JPH09197365A - Electro-optic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electro-optic element which is free from display defects and has an excellent image grade by specifying the relation between the twist angle of liquid crystal regulated by a rotary polarization optical material and the twist angle of liquid crystal regulated by the orientation treatment applied on a base body. SOLUTION: A liquid crystal cell formed by holding a liquid crystal added with a rotary polarization optical material to induce twist between a pair of substrates is arranged between a pair of polarization plates. The value of ΔD is -28.5<=ΔD<=66.5, when the twist angle of the liquid crystal regulated by the rotary polarization optical material is denoted as Dc, the twist angle of the liquid crystal regulated by the orientation treatment applied on the substrate as Ds, and ΔD=[(Dc-Ds)/Ds]×100(%) is assumed. Further, the amt. of addition (C[wt.%]) of the rotary polarization optical material is regulated by C=X/(d×P) when the twist angle (Dc) is denoted as X, the cell thickness as (d) and the optical rotatory power possessed by the rotary polarization optical material as P. The conformity of the twist angle of the liquid crystals regulated by the rotary polarization optical material of the liquid crystal cell and the twist angle of the liquid crystals regulated by the orientation treatment applied on the substrate is thus improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electro-optical element.

[0002]

2. Description of the Related Art An electro-optical element using a conventional super twist nematic mode (hereinafter abbreviated as STN mode) is used in a state in which no voltage is applied and a state in which a selected voltage is applied, as disclosed in Japanese Patent Laid-Open No. 60-50511. It was colored.

An electro-optical element utilizing the conventional New Twisted Nematic mode (hereinafter abbreviated as NTN mode) which solves the above problems is disclosed in Japanese Patent Application No. 62-121.
No. 701, a liquid crystal cell (hereinafter referred to as a display cell) that performs a display in a state where a selection voltage is applied and an optically anisotropic body are sandwiched by a pair of polarizing plates, so that no voltage is applied and a selection voltage is applied. It was possible to make the hues of both appearances black and white.

[0004]

However, the above-mentioned STN
In the electro-optical element using the mode and the NTN mode, the twist angle (hereinafter abbreviated as Ds) defined by the substrate orientation treatment in the display cell and the liquid crystal cell as an optically anisotropic body (hereinafter referred to as the upper cell). If necessary, Ds of the display cell is Dss and Ds of the upper cell is Dsu.) And the twist angle (hereinafter abbreviated as Dc) of the liquid crystal defined by the addition of the optically active substance to the nematic liquid crystal. If the value is poor, the liquid crystal orientation will be disturbed. This is Dc <D
When s, a defect is called a low twist domain, and when Dc> Ds, a defect is called a lighting domain or an over twist domain. A defect occurs in the low-twist domain and the over-twist domain when no voltage is applied, and in the lighting domain when a selection voltage is applied.

Due to this defect, desired electro-optical characteristics cannot be obtained, and as a cause of deterioration of yield in mass production, productivity is greatly affected.

However, heretofore, no example has been found in which a preferable range of matching between Ds and Dc is defined to try to solve this problem.

Therefore, in the present invention, by solving such a problem and clarifying the allowable range of matching of Dc with Ds, an electro-optical element having excellent characteristics can be stably obtained and productivity is improved. The purpose is to

[0008]

An electro-optical element according to the present invention comprises a P-type nematic liquid crystal which is twisted and oriented and sandwiched between two opposing electrode substrates, and an optical rotatory substance is added to the nematic liquid crystal. In an electro-optical element including a liquid crystal cell that causes a helical twist angle in the thickness direction of the liquid crystal and a pair of polarizing plates disposed on both sides of the liquid crystal cell, the liquid crystal cell is defined by the addition of an optical rotatory substance to the liquid crystal. It is characterized in that the twist angle of the liquid crystal is in the range of −28.5% to + 66.5% with respect to the twist angle defined by the substrate orientation treatment.

Further, the electro-optical element is provided with at least one layer of an optically anisotropic body. Furthermore, the optically anisotropic body is a liquid crystal cell in which a twisted and oriented P-type nematic liquid crystal is sandwiched between two opposing substrates. Further, the liquid crystal cell in the electro-optical element and the liquid crystal cell which is an optically anisotropic body have different twist directions. Further, in the optically anisotropic liquid crystal cell, the twist angle of the liquid crystal defined by the addition of the optically active substance to the liquid crystal is -38. It is characterized by being in the range of 0% to + 76.0%.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Examples, but the present invention is not limited to the materials and conditions described in the Examples, and other materials, Similar effects can be obtained under other conditions.

[Embodiment 1] FIG. 1 is a sectional view schematically showing the structure of an electro-optical element of the present invention. In the figure, 101 is the upper polarizing plate, 102 is the upper cell, 103 is the upper substrate of the upper cell, 104 is the lower substrate of the upper cell, and 105.
Is a liquid crystal layer of the upper cell, 106 is a display cell, 107 is an upper electrode substrate of the display cell, 108 is a lower electrode substrate of the display cell,
109 is a liquid crystal layer of the display cell, and 110 is a lower polarizing plate. FIG. 2 is a diagram showing an example of the relationship of each axis of the electro-optical element of the present invention. In the figure, 201 is the rubbing direction of the lower electrode base of the display cell, 202 is the rubbing direction of the upper electrode base of the display cell, and 203 is the molecular axis of the liquid crystal molecules in the upper cell adjacent to the lower base of the upper cell. Direction, 204 is the direction of the molecular axis of liquid crystal molecules in the upper cell adjacent to the upper substrate of the upper cell, 205 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, and 206 is the polarization axis of the upper polarizing plate (absorption). Axis), 207 is a direction in which liquid crystal molecules in the display cell are twisted from top to bottom and its angle (Dss), 208
Is the angle formed by the rubbing direction 202 of the upper electrode substrate of the display cell with respect to the direction 203 of the molecular axis of liquid crystal molecules in the upper cell adjacent to the lower substrate of the upper cell, and 209 is the polarization axis (absorption axis) of the upper polarizing plate. An angle formed by the direction 204 of the molecular axis of liquid crystal molecules in the upper cell adjacent to the upper substrate of the upper cell with respect to the direction 206, 210 is the polarization axis (absorption of the lower polarizing plate with respect to the rubbing direction 101 of the lower electrode substrate of the display cell. An angle 211 formed by the direction 105 of the axis) indicates a direction (Dsu) in which the liquid crystal molecules in the upper cell are twisted from the top to the bottom. The counterclockwise direction is positive here.

In this embodiment, a P-type nematic liquid crystal is used, and one of its concrete mixtures is SS-4.
008 (manufactured by Chisso Corporation).

The amount of the optically active substance added is calculated from the following formula.

C = X / (d × P) (where C is the addition amount of the optically active substance [wt%], and X is
The twist angle Dc [deg], d is the cell thickness [μm], and P is the optical rotatory power of the optical rotatory substance.) The same applies to the following examples.

Example 1 of the present invention is shown in Table 1 for a display cell and in Table 2 for an upper cell. ΔD in the table is defined as follows.

ΔD = [(Dc-Ds) / Ds] × 100 In this embodiment, the display cell has Dss (= Ds) on the left 2
10 °, d = 6.0 μm, and the upper cell is Dsu
(= DS) was 210 ° to the right and d = 6.0 μm.

From Table 1, the display cell has a ΔD of -31.0%.
Then, the twist domain is generated, and ΔD is sixteen.
A lighting domain occurs at 9.0%. On the other hand, -28.
In the range of 5% ≦ ΔD ≦ + 66.5%, no domain was generated and excellent electro-optical characteristics were obtained.

In the cells above Table 2, ΔD is -40,
In 5%, a twist domain is generated, and +66.
A lighting domain occurs at 5% and an overtwist domain occurs at + 78.5%. For the upper cell, the lighting domain does not matter if voltage application is not required. Therefore,
An excellent optically anisotropic substance can be obtained in the range of −38.0% ≦ ΔD ≦ + 76.0%.

Although the NTN mode electro-optical element is described in detail in this embodiment, the values in Table 1 and Table 2 are STN.
It can be applied as it is to the electro-optical element of the mode. That is, Table 1 shows the left twist 210 ° twist S
Similar to the case of TN mode, Table 2 shows a right twist 210
The same as in the case of twisted STN mode. The same effect can be obtained in each of the following embodiments.

[0020]

[Table 1]

[0021]

[Table 2]

[Example-2] Table 2 shows Example-2 of the present invention.
The display cells are shown in the upper cell in Table 4. In the present embodiment, the display cell is Dss (= Ds) 240 ° to the left,
d = 6.0 μm, and the upper cell is Dsu (= Ds)
Was 210 ° to the right and d = 6.0 μm.

From Table 3, the display cell has a content of −29.0% ≦ ΔD.
It was found that excellent electro-optical characteristics could be obtained without the occurrence of domains within the range of ≤ + 66.5%.

The cells above Table 4 are -37.5. %
It was confirmed that an excellent optically anisotropic body could be obtained in the range of ≤ΔD≤ + 77.0% (when voltage application to the upper cell is unnecessary).

In this example, the allowable range was almost the same as that of Example-1, although the twist angle was different.

[0026]

[Table 3]

[0027]

[Table 4]

[Embodiment 3] In this embodiment, the D of the display cell is
ss (= Ds) to the left 120 °, 150 °, 180 °, 1
95 °, 225 °, 240 °, 270 °, 330 °, and Dsu (= Ds) of the upper cell is 120 °, 150 to the right.
°, 180 °, 195 °, 225 °, 240 °, 270
And 330 °, which correspond to each other. The cell thickness d was both set to 6.0 μ.

As a result, it was confirmed that all the angles had the same allowable range of ΔD as those in Examples 1 and 2, even though the twist angles were different.

The results are shown in Tables 5 and 6. Table 5 shows the case of the display cell, and excellent electro-optical characteristics were obtained in the range of −29.0% to + 66.5% without generation of domains. Further, Table 6 shows the case of the upper cell, which is -37.5 to +5.
No domain was generated in the range of 0.0%. further,
In addition, since the lighting domain is not a problem when voltage application is unnecessary for the upper cell, it goes without saying that -37.5% to + 77.0% is an appropriate range.

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

As described above, according to the present invention, it is possible to obtain an extremely useful effect of obtaining an electro-optical element having no defects and exhibiting excellent image quality.

[Brief description of drawings]

FIG. 1 is a model view showing the structure of electro-optical elements according to Examples-1, 2 and 3 of the present invention.

FIG. 2 is a diagram showing a relationship between axes of electro-optical elements according to Examples-1, 2 and 3 of the present invention.

[Explanation of symbols]

101 ... Upper polarizing plate 102 ... Upper cell 108 ... Upper substrate of upper cell 104 ... Lower substrate of upper cell 105 ... Liquid crystal layer of upper cell 106 ... Display cell 107 ... Display cell upper electrode substrate 108 Display cell lower electrode substrate 109 Display cell liquid crystal layer 110 Lower polarizing plate 201 Display cell lower electrode substrate rubbing direction 202 ... Rubbing direction of upper electrode substrate of display cell 203 ... Direction of molecular axis of liquid crystal molecules in upper cell adjacent to lower substrate of upper cell 204 ... Upper cell adjacent to upper substrate of upper cell 205. Direction of molecular axis of liquid crystal molecules in ... 205 ... Direction of polarization axis (absorption axis) of lower polarizing plate 206 ... Direction of polarization axis (absorption axis) of upper polarizing plate 207 ... In display cell The direction in which liquid crystal molecules twist from top to bottom Angle 208. The angle formed by the rubbing direction 202 of the upper electrode substrate of the display cell with respect to the direction 203 of the liquid crystal molecular axis in the upper cell adjacent to the lower substrate of the upper cell 209. Absorption axis) direction 20
The angle formed by the directions 204 of the molecular axes of the liquid crystal molecules in the upper cell adjacent to the upper substrate of the upper cell with respect to 6 210 ... Rubbing direction 1 of the lower electrode substrate of the display cell
Direction of the polarization axis (absorption axis) of the lower polarizing plate with respect to 01
Angle formed by 5 211 ... Direction and angle of liquid crystal molecules in upper cell twisted from top to bottom

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[Procedure amendment]

[Submission date] February 5, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

The electro-optical element of the present invention is provided with an optically active substance which causes a twist between a pair of substrates.
A display cell formed by sandwiching the added liquid crystal is used as a pair of polarizing plates.
The electro-optical element arranged between the
The twist angle of the liquid crystal defined by the substance is Dc,
Liquid crystal twist angle defined by the orientation treatment applied to the body
Ds, ΔD = [(Dc-Ds) / Ds] × 100
(%), The value of ΔD is −28.5 ≦ ΔD ≦ 6
It is 6.5 . Further, the addition amount of the optical rotatory substance (C [w
t%]), the twist angle (Dc) is X, the cell thickness is d, and the optical rotation is
When the optical rotation of the volatile substance is P, C = X / (d ×
P) . Specially
Sign .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

The electro-optical element of the present invention also comprises a pair of substrates.
Liquid crystal added with optically active substance that causes twist between plates
The display cell formed by sandwiching the
In the electro-optical element consisting of
Is a liquid crystal cell formed by sandwiching a liquid crystal between a pair of opposing substrates.
Optical anisotropic body consisting of
Specified by the optical rotatory substance of liquid crystal sandwiched between
The twist angle of the liquid crystal to be Dc, the alignment treatment applied to the substrate.
The twist angle of the liquid crystal is Ds, ΔD =
[(Dc-Ds) / Ds] × 100 (%),
The value of ΔD is −28.5 ≦ ΔD ≦ 66.5 . In addition, the liquid sandwiched between the optically anisotropic bodies
The twist angle of the liquid crystal defined by the optical rotatory substance of the crystal is D
c, a liquid crystal defined by the alignment treatment applied to the substrate
The twist angle of Ds, ΔD = [(Dc-Ds) / Ds] ×
When the value is 100 (%), the value of ΔD is −38.5 ≦ ΔD
It is characterized in that ≦ 76.0 .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

From Table 1, the display cell has a ΔD of -31.0%.
Then, a twist domain is generated, and ΔD is +6.
A lighting domain occurs at 9.0% . On the other hand, -28.
In the range of 5% ≦ ΔD ≦ + 66.5%, no domain was generated and excellent electro-optical characteristics were obtained.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

[0033]

As described above, according to the present invention, the liquid
Angle of liquid crystal defined by the optical rotatory substance of the cubic cell
And the liquid crystal defined by the alignment treatment applied to the substrate
By improving the compatibility with the twist angle, display defects
An electro-optical element exhibiting excellent image quality can be obtained. Ma
Defined by the optically active substance in the optically anisotropic body
The liquid crystal twist angle and the alignment treatment applied to the substrate
By improving the conformity with the twist angle of the liquid crystal to be determined,
However, electro-optic with excellent image quality without coloring
An element can be obtained .

Claims (5)

[Claims] 1. A liquid crystal in which a twisted and oriented P-type nematic liquid crystal is sandwiched between two opposing electrode substrates, and an optical rotatory substance is added to the nematic liquid crystal to generate a helical twist angle in the thickness direction of the device. In an electro-optical element comprising a cell and a pair of polarizing plates arranged on both sides of the liquid crystal cell, the twist angle of the liquid crystal defined by the addition of the optically active substance to the liquid crystal is defined by the substrate orientation treatment. -28.5% to + 66.5% with respect to the twist angle
The electro-optical element is characterized in that 2. The electro-optical element according to claim 1, wherein the electro-optical element includes at least one layer of an optically anisotropic body. 3. The electro-optical element according to claim 2, wherein the optically anisotropic body is a liquid crystal cell in which a twisted and oriented P-type nematic liquid crystal is sandwiched between two opposing substrates. . 4. The electro-optical element according to claim 3, wherein the liquid crystal cell in the electro-optical element and the liquid crystal cell which is an optically anisotropic body have different twist directions. 5. In the liquid crystal cell which is an optically anisotropic body, the twist angle of the liquid crystal defined by the addition of an optical rotatory substance to the liquid crystal is different from the twist angle defined by the substrate orientation treatment. The electro-optical element according to claim 4, wherein the range is from -38.0% to + 76.0%.