JPS63151924A - Electrooptical element - Google Patents

Abstract

PURPOSE:To obtain an electrooptical element showing hue similar to white as the hue of its appearance and showing hue similar to black as its appearance under a voltage-impressed state by arranging an optical anisotropic substance consisting of at least one layer between a pair of polarizing plates. CONSTITUTION:The titled element is provided with a liquid crystal cell constituted by holding twisted nematic liquid crystal between two opposed electrode bases and a pair of polarizing plates 1, 10 arranged on both the sides of the cell and 90-360 deg. twisting angle is obtained in the thickness direction of the element by adding an optically active substance to the nematic liquid crystal. At least one layer of the optical anisotropic substance in which nematic liquid crystal twisted in a direction different from the twisting direction of the liquid crystal in the cell is arranged between the pair of polarizing plates 1, 10. Consequently, an extremely excellent effect for turning the appearance of the electro- optical element to a color similar to white under the voltage-unimpressed state and to a color similar to black under the impressed state of a selected voltage can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electro-optical element, and particularly to an electro-optical element that has good time division drive characteristics in field effect mode.

[Conventional technology]

Conventional super rice dead nematic mode (hereinafter S
An electro-optical device that fully utilizes the TN mode (abbreviated as TN mode) has a twist angle of liquid crystal molecules of 9, as disclosed in Japanese Patent Application Laid-Open No. 60-50511
A pair of polarizing plates are provided below and below the liquid crystal cell, and the included angle between these polarization axes (absorption axes) and the molecular axis direction of the liquid crystal molecules adjacent to the electrode base is between 30 degrees and 60 degrees. Therefore, the external hue of the liquid crystal cell when no voltage is applied is blue instead of black.

Figure 3 shows the relationship between the directions of the polarization axis (absorption axis) of the liquid crystal cell and the polarizing plate of an electro-optical element using the conventional STN mode. In Figure 3, 22 is the rubbing of the upper electrode base of the liquid crystal cell. direction, 23 is the rubbing direction of the lower electrode base of the liquid crystal cell, 24 is the direction of the polarization axis (absorption axis) of the upper polarizing plate,
25 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 26 is the direction of the twist angle of the liquid crystal molecules of the liquid crystal cell and its angle (the twist is from top to bottom), and 27 is the rubbing direction of the lower electrode base. 22 is the angle formed by the direction 24 of the polarization axis (absorption axis) of the upper polarizing plate, and 28 is the angle formed by the rubbing direction 23 of the lower electrode substrate and the direction 25 of the polarization axis (absorption axis) of the lower polarizing plate. show.

In FIG. 3, angle 26 is approximately 210,111. angle 27
range from 40 degrees to 50 degrees, angle 28 from 40 degrees to 50 degrees
degree range, and the liquid crystal Δ6 * d f approximately 0.9μm
The spectrum t of the appearance of the electro-optical element when
Curve (2) shows that it is a spectrum when a selected voltage is applied by driving at a duty of 1/100.

[Problem that the invention seeks to solve]

In electro-optical elements using conventional BTM mode, it is not possible to make the external hue white, and hues ranging from green to yellow-red are psychologically difficult to accept as electro-optical elements. Furthermore, the hue upon application of the selection voltage was not black but blue, which was also not a desirable hue for an electro-optical element.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide at least one layer of optically anisotropic material between a pair of polarizing plates, thereby exhibiting a hue close to white in appearance; Another object of the present invention is to provide an electro-optical element that exhibits a hue close to black in appearance when a voltage is applied. Furthermore, with the aim of preventing deviations in hue characteristics due to temperature changes,
To make ΔR of the optical anisotropic body equal to Δ3 of the liquid crystal cell.

Furthermore, Δnd of the optical anisotropic body and Δndt of the liquid crystal cell
- By equalizing the contrast d! To provide an electro-optical element which always exhibits a hue close to black in appearance and further exhibits a hue close to white in appearance when a voltage is applied.

[Means for solving problems]

The electro-optical element of the present invention includes a liquid crystal cell formed by sandwiching twisted oriented nematic liquid crystal between two electrode substrates facing each other, a pair of polarizing plates disposed on both sides sandwiching the liquid crystal cell, and In an electro-optical element having a twist angle of more than 90 degrees and less than 360 degrees in the thickness direction of the element by adding an optically active substance to the nematic liquid crystal, at least one layer of optically anisotropic material is provided between the pair of polarizing plates. Characteristics [Implementation row] FIG. 1 is a top view of a cup of the present invention, which is shown as a rigging model of the pneumatic optical element. In the figure, 1 is a th: side polarizing plate, 2 is a liquid crystal cell as an optically anisotropic body (hereinafter referred to as the upper cell), 3 is the upper base of the upper cell, 4 is the lower base of the upper cell, and 5 is the liquid crystal of the upper cell, and 6 is the liquid crystal cell that performs display (
(Hereafter referred to as display cell).

7 is the upper electrode base of the display cell, 8 is the lower 01l of the display cell
11! A polar substrate, 9 a liquid crystal of a display cell, and 10 a lower polarizing plate. FIG. 2 is a diagram showing the relationship between the respective axes of the electro-optical element of the present invention. In the same figure, 11
12 is the rubbing direction of the lower electrode base of the display cell, and 12 is the rubbing direction of the lower electrode base of the display cell.

13 is the direction of the molecular axis of the liquid crystal molecules in the upper cell adjacent to the lower substrate of the upper cell, 14 is the direction of the molecular axis of the liquid crystal molecules in the upper cell adjacent to the upper substrate of the upper cell, and 15 is the lower polarized light. The direction of the polarization axis (absorption axis) of the plate, 16 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, 17 is the direction in which the liquid crystal molecules in the display cell are twisted downward from the soil, and the angle % 18 is the upward direction. The angle formed by the rubbing direction 12 of the north electrode substrate of the display cell with respect to the molecular axis direction 13 of the liquid crystal molecules in the upper cell adjacent to the lower substrate of the cell, 19 is the polarization axis (absorption axis) of the upper polarizing plate.
20 is the polarization of the lower polarizing plate with respect to the rubbing direction 11 of the lower electrode substrate of the display cell. Angle formed by direction 15 of axis (absorption axis), 21
indicates the direction and angle in which the liquid crystal molecules in the upper cell are twisted from top to bottom. Here, counterclockwise rotation is considered positive.

[Implementation same-l]

The structure of WIt is the same as that shown in FIG. Regarding the relationship shown in Figure 2, the twist angle 17 of the liquid crystal 9 of one display cell is approximately 21 to the left.
0 degrees and Δn-dk about 0.9 μm, and the twist angle 21 of the liquid crystal 5 of the upper liquid crystal cell is about 330 degrees to the right.
Δnod was set to about 05 μm on the right. Furthermore, the angle 18
'1i range from 80 degrees to 100 degrees, angle 19y! c-4
The range was 0 degrees to 150 degrees, and the angle was 20 degrees to 40 degrees to 50 degrees. The spectrum of the appearance of the electro-optical element at this time is shown in Fig. 5. In Fig. 5, curve I is the spectrum with no voltage applied, and curve ■ is the spectrum with the selective voltage applied by 1/100 chbty drive. As can be seen from FIG. 4, the appearance of the electro-optical element according to the prior art is yellow when no voltage is applied, and yellow when a selective voltage is applied.However, the electro-optical element of this embodiment As shown in FIG. 5, the appearance color is close to white when no voltage is applied, and close to black when one selection voltage is applied.

From the above, in Example 1, the appearance of the electro-optical element is improved by providing at least one layer of optically anisotropic material between the pair of polarizing plates placed on both sides of the liquid crystal cell. It was confirmed that when the voltage was applied, the color was close to white, and when the voltage was applied, the color was close to black.

〔fruit! Example M-2] The structure is the same as in FIG. 1. Regarding the relationship shown in FIG. 2, the twist angle 17 of the liquid crystal 9 of one display cell is 210 degrees to the left, and Δn·d is approximately 0.9 μm.

The twist angle of the liquid crystal 5 of the cell was 21t - 210 degrees to the right, and Δn*df was about 0.9 Am. Further, the angle 18 was set in the range from 80 degrees to 100 degrees, the angle 19'i was set in the range from 140 degrees to 150 degrees, and the angle 20' was set in the range from 40 degrees to 150 degrees. Spectrum t- of the appearance of the electro-optical element at this time
As shown in Fig. 6, curve I is the spectrum in the state where no voltage is applied, and curve 2 is the spectrum in the state in which the selected voltage is applied by 1/100d1Lty drive. The appearance of the electro-optical element is
When no voltage is applied, the color becomes yellow, and when a selected voltage is applied, it becomes blue. However, in the electro-optical element of the present invention, as shown in FIG. In the applied state, the external color becomes almost colorless,
Contrast is also sufficient.

From the above, in Example 2 of the present invention, when the twist angle of the liquid crystal of the display cell is 210° to the left, Δnod is about 0.9 μm, and when the twist angle of the liquid crystal of the h cell is 210° to the right, Δnod is about 0.9 μm.
m, an electro-optical element having at least one layer of optical anisotropy between a pair of polarizing plates disposed on both sides of the liquid crystal cell, and where i is Δnod of the liquid crystal cell.
By making ΔL-di of the optical anisotropic body equal to ΔL-di of the optical anisotropic body, the outer shell of the electro-optical element becomes a color close to white when no voltage is applied, and a color close to black when a selective voltage is applied, and the contrast is sufficient. I was able to confirm that.

[Example 3] The structure is the same as that shown in FIG. Regarding the relationship shown in Figure 2, the twist angle 17 of the liquid crystal 9 of one display cell is 120,1
50, 180, 240, 270 degrees, 300 degrees, and 330 degrees, and ΔnIId is approximately 0.9 μm. And the twist angle 21 of the liquid crystal 5 of the cell is set to the right 120-, corresponding to the display cell.
The angles were 150, 180, 240, 270, 300, and 330 degrees, and Δn·dk was approximately 0.9 μm. Furthermore, the angle 18
'e ranged from 80 degrees to 100 degrees, angle 19 ranged from 140 degrees to 150 degrees, and angle 20t ranged from 40 degrees to 50 degrees.The appearance of the electro-optical characteristics at this time is shown in Table 1.

As can be seen from FIG. 4, the appearance of the electro-optical element according to the prior art is yellow when no voltage is applied, and blue when a selective voltage is applied. As shown in Table 1, the appearance color is white when no voltage is applied, and close to black when one selection voltage is applied, and the contrast is sufficient.

Above), in implementation row-3, the twist angle of the liquid crystal of one display cell is 120.150.180.240 to the left.

270. ΔB*d is approximately 0.9 μm at 300 and 330 degrees,
and the twist angle of the liquid crystal of the cell is 120 to the right corresponding to the display cell.
, 150, 180, 240, 270, 300. In an electro-optical element in which Δnod is approximately 0.9 Am at 330 degrees, there is at least one layer of optical difference between a pair of polarizing plates placed on both sides of the liquid crystal cell. To celebrate the square,
Furthermore, Δnod of the liquid crystal cell and Δn@df% of the optical anisotropic body
By adjusting the electro-optical element, the appearance of the electro-optical element became close to white when no voltage was applied, and close to black when a color 1 selection voltage was applied, and it was confirmed that the contrast was sufficient.

Table 1 [Implementation row-4] The structure is the same as that in FIG. Regarding the relationship shown in FIG. 2, assuming that the twist angle 17 of the liquid crystal 9 of one display cell is 210 degrees to the left, Δn @ d is 0.5, 0.6, 0.7.

0.8, 1.0, 1.1, 1.2, 1.3μm
shall be. And the twist angle 21t of the liquid crystal 5 in the upper cell - right 2
1o0, and 0.5 corresponding to Δ7@adf display SE Ap
, 0.6 , 0.7, 0.8 , 1.0 , 1.1
, 1.2, and 1.3 μm.

Furthermore, the angle range is 18't80 degrees to 1001i.

Add 40 degrees to angle 19 in the range of 140 degrees to 150 degrees.
The range was from 50 degrees to 50 degrees. Table 2 shows the appearance of the electro-optical characteristics at this time.

As can be seen from Fig. 4, the appearance of the electro-optical element according to the prior art is yellow when no voltage is applied and blue when a selective voltage is applied. As shown in Fig. 2, the appearance color is close to white when no voltage is applied, and the appearance color is close to black when a selected voltage is applied, and the contrast is sufficient.

From the above, in implementation row-4, the twist angle of the liquid crystal of the display cell is 210 degrees to the left, and Δn ψd is 0.5 and 0.6.

0.7, 0.8, 1.0, 1.1, 1.2,
1.3 μmg Upper cell The twist angle of the upper cell is 210 degrees to the right and Δ
n@d corresponds to the display cell and is 0.5, 0.6, 0.
7, 0.8, 1.0, 1.1, 1.2, 1.3
In an electro-optical element such as Jim, at least one optically anisotropic material is provided between a pair of polarizing plates placed on both sides of a liquid crystal cell, and further, the Δ of the liquid crystal cell is
By making n@d equal to Δn-df of the optically anisotropic body, the appearance of the electro-optical element becomes close to white when no voltage is applied, and close to black when a selective voltage is applied.

It was confirmed that the contrast was also sufficient.

Table 2 [Implementation row-5] The structure is the same as in FIG. Regarding the relationship shown in FIG. 2, it is assumed that the twist angle 17 of the liquid crystal 9 of the cell shown in Table 1 is 210 degrees to the left and dt-6Am. and.

The twist angle 21 of the liquid crystal 5 in the upper cell is 210 degrees to the right, dt″6
It was set as μm. Also, △n = 0.1 in 1 display cell, upper cell
5 liquid crystals were sealed. Furthermore, angle 18'i ranges from 80 degrees to 100 degrees, angle 19'! 5-40 degrees to 150 degrees
The angle ranged from 20t-40 degrees to 50 degrees. Table 3 shows the relationship between the temperature and the appearance of the custom-made electro-optic.

Table 3 As can be seen from FIG. 4, the appearance of the electro-optical element according to the prior art is yellow when no voltage is applied, and blue when a selective voltage is applied.However, in the electro-optical element of the present invention, As shown in , a degree is 1υ℃~50'
There is no change in appearance between C and C, and the appearance color is close to white when no voltage is applied, and close to black when one selection voltage is applied, and the contrast is sufficient.

From the above, in row-5, the twist angle of the liquid crystal in one display cell is 210 degrees to the left and d is 6 μm, and the twist angle of the liquid crystal in the upper cell is 210 degrees to the right and d is 6 μm.
In an electro-optical element in which n is equal to 0.15, at least one layer of optically anisotropic material t- is provided between a pair of polarizing plates placed on both sides of the liquid crystal cell, and d of the liquid crystal cell and optically The appearance of the electro-optical element is at least 10°C to 50°C by making sure that the d of the anisotropic body is equal and completely filling the liquid crystal cell with Δn equal to that of the liquid crystal cell and the optically anisotropic body.
Between 'C, always 1! When no pressure is applied, the color is close to white.

When the selective voltage was applied, the color became close to black, and it was confirmed that the contrast was sufficient.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a liquid crystal cell in which twistedly oriented ematic liquid crystal is sandwiched between two electrode substrates facing each other, and a pair of polarizing plates disposed on both sides sandwiching the liquid crystal cell. By adding an optically active substance to the nematic liquid crystal, it is possible to increase the angle by 90 degrees in the thickness direction of the device.
In an electro-optical element having a twist angle of less than 0 degrees, an optically anisotropic body having at least one layer of nematic liquid crystal twisted in a direction different from the twist direction of the liquid crystal in a liquid crystal cell is enclosed between a pair of polarizing plates.

An extremely excellent effect can be obtained in that the appearance of the electro-optical element becomes a color close to white when no voltage is applied, and a color close to black when a selective voltage is applied.

Furthermore, by aligning the liquid crystal cell and the liquid crystal of the optically anisotropic body in all different directions of twist, the appearance of the electro-optical element can be changed to a color that is close to white when no voltage is applied, and when a selected voltage is applied. The effect is that the color becomes close to black and the contrast is sufficient.

Also, the dt of the liquid crystal cell and the optically anisotropic body are equal.

By enclosing liquid crystals with the same Δn, at least l
Between 0°C and 50'C, there is no change in the appearance of the electro-optical element due to temperature, and the color is always close to white in the voltage application state, and the color is close to black in the 1 selection voltage application state, and the contrast is sufficient. You can get the effect that there is.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating the structure of the electro-optical element of the present invention as a model, FIG. 2 is a diagram showing the relationship between the axes of the electro-optical element of the present invention, and FIG. 3 is an electro-optic according to the prior art. FIG. 4 is a diagram showing the relationship between the respective axes of the element, FIG. 4 is a diagram showing the relationship between external wavelength and transmittance characteristics of an electro-optical element according to the prior art, and FIG. 5 is an electro-optical element according to embodiment row-1 of the present invention. FIG. 6 is a diagram showing the relationship between the wavelength of the external appearance of the element and the transmittance characteristic; FIG. l... Upper polarizing plate 2 -... Liquid crystal cell as an optically anisotropic body (upper cell) Book 3... Upper base of upper cell 4, fist, lower base of upper cell 5... of 1 cell Liquid crystal 6...Liquid crystal cell (display cell) that performs display 7...Upper electrode base of display cell 8...Lower electrode base of display cell 9...Liquid crystal 10 of display cell...°...lower side Polarizing plate 11 -- Rubbing direction of the lower electrode base of the display cell 12 -- Rubbing direction of the upper electrode base of the display cell 13 -- Molecules of liquid crystal molecules in the upper cell adjacent to the lower base of the upper cell The direction of the axis 14... and the direction of the molecular axis of the liquid crystal molecules in the upper cell adjacent to the upper substrate of the cell 15... The direction of the polarization axis (absorption axis) of the lower polarizing plate 16.
... Direction of the polarization axis (absorption axis) of the upper polarizing plate 17 ... The direction in which the liquid crystal molecules in the display cell are twisted from top to bottom and its angle 18 ... Angle 19 formed by direction 12 with respect to direction 13・
...The angle formed by the direction 14 with respect to the direction 16...The angle 21 @ formed by the direction 15 with respect to the direction 11...The direction in which the liquid crystal molecules in the cell are twisted from top to bottom and the angle thereof...Liquid crystal Rubbing direction of the upper electrode base of the cell...Rubbing direction of the lower electrode base of the liquid crystal cell...Direction δ of the polarization axis (absorption axis) of the upper polarizing plate...
The direction of the polarization axis (absorption axis) of the lower polarizing plate...The direction of the twist angle of the liquid crystal molecules of the liquid crystal cell and its angle n...The rubbing direction n of the upper electrode base and the polarization axis (absorption axis) of the upper polarizing plate. axis) direction 2! Angle between the rubbing direction wing of the lower electrode substrate and direction 5 of the polarization axis (absorption axis) of the lower polarizing plate. Applicant: Seiko Epson Co., Ltd. Agent, Attorney Mogami Tsutomu and 1 other person: ==::=:=====Qi 1 □10 Figure 1 Figure 71 (%) Figure 1

Claims (4)

[Claims] (1) A liquid crystal cell consisting of a twistedly oriented nematic liquid crystal sandwiched between two opposing electrode substrates, and a pair of polarizing plates placed on both sides sandwiching the liquid crystal cell, the nematic liquid crystal has optical rotation. An air optical element having a twist angle of more than 90 degrees and less than 360 degrees in the thickness direction of the element by adding a substance, characterized in that at least one layer of optically anisotropic material is provided between the pair of polarizing plates. electro-optical element. (2) The electricity according to claim 1, characterized in that the product Δn·d of the refractive index anisotropy Δn of the optically anisotropic body and the layer thickness d is equal to Δn·d of the liquid crystal cell. optical element. (3) Claim 1, wherein the optically anisotropic body is made of nematic liquid crystal, and the twist angle of the nematic liquid crystal is approximately equal to that of the nematic liquid crystal in the liquid crystal cell, and the twist directions are different. The electro-optical element according to item 1 or 2. (4) The electro-optical element according to claim 1 or 3, wherein the refractive index anisotropy of the optically anisotropic body and the refractive index anisotropy of the liquid crystal cell are equal.