JP2003098560A - Optical element, optical deflection element and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an element in which a homogeneous alignment state which is bistable in two directions of a ferroelectric liquid crystal in an inclined area is realized, as an optical element constituted of a liquid crystal cell whose substrates are not parallel to each other using a chiral smectic C layer, and to enable a high speed shift of an optical path with a simple constitution. SOLUTION: A homogeneous alignment state which is bistable in two directions of the ferroelectric liquid crystal is formed in the liquid crystal cell having the inclined area where nearly transparent two substrates 3 and 4 each having a transparent electrode 2 and a liquid crystal alignment layer 6 are not parallel to each other and an inclined angle θ is fixed, and emitted light is deflected by switching a director of liquid crystal molecules L. Alignment treatment is performed so that arrangement directions of liquid crystal molecules on counter substrates are parallel to each other (so that arrangement directions of the liquid crystal molecules between substrates are in the same plane). The direction of alignment treatment is preferably set so that one stable direction of the liquid crystal coincides with the direction vertical to the maximum inclined direction in the inclined area in order to perform stable switching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light deflection element that changes the direction of light according to an electric signal, and an image display device using the light deflection element, and is applicable to electronic display devices such as projection displays and head mounted displays. Optical deflection technology.

[0002]

_2. Description of the Related Art Conventionally, KH ₂ PO ₄ (KDP), NH ₄ H ₂ PO ₄ (AD
P), LiNbO ₃ , LiTaO ₃ , GaAs, CdTe
Electro-optical devices using materials with large primary electro-optical effect (Pockels effect), materials with large secondary electro-optical effect such as KTN, SrTiO ₃ , CS ₂ and nitrobenzene, glass, silica, TeO ₂ Acousto-optic devices using materials such as (for example, Shoji Aoki; “Optoelectronic Device”, Shokoido) are known.
Generally, these require a long optical path length in order to obtain a sufficiently large light deflection amount, and their materials are expensive, so that their applications are limited.

On the other hand, various optical elements, which are light deflection elements using a liquid crystal material, have been proposed.
There are proposal examples as shown below. For example, Japanese Patent Laid-Open No. 6-1
According to Japanese Patent No. 8940, a light beam shifter including an artificial birefringent plate is proposed for the purpose of reducing the light loss of the optical space switch. Specifically, two wedge-shaped transparent substrates are arranged opposite to each other, and a light beam shifter having a liquid crystal layer sandwiched between the transparent substrates and a light beam shifter connected to the rear surface of the matrix type deflection control element are provided. A beam shifter has been proposed. In addition, a light beam shifter in which two wedge-shaped transparent substrates are arranged in opposite directions, matrix driving is possible between the transparent substrates, and a liquid crystal layer that shifts an incident light beam by a half cell is sandwiched is provided. A light beam shifter in which half cells are shifted and connected in multiple stages has been proposed.

However, in the example of Japanese Patent Laid-Open No. 6-18940, since nematic liquid crystal is used as the liquid crystal material, it is difficult to increase the response speed to sub-milliseconds, and for applications requiring high-speed switching. It cannot be used.

Further, according to Japanese Patent Laid-Open No. 9-133904, there is provided an optical deflection switch capable of obtaining a large deflection, high in deflection efficiency, and capable of arbitrarily setting a deflection angle and a deflection distance. Proposed. Specifically, two transparent substrates are arranged to face each other at a predetermined interval, and the surfaces facing each other are subjected to vertical alignment treatment, and a smectic A-phase ferroelectric liquid crystal is sealed between the transparent substrates, It is a liquid crystal element having a driving device that is vertically aligned with respect to the electrode pair, has an electrode pair arranged in parallel with the smectic layer so that an AC electric field can be applied, and applies an AC electric field to the electrode pair. That is, the electroclinic effect of the smectic A-phase ferroelectric liquid crystal is used to change the refraction angle and the displacement direction of the polarized light incident on the liquid crystal layer by the birefringence due to the inclination of the liquid crystal molecules.

However, although the smectic A phase ferroelectric liquid crystal is used in the above-mentioned Japanese Patent Laid-Open No. 9-133904, the smectic A phase has no spontaneous polarization.
High speed operation cannot be expected.

As described above, for the purpose of improving the high speed which was not sufficient in the prior art, the present applicant has previously made a pair of transparent substrates and a homogeneous orientation filled between these substrates. Liquid crystal composed of chiral smectic C phase,
An optical deflecting element comprising an electric field applying unit formed of an electrode pair formed between a pair of the substrate and the liquid crystal, wherein the incident direction of light is set in a direction different from the substrate surface normal direction, and
A pair of transparent substrates, a liquid crystal having a chiral smectic C phase filled between the substrates, and at least one set of electric field applying means are provided, and both substrate surfaces sandwiching the liquid crystal correspond to the light deflection direction. Thus, there is provided an optical deflecting device that is inclined and faces each other, and an optical deflecting device that includes two sets of the above optical deflecting devices that are separated by a predetermined distance in the light traveling direction.

[0008]

In the optical deflecting element and the optical deflecting device submitted by the present applicant, a chiral smectic C liquid crystal is used as a liquid crystal material, and it is possible to switch at an extremely high speed as compared with the prior art. But,
On the other hand, it is difficult for a liquid crystal composed of a chiral smectic C layer to be uniformly aligned in a predetermined region, and there has been no report on a technique for uniformly aligning the liquid crystal particularly when the substrate intervals are non-parallel. .

The present invention has been made in view of the above-mentioned circumstances, and in an optical element including a liquid crystal cell using a chiral smectic C layer and having a non-parallel substrate spacing, a ferroelectric liquid crystal of 2 is formed in an inclined region. An optical element, an optical deflecting element, an optical deflecting device, an optical deflecting device, and the optical deflecting device or the optical deflector, which provide a method for forming a bistable homogeneous alignment state in a direction, and which enables a high-speed optical path shift with a simple configuration. An object of the present invention is to provide an image display device using the device. The purpose corresponding to each claim is described below.

The invention of claim 1 is a chiral smectic C
It is an object of the present invention to provide an optical element having a uniform alignment state in an optical element using a liquid crystal cell in which layers are non-parallel to each other. It is an object of the invention of claim 2 to provide an optical deflection element using the above optical element, which has a uniform deflection characteristic and is capable of high-speed response. It is an object of the invention of claim 3 to provide an optical deflecting element which improves stability of alignment state of liquid crystal molecules during switching and operates with high reliability.

It is an object of the invention of claim 4 to provide a highly efficient light deflection element with improved light utilization efficiency.
It is an object of the invention of claim 5 to provide a highly accurate optical deflection element by removing unnecessary noise light. An object of the invention of claim 6 is to provide a more efficient light deflection element by optimizing the physical properties of the liquid crystal and the characteristics of the incident light.

It is an object of the invention of claim 7 to provide an optical deflecting element which improves the alignment stability of liquid crystal molecules at the time of switching, is efficient, and operates more stably. It is an object of the inventions of claims 8 and 9 to provide an optical element or an optical deflecting element capable of shifting an optical path in a large area. It is an object of the inventions of claims 10 to 12 to provide an optical deflecting device capable of parallel shifting an optical path in one direction.

It is an object of the invention of claim 13 to provide an optical deflecting device capable of parallel shifting the optical path in two directions of XY. It is an object of the invention of claim 14 to provide an image display device having an apparently high definition and a high light utilization efficiency by using an image display element having a small number of pixels.

[0014]

According to a first aspect of the present invention, there are provided two substrates having a transparent electrode film and a liquid crystal alignment film, and a liquid crystal in which liquid crystal molecules are aligned in a predetermined direction on the liquid crystal alignment film. An optical element comprising a liquid crystal cell in which a layer is enclosed between the substrates, wherein the liquid crystal cell has an inclined region in which the two substrates are arranged at a predetermined inclination angle, and the liquid crystal layer is It has a chiral smectic C phase that takes a bistable homogeneous alignment state in two directions in the tilted region, and the alignment directions of the liquid crystal molecules on the liquid crystal alignment films in the tilted regions are in the same plane. It is a feature.

According to a second aspect of the present invention, there is provided an optical deflecting element capable of deflecting the traveling direction of incident linearly polarized light by using the optical element according to the first aspect, wherein each of the bistable homogeneous orientations is provided. It is characterized in that the directions are set so as to be asymmetrical with respect to the polarization direction of the incident linearly polarized light as the central axis.

According to the invention of claim 3, in the invention of claim 2, one stable direction of the bistable homogeneous alignment is aligned with a plane including a direction perpendicular to the maximum tilt direction in the tilt region, It is characterized in that the direction of the alignment treatment is set.

The invention of claim 4 is characterized in that, in the invention of claim 2 or 3, the polarization direction of the incident linearly polarized light is arranged so as to coincide with one stable direction of the bistable homogeneous alignment. It was done.

According to a fifth aspect of the invention, in any one of the second to fourth aspects of the invention, a polarizing plate is provided on the exit side of the liquid crystal cell.

According to a sixth aspect of the present invention, in the invention of the second aspect, the angle between the two directions of the bistable homogeneous orientation is substantially right, and the polarization direction of the incident linearly polarized light is the bistable homogeneous orientation. It is characterized in that it is arranged so as to be parallel to one of the stable directions.

According to the invention of claim 7, in the invention of claim 5, the direction of the alignment treatment is such that one stable direction of the bistable homogeneous alignment coincides with a direction perpendicular to the maximum tilt direction in the tilt region. Is set.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the inclined region is formed by one side of the sawtooth shape by providing a periodic structure having a sawtooth cross section on the inner surface of one of the substrates, It is characterized in that the inclined regions are macroscopically and continuously formed by the saw-toothed periodic structure.

According to a ninth aspect of the present invention, in any one of the second to seventh aspects of the invention, a periodic structure having a sawtooth-shaped cross section is provided on the inner surface of one of the substrates, so that one side of the sawtooth-shaped structure is used. An inclined region is formed, and the inclined region is macroscopically formed continuously by the sawtooth-shaped periodic structure.

A tenth aspect of the present invention is an optical deflecting device having a pair of the optical deflecting elements according to any one of the first to ninth aspects, wherein the first optical deflecting element is in the traveling direction of incident light. Of light refracted in the inclined region of the second optical deflector is incident on the inclined region of the second optical deflector arranged at a constant interval, is refracted again in the inclined region of the second optical deflector, and is emitted. In doing so, so that the deflected light emitted in accordance with the respective orientation directions of the bistable homogeneous orientation is emitted as parallel light, the substrate surface for deflecting the optical path in the first inclined region and the second It is characterized in that an arrangement angle for incident light on a substrate surface for deflecting an optical path in an inclined region is set.

According to the invention of claim 11, in the invention of claim 10, the substrate surface for deflecting the optical path in the first inclined region and the substrate surface for deflecting the optical path in the second inclined region are parallel to each other. It is characterized by being set so that

The invention of claim 12 is the invention of claim 10 or 1.
In the invention of claim 1, the first light deflecting element and the second light deflecting element are configured such that one substrate forming the light deflecting element is shared by one substrate. It is a thing.

The thirteenth aspect of the present invention provides the tenth to first aspects.
2. The first optical deflection device according to any one of 2, a polarization plane rotation unit that rotates the polarization plane of the emitted light of the first optical deflection device substantially at a right angle, and a polarization plane rotation by the polarization plane rotation unit. The second optical deflecting device according to claim 10, wherein the subsequent outgoing light is incident, the maximum inclination direction of the inclined region of the first optical deflecting device, and the second optical deflecting device. It is characterized in that it is arranged so that the maximum tilt direction of the tilt region of the light deflecting device is substantially orthogonal.

According to a fourteenth aspect of the present invention, at least an image display element in which a plurality of pixels capable of controlling light according to image information are two-dimensionally arranged, a light source for illuminating the image display element, and the image display element are provided. 13. An optical member for observing a displayed image pattern, and deflecting an optical path between the image display element and the optical member for each of a plurality of subfields obtained by temporally dividing the image field. The optical deflecting device according to claim 1 or the optical deflecting means according to the optical deflecting device according to claim 13 is provided.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, an optical deflecting element (optical deflecting device, optical deflecting device) deflects an optical path of light by an electric signal from the outside, that is, parallels outgoing light with incident light. It means an optical element capable of shifting the optical path by shifting the optical path, rotating the optical path at a certain angle, or combining the both.

The pixel shift element includes an image display element in which a plurality of pixels capable of controlling light according to at least image information are two-dimensionally arranged, a light source for illuminating the image display element, and an image displayed on the image display element. An optical member for observing the pattern and an optical deflecting unit for deflecting an optical path between the image display element and the optical member for each of a plurality of subfields obtained by temporally dividing the image field are provided. Means a light deflecting means in an image display device for displaying an image pattern in which the display position is displaced according to the deflection of the optical path for each field to multiply and display the apparent number of pixels of the image display element. To do.

A surface-stabilized ferroelectric liquid crystal device made of a chiral smectic C liquid crystal, which is generally known as a display device, takes a bistable homogeneous alignment state and, depending on the polarity of an electric field applied to the display device, this bistable It is possible to switch between different states. Another feature is that the stable state is maintained even when the electric field is cut off in one stable state, and the high-speed response in the smectic C liquid crystal as compared with the smectic A liquid crystal and nematic liquid crystal.

The inventors of the present invention, as an application to a light deflection element,
The distance between two substantially transparent substrates having a transparent electrode film and a liquid crystal alignment film is non-parallel and the tilt angle (angle formed by the surfaces of the opposing substrates) θ
In a liquid crystal cell having a tilted region in which the constant angle is constant, a bistable homogeneous alignment state in two directions is formed by the ferroelectric liquid crystal in the tilted region, and the emitted light with respect to the incident light is controlled by controlling the director of the liquid crystal molecules. The structure which can be rotated and moved was examined. By switching between the bistable alignment states of liquid crystal molecules to switch the refractive index, it is possible to change the traveling direction of light according to the difference in the refractive index at the substrate interface in the inclined region. By appropriately selecting, the desired deflection amount can be obtained.

Here, it was feared that a uniform bistable homogeneous alignment state without defects could be formed in the tilted region of the substrate where the liquid crystal layer thickness was not uniform. However, the alignment direction of liquid crystal molecules on the two substrates was examined. As a result, in the present invention, the alignment treatment is performed so that the liquid crystal molecule alignment directions on the upper and lower substrates facing each other are parallel to each other (so that the liquid crystal molecule alignment directions between the two substrates in the inclined region are in the same plane). This problem is solved by applying. Moreover, when the principle of the optical path shift was confirmed with the optical deflector having such a structure, it was found that the direction of the linearly polarized light incident on the orientation of the liquid crystal molecules with respect to the tilted region plays an important role in the function of the optical path shift. Was found. The present invention provides a method for forming a bistable homogeneous alignment state of a ferroelectric liquid crystal in two directions within an inclined region, and an optical deflecting element capable of high-speed optical path shift with a simple configuration.

According to the present invention, in at least a part of a liquid crystal cell composed of two substantially transparent substrates having a transparent electrode film and a liquid crystal alignment film, there is an inclined region in which the substrate distance is non-parallel and the inclination angle θ is constant. And has a ferroelectric liquid crystal layer capable of taking a bistable homogeneous alignment state in the inclined region by performing an alignment treatment so that the liquid crystal molecule alignment directions on the two substrates in the inclined region are parallel to each other. A light deflection element is provided. The orientation direction of the bistable homogeneous may be any direction with respect to the substrate region, but for stable switching, one stable direction matches the direction perpendicular to the tilt direction of the tilted region (maximum tilt direction with respect to the counter substrate). It is preferable to set the orientation processing direction so that

The incident light to the light deflection element is linearly polarized light, and when two planes of bistable homogeneous alignment are asymmetric with respect to the central axis when the plane of polarization is the central axis, The difference in refractive index from the substrate interface for each alignment state changes, and the angle of emitted light changes.
That is, the function of light deflection can be obtained. Further, by providing a polarizing plate on the exit side of the light deflection element, it is possible to obtain the effect of removing noise light (light components having different polarization angles and polarization planes) contained in the exit light. Further, in order to improve the utilization efficiency of light and obtain a more efficient light deflection element, it is possible to fill the ferroelectric liquid crystal material in which the angle between the two directions of the bistable homogeneous alignment is substantially right. . In order to shift the optical path in a large area, it is possible to form a periodic structure having a sawtooth-shaped cross section inside one side of the substrate as a macroscopically continuous inclined region.

FIG. 1 is a view for explaining a first embodiment of the present invention (corresponding to claims 1 to 7). FIG. 1A is a schematic side view of an optical element (light deflection element). In Fig. 1
FIG. 1B is a schematic diagram illustrating the alignment state of liquid crystal molecules in the AA ′ cross section of FIG. In FIG. 1, 1 is an optical element, 2 is a transparent electrode, 3 and 4 are substrates, 5
Is a spacer, 6 is an alignment film, 7 is a liquid crystal layer, and L is a liquid crystal molecule. In the optical element 1, first, as shown in FIG. 1A, a pair of transparent substrates 3 and 4 having a transparent electrode 2 has an inclination angle (an angle formed by opposing surfaces of transparent substrates) at least at a part thereof. They are provided so as to face each other with θ. The spacer 5 for controlling the inclination angle θ of the substrates 3 and 4 is set at a position where it does not overlap the optical path. Further, an alignment film 6 is formed on the inner surfaces of the substrates 3 and 4, and the molecular arrangement on the two substrates is subjected to alignment treatment in the direction of FIG.
Ferroelectric liquid crystal is filled between them to form the liquid crystal layer 7.

As a prerequisite for accurately performing the optical path shift, it is necessary to form the ferroelectric liquid crystal layer filled between the substrates 3 and 4 having the inclined regions in a bistable homogeneous alignment state without defects. The direction of the alignment treatment for that purpose was examined. Although the alignment state was controlled by performing the alignment treatment in the direction in which the alignment of the liquid crystal molecules L on each substrate intersects with an opening angle of about the cone angle of the liquid crystal material, a good alignment state was not obtained. The degree of alignment defect was the same regardless of the orientation of the inclined surface.

On the other hand, by performing the alignment treatment so that the alignment directions of the liquid crystal molecules L on each substrate, which are shown in FIG. 1B as an example, were parallel to each other, a good alignment state could be obtained. According to this method, it is possible to easily obtain a good orientation state in whichever direction the inclined surface is treated. However, when the thickness of the liquid crystal layer in the tilted region is large, the regulation force of the alignment treatment is weakened and the alignment of the liquid crystal molecules L is disturbed. Further, although the initial bistable orientation state is good, there is concern that the reliability may be deteriorated in continuous use. Therefore, the thickness of the liquid crystal layer 7 suitable for the light deflecting element varies depending on the ferroelectric liquid crystal material used, but is 6 μm.
It is better to keep it below m. It is preferably 4 μm or less.

As the alignment treatment method for the above-described homogeneous alignment, a conventionally known method can be applied. That is, there are a rubbing method, a temperature gradient method, a photo-alignment method and the like. The orientation of the bistable homogeneous array is generated at equal angles on both sides of the alignment treatment direction as the center line, and the polarity of the electric field applied to the liquid crystal cell is changed to produce the first stable orientation as shown in FIG. 1 (B). The direction and the second stable direction can be switched. By performing the alignment treatment such that the liquid crystal molecule alignment directions are parallel to each other, a bistable homogeneous alignment state can be obtained even in the inclined region. As a result, it is possible to improve the yield at the time of manufacturing the device due to the defective alignment, and it is possible to extend the device life.

In order to shift the optical path by switching the bistable liquid crystal directors in two directions, the two directions of the liquid crystal directors are asymmetrical with respect to the linearly polarized plane of the incident light. So it is necessary to set up a bistable orientation.

FIG. 2 is a diagram for explaining the deflecting operation due to the change in the refractive index on the inclined surface of the substrate.
2A shows the operation when the major axis direction of is relatively close to the polarization direction of the incident light, and FIG. 2B shows the operation when the minor axis direction of the liquid crystal molecules is relatively close to the polarization direction of the incident light. It is shown in. When the refractive index of the liquid crystal molecule L in the major axis direction is ne and the refractive index in the minor axis direction is no, the incident linearly polarized light has a refractive index n.
The light is deflected and shifted in accordance with the effective refractive index difference corresponding to the directions of o and ne and the liquid crystal director (either stable direction). As shown in FIG. 2A, when the long axis direction of the liquid crystal molecules L is relatively close to the polarization direction of the incident light, the light feels a large refractive index in the liquid crystal layer 7, so that the liquid crystal layer 7 and the substrate 4 are separated from each other. Refraction is relatively large at the inclined interface, and the light exits at an angle θe with respect to the incident optical axis X.

On the other hand, as shown in FIG. 2B, when the minor axis direction of the liquid crystal molecule L is relatively close to the polarization direction of the incident light, the light feels the refractive index in the liquid crystal layer 7 to be small, so that the liquid crystal layer Refraction is relatively small at the inclined interface between 7 and the substrate 4, and the light is emitted at an angle θo with respect to the incident optical axis X. The angle difference θe−θo between the above two states is the deflection angle. Since the difference between the refraction angles of the two alignment states is used as the deflection angle, it is not necessary that the refraction index ne or no of the liquid crystal molecule L and the refraction index ng of the substrates 3, 4 or the alignment film 6 match. . It suffices that the refractive index difference between the two alignment states is generated with respect to the polarization direction of the incident linearly polarized light. This is because if a bistable direction is installed at a position symmetrical with respect to the incident linearly polarized light, a difference in refractive index does not occur and the function of optical path shift cannot be obtained (claim 2). As described above, when the bistable homogeneous orientation direction is asymmetric with respect to the direction of the incident linearly polarized light, the refractive index changes, and the function of optical path shift capable of high-speed response is obtained. .

FIG. 3 is a view for explaining an arrangement direction suitable for realizing stable operation of liquid crystal molecules. FIG. 3A is a schematic side view of the configuration of the light deflection element, and FIG. )
FIG. 3B is a schematic diagram illustrating the alignment state of the liquid crystal molecules in the section AA ′ of FIG. In FIG.
Reference numeral 1'denotes an optical deflector according to this embodiment in which the alignment direction of liquid crystal molecules is optimized. The bistable homogeneous array direction may be any direction, but in order to operate the liquid crystal molecules stably, one stable direction of the liquid crystal molecules within the tilted region as in the light deflection element 1 ′ in FIG. It is preferable to perform the alignment treatment in a direction perpendicular to the tilt direction which is a stable position.

Regarding the setting of the orientation processing direction, the orientation processing direction can be easily determined by the cone angle of the liquid crystal material used. As described above, no matter which angle the alignment treatment is applied to the inclined surface of the substrate, the bistable direction due to the electric field application occurs at the same angle on both sides with the alignment treatment direction as the center line. For example, when a liquid crystal material having a cone angle of 50 ° is used, as shown by the solid line in FIG. 3B, the angle θ _R of the alignment treatment direction with respect to the direction perpendicular to the inclined surfaces of the substrates 3 and 4 is set to 25 °. By doing so, the first stable direction and the second stable direction as shown in FIG. 3B can be set.
Further, it is possible to obtain the same function by performing the alignment treatment in the direction of the broken line in FIG. 3 (B) (claim 3). Thus, one stable direction of the bistable homogeneous orientation is
By aligning the direction perpendicular to the tilt direction of the tilted region and making it stable with respect to the tilted surface, the stability of the alignment state of liquid crystal molecules at the time of switching is improved, and the optical deflection element with high operation reliability is provided. Is obtained.

As shown in FIG. 3, in a liquid crystal cell formed so that one stable direction of liquid crystal molecules is perpendicular to the tilt direction of the tilted surface of the substrate, in order to perform more efficient light deflection, It is advisable to arrange the direction of the incident linearly polarized light so as to coincide with one stable direction of the bistable homogeneous alignment. By matching the long axis ne of the liquid crystal molecules with the polarization direction, the efficiency is improved and a highly efficient light deflection element is obtained (claim 4).

However, in any of the configurations, when the long axis direction of the liquid crystal molecule L and the polarization direction of the incident light are not horizontal or vertical, that is, the cone angle of the liquid crystal molecule is not 90 degrees, and two stable alignments are obtained. Under the condition that linearly polarized light is obliquely incident on the direction, a noise light component that is not deflected is generated. The polarization plane of this noise light is rotated. In order to remove this noise light, a polarizing plate is provided on the side of the outgoing light to obtain the effect of cutting the noise light component, and the optical path can be shifted reliably, and a more accurate light deflection element can be obtained. Therefore, the contrast can be improved (Claim 5).

The method of aligning a ferroelectric liquid crystal cell having a function as a light deflection element and the direction of linear polarization of incident light have been described above. A highly-functionalized optical deflector that is often used will be described below (corresponding to claims 6 and 7).

FIG. 4 is a schematic front view of an embodiment in which the alignment state of liquid crystal molecules is optimized in the light deflection element according to the present invention, and schematically shows a liquid crystal cell of the light deflection element.
In FIG. 4, 1 "is a high-performance optical deflecting element according to the present embodiment that can efficiently use the refractive index of liquid crystal molecules, 3 is a substrate, and 5 is a spacer. In the optical polarizing element 1",
First, a pair of transparent substrates having transparent electrodes having a structure similar to that shown in FIG. 1 are provided so as to face each other with an inclination angle θ. The spacer 5 for controlling the inclination angle θ of the substrate is set at a position where it does not overlap the optical path. Ferroelectric liquid crystal having a cone angle of almost right angle between the substrates is filled with the alignment treatment so as to take a bistable direction as shown in FIG.

The direction of the incident linearly polarized light is made to coincide with one stable direction of the bistable homogeneous orientation. In FIG. 4, the polarization direction of the incident linearly polarized light is matched with the second stable state. When an electric field is applied to the liquid crystal cell of the light deflecting element 1 ″ so that the ferroelectric liquid crystal layer faces the second stable direction, the incident light is transmitted at an emission angle according to the extraordinary light refractive index ne. Then, when the liquid crystal molecules are oriented in the first stable direction, the linearly polarized light passing through the liquid crystal molecules tilted along the tilted region is transmitted at an emission angle according to the ordinary refractive index no. In this case, since the birefringence of the liquid crystal molecules is used to the maximum, the light utilization efficiency is improved, resulting in a highly efficient light deflecting element, and the polarization rotation of the light passing through the liquid crystal layer. Since it does not occur, there is an advantage that it is not necessary to provide a polarizing plate on the outgoing light side for removing the extraordinary outgoing light (claim 6), that is, the angle between the two directions of the bistable homogeneous alignment is substantially the same. The polarization direction of the incident linearly polarized light at a right angle is bistable homo By arranging so as to be parallel to one of the stable directions of the near alignment, the polarization direction coincides with the directions of the long-axis refractive index ne and the short-axis refractive index no of the liquid crystal molecule, so that more efficient light deflection is performed. be able to.

The bistable two directions of the ferroelectric liquid crystal can be a highly efficient light deflecting element regardless of the angle of arrangement with respect to the inclined region, but in order to operate more stably, it is the same as in claim 2. For the reason, it is preferable to arrange such that one stable direction of the liquid crystal molecules is a direction perpendicular to the tilt direction (direction of FIG. 4) which is a stable position in the tilt region (claim 7). That is, by setting one stable direction of the bistable homogeneous alignment to be a stable position in the tilt region, which is perpendicular to the tilt direction, the alignment stability of liquid crystal molecules during switching is further improved, and highly reliable light deflection is achieved. The device is obtained.

FIG. 5 is a view for explaining another embodiment of the present invention (corresponding to claims 8 and 9). FIG. 5A is a schematic side view of an optical element (optical deflection element). , Fig. 5 (A)
FIG. 5B is a schematic diagram for explaining the alignment state of the liquid crystal molecules in the section AA ′ of FIG. In FIG.
Reference numeral 11 is a light deflection element in the present embodiment, 13 and 14 are substrates, 15 is a spacer, and 17 is a liquid crystal layer made of ferroelectric liquid crystal. In FIG. 5, the alignment film and the transparent electrode required for the liquid crystal cell are not shown.

As shown in FIG. 5A, the light deflection element 11 has a periodic structure having a sawtooth-shaped cross section formed inside a pair of opposing substrates 13 and 14, and both interfaces contacting the liquid crystal layer 17 are mutually adjacent. Opposed to each other with an inclined region. That is, the inclined region in which the angle formed by the surface of the counter substrate is inclined is formed by one side of the sawtooth-shaped inclined surface. Both boards 13, 14
Is provided with a transparent electrode (not shown), and substrates 13 and 14 are provided.
An alignment film (not shown) is formed on the inner surface.
The liquid crystal molecules L are rubbed in the direction shown in (B) so that one stable direction of the liquid crystal molecules L is controlled to be a direction perpendicular to the tilt direction of the sawtooth slope. The thickness of the liquid crystal layer 17 is controlled by the spacer 5 so as to be thinner than about 6 μm at the maximum. In order to prevent the formation of alignment defects, the liquid crystal layer 1
It is preferable to form the saw-tooth shape so that the thickness difference of 7 becomes 1 μm or less. As a method of forming, a glass substrate may be etched or a transparent plastic material may be processed by injection molding or the like. By forming macroscopically continuous inclined regions in this way, an optical element capable of deflecting light in a large area is obtained.

FIG. 6 is a diagram for explaining an embodiment of the optical deflecting device according to the present invention, and is a diagram for explaining the action when the inclined regions of the optical element are arranged to face each other. . In FIG. 6, 21 is an optical deflecting device, 23 and 24 are substrates, 27 is a liquid crystal layer, 28 is an intermediate substrate, T ₁ is a first inclined region, and T ₂ is a second inclined region. In FIG. 6, the illustration of the transparent electrode alignment film, spacers, etc. is omitted. Although the light deflecting element described above can deflect the angle of the emitted light, as shown in FIG. 6, the light refracted in the _first tilted region T ₁ is moved to a second position where the light is refracted at regular intervals. It enters the inclined area T _2, to emit a substantially parallel light is again refracted at the second slope region T _2, disposed first inclined region T ₁ and a second inclined region T ₂ are opposed By doing so, the optical path can be parallel-shifted in one direction. Further, the parallel shift amount can be easily adjusted by adjusting the distance between the two inclined regions T ₁ and T ₂ . The structure shown in FIG. 6 uses the common intermediate substrate 28 for the two tilted regions T ₁ and T ₂ , but the two light deflection elements may be arranged to face each other with a space.

FIG. 7 is a schematic view for explaining another embodiment of an optical deflecting device having a structure in which a pair of sawtooth-shaped substrates are arranged so as to face each other, in which 31 is an optical deflecting device and 3 is an optical deflecting device.
Reference numerals 3 and 34 denote substrates, 37 denotes a liquid crystal layer, and 38 denotes an intermediate substrate. As shown in FIG. 7, by arranging a pair of substrates 33, 34 having a sawtooth surface shape so that the sawtooth shapes face each other, it is possible to shift the optical paths in parallel over a relatively wide area. In FIG. 7, the transparent electrodes, the alignment film, the spacers and the like are omitted (claims 10 to 12).
Corresponding to).

FIG. 8 is a schematic perspective view for explaining an embodiment of a light deflecting device according to the present invention, in which 41a is a first light deflecting device, 41b is a second light deflecting device, and 43 is a light deflecting device.
Is the polarization plane rotating means, T ₁ is the first tilt region, T ₂ is the second tilt region, T ₃ is the third tilt region, T ₄ is the fourth tilt region, and T _L is the maximum tilt in the tilt region. Direction. In the optical deflecting device as described above, the optical path can be shifted only in one direction, but as shown in FIG. 8, the first optical deflecting device 41a that shifts the incident light in parallel in the Y direction, and the first optical deflecting device 41a. A polarization plane rotation means 42 for rotating the polarization plane of the outgoing light of the first light deflection device 41a at a substantially right angle;
It has a second light deflection device 41b which makes the outgoing light after the polarization plane rotation the incident light, and the maximum tilt direction T _L of the tilt region of the first light deflection device 41a and the second light deflection device 41b.
By arranging so that the maximum inclination direction T _L of the inclined region is substantially orthogonal, the optical path can be parallel-shifted in the two directions of XY. In other words, this configuration ensures 2
Light can be deflected in the dimension.

In FIG. 8, the first light deflection device 41
a, polarization plane rotation means 42, and second light deflection device 41b
Are shown to be spaced apart from each other, but in practice it is preferred that the elements be placed in contact. As the polarization plane rotation means 42, 1/2
A wave plate or a twisted nematic (TN) cell can be used. For example, in the case of a TN cell, after forming an alignment film on a glass substrate, an alignment treatment such as rubbing is performed to form a cell so that the alignment directions are orthogonal to each other, and nematic liquid crystal is injected.

FIG. 9 is a view for explaining the rotation action of the plane of polarization by the TN cell, in which 50 is a TN cell.
51 and 52 are substrates, L _TN is twisted nematic (TN)
It is a liquid crystal. As shown in FIG. 9, by arranging the substrate 51 on the incident side so that the orientation direction thereof coincides with the polarization direction of the incident light, the light transmitted through the TN cell 50 becomes the emitted light with the polarization plane rotated by 90 degrees. . In this case, since it is not necessary to drive the TN cell 50 with an electric field, a transparent electrode is not required and the structure is simple. Further, by sharing the substrate of the light deflection element and the substrate of the TN cell, it is possible to reduce the number of substrate interfaces and reduce the loss of light utilization efficiency due to interface reflection.
Corresponding to).

(Embodiment 1) FIG. 10 is a diagram for explaining an example in which the optical element (light deflecting element) of the present invention is specifically embodied, and the optical element is formed by changing the direction of the alignment treatment. An example is shown in FIGS. 10 (A) to 10 (C). In FIG. 10, 60 is an optical element, and 61 and 62 are I.
A glass substrate with TO, 63 is a spacer, and R is the orientation processing direction. First, I with a size of 3 cm × 3 cm and a thickness of 3 mm
The glass substrates 61 and 62 with TO were washed, and a polyimide orientation agent AL3046 was applied to a thickness of about 800Å. The substrate surface is shown in FIG. 10 (A), FIG. 10 (B) and FIG.
The rubbing alignment treatment was performed in the three types of directions (C) so that the alignment treatment directions R of the substrates 61 and 62 were the same direction (parallel direction).

Next, a spacer 63 having a thickness of 37 μm is arranged on and bonded to a part of the substrates 61 and 62, and three kinds of wedge-shaped liquid crystal cells having an inclination angle between the substrates of 0.2 ° (see FIG. 10).
(A) to FIG. 10 (C)) were produced. And substrate 6
In the state where 1, 62 are heated to 90 ° C., two substrates 61,
Between 62, a ferroelectric liquid crystal (CS1029 manufactured by Chisso) having a cone angle of 50 ° was injected by a capillary method. After slowly cooling and sealing with an adhesive, the alignment state of the ferroelectric liquid crystal was observed with a polarization microscope. As a result, uniform alignment was obtained in all rubbing directions in the portion where the liquid crystal layer thickness was 6 μm or less.

Then, a voltage of 10 V was applied to the above three types of cells having different orientation treatment directions R, and the angle of the bistable state was measured. The measurement direction was switched between two stable states with different polarities, and the angle between the two directions that minimizes the transmittance between the crossed Nicols was obtained. It was found that the stable state of all three types of liquid crystal cells was at a position of 25 ° to the left and right from the rubbing direction R, and even in the wedge cell of the ferroelectric liquid crystal, the bistable direction could be controlled by the parallel rubbing direction.

(Comparative Example 1) FIG. 11 is a diagram for explaining a comparative example of the optical element according to the present invention. FIG. 11 shows an example in which the optical element is formed by changing the direction of the alignment treatment.
It is shown in (A) to FIG. 11 (C). In FIG. 11, R1 is an alignment treatment direction on the first substrate (upper substrate) 61 side, R2 is an alignment treatment direction on the second substrate (lower substrate) 62 side, and has the same functions as those in FIG. The parts are given the same reference numerals as in FIG.

In this comparative example, FIG. 11 (A) and FIG.
As shown in (B) and FIG. 11 (C), the treatments were performed so that the orientation treatment directions R1 and R2 by rubbing crossed each other. Other processes were the same as in Example 1, and three types of liquid crystal cells shown in FIGS. 11A to 11C were manufactured. When the state of alignment was observed with a polarizing microscope after injecting the liquid crystal, streak-like defects were generated and the alignment was non-uniform in all of the three types of liquid crystal cells even when the liquid crystal layer thickness was 6 μm or less.

Further, two stable state angles were measured in the same manner as in Example 1 by using the portions of the above-mentioned three kinds of liquid crystal cells with the orientation as uniform as possible, but the transmittance was minimized depending on the portion to be measured. It was found that the bistable states were not obtained because the angles in the two directions were different.

Example 2 FIG. 1 produced in Example 1 above.
Using a cell of 0 (A), laser light was made incident on a portion where the liquid crystal layer thickness of the cell was 5 μm, the liquid crystal molecules were switched at ± 15 v, and the shift amount on the emission side CCD surface was measured. Orientation processing direction R by rubbing the polarization direction of incident light
However, the optical path was not shifted. However, when the polarization direction of the incident light was shifted to a position of 10 ° from the alignment treatment direction R, it was about 0.5 at a distance of 1 m.
An optical path shift of mm was obtained. However, there was a noise light component such as an afterimage at two shift positions of the optical path, and the contrast was relatively small.

Example 3 FIG. 10 produced in Example 1
Using the cells of (B) and FIG. 10 (C), a laser beam is made incident on a portion where the liquid crystal layer thickness of these cells is 5 μm, the liquid crystal molecules are switched at ± 15 v, and the shift amount on the emission side CCD surface is adjusted. Was measured. The polarization direction of the incident light was aligned with one stable direction of the liquid crystal molecules. In each case, a relatively large optical path shift of about 0.8 mm could be confirmed at a distance of 1 m. However, there was a noise light component such as an afterimage in one of the two shift positions in the optical path, and the contrast was relatively small.

(Embodiment 4) With the same construction as in Embodiment 3, a polarizing plate was installed on the outgoing light side. Although the optical path shift amount did not change, the noise light component was removed and the contrast was improved. However, the amount of light was slightly reduced by installing the polarizing plate.

Example 5 A liquid crystal material having a cone angle of 8
A 6 degree ferroelectric liquid crystal (CS2005 manufactured by Chisso) was used, and cells were prepared in the same manner as in Example 1 and Example 3 except for this. Laser light was made incident on a portion of the obtained cell having a liquid crystal layer thickness of 5 μm, the liquid crystal molecules were switched at ± 15 v, and the shift amount on the emission side CCD surface was measured. The polarization direction of the incident light was aligned with one stable direction of the liquid crystal molecules. In each case, a relatively large optical path shift of about 0.8 mm could be confirmed at a distance of 1 m. In this case, the noise light component at the two shift positions of the optical path was very small, and the contrast was relatively large.

(Embodiment 6) A quartz glass substrate having a size of 3 cm × 3 cm and a thickness of 1 mm is dry-etched, and the tilt angle (the tilt angle with respect to the reference surface when the substrate surface before etching is used as the reference surface) is about. 0.5 °, pitch 100 μm
After forming a sawtooth shape of 1 cm × 1 cm in area, ITO was sputtered on the sawtooth surface to a thickness of 2000 Å. Next, a polyimide alignment agent AL3046 is applied to a thickness of about 800 Å, and the substrate surface is aligned by a rubbing method under the condition that one stable state in the bistable homogeneous direction is perpendicular to the inclination direction of the inclined region. Processed. The glass substrate with ITO having a smooth surface was used as a counter substrate, and the glass substrate was bonded using an adhesive agent in which beads were mixed so that a portion having a small liquid crystal layer thickness was 3 μm. Then, while the substrates were heated to 90 degrees, a ferroelectric liquid crystal similar to that in Example 5 was injected between the two substrates by a capillary method, and after cooling, sealing was performed.
Observation of the alignment state shows a sawtooth shape of 1 cm x 1 cm
The portion of was in a substantially uniform alignment state.

Laser light is made incident on the above liquid crystal cell,
Switching of liquid crystal molecules at 15v and CC on the output side
The shift amount on the D surface was measured. The polarization direction of the incident light was perpendicular to the tilt direction of the sawtooth shape. When the sawtooth-shaped portion was measured at five points diagonally, the optical path shift amount was 0.8 mm at all points. A uniform optical path shift amount was obtained in a wide range.

(Embodiment 7) FIG. 12 is a diagram for explaining an embodiment of an image display device to which the light deflection element according to the present invention is applied. In the drawing, 70 is an image display device, 71 is a light source, and 72 is A diffusion plate, 73 is a condenser lens, 74 is a transmissive liquid crystal panel as a display element, 75 is a projection lens as an optical member for observing an image pattern, 76 is a screen, 77 is a light source drive unit for a light source, 78
Is a liquid crystal drive unit for the transmissive liquid crystal panel, 79 is a drive unit of the light deflection unit, and 80 is a light deflection unit.

In the traveling direction of the light emitted from the light source 71 in which the LED lamps are arranged in a two-dimensional array toward the screen 76, the diffusion plate 72, the condenser lens 73, the transmissive liquid crystal panel 74 as an image display element, the image A projection lens 75 as an optical member for observing the pattern is sequentially arranged. An optical deflector 80 functioning as a pixel shift element is interposed on the optical path between the transmissive liquid crystal panel 74 and the projection lens 75, and is connected to the drive unit 79. As the light deflecting means 80, the light deflecting device or the light deflecting device according to the present invention as described above can be preferably used.

The light source 71 is controlled by the light source drive unit 77.
The illuminating light emitted from the illuminating device becomes uniform illuminating light by the diffusion plate 72, and is controlled by the condenser lens 73 by the liquid crystal drive unit 78 in synchronization with the illuminating light source to critically illuminate the transmissive liquid crystal panel 74. The illumination light spatially light-modulated by the transmissive liquid crystal panel 74 is incident on the light deflecting unit 80 as image light, and the image deflecting unit 80 shifts the image light in the pixel arrangement direction by an arbitrary distance.
This light is magnified by the projection lens 75 and projected on the screen 76.

By displaying an image pattern in which the display position is displaced according to the deflection of the optical path for each of a plurality of subfields obtained by temporally dividing the image field by the light deflecting means 80, the transmissive liquid crystal is displayed. The apparent number of pixels of the panel 74 is multiplied and displayed. In this way, the shift amount by the light deflecting means 80 is set to 1/2 of the pixel pitch because image multiplication is performed twice in the pixel arrangement direction of the transmissive liquid crystal panel 74. By correcting the image signal for driving the transmissive liquid crystal panel 74 according to the shift amount by the shift amount, an apparently high-definition image can be displayed. At this time, since the light deflecting device or the light deflecting device as in each of the above-described embodiments is used as the light deflecting means 80, the utilization efficiency of light is improved, and the observer can observe the light without increasing the load on the light source. It can provide bright and high quality images.

Incidentally, an example of a light deflecting means for a pixel shift element incorporated in a conventional image display device (Japanese Patent Laid-Open No. 6-58242).
(Proposed example of JP-A-324320) is shown. The optical element as the light deflecting means is an element for shifting the light at two positions in the horizontal and vertical directions and a total of four positions (two-dimensional four-point pixel shift), and a crystal phase modulation made of a ferroelectric liquid crystal or the like. The combination of the element and the birefringent medium consisting of an electro-optical element is horizontal
Each set consists of two sets for the vertical direction.

In the conventional image display device using this optical element, since this optical element achieves the light deflection by the combination of (1) the crystal phase modulation element and the birefringent medium, the light loss at this interface is However, similarly, (2) there is a problem that the contrast is likely to be lowered due to light scattering at the interface, and (3) the cost is high because the electro-optical element for the birefringent medium is expensive. The image quality obtained was not good, and the device cost tended to increase significantly. In this respect, in the case of the configuration of the light deflection unit 80 of the present embodiment, these factors can be eliminated as described above in each embodiment, so that the occurrence of image deterioration due to the alignment defect of the light deflection element can be suppressed. And the image quality is good,
It is also advantageous in terms of cost.

FIG. 13 is a diagram for explaining an embodiment of an image display device according to the present invention which uses a reflective liquid crystal panel as an image display element. In the figure, 81 is a reflective liquid crystal panel.
Reference numeral 82 denotes a polarization beam splitter, and other parts having the same functions as those in FIG. 12 are denoted by the same reference numerals as those in FIG.
The image display device 90 is not limited to the type in which the transmissive liquid crystal panel 74 is used for the image display element as shown in FIG. 12, and is also the type in which the reflective liquid crystal panel 81 is used as shown in FIG. Applicable to In this case, a polarization beam splitter (PBS) 82 is added as compared with the image display device 70 shown in FIG. 12, and the light from the illumination system is reflected by the PBS 82 toward the reflective liquid crystal panel 81 side, and the light deflecting means 80 is turned on. Through the reflective liquid crystal panel 81
Is irradiated. Illumination light that has entered the reflective liquid crystal panel 81 is reflected by a reflector (not shown) provided on the rear surface of the liquid crystal panel.
While being reflected by, it undergoes spatial modulation corresponding to the image and is emitted as image light. After that, the light enters the light deflection unit 80, and the image light is shifted by a predetermined distance in the pixel arrangement direction by the light deflection unit 80. The subsequent route is shown in Figure 12.
This is similar to the case of the transmissive liquid crystal panel 74 shown in FIG.

[0076]

As is apparent from the above description, according to the present invention, in an optical element including a liquid crystal cell using a chiral smectic C layer and having a non-parallel substrate spacing, a ferroelectric liquid crystal having a ferroelectric liquid crystal within a tilt region is used. It is possible to provide a method for forming a bistable homogeneous alignment state in a direction, and to provide an optical element, a light deflecting element, a light deflecting device, and a light deflecting device capable of performing high-speed optical path shift with a simple configuration.

That is, by performing the alignment treatment so that the liquid crystal molecule alignment directions are in the same plane, a bistable homogeneous alignment state can be obtained even in the inclined region, and the yield at the time of manufacturing the element due to the alignment failure can be obtained. It is possible to improve the life of the device. Further, when the bistable homogeneous orientation directions are arranged so as to be asymmetric with respect to the direction of the incident linearly polarized light, the refractive index changes, and the function of optical path shift capable of high-speed response is obtained.

The optical paths can be parallel-shifted by making the inclined regions of the pair of optical deflection elements face each other. A light deflection device can be provided. In addition, two optical path deflecting devices capable of deflecting in one direction are combined and arranged so that the maximum inclination directions of both inclined regions are rotated by 90 degrees, and the polarization plane of the light emitted from the incident side optical deflecting device is changed. It is possible to provide an optical deflecting device capable of surely deflecting light in a two-dimensional direction by rotating it by 90 degrees and making it enter the second optical deflecting device. Further, by applying the optical deflecting device or the optical deflecting device as described above to the image display device, it is less likely that the image deterioration based on the alignment defect of the optical deflecting element occurs as compared with the conventional case.
It becomes possible to obtain stable image quality.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a deflection operation due to a change in refractive index on an inclined surface of a substrate.

FIG. 3 is a diagram for explaining an alignment direction suitable for realizing stable operation of liquid crystal molecules.

FIG. 4 is a schematic front view of an embodiment in which the alignment state of liquid crystal molecules is optimized in the light deflection element according to the present invention, and is a diagram schematically showing a liquid crystal cell of the light deflection element.

FIG. 5 is a diagram for explaining another embodiment of the present invention.

FIG. 6 is a diagram for explaining an embodiment of the optical deflecting device according to the present invention, and is a diagram for explaining an operation when the inclined regions of the optical element are arranged to face each other.

FIG. 7 is a schematic view for explaining another embodiment of an optical deflecting device having a configuration in which a pair of sawtooth substrates are arranged to face each other.

FIG. 8 is a schematic perspective view for explaining an embodiment of a light deflecting device according to the present invention.

FIG. 9 is a diagram for explaining the rotation action of the polarization plane by the TN cell.

FIG. 10 is a diagram for explaining an example in which the optical element (optical deflection element) of the present invention is specifically embodied.

FIG. 11 is a diagram for explaining a comparative example of the optical element according to the present invention.

FIG. 12 is a diagram for explaining an example of the image display device to which the light deflection element according to the present invention is applied.

FIG. 13 is a diagram for explaining an example of an image display device according to the present invention using a reflective liquid crystal panel as an image display element.

[Explanation of symbols]

1, 1 ', 1 "... Optical deflection element, 2 ... Transparent electrode, 3, 4 ...
Substrate, 5 ... Spacer, 6 ... Alignment film, 7 ... Liquid crystal layer, 10 ...
Rubbing direction indicating arrow, 11 ... Optical deflector, 13, 14
... substrate, 15 ... spacer, 17 ... liquid crystal layer, 21 ... optical deflection device, 23, 24 ... substrate, 27 ... liquid crystal layer, 28 ... intermediate substrate, 31 ... optical deflection device, 33, 34 ... substrate, 3
7 ... Liquid crystal layer, 38 ... Intermediate substrate, 41a ... First light deflecting device, 41b ... Second light deflecting device, 42 ... Polarization plane rotating means, 43 ... Polarization plane rotating means, 50 ... TN cell, 5
1, 52 ... Substrate, 60 ... Optical element, 61, 62 ... ITO
Attached glass substrate, 63 ... Spacers, 70, 90 ... Image display device, 71 ... Light source, 72 ... Diffusion plate, 73 ... Condenser lens, 74 ... Transmissive liquid crystal panel, 75 ... Projection lens,
76 ... Screen, 77 ... Light source drive section, 78 ... Liquid crystal drive section, 79 ... Light deflection means drive section, 80 ... Light deflection means, 81 ... Reflective liquid crystal panel, 82 ... Polarization beam splitter, L ... Liquid crystal molecule, R , R1, R2 ... Orientation processing direction, T ₁ ... First inclined region, T ₂ ... Second inclined region, T
₃ ... third inclined area, T ₄ ... fourth inclined region, the maximum inclination direction in the T _L ... inclined region, L _TN ... twisted nematic (TN) liquid crystal.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Saiki Tokita             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Yasuyuki Takiguchi             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Emura Nimura             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Masanori Kobayashi             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H049 BA02 BA06 BA42 BB03 BB62                 2H088 EA45 EA47 GA04 GA17 HA03                       HA15 HA18 JA11 JA17 KA15                       MA18                 2K002 AA01 AB04 BA06 CA14 DA14                       EA30 HA02

Claims (14)

[Claims] 1. A liquid crystal cell in which two substrates each having a transparent electrode film and a liquid crystal alignment film, and a liquid crystal layer in which liquid crystal molecules are aligned in a predetermined direction on the liquid crystal alignment film are sealed between the substrates. The liquid crystal cell has an inclined region in which the two substrates are arranged at a predetermined inclination angle, and the liquid crystal layer is bistable in two directions in the inclined region. An optical element having a chiral smectic C phase having a homogeneous alignment state, wherein the alignment directions of the liquid crystal molecules on each of the liquid crystal alignment films in the inclined region are in the same plane. 2. An optical deflecting element capable of deflecting a traveling direction of incident linearly polarized light by using the optical element according to claim 1, wherein each orientation direction of the bistable homogeneous orientation is the incident direction. An optical deflection element, which is installed so as to be asymmetric when the polarization direction of linearly polarized light is the central axis. 3. The optical deflection element according to claim 2, wherein
The direction of the alignment treatment is set so that one stable direction of the bistable homogeneous alignment matches a plane including a direction perpendicular to the maximum tilt direction in the tilt region. element. 4. The light deflection element according to claim 2 or 3, wherein the polarization direction of the incident linearly polarized light is arranged so as to coincide with one stable direction of the bistable homogeneous alignment. Light deflection element. 5. The optical deflector according to claim 2, wherein a polarizing plate is provided on the exit side of the liquid crystal cell. 6. The optical deflection element according to claim 2, wherein
The angle between the two directions of the bistable homogeneous orientation is substantially a right angle, and the polarization direction of the incident linearly polarized light is arranged to be parallel to one stable direction of the bistable homogeneous orientation. And a light deflection element. 7. The optical deflection element according to claim 5, wherein
An optical deflection element, wherein a direction of alignment treatment is set so that one stable direction of the bistable homogeneous alignment matches a direction perpendicular to a maximum tilt direction in the tilt region. 8. The optical element according to claim 1, wherein a periodic structure having a sawtooth-shaped cross section is provided on the inner surface of one of the substrates, so that the inclined region is formed by one side of the sawtooth shape. An optical element characterized in that the inclined regions are macroscopically and continuously formed by a periodic structure having a shape. 9. The optical deflection element according to claim 2, wherein a periodic structure having a sawtooth-shaped cross section is provided on the inner surface of one of the substrates, and the tilt is formed by one side of the sawtooth-shaped structure. A light deflection element, wherein a region is formed, and the inclined region is macroscopically continuously formed by the saw-toothed periodic structure. 10. An optical deflecting device having a pair of the optical deflecting elements according to claim 1, wherein the first deflecting element is provided in the inclined region with respect to a traveling direction of incident light. The refracted light is incident on the inclined region of the second optical deflection element installed at a constant interval,
When the light is refracted again in the inclined region of the optical deflecting element and emitted, the deflected light emitted in accordance with each orientation direction of the bistable homogeneous orientation is emitted as parallel light so that the first inclined region The optical deflection device is characterized in that the arrangement angles of the substrate surface for deflecting the optical path and the substrate surface for deflecting the optical path in the second inclined region with respect to the incident light are set. 11. The optical deflection device according to claim 10, wherein a substrate surface for deflecting an optical path in the first inclined region and a substrate surface for deflecting an optical path in the second inclined region are parallel to each other. An optical deflection device characterized by being set as follows. 12. The optical deflecting device according to claim 10, wherein the first optical deflecting element and the second optical deflecting element are one substrate constituting one optical deflecting element. An optical deflection device, characterized in that it is configured to be shared. 13. A first light deflecting device according to claim 10, and a polarization plane rotating means for rotating the polarization plane of the emitted light of the first light deflecting device substantially at right angles. The second light deflection device according to any one of claims 10 to 12, wherein the outgoing light after the polarization plane is rotated by the polarization plane rotation means is incident, and the tilted area of the first light deflection device is provided. The optical deflecting device, wherein the maximum inclination direction and the maximum inclination direction of the inclination region of the second optical deflection device are arranged so as to be substantially orthogonal to each other. 14. An image display device in which a plurality of pixels capable of controlling light according to image information are two-dimensionally arranged, a light source for illuminating the image display device, and an image pattern displayed on the image display device. 13. The light according to claim 10, wherein an optical member for observing and an optical path between the image display element and the optical member are deflected for each of a plurality of subfields obtained by temporally dividing the image field. An image display device, comprising: a deflection device or a light deflection unit according to claim 13.