JP2000338489A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give wide viewing angle characteristic. SOLUTION: The device is equipped with a liquid crystal layer 5A for a display in which liquid crystal molecules are aligned in a specified aligned state, display controlling electrodes 7, 8 to apply an electric field on the liquid crystal layer 5A for the display, and a pair of optical compensation layers 10a, 10b disposed to interpose the liquid crystal layer 5A for the display. The optical compensation layers 10a, 10b are formed from a discotic liquid crystal, and the discotic liquid crystal molecules 11 are aligned as lodging in an almost horizontal direction on one of the face opposing the liquid crystal layer 5A for the display and the opposite face, and aligned as standing almost perpendicular to the other face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art In general, a liquid crystal display element is provided with a liquid crystal layer in a region surrounded by a sealant between a pair of substrates joined via a frame-like sealant, and provided on an inner surface of the pair of substrates. Each is provided with a display control electrode for applying an electric field to the liquid crystal layer, and an alignment film for aligning liquid crystal molecules in a predetermined alignment state thereon.

The above-mentioned liquid crystal display devices include those using a nematic liquid crystal and those using a ferroelectric or antiferroelectric liquid crystal. In the liquid crystal display device using a nematic liquid crystal, liquid crystal molecules are twist-oriented. The liquid crystal molecules are homeotropically aligned, the liquid crystal molecules are homeotropically aligned, and the liquid crystal molecules are hybridized.

[0004] These liquid crystal display elements generally have a pair of polarizing plates on both surfaces thereof. The liquid crystal display element has a birefringence effect of liquid crystal in accordance with an alignment state of liquid crystal molecules which changes according to an electric field applied to the liquid crystal layer. The transmission of light is controlled and displayed by the polarizing action of the polarizing plate.

[0005] The liquid crystal display element has a reflection plate on the back surface thereof for displaying by using external light, and a liquid crystal display element using a backlight and a display using illumination light from the backlight. Some of the reflective liquid crystal display elements include a single polarizing plate only on the front surface thereof.

[0006]

The display characteristics (electro-optical characteristics) of the liquid crystal display element are determined by the birefringence Δ of the liquid crystal layer.
Determined by the value of the product Δnd of n and the thickness d of the liquid crystal layer, the birefringence Δn of the liquid crystal layer changes according to the change in the alignment state of the liquid crystal molecules due to the electric field applied to the liquid crystal layer.

However, the alignment state of the liquid crystal molecules of the liquid crystal layer is regulated by the alignment films provided on the inner surfaces of the pair of substrates. However, the liquid crystal molecules in the surface layer of the liquid crystal layer, that is, in the vicinity of the substrate which is strongly subjected to the alignment regulating force by the alignment film, hardly change the alignment state even when an electric field is applied.

That is, in a liquid crystal display device such as a TN (twisted nematic) type or STN (super twisted nematic) type in which liquid crystal molecules are twisted, the liquid crystal molecules are affected by an applied electric field. Accordingly, the liquid crystal molecules are aligned so as to rise with respect to the substrate surface while maintaining the twist alignment state, but the liquid crystal molecules in the vicinity of the substrate lie down at a pretilt angle or an angle close to the pretilt angle with respect to the substrate surface even when an electric field is applied. It remains in a state.

For example, in a liquid crystal display device in which liquid crystal molecules are homeotropically aligned, the liquid crystal molecules are oriented so as to fall from the initial homeotropic alignment state to the substrate surface in accordance with an applied electric field. However, even when an electric field is applied, the liquid crystal molecules in the vicinity of the substrate are not aligned horizontally with respect to the substrate surface.

For this reason, the change in the birefringence Δn of the liquid crystal layer when an electric field is applied to the liquid crystal layer is not uniform over the entire thickness of the liquid crystal layer.
The difference in the birefringence Δn affects the display characteristics of the liquid crystal display device.

The effect on the display characteristics that the liquid crystal molecules in the surface portion of the liquid crystal layer hardly change from the initial alignment state is as follows when the display is viewed from the front of the screen (near the direction perpendicular to the screen). Although it is almost inconspicuous, when viewed from an oblique direction, the display contrast is greatly reduced. Therefore, the liquid crystal display element has a problem that a viewing angle at which a display can be observed with good contrast is narrow.

For this reason, conventionally, the display characteristics due to the difference in the birefringence Δn between the center portion of the liquid crystal layer thickness and the surface layer portion caused by the fact that the liquid crystal molecules in the surface layer portion of the liquid crystal layer hardly change from the initial alignment state. It has been considered that the influence of the above is compensated for by the phase difference plate to widen the viewing angle.

However, such viewing angle compensation using a retardation plate can only improve the viewing angle in one direction determined by the direction of the optical axis (slow axis or fast axis) of the phase difference plate. .

According to the present invention, the influence on the display characteristics due to the fact that the liquid crystal molecules in the surface portion of the liquid crystal layer hardly change from the initial alignment state can be compensated over a wide range of directions, and the viewing angle can be widened. It is intended to provide a liquid crystal display element.

[0015]

According to the present invention, there is provided a liquid crystal display device comprising: a display liquid crystal layer in which liquid crystal molecules are aligned in a predetermined alignment state; and a display control electrode for applying an electric field to the display liquid crystal layer. An optical compensation layer provided on at least one surface side of the display liquid crystal layer, wherein the optical compensation layer is made of a discotic liquid crystal, and the discotic liquid crystal molecules face the display liquid crystal layer. In this case, one of the surface and the opposite surface is oriented horizontally in a horizontal direction, and the other surface is oriented substantially vertically in an upright orientation.

That is, in the liquid crystal display device of the present invention, the display state is controlled by controlling the alignment state of the liquid crystal molecules in the display liquid crystal layer by applying an electric field, and the liquid crystal molecules in the surface layer portion of the display liquid crystal layer are in the initial state. The effect on the display characteristics due to little change from the alignment state is compensated by the optical compensation layer made of the discotic liquid crystal.

In the optical compensation layer, the discotic liquid crystal molecules are oriented in a horizontal orientation on one of the surface facing the display liquid crystal layer and the opposite surface, and substantially perpendicularly on the other surface. Since the liquid crystal molecules are discotic liquid crystal, the alignment state of the discotic liquid crystal molecules and the alignment state of the liquid crystal molecules in the display liquid crystal layer are opposite to each other. There is no.

Therefore, according to this liquid crystal display device, the liquid crystal molecules in the surface layer of the display liquid crystal layer hardly change from the initial alignment state and the center of the liquid crystal layer thickness of the display liquid crystal layer and the surface layer of the display liquid crystal layer. The influence on the display characteristics due to the difference in the birefringence Δn between the portions can be compensated over a wide range of directions by the optical compensation layer made of the discotic liquid crystal, and the viewing angle can be widened.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, a liquid crystal display device according to the present invention comprises a display liquid crystal layer in which liquid crystal molecules are aligned in a predetermined alignment state, and a display control for applying an electric field to the display liquid crystal layer. Electrode, and an optical compensation layer provided on at least one surface side of the display liquid crystal layer, wherein the optical compensation layer is made of a discotic liquid crystal, and the discotic liquid crystal molecules are formed of the display liquid crystal. The liquid crystal layer for display is characterized in that the liquid crystal layer for display is substantially horizontally oriented in a falling direction on one surface of a surface facing the layer and a surface opposite to the layer, and is vertically oriented on the other surface. Can compensate for the influence on the display characteristics due to the fact that the liquid crystal molecules in the surface layer portion hardly change from the initial alignment state, and can widen the viewing angle over a wide range of orientations.

In the liquid crystal display device according to the present invention, when the display liquid crystal layer is provided between a pair of alignment films having the same alignment of either horizontal alignment or vertical alignment, A pair of optical compensation layers composed of the discotic liquid crystal may be disposed with the surfaces having the same orientation state of the discotic liquid crystal molecules facing each other, with the liquid crystal layer interposed therebetween. The pair of optical compensation layers compensates for the effect on display characteristics caused by the fact that the liquid crystal molecules on the surface layer on one surface and the other surface of the display liquid crystal layer hardly change from the initial alignment state, and provides a wide field of view. The corners can be widened.

The discotic liquid crystal used for the optical compensation layer may be a discotic liquid crystal exhibiting a liquid crystal phase at room temperature or a discotic polymer liquid crystal. The optical compensation layer may be formed of a discotic liquid crystal exhibiting a liquid crystal phase at room temperature. If an optical compensation adjustment electrode for controlling the alignment state of the discotic liquid crystal is provided with the optical compensation layer interposed therebetween, the voltage applied between the optical compensation adjustment electrodes is controlled to control the voltage. The alignment state of the discotic liquid crystal molecules can be changed, and therefore, the retardation of the optical compensation layer is adjusted according to the electric field applied to the display liquid crystal layer, and the liquid crystal molecules in the surface layer of the display liquid crystal layer are adjusted. Can be more effectively compensated for the effect on display characteristics due to little change from the initial alignment state. That.

If the optical compensation layer is formed of a discotic polymer liquid crystal, the optical compensation layer can be handled as a solid, so that the structure of the liquid crystal display device is simplified and its thickness is reduced. be able to.

[0023]

1 is a sectional view of a part of a liquid crystal display device according to a first embodiment of the present invention.
A display liquid crystal layer 5A in which liquid crystal molecules are aligned in a predetermined alignment state between a pair of front and rear transparent substrates 1 and 2 made of glass or the like;
Transparent display control electrodes 7 and 8 for applying an electric field to the display liquid crystal layer 5A, and a pair of optical compensation layers 10a and 10b disposed with the display liquid crystal layer 5A interposed therebetween; In this configuration, a pair of polarizing plates 16 and 17 are arranged on the outer surfaces of the pair of substrates 1 and 2, respectively.

Of the display liquid crystal layer 5A and the pair of optical compensation layers 10a and 10b, the display liquid crystal layer 5A is formed of a pair of transparent resin films disposed on the inner surfaces of the pair of substrates 1 and 2, respectively. Between the inner substrates 3 and 4.

Each of the pair of inner substrates 3 and 4 is joined to the pair of front and rear substrates 1 and 2 at the peripheral edge thereof via a frame-shaped sealing material (not shown). Inner substrates 3 and 4 are joined at their peripheral edges via a second frame-shaped sealing material (not shown).

The display control electrodes 7 and 8 are formed on the inner surfaces of the pair of inner substrates 3 and 4, respectively. The display control electrodes 7 and 8 are formed on the inner surfaces of the inner substrates 3 and 4 respectively. , 8 are provided with an alignment film 9a.

The liquid crystal display device of this embodiment is of the active matrix type, and the display control electrodes 8 provided on the inner surface of one of the pair of inner substrates 3 and 4 are arranged in the row direction. The plurality of pixel electrodes arranged in the column direction and the display control electrode 7 provided on the inner surface of the other substrate 3 are a single-film counter electrode facing the plurality of pixel electrodes 8.

Although not shown in the figure, a plurality of TFTs (thin film transistors) connected to the plurality of pixel electrodes 8 and a plurality of TFTs (rows) are provided on the inner surface of the inner substrate 4 on which the pixel electrodes 8 are formed. A plurality of gate lines for supplying gate signals to the TFTs and a plurality of data lines for supplying data signals to the TFTs in each column are provided, and the alignment film 9a is formed so as to cover these. ing.

The liquid crystal display device of this embodiment has a TN
(Twisted nematic) type, wherein the display liquid crystal layer 5A is made of a nematic liquid crystal having a positive dielectric anisotropy in which liquid crystal molecules 5a are twist-aligned, and the pair of polarizing plates 16 and 17 are respectively provided. The optical axis (transmission axis or absorption axis) is arranged in a predetermined direction.

That is, each of the alignment films 9a provided on the inner surfaces of the pair of inner substrates 3 and 4 is a horizontal alignment film having a horizontal alignment property, which has been subjected to an alignment treatment in a predetermined direction. Liquid crystal molecules 5a of the display liquid crystal layer 5A
Are formed by the horizontal alignment film 9a.
The orientation direction in the vicinity of the substrate 4 is regulated, and the twist orientation is performed at a twist angle of about 90 between the inner substrates 3 and 4.

Although FIG. 1 schematically shows the alignment state of the liquid crystal molecules 5a of the display liquid crystal layer 5A, the liquid crystal molecules 5a have a slight pretilt angle with respect to the inner substrates 3 and 4. It is twist-oriented in a laid state.

On the other hand, a pair of optical compensation layers 10a and 10b arranged with the display liquid crystal layer 5A interposed therebetween, respectively.
It is made of a discotic liquid crystal (a liquid crystal having a molecular shape of a disc) exhibiting a liquid crystal phase at room temperature, and the discotic liquid crystal forming the optical compensation layer 10a on the front side is the front substrate 1 of the pair of substrates 1 and 2. And a discotic liquid crystal that is provided between the inner substrate 3 disposed therein and forms the rear optical compensation layer 10a includes the rear substrate 2 of the pair of substrates 1 and 2, It is provided between the inside substrate 4 disposed inside.

Further, the opposing surfaces of the front substrate 1 and the inner substrate 3 which face each other with the front optical compensation layer (discotic liquid crystal layer) 10a therebetween, and the rear optical compensation layer (discotic liquid crystal layer) On the opposing surfaces of the rear substrate 2 and the inner substrate 4 that face each other with the 10b interposed therebetween, a single-film-shaped transparent optical compensation adjustment electrode 12 for controlling the alignment state of the discotic liquid crystal is provided. 13
And alignment films 14 and 15 for regulating the initial alignment state of the discotic liquid crystal molecules 11 are formed on these electrodes 12 and 13.

One of the alignment films 14 and 15 is a horizontal alignment film having a horizontal alignment, and the other alignment film is a vertical alignment film having a vertical alignment. The molecules 11 of the discotic liquid crystal forming the liquid crystal layer 10b are oriented substantially horizontally in one of the surface facing the display liquid crystal layer 5A and the opposite surface, and rise substantially vertically in the other surface. Oriented.

The liquid crystal display element of this embodiment is of the TN type, and the display liquid crystal layer 5A is provided between a pair of horizontal alignment films 9a. A pair of optical compensation layers 10a and 10b made of the discotic liquid crystal are disposed with the surfaces of the discotic liquid crystal molecules 11 having the same alignment state facing each other with the liquid crystal layer 5A interposed therebetween.

That is, in this embodiment, of the pair of alignment films 14 and 15 sandwiching the optical compensation layers 10a and 10b, the alignment film 15 on the side facing the display liquid crystal layer 5A.
Is a horizontal alignment film, and the alignment film 14 on the opposite side is a vertical alignment film.
As shown in FIG. 1, each of the discotic liquid crystal molecules 11b is oriented substantially horizontally on the surface opposed to the display liquid crystal layer 5A, and substantially vertically rises on the surface opposite to the display liquid crystal layer 5A. The liquid crystal layer 5A is oriented so as to gradually rise vertically from the lying state from the surface facing the liquid crystal layer 5A to the surface on the opposite side.

The vertical alignment film 14 of the pair of alignment films 14 and 15 sandwiching the optical compensation layers 10a and 10b is subjected to an alignment treatment for controlling the rising alignment state of the discotic liquid crystal molecules 11. The discotic liquid crystal molecules 11 of the optical compensation layer 10a on the front side are:
On the surface opposite to the display liquid crystal layer 5A, the molecular axis perpendicular to the disk-shaped molecular surface is aligned with the alignment direction of the liquid crystal molecules 6a on the front side of the display liquid crystal layer 5A (the front horizontal alignment film 9a is (Orientation processing direction), and rises uniformly so as to be substantially parallel or substantially perpendicular to the optical compensation layer 1 on the rear side.
In the discotic liquid crystal molecule 11b of the display liquid crystal layer 5A, the molecular axis is aligned with the alignment direction of the liquid crystal molecules 6a on the rear surface side of the display liquid crystal layer 5A (the rear horizontal alignment film 9a). (Orientation direction of the alignment).

This liquid crystal display element is composed of the display liquid crystal layer 5.
The liquid crystal molecules 6a of A are controlled and displayed by applying an electric field between the display control electrodes 7 and 8 in each pixel region, and a display is performed. The effect of the liquid crystal molecules 6a near the liquid crystal molecules 6a in the vicinity of the liquid crystal molecules 6a from the initial alignment state on the display characteristics is determined by the optical compensation layer 10 made of the discotic liquid crystal.
a, 10b.

That is, the liquid crystal display device of this embodiment is
It is of a TN type, and the liquid crystal molecules of the display liquid crystal layer 5A are aligned in accordance with an applied electric field so as to rise with respect to the inner substrates 3 and 4 while maintaining a twist alignment state. Even when an electric field is applied, the surface portion of the display liquid crystal layer 5A, that is, the liquid crystal molecules 6a in the vicinity of the substrate which is strongly subjected to the alignment control force by the horizontal alignment film 9a, have a pretilt angle or Since the liquid crystal layer 5A is still lying down at a close angle, the change in the birefringence Δn of the liquid crystal when an electric field is applied to the display liquid crystal layer 5A is not uniform over the entire liquid crystal layer thickness. The difference in birefringence Δn affects the display characteristics of the liquid crystal display element.

The influence on the display characteristics due to the fact that the liquid crystal molecules 6a in the surface layer of the display liquid crystal layer 5A hardly change from the initial alignment state is caused by the display in the front direction of the screen (in the vicinity of the direction perpendicular to the screen). The contrast of the display when viewed from an oblique direction is greatly reduced as compared with the contrast when viewed from ()).

On the other hand, the optical compensation layers 10a and 10b
The discotic liquid crystal molecules 11 are substantially horizontally oriented in a falling direction on one of the surface facing the display liquid crystal layer 5A and the opposite surface, and substantially discotically aligned on the other surface. Since the liquid crystal molecules 11 are vertically aligned, the alignment state of the liquid crystal molecules 11 and the alignment state of the liquid crystal molecules in the display liquid crystal layer are opposite to each other, and the retardation of the liquid crystal molecules is discotic liquid crystal. Has no direction.

Therefore, according to this liquid crystal display element, the center of the liquid crystal layer thickness of the display liquid crystal layer 5A caused by the fact that the liquid crystal molecules 6a in the surface layer of the display liquid crystal layer 5A hardly change from the initial alignment state. The effect on the display characteristics due to the difference in the birefringence Δn between the portion and the surface layer portion is compensated by the optical compensation layers 10a and 10b made of the discotic liquid crystal, and the viewing angle is widened over a wide range of directions. it can.

Further, in this liquid crystal display element, since the display liquid crystal layer 5A is provided between the pair of horizontal alignment films 9a, both the one surface and the other surface of the display liquid crystal layer 5A are provided. In the surface layer portion, a difference in birefringence Δn occurs because the liquid crystal molecules 6a hardly change from the initial alignment state. In this embodiment, a pair of discotic liquid crystals is sandwiched between the display liquid crystal layer 5A. Optical compensation layer 1
0a and 10b are arranged such that the surfaces of the discotic liquid crystal molecules 11 having the same alignment state face each other, so that the liquid crystal molecules 6a in the surface layer of one surface and the other surface of the display liquid crystal layer 5A are arranged. Can be compensated by the pair of optical compensation layers 10a and 10b due to little change from the initial alignment state, and the viewing angle can be widened over a wide range.

Further, in this embodiment, the optical compensation layers 10a and 10b are formed of a discotic liquid crystal exhibiting a liquid crystal phase at room temperature.
0b, the optical compensation adjustment electrodes 12 and 13 are provided. By controlling the voltage applied between the optical compensation adjustment electrodes 12 and 13, the optical compensation layer 1
0a, 10b, the orientation of the discotic liquid crystal molecules 11 can be changed. Therefore, the retardation of the pair of optical compensation layers 10a, 10b is controlled in accordance with the electric field applied to the display liquid crystal layer 5A. ,
The effect of compensating the effect on the display characteristics due to the fact that the liquid crystal molecules 6a in the surface layer of the display liquid crystal layer 5A hardly change from the initial alignment state can be changed, and the viewing angle characteristics of the liquid crystal display element can be arbitrarily changed. Can be controlled.

Although the liquid crystal display device of the first embodiment is of the TN type, the present invention is also applicable to STN type liquid crystal display devices and ferroelectric or antiferroelectric liquid crystal display devices. Can be applied.

When the present invention is applied to an STN-type liquid crystal display element, the display liquid crystal layer 5A is formed by using 18 liquid crystal molecules 6a.
When applied to a ferroelectric or antiferroelectric liquid crystal display device, the nematic liquid crystal layer having a positive dielectric anisotropy oriented at a twist angle of 0 to 270 degrees (preferably 220 to 250 degrees) is used. The display liquid crystal layer 5A may be a ferroelectric liquid crystal layer or an antiferroelectric liquid crystal layer. In either case, the display liquid crystal layer 5A is provided between the pair of horizontal alignment films 9a. A pair of optical compensation layers 10 made of the discotic liquid crystal, with the liquid crystal layer 5A interposed therebetween.
What is necessary is just to arrange | position a and 10b so that the surface where the orientation state of the said discotic liquid crystal molecule 10 is the same may mutually face.

FIG. 2 is a sectional view of a part of a liquid crystal display device according to a second embodiment of the present invention. In the liquid crystal display device of this embodiment, the display liquid crystal layer 5B has a nematic having a negative dielectric anisotropy. It is made of liquid crystal, and the liquid crystal molecules 6b are homeotropically aligned.

That is, in this embodiment, vertical alignment films 9b each having vertical alignment are provided on the inner surfaces of a pair of inner substrates 3 and 4 which face each other with the display liquid crystal layer 5B interposed therebetween, and the liquid crystal molecules 6b are It is tropically aligned. Note that the vertical alignment film 9b has been subjected to an alignment process for regulating the falling direction of the liquid crystal molecules 6b.

This liquid crystal display element is composed of the display liquid crystal layer 5.
The orientation state of the liquid crystal molecules 6b of B is changed from the initial homeotropic orientation state to the inner substrates 3 and 4 by applying an electric field between the display control electrodes 7 and 8 in each pixel region. Change and display.

In this liquid crystal display element, the liquid crystal molecules 6b of the display liquid crystal layer 5B are oriented so as to fall down from the initial homeotropic orientation state to the inner substrates 3 and 4 according to the applied electric field. However, the display liquid crystal layer 5B
The liquid crystal molecules 6b near the substrate, which is strongly subjected to the alignment control force by the vertical alignment film 9b, are aligned with the inner substrates 3 and 4 at an angle perpendicular to or close to that angle even when an electric field is applied. Therefore, the change in the birefringence Δn of the liquid crystal when an electric field is applied to the display liquid crystal layer 5B is not uniform over the entire liquid crystal layer thickness, and differs between the central portion and the surface layer portion of the liquid crystal layer thickness. The difference of the birefringence Δn is
It affects the display characteristics of the liquid crystal display device.

Since the display liquid crystal layer 5B is provided between the pair of vertical alignment films 9b, the liquid crystal layer 5B is provided on both the surface layers of one surface and the other surface of the display liquid crystal layer 5B. There is a difference in birefringence Δn due to the fact that the molecule 6a hardly changes from the initial alignment state.

Therefore, in this embodiment, the pair of optical compensation layers 10a and 10b made of the discotic liquid crystal is sandwiched between the display liquid crystal layer 5B so that the discotic liquid crystal molecules 11 have the same alignment state. Certain surfaces are placed facing each other.

That is, in this embodiment, of the substrates 1, 3 and 2, 4 opposed to each other with the optical compensation layers 10a, 10b interposed therebetween, the substrate on the display liquid crystal layer 5B side (inner substrate).
A vertical alignment film 14 is provided on 3 and 4 and substrates 1 and 2 on the opposite side are provided.
2 is provided with a vertical alignment film 14, and therefore the discotic liquid crystal molecules 1 of the optical compensation layers 10a and 10b are provided.
As shown in FIG. 2, each of the liquid crystal elements 1 rises substantially vertically on the surface facing the display liquid crystal layer 5B, and falls down substantially horizontally on the opposite surface, and faces the display liquid crystal layer 5B. It is oriented so as to gradually fall from the vertical state toward the opposite surface from the surface.

The vertical alignment film 14 has been subjected to an alignment treatment for regulating the rising alignment state of the discotic liquid crystal molecules 10, and the discotic liquid crystal molecules of the pair of front optical compensation layers 10a and 10b are formed. Numerals 11 are such that, on the surface facing the display liquid crystal layer 5B, the molecular axis perpendicular to the disk-shaped molecular surface is substantially parallel or substantially perpendicular to the falling direction of the liquid crystal molecules 6b of the display liquid crystal layer 5B. It is uniformly rising and oriented.

In the liquid crystal display device of this embodiment, the display liquid crystal layer 5B is a nematic liquid crystal layer in which liquid crystal molecules 6b are homeotropically aligned and has a negative dielectric anisotropy. Although the alignment state of the discotic liquid crystal molecules 11 of 10a and 10b is opposite to that of the first embodiment shown in FIG. 1, the other configuration is the same as that of the first embodiment. Are given the same reference numerals and are omitted.

According to the liquid crystal display device of this embodiment, the liquid crystal molecules 6b in the surface layer of the display liquid crystal layer 5B, that is, in the vicinity of the substrate which is strongly subjected to the alignment control force by the vertical alignment film 9b,
Even when an electric field is applied, the liquid crystal layer 5B does not horizontally align with the surfaces of the inner substrates 3 and 4 opposed to each other with the display liquid crystal layer 5B interposed therebetween. The discotic effect on the display characteristics due to the difference in the orientation state of the liquid crystal molecules 6b in the surface layer portion of the liquid crystal layer 5B and the difference in the birefringence Δn between the central portion of the liquid crystal layer thickness of the display liquid crystal layer 5B and the surface layer portion. Compensation is performed by the optical compensation layers 10a and 10b made of liquid crystal, and the viewing angle can be widened over a wide range.

Further, in this embodiment, a pair of optical compensation layers 10a and 10b made of discotic liquid crystal are sandwiched between the display liquid crystal layer 5B and the surface where the discotic liquid crystal molecules 11 have the same alignment state. Are arranged so as to face each other, so that the difference in birefringence Δn between the surface layer portion on both the one surface and the other surface of the display liquid crystal layer 5B and the central portion of the liquid crystal layer thickness is determined. 10a and 10b compensate, and the viewing angle can be widened over a wide range.

Also in this embodiment, the optical compensation layers 10a and 10b are discotic liquid crystal layers exhibiting a liquid crystal phase at room temperature, and the alignment state of the discotic liquid crystal molecules 11 is controlled by the optical compensation adjusting electrode. 12,
13, the retardation of the optical compensation layers 10a and 10b is controlled in accordance with the electric field applied to the display liquid crystal layer 5B. , 10b can be changed to change the viewing angle characteristics of the display.

In the first and second embodiments,
Display liquid crystal layers 5A, 5 of the optical compensation layers 10a, 10b
The alignment state of the discotic liquid crystal molecules 11 on the B-side surface is determined by the optical compensation layer 10 of the display liquid crystal layers 5A and 5B.
The alignment state of the liquid crystal molecules 5a and 5b on the surface adjacent to the optical compensation layers 10a and 10b (the horizontal alignment in the first embodiment and the vertical alignment in the second embodiment) is the same.
The alignment states of the discotic liquid crystal molecules 11 of a and 10b may be reversed from those in the above embodiment.

Further, in the first and second embodiments, the pair of optical compensation layers 10a and 10b are disposed so as to sandwich the display liquid crystal layers 5A and 5B.
0a and 10b may be provided in only one of them, and even in that case, the display characteristics due to the fact that the liquid crystal molecules 6a and 6b in the surface layer portions of the display liquid crystal layers 5A and 5B hardly change from the initial alignment state. Is compensated by the one optical compensation layer 10a or 10b, and the viewing angle can be widened over a wide range.

In the liquid crystal display elements of the first and second embodiments, the display liquid crystal layers 5A and 6b are formed of a pair of alignment films having the same alignment (the horizontal alignment film 9 in the first embodiment).
a, Second Embodiment Although provided between the vertical alignment films 9b), the present invention can also be applied to a hybrid alignment type liquid crystal display device.

FIG. 3 is a sectional view of a part of a liquid crystal display device according to a third embodiment of the present invention. In this liquid crystal display device, the display liquid crystal layer 5C is made of a nematic liquid crystal having a positive dielectric anisotropy. The liquid crystal molecules 6c are in a hybrid alignment.

In this embodiment, the display liquid crystal layer 5C
The liquid crystal molecules 6c of the display liquid crystal layer 5C are provided from the rear side to the front side by providing a vertical alignment film 9b on the front side and a horizontal alignment film 9a having been subjected to alignment processing in a predetermined direction on the rear side. The hybrid orientation is performed so as to change from the horizontal orientation state to the vertical orientation state toward.

This liquid crystal display element is composed of the display liquid crystal layer 5.
The alignment state of the liquid crystal molecules 6c of C is raised from the initial hybrid alignment state to the inner substrates 3 and 4 by applying an electric field between the display control electrodes 7 and 8 in each pixel region. Change and display.

In this liquid crystal display element, the liquid crystal molecules 6c of the display liquid crystal layer 5C are aligned according to the applied electric field so as to rise from the initial hybrid alignment state to the inner substrates 3 and 4 surfaces. Of the surface layer portions on one surface and the other surface of the display liquid crystal layer 5C, the rear surface portion whose initial alignment state is horizontal alignment, that is, the rear substrate 4 which is strongly subjected to the alignment regulating force by the horizontal alignment film 9a. Liquid crystal molecules 6 near
c indicates that the birefringence of the liquid crystal when an electric field is applied to the display liquid crystal layer 5C is maintained even if an electric field is applied, since the liquid crystal layer 5C remains in a state of falling at or near a pretilt angle with respect to the substrate 4 surface. The change in Δn is not uniform over the entire thickness of the liquid crystal layer, but is different between the region extending from the center of the liquid crystal layer thickness to the front surface of the liquid crystal layer and the rear surface layer. Affect.

Therefore, in this liquid crystal display element, the difference in birefringence Δn due to the fact that the liquid crystal molecules 6c of the display liquid crystal layer 5C hardly changes from the initial alignment state, that is, the rear side of the display liquid crystal layer 5C. The optical compensation layer 10 made of a discotic liquid crystal is disposed on the optical compensation layer.

The optical compensation layer (discotic liquid crystal layer) 10 is provided between the rear substrate 2 of the pair of front and rear transparent substrates 1 and 2 and the inner substrate 4 disposed on the inner side of the rear substrate 2. Is provided.

A pair of substrates 2 and 4 opposed to each other with the optical compensation layer 10 interposed therebetween is provided on each of the opposing surfaces to form a single transparent film for controlling the alignment state of the discotic liquid crystal. Optical compensation adjusting electrodes 12 and 13 are provided, and alignment films 14 and 15 for regulating the initial alignment state of the discotic liquid crystal are formed on these electrodes 12 and 13 respectively.

Of the alignment films 14 and 15, the alignment film 15 on the side facing the display liquid crystal layer 5 C is a horizontal alignment film,
The alignment film 14 on the opposite side is a vertical alignment film, and the discotic liquid crystal molecules 11 of the optical compensation layer 10 correspond to FIG.
As described above, the liquid crystal layer 5C is oriented horizontally horizontally on the surface facing the display liquid crystal layer 5C, and substantially vertically rises on the surface opposite to the display liquid crystal layer 5C, and the surface opposite to the surface facing the display liquid crystal layer 5C. , It is oriented so as to gradually rise vertically from the lying state.

The horizontal alignment film 15 has been subjected to an alignment treatment for regulating the rising alignment state of the discotic liquid crystal molecules 11, and the discotic liquid crystal molecules 11 of the optical compensation layer 10 are provided with a display liquid crystal. On the surface opposite to the layer 5C, the molecular axis is aligned with the display liquid crystal layer 5C.
Orientation of the liquid crystal molecules 6c on the rear surface side (the inner substrate 4
(The orientation processing direction of the horizontal alignment film 9a provided on the front surface of the substrate).

In the liquid crystal display element of this embodiment, the display liquid crystal layer 5C is a nematic liquid crystal layer in which liquid crystal molecules 6c are hybrid-aligned and has a positive dielectric anisotropy. Although the layer 10 is provided only on the rear surface side of the display liquid crystal layer 5C, the other configuration is the same as that of the first embodiment, and the same description will be omitted with the same reference numerals in the drawings.

However, in this embodiment, the display liquid crystal layer 5
Since it is not necessary to provide the optical compensation layer 10 on the front side of C, the front electrode 7 of the display control electrodes for applying an electric field to the display liquid crystal layer 5C and the display liquid crystal layer 5C The vertical alignment film 9b of the alignment films for hybrid alignment of the liquid crystal molecules 6c is provided on the inner surface of the front substrate 1 of the pair of front and rear transparent substrates 1 and 2.

According to the liquid crystal display device of this embodiment, the display liquid crystal layer 5C has a dielectric alignment in which the liquid crystal molecules 6c are hybrid-aligned so that the liquid crystal molecules 6c change from the horizontal alignment state to the vertical alignment state from the rear side to the front side. An isotropic nematic liquid crystal layer, and a surface layer portion on the rear surface side of the display liquid crystal layer 5C;
That is, the liquid crystal molecules 6b in the vicinity of the substrate, which are strongly subjected to the alignment control force by the horizontal alignment film 9a, remain at the pretilt angle or an angle close to the pretilt angle with respect to the substrates 3 and 4 even if an electric field is applied. The birefringence Δn between the center of the liquid crystal layer thickness of the display liquid crystal layer 5C and the surface layer portion, which is caused by the fact that the liquid crystal molecules 6b in the surface layer of the display liquid crystal layer 5C hardly change from the initial alignment state. The influence on the display characteristics due to the difference is compensated by the optical compensation layer 10 made of the discotic liquid crystal, and the viewing angle can be widened over a wide range.

Also in this embodiment, the optical compensation layer 10 is a discotic liquid crystal layer exhibiting a liquid crystal phase at room temperature, and the orientation state of the discotic liquid crystal molecules 11 is changed by the optical compensation adjusting electrode 12 13, the retardation of the optical compensation layer 10 is controlled in accordance with the electric field applied to the display liquid crystal layer 5C, and the optical compensation layers 10a and 10b are controlled. Change the compensation effect by
The viewing angle characteristics of the display can be changed.

In this embodiment, the optical compensation layer 1
0, the alignment state of the discotic liquid crystal molecules 11 on the surface on the side of the display liquid crystal layer 5C, and the alignment state of the liquid crystal molecules 5c on the surface adjacent to the optical compensation layer 10 of the display liquid crystal layer 5C (horizontal alignment in the embodiment). However, the alignment state of the discotic liquid crystal molecules 11 in the optical compensation layer 10 may be reversed from that in the above embodiment.

Further, in the case of the hybrid alignment type liquid crystal display element, the optical compensation layer 10 is formed by the fact that the liquid crystal molecules 6c of the display liquid crystal layer 5C hardly change from the initial alignment state as in the above embodiment. Although it is desirable to dispose it on the side where the difference in refractive index Δn occurs, the display liquid crystal layer 5
Even if the optical compensation layer 10 is arranged on the side opposite to C, the influence on the display characteristics due to the fact that the liquid crystal molecules 6c in the surface layer of the display liquid crystal layer 5C hardly change from the initial alignment state is compensated. Can be.

In the liquid crystal display device of the third embodiment, the liquid crystal molecules 6c of the display liquid crystal layer 5C are hybrid-aligned from the horizontal state to the vertical state from the rear side to the front side. However, the display liquid crystal layer 5C may be one in which the liquid crystal molecules 6c are hybrid-aligned such that the liquid crystal molecules 6c change from a horizontal alignment state to a vertical alignment state from the front side to the rear side. The liquid crystal of the liquid crystal layer 5C is not limited to a nematic liquid crystal having a positive dielectric anisotropy, and may be a nematic liquid crystal having a negative dielectric anisotropy.

Also in this case, on one side of the display liquid crystal layer 5C, preferably, on the side where the difference in birefringence Δn occurs due to the fact that the liquid crystal molecules 6c hardly change from the initial alignment state (dielectric anisotropy). Is disposed on the horizontal alignment side when a positive nematic liquid crystal is used, and on the horizontal alignment side when a dielectric anisotropy uses a negative nematic liquid crystal) by disposing the optical compensation layer 10 made of the discotic liquid crystal.
It is possible to compensate for the influence on the display characteristics due to the fact that the liquid crystal molecules 6c in the surface layer portion of the display liquid crystal layer 5C hardly change from the initial alignment state.

In the first to third embodiments, the optical compensation layers 10, 10a, and 10b are formed of discotic liquid crystals exhibiting a liquid crystal phase at room temperature. It may be formed by molecular liquid crystal.

FIG. 4 is a sectional view of a part of a liquid crystal display device according to a fourth embodiment of the present invention. In this embodiment, an optical compensation layer is formed of a discotic polymer liquid crystal.

In the liquid crystal display device of this embodiment, the liquid crystal molecules are aligned in a predetermined alignment state between a pair of front and rear transparent substrates (eg, glass substrates) 21 and 22 joined via a frame-shaped sealing material (not shown). Display liquid crystal layer 23, transparent display control electrodes 25 and 26 for applying an electric field to the display liquid crystal layer 23, and a discotic polymer liquid crystal arranged with the display liquid crystal layer 23 interposed therebetween. And a pair of optical compensation layers 27a and 27b made of
In this configuration, a pair of polarizing plates 30 and 31 are arranged on the outer surface of the optical disk 22.

In this embodiment, the display control electrode 2
5 and 26 are formed on a pair of substrates 21 and 22, and on these substrates 21 and 22, the optical compensation layers 27 a and 27 b made of discotic polymer liquid crystal are regulated on the substrate side in a molecular orientation state. An alignment film 28,
The optical compensation layers 27a and 27b and the optical compensation layer 27
a and 27b are sequentially laminated with an alignment film 29 for regulating the alignment state of the liquid crystal molecules 24 of the display liquid crystal layer 23 and the alignment film 29 of the display liquid crystal layer 23. The display liquid crystal layer 23 is provided between the alignment film 29 and the alignment film 29 of the other substrate 22.

The liquid crystal display element of this embodiment is of the active matrix type, and the display control electrode 26 provided on the inner surface of one of the pair of substrates 21 and 22 is connected to a row. The plurality of pixel electrodes arranged in the direction and the column direction, and the display control electrode 25 provided on the inner surface of the other substrate 21 is a single-film counter electrode facing the plurality of pixel electrodes 26, and is shown in FIG. Although omitted,
A plurality of TFTs (thin film transistors) connected to the plurality of pixel electrodes 26, respectively, on the one substrate 22
And a plurality of gate lines for supplying gate signals to the TFTs in each row, and a plurality of data lines for supplying data signals to the TFTs in each column.

The liquid crystal display element of this embodiment is of a TN type, and the liquid crystal layer for display 23 comprises liquid crystal molecules 24.
Is made of a nematic liquid crystal having a twisted orientation and a positive dielectric anisotropy, and the pair of polarizing plates 30 and 31 are arranged with their optical axes (transmission axes or absorption axes) aligned in a predetermined direction. .

That is, the optical compensation layers 27a and 27b
The alignment film 29 for regulating the molecular alignment state on the display liquid crystal layer side and the alignment state of the liquid crystal molecules 24 of the display liquid crystal layer 23 is a horizontal alignment film having a horizontal alignment property. Is made of a polyimide film or the like.

The surface of the horizontal alignment film 29 on the side of the display liquid crystal layer 23 is subjected to an alignment treatment for aligning the liquid crystal molecules 24 of the display liquid crystal layer 23 in a predetermined direction. The alignment direction of the liquid crystal molecules 24 of the display liquid crystal layer 23 in the vicinity of the respective substrates 21 and 22 is regulated by the horizontal alignment film 29.
Twist orientation is performed at a twist angle of about 90 between the two.

Although FIG. 4 schematically shows the alignment state of the liquid crystal molecules 24 in the display liquid crystal layer 23, the liquid crystal molecules 24 lie with a slight pretilt angle with respect to the substrates 21 and 22. In a twisted state, it is twisted.

The alignment film 28 for regulating the molecular alignment on the substrate side of the optical compensation layers 27a and 27b is a vertical alignment film having a vertical alignment property. Although the orientation state of each of the molecules of the discotic polymer liquid crystal to be formed is not shown,
On the surface facing the display liquid crystal layer 23, the liquid crystal layer 23 is oriented horizontally in a horizontal direction, and on the opposite surface, the liquid crystal layer 23 rises substantially vertically, and from the surface facing the display liquid crystal layer 23 toward the opposite surface, It is oriented so that it gradually rises vertically from the lying state.

The vertical alignment film 28 for controlling the molecular alignment on the substrate side of the optical compensation layers 27a and 27b is provided with an alignment treatment for controlling the rising alignment of the discotic polymer liquid crystal molecules. Is applied, and the molecules of the discotic polymer liquid crystal in the front optical compensation layer 27a are on the side opposite to the display liquid crystal layer 23 (front substrate 21 side).
Of the liquid crystal molecules 24 on the front side of the display liquid crystal layer 23,
(The orientation direction of the horizontal alignment film 29 on the front side) rises uniformly so as to be substantially parallel or substantially perpendicular to the alignment direction. The molecules of the discotic polymer liquid crystal in the optical compensation layer 27b on the rear side are used for display. On the surface opposite to the liquid crystal layer 23 (on the rear substrate 22 side), the molecular axis is aligned with the alignment direction of the liquid crystal molecules 24 on the rear surface side of the display liquid crystal layer 23 (the alignment processing direction of the rear horizontal alignment film 29). It is uniformly raised and oriented so as to be substantially parallel or substantially orthogonal.

After the vertical alignment film 28 is formed on the substrates 21 and 22, the optical compensation layers 27a and 27b are coated with, for example, a photocurable discotic polymer liquid crystal to a predetermined thickness. Along with coating uniformly, a horizontal alignment film 29 made of the polyimide film or the like is further stacked thereon, and in this state, the discotic polymer liquid crystal is once heated to an isotropic phase transition temperature, and then gradually cooled. By gradually returning to the liquid crystal phase, the molecules of the discotic polymer liquid crystal are aligned in an alignment state regulated by the alignment films 28 and 29, and thereafter, the discotic polymer liquid crystal is cured by light irradiation. The alignment state of the discotic polymer liquid crystal in the optical compensation layers 27a and 27b is always constant. A.

The optical compensation layers 27a and 27b are
The optical compensation layers 27a and 27b may be formed in the same manner as described above by simply changing the means for curing the discotic polymer liquid crystal to heating. can do.

This liquid crystal display element is composed of the liquid crystal layer 2 for display.
3 is controlled by applying an electric field between the display control electrodes 25 and 26 of each pixel region to display the liquid crystal molecules 24, and the surface layer of the display liquid crystal layer 23, that is, the pair of substrates 21 and The effect on the display characteristics due to the fact that the liquid crystal molecules 24 near 22 do not substantially change from the initial alignment state is compensated without directivity by the optical compensation layers 27a and 27b made of the discotic polymer liquid crystal. is there.

In the liquid crystal display device of this embodiment, the optical compensation layers 27a and 27b are formed of discotic polymer liquid crystal.
The effect of compensating for the effect on the display characteristics due to the fact that the liquid crystal molecules 24 in the surface layer of the layer hardly change from the initial alignment state is as follows.
Since it is basically the same as the liquid crystal display device of the first embodiment having the optical compensation layer made of a discotic liquid crystal exhibiting a liquid crystal phase at room temperature, the description thereof is omitted.

According to the liquid crystal display device of this embodiment, the influence on the display characteristics due to the fact that the liquid crystal molecules 24 in the surface layer of the display liquid crystal layer 23 hardly change from the initial alignment state is compensated for, and a wide range of view is obtained. The corners can be widened.

Further, in this embodiment, since the optical compensation layers 27a and 27b are formed of discotic polymer liquid crystal, the optical compensation layers 27a and 27b can be handled as a solid, and therefore, the liquid crystal display element Can be simplified and the thickness can be reduced.

That is, for example, when the optical compensation layers 10a and 10b are formed of a discotic liquid crystal exhibiting a liquid crystal phase at room temperature as in the first embodiment described above, as shown in FIG. 5A and optical compensation layer 10
a and 10b are provided between the inner substrates 3 and 4 to control the display control electrodes 7 and 8 and the alignment state of the liquid crystal molecules 6a of the display liquid crystal layer 5A. Although it is necessary to form an alignment film 9a and an alignment film 13 for regulating the alignment state of the discotic liquid crystal molecules 11 of the optical compensation layers 10a and 10b, in this embodiment, the optical compensation layers 27a and 27b are formed. Can be treated as a solid, so the inner substrate is not necessary, and therefore
Compared with the first embodiment, the structure of the liquid crystal display device can be simplified and the thickness thereof can be reduced.

In the fourth embodiment, the display control electrodes 25 and 2 for applying an electric field to the display liquid crystal layer 23 are used.
6 are formed on a pair of substrates 21 and 22, and optical compensation layers 27a and 27b are provided between the display control electrodes 25 and 26 and the display liquid crystal layer 23, respectively. Electrodes 25 and 26 and optical compensation layers 27a and 2
7b may be reversed.

FIG. 5 is a cross-sectional view of a part of a liquid crystal display device according to a fifth embodiment of the present invention. In this embodiment, the optical compensation layers 27a and 27 made of a discotic polymer liquid crystal are used.
7b is formed on a pair of substrates 21 and 22. A display control electrode for applying an electric field to the display liquid crystal layer 23 is provided between the optical compensation layers 27a and 27b and the display liquid crystal layer 23, respectively. 25 and 26 are provided, and the other configuration is basically the same as that of the fourth embodiment.

The optical compensation layers 27a and 27b are
After the vertical alignment film 28 is formed on each of the pair of substrates 21 and 22, a photo-curable or thermo-curable discotic polymer liquid crystal is uniformly applied to a predetermined thickness on the vertical alignment film 28. Then, a horizontal alignment film 29a made of a polyimide film or the like is overlaid, and in this state, the molecules of the discotic polymer liquid crystal are once heated to an isotropic phase transition temperature and gradually cooled to form the alignment films 28, 2
The display control electrodes 25 and 26 are formed on the horizontal alignment film 29a by aligning them in an alignment state regulated by 9a and thereafter curing the discotic polymer liquid crystal. A horizontal alignment film 29b for regulating the alignment state of the liquid crystal molecules 24 of the display liquid crystal layer 23 is provided thereon.

According to this embodiment, optical compensation layers 27a and 27b made of discotic polymer liquid crystal are formed on a pair of substrates 21 and 22, and these optical compensation layers 27a and 27b are formed.
Since the display control electrodes 25 and 26 are provided between the display liquid crystal layer 23 and the display liquid crystal layer 23, respectively.
In addition, an electric field without a voltage drop due to the optical compensation layers 27a and 27b can be applied.

In the fourth and fifth embodiments,
A pair of optical compensation layers 27a,
27b, the optical compensation layers 27a, 27
b may be provided with only one of them. Even in this case, the influence on the display characteristics due to the fact that the liquid crystal molecules 24 on the surface layer of the display liquid crystal layer 23 hardly change from the initial alignment state is reduced. Optical compensation layer 27a or 27b
And the viewing angle can be widened over a wide range.

The fourth and fifth embodiments are basically similar to the optical compensation layer 10 of the first embodiment shown in FIG.
a and 10b are replaced by optical compensation layers 27a and 27b made of discotic polymer liquid crystal, and are not limited to TN-type liquid crystal display elements, but may be STN (super twisted nematic) type, ferroelectric or anti-static type. It can also be applied to ferroelectric liquid crystal display devices and the like.

Further, also in the liquid crystal display devices of the second and third embodiments shown in FIGS. 2 and 3, the optical compensation layers 10a, 10b and 10 are replaced with optical compensation layers made of discotic polymer liquid crystal. This makes it possible to simplify the structure of the liquid crystal display element and reduce its thickness.

Although the liquid crystal display elements of the first to fifth embodiments are of an active matrix type, the present invention is directed to a plurality of display control electrodes (scanning lines) on the inner surface of one substrate along the row direction. Electrodes) and a plurality of display control electrodes (signal electrodes) along the column direction on the inner surface of the other substrate.

Further, the present invention provides a plurality of color regions corresponding to the plurality of pixel regions (a plurality of pixel electrodes and a plurality of opposing electrodes in an active matrix type liquid crystal display device). The present invention can also be applied to a liquid crystal display device having a filter, for example, a three-color filter of red, green, and blue and displaying a multicolor image such as a full-color image.

When the liquid crystal display elements of the first to third embodiments shown in FIGS. 1 to 3 are provided with a plurality of color filters, the color filters are
a, 5b, and 5c, preferably between the inner substrate 3 or 4 and the display control electrode 7 or 8, and the fourth and fourth surfaces shown in FIGS. When the liquid crystal display element of the fifth embodiment is provided with a plurality of color filters, the color filters are preferably provided between the substrate 21 or 22 and the display control electrodes 25 or 26.

The liquid crystal display element is provided with a reflector on the back surface thereof and is of a reflection type for displaying by using external light, and a backlight is used for displaying by using illumination light from the backlight. There is a transmissive type, and among the reflective type liquid crystal display elements, there is a type in which one polarizing plate is provided only on the front surface thereof. However, the present invention is applicable to any of the liquid crystal display elements. The present invention can also be applied to a so-called two-way display type liquid crystal display device capable of both a reflection type and a transmission type display.

[0108]

According to the present invention, there is provided a liquid crystal display device having a display liquid crystal layer in which liquid crystal molecules are aligned in a predetermined alignment state, a display control electrode for applying an electric field to the display liquid crystal layer, and a display device. An optical compensation layer provided on at least one surface side of the liquid crystal layer, wherein the optical compensation layer is made of a discotic liquid crystal, and the discotic liquid crystal molecules are
The liquid crystal display device is characterized in that one of the surface facing the display liquid crystal layer and the opposite surface is oriented horizontally in a horizontal orientation, and the other surface is oriented substantially vertically in a rising orientation. According to the liquid crystal display device, it is possible to compensate for the influence on the display characteristics due to the fact that the liquid crystal molecules in the surface layer portion of the display liquid crystal layer hardly change from the initial alignment state, and to widen the viewing angle over a wide range.

In the liquid crystal display device according to the present invention, when the display liquid crystal layer is provided between a pair of alignment films having the same alignment, either horizontal alignment or vertical alignment, A pair of optical compensation layers composed of the discotic liquid crystal may be disposed with the surfaces having the same orientation state of the discotic liquid crystal molecules facing each other, with the liquid crystal layer interposed therebetween. The pair of optical compensation layers compensates for the effect on display characteristics caused by the fact that the liquid crystal molecules on the surface layer on one surface and the other surface of the display liquid crystal layer hardly change from the initial alignment state, and provides a wide field of view. The corners can be widened.

The discotic liquid crystal used in the optical compensation layer may be a discotic liquid crystal exhibiting a liquid crystal phase at room temperature or a discotic polymer liquid crystal. If an optical compensation adjusting electrode for controlling the alignment state of the discotic liquid crystal is provided across the optical compensation layer, the voltage applied between the optical compensation adjusting electrodes is controlled to control the discotic liquid crystal. The alignment state of the tick liquid crystal molecules can be changed, and therefore, the compensation effect of the optical compensation layer is changed according to the electric field applied to the display liquid crystal layer, and the viewing angle characteristics of display are arbitrarily adjusted. Can be.

If the optical compensation layer is a discotic polymer liquid crystal layer, a display control electrode for applying an electric field to the display liquid crystal layer and the display liquid crystal layer are provided in a laminated manner. While simplifying the structure of the display element,
Its thickness can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a part of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a part of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a part of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a part of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a part of a liquid crystal display device according to a fifth embodiment of the present invention.

[Explanation of symbols]

1, 2, substrate 3, 4, inner substrate 5A, 5B, 5C, display liquid crystal layer 6a, 6b, 6c, liquid crystal molecule 7, 8, display control electrode 9a, horizontal alignment film 9b, vertical alignment film 10, 10a Reference numeral 10b: Optical compensation layer (a discotic liquid crystal layer showing a liquid crystal phase at normal temperature) 11: Discotic liquid crystal molecules 12, 13, Optical compensation adjustment electrode 14: Vertical alignment film 15: Horizontal alignment film 16, 17, Polarizing plate 21 , 22 ... substrate 23 ... display liquid crystal layer 24 ... liquid crystal molecules 25, 26 ... display control electrodes 27a, 27b ... optical compensation layer (discotic polymer liquid crystal layer) 28 ... vertical alignment film 29, 29a, 29b ... horizontal alignment Film 30, 31 ... Polarizing plate

Claims (4)

[Claims] 1. A display liquid crystal layer in which liquid crystal molecules are aligned in a predetermined alignment state, a display control electrode for applying an electric field to the display liquid crystal layer, and at least one surface side of the display liquid crystal layer. An optical compensation layer is provided, the optical compensation layer is made of a discotic liquid crystal, and the discotic liquid crystal molecules have one of a surface facing the display liquid crystal layer and an opposite surface thereof. A liquid crystal display element characterized in that the liquid crystal display element is oriented horizontally in a horizontal direction on the surface and is vertically oriented in the other surface. 2. The display liquid crystal layer is provided between a pair of alignment films having the same orientation of either horizontal orientation or vertical orientation, and sandwiches the display liquid crystal layer.
2. The liquid crystal display device according to claim 1, wherein the pair of optical compensation layers made of the discotic liquid crystal are arranged so that surfaces having the same alignment state of the discotic liquid crystal molecules face each other. 3. The optical compensation layer is made of a discotic liquid crystal exhibiting a liquid crystal phase at room temperature. The optical compensation layer is sandwiched between the optical compensation layer and the optical compensation layer for controlling the alignment state of the discotic liquid crystal. 3. The liquid crystal display device according to claim 1, further comprising an electrode. 4. The liquid crystal display device according to claim 1, wherein said optical compensation layer is made of a discotic polymer liquid crystal.