JPH11212095A - Liquid crystal display device and production therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the threshold voltage reduction of a lateral electric field system and the shortening of response time by providing an opening part transmitting light and a non-opening part transmitting no light inside one pixel, and making the alignment direction of a liquid crystal layer in a state of applying no voltage different for the opening part and non-opening part. SOLUTION: This device is provided with a pair of substrates 7 of which one substrate is transparent, liquid crystal layer arranged between a pair of substrates 7, and electrode groups (1, 3 and 4) formed on one of a pair of substrates 7 so as to apply electric fields parallel to the surface of the substrate to liquid crystal. Besides, this device is provided with plural active elements connected to these electrode groups, alignment layer 5 arranged between the liquid crystal and the substrate, and optical means for changing optical characteristics corresponding to the orienting state of the liquid crystal layer, and the opening part transmitting light and the non-opening part transmitting no light are provided inside one pixel. While using a light orienting organic polymer for the alignment layer 5, an alignment direction 15 of liquid crystal at the non-opening part when applying no voltage is made different from an alignment direction 16 of liquid crystal at the opening.

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 which has good visibility in oblique directions and is suitable as a stationary large screen monitor, and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the spread of OA equipment, there is an increasing need to save office space and improve the OA working environment. In addition, the ratio of OA equipment to power consumption is steadily increasing, and energy saving of individual OA equipment is also an important issue. A liquid crystal display device characterized by thinness, light weight and low power consumption is the only liquid crystal display device that can satisfy these requirements.

A viewing angle characteristic of a liquid crystal display device using polarized light is as follows.
It is determined by the alignment state of the liquid crystal layer. When the average orientation direction of the liquid crystal layer is in the plane direction of the substrate, the viewing angle characteristics are good. In most liquid crystal display devices before the horizontal electric field method, the above condition was satisfied only in one of the dark display and the bright display, so that their viewing angle characteristics were insufficient for a stationary large-screen monitor. Was.

The in-plane switching mode liquid crystal display device has sufficient display characteristics for use as a monitor because the average orientation direction of the liquid crystal layer is in the direction of the substrate plane in both dark display and bright display. In order to realize this, in the lateral electric field method, a comb-shaped electrode is provided on one side of a pair of substrates, and the direction of the electric field applied to the liquid crystal layer is directed to the plane direction of the substrate.

[0005] The threshold voltage and response time of a liquid crystal display device are determined by factors such as the viscosity coefficient, elastic modulus, dielectric anisotropy, and electric field intensity applied to the liquid crystal layer.

In the horizontal electric field method, the contribution of the above-mentioned factors to the threshold voltage and the response time also greatly changes because the structure of the electrodes is changed. As a result, both the threshold voltage and the response time are increased as compared with an active matrix liquid crystal display device that does not use a comb-shaped electrode. Specifically, the threshold voltage is about 6 V or more,
The response time was about 90 ms or more.

[0007]

As described above, the threshold voltage and the response time are affected by the viscosity coefficient, elastic coefficient, and dielectric anisotropy of the liquid crystal material. Therefore, a method for improving the threshold voltage and the response time by improving the physical properties of the liquid crystal material is considered first.

However, since the physical property values of the liquid crystal material are in a trade-off relationship with each other, it seems difficult to change all the physical property values so as to improve the threshold voltage and the response time. Therefore, it is not expected that the improvement of the physical properties of the liquid crystal material significantly improves the threshold voltage and the response time.

Reduction of the threshold voltage is necessary for reducing the cost of the driving system. In addition, shortening of the response time is necessary for reproducing a fast-moving moving image.

An object of the present invention is to reduce the threshold voltage and the response time of the in-plane switching method.

[0011]

In the present invention, attention has been paid to the alignment state of the liquid crystal layer. We thought that if the orientation of the liquid crystal layer was changed, the contribution of the viscoelastic coefficient to the threshold voltage and the response time could be changed even if the liquid crystal material was the same.

In one pixel of the liquid crystal display device, a signal electrode,
Opaque members such as a common electrode, a pixel electrode, and a black matrix are distributed, and there are portions that do not transmit light. In addition, there is a portion through which light passes without these opaque members.

The former is referred to as a non-opening, and the latter is referred to as an opening. In addition, a part of the non-opening means, for example, a portion where an opaque electrode formed of a metal such as a signal electrode, a common electrode, or a pixel electrode in the non-opening is distributed, or a portion where these metal electrodes are distributed. Also refers to a part of In the present invention, a part of the non-opening is generally referred to as a non-opening.

The gist of the present invention for solving the above problems is as follows.

[1] At least one of a pair of transparent substrates, a liquid crystal layer disposed between the pair of substrates, and an electric field formed on one of the pair of substrates and parallel to the substrate surface. An electrode group for applying to the liquid crystal, a plurality of active elements connected to these electrode groups, an alignment layer disposed between the liquid crystal and the substrate, and an optical characteristic according to an alignment state of the liquid crystal layer. The liquid crystal display device of the active matrix type having an optical means for changing the aperture, and having an opening for transmitting light and a non-opening for not transmitting light in one pixel, the orientation direction of the liquid crystal layer in a state where no voltage is applied. The liquid crystal display device differs between the opening and the non-opening.

[2] The alignment layer is close to the liquid crystal layer,
In the above-mentioned liquid crystal display device, when the alignment direction of the liquid crystal at the interface between the alignment layer and the liquid crystal layer is defined as the interface alignment direction, the interface alignment direction is different between the opening and the non-opening.

[3] The liquid crystal display according to the above, wherein the alignment layer is formed of a photoreactive organic polymer film.

[4] In the above liquid crystal display device, the angle formed between the interface orientation direction and the electric field direction is larger in the opening than in the non-opening.

[5] In the above liquid crystal display device, the angle between the interface orientation direction and the electric field direction in the opening is 45 to 85 degrees.

[6] Assuming that the alignment direction of the liquid crystal at the interface between the alignment layer and the liquid crystal layer is the interface alignment direction, the method of manufacturing the liquid crystal display device, wherein the interface alignment direction differs between the opening and the non-opening, The alignment layer is formed of a photo-polymerization type photo-alignment material, and is selectively photopolymerized and aligned by irradiating linearly polarized light at a predetermined angle while shielding the opening (or non-opening), Next, the non-opening (or the opening) is irradiated with linearly polarized light at a predetermined angle to be photopolymerized and oriented, and the orientations of the opening and the non-opening are different from each other at a predetermined angle. It is in the manufacturing method of the liquid crystal display device.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Among the alignment states of a liquid crystal layer, the alignment state of an opening has already been optimized in order to maximize display characteristics such as contrast ratio. Therefore, the alignment state of the liquid crystal layer in the non-opening part is changed while the alignment state of the opening part is kept as it is.

An example will be described with reference to FIGS. FIG. 1 shows a liquid crystal display device according to the present invention, and FIG. 2 shows a part of one pixel of a conventional lateral electrolysis type liquid crystal display device. FIGS. 1 and 2 show (a) and (c) liquid crystals when no voltage is applied. FIGS. 4B and 4D show the alignment state and the liquid crystal alignment state when a voltage is applied.

In the conventional liquid crystal display device of the horizontal electrolysis type shown in FIG. 2, as shown in FIGS.
1 and the alignment direction 22 of the liquid crystal 12 in the opening.
Are in the same direction.

On the other hand, in the liquid crystal display device of the present invention shown in FIG. 1, as shown in FIGS. 1A and 1C, the alignment direction 21 of the liquid crystal 15 in the non-opening portion and the alignment direction of the liquid crystal 16 in the opening portion. Direction 2
2 and the direction is different.

The opening and the non-opening having the same orientation as the opening are shown in white. A portion where the signal wiring, the common electrode, and the source electrode are present is a non-opening portion, which is indicated by oblique lines. The angle formed by the liquid crystal alignment direction 21 in the hatched portion and the electric field direction 9 is smaller than that in the liquid crystal alignment direction 22 in the white portion.

Next, a method for realizing the liquid crystal alignment as shown in FIG. 1 will be described. In order to make the liquid crystal alignment directions of the non-opening and the opening different, in the present invention, a photo-alignable polymer is used for the alignment film.

A liquid crystal display device using a photo-alignable polymer is:
For example, it is described in Japanese Patent No. 2608661. The photo-alignment polymer forms a chemical bond in the direction defined by the direction of electric vector oscillation of the linearly polarized light irradiated due to its photoreactivity, and the liquid crystal molecule is defined by the direction of the chemical bond in the photo-alignment polymer. Orientation. Therefore, the alignment direction of the liquid crystal by the photo-alignable polymer can be controlled by the direction of the electric vector oscillation of the linearly polarized light to be irradiated.

As shown in FIG. 4, the non-opening portion and other portions are sequentially masked and irradiated with light [FIG.
(B), (d)], the liquid crystal alignment directions of the non-opening and the opening may be different.

If light irradiation is sufficiently performed to complete the photoreaction of the photoalignable polymer, the photoalignable polymer does not react to subsequent light irradiation. Therefore, as shown in FIG. 5, if the photoreaction of the light irradiation part is completed by the first light irradiation [FIG.
(B)] In the second light irradiation, a mask is unnecessary [FIG. 5 (d)].

Since the non-opening where the signal wiring, the common electrode and the pixel electrode are present is opaque and the other parts are transparent, the opaque part in the non-opening may be used as a mask.

As shown in FIG. 6, first, light is irradiated from the back surface of the substrate (the side opposite to the surface on which the electrodes and the like are formed) to determine the orientation of the liquid crystal in the transparent portion including the opening. 6
(B)]. Next, light is irradiated from the substrate surface (the side on which the electrodes and the like are formed) to determine the alignment direction of the liquid crystal in the opaque portion in the non-opening (FIG. 6D).

The principle of operation of the in-plane switching method, which is the premise of the present invention, will be described with reference to the conventional example shown in FIG. FIG. 2 (a), (b)
FIGS. 2C and 2D are schematic cross-sectional views showing the operation of liquid crystal molecules in one pixel of a horizontal electric field method, and FIGS. 2C and 2D are front views. FIGS. 2A and 2C show the alignment state of the liquid crystal when no voltage is applied, and FIGS. 2B and 2D show the liquid crystal alignment state when the voltage is applied. Linear electrodes 1 and 4 are formed inside one of the substrates, and the surface of the substrate in contact with the liquid crystal layer is covered with an alignment film 5.

Due to the interaction with the alignment film 5, the rod-like liquid crystal molecules 11 and 12 are aligned at a slight angle in the longitudinal direction of the electrodes 1 and 4 at the interface between both substrates. When no voltage is applied, the alignment state of the liquid crystal in one pixel is substantially uniform, and has the above-described alignment.

Here, when different potentials are applied to the pixel electrode 4 and the common electrode 1 and an electric field 9 is applied to the liquid crystal due to the potential difference between the two, the dielectric anisotropy of the liquid crystal molecules causes the dielectric anisotropy shown in FIG.
As shown in (b) and (d), the liquid crystal molecules 12
Turn around. Accordingly, the light transmittance of the liquid crystal cell determined by the orientation direction of the liquid crystal and the azimuth of the transmission axis of the polarizing plate changes. The horizontal electric field method uses the change in light transmittance to perform display.

The response time of the liquid crystal display device corresponds to the time required for the liquid crystal layer to change the orientation when the applied voltage value is switched. This response time is defined as the time required for the transmittance change to reach 90% of the saturation value.

The change in the orientation of the liquid crystal layer due to the application of a voltage as described above is a Freedericksz transition. E. FIG. Jakeman
And E. P. PAYNS et al. (Literature: PHYSICS LE
According to TTERS Vol. 39A No. 1 pp69), the threshold voltage V _th of the Freedericksz transition, the response time T _on when the voltage is applied, and the response time T _off when the voltage is disconnected are represented by the following equations.

[0037]

[Number 1] _{V th = π√ (K / Δε} ) ... (1) T on = η / (ΔεE 2 / 4π-Kq 2) ... (2) T off = η / Kq 2 ... (3) here, K, η, Δε, and E are the effective value of the elastic modulus, the effective value of the viscosity coefficient, the dielectric anisotropy, and the electric field strength, respectively.

Since the liquid crystal layer has anisotropy, its viscosity coefficient and elastic coefficient are classified into several types. Taking the elastic modulus as an example, the elastic modulus of the nematic liquid crystal layer is k ₁₁ , k ₂₂ , k ₃₃
, And correspond to spray-type deformation, twist-type deformation, and bend-type deformation, respectively. Naturally, different types of viscosity coefficient and elastic coefficient have different values. Η and K in the above equations (1) to (3) are combinations of these several types of viscosity coefficient and elastic coefficient.

The combination of the viscosity coefficient and the elastic coefficient contributing to the Freedericks transition is determined by the manner in which the liquid crystal layer is deformed when a voltage is applied or cut off. Also, taking the elastic modulus as an example, the deformation of the liquid crystal layer in the case close to the spray-type deformation, the contribution of k ₁₁ becomes larger. Furthermore, if deformation close to the spray-type deformation to the liquid crystal layer in accordance with the voltage applied or a voltage cut occurs, the sign of which contributes k ₁₁ to become positive. Similarly, the sign of k ₁₁ if deformed close to the spray type is eliminated becomes negative.

The deformation that occurs in the liquid crystal layer due to the application of a voltage or the disconnection of the voltage is determined by the liquid crystal alignment state when no voltage is applied and the direction of the electric field. Of these, the direction of the electric field and the orientation of the opening are already optimized as described above.
The liquid crystal alignment state in the non-opening portion was changed.

The difference between the conventional in-plane switching method and the present invention will be described below. As shown in FIG. 2, in the conventional in-plane switching method, when no voltage is applied, both the liquid crystal alignment state of the opening and the liquid crystal alignment state of the non-opening part are equal to each other, forming about 75 degrees with respect to the direction of the electric field. When no voltage is applied, the liquid crystal layer is uniform and no deformation occurs.

As shown in FIG. 2B, in the thickness direction of the liquid crystal layer, twist-type deformation occurs with the application of a voltage, and as shown in FIG. Accordingly, the elastic coefficient K that contributes to the Freedericksz transition in the conventional in-plane switching method is expressed by the following equation (4).

[0043]

K = ak ₂₂ + bk ₁₁ + ck ₃₃ (4) where a, b, and c are positive coefficients.

On the other hand, in the present invention, as shown in FIG. 1, the alignment state of the liquid crystal in the non-opening portion when no voltage is applied is different from that in the opening portion. The former forms about 75 degrees with respect to the direction of the electric field as before, while the latter forms a smaller angle, for example, 15 degrees. Therefore, when no voltage is applied, a bend type and a spray type deformation occur in the direction of the electric field.

In this case, in the thickness direction of the liquid crystal layer, a twist-type deformation occurs in accordance with the voltage application as in the prior art [FIG.
(B)] In the direction of the electric field, the deformation of the bend type and the spray type is eliminated with the application of the voltage [FIG. 1 (d)]. Therefore, in the present invention, the elastic coefficient K that contributes to the Freedericksz transition is represented by the following equation (5).

[0046]

K = ak ₂₂ − (bk ₁₁ + ck ₃₃ ) (5) As is clear from the comparison between Expressions (4) and (5), K in the present invention is smaller than that in the conventional in-plane switching method. . Equation (1)
Than to (3), if the decrease in K is, V _th and T _on is reduced,
T _off increases. Therefore, in the present invention, the threshold voltage is reduced as compared with the conventional in-plane switching method, and driving at a lower voltage becomes possible.

In addition, the response time when applying a voltage is reduced, and the response time when disconnecting a voltage is increased. Low voltage driving is advantageous for reducing the cost of the driving system.

Next, the response time during low voltage driving will be described. FIG. 7 shows the dependency of the response time of the conventional in-plane switching method on the applied voltage by a broken line. T _on decreases with increasing applied voltage value, T _off is substantially constant regardless of the applied voltage value, both equal around 6V.

Attention will be paid to a low voltage region of 5 V or less, which is an applied voltage that can be stably obtained by a general-purpose LCD driving IC.

It is ideal if T _on and T _off are equal. However, in the conventional in-plane switching method, T _on is less than 5 V at 5 V or less.
More than twice larger than _off . When T _on and T _off are extremely different, the response time perceived by a human is determined by the longer of the two. For this reason, when the conventional in-plane switching method is driven at a low voltage, particularly intensely moving images tend to be slightly unclear.

FIG. 7 shows the dependence of the response time on the applied voltage according to the present invention.
Is shown by a solid line. T _on as of the in the present invention is reduced to T
_{Since off} increases, T _on and T _off during low voltage driving
Is reduced. As a result, a moving image can be clearly displayed even when driven at a low voltage of 5 V or less.

As described above, according to the present invention, it is possible to reduce the driving voltage of the in-plane switching method, which is characterized by a wide viewing angle, and to reduce the difference between the response times (T _on and T _off ) during low voltage driving. There is action.

[0053]

Next, the present invention will be described more specifically based on examples.

[Example 1] A thin film transistor 13 to which a lateral electric field can be applied and various wiring electrodes were formed on one of two transparent glass substrates polished on the surface with a thickness of 1.1 mm. An insulating protective film made of silicon was formed.

FIG. 3 shows the structure of the thin film transistor 13 and various wiring electrodes (scanning electrodes, signal electrodes). FIG.
A front view of one pixel and schematic cross-sectional views of AA ′ and BB ′ are also shown.

The thin film transistor element 13 is composed of the pixel electrode 4, the signal electrode 3, the scanning electrode 12, and the amorphous silicon 13. Further, the common electrode 1, the scanning electrode 12, the signal electrode 3, and the pixel electrode 4 were formed by patterning the same metal layer.

The pixel electrode 4 is formed between the three common electrodes 1 in the front view. The pixel pitch is 100 μm in the horizontal direction (between adjacent signal electrodes 3) and 300 μm in the vertical direction (between adjacent scan electrodes 12). The scanning electrode 12 and the signal electrode 3 extend over a plurality of pixels, and the electrode width is set wider to reduce the resistance and the line defect.

For the same reason, the electrode width of the wiring portion of the common electrode 1 (the portion formed at right angles to the signal electrode 3) was set to be wide. The widths of the scanning electrode 12, the signal electrode 3, and the common electrode 1 were 10 μm, 8 μm, and 8 μm, respectively.

On the other hand, in order to improve the aperture ratio, the width of the pixel electrode 4 and the portion of the common electrode 1 formed at right angles to the signal electrode 3 independently of each other are slightly reduced to 5 μm and 6 μm, respectively. And By reducing the width of the electrode, the possibility of disconnection due to foreign matter contamination etc. increases,
Even if a disconnection occurs in these electrodes, it is only a pixel defect, so that the influence is small.

The number of pixels was 640 × 3 × 480 with 640 × 3 signal electrode wirings and 480 scanning electrode wirings.

On the other substrate, a color filter with a black matrix was formed. The black matrix formed by combining the two substrates was formed outside the broken line 30 in FIG.

The non-opening portion in FIG. 3 refers to a portion inside the broken line 30 and where no metal electrode (the signal electrode 3, the common electrode 1, and the pixel electrode 4) is present. The opening refers to a portion outside the broken line 30 and inside the broken line 30 where the metal electrode exists.

As an alignment film on the two substrates, a polyvinyl ester having paramethoxycinnamic acid in a side chain was used. Its molecular structure is shown in Formula 1.

[0064]

Embedded image

(Where n is an integer) In the above formula, n is preferably from 50 to 100,000.

In this organic alignment film, the side chain paramethoxycinnamic acid causes a photodimerization reaction by light irradiation. If linearly polarized light is used as the irradiation light, a combination of two paramethoxycinnamic acids that cause a photoreaction in the vibration direction of the electric vector can be selected. That is, the direction of the chemical bond generated by the photoreaction can be controlled.

It is empirically known that the liquid crystal molecules are aligned in the direction perpendicular to the direction of oscillation of linearly polarized light. Therefore, the orientation of liquid crystal can be controlled by the direction of oscillation of irradiation light (linearly polarized light). If the photo process technology used for forming the thin film transistor is combined with this, a large number of minute regions having different alignment directions of the liquid crystal can be formed on the alignment film.

In addition to the organic alignment film represented by the formula [1], for example, an organic alignment film having a molecular structure represented by the formula [2] to [4] can be used in the same manner. Regarding these alignment films and optical alignment technology, for example, Japanese Patent No. 260
No. 8661 and Martin Schadt Hubert Seiber
le Andreas Schuster et al. (NATUREVo)
1.381, 16 May 1995).

Such organic compounds include:

[0070]

Embedded image

[Wherein, R is

[0072]

Embedded image

R ′ is — (CH ₂ ) _m — or — (CH ₂ ) _m —O
CO— and R ″ are —H, —F, —Cl, —CN, —OCH
₃ or _{- (CH 2) m H,} m is an organic compound represented by an integer from 1 to 10].

In the present invention, the alignment direction of the liquid crystal in the non-opening portion and the opening portion is set to be different by using the above-described photo-alignment material and the photo-alignment technique.

A high-pressure mercury lamp having a bright line at a wavelength of 320 nm was used as a light source, and natural light source light was linearly polarized through a Glan-Thompson prism. Irradiation light amount is 5J / c
It was m ^2.

FIG. 4 shows the alignment process of the alignment film. Of the two substrates, the above-mentioned organic alignment film 23 (thickness: 1000 °) is formed on the substrate (cross section AA ′ in FIG. 3) on which the thin film transistor 14 and various wiring electrodes are formed by spin coating.
Was formed [FIG. 4 (a)].

Next, a photomask 26 was formed on the substrate corresponding to the metal electrodes (1, 3, 4), and alignment was performed so that the light-shielding portion coincided with the metal electrode. Thereafter, linearly polarized light was irradiated from the photomask 26 side (FIG. 4B).

The direction of oscillation of the linearly polarized light was set to 15 degrees with respect to the direction of the electric field. In this manner, the metal electrodes (1,
An alignment treatment by light irradiation was selectively performed on portions other than the portions corresponding to (3, 4) to form an alignment treatment portion 24 on the alignment film 23 (FIG. 4C).

Next, a photomask 27 whose light-shielding portions correspond to portions other than the metal electrodes (1, 3, 4) is laminated, and the light-shielding portions are aligned so as to coincide with the above portions. Irradiated with linearly polarized light from the side [FIG. 4 (d)].

The oscillation direction of the linearly polarized light was set to be 75 degrees with respect to the direction of the electric field. In this manner, the metal electrodes (1,
The alignment treatment by light irradiation was selectively performed only on the portion where (3, 4) was distributed, and an alignment treatment part 25 was formed on the alignment film 23 (FIG. 4E).

An alignment treatment section was similarly formed on the other substrate. Note that the other substrate was formed such that the distribution of the alignment treatment portions of the alignment film was equal to that of the above substrate.

Next, the two substrates were assembled such that both alignment films faced each other. In order to make the liquid crystal layer thickness uniform over the entire display portion between the two substrates, a spacer was interposed between the two substrates. The spacer is a spherical polymer bead and is dispersed throughout the display unit. The periphery of the substrate was sealed with an epoxy resin mixed with spherical polymer beads and cured.

Through the above steps, the alignment directions of the liquid crystals on the two substrates were made substantially parallel to each other. The angle between the direction of the electric field and the orientation direction was 15 degrees for the metal electrode portion and 75 degrees for the other portions. That is, the direction is the vertical direction of the vibration direction of the irradiated linearly polarized light.

A nematic liquid crystal having a positive dielectric anisotropy of 10.2 (1 kHz, 20 ° C.) and a refractive index anisotropy of 0.075 (wavelength 590 nm, 20 ° C.) The composition was vacuum-injected, and the injection port was sealed with a UV-curable resin sealing agent. The thickness of the liquid crystal layer is 4.8 μm
And the retardation of the liquid crystal layer was 0.36 μm.

A polarizing plate (G1220DU, manufactured by Nitto Denko) was laminated on both sides of the liquid crystal cell, and one of the polarization transmission axes was parallel to the orientation direction of the opening, and the other was perpendicular to the opening. A normally closed electro-optical characteristic is obtained in which a dark display can be obtained at a low voltage and a bright display can be obtained at a high voltage by the alignment direction and electric field direction of the liquid crystal, the retardation of the liquid crystal layer, and the arrangement of the polarizing plate.

FIG. 8 shows the dependency of the transmittance on the applied voltage of the manufactured liquid crystal cell. A maximum value of 32.5% in transmittance was obtained at an applied voltage of about 4.7 V. Also, the applied voltage was changed from 0 V to 4.
The response time (T _on ) when switching to 7V is 44 ms,
Response time when switching from 4.7V to 0V (T _off )
Is 36 ms, and the above two response times are fairly close.

Next, a driving circuit was connected and a backlight was mounted to obtain a liquid crystal display device. When the display was driven under the condition that the effective value of the applied voltage in the bright display was 4.7 V, and various images including images with a sharp movement were displayed, and the display state was observed, the sharpness of the image with a sharp movement was also improved. Did not drop.

As described above, by setting the alignment direction of the liquid crystal to be different between the non-opening portion and the opening portion of the liquid crystal display device, a maximum value of transmittance can be obtained at a relatively low voltage (4.7 V). It was also found that the difference between T _on and T _off was small.
As a result, a liquid crystal display device capable of clearly displaying a rapidly moving image with low voltage driving was obtained.

[Embodiment 2] In the liquid crystal display device of Embodiment 1, the orientation direction of the portion where the metal electrodes are distributed is changed.
The angle between the direction of the electric field and the direction of orientation was 25 degrees. In this liquid crystal display device, the maximum value of the transmittance was obtained at 5.0 V, and the maximum value was 32.2%. Further, T _on and T _off were 50 ms and 31 ms, respectively.

The effective value of the applied voltage in bright display is 5.0
When driving was performed under the condition of V, and the display state was observed, the image was clear even when a rapidly moving image was displayed.

[Embodiment 3] In the liquid crystal display device of Embodiment 1, the orientation direction of the portion where the metal electrode is distributed is changed,
The angle between the electric field direction and the orientation direction was 35 degrees. In this liquid crystal display device, the maximum value of the transmittance was obtained at 5.4 V, and the maximum value was 32.4%. Further, T _on and T _off were 58 ms and 29 ms, respectively.

The effective value of the applied voltage in the bright display is 5.4.
When driving was performed under the condition of V, and the display state was observed, the image was clear even when a rapidly moving image was displayed.

[Embodiment 4] In the liquid crystal display device of Embodiment 1, the alignment treatment step of the alignment film was changed.

FIG. 5 shows the alignment process of the alignment film in this embodiment. First, similarly to the first embodiment, only the portion where the metal electrodes (1, 3, 4) are not distributed is selectively irradiated with light using the photomask 26 to perform alignment processing. Was formed [FIGS. 5 (b) and 5 (c)].

The oscillation direction of the linearly polarized light was set to 75 degrees with respect to the direction of the electric field as in the first embodiment. However, at this time, light irradiation was sufficiently performed to complete the photoreaction of the alignment processing unit 24, and then the photoreaction was prevented from occurring even when the light was irradiated.

Next, linearly polarized light was irradiated from the same direction as the first time without a photomask [FIG. 5 (d)]. The oscillation direction of the linearly polarized light was set to 15 degrees with respect to the direction of the electric field.

In this embodiment, the photoreaction of the light-irradiated portion is completed by the first light-irradiation, so that the second floor can be used only in the portion where the metal electrodes (1, 3, 4) are distributed without using a photomask. Could be selectively oriented [FIG.
(E)].

The display characteristics of the liquid crystal display device were as described in Example 1.
And the maximum value of the transmittance at 4.7 V (32.5 V).
%), And T _on and T _off are 44 ms and 35 ms, respectively.
Met. When a driving circuit was connected and the display state of the liquid crystal display device equipped with a backlight was observed, the image was clear even when a rapidly moving image was displayed.

[Embodiment 5] In the liquid crystal display device of Embodiment 1, the alignment process of the alignment film was changed. FIG. 6 shows an alignment process of the alignment film in this embodiment. First of all,
The substrate surface was irradiated with linearly polarized light from the side where the metal electrodes (1, 3, 4) were not formed [FIG.

At this time, since light does not pass through, it is possible to irradiate only a portion where these are not distributed. As described above, only the portion where the metal electrodes are not distributed is selectively subjected to the alignment treatment without using the photomask, and the alignment film 2 is provided on the alignment film 23.
4 was formed [FIG. At this time, the oscillation direction of the linearly polarized light was set at 75 degrees with respect to the direction of the electric field as in the first embodiment. Light irradiation was sufficiently performed in the same manner as in Example 4 to complete the light reaction, and thereafter, the light reaction was prevented from occurring even when the light was irradiated.

Next, the surface of the substrate on which the metal electrodes (1, 3, 4) were formed was irradiated with linearly polarized light without using a photomask [FIG. The oscillation direction of the linearly polarized light was set to 15 degrees with respect to the direction of the electric field. In this way,
A portion corresponding to the metal electrode portion which was not subjected to the orientation treatment by the first light irradiation without using the photomask was subjected to the orientation treatment to form the orientation-treated portion 23 (FIG. 9E).

The display characteristics of the liquid crystal display device thus produced are almost the same as those of the first embodiment, and the maximum value of the transmittance at 4.7 V (3
2.5%), and T _on and T _off are 44 ms, 3
It was 5 ms. When a driving circuit was connected, a backlight was mounted, and the display state was observed as a liquid crystal display device, the image was clear even when a rapidly moving image was displayed.

[Embodiment 6] In the liquid crystal display device of Embodiment 1, the boundary between two regions having different orientations was changed. In the liquid crystal display device according to the first embodiment, the boundary between the two regions having different orientations is matched with the boundary between the portion where the metal electrodes (1, 3, 4) are distributed and the other portion. The boundary was set within the distribution region of the metal electrode.

FIG. 9 shows a specific manufacturing process. FIG.
(A) to (e) correspond to FIGS. 4 (a) to (e).
The light shielding portion of the photomask 26 used for the first light irradiation is
This corresponds to the distribution region of the metal electrodes (1, 3, 4) on the substrate as in the first embodiment. However, the size of the distribution area is
The width was set to be narrower by about 2 μm than the distribution area of the metal electrodes.

This photomask was laminated on a substrate, arranged so that the light-shielding portion was positioned inside the metal electrode, and irradiated with linearly polarized light from the photomask side (FIG. 9B). The oscillation direction of the linearly polarized light was set to 15 degrees with respect to the direction of the electric field.
As described above, the inside of the metal electrodes (1, 3, 4) was selectively subjected to the orientation treatment to form the orientation-treated portion 24 [FIG.
(C)].

Next, the light shielding portion of the photomask used for the second light irradiation is complementary to the first photomask 26. The photomask 27 was stacked on the substrate, and the alignment was performed so that the light-shielding portion covered the entire opening and covered the non-opening irradiated with light in the first light irradiation. Next, linearly polarized light was applied from the photomask 27 side (FIG. 9D). The oscillation direction of the linearly polarized light was set to 75 degrees with respect to the direction of the electric field.

As described above, only the portion not irradiated with light in the first light irradiation was selectively subjected to the alignment treatment [FIG.
(E)].

The alignment film on the other substrate was also subjected to an alignment treatment in the same manner so that the distribution of the alignment treatment directions of the alignment films on both substrates was equal to each other. Thus, the boundary between the two regions having different orientations was set as the region inside the metal electrode.

In the liquid crystal display device of the present invention, polarizing plates are arranged above and below a liquid crystal cell. By arranging their transmission axes orthogonal to each other and making one of the transmission axes of the upper and lower polarizers coincide with the orientation direction of the liquid crystal, the light transmittance when no voltage is applied is reduced to 0%, and high. A contrast ratio is obtained. As described above, it is necessary to determine the orientation direction in the opening so as to coincide with one of the transmission axes of the upper and lower polarizing plates.

Since the orientation direction of the non-opening does not satisfy this condition, if the orientation of the non-opening is distributed in the opening, the dark display transmittance in that portion is not sufficiently reduced, and the contrast ratio Decrease.

In the alignment process shown in FIGS. 4, 5, 6, and 9, when the alignment accuracy of the photomask is reduced,
The boundary between the opening and the non-opening may be shifted from a predetermined position.

In the liquid crystal display device according to the first embodiment, when a shift occurs, the boundary also shifts and is located at the opening.
At this time, the liquid crystal alignment that should originally be distributed in the non-opening portion is distributed in the opening portion, so that the contrast ratio is reduced.

However, in this embodiment, since the boundary between the opening and the non-opening is set to the non-opening, it is possible to prevent a decrease in the contrast ratio even if the boundary deviates from a predetermined position to some extent.

In the above embodiments, the pixel electrode and the common electrode are made parallel and parallel to the signal wiring. However, other structures, for example, when the pixel electrode and the common electrode are not parallel, And one of the common electrodes
Even when not parallel to the signal wiring, it is possible to optimize the effective value of the viscoelastic constant, which contributes to the response time and threshold voltage, by making the liquid crystal alignment directions of the non-opening and the opening different. The same effect can be obtained.

In the present invention, a photo-polymerizable photo-alignment material is used for the liquid crystal alignment, but other photo-alignment techniques can be applied as long as the alignment direction of the liquid crystal after the alignment treatment can be fixed. Further, as long as the liquid crystal alignment directions of the non-opening portion and the opening portion are different from each other, an alignment technology other than the optical alignment technology can be applied.

Comparative Example 1 In the liquid crystal display device of Example 1, the orientation direction of the non-opening portion was changed, and the angle between the electric field direction and the orientation direction was set to 75 degrees. That is, the liquid crystal alignment directions of the opening and the non-opening were made the same as in the conventional in-plane switching method.

As a result, a maximum value of the transmittance appeared at 7.1 V, which was 32.6%. T _on and T _off were 73 ms and 25 ms, respectively.

The effective value of the applied voltage in the bright display is 7.1.
When the image was driven under the condition of V and the display state was observed, the outline of the image was blurred and the sharpness was lowered in an image with a sharp movement.

[0119] If the difference of T _on and T _off is large, the response characteristics of the liquid crystal display device which human beings feel corresponds to the larger of the T _{o n} and T _off. T _on and T _off each 73m
s, 25 ms, the response characteristic felt by humans is 73
ms.

[Comparative Example 2] The liquid crystal display device of Comparative Example 1 was driven under the condition that the effective value of the applied voltage in bright display was 4.7 V, as in Example 1. At this time, T _on and T _off were 95 ms and 21 ms, respectively. When the display state was observed, the brightness of the bright display was reduced to about half. Also, as in Comparative Example 1, a sharp decrease in sharpness was observed in an image having a sharp movement.

[0121] Comparative Examples 1 and 2 above, when equal the alignment direction of the liquid crystal of the opening and non-opening portion, the applied voltage giving a maximum transmittance is high, and the difference between the T _on and T _off is increased However, it was found that the sharpness of the image at the time of displaying a moving image also decreased.

[0122]

According to the present invention, excellent effects such as a low driving voltage of a horizontal electric field method having a wide viewing angle and a clear display of a moving image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a liquid crystal display device of the present invention and the orientation direction of liquid crystal.

FIG. 2 is a schematic cross-sectional view showing a structure of a conventional liquid crystal display device and an alignment direction of liquid crystal.

FIG. 3 is a schematic diagram showing a structure of one pixel of the liquid crystal display device of the present invention.

FIG. 4 is a schematic cross-sectional view showing one example of a method for manufacturing a liquid crystal display device of the present invention.

FIG. 5 is a schematic cross-sectional view showing one example of a method for manufacturing a liquid crystal display device of the present invention.

FIG. 6 is a schematic cross-sectional view showing one example of a method for manufacturing a liquid crystal display device of the present invention.

FIG. 7 is a diagram showing the drive voltage dependence of the response time of the liquid crystal display device of the present invention.

FIG. 8 is a diagram showing the drive voltage dependence of the transmittance of the liquid crystal display device of the present invention.

FIG. 9 is a schematic cross-sectional view showing one example of a method for manufacturing a liquid crystal display device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Common electrode, 2 ... Gate insulating film, 3 ... Signal electrode, 4 ...
Pixel electrode, 5: alignment film, 7: substrate, 8: polarizing plate, 9: electric field direction, 11: polarizing plate transmission axis direction, 12: scanning electrode, 1
3 ... amorphous silicon, 14 ... thin film transistor,
15: average orientation direction of liquid crystal in non-opening portion; 16: average orientation direction of liquid crystal in opening portion; 21: interface orientation direction of non-opening portion;
22: orientation direction of interface at opening, 23: orientation film, 24, 2
5: alignment processing unit, 26, 27: photomask, 30: black matrix.

Claims (6)

[Claims] 1. A pair of substrates, at least one of which is transparent;
A liquid crystal layer disposed between the pair of substrates, an electrode group formed on one of the pair of substrates and applying an electric field parallel to the substrate surface to the liquid crystal, and connected to the electrode groups; A plurality of active elements, an alignment layer disposed between the liquid crystal and the substrate, and an optical unit for changing optical characteristics according to an alignment state of the liquid crystal layer, and an aperture for transmitting light within one pixel. A liquid crystal display device of an active matrix type having a portion and a non-opening portion that does not transmit light, wherein the alignment direction of the liquid crystal layer in a state where no voltage is applied is different between the opening portion and the non-opening portion. Display device. 2. A pair of substrates at least one of which is transparent;
A liquid crystal layer disposed between the pair of substrates, an electrode group formed on one of the pair of substrates and applying an electric field parallel to the substrate surface to the liquid crystal, and connected to the electrode groups; A plurality of active elements, an alignment layer disposed between the liquid crystal and the substrate, and an optical unit for changing optical characteristics according to an alignment state of the liquid crystal layer, and an aperture for transmitting light within one pixel. A liquid crystal display device of an active matrix type having a portion and a non-opening portion that does not transmit light, wherein the alignment layer is close to the liquid crystal layer, and the alignment direction of the liquid crystal at the interface between the alignment layer and the liquid crystal layer is interface-aligned. The liquid crystal display device is characterized in that the interface orientation direction is different between the opening and the non-opening when the direction is defined as the direction. 3. The liquid crystal display device according to claim 1, wherein the alignment layer is formed of a photoreactive organic polymer film. 4. The liquid crystal display device according to claim 2, wherein an angle between the interface orientation direction and the electric field direction is larger in the opening than in the non-opening. 5. The liquid crystal display device according to claim 4, wherein the angle between the interface orientation direction and the electric field direction in the opening is 45 to 85 degrees. 6. A pair of substrates, at least one of which is transparent,
A liquid crystal layer disposed between the pair of substrates, an electrode group formed on one of the pair of substrates and applying an electric field parallel to the substrate surface to the liquid crystal, and connected to the electrode groups; A plurality of active elements, an alignment layer disposed between the liquid crystal and the substrate, and an optical unit for changing optical characteristics according to an alignment state of the liquid crystal layer, and an aperture for transmitting light within one pixel. A liquid crystal display device of an active matrix type having a portion and a non-opening portion that does not transmit light, wherein the alignment layer is close to the liquid crystal layer, and the alignment direction of the liquid crystal at the interface between the alignment layer and the liquid crystal layer is interface-aligned. In a method for manufacturing a liquid crystal display device, in which the interface orientation direction is different between an opening and a non-opening, the orientation layer is formed of a photopolymerizable photo-alignment material, and the opening (or non-opening) is formed. Shield and illuminate linearly polarized light at a specified angle. By selectively photopolymerizing and orienting by irradiating,
Next, the non-opening (or the opening) is irradiated with linearly polarized light at a predetermined angle to be photopolymerized and oriented, and the orientations of the opening and the non-opening are different from each other at a predetermined angle. A method for manufacturing a liquid crystal display device, comprising: