JP2003091013A - Liquid crystal device, optical deflection element, picture display device using the optical deflection element, method for manufacturing optical deflection element and method for driving the optical deflection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a liquid crystal device applicable to a picture display device which carries out a display by increasing the apparent number of pixels of a picture display element to twice its true number, to suppress lowering of the utilization factor of the light and to attain a picture display with high quality. SOLUTION: The liquid crystal device is provided with a liquid crystal layer 2 of which the distribution of refractive indexes is controlled with voltage application between two sheets of transparent substrates 1 with a comb shaped electrode array 3 formed thereon and an optical path deflection driving means 5 which varies a state of voltage application to the comb shaped electrode array 3 and a Fresnel lens is obtained by controlling the applied voltage. The liquid crystal layer 2 contains a polymer polymerized and hardened by a polymerizing and hardening agent, and a liquid crystal. In driving the liquid crystal with the voltage application, the liquid crystal is reoriented by the electric field so that the first stable state with no applied electric field is shifted to the desired second state. In recovering the orientation of liquid crystal molecules from the second state to the first state in driving, response speed of the element with the liquid crystal layer construction is far and away improved compared with the case the recovering of the orientation of the liquid crystal molecules is carried out only with alignment controllability of an alignment layer.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a liquid crystal element, a light deflection element, an image display device using the light deflection element, a method of manufacturing the light deflection element, and a method of driving the light deflection element, more specifically. Can be applied to an image display device that displays an image by multiplying the apparent number of pixels of the image display element. By performing high-speed switching on the order of microseconds, it is possible to suppress deterioration of light utilization efficiency and display a high-quality image. The present invention relates to a light deflection element capable of performing.

[0002]

2. Description of the Related Art Conventionally, as an optical interconnection element of an optical coupler, a distributed index type flat plate microlens using an ion exchange technique, a Selfoc lens, a diffractive type micro Fresnel lens, and a microsphere have been used. Various microlenses such as microlenses have been developed and used. Since these microlenses are made of a solid material such as glass, the optical characteristics of the lens itself are fixed and cannot be changed.

A liquid crystal microlens using a liquid crystal material as an optical material is known as an element (hereinafter referred to as an optical deflecting element) capable of changing a focal length or an optical path which is an optical characteristic of a single microlens. This liquid crystal microlens is arranged such that the liquid crystal layer is sandwiched between two glass substrates on which hole pattern electrodes having holes are formed in the regions to be the lens parts, and the hole parts of the electrodes of each glass substrate face each other. It has been configured. In this liquid crystal microlens, liquid crystal molecules are aligned along a nonuniform electric field that is generated in the hole portion inside the liquid crystal cell and is substantially symmetrical to an axis (optical axis) passing through the center of the hole. A refractive index distribution is generated by the orientation of liquid crystal molecules in the hole portion, and a lens effect is obtained. The refractive index distribution state at this time is almost a square distribution, and good lens characteristics are obtained.

As the liquid crystal microlens as described above, there is one using a nematic liquid crystal. With this nematic liquid crystal, the refractive index distribution in the hole portion can be controlled by changing the voltage applied to the liquid crystal cell, and a variable focus characteristic in which the focus moves in the optical axis direction can be obtained.

In addition, there is a liquid crystal microlens using an ultraviolet curable liquid crystal. The ultraviolet curable liquid crystal shows the same liquid crystal characteristics as the above nematic liquid crystal before the ultraviolet curing, and becomes the same state as the polymer film after the ultraviolet curing. The one using this ultraviolet-curable liquid crystal utilizes its ultraviolet-curing property. That is, in the above-described microlens, when a voltage is applied, liquid crystal molecules are aligned along a non-uniform electric field that is substantially symmetrical to the axis passing through the center of the hole to generate a refractive index distribution, and after the molecular alignment is stabilized,
When irradiated with ultraviolet rays, the liquid crystal is polymerized and cured to be in a state similar to that of a polymer film, and the alignment state before irradiation with ultraviolet rays is maintained. After the alignment state is maintained by polymerization and curing, the liquid crystal characteristics are not exhibited, and the lens effect is maintained even when no voltage is applied.

A conventional example in which the response speed of a liquid crystal lens is increased by mixing a polymer and a liquid crystal will be introduced below. For example, Japanese Patent Application Laid-Open No. 11-142806 discloses "optical device".
Is the speedup of the liquid crystal lens using the hologram, not the one using the nonuniform electric field, and the driving method is different.
It is easy to change the focal length, but it is difficult to shift the focus in the direction perpendicular to the optical axis.

The "variable focus lens, variable focus diffractive optical element, and variable deflection angle prism" disclosed in Japanese Patent Laid-Open No. 11-64817 does not utilize a nonuniform electric field, but rather a difference in refractive index between a liquid crystal and a substrate interface. It is a liquid crystal lens that uses the shape of the substrate, and it is easy to change the focal length, but it is difficult to shift the focus in the direction perpendicular to the optical axis. Further, it is described that the speed is increased by mixing a polymer, but it is not specifically explained.

[Graded Index Type Liquid Crystal Mic
rolens Using Small Amount of Polymer '': Materials
Science Forum, Vols.308-311 (1999) pp.591-596 H.Ku
Sanagi et al., uses a circular liquid crystal microlens that utilizes an inhomogeneous electric field to produce 18 wt% of a photo-curable liquid crystal polymer.
%, A response speed of about 1 msec. Is achieved. However, speeding up to less than millisecond has not been achieved.

[0009]

As described above, in the liquid crystal lens, the focal length of the lens can be continuously changed by the applied voltage. However, in the conventional liquid crystal microlens, the liquid crystal layer in the state where no voltage is applied regulates the molecular orientation only by the orientation regulating force of the alignment film, and when driving by applying a voltage, the state in which the voltage is applied to the state in which no voltage is applied It has a drawback that the recovery time of liquid crystal molecules to the inside becomes extremely slow, being several seconds or more. As a method of solving the above-mentioned drawbacks, for example, a photo-curable liquid crystal polymer was used to increase the response speed of liquid crystal molecules.
Speeding up to less than millisecond has not been achieved. There are no reports of liquid crystal lenses with sub-millisecond response speed.

An application example of a liquid crystal lens that realizes a sub-millisecond response speed is a high-definition image display device using a pixel shift method. Pixel shifting method for pixels of the image display element (for example, JP-A-4-113308, JP-A-5-113308)
No. 289004 and Japanese Patent Laid-Open No. 6-324320) are methods for doubling the apparent pixels by swaying the pixels of the original image at a high speed that cannot be recognized by human eyes. It is a display method that has the characteristic that a high-definition image can be obtained.

For example, when a so-called field sequential system is adopted, in which an LED light source of RGB three colors is used as a light source and color display is performed by rapidly switching the colors of light irradiated on one liquid crystal panel, for example, in the case of image display. In order to perform color display at a frame frequency of 60 Hz, one frame is further divided into three colors, and therefore an image corresponding to each color is switched at 180 Hz. That is, by turning on / off the LED light source of the corresponding color in accordance with the display timing of the image of each color of the liquid crystal panel, the observer can see the full-color image. The above-described method is advantageous in improving the definition of an image and reducing the size of an apparatus because one liquid crystal panel may be prepared without using a color filter.

In the above arrangement, by disposing the liquid crystal microlens behind the liquid crystal light valve, the image light is shifted by an arbitrary distance in the pixel arrangement direction. By this shift, the number of pixels is doubled and a high-definition image is obtained. In order to double the pixel multiplication in the horizontal direction of the image, the pixel position is shifted by 120 Hz, and the display time of the subfield image is within 8.3 milliseconds. During this period,
Time required for switching the optical path (optical path switching time) Δ
t and the time when the liquid crystal panel can be used for image display. The longer the time that can be used for image display, the longer the LED emission time of the field-sequential method, and therefore the emission brightness of the LED can be reduced.
The burden on the light source is reduced. Therefore, it is preferable that the optical path switching time Δt is as short as possible, a high-speed optical path switching means is required, and a liquid crystal lens having a high-speed response of less than 500 μsec.

The present invention has been made in view of the above-mentioned circumstances, and is applicable to an image display device for displaying by multiplying the apparent number of pixels of an image display element, and high-speed switching on the order of microseconds is possible. By making it possible, a liquid crystal element that suppresses deterioration of light utilization efficiency and enables high quality image display,
An object of the present invention is to provide a light deflection element, an image display device using the light deflection element, a method of manufacturing the light deflection element, and a method of driving the light deflection element.

[0014]

According to a first aspect of the present invention, there are provided two substrates facing each other, a liquid crystal layer containing liquid crystal molecules and a polymer enclosed between the substrates, and each substrate. An electrode, an alignment film provided between the liquid crystal layer and the substrate,
A voltage control means for controlling a voltage applied to the electrodes, the electrodes provided on at least one substrate are array electrodes in which lines of the electrodes are formed at intervals on the array, The voltage control means is characterized in that the voltages are applied so that the voltage values applied to the adjacent electrodes of the array electrodes are different.

According to a second aspect of the present invention, there is provided a light deflection element which has a function of deflecting an optical path of incident light and is used by being applied to an image display device. The light deflection element can control light according to image information. A two-dimensionally arranged image display device, a light source and an illumination device for illuminating the image display device, an optical device for observing an image pattern displayed on the image display device, and an image field temporally divided. A plurality of subfields, and a light path deflecting means for deflecting the light path of the emitted light from each pixel by using the light path deflecting element, according to the deflection state of the light path for each subfield. In a light deflection element applied to an image display device for displaying an image pattern in a state in which the display position is displaced, the apparent number of pixels is multiplied and displayed. The child has two substrates arranged to face each other, an electrode array formed on at least one of the substrates corresponding to the pixel pitch, and a liquid crystal layer containing a polymer and liquid crystal sealed between the substrates. However, the optical path of incident light is deflected by controlling the electric field applied to the liquid crystal layer by the electrode array.

According to a third aspect of the invention, in the second aspect of the invention, the polymer contained in the liquid crystal layer is a polymer polymerized and cured by a polymerization curing agent.

According to a fourth aspect of the invention, in the third aspect of the invention, the polymerization curing agent is a photo-curing type.

The invention of claim 5 is characterized in that, in the invention of claim 3 or 4, the polymerized and cured polymer is a photocurable polymer having a liquid crystalline skeleton as a partial structure. is there.

According to a sixth aspect of the invention, in the fourth or fifth aspect of the invention, an electric field is applied so as to forcibly align the liquid crystal in the liquid crystal alignment direction determined in the voltage non-application state during actual use, It is characterized in that it is prepared by photocuring the polymer.

The invention of claim 7 is characterized in that, in the invention of claim 6, the liquid crystal alignment direction determined in the voltage non-application state during actual use is a direction parallel to the substrate. .

The invention of claim 8 is the invention of any one of claims 3 to 7, wherein the mixing ratio of the monomer or prepolymer to be polymerized and cured to obtain the polymer is 15 wt% to the constituent material of the liquid crystal layer. % Or more 50 wt%
It is characterized by being in the following range.

According to a ninth aspect of the present invention, in any one of the second to eighth aspects, the liquid crystal layer has a thickness of 20 μm.
It is characterized by being m or less.

According to a tenth aspect of the present invention, in the invention according to any one of the second to ninth aspects, the light deflection element has a driving means for driving the liquid crystal molecules of the liquid crystal layer, and the driving means is the The driving voltage of the liquid crystal molecules is 30 V / μm or less.

According to an eleventh aspect of the present invention, 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 and an illumination device for illuminating the image display element, and the image display element An optical device for observing the image pattern displayed on the display, a display drive means for forming an image field by a plurality of time-divided subfields, and a light deflection element for deflecting the optical path of light emitted from each pixel. By displaying the image pattern in which the display position is shifted according to the deflection state of the optical path for each subfield, the apparent number of pixels of the image display element is increased. In the image display device for displaying, the optical path deflecting means is an optical deflecting element according to any one of claims 1 to 10 and an electrode array included in the optical deflecting element in synchronization with the display driving means. It is obtained by; and a light path deflection drive means for changing the voltage applied state.

According to a twelfth aspect of the invention, in the invention of the eleventh aspect, the optical path deflecting means is arranged along a first pixel arrangement direction of the pixels with respect to a two-dimensional arrangement direction of the image display element pixels. 11. The first optical deflection according to claim 1, wherein the optical path of the incident image pattern can be deflected and / or the focal position of the image pattern to be condensed can be moved. The element and the second pixel array direction of the pixels, the optical path of the image pattern incident through the first light deflection element is deflected, and / or the image pattern is condensed. The optical deflection element according to any one of claims 1 to 10 capable of moving a focal position, further comprising: a direction of a plane of polarization of linearly polarized light from the first pixel array direction to the second pixel array direction. Can be rotated in the pixel array direction Light plane rotating means, it is obtained by said being disposed between the first optical deflecting elements and the second optical deflecting elements.

According to a thirteenth aspect of the present invention, there is provided a method of manufacturing an optical path deflecting element which has a function of deflecting an optical path of incident light and is used by being applied to an image display device, wherein the light can be controlled according to image information. An image display device in which a plurality of pixels are two-dimensionally arranged, a light source and an illumination device for illuminating the image display device, an optical device for observing an image pattern displayed on the image display device, and an image field for time. A display drive unit formed of a plurality of subfields that are divided into a plurality of subfields, and an optical path deflecting unit that deflects the optical path of the light emitted from each pixel by using the optical path deflecting element. A light deflection element applied to an image display device for displaying an image pattern whose display position is shifted according to In the method, the light deflecting element is prepared by preparing two substrates to be opposed to each other, forming an electrode array corresponding to a pixel pitch on at least one of the substrates, and a liquid crystal layer containing a polymer and a liquid crystal. It is characterized by being manufactured by encapsulating between the above substrates.

According to a fourteenth aspect of the present invention, in the thirteenth aspect, the polymer contained in the liquid crystal layer is a polymer polymerized and cured by a polymerization curing agent.

According to a fifteenth aspect of the invention, in the invention of the fourteenth aspect, a photo-curing type polymerization curing agent is used as the polymerization curing agent.

The invention of claim 16 relates to claim 14 or 1.
In the invention of Item 5, a photocurable polymer having a liquid crystal skeleton as a partial structure is used as the polymer.

The invention of claim 17 is the same as claim 15 or 1.
In the invention of Item 6, the polymer is photocured in a state in which an electric field is applied so as to forcibly align the liquid crystal in a liquid crystal alignment direction determined in a voltage non-application state during actual use. is there.

According to an eighteenth aspect of the invention, in the seventeenth aspect of the invention, the liquid crystal alignment direction determined in the voltage non-application state during the actual use is a direction parallel to the substrate. .

The invention of claim 19 relates to claims 14 to 1.
In the invention of any one of 8 above, the mixing ratio of the monomer or prepolymer to be polymerized and cured to obtain the polymer to the constituent material of the liquid crystal layer is 15 wt% or more and 50% or more.
It is characterized in that the range is less than or equal to wt%.

The twentieth aspect of the present invention provides the thirteenth to first aspects.
In the invention of any one of 9 above, the thickness of the liquid crystal layer is
The feature is that the thickness is 20 μm or less.

The invention of claim 21 relates to claims 2 to 10.
In the method of driving the liquid crystal molecules of the light deflecting element according to any one of items 1 to 5, the driving voltage in the driving unit that drives the liquid crystal molecules of the liquid crystal layer is 30 V /
It is characterized in that the thickness is not more than μm.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Liquid crystal element (optical deflecting element) of the present invention
An example will be described. The liquid crystal element according to claim 1 can function as a light deflection element. In the following embodiments, the terms will be used in a unified manner as the light deflection element. Figure 1
FIG. 3 is a diagram for explaining a schematic configuration of the optical deflecting element of the present invention, in which 1 is a transparent substrate, 2 is a liquid crystal layer, 3 is an electrode (comb-shaped electrode array), 4 is an alignment film, and 5 is a liquid crystal layer. Is an optical path deflection driving means for performing optical path deflection by controlling the electric field with respect to. FIG. 2 is a schematic diagram showing a configuration example of a comb-shaped electrode array applied as the electrode 4 of the light deflection element of the present invention.

The light deflection element of the present invention is obtained by a technique based on a liquid crystal microlens. As shown in FIG. 1, two transparent substrates 1 and at least one transparent substrate are used to form lenses. The electrodes 3 formed by the comb-shaped electrode array as shown in FIG. 2 and the liquid crystal layer 2 in which the refractive index distribution can be controlled by applying a voltage between the two transparent substrates 1
And optical path deflection drive means for changing the voltage application state to the electrode 3. The surface of the electrode 3 in contact with the liquid crystal layer 2 preferably has a function of aligning liquid crystal molecules. To provide the alignment function, a normal alignment film 4 such as polyimide used for TN liquid crystal, STN liquid crystal and the like can be used. The alignment film 4 is preferably subjected to rubbing treatment or photo-alignment treatment. Furthermore, an insulating film (not shown) may be provided on the surface of the transparent electrode. Optical path deflection driving means 5
By controlling the applied voltage of the comb-shaped electrode array by
A Fresnel lens can be obtained.

The material of the transparent substrate 1 is glass,
Plastic or the like can be used. The material of the electrode 3 in the comb-shaped electrode array is ITO, Cr,
Al or the like can be used. The electrode 3 is the transparent substrate 1 on the liquid crystal layer 2 side.
Install on top. In addition, when the transparent substrate 1 itself used has conductivity, the transparent substrate 1 can also be used as an electrode. The electrodes are formed in an array on at least one transparent substrate side.

The liquid crystal layer 2 is provided between the two transparent substrates 1 and contains at least a polymer polymerized and cured by a polymerization curing agent and a liquid crystal. For the liquid crystal layer 2, for example, a mixed system of a general nematic liquid crystal and a polymerizable or curable monomer or prepolymer is prepared, and the monomer or prepolymer is polymerized and cured to maintain the nematic liquid crystal in a desired alignment state. As described above (hereinafter referred to as the first state).

When the liquid crystal of the liquid crystal layer 2 is driven by applying a voltage to the electrode 3, the liquid crystal is re-aligned by the electric field and transits from the above-mentioned first state to the desired second state. In the case where the liquid crystal layer is configured to include the polymer and the liquid crystal as described above, and particularly to the configuration including the polymer and the liquid crystal polymerized and cured by the polymerization curing agent, the second state at the time of driving In the recovery of the alignment of liquid crystal molecules from the liquid crystal to the first state, the response speed of the liquid crystal layer structure is remarkably improved as compared with the case where the alignment of the liquid crystal is recovered by the regulating force of only the alignment film. be able to.

This is because the contact area between the liquid crystal and the polymer is wide,
This is because the alignment control force of the polymer with respect to the liquid crystal is strong, so that the response speed of the liquid crystal to the electric field can be significantly increased. In an image display device that displays an image by multiplying the apparent number of pixels of the image display element, the light deflection element can perform high-speed switching on the order of microseconds, thereby suppressing deterioration of light utilization efficiency and displaying a high-quality image. Can be possible.

As the above-mentioned monomer or prepolymer, the photo-curing type is excellent in terms of easiness of forming a device and wide selection range of materials, and there is a degree of freedom in curing conditions, and heat curing is preferable. Suitable for high-speed design compared to molds. By using the photo-curable material, the device can be manufactured only by irradiating light after the liquid crystal is injected into the device cell. Further, by controlling the light intensity and the curing time, it is possible to easily obtain a polymer structure suitable for speeding up, and thus it is expected that the speeding up will be significantly higher than that of a thermosetting polymer.

Further, the polymer formed of the monomer or prepolymer preferably has a liquid crystal element as a partial structure in order to increase the amount of change in refractive index and prevent clouding. FIG. 3 is a diagram schematically showing a model of a liquid crystal layer applicable to the present invention, in which the polymer P in which the liquid crystal element e exists in the polymer skeleton and the liquid crystal molecules 2L are aligned. . In the polymer P as described above, since the polymer skeleton has a liquid crystal substituent (liquid crystalline element e), the polymer skeleton portion is also oriented and refraction occurs when a voltage is applied and when it is not applied. The rate change can be increased, and a transparent device that is free from cloudiness during curing can be created.

When the photo-curable monomer or prepolymer is photo-cured as described above, the liquid crystal is aligned in the liquid crystal alignment direction determined by the voltage application in the actual use without applying a voltage. By photo-curing, it is possible to obtain a high-speed device having an increased alignment regulating force. That is, by directing the alignment direction of the liquid crystal to a predetermined non-electric field state, good light deflection can be achieved. The voltage non-application state described here refers to a state in which a voltage equal to or higher than a threshold voltage for changing the liquid crystal alignment direction is not applied, and not only a state in which no voltage is applied, but a bias voltage for high-speed switching, for example. Indicates a state in which is applied.

When the liquid crystal has a homogeneous orientation in the state where no voltage is applied, the long axis (when Δε is positive) or the short axis (when Δε is negative) of the liquid crystal is parallel to the transparent substrate 1. By photo-curing in a state where an electric field is applied in parallel with the substrate, the alignment regulating force is further increased and a high-speed device can be obtained. The strength of the applied electric field may be about the same as the electric field applied when the device is driven,
It is suitable to apply V / μm or more, preferably 2 V / μm or more. By setting the long axis of the liquid crystal to be parallel to the substrate, the change in the refractive index during driving is large, and the recovery time of the liquid crystal can be shortened.

As a prepolymer of the photocurable polymer having the above-mentioned liquid crystal skeleton as a partial structure, for example, a compound as shown in FIG. 4 can be mentioned, and the photocurable polymer applicable to the present invention. The prepolymer is not limited to these. Further, the content of the polymerizable and curable monomer or prepolymer in the liquid crystal material is set to 1
When it is 5 wt% or more, it is possible to secure a response of 500 μsec. Or less under a predetermined condition as shown in Example 1 described later, and it is possible to apply the light deflection element particularly to an image display device for displaying moving images, which is preferable. .

However, if the content of the above-mentioned monomer or prepolymer in the material of the liquid crystal layer is 50 wt% or more, the restraint of the movement of the liquid crystal by the polymer after polymerization becomes strong, and the change in the refractive index due to the electric field becomes small, which is sufficient. No effective pixel reduction effect can be obtained. As shown in FIG. 5 showing the evaluation results of the content of the monomer or the prepolymer and the lens effect, a sufficient refractive index change can be obtained by setting the content of the prepolymer to 50 wt% or less. Further, by mixing the monomer or prepolymer in an amount of 15 wt% or more with respect to the liquid crystal material, an even faster device can be obtained (described later in Example 1).

The material of the liquid crystal layer 2 preferably has a large birefringence Δn and a large dielectric anisotropy Δε. The thickness of the liquid crystal layer 2 is set according to the thickness of the spacer member between the transparent substrates 1, and the spacer member is preferably provided only in the peripheral portion of the liquid crystal layer 2 so as not to hinder the transmission of light. further,
The liquid crystal layer 2 needs to have a thickness of 20 μm or less in order to increase the response speed to 500 μsec. Or less, and more preferably 5 μm or less in order to realize low voltage driving. However, if the thickness of the liquid crystal layer is 1 μm or less,
Although the speed increases, it becomes difficult to uniformly control the gap between the substrates, which makes it difficult to manufacture the device. Therefore, by setting the thickness of the liquid crystal layer 2 to 20 μm or less, a device capable of high-speed switching for microseconds can be obtained. An example of evaluating the thickness of the liquid crystal layer 2 will be described later in Example 5.

The electric field at the time of driving the liquid crystal is 30 V.
/ Μm or less, and when driven with an electric field strength higher than this, the polymer structure is disturbed and problems due to scattering occur. The voltage to drive the light deflection element is 30 V / μm
The following can make the polymer structure of the device less likely to break. An example of evaluation of driving voltage and polymer structure will be described later in Example 2.

The operation of the optical deflector of the present invention will be described below. FIG. 6 is a diagram schematically showing the alignment state of the liquid crystal in the liquid crystal cell. FIG. 6A shows the liquid crystal alignment in the non-operating state by no electric field, and FIG. 6A shows the liquid crystal alignment (state) in the state where the first voltage is applied to the electrodes. 6B shows the liquid crystal orientation (referred to as state II) in the state where the second voltage is applied to the electrodes.
It is shown in (C). In FIG. 6, 1 is a transparent substrate, 2L is liquid crystal molecules, 3 is an electrode, and 10 is a liquid crystal cell.

As shown in FIG. 6A, in the state of no electric field, the liquid crystal molecules 2L are homogeneously aligned so as to be parallel to each other along the transparent substrate 1. In FIG. 6A, it is assumed that the liquid crystal molecules 2L are aligned so that the major axis direction of the liquid crystal molecules 2L is aligned with the horizontal direction of the paper. The lines of the electrodes 3 are formed in an array on the upper transparent substrate 1. In this state, the light 1 passing through the liquid crystal layer travels straight because it is not affected by the distribution of the refractive index depending on the alignment direction of the liquid crystal molecules. Although the electrode 3 of the lower transparent substrate 1 is formed on the entire surface, it may be formed as an array electrode symmetrical to the upper electrode 3.

State I in FIG. 6B shows the case where a voltage equal to or higher than the threshold value is applied only to the line of the shaded electrode 3. In the corresponding part of the electrode 3 to which a voltage is applied, the liquid crystal molecules 2L are aligned vertically to the surface of the transparent substrate 1 by the electric field, and in the corresponding part of the electrode 3 to which no voltage is applied, the liquid crystal molecules 2L are aligned horizontally to the transparent substrate 1. Leave. The distribution of the alignment direction due to the non-uniform electric field inside the liquid crystal cell causes a refractive index distribution for extraordinary light. Therefore, the light 1 passing through the liquid crystal layer is deflected as shown in the figure.

FIG. 7 is a diagram for explaining switching of the refractive index distribution in the liquid crystal cell shown in FIG. For example, when linearly polarized light having a polarization plane parallel to the paper surface is incident on the liquid crystal cell 10 shown in FIG. 6, the effective refractive index becomes smaller as the long axis of the liquid crystal molecules is aligned perpendicularly to the substrate.
When the voltage is applied in the state I shown in FIG. 6B, the refractive index distribution of the liquid crystal cell 10 with respect to the linearly polarized light is as shown by the solid line (state I) in FIG. Next, state I in FIG. 6 (C)
When the electrodes to which a voltage is applied are switched as shown by I, the alignment state of the liquid crystal molecules also changes, and the refractive index distribution changes as shown by the broken line (state II) in FIG. Therefore, the light 1 passing through the liquid crystal layer is deflected in a direction different from that in the state of FIG. In the above example, the control for switching the electrodes to which the voltage is applied is performed by the optical path deflection driving means 5 in FIG. However, in order to deflect the light, a gradient may be generated in the electric field in the liquid crystal layer. Therefore, the optical path deflection driving means 5 may be controlled so that the voltage is applied so that the magnitude (absolute value) of the applied voltage is different between adjacent electrodes of the array-like electrode or in units of a plurality of lines.

FIG. 8 is a view for schematically explaining a state in which the light emitted from the four pixels of the liquid crystal light valve is incident on the liquid crystal cell from the lower side of the paper, in which 10 is a liquid crystal cell and 11 is a liquid crystal cell. Is an incident side pixel, 12 is an incident light, 13 is an emitted light,
Reference numeral 14 is an emission side pixel. For example, when the liquid crystal cell 10 is in the above state I and the four incident side pixels 11 display the states (a), (c), (e) and (g) as the first sub-frames, respectively, The above-mentioned (a) and (c) and (e) and (g) are reduced by the solid line refractive index distribution shown in FIG. At this time, as indicated by the solid line in FIG. 8, the pixel pitch of the output side pixels 14 is not constant.

Next, when the electrodes to which the voltage shown in FIG. 6C is applied are changed over in accordance with the display timing of the second sub-frame, the refractive index distribution is changed over to the state II shown in FIG. Here, as the second subframe, (b)
When the states of (d), (f), and (h) are displayed, the reduced pixel moves to the position of the emission side pixel 14 shown by the broken line in FIG. That is, by switching the sub-frame from several tens of Hz to several hundreds of Hz, it is apparent on the liquid crystal cell (b) (a)
There are eight pixels arranged irregularly with (c), (d), (f), (e), (g), and (h). An example in which the light deflection element of the present invention is embodied and created will be described below.

Example 1 A liquid crystal microlens cell is
The chrome comb-shaped electrode array shown in FIG. 2 and a solid ITO electrode were used as the counter electrodes. The electrode width of chromium is 3 μm,
The pitch was 10 μm and the number of electrodes was 1000. As the alignment film, AL3046-R31 (manufactured by JSR Corporation) was formed by spin coating and subjected to alignment treatment by a roller rubbing device. In order to adjust the cell gap, a UV-curing adhesive was mixed with a 5 μm true sphere and applied by a coating robot so as not to cover the electrode array. Rubbing direction is 1 for both transparent substrates
The UV-curing adhesive was cured by stacking and laminating it so as to be 80 degrees (so that the orientation of the liquid crystal would be homogeneous).

As a liquid crystal layer, a prepolymer of a photocurable polymer having a liquid crystal skeleton as a partial structure was mixed with nematic liquid crystal (ZLI-2471, Merck & Co., Inc.) and injected into the cell by a capillary method. A mixture of (A), (D) and (G) of FIG. 4 was used as a prepolymer of the photocurable polymer having the liquid crystalline skeleton as a partial structure, and the respective ratios thereof were A: D: G = 48. : 48: 4. Also,
A photopolymerization initiator (IRG-651, manufactured by Ciba Geigy) was mixed at a ratio of 1 wt% with respect to the polymerizable mixed liquid crystal.
The prepolymer was irradiated with ultraviolet rays having an intensity of 20 mW / cm ² for 1 minute at room temperature without electric field to be polymerized. The prepolymer was evaluated by changing it from 0 to 20%.

FIG. 9 is a view showing the schematic arrangement of a measuring device for measuring the response speed of a liquid crystal microlens by laser diffracted light. In the drawing, 20 is a liquid crystal microlens, and 21 is a liquid crystal microlens.
Is a condenser lens, 22 is a photo diode, 23 is an oscilloscope, and L is laser light. The response speed of the liquid crystal microlens 20 is determined by irradiating the comb-shaped electrode (FIG. 2) of the liquid crystal microlens 20 with the laser light L having a wavelength of 633 nm to collect diffracted light that appears due to periodic modulation of the refractive index (lens effect). The response speed was determined by collecting the light with the lens 21, receiving a part of the light with the photodiode 22, converting it into a voltage, and observing the voltage change with the oscilloscope 23. That is, when the applied voltage is switched to deflect the optical path, the intensity of the instantaneous diffracted light becomes small, so that the intensity of the diffracted light is 1
The speed of recovery from 00% to change to 90% was defined as the response speed.

FIG. 10 is a diagram showing the voltage dependence of the response speed when the content of the monomer or prepolymer in the material of the liquid crystal layer is changed. When the content of the monomer or prepolymer is up to 5%, the response speed is the same as when the content is 0%. However, when the content is 10% or more, the response speed is on the order of μ seconds, and when the content is 15%, 500 μsec. The response speed is sufficiently high to withstand the display of moving images. From this result, it was confirmed that the light deflection element according to the present invention is extremely effective in terms of response speed.

Example 2 The cell of the liquid crystal microlens prepared in Example 1 was driven at 10 to 50 V / μm and observed with a microscope. The result is shown in FIG. Figure 1
As shown in Fig. 1, it was found that in an electric field larger than 30 V / μm, the polymer structure was disturbed and scattering was generated.
As a result, the voltage for driving the light deflection element is 30 V / μm.
It was confirmed that the optical deflector operating method set below is extremely effective.

(Example 3) In Example 1, the content of the photocurable prepolymer in the material of the liquid crystal layer was set to 15
%, And when irradiated with light, a polymer was polymerized while applying an electric field of 2 V / μm to the comb electrodes A and B in FIG. 2 parallel to the counter substrate. When the response speed was measured by the method described in Example 1, it showed a high-speed response of 100 μsec. (Measurement limit) or less and no electric field was applied (350 μse).
Compared with c.), we were able to achieve higher speed. As a result, a photo-deflection element manufacturing method of photo-curing in a state where an electric field is applied in parallel with the substrate, which is a liquid crystal alignment direction determined in a voltage non-application state during actual use, is extremely effective when photo-curing. It was confirmed that there is.

(Embodiment 4) FIG. 12 is a view for explaining an embodiment of the image display device according to the present invention, in which 31
Is a light source, 32 is a lighting device, 33 is an image display element, 34 is an optical path deflecting element, 35 is a projection lens, 36 is a screen,
37 is a light source drive means, 38 is a display drive means, 39 is an optical path deflection drive means, and 40 is an image display control circuit. The optical path deflecting element 34 is composed of a liquid crystal microlens described later, and is composed of the optical deflecting element 34 and the optical path deflecting driving means 39 which changes the voltage application state to the electrode array of the optical deflecting element in synchronization with the display driving means 38. Optical path deflecting means is configured.

As the image display element 33, a liquid crystal light valve having a TFT liquid crystal panel was used. The pixel pitch in the liquid crystal panel is about 10 μm in both length and width. Further, a field sequential system is adopted in which an LED light source of RGB three colors is used as the light source 31 and color display is performed by rapidly switching the colors of the light radiated to the one liquid crystal panel. Since the frame frequency of image display is 60 Hz and one frame is further divided into three colors, the images corresponding to the respective colors are switched at 180 Hz. The LED light source of the corresponding color is turned on according to the image display timing of each color of the liquid crystal panel.
By turning on / off, the observer can see a full-color image.

The liquid crystal microlens containing 20% of the prepolymer prepared in Example 1 was used as the light deflection element 34 and was installed immediately after the image display element 33 by the liquid crystal light valve, and the pixel position and the transparent electrode were set. The alignment of the lines was adjusted, and an observation experiment of color moving image display was conducted. The driving frequency of the voltage applied to the electrode line of the liquid crystal cell was switched in synchronism with the subfield image signal of the image display element 33 to switch the pixel as shown in FIG. When a diffuser plate having a thin diffuser layer was fitted to the exit side of the liquid crystal microlens and the diffused light on the exit surface was observed under magnification, a high-definition moving image with a pixel density in the lateral direction doubled was obtained.

In FIG. 12, the first liquid crystal macro lens 34a for deflecting the optical path in the left-right direction of the paper surface (that is, the horizontal direction of the screen) is arranged on the upstream side of the optical path, and is in the vertical direction of the paper surface (that is, the screen A second liquid crystal microlens 34b for deflecting in the vertical direction) is arranged on the downstream side of the optical path, and further, the first and second liquid crystal microlenses 34a,
A polarization rotating means 34c for rotating the plane of polarization of the incident linearly polarized light is arranged between 34b.

The first and second liquid crystal macro lenses 3
The deflection directions of 4a and 34b are arranged so as to correspond to the two directions of the pixel arrangement of the image display elements 33 which are arranged two-dimensionally. That is, generally, the pixel arrangement directions of the image display element 33 are arranged so as to be orthogonal to each other in the vertical and horizontal directions, so that the first and second optical path deflecting means 34a, 34a, The directions of the respective transparent electrode arrays and the directions of the alignment treatment of the liquid crystal layer are set so that the acting directions of 34c, that is, the optical path deflection directions are also orthogonal to each other.

In the polarization plane rotating means 34c, until the linear polarization direction of the light emitted from the first liquid crystal microlens 34a coincides with the optical path deflection direction of the second liquid crystal microlens 34b (90 in this embodiment). After being rotated, it is incident on the second liquid crystal microlens 34b.

(Example 5) In Example 1, the content of the prepolymer was fixed to 20%, and the amount of 5 in the UV-curable adhesive was fixed.
The gap was controlled by changing to a μm spherical ball and sandwiching a Mylar film (made by Teijin DuPont Film) at a position where it did not block light between the substrates. When the response speed was measured by the method of Example 1, the response speed became slower as the thickness of the liquid crystal layer increased, and as shown in FIG. 13, those having a thickness greater than 20 μm required 500 μsec. Or more. From this, it was confirmed that it is extremely useful when the thickness of the liquid crystal layer is 20 μm or less.

(Example 6) An alignment film AL was formed on two transparent substrates.
3046-R31 (manufactured by JSR Corporation) was formed by spin coating, and subjected to orientation treatment by a roller rubbing device. In order to adjust the cell gap, a UV-curing adhesive was mixed with a 5 μm true sphere and applied by a coating robot so as not to cover the electrode array. Both transparent substrates were stacked so that the rubbing direction was 180 degrees (so that the liquid crystal orientation was homogeneous), and the UV curing adhesive was cured and laminated.
As the liquid crystal, a prepolymer of a photocurable polymer was mixed with a nematic liquid crystal (ZLI-2471, Merck & Co., Inc.) and injected into the cell by a capillary method.

Sample 1: A photo-curable polymer prepolymer having a liquid crystal skeleton as a partial structure as a prepolymer (a mixture of A, D and G in FIG. 4, each ratio of which is A: D: G = 48). : 48: 4), and a photopolymerization initiator (IRG-651, manufactured by Ciba-Geigy) was mixed therein in an amount of 1 wt% with respect to the prepolymer. And 20mW /
The prepolymer was polymerized by irradiating with ultraviolet light having an intensity of cm ² for 1 minute at room temperature without electric field. This cell is referred to as Sample 1.

Sample 2: OPM55 (manufactured by ADELL), which is a normal photocurable polymer having no liquid crystal skeleton, was used as the prepolymer of the photocurable polymer, and this prepolymer was 20% of the liquid crystal layer material. The mixture was mixed as above and polymerized in the same manner as in Sample 1. The obtained cell is referred to as Sample 2. When the transmittance of the above Samples 1 and 2 was measured, it was 90% in Sample 1, but 60 in Sample 2.
%, And it was found that the light was scattered. This shows that it is effective that the polymer which is polymerized and cured is a photocurable polymer having a liquid crystal skeleton as a partial structure.

[0071]

As is apparent from the above description, according to the light deflecting element of the present invention, in the image display device for displaying by multiplying the apparent number of pixels of the image display element, the light deflecting element is By enabling high-speed switching on the order of seconds, it is possible to provide an optical deflection element capable of suppressing deterioration of light utilization efficiency and enabling high-quality image display. Also, by using a polymer liquid crystal in which a liquid crystal skeleton is added to the polymer skeleton as the liquid crystal layer material, the refractive index change can be increased to increase the amount of light deflection and the response speed can be significantly increased. You can do it. Further, by using the above-mentioned light deflection element, it is possible to provide an image display device capable of suppressing deterioration of light utilization efficiency and displaying a high quality image.

Further, according to the present invention, by using the above-mentioned light deflection element, it is possible to provide a video camera having a high light utilization efficiency and capable of obtaining a clearer image. Further, according to the present invention, it is possible to provide a switching device which can operate unpolarized light and can perform highly reliable switching by using the above-mentioned light deflection element.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a schematic configuration of an optical deflection element of the present invention.

FIG. 2 is a schematic diagram showing a configuration example of a comb-shaped electrode array applied as an electrode of the light deflection element of the present invention.

FIG. 3 is a diagram schematically showing a model of a liquid crystal layer applicable to the present invention.

FIG. 4 is a diagram showing an example of a photo-curable polymer prepolymer applicable to the present invention.

FIG. 5 is a table showing the content of a monomer or a prepolymer and the evaluation result of the lens effect.

FIG. 6 is a diagram schematically showing an alignment state of liquid crystals in a liquid crystal cell.

7 is a diagram for explaining switching of the refractive index distribution in the liquid crystal cell shown in FIG.

FIG. 8 is a diagram schematically illustrating a state in which light emitted from four pixels of a liquid crystal light valve enters a liquid crystal cell from the lower side of the paper.

FIG. 9 is a diagram showing a schematic configuration of a measuring device for measuring a response speed of a liquid crystal microlens by laser diffracted light.

FIG. 10 is a diagram showing voltage dependence of response speed when the content of the monomer or prepolymer in the material of the liquid crystal layer is changed.

FIG. 11 shows a liquid crystal microlens cell of 10 to 50 V.
9 is a table showing observation results when driven at / μm.

FIG. 12 is a diagram for explaining an embodiment of the image display device according to the present invention.

FIG. 13 is a table showing evaluation results of liquid crystal layer thickness and response speed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate, 2 ... Liquid crystal layer, 2L ... Liquid crystal molecule, 3 ... Electrode (comb-shaped electrode array), 4 ... Alignment film, 5 ... Optical path deflection drive means, 10 ... Liquid crystal cell, 11 ... Incident side pixel, 12 ... Incident Light, 13 ... Emitted light, 14 ... Emission side pixel, 20 ... Liquid crystal microlens, 21 ... Condensing lens, 22 ... Photodiode,
23 ... Oscilloscope, 31 ... Light source, 32 ... Lighting device,
33 ... Image display element, 34 ... Optical path deflecting element, 34a ... First liquid crystal macro lens, 34b ... Second liquid crystal macro lens, 34c ... Polarization rotating means, 35 ... Projection lens, 36 ...
Screen, 37 ... Light source driving means, 38 ... Display driving means, 39 ... Optical path deflection driving means, 40 ... Image display control circuit, L ... Laser light, 2L ... Liquid crystal molecule.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13 505 G02F 1/13 505 2H092 1/133 505 1/133 505 2H093 570 570 1/1334 1 / 1334 1/1335 510 1/1335 510 1/1337 1/1337 G03B 21/00 G03B 21/00 E (72) Inventor Yumi Matsuki 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Hiroyuki Sugimoto 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Saeaki Tokita 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Takiguchi Yasuyuki F-term in Ricoh Co., Ltd. 1-3-3 Nakamagome, Ota-ku, Tokyo (reference) 2H049 AA02 AA12 AA41 AA45 AA60 AA61 2H088 EA42 HA02 HA03 HA06 HA25 HA 28 2H089 HA04 HA10 JA01 JA04 TA02 TA04 TA07 TA11 2H090 LA01 LA04 LA14 MA02 MA07 MB14 2H091 FA07X FA29X FD06 FD25 2H092 GA14 PA02 PA06 PA07 PA11 PA13 QA15 RA03 RA10 2H093 NA79 NC90 NE03 NE04 NE06 NF11

Claims (21)

[Claims] 1. A pair of substrates arranged to face each other, a liquid crystal layer containing liquid crystal molecules and polymers enclosed between the substrates, electrodes provided on each substrate, and the liquid crystal layer and the substrate. An electrode provided on at least one of the substrates comprises an alignment film provided between them and a voltage control means for controlling the voltage applied to the electrodes, and the lines of the electrodes are formed on the array at intervals. The liquid crystal element is characterized in that the voltage control means applies different voltages to adjacent electrodes of the arrayed electrodes. 2. A function capable of deflecting an optical path of incident light,
An optical deflection element applied and used in an image display apparatus, comprising: 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 an illumination device. An optical device for observing an image pattern displayed on the image display element, a display drive unit for forming an image field by a plurality of time-divided subfields, and an optical path deflecting element for each pixel. And an optical path deflecting means for deflecting the optical path of the emitted light, and displaying an image pattern in which the display position is displaced according to the deflection state of the optical path for each subfield, so that the image display element is apparently displayed. In a light deflection element applied to an image display device that multiplies and displays the number of pixels, the light deflection element includes two substrates arranged to face each other and pixels on at least one of the substrates. Of the incident light by controlling the electric field applied to the liquid crystal layer by the electrode array, which has an electrode array formed corresponding to the switch and a liquid crystal layer containing polymer and liquid crystal sealed between the substrates. An optical deflection element characterized by performing optical path deflection. 3. The optical deflection element according to claim 2, wherein
The light deflection element, wherein the polymer contained in the liquid crystal layer is a polymer polymerized and cured by a polymerization curing agent. 4. The optical deflector according to claim 3,
The light deflection element, wherein the polymerization curing agent is a light curing type. 5. The light deflection element according to claim 3, wherein the polymerized and cured polymer is a photocurable polymer having a liquid crystal skeleton as a partial structure. . 6. The optical deflection element according to claim 4, wherein the electric field is applied so that the liquid crystal is forcibly aligned in a liquid crystal alignment direction determined in a voltage non-application state during actual use. An optical deflection element, which is made by photo-curing a polymer. 7. The optical deflection element according to claim 6,
The optical deflector according to claim 1, wherein a liquid crystal alignment direction determined in a voltage non-application state during actual use is a direction parallel to the substrate. 8. The light deflection element according to claim 3, wherein a mixing ratio of a monomer or a prepolymer to be polymerized and cured to obtain the polymer to a constituent material of the liquid crystal layer is 15 wt%. An optical deflection element characterized by being in a range of not less than 50 wt%. 9. The optical deflection element according to claim 2, wherein the liquid crystal layer has a thickness of 20 μm or less. 10. The light deflection element according to claim 2, wherein the light deflection element has a driving unit that drives liquid crystal molecules of the liquid crystal layer, and the driving unit includes the liquid crystal. An optical deflection element characterized in that a driving voltage of a molecule is 30 V / μm or less. 11. 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 and an illumination device for illuminating the image display element, and an image pattern displayed on the image display element. An optical device for observing an image field, a display driving means for forming an image field by a plurality of time-divided subfields, and an optical path deflecting means using an optical deflecting element for deflecting an optical path of light emitted from each pixel. And an image display device that displays an image pattern in which the display position is displaced according to the deflection state of the optical path for each subfield, thereby multiplying the apparent number of pixels of the image display element for display. The optical path deflecting means changes the voltage application state to the electrode array of the optical deflecting element according to any one of claims 1 to 10 in synchronization with the display driving means. An image display device, comprising: 12. The image display device according to claim 11, wherein the optical path deflecting unit is arranged along a first pixel array direction of the pixels with respect to a two-dimensional array direction of the image display element pixels. 11. The optical path of the incident image pattern can be deflected, and / or the focus position where the image pattern is focused can be moved.
And a deflection of the optical path of the image pattern incident through the first light deflection element along the second pixel array direction of the pixel, and / or The optical deflector according to any one of claims 1 to 10, which is capable of moving a focus position where the image pattern is condensed, and further, a direction of a plane of polarization of linearly polarized light is set to the first direction. Polarization plane rotating means capable of rotating from the pixel arrangement direction to the second pixel arrangement direction is arranged between the first light deflection element and the second light deflection element. Image display device. 13. A method of manufacturing an optical path deflecting element, which has a function of deflecting an optical path of incident light and is used by being applied to an image display device, comprising a plurality of pixels capable of controlling light according to image information. Image display elements arranged in a dimension, a light source and an illumination device for illuminating the image display element, an optical device for observing an image pattern displayed on the image display element, and a plurality of image fields temporally divided Display drive means formed in each subfield and optical path deflecting means for deflecting the optical path of the light emitted from each pixel by using the optical path deflecting element. In the method of manufacturing a light deflection element applied to an image display device, which displays an image pattern in a state of being shifted by multiplying the apparent number of pixels of the image display element for display. The light deflection element is prepared by preparing two substrates which are arranged to face each other, forming an electrode array corresponding to a pixel pitch on at least one of the substrates, and forming a liquid crystal layer containing a polymer and a liquid crystal between the substrates. A method for manufacturing an optical deflection element, which is characterized in that the optical deflection element is manufactured by encapsulating in 14. The method of manufacturing an optical deflecting element according to claim 13, wherein the polymer contained in the liquid crystal layer is a polymer polymerized and cured by a polymerization curing agent. Method. 15. The method of manufacturing an optical deflection element according to claim 14, wherein a photo-curing polymerization curing agent is used as the polymerization curing agent. 16. The method of manufacturing a light deflecting element according to claim 14, wherein a photocurable polymer having a liquid crystal skeleton as a partial structure is used as the polymer. Production method. 17. The method for manufacturing an optical deflection element according to claim 15, wherein a state in which an electric field is applied so as to forcibly align the liquid crystal in a liquid crystal alignment direction determined in a voltage non-application state during actual use. 2. A method of manufacturing a light deflection element, wherein the polymer is photocured. 18. The method according to claim 17, wherein the liquid crystal alignment direction determined in the voltage non-application state during actual use is a direction parallel to the substrate. Deflection element manufacturing method. 19. The method of manufacturing an optical deflection element according to claim 14, wherein a mixing ratio of a monomer or a prepolymer to be polymerized and cured to obtain the polymer to a constituent material of the liquid crystal layer is set. And 15 wt% or more and 50 wt% or less. 20. The method of manufacturing an optical deflecting element according to claim 13, wherein the liquid crystal layer has a thickness of 20 μm or less. 21. A method of driving an optical deflecting element for driving liquid crystal molecules of an optical deflecting element according to any one of claims 2 to 10, wherein a driving voltage in driving means for driving the liquid crystal molecules of the liquid crystal layer. Is 30 V / μm or less, a method of driving an optical deflecting element.