JP3285402B2 - Antiferroelectric liquid crystal panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiferroelectric liquid crystal panel such as a liquid crystal display panel having a matrix of pixels and a liquid crystal optical shutter array using an antiferroelectric liquid crystal as a liquid crystal layer.

[0002]

2. Description of the Related Art A liquid crystal panel using an antiferroelectric liquid crystal,
Japanese Patent Application Laid-Open No. 2 by Nippondenso Co., Ltd. and Showa Shell Sekiyu KK
173724 discloses that it has a wide viewing angle, high-speed response, good multiplex characteristics, etc., and has been vigorously studied.

FIG. 2 is a conventional configuration diagram when an antiferroelectric liquid crystal is used as a display. The liquid crystal cell 22 is placed between the polarizing plates 21a and 21b adjusted to cross Nicol such that the polarization axis of one of the polarizing plates and the long axis direction of the liquid crystal molecules when no voltage is applied are parallel. Sometimes black can be displayed and white can be displayed when an electric field is applied.
In such a cell configuration, when a voltage is applied to the liquid crystal cell, a change in transmittance with respect to the voltage is plotted on a graph, whereby a hysteresis curve as shown in FIG. 3 can be drawn. From FIG. 3, it can be seen from FIG. 3 that when a certain pulse wave is applied to the liquid crystal molecules, the transmittance is saturated when the product of the pulse width and the voltage value exceeds a threshold value, that is, the first state is reached. Is selected (ferroelectric state). When a pulse wave having a polarity opposite to that of the applied voltage is applied and the value is equal to or larger than the threshold value, the transmittance is saturated, that is, the second stable state (ferroelectric state) is selected. From the first state and the second state, if the absolute value of the product of the pulse width and the voltage value is lower than a certain threshold, a third stable state (antiferroelectric state) is selected. .

[0004]

However, in general, the direction of the long axis of the liquid crystal molecules when no voltage is applied (third stable state) and the long axis of the liquid crystal molecules in the first stable state where the transmittance is saturated are generally formed. The angle may not be equal to the angle formed by the liquid crystal molecule long axis direction in the second stable state where the transmittance is saturated by applying a voltage of the opposite polarity to the liquid crystal molecule long axis direction when no voltage is applied. Therefore, when the polarizing plate and the liquid crystal cell are configured such that the long axis direction of the liquid crystal molecules when no voltage is applied and one of the polarizing axis directions of the polarizing plate are in a parallel state as in the related art, the first Since the angle between the long axis direction of the molecule in the stable state and the polarization axis direction is different from the angle between the long axis direction of the second stable state and the polarization axis direction, the transmittance of light in the first stable state And the light transmittance in the second stable state is also different. For this reason, the light transmittance differs between the case where white display is performed in the first stable state and the case where white display is performed in the second stable state, and visually different white is displayed. In some cases, it is seen as flicker. Therefore, an object of the present invention is to provide a good display with less flickering regardless of what kind of antiferroelectric liquid crystal material is used.

[0005]

According to the present invention, there is provided a liquid crystal panel having an antiferroelectric liquid crystal interposed therebetween, wherein two liquid crystal panels are provided such that their polarization axes are orthogonal to each other. The polarization axis direction of one of the polarizing plates was sandwiched between the plates, and the voltage change of the transmittance was saturated by applying a voltage of the opposite polarity to the molecular long axis direction when the transmittance change was saturated by applying the liquid crystal panel voltage. In such a case, the angle may be parallel to half the angle between the
Both the polarization direction of the molecule and the polarization direction of the two polarizing plates when no pressure is applied
The anti-ferroelectric liquid crystal molecules are configured so as not to coincide with the optical axis direction , so that the antiferroelectric liquid crystal molecules in the molecular long axis direction in a stable state when no voltage is applied and in the molecular long axis direction in a first stable state when a voltage is applied. Even when the angle between the direction and the direction of the long axis of the molecule in the second stable state is different, the angle between the direction of the polarization axis of the polarizing plate and the direction of the long axis of the molecule in the first stable state, Is characterized by that the angle formed by the long axis direction of the molecule in the stable state is the same.

[0006]

When the display is performed by the antiferroelectric liquid crystal, it is necessary to use both the first stable state and the second stable state when performing the white display so as not to leave the DC component of the applied voltage. For this reason, when the transmittances are different from each other, when an actual display is performed, the display is viewed as a flicker, and a good display cannot be performed.

However, when the direction of the polarization axis of the polarizing plate is made to coincide with half the angle between the long axis direction of the molecule in the first stable state and the long axis direction of the second molecule. The angle between the direction of the long axis of the molecule in the first stable state and the polarization axis;
Since the angle between the long axis direction of the molecule in the second stable state and the polarization axis is equal, the transmittance of light in the first stable state is equal to the transmittance of light in the second stable state. Even when display is performed, good display can be performed without flicker.

[0008]

(Embodiments) Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 4 is a cell configuration diagram of the liquid crystal panel used in this embodiment. The liquid crystal panel used in this embodiment includes a pair of glass substrates 43a and 43b having an antiferroelectric liquid crystal layer 46 having a thickness of about 2 μm. Electrodes 44a and 44b are formed on the opposite surface of the glass substrate, and polymer alignment films 45a and 45b are applied thereon, and rubbing is performed. Further, a first polarizing plate 41a is provided outside one of the glass substrates, and a polarizing axis of the second polarizing plate 41b is 90 ° outside of the other glass substrate with respect to the polarizing axis of the first polarizing plate 41a. The second polarizing plate 41b is installed so as to be different. As shown in FIG. 1, the polarization axis 13b of the first polarizing plate 11b is applied with a reverse voltage by applying a voltage and applying a reverse voltage to the liquid crystal molecule long axis direction when the transmittance is saturated (first stable state). When the transmittance was saturated (second stable state), the angle was set to be parallel to an angle direction which was の of the angle formed with the long axis direction of the liquid crystal molecules. At this time, the molecular major axis direction when no voltage was applied was inclined by 4 ° with respect to the polarization axis 13b. As a result, the transmittance of the liquid crystal cell in the first stable state in which the change in transmittance is saturated by applying a voltage is 36.6%, and the transmittance in the second stable state in which the change in transmittance is saturated by applying a voltage having the opposite characteristic. The transmittance was also equal to 36.6%, and good display could be performed without flickering even when display was performed by time-division driving.

Comparative Example Using the same cell configuration as in FIG. 4 as in the embodiment, the first polarizing plate 41a is provided outside the glass substrate as in the embodiment, and the other glass substrate is The second polarizing plate 41b is provided so as to be different from the polarizing axis of the first polarizing plate 41a by 90 °. However, as shown in FIG. 2, the polarization axis 23a of one of the polarizing plates 21a was set to be parallel to the major axis direction of the liquid crystal molecules when no voltage was applied. As a result, when the voltage is applied and the transmittance change is saturated, the first
The transmittance of the liquid crystal cell in the stable state is 37.8%, and the transmittance in the second stable state in which the change in transmittance is saturated by applying a voltage having the opposite characteristic is 35.8%, and the same white display is performed. When the display was performed, the transmittance was different, and it was visually recognized as flickering.

Table 1 shows the results of Examples and Comparative Examples.

[0011]

[0012]

As described in the above embodiments, by using the cell structure of the present invention, a good time-division driving display without flicker can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a liquid crystal cell and a polarizing plate used in the present invention.

FIG. 2 is a configuration diagram of a conventional antiferroelectric liquid crystal cell and a polarizing plate.

FIG. 3 is a diagram showing a hysteresis curve showing characteristics of an antiferroelectric liquid crystal.

FIG. 4 is a diagram showing a cell configuration of an antiferroelectric liquid crystal panel.

[Explanation of symbols]

 11a, 11b Polarizer 12 Liquid crystal cell 21a, 21b Polarizer 22 Liquid crystal cell 41a, 41b Polarizer 42a, 42b Sealant 43a 43b Glass substrate 44a, 44b Electrode 45a, 45b Polymer orientation film 46 Antiferroelectric liquid crystal

Claims (1)

(57) [Claims] An antiferroelectric liquid crystal is sandwiched between a pair of substrates, wherein the antiferroelectric liquid crystal is in a first stable state when a voltage is applied, and when an antipolar voltage is applied. It has a second stable state and a third stable state when a voltage lower than the threshold is applied.
An antiferroelectric liquid crystal in which the angle between the liquid crystal molecule long axis direction in the stable state and the liquid crystal molecule long axis direction in the second stable state is different from the angle formed between the third stable liquid crystal molecule long axis direction A panel, wherein the antiferroelectric liquid crystal panel includes two polarizing plates, and directions of polarization axes of the two polarizing plates are mutually opposite.
Orthogonal to have further to the first liquid crystal molecular long axis direction of the steady state and 1/2 of the angular direction of the angle between the liquid crystal molecular long axis direction of the second stable state, among the two sheets of polarizing plates An anti-ferroelectric liquid crystal panel characterized in that one polarizing plate has its polarization axis direction set.