JPS58127984A - Liquid crystal device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of a liquid crystal device that utilizes the electro-optic effect of liquid crystal, and more specifically to the improvement of the birefringence of liquid crystal molecules, that is, the birefringence of liquid crystal molecules, that is, the long axis direction of liquid crystal molecules and the direction orthogonal thereto. This invention relates to a liquid crystal device that utilizes the characteristics of light having different refractive indexes.

Recently, liquid crystal devices have been developed by applying the electro-optic effect exhibited by liquid crystals.)
It is often used as a display device for the 11 hour hand and numeric display panels on desks, etc., and is also used in fields other than display devices, such as optical shutters used in original image scanning units for photographic machines and printers, and in the field of optoelectronics. Applications are being developed.

However, using the electro-optic effect of conventional liquid crystal devices,
For example, when performing an optical shutter operation.

Orienting the liquid crystal in two directions to form a 9N and OFF state for light passage, or applying an electric field between opposing electrodes to forcibly change the alignment of the liquid crystal molecules interposed between the two electrodes. On the other hand, since the other method depends only on the initial liquid crystal molecular alignment, its response speed is extremely slow at several tens to hundreds of m5ee, and the speed of light is not perfect. The side bottom was not put to practical use as a party shutter.

Therefore, in order to improve the response speed of the conventional liquid crystal device, one of the opposing electrodes of the liquid crystal cell was made into a comb shape.
The electrode structure was proposed by Chanin.

A liquid crystal device using a liquid crystal cell with this three-electrode structure takes advantage of the retardation caused by the optical anisotropy of liquid crystal molecules. Liquid crystal cell l between polarizing plates Po and Mun
is the length direction of the comb-shaped electrode Lo%Lf1 of the liquid crystal cell 1 (
y-axis direction) is 4 with respect to the polarization axes of both polarizers Po and Mun.
It has a structure arranged with an inclination of 5″,
A voltage V is applied between the opposing electrodes LO and Ll of the liquid crystal cell 1.
When c is applied, the liquid crystal molecules are vertically aligned (two axes in the first direction) and the light passes through the liquid crystal cell as it is, so the light is blocked by two polarizing plates Po and Δn whose polarization axes are orthogonal to each other. At I, the light reaches the 01'F state, while the comb-shaped electrode is turned on.

When a voltage Vd is applied between and Ls, the liquid crystal molecules align in parallel (Fig. 1 (BJ) in the X-axis direction) and have the same optical characteristics as a uniaxial crystal with its optical axis in the X-axis direction.

Since the optical axis has an inclination of 45@ with respect to the two polarizing plates, the light passes with the intensity shown by the following equation, and the light becomes zero.

1 = 1o8in2248in8- In the formula, lO: Intensity of light after subtracting the loss when passing through polarizing plates Po and Munn φ: Angle between the polarization direction of the incident light and the liquid crystal molecule axis direction φ=45' δ : The phase difference between the ordinary ray and the extraordinary ray of the liquid crystal self, the light (DU N, LJ FF shape 1i
It is controlled by switching the application of the 1iat pressures Vc and va. In a liquid crystal device using a liquid crystal cell with this 31i polar structure, the alignment shift of the liquid crystal to form an ON, Ok'k' state for light passage is forced by the application of a voltage Vc% Vd, so the number of A fast response speed of m5eo can be obtained.

However, in a liquid crystal device using Chanin's liquid crystal cell with a three-electrode structure, each electrode of the liquid crystal cell has a fixed thickness, so that the direction of application of the electric field for aligning the liquid crystal is fixed. The top part of the electrode and the 11th part of the bulge are 42 and about 90'!
direction. Therefore, the passage of light t) k' F
When forming a state, the liquid crystal is oriented in the biaxial direction on the upper surface of the electrode LO, whereas in 1IilkU11b it is oriented in the X-axis direction and has the same optical properties as an l-axis crystal with the optical axis in the Therefore, the light beam has two polarizing plates and an angle of 45°. Therefore, only the lIi surface portion of the electrode always passes through the light having an intensity expressed by the same equation as when forming the ON-state excitation of light, and the ON-state of light is formed.

From the perspective of the electrode as a whole, it has the disadvantage that it is not possible to form an oFII' state in which light passes completely.

The present invention has been made to eliminate the above-mentioned conventional drawbacks, and its purpose is to provide a fast response speed and complete optical transmission.
The object of the present invention is to provide a liquid crystal device that can obtain an FF state and has an extremely high contrast ratio between ON and OK' states for light passage.

In the liquid crystal device of the present invention, a transparent substrate having an S-shaped electrode and a transparent substrate having a counter electrode are arranged close to each other between two polarizing plates whose polarization axes are perpendicular to each other so that both electrodes face each other, and both transparent A liquid crystal cell with liquid crystal sealed between substrates,
It is characterized in that the comb-shaped electrode is arranged parallel to the polarization axis of either one of the two polarizing plates.

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 (Δ1. (43)) shows the basic configuration of the liquid crystal device of the present invention, l is a liquid crystal cell, and m is a polarizing plate.

The liquid crystal cell l consists of a transparent substrate 2 having a comb-shaped electrode LO1L8 on its inner surface, and a transparent substrate 3 having a counter electrode L1 on its inner surface, which are arranged close to each other via a spacer 4 so as to form a predetermined gap between the two substrates. ! A liquid crystal 5 exhibiting positive dielectric anisotropy is sealed in the js.

The surfaces of the transparent substrates 2 and 30 are subjected to molecular alignment treatment to facilitate the alignment of 50 liquid crystal molecules.

The comb-shaped electrode 1. o, L2 and the counter electrode Ll are made of a transparent conductive material such as tin oxide or indium oxide.

It is formed by employing a conventionally well-known thin film method and etching method.

As shown in Fig. 113, the comb-shaped electrode has a shape in which a convex electrode L2 is fitted into a concave electrode LO, and the convex electrode L2 is grounded as a common electrode, and the concave electrode Lc> is connected as a drive electrode or a ground electrode to an external power source (not shown) or to a ground terminal by switching the switch 8.

Further, the counter electrode Lt is connected to an external power source (not shown) K as a control electrode.

When the concave electrode LO of the comb-shaped electrode is connected to the ground terminal by the switch 8, the comb-shaped electrode Lo%Li is all grounded, and a control voltage We is applied between the horizontal electrodes Lo, Lg and the counter electrode Ll. . By applying this control voltage We, the liquid crystal 5 is forcibly aligned in a direction perpendicular to the substrate 2.3 of the liquid crystal cell 1.

Furthermore, when the concave electrode Lo of the horizontal electrode is connected to the active power source, the driving voltage Va is applied between Lo and Lm of the Is-shaped electrode, and the control voltage ~C is applied between the counter electrode L1 and the comb-shaped electrode L3. By applying the driving voltage Vd and the control voltage Ve, the liquid crystal 5 is aligned in a direction resulting from the combination of the electric fields of both voltages, that is, in a diagonal direction with respect to the substrate 2° 3 of the liquid crystal cell 1.

Note that the number of teeth of the comb-shaped electrodes Lo and Lm is not limited to the three shown in FIG. 3, but can be arbitrarily changed depending on the size of the liquid crystal cell l. .

The polarized light &rO and mn are respectively arranged at the front and rear of the liquid crystal cell l, that is, on the light incident side and the light output side, and their polarization axes are orthogonal to each other. In addition, polarizing plate P
The polarizing axis of a is parallel to the comb-shaped electrode of the liquid crystal cell l, but instead of this, the polarizing plate m is parallel to its polarizing axis or the comb-shaped electrode of the liquid crystal cell l.
It is also possible to arrange the comb-shaped electrodes so that they are parallel to each other.

Thus, in the liquid crystal device of the present invention, a small lamp (not shown) having tungsten as a light emitting element is disposed as a light source in front of the polarizing plate Pa, and the 11 opposing poles Ls of the liquid crystal cell 1 are arranged as a light source.
When a control voltage VC is applied between the electrode LO1ld and the comb-shaped electrode LO1ld, the molecules of the liquid crystal 5 are oriented in a direction perpendicular to the substrate of the liquid crystal cell 1 (the Z-axis direction in FIG. 2 φ), and have a polarization axis in the y-axis direction. The light polarized in the y-axis direction by the polarizing plate klsc passes through the liquid crystal cell 1 as it is without being absorbed by the liquid crystal 5. The light in the y-axis direction passing through this liquid crystal cell l is
The light is completely absorbed and blocked by the polarizing plate Δn having the polarization axis in the axial direction, forming a (J F k'-like state) of light passing therethrough.

At this time, since each electrode of the liquid crystal cell l has a certain thickness, even if the liquid crystal located on the side surface of the electrode is aligned in the X-axis direction, the alignment direction will be different from that of the polarizing plate. Po
Since the direction is perpendicular to the polarization axis (y-axis direction) of
It is completely collected by the liquid crystal (liquid crystal aligned in the X-axis direction) and does not pass through the liquid crystal cell 1. Therefore, this liquid crystal device allows complete light to pass through even the side surfaces of the electrodes of the liquid crystal cell.
An FF state is formed.

In addition, the driving voltage V is applied to Lo and L2 of the comb-shaped electrode of the liquid crystal cell 1.
d, the control voltage ~C between the counter electrode L1 and the comb-shaped electrode LI
When the same voltage is applied, the molecules of the liquid crystal 5 are oriented obliquely to the substrate of the liquid crystal cell 1 (the axial direction resulting from the combination of the two axes in Figure 2 GB and the X axis), and the polarization axis is in the y-axis direction. A part of the light that is polarized in the y-axis direction by the polarizing plate Fo is rotated in the x-axis direction by the liquid crystal 5 and passes through the liquid crystal cell 1.

The light that has passed through this liquid crystal cell l and is rotated in the X-axis direction passes through a polarizing plate n that has a polarization axis in the X-axis direction,
An ON state for light passage is formed. This turns on the passage of light and puts it in the CUFF state.

Next, the effects of the present invention will be explained based on the following examples.

In the following example, the liquid crystal cell and the polarizing plate were arranged as shown in FIG. 2, and the Cζ horizontal electrode had the shape shown in FIG. 3. A 1ie-Ne laser (λ=6328K) is used as a light source, and a driving voltage of V is applied to each liquid crystal cell.
d and a control voltage Vc were applied, respectively, and the response speed (rise time and fall time) as a liquid crystal device, 0Δ of light passage, and the contrast ratio in the OFF state were measured.

Note that the rise time (Lwrite), fall time (1erase) and contrast ratio as response speeds are defined by the following equation.

Lyrics = [delay +[rtsaT+e
rase = [decay In the formula, [delay = rise time from the minimum value of the transmitted light intensity to 10% of the maximum value of the transmitted light intensity T/rise = from 10% to 90% of the maximum value of the transmitted light intensity 'Cdeeay = 90% of the maximum transmitted light intensity to 1
In the formula, l'max: Maximum value of transmitted light intensity 'l'mi
n: Minimum value of transmitted light intensity [Example 1] The liquid crystal cell and polarizing plate were rusted from the following, and the control voltage (35V (r*m, s)% as Vr) & drive voltage M
) asV (r, m, s) was applied to measure the response speed and the fundus thrust ratio.

M-crystal for liquid crystal cell & Result) Response speed rise time (T/write) = Q, 5 m5
e (1 fall time (TJdeeay) = 0.6 m5
6c contrast ratio [Example 2] Using the liquid crystal cell of Example 1 in which the gap between the transparent substrates (liquid crystal layer thickness) was 6.0 μm, the control voltage (Vc) was set to 60~(
r*m*s) & dynamic voltage (Vd) of 60V (r.

m, s) were applied, and the response speed and contrast ratio were measured in the same manner as in Example 1.

(Measurement results) Response speed rise time ('(write) = 0.25 m5
ec falling time (fidecay) = 0.5 m
! lee contrast ratio [Example 3] Example 1aJ A liquid crystal cell with a transparent substrate gap (liquid crystal layer thickness) of 6.0 μm was used, and the control voltage (Vc) was 8Q.
V (r, m, I), 80 as driving voltage (Vd)
V (r, m, s) was applied, and the response speed and contrast ratio were measured in the same manner as in Example 1.

(Measurement results) Response speed rise time (Zwrite) = 9.15 m5e
c Fall time (T/deoay) = 0.25 m
5ee contrast ratio [Comparative example] The liquid crystal cell of Example 1 and two polarizing plates were arranged as shown in Fig. 1, and the control voltage (Vc) was 35V (r*
'U-''), drive voltage (Va) of 35v (r
, m, s) were applied to measure the response speed and contrast ratio.

(Measurement results) Response speed rise time (T, write) = 1.5 rns
et3 fall time ('f/decay) = 9.3
5 m5se contrast ratio According to the liquid crystal device of the present invention, as can be seen from the measurement results of the above examples and comparative examples, the liquid crystal cell is placed between two polarizing plates whose polarization axes are orthogonal to each other, and the comb-shaped electrodes of the liquid crystal cell are By arranging the two polarizing plates so that they are parallel to the polarization axis of either one, the O
It is possible to obtain a liquid crystal device in which the contrast ratio between the NN state and the OFk state is dramatically improved, the response speed is extremely fast, and the fall time in particular is improved.

Note that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

Figure 1 Stop (Bl is a diagram for explaining the structure of a conventional liquid crystal device, Figure 2 GAI (B) is a diagram for explaining the structure of a liquid crystal device of the present invention, and Figure 3 is an example of a comb-shaped electrode. 1: Liquid crystal cell 2, 3: Transparent substrate 5: Liquid crystal LO1L8: Comb-shaped electrode Ll: Counter electrode Po, Δ
n: 81 polarizing plate patents Representative of Kyoto Ceramic Co., Ltd. S Morikazu Quiver Takao Mura Japanese Patent Publication No. 58-127984 (5)

Claims (1)

[Claims] Between two polarizing plates whose polarization axes are orthogonal to each other. A transparent substrate having a comb-shaped electrode and a transparent substrate having a counter electrode are arranged close to each other so that both electrodes face each other, and 1
A liquid crystal device characterized in that a liquid crystal cell having a liquid crystal sealed between both transparent substrates is arranged such that the horizontal electrode is parallel to the polarization axis of one of the two polarizing plates.