JP2001166341A - Liquid crystal element - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the voltage applied to transfer a nematic liquid crystal to a bend alignment state and shorten the application time. The A liquid crystal panel, when divided into the non-display area C in which a plurality of pixels A ₁ are arranged so as to surround the display area B which is adjacent the area B as shown in FIG. 2, the display area The distance between pixel A ₁ and pixel A ₁ in B is 15
μm or less, the nematic liquid crystal (not shown) in the non-display area C is set in a bend alignment state or a vertical alignment state, and further, before driving the liquid crystal panel, the pixel electrode 3 b
And a common electrode (not shown). By applying the voltage, the nematic liquid crystal 2 in the display area B is bent. Since the distance between the pixel A ₁ and the pixel A ₁ is narrow, the voltage applied for bending is low, and the application time is also shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device that performs light switching using a nematic liquid crystal.

[0002]

2. Description of the Related Art Conventionally, various types of liquid crystal panels (liquid crystal elements) for switching light using a nematic liquid crystal have been proposed and used. Hereinafter, this point will be described.

Generally, a twisted nematic (Tw) in which the rubbing directions of the upper and lower substrates are made orthogonal to each other.
Although an isotropic nematic liquid crystal panel is used, a liquid crystal panel in which the rubbing directions of the upper and lower substrates are set to be the same as each other so that the nematic liquid crystal exhibits a splay alignment is conventionally known (see FIG. 6).

In a liquid crystal panel exhibiting such a splay alignment, since the response speed of the liquid crystal is slow due to a backflow phenomenon in the response of the liquid crystal, the alignment state of the liquid crystal is bent from the splay alignment state by applying a voltage. A “π cell” in which the response speed is improved by changing to an alignment state was published by Bos et al. In 1983 (see FIG. 5).

An "OCB cell" in which the viewing angle characteristic is improved by performing phase compensation on such a liquid crystal panel is one of the following.
It was announced by Uchida et al. In 992.

[0006]

However, in the liquid crystal panel utilizing the bend alignment state as described above, the above voltage application process must be performed in order to change the liquid crystal from the splay alignment state to the bend alignment state. However, there is a problem that the processing takes time.

[0007] This point will be described. That is, since the orientation transition between the spray and the bend is not continuous and a disclination line exists between the two orientation states, a process of nucleation and growth thereof is required. In such a process, it is difficult to generate nuclei in all the regions, and at the same time, it is difficult to control the nucleation threshold, and it is necessary to apply a high voltage. Also, the growth speed of the bend region formed by the nucleation is higher as the applied voltage is higher, but the lower the applied voltage is, the lower the growth speed is,
There is a problem that the processing takes several seconds to several minutes. In an actual liquid crystal panel, there is also a problem that it is difficult for a bend region to grow via a pixel electrode. Some studies have been made on the method of applying a voltage to a TFT liquid crystal panel (IBM, IDW 1996, p133 "Ini.
tearization of Optically
Compensated Bend-mode LCD
s, Japanese Patent Laid-Open No. 9-185032).

[0008] To solve the above problems,
There are bend alignment cells having a large pretilt, and various types have been published. That is, a π cell with a pretilt of 50 to 51 ° is a P.I. J. Bo
and published by Kogakuin University at the 5th Japan Liquid Crystal Symposium in 1979 (preprints, p. 166-) and also disclosed in JP-A-55-142316. However, when the pretilt is increased in this way, there is a problem that the retardation width obtained by turning on and off the voltage becomes very narrow, and the transmittance of the liquid crystal panel itself is reduced.

When the power supply of the liquid crystal panel is turned off, the nematic liquid crystal in the bend alignment state returns to the splay alignment state. When the power supply of the liquid crystal panel is turned on again, the nematic liquid crystal changes from the splay alignment state. There is a problem that it is necessary to perform a voltage application process again for transition to the bend alignment state.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal element which prevents a voltage application process from being performed for a long time.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes a pair of substrates arranged with a predetermined gap therebetween, and a nematic liquid crystal arranged in a gap between these substrates. At least one first electrode arranged along one of the substrates, a plurality of second electrodes arranged so as to sandwich the nematic liquid crystal together with the first electrode to constitute a plurality of pixels, and a uniaxial orientation. A pair of alignment control films disposed on both sides of the liquid crystal so that the processing direction is the same and in contact with the nematic liquid crystal, and the voltage is applied between the first electrode and the second electrode. In a liquid crystal element in which the nematic liquid crystal is driven by a drive voltage, a display area in which the plurality of pixels are arranged to display an image, and an image in which the plurality of pixels are not arranged and an image is displayed. A non-display area, and a distance between the adjacent second electrodes is set to 15 μm or less, and a first voltage is applied between the first electrode and the second electrode. The nematic liquid crystal in the display area is stabilized in a bend alignment state, and the nematic liquid crystal in the non-display area is stabilized in a bend alignment state or a vertical alignment state.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the present invention will be described. (1) First, a liquid crystal device according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a cross-sectional view showing an example of the structure of the liquid crystal element according to the present invention, FIG. 2 is a plan view showing an example of the structure of the liquid crystal element according to the present invention, and FIG. FIG. 4 is a plan view showing another example, and FIG. 4 is a timing chart showing an example of a method for driving a liquid crystal element according to the present invention.

The liquid crystal element according to the present embodiment comprises a pair of substrates 1a and 1b arranged with a predetermined gap therebetween, as shown by a symbol P in FIG. 1, for example, and these substrates 1a and 1b.
b), and a nematic liquid crystal 2 disposed in the gap b. Then, at least 1 is set along one of the substrates 1a.
One first electrode 3a and the other substrate 1b
(See FIG. 2), and the first electrode 3a and the second electrode 3b are arranged so as to sandwich the nematic liquid crystal 2 to form a plurality of pixels A ₁ . Make up. The nematic liquid crystal 2
A pair of alignment control films 4a and 4b are arranged on both sides of the liquid crystal 2 so as to be in contact with the nematic liquid crystal 2, and the uniaxial alignment processing directions 7a and 7a applied to these alignment control films 4a and 4b are arranged.
7b is set to be in the same direction.

[0014] Here, * as indicated by reference numeral B in FIG. 2, the plurality of optionally pixels A ₁ is disposed to the display area of the area on which an image is displayed, as indicated at C in * 2, area in which the plurality of pixels a ₁ is not displayed image not disposed hide (i.e., one of the electrodes 3a and 3b only one electrode 3a is disposed, 3b area not disposed both are) and area, as indicated at a ₂ in * 2, portions between the pixel a ₁ and a pixel a ₁ in the display area B (i.e., the portion corresponding to the mutual spacing of the second electrode 3b to be adjacent) Is an inter-pixel portion.

[0015] Then, the mutual spacing of the second electrode 3b to be adjacent (that is, the width of the inter-pixel portion A ₂₎ is set to 15μm or less.

The liquid crystal element P drives the nematic liquid crystal 2 based on the application of a driving voltage between the first electrode 3a and the second electrode 3b in the display area B, so that an image is displayed. The first electrode 3a and the second electrode 3 are displayed before such normal driving is performed.
and a first voltage (a voltage equal to or higher than a voltage that antagonizes the bend-spray).

According to the present embodiment, the nematic liquid crystal 2 in the pixel portion A ₁ is formed based on the application of the first voltage between the first electrode 3 a and the second electrode 3 b as described above. The bend alignment state is stabilized. Furthermore, since the mutual distance between the second electrode 3b is adjacent is set smaller than 15μm as described above, the transverse electric field caused by the first voltage to the nematic liquid crystal 2 of the inter-pixel portion A ₂ applied It is the result in even nematic liquid crystal 2 of the moiety a ₂ becomes to be stabilized in the bend alignment state similar. That is, according to this embodiment, the display area of the first voltage based on the applied, composed of pixels portion A ₁ and the inter-pixel portion A ₂ between the second electrode 3b and the first electrode 3a The nematic liquid crystal 2 in B is stabilized in a bend alignment state.

On the other hand, the nematic liquid crystal 2 in the non-display area C is stabilized in a bend alignment state or a vertical alignment state.

As a method of bringing the nematic liquid crystal 2 into the above-described alignment state, a method of making the pretilt angle different between the display area B and the non-display area C can be considered. And the non-display area C, the orientation control film 4
a, 4b are made of different materials (alignment film types),
a method of making the pretilt different even when the same strength rubbing treatment is performed on the entire surfaces of the a and 4b, and * the alignment control film 4 in the display area B and the non-display area C.
A method in which the pretilt is made different by changing the uniaxial alignment processing conditions without changing the materials (alignment film types) of a and 4b, * a specific material is used for the alignment control films 4a and 4b,
A method in which the alignment treatment is not performed in the non-display area C is considered, but is not necessarily limited to these methods.

As a method for bringing the nematic liquid crystal 2 in the non-display area C into a bend alignment state, besides the above-described method of controlling the alignment, * a third electrode separate from the second electrode 3b (see FIG. 3); Reference numeral 5) is disposed in the non-display area C, and * the second electrode 5 is connected to the nematic liquid crystal 2 via the third electrode 5.
A method of applying a voltage can be given.

If these methods are adopted, the nematic liquid crystal 2 in the display area B is stabilized in a bend alignment state or a twist state. This is not to say that there is no possibility of dislocation. Therefore, even after driving the liquid crystal element P once by applying the driving voltage, the first electrode 3a and the second electrode 3b can be connected between the first electrode 3a and the second electrode 3b.
It is preferable to re-stabilize the nematic liquid crystal 2 dislocated in the splay alignment state to the bend alignment state by applying a voltage again (refresh driving).

The application of the first voltage may be performed at regular intervals (for example, every few seconds, every few minutes, or every day) during driving of the liquid crystal element. FIG. 4 is a diagram showing an example in which refresh driving is performed in the active matrix type liquid crystal element every 1 s for a predetermined period, and FIG. 4A shows a gate voltage applied to the gate of the switching element 10 (details will be described later). (b) it is (to be described in detail later) the source of the switching element 10 showing the drive voltage and the first voltages V ₁ is applied to. (2) Next, the reason why the nematic liquid crystal 2 is brought into the above-described alignment state will be described.

When the pretilt angle is about several degrees to about 50 degrees, the splay alignment state is stable when no voltage is applied, but when the first voltage is applied to such a liquid crystal 2, the liquid crystal 2 becomes The dislocation is generated while generating the disclination to be in a bend alignment state. However, conventionally, it is necessary to apply a high voltage for a long time, and if the application of the first voltage is stopped or the applied voltage is reduced, the liquid crystal 2 returns from the bend alignment state to the splay alignment state again. Therefore, in order to maintain the above-described bend alignment state, it is necessary to keep applying the first voltage (a voltage equal to or higher than the voltage at which the bend and splay alignment states oppose each other).

By the way, the dislocation from the bend alignment state to the splay alignment state as described above is caused by the portion that was not displaced into the bend alignment state only by application of the first voltage (ie, the portion where the bend alignment state did not occur).
It has been clarified by the study of the present inventors that the part which remains in the splay alignment state) becomes a nucleus and spreads. A portion considered as a core portion is a portion where the first electrode 3a and the second electrode 3b are not arranged so as to face each other,
Specifically, the above-described non-display area C and the inter-pixel portion A ₂
And

According to the present embodiment, the liquid crystal 2 in the non-display area C stabilizes at a bend alignment state or a vertical alignment state, the liquid crystal 2 of the inter-pixel portion A ₂ is allowed to stabilize at the bend orientation state, A portion which easily becomes a nucleus of dislocation to the splay alignment state is theoretically lost, and as a result, the display area B
Is stabilized in a bend alignment state or a twist state.

FIG. 5 is a schematic view showing a bend alignment state, FIG. 6 is a schematic view showing a splay alignment state, and FIG. 7 is a schematic view showing a twist alignment state. Of these, the twist alignment state is known to continuously change to a bend alignment state without involving disclination. (3) Next, the structure of the liquid crystal element P described above will be supplemented.

The above-mentioned liquid crystal element P may be of a transmissive type or a reflective type, but it is necessary to appropriately select the material and structure of each member depending on whether the type is a transmissive type or a reflective type (details will be described later). ).

Further, the liquid crystal element P described above may be a simple matrix type, each pixel A ₁ is very effective better to an active matrix type by arranging the switching element 10 (described in detail later).

Further, as shown in FIG. 8, a uniaxial phase compensator having a positive retardation (one obtained by superposing a plurality of retardation films) 62a may be arranged along the liquid crystal element P. Thus, the retardation of light passing through the liquid crystal layer at a predetermined voltage value can be canceled, and optical compensation for black display at the voltage value can be performed. In this case, the liquid crystal molecules in the central portion of the liquid crystal layer have a large component in the normal direction of the substrate when a voltage is applied, which causes deterioration of the viewing angle characteristics. By using the phase compensation plate 62b (R <0) having a relatively small component and a negative retardation, the retardation difference between the direction perpendicular to the substrate and the direction horizontal to the substrate in the liquid crystal layer is corrected to improve the viewing angle characteristics. It is preferred to improve. Note that a biaxial phase compensator having both functions may be used instead of the two phase compensators 62a and 62b described above.

Further, a color filter or a flattening film may be arranged on at least one of the substrates 1a and 1b so that a color display can be performed.

In the liquid crystal device according to the present invention,
Using a nematic liquid crystal as described above, if a specific liquid crystal alignment is formed by forming a specific alignment control film, the material, shape, size,
The manufacturing method and the like are not particularly limited, and the technology of the conventional liquid crystal element can be applied. (4) Next, an example of an active matrix type liquid crystal element will be described with reference to FIGS. 1 and 2 are merely examples, and the present invention is not limited thereto.

The active matrix type liquid crystal element P is
As shown in FIG. 1, a pair of substrates 1a and 1b are provided with a predetermined gap therebetween, and a common electrode 3a as a first electrode, an insulating layer 6a and an alignment layer are provided on the entire surface of one of the substrates 1a. The control film 4a is formed. In the alignment control film 4a, a vertical alignment film region is formed in the non-display area C, and a horizontal alignment film region is formed in the display area B.

[0033] Further, the other substrate 1b, as shown in FIG. 2, the scanning signal lines G _1, G _2, ... are arranged in large numbers in the X direction, the scanning signal lines G _1, G _2, ... Are arranged in the Y direction in the figure in a state in which the information signal lines S ₁ , S ₂ ,. Further, the scanning signal lines G ₁ , G ₂ ,... Are connected to the scanning signal applying circuit 51 and the information signal lines S
_1, S _2, ... it is connected to the information signal application circuit 52.

The scanning signal lines G ₁ , G ₂ ,
, And each pixel A _{1 at} the intersection of the information signal lines S ₁ , S ₂ ,.
Are provided with a TFT 10 as a switching element, a pixel electrode 3b as a second electrode, and the like.

As shown in FIG. 1, the TFT 10 includes a gate electrode 10a formed on the surface of the substrate 1b, a gate insulating film 6b formed substantially over the entire surface of the substrate 1b so as to cover the gate electrode 10a, A semiconductor layer 10b formed at a position corresponding to the electrode 10a, an ohmic contact layer 10c, a source electrode 10d, and a drain electrode 10
e, an insulating layer 10f and a passivation layer 10g. The gate electrode 10a is connected to the scanning signal line G described above.
_1, G _2, is connected to ..., the source electrode 10d is the information signal line S _1, S _2, and is connected to ....

On the other hand, the pixel electrode 3 on the surface of the substrate 1b
b, a storage capacitor electrode 11 is formed at a position overlapping with the horizontal alignment film 4b so as to cover the pixel electrode 3b and the TFT 10.
Are formed.

When the above-mentioned liquid crystal element P is of a transmissive type, * a transparent material such as glass or plastic is used for both substrates 1a and 1b, and * an ITO (common electrode) is used for the common electrode 3a and the pixel electrode 3b. It is preferable to use a transparent conductive material such as indium tin oxide) and to arrange the polarizers 63a and 63b so as to sandwich the liquid crystal element P as shown in FIG. Where IT
The O film is preferably formed to a thickness of about 150 nm by a vacuum film formation method. The polarizers 63a and 63b are arranged in crossed Nicols, and the polarization axis is set to 45 with respect to the rubbing direction 64 of the orientation control films 4a and 4b. ° It is good to arrange so that it is inclined.

When the liquid crystal element P is of the reflection type, * an opaque material such as a silicon substrate is used for the substrate 1a or 1b which is not arranged on the side of the observer; * the pixel electrode 3b has a reflectance. It is preferable to form the pixel electrode 3b also as a reflection plate by using a metal having a high density.

On the other hand, regardless of whether the liquid crystal element P is of the transmission type or the reflection type, the semiconductor layer 10b is made of amorphous silicon (a-Si) or polycrystalline silicon (p-type).
-Si) may be used. When amorphous silicon is used, hydrogen-diluted monosilane (SiH ₄ ) is removed by glow discharge decomposition (plasma CVD) for about 300 hours.
It may be used by depositing it on a glass substrate at a temperature of about 200 nm with a thickness of about 200 nm.

The ohmic contact layer 10c is
For example, the n ⁺ a-Si layer is preferably doped with phosphorus.

Further, as the gate insulating film 6b, silicon nitride (SiN _x ) is used and formed by a glow discharge decomposition method.

The gate electrode 10a and the source electrode 10
A metal material such as aluminum is used for d, the drain electrode 10e, and the storage capacitor electrode 11. When the area of the storage capacitor electrode 11 is large, a transparent conductive material such as ITO may be used.

Further, Ta ₂ O ₅ or the like is used for the insulating layer 6a, and is deposited to a thickness of about 100 nm by a vacuum film forming method. Further, the insulating layer 10f and the passivation film 10
Silicon nitride is used for g.

Next, a method for driving a liquid crystal element according to the present invention will be described.
This will be described with reference to FIG. Here, FIG.
Timing showing an example of a method for driving a liquid crystal element according to the invention
It is a chart diagram, (a) is the first scanning signal line G₁ Mark on
A diagram showing a waveform of a scanning signal to be applied and an application timing,
(b) is the second scanning signal line G_Two Of the scanning signal applied to
FIG. 9C is a diagram showing waveforms and application timings, and FIG.
Scan signal line G _n Of the scanning signal applied to
(D) shows the first information signal line
S₁ And waveform of information signal (drive voltage) applied to
FIG. 7E shows the timing. FIG. 7E shows the first scanning signal line G.₁ When
First information signal line S₁ Pixel A at the intersection with₁ Of liquid crystal 2
FIG. 7 is a diagram illustrating a state of a change in applied voltage.

When driving the liquid crystal element, FIG.
~ Each scanning signal lines G ₁ from the scanning signal application circuit 51 to the scanning signal as shown in (c), G _2, when line-sequentially by applied to ..., each TFT10 are turned on. In synchronization with this scanning signal, the information signal applying circuit 52 sends information signal lines S ₁ , S _1
When an information signal (drive voltage) having predetermined gradation display information is applied to ₂ ,... As illustrated in FIG.
The pixel electrode 3b of the selected pixel A ₁ is applied the voltage through the TFT 10, the liquid crystal 2 performs a predetermined gradation display.

In the present invention, prior to the application of the driving voltage as described above, the liquid crystal 2 is displaced to a bend alignment state or the like by applying a first voltage to the liquid crystal 2 or the like.

Even when the liquid crystal element P according to the present invention is driven in the bend alignment state, a voltage higher than the holding voltage (voltage for maintaining the bend alignment state) is applied to the lower drive voltage side. The response speed can be further improved. (5) Next, effects of the present embodiment will be described.

According to the present embodiment, a low voltage can be used when the liquid crystal 2 is changed from the splay alignment state to the bend alignment state by performing a voltage application process. As a result, power consumption is reduced and low-voltage driving is possible.
Further, the voltage application time is shortened.

[0049]

The present invention will be described below in more detail with reference to examples. (Embodiment 1) In this embodiment, a pair of glass substrates 1a, 1
b, an experimental liquid crystal panel was prepared by sandwiching the nematic liquid crystal 2 between them, but transparent electrodes (first and second electrodes) 13a, 13b were formed on the surfaces of the glass substrates 1a, 1b by ITO.
(Indium Tin Oxide)
The orientation control film 4 covers the transparent electrodes 13a and 13b.
a and 4b were formed. Further, a spacer was arranged in the gap between the glass substrates 1a and 1b to define the gap. In addition,
One transparent electrode 13a was formed on almost the entire surface of the glass substrate 1a as shown in FIG. 10 (a), and a plurality of other transparent electrodes 13b were arranged for each pixel as shown in FIG. 10 (b).

Here, the transparent electrodes 13a and 13b are
It was formed to a thickness of 00 ° by vapor deposition and patterning of an ITO film. Further, with respect to one of the transparent electrodes 13b, the interval between adjacent ones was set to 15 μm.

Further, the alignment control films 4a and 4b are the same as those of * JALS2022 (a vertical alignment film manufactured by JAR).
% Solution is spin coated at 1500 revolutions / min, pre-baked at a temperature of 80 ° C. for 2 minutes, and baked at a temperature of 200 ° C. for 50 minutes. The thickness of the orientation control films 4a and 4b was measured with an ellipsometer (ESM-1A, manufactured by Japan Vacuum Engineering Co., Ltd.) and found to be 150 °.

The orientation control films 4a and 4b were subjected to a rubbing treatment. In this rubbing process, a masking process was performed on the non-display area C around the display area using a 2 mm polyimide tape. For this rubbing treatment, a rubbing roller having a diameter of 80 mm to which a cotton flocking cloth was stuck was used.
m, the amount of pressing into the substrate surface was 1.2 mm, and the feed speed of the substrates 1a and 1b was 10 mm / s.

Then, spacers having an average particle size of 6 μm are sprayed on one of the glass substrates
a and 1b were bonded together.

Thereafter, a non-cholesteric F-type nematic liquid crystal (KN-5030 manufactured by Chisso Corporation) 2 was injected into the gap between the substrates at reduced pressure and room temperature, and re-aligned at a temperature of 100 ° C. At this time, the liquid crystal 2 was stable in the splay state in the display area B.

Next, a rectangular wave voltage (± 1
0V, 30 Hz) the transparent electrodes 13a, was applied several minutes 13b, it becomes the bend alignment state liquid crystal 2 of the pixel portion A ₁ and the inter-pixel portion A ₂ is in seconds, spray orientation from the non-display area C around the display area No state was generated. When the applied voltage is removed, the liquid crystal 2
Was stable in the twisted state, and remained in the twisted state even when the liquid crystal panel was left for about one day.

The retardation of the liquid crystal panel prepared in this example was measured using a Berek compensator, and a retardation width of 200 nm was obtained from the required holding voltage (voltage applied to maintain the bend alignment state). When the drive voltage width that can be taken is determined, it is 0.7 to 3.
It became 5V.

By the way, in the present embodiment, after applying the rectangular wave voltage, in a low voltage region, a twisted alignment state was observed and the amount of transmitted light tended to decrease, so that a holding voltage of about 0.7 V was applied to the electrode. 13a and 13b were applied to maintain the bend alignment state. Since the initial alignment of the liquid crystal 2 was in the twist alignment state, the liquid crystal 2 was quickly transferred to the bend alignment state in a short time of about 20 ms when 0.7 V was applied.

The relationship between the retardation and the transmittance is as follows.

[0059]

I / I ₀ = sin ² 2θ · sin ² (Δnd / λ) π I; transmitted light amount I ₀ ; incident light amount θ; angle between polarization axis and rubbing axis Δn; liquid crystal Δn d; cell thickness λ; wavelength of light The transmittance I / I ₀ in the above equation becomes maximum when θ is 45 degrees. The wavelength λ of light is generally about 550 nm. Δn
From the above equation, it can be found that the transmittance I / I ₀ becomes maximum when d is about 270 nm. However, natural light contains various wavelengths, and this design value causes a problem that the cell becomes yellowish due to wavelength dispersion. Yes, in the evaluation of the present invention, a 200 nm design was used.

The bend holding voltages and the like of Examples 1, 2 and Comparative Examples 1 and 2 are summarized in the following table.

[0061]

[Table 1] (Embodiment 2) In this embodiment, a liquid crystal panel P similar to that of Embodiment 1 was prepared, but the spin rotation speed at the time of forming the alignment control films 4a and 4b was 1000 rotations / min, and the film thickness was 350 °. And Further, the pretilt angle was set to 25 °, which was larger than that in Example 1. Other configurations and manufacturing methods were the same as those in the first embodiment.

The liquid crystal 2 was stable in a spray state immediately after realignment.

Next, a rectangular wave voltage (± 1
0V, 30 Hz) the transparent electrodes 13a, was applied for several minutes to 13b, the liquid crystal 2 of the pixel portion A ₁ and the inter-pixel portion A ₂ becomes a bend alignment state similar to a few seconds as in Example 1, hidden near the display area No splay alignment state was generated from area C either. Then, even if the applied voltage was removed and the liquid crystal panel was allowed to stand for about one day, the liquid crystal 2 was maintained in the bend alignment state because the pretilt angle was large, and the application of the holding voltage was unnecessary.

When a drive voltage width capable of obtaining a retardation width of 200 nm was obtained, it was 0 to 4.5 V. Comparative Example 1 The liquid crystal panel produced in this comparative example has substantially the same configuration as that produced in Example 1, except that the distance between adjacent transparent electrodes 13b is not 15 μm but 17 μm.
μm. Other configurations and manufacturing methods were the same.

When the liquid crystal 2 was injected or realigned in the same manner as in Example 1, the liquid crystal 2 was stable in the splay alignment.

[0066] Thereafter, similarly rectangular wave voltage as in Example 1 (first voltage) to a transparent electrode 13a, was applied several minutes 13b, although the liquid crystal 2 pixel portions A ₁ became bend alignment state, between pixels the liquid crystal 2 of part a ₂ remained of the splay alignment state. When the applied voltage was removed,
The liquid crystal 2 in the pixel portion A ₁ which was in the bend alignment state immediately transposed to the splay alignment state.

In order to maintain the liquid crystal 2 in the bend alignment state, a holding voltage of about 1.5 V is required.
The following voltages are the non-display area C and the inter-pixel portion A ₂ splay alignment state spread as a core, the liquid crystal 2 of the pixel portions A ₁ became a splay alignment state. For this reason, the optical characteristics of the liquid crystal panel became non-uniform, and the response speed was greatly reduced.

In order to displace the liquid crystal 2 once in the splay alignment state to the bend alignment state, it was necessary to apply a voltage of about 7 V for about 1 minute. (Comparative Example 2) The liquid crystal panel prepared in the present comparative example has substantially the same configuration as the liquid crystal panel prepared in Example 1, except that the distance between the adjacent transparent electrodes 13b is not 15 μm but 17 μm.
μm. Other configurations and manufacturing methods were the same.

When the liquid crystal 2 was injected or realigned in the same manner as in Example 1, the liquid crystal 2 was stable in the splay alignment.

[0070] Thereafter, similarly rectangular wave voltage as in Example 1 (first voltage) to a transparent electrode 13a, was applied several minutes 13b, although the liquid crystal 2 pixel portions A ₁ became bend alignment state, between pixels the liquid crystal 2 of part a ₂ remained of the splay alignment state. When the applied voltage was removed,
The liquid crystal 2 in the pixel portion A ₁ which was in the bend alignment state immediately transposed to the splay alignment state.

In order to maintain the liquid crystal 2 in the bend alignment state, a holding voltage of about 1.5 V is required.
The following voltages are the non-display area C and the inter-pixel portion A ₂ splay alignment state spread as a core, the liquid crystal 2 of the pixel portions A ₁ became a splay alignment state. For this reason, the optical characteristics of the liquid crystal panel became non-uniform, and the response speed was greatly reduced.

In order to displace the liquid crystal 2 once in the splay alignment state to the bend alignment state, it was necessary to apply a voltage of about 7 V for about 1 minute. Embodiment 3 In this embodiment, an active matrix type liquid crystal panel (liquid crystal element) P shown in FIGS. 1 and 2 was prepared. The adjacent pixel electrode (second electrode) 3b
Were set at 15 μm. Further, the uniaxial phase compensation film (75 nm) was arranged in a direction to offset the retardation of the black display voltage during normally white driving.

According to the present embodiment, the liquid crystal 2 immediately after the realignment was in the splay alignment state.

When the signal shown in FIG. 11 is applied to the liquid crystal panel P, the liquid crystal 2 in the display area is immediately in a bend alignment state. When the applied voltage is removed, the liquid crystal 2 in the display area is in a twist alignment state. Was. In this example, the holding voltage required to maintain the bend alignment state was 0.7V.

When the relationship between the amount of transmitted light and the voltage was measured, the driving voltage was 0.7 to 4.5 V. (Embodiment 4) In this embodiment, an active matrix type liquid crystal panel similar to that of Embodiment 3 was prepared, but a non-display area C of one glass substrate 1b was provided with a frame-shaped ITO as shown in FIG. The electrode (third electrode) 5 was formed so as to face the common electrode (first electrode) 3a. The distance between the adjacent pixel electrodes (second electrodes) 3b was 15 μm.

In driving the liquid crystal panel, a rectangular wave (voltage for bending) of 7 V is applied between the ITO electrode 5 and the common electrode 3a, while FIG.
As shown in FIGS. 1 (a) to (c), a scanning signal is applied to each scanning signal line G.
_1, G _2, ... continue to apply a line sequential, the information signal line S
_1, S _2, the ... applying voltage as illustrated in FIG. (D).

As a result, the liquid crystal 2 in the display area was stable in the twisted state even when the applied voltage was removed.

In this embodiment, phase compensation was performed in the same manner as in the third embodiment.

When the relationship between the amount of transmitted light and the voltage was measured, the driving voltage was 0.7 to 4.5 V, and the holding voltage required was about 0.7 V. (Embodiment 5) In the liquid crystal panel prepared in Embodiment 3, when white display is performed for a long time of, for example, about one day, a splay alignment state occurs in a part. In this embodiment, as shown in FIG. A reset voltage (first voltage) was applied every second.

According to this embodiment, the splay alignment state as in the third embodiment did not occur.

[0081]

As described above, according to the present invention,
When the nematic liquid crystal is transitioned from the splay alignment state to the bend alignment state by performing a voltage application process, a low voltage can be used. As a result, power consumption is reduced,
Low voltage driving is also possible. Further, the voltage application time is shortened.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the structure of a liquid crystal panel according to the present invention.

FIG. 2 is a plan view showing an example of the structure of the liquid crystal panel according to the present invention.

FIG. 3 is a plan view showing another example of the structure of the liquid crystal panel according to the present invention.

FIG. 4 is a diagram showing an example in which refresh driving is performed at regular intervals in an active matrix liquid crystal element.

FIG. 5 is a schematic view showing a bend alignment state.

FIG. 6 is a schematic view showing a splay alignment state.

FIG. 7 is a schematic view showing a twist alignment state.

FIG. 8 is a diagram for explaining an example in which a phase compensation member is arranged.

FIG. 9 is a timing chart illustrating an example of a method for driving a liquid crystal element according to the present invention.

FIG. 10 is a plan view showing still another example of the structure of the liquid crystal panel according to the present invention.

FIG. 11 is a timing chart showing another example of a method for driving a liquid crystal element according to the present invention.

[Explanation of symbols]

1a, 1b Glass substrate (substrate) 2 Nematic liquid crystal 3a Common electrode (first electrode) 3b Pixel electrode (second electrode) 4a, 4b Alignment control film 5 ITO electrode (third electrode) 10 TFT (switching element) 13a Common electrode (First electrode) 13b Pixel electrode (second electrode) A ₁ pixel B Display area C Non-display area P Liquid crystal panel (liquid crystal element)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hirohide Munekata 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H088 FA02 GA02 HA04 HA08 HA12 MA07 MA20 2H090 HB04X HD03 LA02 LA04 LA15 MA01 MA11 5C094 AA13 AA22 AA24 AA48 AA53 AA56 BA03 BA43 CA19 DA13 DB01 DB04 DB10 EA04 EA05 EA07 EA10 EB02 ED20 FA01 FB12 FB15 GA10 JA08

Claims (5)

[Claims] 1. A pair of substrates arranged with a predetermined gap therebetween, a nematic liquid crystal arranged in a gap between these substrates, and at least one first electrode arranged along one of the substrates. A plurality of second electrodes arranged so as to sandwich the nematic liquid crystal together with the first electrode to constitute a plurality of pixels, and a direction of the uniaxial alignment treatment is the same, and the liquid crystal is arranged so as to be in contact with the nematic liquid crystal. A pair of alignment control films disposed on both sides, and wherein the nematic liquid crystal is driven by a driving voltage applied between the first electrode and the second electrode; A display area in which pixels are arranged and an image is displayed, and a non-display area in which the plurality of pixels are not arranged and an image is not displayed. The distance is set to 15 μm or less, and the nematic liquid crystal in the display area is stabilized in a bend alignment state based on the application of the first voltage between the first electrode and the second electrode; A liquid crystal element, wherein the nematic liquid crystal in a non-display area is stabilized in a bend alignment state or a vertical alignment state. 2. The pre-tilt angle in the alignment control film is different between the display area and the non-display area so that the nematic liquid crystal in the non-display area is stabilized in a bend alignment state or a vertical alignment state. The liquid crystal device according to claim 1, wherein: 3. A third electrode separate from the second electrode is arranged in the non-display area, and a second voltage is applied to the nematic liquid crystal through the third electrode, whereby the area is reduced. The liquid crystal device according to claim 1, wherein the nematic liquid crystal is stabilized in a bend alignment state or a vertical alignment state. 4. The liquid crystal device according to claim 1, wherein a switching element is arranged for each pixel. 5. The method according to claim 1, further comprising:
The liquid crystal device according to any one of claims 1 to 4, wherein a first voltage is applied between an electrode and the second electrode.