JPS636524A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To enlarge a contrast ratio, and also, to execute a good display by reducing a color shade, by forming a transparent electrode and an oriented layer on the inside surface of a glass substrate. CONSTITUTION:Transparent electrodes 3, 4 and oriented layers 5, 6 are formed on glass substrates 1, 2, the substrates 1, 2 are opposed to each other at a necessary minute interval, its peripheral part is stuck with a sealing agent 7, by which a cell is formed. A nematic liquid crystal 8 to which a chiral substance has been added is injected into this cell. The liquid crystal 8 becomes a molecular arrangement having an angle of torsion within a range of 200 deg.-270 deg. between the substrates 1, 2 by an orientation processing. Also, this orientation processing is executed by rubbing so that the oriented layers 5, 6 become a low tilt angle of <=5 deg.. As for its rubbing direction, an arrow b1 and an arrow b2 become a reference in the substrate 1 side and the substrate 2 side, respectively. On the other hand, a polarizing plate 10 is stuck so that an included angle of its polarization axis c2 and the arrow b1 in the oriented layer 5 becomes '0' deg.-60 deg., and a polarizing plate 9 is stuck so that an included angle of its polarization axis c1 and the polarization axis c2 of the polarizing plate 10 becomes the same angle as the foregoing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element used for high time division drive dot matrix display and the like.

[Conventional technology]

Liquid crystal display elements with 9Q'TN array cells are widely used in various fields. This 90'TN array cell has an angle of ±45° with respect to the cell center line X (or y) as shown in Figure 7.
The direction of is defined as the rubbing direction, and the angle A formed by the rubbing direction (arrow a1 for the front and arrow a2 for the rear) of the front substrate and the rear substrate is approximately 90'.

Further, the polarizing plate is attached so that its polarization axis substantially coincides with the rubbing direction. Note that a very small amount of chiral material is contained in the liquid crystal cell to prevent reverse twist.

[Problem that the invention seeks to solve]

Since this liquid crystal display element performs display by controlling the transmission and blocking of light using the optical rotation of the liquid crystal cell, the contrast has a large viewing angle dependence, and the contrast is low when viewed from the front.

Additionally, there are drawbacks such as the background color being gray and dull, and the viewing angle being narrow.

In addition, the angle A formed by the rubbing direction of the front board and the back board
is larger than 90° and smaller than 180°, and the angle between the polarization axes on the front and back sides of the polarizing plate is 0' - 90',
There are some that are attached so that the included angle with the rubbing direction is 0° to 60°, but both the contrast ratio and viewing angle are poor.

[Means for solving problems]

In the present invention, a transparent electrode and an alignment layer are formed on the inward facing surface, and the tilt angle is 5° or less, and the tilt angle is 200° to 200°.
Two glass substrates that have been subjected to an alignment treatment by rubbing so as to have a twist angle in the range of 270° are prepared so that the product Δn-d of the thickness d of the liquid crystal layer and the refractive index anisotropy Δn of the liquid crystal is 0. 8μ
A cell is formed by facing each other at a minute interval of 1.0 μm to 1.0 μm and bonding the peripheral edges with a sealant, and injecting a nematic liquid crystal containing an optimal concentration of chiral substance into the cell.
While the molecules are arranged in a state with a twist angle in the range of 00° to 270°, at least one of the polarizing plates attached to the front and back of the cell has a function of absorbing a specific wavelength, and these polarization axes are Or the included angle of the absorption axis is 0° to 6
0°, and the included angle between the rubbing direction on the front substrate side and the polarization axis or absorption axis of both polarizing plates is 0° to 60', and the viewing angle dependence of contrast is It is possible to perform good display by reducing color unevenness, as well as having a small contrast ratio and a high contrast ratio.
Moreover, high display quality and high time division driving are also possible.

〔Example〕

1 to 3 show an embodiment of the present invention, in which transparent electrodes 3.4 and alignment layers 5, 6 are formed on the inward surfaces of two glass substrates 1, 2, and the required alignment After processing (described later), both substrates 1 and 2 are placed facing each other at a required minute interval, and their peripheral edges are adhered with a sealant 7 to form a cell, and a nematic liquid crystal 8 containing a chiral substance is injected into this cell. are doing. This liquid crystal 8 is formed on the front substrate 1 by an alignment process to be described later.
and the back substrate 2, resulting in a molecular arrangement having a twist angle within a range of 200° or more and 270° or less. Polarizing plates 9 and 10 are attached to the front and rear surfaces of the cell so that the included angle of the polarization axis (or absorption axis) and the included angle with the rubbing direction during alignment treatment have a predetermined relationship (described later). There is. Polarizing plates 9, 10
In this case, a polarizing plate having a function of absorbing a specific wavelength is used on one or both sides.

The specific wavelength is supertwisted
birefringence effect) is the wavelength of the background color of the cell.

The orientation treatment is performed as follows. That is, the alignment layer 5
, 6 so as to have a low tilt angle of 5" or less.The rubbing direction is from 10 degrees to 4 degrees from the upper left to the lower right on the front board l side with respect to the center line X, as shown in FIG.
The direction that makes an angle of 5 degrees (arrow bx), and the direction that makes an angle of 10 degrees or 45 degrees with respect to the center line In this case, the other directions are rotated by the required twist angle. As a result, the liquid crystal 8 has a molecular arrangement in which the liquid crystal 8 rotates to the left between the two difference plates 1 and 20 at a twist angle in the range of 200° to 270°.

- On the other hand, the polarizing plate 10 on the back side has a polarization axis (or absorption axis) C2 (FIGS. 1 and 2) and a rubbing direction (arrow 1) 1) in the alignment layer 5 on the inner surface of the front substrate 1. Paste it so that the included angle is from 00 to 60', and attach the polarizing plate 9 on the front side.
is pasted on the top 5 such that the included angle between its polarization axis (or absorption axis) cl (FIG. 2) and the polarization axis (or absorption axis) C2 of the polarizing plate 10 on the back side is from 00 to 60'.

The thickness d of the liquid crystal layer is determined by the product Δn-d of 0.8 μ? with the refractive index anisotropy Δn of the liquid crystal 8? The value is F1 to 1.0 μm. In addition, the chiral substance added to prevent intermediate state and reverse twist is 0.5 to 1.0% by weight (
pitch = 1 μm/10% by weight).

The liquid crystal display element having the above structure has a characteristic (Figure 6) that is a combination of the polarizing plate 9 or 100 spectral characteristic (Figure 4) and the spectral characteristic of light emitted by the SBK cell itself due to birefringence (Figure 5). Therefore, the background color will be achromatic. When an electric field is applied, a dark blue pattern is displayed on an achromatic background. This display has a vivid appearance and high display quality.

In addition, when the twist angle is less than 200', the contrast ratio is small, and when it is larger than 270°, it is difficult to prevent the occurrence of an intermediate state when aligning the alignment layer by normal rubbing. The range is from 200° to 270°.

〔Effect of the invention〕

As described above, according to the present invention, the twist angle of the liquid crystal between the side substrates is in the range of 200u to 270°, and the included angle between the rubbing direction on the front substrate side and the polarization axis or absorption axis of the polarizing plate, The angle between the polarization axes or absorption axes of the front and back polarizing plates is set in the range of 0° to 60', and a chiral substance is added at the optimum concentration to prevent the occurrence of intermediate state and reverse twist in the liquid crystal. When compared at the same duty ratio as a display element using 90'TN array cells, the dependence of the contrast on viewing angle is extremely small, the contrast ratio is small, and the contrast from the front is also good. Moreover, it has a wide viewing angle, and high time division driving is also possible. Also,
The thickness of the liquid crystal layer is such that Δn-a is 0.8 μm to 1.0 μm, so it is possible to display the best image quality, and the use of a polarizing plate that absorbs specific wavelengths allows for the achromatic background color.・It is possible to improve display quality by combining bright display colors and reducing color unevenness by combining different display colors. Furthermore, since it has an extremely low tilt angle of less than 5 degrees,
The desired orientation can be achieved by ordinary rubbing without requiring any special orientation treatment method.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing the rubbing directions of the front and rear substrates, the mutual polarization axes of the polarizing plates, and the relationships between the polarization axes of the polarizing plates and the rubbing directions in an embodiment of the liquid crystal display element according to the present invention. , FIG. 3 is a cross-sectional view of the same example, FIGS. 4 to 6 are spectral characteristic diagrams of the polarizing plate, SBK cell, and display element, and FIG. 7 is the rubbing direction of the front and back surfaces of the 9Q'TN array cell. It is an explanatory diagram showing a relationship. 1 and 2...Glass substrate 3 and 4...Transparent electrode 5 and 6...
Alignment layer 8...Liquid crystals 9 and 10 added with a chiral substance...Polarizing plate bl...Rubbing direction 132 on the front substrate side...
...Rubbing direction C1 on the rear substrate side Polarization axis C2 of the front polarizing plate Polarization axis of the back polarizing plate Patent applicant Stanley Electric Co., Ltd. Figure 6
Figure 7 Procedures for amendment October 1985/date

Claims (1)

[Claims] A transparent electrode and an alignment layer were formed on the inward facing surface, and an alignment treatment was performed by rubbing so that the tilt angle was 5° or less and the twist angle was in the range of 200° to 270°. The product Δn・d of the thickness d of the liquid crystal layer and the refractive index anisotropy Δn of the liquid crystal is 0.8 μm to 1.0 μm.
A cell is formed by making them face each other with a minute interval of μm and bonding their peripheral edges with a sealant, and injecting a nematic liquid crystal containing an optimal concentration of chiral substance into this cell.
While the molecules are arranged in a state with a twist angle in the range of 70°, at least one of the polarizing plates attached to the front and back of the cell has a function of absorbing a specific wavelength, and these polarization axes or absorption axes are A liquid crystal display characterized in that the included angle between the front substrate side and the rubbing direction of the front substrate side and the polarization axis or absorption axis of both polarizing plates is 0° to 60°. element.