrode substrate, and twisting it in a TN mode twisted by 90 degrees or 180 to 2 degrees.
In the display of STN (super twisted nematic) mode twisted by 70 degrees, in order to reduce the defective alignment near the spacer and improve the display contrast,
A configuration is described in which the spacer is subjected to an alignment treatment, particularly a surface treatment with a vertical alignment treatment agent.

That is, unlike the horizontal electric field method of the present invention, when a voltage is applied between the electrodes, the liquid crystal molecules are arranged almost vertically to the substrate by the vertical electric field, and the light leakage near the spacer is reduced. Is remarkable. Furthermore, there is no description about the rubbing direction and the state of light leakage.

[0070]

BRIEF DESCRIPTION OF THE DRAWINGS The objects and features of the present invention and still other objects and features of the present invention will become apparent from the following description with reference to the drawings.

[Embodiment 1] An embodiment in which the present invention is applied to an active matrix type color liquid crystal display device according to an embodiment of the present invention will be described below. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

<Plan Configuration of Matrix Unit (Pixel Unit)> FIG. 10 is a plan view showing one pixel of an active matrix type liquid crystal display device to which the present invention is applied and the periphery thereof.

As shown in FIG. 10, each pixel has a scanning signal line (gate signal line or horizontal signal line) GL, a counter voltage signal line (counter electrode line) CL, and two adjacent video signal lines (drain). The signal line or the vertical signal line) is arranged in an intersecting region with the DL (in a region surrounded by four signal lines). Each pixel is a thin film transistor TFT, a storage capacitor Cst
g, the pixel electrode PX, and the counter electrode CT. The scanning signal lines GL and the counter voltage signal lines CL extend in the left-right direction in FIG. Video signal line D
L extends in the up-down direction and a plurality of Ls are arranged in the left-right direction. The pixel electrode PX is connected to the thin film transistor TFT, and the counter electrode CT is integrated with the counter voltage signal line CL.

The two vertically adjacent lines along the video signal line DL
The pixel has a configuration in which the planar configuration overlaps when the pixel is bent along the line AA in FIG. This is because the opposing voltage signal line CL is shared by two vertically adjacent pixels along the video signal line DL, and the electrode width of the opposing voltage signal line CL is increased, thereby reducing the resistance of the opposing voltage signal line CL. That's why. This makes it easy to sufficiently supply a counter voltage from the external circuit to the counter electrode CT of each pixel in the left-right direction.

The pixel electrode PX and the counter electrode CT are opposed to each other, and the electric field between each pixel electrode PX and the counter electrode CT controls the optical state of the liquid crystal LC to control the display. The pixel electrode PX and the counter electrode CT are formed in a comb shape,
Each of the electrodes is vertically elongated in the figure.

The number O (number of comb teeth) of the counter electrode CT in one pixel is equal to the number P (number of comb teeth) of the pixel electrode PX and O =
It is configured to always have the relationship of P + 1 (O = 3, P = 2 in this embodiment). This is because the counter electrode CT and the pixel electrode PX are alternately arranged, and the counter electrode CT is always adjacent to the video signal line DL. As a result, the electric field between the counter electrode CT and the pixel electrode PX changes to the video signal DL.
The lines of electric force from the video signal line DL can be shielded by the counter electrode CT so as not to be affected by the electric field generated from.

The counter electrode CT is connected to a counter voltage signal line C described later.
Since the potential is always supplied from the outside by L, the potential is stable. Therefore, there is almost no potential even when adjacent to the video signal line DL. This also allows the pixel electrode P
Since the geometric position of X from the video signal line DL is far, the parasitic capacitance between the pixel electrode PX and the video signal line DL is greatly reduced, and the fluctuation of the pixel electrode potential Vs due to the video signal voltage can be suppressed. . Thus, crosstalk (defective image quality called vertical smear) occurring in the vertical direction can be suppressed.

The electrode width of each of the pixel electrode PX and the counter electrode CT is 6 μm. The electrode width of the video signal line DL is set to 8 μm, which is slightly wider than the pixel electrode PX and the counter electrode CT in order to prevent disconnection.

On the other hand, the electrode interval between the pixel electrode PX and the counter electrode CT changes depending on the liquid crystal material used. this is,
Since the electric field strength that achieves the maximum transmittance varies depending on the liquid crystal material, the electrode spacing is set according to the liquid crystal material, and within the range of the maximum amplitude of the signal voltage set by the withstand voltage of the video signal driving circuit (signal side driver) used. , So that the maximum transmittance can be obtained. When a liquid crystal material described later is used, the electrode interval is 16 μm.

Further, in this embodiment, all the electrodes are arranged on the TFT substrate side. In particular, the counter electrode CT and the counter voltage signal line CL may be on the counter substrate side, which is also the present invention. It is included in the category.

<Cross-Sectional Structure of Matrix (Pixel)> FIG. 11 is a cross-sectional view taken along section line 3-3 in FIG. In this figure, a thin film transistor TF is provided on the lower substrate (upper transparent glass substrate) SUB1 side with respect to the liquid crystal layer LC.
T, a storage capacitor Cstg, and an electrode group are formed, and a color filter FIL and a light-shielding black matrix pattern BM are formed on the upper substrate (upper transparent glass substrate) SUB2 side.

On the outer surfaces of the upper and lower substrates SUB2 and SUB1, there are provided polarizing plates POL1 and POL2 having polarization axes arranged orthogonally (crossed Nicols arrangement).

<Counter Electrode CT> The counter electrode CT is formed of the conductive film g1 in the same layer as the gate electrode GT and the scanning signal line GL. Further, an anodic oxide film AOF of aluminum is also provided on the counter electrode CT. The counter electrode CT is configured to apply a counter voltage Vcom. In this embodiment, the counter voltage Vcom is a field generated when the thin film transistor element TFT is turned off from an intermediate DC potential between the minimum level drive voltage Vdmin and the maximum level drive voltage Vdmax applied to the video signal line DL. Although the potential is set to be lower by the through voltage ΔVs, if it is desired to reduce the power supply voltage of the integrated circuit used in the video signal driving circuit to about half, an AC voltage may be applied.

<Pixel Electrode PX> The pixel electrode PX is a second conductive film d of the same layer as the source electrode SD1 and the drain electrode SD2.
2, the third conductive film d3. Further, the pixel electrode PX is formed integrally with the source electrode SD1.

<Storage Capacitor Cstg> The pixel electrode PX is formed so as to overlap the counter voltage signal line CL at the end opposite to the end connected to the thin film transistor TFT. This superposition forms a storage capacitor (capacitance element) Cstg having the pixel electrode PX as one electrode PL2 and the counter voltage signal line CL as the other electrode PL1, as is apparent from FIG. The dielectric film of the storage capacitor Cstg includes an insulating film GI used as a gate insulating film of the thin film transistor TFT and an anodic oxide film AOF.

As shown in FIG. 10, the storage capacitor Cstg is formed in a portion where the width of the conductive film g1 of the counter voltage signal line CL is increased in plan view.

Next, a liquid crystal layer, an alignment film, a polarizing plate, and the like, which are features of the present invention, will be described.

<Liquid Crystal Layer> The liquid crystal material LC has a positive dielectric anisotropy Δε, a value of 13.2, and a relative dielectric constant ε‖ in a direction parallel to the optical axis of liquid crystal molecules of about 17.6. , The relative dielectric constant ε⊥ in the vertical direction is about 4.4, and the refractive index anisotropy Δn is about 0.4.
081 (value at 589 nm, 29 ° C), normal refractive index n ₀ is 1.465, extraordinary refractive index n _e is used a nematic liquid crystal of 1.546. The thickness of the liquid crystal layer is 3.9 μm, and the retardation Δn · d is 0.316 μm.
With this retardation Δn · d, the maximum contrast ratio can be obtained in the case of the initial alignment angle of the liquid crystal and the arrangement of the polarizing plate described later. The thickness of the liquid crystal layer is controlled by polymer beads (spacer beads).

Although the liquid crystal material LC is not particularly limited, the larger the value of the dielectric anisotropy Δε is, the more the driving voltage can be reduced, and the elastic constant K2 related to rotation is smaller. As the value is smaller, the driving voltage can be reduced.

<Alignment Film> In this embodiment, polyimide is used as the alignment film. Hereinafter, this alignment film will be described.

FIG. 1B shows the rubbing direction RDR of the alignment film.
, The transmission axis direction MAX of the polarizing plate, and the application direction ED of the electric field.
The relationship with R is shown.

The alignment film ORI1 on the lower substrate side is rubbed in the rubbing direction RDR1. Further, the alignment film OR2 on the upper substrate side is rubbed in the rubbing direction RDR2.

Here, the initial alignment state of each liquid crystal molecule is defined by the tilt direction and the initial alignment direction. In this embodiment, among the directions of the directors of the liquid crystal molecules, the direction perpendicular to the display surface of the liquid crystal layer is the tilt direction, and the direction of the in-plane component is the initial alignment direction.

The initial orientation angle φLC is defined as a counterclockwise direction with respect to the in-plane direction of the transverse electric field as a positive direction, and is defined at an angle of −90 degrees or more and 90 degrees or less. That is, in either the rubbing direction RDR or the reverse direction, a direction in a range of −90 degrees or more and 90 degrees or less with respect to the in-plane direction of the horizontal electric field is set as the initial alignment direction. Alignment film ORI1 on lower substrate side
The liquid crystal molecules on the surface have an initial alignment angle φLC1, and
Liquid crystal molecules on the surface of the alignment film ORI2 on the upper substrate side have an initial alignment angle φLC2.

In the first embodiment, the rubbing directions RDR1, RDR
DR2 is set to the same direction RDR (parallel rubbing), and the angle made with the applied voltage direction EDR is set to 75 degrees. Therefore, the orientation of the tilt angle of the liquid crystal molecules in the liquid crystal layer on the upper and lower substrate sea surfaces is in a splay state, and the liquid crystal molecules have an effect of compensating the optical characteristics with each other, thereby obtaining a wide viewing angle characteristic.

However, the rubbing directions RDR1 and RD1 are set so that the tilt angles of the liquid crystal molecules in the liquid crystal layer become parallel.
Even when R2 is set in the opposite direction (antiparallel rubbing), it is known that a wide viewing angle characteristic can be obtained if the pretilt angle is 10 degrees or less.

The initial orientation angle φLC1 = φLC2 = φLC is 75 degrees. That is, in the state where no electric field is applied, almost all liquid crystal molecules have a constant initial alignment angle φLC of 75 degrees,
It is in a homogeneous alignment state that is parallel to the substrate surface and has no twist.

As the polarizing plate POL, G1 manufactured by Nitto Denko Corporation
Polarizing plate POL on the lower substrate side using 220DU (trade name)
The first polarization transmission axis MAX1 is made to coincide with the rubbing direction EDR, and the polarization transmission axis MAX2 of the upper polarizing plate POL2 is orthogonal to the polarization transmission axis MAX2 of the lower polarizing plate POL1.
FIG. 1B shows the relationship.

As a result, the pixel electrode PX and the counter electrode CT
As the applied voltage increases during this period, the transmittance gradually increases to obtain a normally black characteristic that provides a bright display.

Further, the polarization transmission axis MAX2 of the upper polarizing plate POL2 and the polarization transmission axis MAX1 of the lower polarizing plate POL1.
The same characteristics can be obtained even if the above relationships are interchanged.

<Spacer> In the liquid crystal manufacturing process, the lower substrate S
After cleaning the UB1 and the upper substrate SUB2, a polyimide-based alignment film is applied and baked on each substrate, and the surfaces thereof are subjected to a rubbing treatment. Then, polymer beads (spacer beads) having a diameter of about 4 μm whose surface has been subjected to an orientation treatment are sprayed on the display section so that the spray density becomes about 200 / mm ^2, and an adhesive as a sealant is applied to the periphery to apply the adhesive. The substrates are bonded together and the adhesive is cured. Thereafter, a liquid crystal having a positive dielectric anisotropy and a refractive index anisotropy of about 0.081 is sealed.

In Example 1, spacer beads were obtained by treating the surface of polymer beads SP2040 (trade name) manufactured by Sekisui Fine Chemical Co., Ltd. with dodecyltrimethylammonium chloride and modifying the surface to have a vertical orientation. In addition, as a surface treatment method, there is a method using a material treated with an organic silane-based treating agent such as dodecyltriethylammonium chloride or dodecyltriethyloxysilane. Alternatively, JP-A-7-3
Among the polymers described on page 3, left column, lines 14 to 50 of JP 33623, a polymer which is polymerized on the surface in the presence of a monomer A having a hydrolyzable silyl group and a mercapto group is used. As the monomer B, there is a method using polymer beads having a long-chain alkyl group, for example, stearyl acrylate, lauryl methacrylate, or the like.

The polymer beads used as spacer beads have a relative dielectric constant of 2.9 and the polymer beads have a refractive index of 1.57.

<Equivalent Circuit of Entire Liquid Crystal Display> FIG. 12 is a connection diagram of an equivalent circuit of a display matrix unit and its peripheral circuits. This figure is a circuit diagram, but is drawn corresponding to an actual geometric arrangement. AR is a matrix array in which a plurality of pixels are two-dimensionally arranged.

In the drawing, X represents a video signal line DL, and suffixes G, B, and R are added corresponding to green, blue, and red pixels, respectively. Y represents the scanning signal line GL, and the suffixes 1, 2, 3,..., End are added according to the order of the scanning timing.

The scanning signal line Y (subscript omitted) is connected to the vertical scanning circuit V, and the video signal line X (subscript omitted) is connected to the video signal driving circuit H.

SUP is a power supply circuit for obtaining a plurality of stabilized voltage sources divided from one voltage source or a CRT from a host (upper processing unit: host computer).
This is a circuit including a circuit for converting display information for a (cathode ray tube) into information for a TFT liquid crystal display device.

<Overall Configuration of Liquid Crystal Display Module> FIG.
FIG. 2 is an exploded perspective view showing each component of a liquid crystal display module MDL in which a liquid crystal display device is integrated as a display device.

In FIG. 13, SHD is a frame-shaped shield case (also referred to as a metal frame) made of a metal plate.
CW is a display window, PNL is a liquid crystal display panel, SPB is a light diffusion plate, LCB is a light guide, RM is a reflection plate, BL is a backlight fluorescent tube, LCA is a backlight case,
The respective members are stacked in a vertical arrangement as shown in the drawing to assemble the liquid crystal display module MDL.

The module MDL is a shield case SH
The entirety is fixed by the claws provided on D and the hooks formed on the backlight case LCA.

The backlight case LCA is configured to house the backlight fluorescent tube BL, the light diffusion plate SPB, the light guide LCB, and the reflection plate RM. The backlight case LCA is disposed on the side of the light guide LCB. The liquid crystal display panel PN is used to illuminate the light from the tube BL with the light guide LCB, the reflection plate RM, and the light diffusion plate SPB so that illumination light having a uniform distribution is obtained on the display surface.
Light is emitted in the L direction.

The inverter circuit board PCB3 connected to the backlight fluorescent tube BL is connected to the backlight fluorescent tube B.
L is a power supply for driving L.

<Characteristics of Liquid Crystal Display Device of First Embodiment> In the liquid crystal display device of the first embodiment, light leakage around the spacer beads BZ during dark display is as shown in FIG. The four light leakage portions LK as described above can be observed, and the range of the light leakage is limited to a range within at most twice the radius from the center of the bead. Therefore, FIG.
8, a transmittance T-applied voltage Vs curve shown by a curve 31 is obtained, and the display contrast is about 120, and a sufficient contrast is obtained. It should be noted that the applied voltage Vs is
This is an effective voltage applied between X and the counter electrode CT.

Further, there is also an effect that it does not change even when a vibration or impact within the usage rule is given. Furthermore, a change in brightness when the viewing angle direction was changed was small, and a liquid crystal display device with greatly improved viewing angle characteristics was obtained.

Next, in order to clarify the effects of the present invention,
A comparative example is shown.

<Comparative Example 1> A liquid crystal display device similar to that of Example 1 was manufactured except that polymer beads SP2040 (trade name) manufactured by Sekisui Fine Chemical Co., Ltd. without surface treatment were used as spacer beads.

Light leakage from the periphery of the spacer beads during dark display is as shown in FIG.
The range of the light leakage LK of the spherical type covering the entire periphery of Z is the maximum range, and may extend up to four times the radius from the center of the spacer bead.
In some cases, it expanded over the gap between T.

That is, FIG. 16A is a plan view schematically showing an alignment state of liquid crystal molecules near the center of the liquid crystal layer around the spacer beads where no alignment treatment is performed when no electric field is applied. FIGS. 17A and 17B show the alignment films ORI 1 and ORI 1 along the AA ′ cutting line and the BB ′ cutting line in FIG. 16A.
It is sectional drawing which shows typically the orientation state of the liquid crystal molecule between ORI2.

As shown in FIGS. 17A and 17B, in the section in the rubbing direction RDR, the liquid crystal molecules in the vicinity of the spacer bead are in a random direction from the spacer bead surface in the portion near the alignment film surface. The alignment regulating force acts, and the portion where the alignment state is disturbed extends over a wide range.

Therefore, as shown in FIG.
When no electric field EDR is applied, the initial alignment direction of liquid crystal molecules near the center of the liquid crystal layer on the surface of the spacer beads is considered to be arranged in a random direction when viewed in a plan view.

Therefore, a transmittance T-applied voltage Vs curve shown by a curve 30 in FIG. 18 is obtained, and the display contrast is 7
The contrast becomes 0 to 50 or less, and the contrast becomes practically insufficient.

<Comparative Example 2> Polymer spacer SP2 manufactured by Sekisui Fine Chemical Co. without surface treatment as a spacer
A liquid crystal display device similar to that of Example 1 was produced except that 040 (trade name) was used. However, the light leakage LK portion is composed of two crescent-shaped types covering the rubbing direction RDR. In particular, in the case of two crescent-shaped types, the dark display portion between each crescent-shaped pattern shifts from the rubbing direction. A tendency for the area of light leakage to increase was observed.

FIG. 16B is a plan view schematically showing an alignment state of liquid crystal molecules near the center of the liquid crystal layer around the spacer beads when no voltage is applied, which causes crescent-shaped light leakage.

As shown in FIG. 16 (b), it is considered that some alignment regulating force exists near the bead surface even without performing the alignment treatment. For example, it is assumed that the mode 1 horizontal alignment regulating force exists. doing. However, the range of these two crescent-shaped light leaks is not as wide as the spherical light leak, but the display contrast is 70 or less, which is insufficient for practical use.

Example 2 As a spacer, polymer beads SP2040 (trade name) manufactured by Sekisui Fine Chemical Co., Ltd. were dipped in a polyimide alignment film solution, pulled up, baked in a thermostat at 180 ° C. for 1 hour, and subjected to horizontal alignment treatment. A liquid crystal display device similar to that of Example 1 was manufactured except that beads were used.

Light leakage from around the spacer during dark display is as follows.
As shown in FIG. 4A or FIG. 6A, a transmittance T-applied voltage Vs curve shown by a curve 31 in FIG. 18 was obtained, and the display contrast was increased to 150.

In the case of the horizontal alignment processing, it is considered that a composite mode of the mode 1 and the mode 2 also exists, but the light leakage region tends to be further reduced as compared with the case of the vertical alignment processing. In addition, the effect of no change even when vibration is applied was obtained.

In addition, in addition to the above, the orientation treatment of the spacer beads may be performed by adding hydrophilic functional groups such as -OH, -O
A horizontal alignment treatment that can emit CH ₃ , —COCH ₃ , —COOH, and the like to the surface can be applied.

The relative permittivity of the polymer beads used as the spacer is preferably 4.4 or less, the relative permittivity of the polymer beads used in Example 2 is 2.9, and the relative permittivity of the liquid crystal composition is 2.9. ε と し た and relative permittivity ε⊥.

In the horizontal electric field method, when the relative dielectric constant of the liquid crystal composition is smaller than the relative dielectric constant of the spacer beads, the lines of electric force become rough inside the spacer beads, and the electric field EDR generated between the electrodes is reduced around the spacer beads. Bend along. This electric field acts to orient the liquid crystal molecules parallel to the surface of the spacer beads, so that the vertical alignment spacer beads disturb the liquid crystal alignment on the spacer bead surface, but the parallel alignment spacer beads suppress the peripheral alignment disturbance. effective. Therefore, in the horizontal electric field method, it is considered that the stability of the alignment of the liquid crystal around the spacer beads in the driving state is higher in the spacer beads in the parallel orientation than in the spacer beads in the vertical orientation.

Further, the refractive index of the polymer beads used as the spacer beads is 1.57, which is close to the normal light refractive index and the extraordinary light refractive index of the liquid crystal composition. Can be.

[Embodiment 3] FIG. 8 (a) shows a liquid crystal display device manufactured by using spacer beads having a weak alignment control force by performing the same vertical alignment treatment as in Embodiment 1 but shortening the alignment treatment time. At 50G (450m / sec
² ) Changes in the four light leak portions when the above strong impact is applied are shown.

When the angle between the rubbing direction RDR and the direction connecting the center of the spacer bead BZ with the rubbing direction RDR near the rubbing direction at the four places where there is almost no light leakage is φF, then φF becomes As you grow up,
It was found that the area of light leakage increased, and when the angle became 45 degrees or more, the shapes almost coincided with the two crescent-shaped types shown in Comparative Example 2 described above, and the display contrast was reduced to 70 or less. Therefore, non-defective products were selected so that the angle φF was 45 degrees or less, and preferably 30 degrees or less, and a display contrast of 100 or more was obtained.

Further, although not shown, in the case where the horizontal alignment regulating force or the vertical alignment regulating force on the surface of the spacer beads is weak, a strong vibration or impact may give a light leakage area. That is, normally, when there is almost no light leakage in four places, when a strong vibration or impact is applied, the transmittance in the black state partially changes, and the light changes into two crescent-shaped light leaks, and the display area is specified. And white unevenness with large light leakage was observed in the portion.

That is, it was found that if the alignment regulating force on the surface of the spacer beads was too weak, a display defect would occur due to vibration or impact.

Example 4 The polarization transmission axis MAX1 of the polarizing plate POL1 on the lower substrate side was made to coincide with the rubbing direction RDR.
The polarization transmission axis MAX2 of the polarizing plate POL2 on the upper substrate side is arranged parallel to the polarization transmission axis MAX1 of the polarizing plate POL1 on the lower substrate side, and normally displays bright when a low voltage VL is applied and dark when applied with a high voltage. A liquid crystal display device similar to that of Examples 1 and 2 was produced except that the liquid crystal display device had white characteristics.

Thus, the pixel electrode PX and the counter electrode CT
As the applied voltage increases during this period, the transmittance gradually decreases and a normally white characteristic in which a dark display state is achieved can be obtained.

FIG. 18 shows a difference between the optical characteristic 33 when the spacer beads subjected to the orientation treatment are used and the optical characteristic 32 when the spacer beads without the orientation treatment are used.

In the case of the normally white characteristic, the low voltage V
Since the display becomes bright when L is applied, the effect of the dark display portion around the spacer beads can be neglected. However, when the dark display occurs when the high voltage VH is applied, if the alignment state is disturbed, the display contrast is reduced.

That is, in the spacer beads which are not subjected to the alignment treatment, even when an electric field is applied, as shown in FIG. 17, the range in which the alignment state is disturbed is wider, so that the black level is not sufficiently reduced.

[Embodiment 5] Embodiments 1 to 4 have described the case where display is performed in a birefringence mode with homogeneously aligned liquid crystal molecules having almost no twist.

However, in the initial alignment state, the rubbing direction R
DR1 and RDR2 are shifted by 90 degrees on the vertical alignment film side,
Even in the case of displaying in the birefringence mode with the liquid crystal molecules having a homogeneous initial alignment that has been twisted, the display contrast is improved by using the spacer beads that have been subjected to the alignment treatment.

In this case, the shape of the light leakage LK from the beads BZ was a spherical type light leakage shape both when no voltage was applied and when a voltage was applied. Can be suppressed within twice the radius, and the display contrast becomes 100 or more.

Although the present invention has been described with reference to the structures of the first to sixth embodiments, the present invention is not limited to these embodiments. For example, a horizontal electric field system is used to display not only the birefringence mode but also the optical rotation mode. The present invention is similarly applicable to the case, and is included in the scope of the present invention.

[0145]

As described above, according to the present invention,
By using beads whose surfaces have been subjected to appropriate alignment treatment as spacers, the orientation change region around the spacer beads can be reduced, and light leakage is small, and a stable high-contrast horizontal electric field type liquid crystal display device is provided. Obtainable.

Further, since the liquid crystal alignment on the surface of the spacer beads is stabilized, even if vibration or shock is applied to the liquid crystal display device during transportation or the like, even if the liquid crystal moves at a portion where the amplitude of the vibration or shock is large, the liquid crystal moves. The orientation around the spacer beads does not change, and light leakage does not increase.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a state of light leakage from around a spacer bead during dark display in a liquid crystal display device according to the present invention, a rubbing direction of an alignment film, a transmission axis direction of a polarizing plate, and an electric field application direction.

FIG. 2 is a plan view schematically showing an alignment state of liquid crystal molecules in a central portion of a liquid crystal layer around a vertical alignment spacer bead when no electric field is applied and when an electric field is applied in a liquid crystal display device according to the present invention.

FIG. 3 is a cross-sectional view schematically showing an alignment state between alignment films along an AA ′ cutting line and a BB ′ cutting line in FIG. 2;

FIG. 4 is a plan view schematically showing an alignment state of liquid crystal molecules near a center of a liquid crystal layer around a horizontal alignment spacer bead in mode 1 when an electric field is not applied and when an electric field is applied in the liquid crystal display device according to the present invention.

5 is a cross-sectional view schematically showing an alignment state of liquid crystal molecules between alignment films along an AA ′ cutting line and a BB ′ cutting line in FIG.

FIG. 6 is a plan view schematically showing an alignment state of liquid crystal molecules near the center of a liquid crystal layer around a horizontal alignment spacer bead in mode 2 when no electric field is applied and when an electric field is applied in the liquid crystal display device according to the present invention.

FIG. 7 is a cross-sectional view schematically showing an alignment state of liquid crystal molecules between alignment films along an AA 'cutting line and a BB' cutting line in FIG.

FIG. 8 shows a case where a strong shock was applied to a liquid crystal display device manufactured using spacer beads having a weak alignment regulating force.
It is a top view which shows the mode of a change of the light leakage part of a location.

FIG. 9 is an explanatory diagram of the operation principle of the in-plane switching mode liquid crystal display device according to the present invention.

FIG. 10 is a plan view illustrating one pixel of a liquid crystal display device according to the present invention and its periphery.

FIG. 11 is a sectional view taken along section line 3-3 in FIG. 10;

FIG. 12 is a connection diagram of an equivalent circuit of a display matrix portion of a liquid crystal display device according to the present invention and peripheral circuits thereof.

FIG. 13 is an exploded perspective view illustrating each component of a liquid crystal display module in which the liquid crystal display device according to the present invention is assembled as a display device.

FIG. 14 is a plan view illustrating an example of light leakage around a spherical spacer bead when no electric field is applied in a conventional in-plane switching mode liquid crystal display device.

FIG. 15 is a plan view showing an example of a portion of light leakage from around a spacer bead in a rubbing direction at the time of dark display when using spacer beads without alignment treatment observed in a conventional liquid crystal display device.

FIG. 16 is a plan view schematically showing an alignment state of liquid crystal molecules near the center of a liquid crystal layer around beads where no alignment treatment is performed when no electric field is applied.

17 is a cross-sectional view schematically illustrating an alignment state of liquid crystal molecules between alignment films along an AA ′ cutting line and a BB ′ cutting line in FIG. 16;

FIG. 18 is a characteristic curve diagram of equivalent ratio-applied voltage showing a difference between optical characteristics when using a spacer subjected to orientation treatment and optical characteristics when using a spacer without orientation treatment.

[Explanation of symbols]

 BZ Spacer beads LZ Light leakage from around spacer beads during dark display RDR Rubbing direction of alignment film MAX Transmission axis direction of polarizer EDR Electric field application direction PX Pixel electrode CT Counter electrode.

Continued on the front page (72) Inventor Shigeru Matsuyama 3300 Hayano, Mobara-shi, Chiba Pref. Electronic Device Division, Hitachi, Ltd.

Claims (6)

[Claims] 1. A pair of insulating substrates, at least one of which is transparent, a pair of alignment films formed between the pair of insulating substrates, a spacer and a liquid crystal composition sandwiched between the pair of alignment films. In a liquid crystal display device having a pixel electrode and a counter electrode for applying an electric field having an electric field component substantially parallel to the substrate surface, and at least one polarizing plate, the spacer is subjected to a vertical alignment process or a horizontal alignment process. A liquid crystal display device characterized by the above-mentioned. 2. A pair of insulated substrates, at least one of which is transparent, a pair of alignment films which are rubbed between the pair of substrates in a substantially parallel direction or a substantially antiparallel direction, and the pair of alignment films. In a liquid crystal display device having a spacer and a liquid crystal composition sandwiched between films, a pixel electrode and a counter electrode for applying a horizontal electric field substantially parallel to the substrate surface, and a pair of polarizing plates sandwiching the pair of substrates. When the liquid crystal display device is observed from a direction perpendicular to the display surface in a state where the electric field is not applied, an angle φF formed between the direction of the portion near the spacer where there is substantially no light leakage and the initial alignment method by the rubbing process. A liquid crystal display device characterized in that the surface of the spacer is subjected to an alignment treatment so as to be within zero degrees or ± 45 degrees. 3. A pair of opposed insulating substrates, at least one of which is transparent; a pair of alignment films rubbed between the pair of substrates in a substantially parallel direction or a substantially antiparallel direction; In a liquid crystal display device having a spacer and a liquid crystal composition sandwiched between films, a pixel electrode and a counter electrode for applying a horizontal electric field substantially parallel to the substrate surface, and a pair of polarizing plates sandwiching the pair of substrates. A liquid crystal display device, wherein the surface of the spacer is subjected to an alignment treatment such that light leakage near the spacer is reduced to four or four or more positions in a state where the electric field is not applied. 4. The liquid crystal display device according to claim 1, wherein spherical spacers are used as said spacers. 5. The liquid crystal display device according to claim 1, wherein said liquid crystal composition has a positive dielectric anisotropy. 6. The liquid crystal display device according to claim 2, wherein the light transmission axes of said pair of polarizing plates form an angle of 90 ° or 90 ± 10 ° with each other, and the light of the upper or lower polarizing plate is formed. A liquid crystal display device, wherein a transmission axis coincides with an upper or lower rubbing direction.