JP2004053994A - Light deflection element and image display device - Google Patents

Abstract

An optical deflecting element which has better liquid crystal alignment stability than an optical deflecting element using a conventional ferroelectric liquid crystal material and has a simpler configuration than an optical deflecting element using a conventional nematic liquid crystal. An element is provided.
The light deflecting element includes one or a plurality of liquid crystal cells that are arranged side by side to deflect and emit incident light. Each of the liquid crystal cells 31 includes a pair of transparent substrates 32, a liquid crystal layer 34 of nematic liquid crystal filled between the substrates 32, 32, and an electric field applied to the liquid crystal layer 34 in the plate surface direction of the substrate 32. A comb-shaped electrode 35 for deflecting the optical path of the light transmitted through the liquid crystal layer 34. An inclined surface 33 that is inclined with respect to the opposing surface of the other substrate 32 in accordance with the direction of light deflection and continuously appears in one direction is formed on at least one surface of the substrate 32 on the liquid crystal layer 34 side. .
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light deflecting element and an image display device.
[0002]
[Prior art]
Various devices using a liquid crystal material have been proposed as light deflecting elements for deflecting and emitting incident light. For example, the following are known.
[0003]
First, Japanese Patent Application Laid-Open No. 6-18940 proposes a light beam shifter including an artificial birefringent plate for the purpose of reducing light loss of an optical space switch. In such a technique, it is necessary to increase the thickness of the wedge-shaped transparent substrate in order to widen the transmitted light beam width. In particular, when the illumination light is not a parallel light beam, the optical system becomes large, and the light use efficiency decreases. Causes inconveniences such as
[0004]
Japanese Patent Application Laid-Open No. Hei 9-133904 proposes an optical deflection switch which can obtain a large deflection, has a high deflection efficiency, and can arbitrarily set a deflection angle and a deflection distance. . In such a technique, since an electric field is generated by a pair of electrodes, there is a problem in that, when the distance between the electrodes is wide, the electric field intensity distribution greatly changes depending on the position from the electrode, and the position dependence of the deflection amount occurs. For this reason, the width of the light beam that can be transmitted is limited. Further, since the electroclinical effect of the smectic A phase is used, there is a problem that a higher speed cannot be expected as compared with switching using spontaneous polarization such as a chiral smectic C phase.
[0005]
Japanese Patent Application Laid-Open No. 5-204001 proposes an optical deflecting device which can be driven at a low voltage and is made two-dimensional and compact. This holds liquid crystal having birefringence between a pair of transparent substrates, and a sawtooth lattice is formed on one of the transparent substrates. The held liquid crystal is homogeneously oriented in the direction of the sawtooth grating, and the refractive index of either the long axis or the short axis of the liquid crystal matches the refractive index of the material forming the sawtooth grating. However, similarly to the technique disclosed in Japanese Patent Application Laid-Open No. 6-18940, it is necessary to use a polarization rotation device for incident light, and there is a problem that the device becomes complicated and large.
[0006]
[Problems to be solved by the invention]
On the other hand, the present applicant has proposed an optical deflecting element using a liquid crystal composed of a chiral smectic C phase in order to solve these disadvantages of the prior art. According to this light deflecting element, it is possible to control high-speed light deflection by driving a liquid crystal having a chiral smectic C phase.
[0007]
However, it is difficult to uniformly align a liquid crystal composed of a chiral smectic C phase on a substrate, and fine control such as temperature control at the time of manufacturing is required.
[0008]
On the other hand, a technique of increasing the response speed by using a so-called two-frequency driving method or a polymer stabilized liquid crystal is known. As these driving methods, a voltage is applied between the substrates to change the alignment state of the liquid crystal. There is something. When these liquid crystals are applied, for example, to the technology disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-18940, or to the above-mentioned light deflecting element using a liquid crystal composed of a chiral smectic C phase, the rubbing direction that determines the initial alignment state is changed. In the direction of the sawtooth grating, the liquid crystal molecules are aligned homogeneously in the direction of the marking when no voltage is applied, and the liquid crystal molecules are homeotropically aligned with the substrate when the voltage is applied. Techniques for deflecting are conceivable.
[0009]
However, according to this principle of operation, when it is desired to deflect incident light in four directions, up, down, left and right, it is possible to use two or more liquid crystal cells. In addition, a liquid crystal cell using substrates having different rubbing directions for determining the initial alignment state of the liquid crystal is required. When a λ / 2 plate is used, the influence of the wavelength characteristics of the λ / 2 plate and the transmittance of light passing through the element are reduced, and the element configuration becomes complicated. Also, using a substrate in which the rubbing direction is changed with respect to the saw-toothed grid increases the number of production processes, which leads to a problem that productivity is reduced.
[0010]
It is an object of the present invention to provide a liquid crystal alignment stability that is superior to that of a conventional light deflecting device using a ferroelectric liquid crystal material, and that the configuration is simpler than that of a conventional light deflecting device that uses a nematic liquid crystal. It is to provide a light deflecting element that can be used.
[0011]
In order to achieve the above object, an inclined surface formed on a surface of at least one substrate of the liquid crystal cell on a liquid crystal layer side and inclined with respect to a facing surface of the other substrate in accordance with a direction of light deflection. When the surface is formed, it can be formed by photolithography, etching, or the like, but an array of concave and convex shapes of an inclined surface for obtaining a predetermined light deflection direction, particularly those with a small pitch and those with a large number of arrays Is difficult to form, and a problem may occur in the direction of light deflection due to the formed concavo-convex shape.
[0012]
For example, if the apex of the uneven shape has a gentle curved surface, the light incident on the apex will be condensed or scattered, and will be deflected in a direction different from the desired light deflection direction and leaked. Light is generated. Further, when there are two inclination angles, that is, a gentle inclination angle and a steep inclination angle, in the uneven shape, the light deflection is performed as the angle of the steep inclination angle becomes gentle (that is, the shape becomes closer to an isosceles triangle). Is deviated from the predetermined direction.
[0013]
Another object of the present invention is to achieve a predetermined deflecting direction by shielding leakage light traveling in a direction different from the predetermined deflecting direction when achieving the above-mentioned object.
[0014]
[Means for Solving the Problems]
The invention according to claim 1 includes one or a plurality of liquid crystal cells arranged so as to deflect and emit incident light, wherein each of the liquid crystal cells is filled with a pair of transparent substrates and filled between the substrates. A liquid crystal layer containing a nematic liquid crystal, an electrode for applying an electric field to the liquid crystal layer in a plate surface direction of the substrate to deflect an optical path of light transmitted through the liquid crystal layer, and at least one of the substrates on the liquid crystal layer side. And an inclined surface formed on a surface and inclined with respect to the opposite surface of the other substrate in accordance with the direction of the deflection.
[0015]
Therefore, the light incident on the liquid crystal cell is deflected due to the birefringence of the liquid crystal and the shape of the inclined surface of the substrate. Then, since a so-called lateral electric field drive is performed using a nematic liquid crystal for the liquid crystal layer, the alignment stability is good, and the same optical action as that of the optical deflection element using the ferroelectric liquid crystal can be obtained.
[0016]
Further, in the case where a plurality of liquid crystal cells are arranged and the light deflecting element is configured so that the deflecting direction of the emitted light becomes four directions, a liquid crystal is driven in a lateral electric field to form a substrate having an inclined surface in the light deflecting element. The rubbing direction to the substrate may always be the same as the shape of the inclined surface, and light can be deflected in four directions without a λ / 2 plate between the light deflecting elements. Can be made relatively simple and at low manufacturing cost.
[0017]
According to a second aspect of the present invention, in the optical deflecting element according to the first aspect, the nematic liquid crystal is a polymer stabilized liquid crystal.
[0018]
Therefore, since the alignment state of the liquid crystal is maintained by the polymer network, the alignment control force of the polymer with respect to the liquid crystal is strong, so that a high response speed of the liquid crystal can be obtained.
[0019]
According to a third aspect of the present invention, in the optical deflecting device according to the first aspect, the liquid crystal material of the nematic liquid crystal is a material whose dielectric anisotropy changes to positive or negative in accordance with the frequency of an applied voltage. It is.
[0020]
Therefore, since the so-called two-frequency driving liquid crystal, which can select the positive or negative of the dielectric anisotropy depending on the frequency, can be used to control the alignment state of the liquid crystal by switching the frequency, there is no need for a separate electrode for electrically returning to the initial alignment state. The electrode configuration is simple, and a faster response speed for returning to the initial alignment state with a weak rubbing control force can be obtained.
[0021]
According to a fourth aspect of the present invention, in the optical deflecting element according to any one of the first to third aspects, a light shielding member for shielding an optical axis overlapping the electrode is provided.
[0022]
Therefore, since the electric field that changes the alignment state of the liquid crystal hardly changes on the electrode, the alignment state of the liquid crystal hardly changes on the electrode, that is, on the electrode, without being affected by the birefringence of the liquid crystal. The light passing over the electrodes becomes leaked light without being deflected. However, since such leaked light can be shielded, an optical deflecting element having a uniform deflection direction can be configured.
[0023]
According to a fifth aspect of the present invention, in the optical deflecting element according to the fourth aspect, the inclined surface is a plurality of inclined surfaces continuously appearing in one direction, and the electrodes have polarities of an applied voltage alternately. A plurality of different parallel line-shaped electrodes, the length direction of which is parallel to the direction of the scribed line of the unevenness due to the continuation of the inclined surface, is formed at a leaked light position caused by the unevenness.
[0024]
Therefore, the light incident on the light deflecting element is deflected due to the birefringence of the liquid crystal and the shape of the inclined surface. If the part has a curved surface, a predetermined deflection direction cannot be obtained and light leakage will occur, but the length of the electrode is parallel to the direction of the scribed line of the unevenness due to the continuation of the inclined surface. Is formed at the leaked light position, the leaked light caused by the electrodes and the leaked light caused by the inclined surface shape can be shielded, and the leaked light that is not deflected is shielded, resulting in an optical deflection element having a uniform deflection direction. .
[0025]
According to a sixth aspect of the present invention, in the optical deflecting element according to the fourth aspect, the inclined surface is a plurality of inclined surfaces continuously appearing in one direction, and the light shielding member is formed by the continuation of the inclined surface. Leakage light generated from disorder of the liquid crystal alignment of the liquid crystal layer in the apex portion of the unevenness and the region between the inclined surfaces is shielded.
[0026]
Therefore, leakage light generated by disturbance of the liquid crystal orientation of the liquid crystal layer in the apex portion of the unevenness due to the continuation of the inclined surface and the region between the inclined surfaces is shielded, so that the leakage light absorbed by the disturbance of the liquid crystal and not deflected is absorbed. The light deflecting element is entirely shielded from light and has a uniform deflecting direction.
[0027]
The invention according to claim 7 is the optical deflection element according to any one of claims 1 to 6, wherein the inclined surface is a plurality of inclined surfaces that appear continuously in one direction, and the electrode includes: A plurality of parallel linear electrodes alternately having different polarities of the applied voltage, and are formed in a light transmitting region other than causing a predetermined light deflection on a surface of the substrate on which the inclined surface is formed.
[0028]
Therefore, by forming the electrode in the light transmitting region where the leaked light is generated, the electrode width can be narrowed, and an electric field distribution substantially parallel to the substrate surface can be uniformly generated. A reduction in the utilization efficiency is suppressed, and an optical deflection element with less alignment disturbance due to the uniformity of the electric field distribution.
[0029]
According to an eighth aspect of the present invention, in the light deflecting element according to any one of the first to seventh aspects, the electrode has a light-shielding property.
[0030]
Therefore, since the electrode also serves as a light-shielding member, it is possible to reliably shield only the deflecting light, which is leakage light, and to minimize a decrease in light use efficiency.
[0031]
According to a ninth aspect of the present invention, in the optical deflecting element according to any one of the first to eighth aspects, the inclined surface is a plurality of inclined surfaces that continuously appear in one direction. The concavities and convexities due to the continuation constitute a spacer that determines the distance between the two substrates.
[0032]
Therefore, since the unevenness due to the continuation of the inclined surface also serves as a spacer, the gap between the substrates can be minimized, and even when a liquid crystal cell is manufactured using a thin substrate, the deflection of the substrate can be suppressed and the gap of the liquid crystal cell can be made uniform. .
[0033]
According to a tenth aspect of the present invention, there is provided an image display device that spatially modulates illumination light based on image information and emits the image light as image light, and the image light is input from each pixel of the image display device in synchronization with the image display device. An optical deflecting element according to any one of claims 1 to 9, wherein the optical path of the incoming image light is deflected by the liquid crystal cell to increase the apparent number of pixels of the image display element for display. It is an image display device provided.
[0034]
Therefore, the same operation and effect as the invention described in any one of the first to ninth aspects can be obtained.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described.
[0036]
FIG. 1 is a conceptual diagram showing an overall configuration of an image display device 1 according to the present embodiment. As shown in FIG. 1, the light source 2 can use various illuminations for turning on / off white or arbitrary color light at high speed. For example, an LED lamp, a laser light source, a device in which a shutter is combined with a white lamp light source, or the like is used. The illumination device 3 is a device for uniformly irradiating the light emitted from the light source 2 to the image display element 4, and includes a diffusion plate 5, a condenser lens 6, and the like.
[0037]
The image display element 4 is a device that is driven by the display drive circuit 13 to display an image based on image data, and that spatially modulates incident uniform illumination light of the illumination device 3 and emits it as image light. A liquid crystal light valve, a reflection type liquid crystal light valve, a DMD element, or the like can be used.
[0038]
The light emitted from the light source 2 under the control of the light source drive circuit 7 becomes illumination light uniformed by the diffusion plate 5, and critically illuminates the image display element 4 by the condenser lens 6. Here, a transmissive liquid crystal light valve is used as an example of the image display element 4. The illumination light spatially modulated by the image display element 4 is enlarged by a projection lens 8 as image light and projected on a screen 9.
[0039]
The reduction optical element 10 reduces a display pixel of the image display element 4 and includes a micro lens, a collimator lens, and the like. It is desirable that the reduction amount is an integer fraction of the pixel pitch.
[0040]
Here, by controlling the applied voltage to the light deflecting element 11 disposed behind the image display element 4 and the reduction optical element 10 by the light deflecting voltage control circuit 12, the image light can be arbitrarily arranged in the pixel arrangement direction. Shifted by distance. The direction of the pixel shift is, as shown in FIG. 1, a vertical direction on the paper surface and a vertical direction on the paper surface. The light deflecting element 11 is arranged at the defocus position of the pixel displayed by the image display element 4 so as not to degrade the resolution of the displayed image. The shift amount of the pixel by the light deflecting element 11 is desirably 1 / integer of the pixel pitch, similarly to the reduction amount by the reduction optical element 10. When the shift amount is equal to the reduction amount, the shifted pixels do not overlap. . Therefore, the resolution does not decrease due to the effect of the pixel shift. If the shift amount is different from the reduction amount, the shifted pixels may be overlapped or the resolution may be reduced due to the spread between pixels. However, if the displayed image has no problem, the shift amount and the reduction amount may be reduced. The amounts need not be equal. When the image magnification is doubled in the pixel arrangement direction, the pixel pitch is set to 1/2, and when the pixel multiplication is tripled, the pixel pitch is set to 1/3. Further, when the shift amount becomes large due to the configuration of the optical path deflection voltage control circuit 12, the shift amount and the pixel reduction amount may be set to a distance of “integer multiple + one-integer” of the pixel pitch. In any case, the image display element 4 is driven by the image signal of the subfield corresponding to the pixel shift position, an apparent pixel multiplication effect is obtained as shown in FIG. 2, and the resolution of the used image display element 4 The above high-definition and high-contrast image can be displayed. In FIG. 2, the shift amount and the pixel pitch are indicated by arrows. Reference numeral 21 denotes one pixel displayed by the image display element 4, reference numeral 22 denotes one pixel incident on the light deflecting element 11, and reference numeral 23 denotes a pixel apparently multiplied by the light deflecting element 11.
[0041]
The image display control circuit 14 controls the light source drive circuit 7, the display drive circuit 13, and the light deflection voltage control circuit 12, and synchronizes the image display element 4 and the light deflection element 11.
[0042]
Next, details of the light deflecting element 11 will be described. FIG. 3 is a conceptual diagram illustrating a configuration example of a liquid crystal cell 31 used in the light deflecting element 11. As shown in FIG. 3A, the liquid crystal cell 31 includes a pair of transparent substrates 32, a liquid crystal layer 34 whose alignment state can be controlled by applying a voltage between the pair of substrates 32, and a light deflecting device. And a comb-shaped electrode 35 for applying an electric field to the liquid crystal layer 34 by the voltage control circuit 12. On the surface of at least one substrate 32 on the liquid crystal layer 34 side, a plurality of inclined surfaces 33 continuously appearing in one direction of the sawtooth shape are formed. The inclined surface 33 is inclined with respect to the opposite surface of the other substrate 32 in accordance with the direction of light deflection described later.
[0043]
Here, as shown in FIGS. 3A and 3B, the comb-shaped electrode 35 is a plurality of parallel line-shaped electrodes, and the polarity of the applied voltage is alternately different. And, the length direction is formed parallel to the sawtooth-shaped incision line of the continuous inclined surface 33 and is formed on the liquid crystal layer 34 side of the substrate 32. However, the present invention is not limited to this. It may be formed on the surface opposite to the liquid crystal layer 34, perpendicular to the engraved line of the shape.
[0044]
The shape and the number of arrays of the sawtooth of the inclined surface 33 shown in FIGS. 3A and 3C are not particularly limited, but are formed so as to have a predetermined deflection amount and a predetermined deflection direction. Since the alignment state of the liquid crystal of the liquid crystal layer 34 changes depending on the voltage application condition, by setting the voltage application condition, as shown in FIG. 4, the liquid crystal molecules 36 are in the first alignment state and the second alignment state. There can be two orientation states.
[0045]
Here, a change in the alignment state of the liquid crystal in the light deflection element 11 will be described with reference to FIG. The light deflecting element 11 of this example has a configuration similar to an optical deflecting element using a nematic liquid crystal that is homogeneously aligned with respect to the substrate plane. The alignment state of the liquid crystal changes depending on the voltage application condition, and the refractive index accordingly changes. Things that change. As described above, the comb-shaped electrode 35 is formed on the one substrate 32 of the pair, and the comb-shaped electrode 35 is applied with an electric field in the horizontal direction with respect to the liquid crystal director which is homogeneously aligned. It is configured as follows. Further, the inclined surface 33 is set in an inclined state so as to form an inclination ψ1 with respect to the normal direction of the incident light.
[0046]
As shown in FIG. 4B, which shows a cross-sectional view taken along the line AA 'in FIG. 4A, the liquid crystal director is oriented in two directions of a first orientation state and a second orientation state depending on the state of application of an electric field from the electrode. Is done. In the light deflecting element 11 having such a configuration, it is possible to efficiently deflect incident light by regulating the two alignment states of the liquid crystal in directions substantially orthogonal to each other as shown in FIG. 4B. . That is, when the incident light 41 is manipulated so that the linear polarization direction of the incident light 41 in FIG. 4 is in the Y-axis direction shown in FIG. 4 and is incident on the light deflecting element 11, the liquid crystal director faces the Z-axis direction. An electric field is applied by the comb-shaped electrode 35 as in the (first alignment state). In such a state, when the refractive index of the liquid crystal is equal to the refractive index of the substrate 32 sandwiching the liquid crystal, the incident light 41 behaves as ordinary light and passes through without being deflected. On the other hand, when no electric field is applied, a rubbing process is performed so that the liquid crystal director is oriented in a direction (Y-axis direction) perpendicular to the direction (the second alignment state). In such a state, when the refractive index of the liquid crystal is different from the refractive index of the substrate 32 sandwiching the liquid crystal, the incident light 41 is deflected by the difference in the refractive index from the interface which acts as extraordinary light.
[0047]
In order to regulate the liquid crystal in a direction in which the two alignment states are orthogonal to each other, a direction (Y) orthogonal to the direction of the applied electric field (Z-axis direction) is applied to an alignment film (not shown) formed on the surface of both substrates 32. The rubbing process is performed in the (axial direction), and the direction of the liquid crystal director is strongly restricted in a direction depending on the rubbing direction. For the alignment treatment, a normal alignment film such as polyimide used for TN liquid crystal and STN liquid crystal can be used. In addition, it is desirable to perform rubbing treatment or optical alignment treatment. If the direction can be controlled, the rubbing process and the optical alignment process may be omitted. The feature of the light deflecting element 11 having such a configuration is that the outgoing light with respect to the incident light 41 can be rotationally moved by the control of the liquid crystal director. Therefore, a desired amount of light deflection can be obtained by appropriately selecting the distance between the light deflection element 11 and the light receiving portion of the emitted light.
[0048]
Also, as shown in FIG. 5, by arranging such two liquid crystal cells 31 in the light traveling direction to constitute the light deflecting element 11, and appropriately selecting the distance X between the arranged liquid crystal cells 31, It is possible to obtain the necessary amount of light deflection while keeping the incident light and the outgoing light parallel. Accordingly, the amount of light deflection can be easily adjusted, and the light deflection element 11 having excellent convenience can be configured.
[0049]
Further, if the amount of light deflection is constant, an element configuration in which two liquid crystal cells 31 are provided in one light deflection element 11 via an intermediate substrate 42 having a thickness L as shown in FIG. Good. That is, a liquid crystal cell 31 configured to provide one intermediate substrate 42 instead of the substrate 32 facing the two liquid crystal cells 31 in the configuration of FIG. 5 is used.
[0050]
When determining the traveling direction of light in the configuration of the light deflecting element 11 as shown in FIG. 3, strictly speaking, a refractive index ellipsoid is obtained from both the direction of the liquid crystal director with respect to the traveling direction of the incident light 41 and the refractive indexes no and ne. The refractive index in each direction is determined based on the calculated light deflection direction, and the light deflection direction is determined based on the refractive index. However, here, it is assumed that the refractive index no and the refractive index ne are easily switched according to the alignment state of the liquid crystal, and assuming that Snell's law is followed as shown in FIG. May be called).
[0051]
That is, the refractive index in the major axis direction of the liquid crystal is ne, the refractive index in the minor axis direction is no, and the angle between the normal direction of the front interface of the liquid crystal and the light deflection direction with respect to the light traveling direction is ψ1 (≠ 0). ), The substrate 32 is arranged so that the angle formed by the normal to the rear interface and the incident light direction is 0 °. Further, an optical member in contact with the liquid crystal is selected to have a refractive index of no. According to Snell's law, the light deflection angle ψ2 at the front liquid crystal interface from the interface normal direction is
sinψ2 = (no / ne) sinψ1
More specifically, the light deflection angle 光線 3 of the light incident on the opposite substrate sandwiching the liquid crystal from the normal direction of the opposite substrate is:
ψ3 = ψ1-ψ2
More specifically, the light deflection angle の 4 of the light beam incident on the opposing substrate in the substrate is
sinψ4 = (ne / no) sinψ3
Find more.
[0052]
When the intermediate substrate 42 is provided and the parallel shift is performed as shown in FIG. 6, when the thickness of the intermediate substrate 42 is L, the thickness L required to obtain the shift amount x μm is as follows.
L · sinψ4 = x (μm)
Than,
L = x / sinψ4 (μm)
It becomes.
[0053]
In this manner, the light deflection direction changes mainly due to the inclination angle ψ1 of the inclined surface 33 of the substrate 32 and the refractive index anisotropy of the liquid crystal, and the amount of light deflection varies with the light emitted from the light deflection element 11. , The thickness of the liquid crystal layer 34, the thickness of the substrate 32, and the like. Here, the optical action of the optical deflecting element 11 can be performed by applying an electric field between the two substrates 32 instead of a lateral electric field and using a ferroelectric liquid crystal as a liquid crystal material. Poor yield in the manufacturing process.
[0054]
Thus, by using a lateral electric field drive and adopting a nematic liquid crystal as in the light deflecting element 11 of this example, the same optical action as that of the light deflecting element using the ferroelectric liquid crystal can be obtained, and the light having good alignment stability can be obtained. A deflection element can be manufactured.
[0055]
FIG. 5 or FIG. 6 is a specific configuration example when two liquid crystal cells 31 are used side by side.
[0056]
For example, when the configuration shown in FIG. 6 is used, as shown in FIG. 8, two liquid crystal cells 43 (liquid crystal cells 43a and 43b) are used, and the sawtooth cut lines 44a and 44b of the continuous inclined surface 33 are orthogonal. By arranging the two liquid crystal cells 43a and 43b in such a manner, the liquid crystal cell 43a can deflect in two directions in the Z direction, and the liquid crystal cell 43b can deflect in two directions in the Y direction. Become.
[0057]
Here, the two liquid crystal cells 43a and 43b are arranged so that the sawtooth-shaped engraving directions of the continuous inclined surface 33 are orthogonal to each other. However, the arrangement relationship is not limited to this. It suffices if four directions are possible. For example, only one of the liquid crystal cells 43a and 43b may be rotated by 45 ° on the ZY plane from the orthogonal arrangement state. The distance between the liquid crystal cells 43a and 43b is desirably set to a minimum, and the sawtooth shape of the continuous inclined surface 33 that can obtain a predetermined deflection direction instead of the two substrates 32 adjacent to the liquid crystal cells 43a and 43b. May be used on both surfaces.
[0058]
Here, even when the light is deflected in four directions, the light deflection operation principle is the same as the above-described two-direction deflection operation principle, and depends on the continuous inclination angle of the inclined surface 33 and the alignment state of the liquid crystal. The alignment state of the liquid crystal changes depending on the regulating force by the electric field and the regulating force by the rubbing treatment, and the deflection efficiency is better when the direction of the electric field is orthogonal to the rubbing direction. Therefore, when an electric field is applied so as to be orthogonal to the sawtooth-shaped notching direction of the continuous inclined surface 33, it is preferable that the rubbing be processed so as to be parallel to the sawtooth-shaped notching direction. Therefore, the liquid crystal cells 43a and 43b for driving the horizontal electric field are arranged as shown in FIG. 8, and the rubbing is processed so as to be parallel to the sawtooth-shaped notching direction of the continuous inclined surface 33. In this case, since the alignment state of the liquid crystal is always orthogonal to the optical axis, the direction of the electric field and the rubbing direction have a relationship as shown in FIG. 9, and two or more liquid crystal cells 43 under exactly the same conditions are used. By arranging, four-direction deflection can be realized.
[0059]
Here, even when the electric field is applied between the pair of substrates 32 instead of the lateral electric field driving to change the orientation of the liquid crystal and deflect light, two-way deflection is possible. Liquid crystal cells having different rubbing directions perpendicular to and parallel to the sawtooth-shaped cut lines of the continuous inclined surface 33 are required. This increases the number of manufacturing processes when manufacturing an optical deflection device, and increases the manufacturing yield and manufacturing cost.
[0060]
When two liquid crystal cells 43 having the same rubbing direction are used to deflect in four directions in the same manner as in the case of the horizontal electric field, a λ / 2 plate for rotating the polarization direction is required between the two liquid crystal cells 43. When manufacturing an optical deflection device using a λ / 2 plate, it is necessary to consider the wavelength dependence of the λ / 2 plate, and the transmittance of the entire device is reduced. Therefore, by using the lateral electric field driving for the liquid crystal cell 31 using the substrate 32 on which the continuous inclined surface 33 is formed, four-direction deflection can be performed regardless of the rubbing direction. Also, there is no need to use a λ / 2 plate.
[0061]
FIG. 19 shows a conceptual diagram of the arrangement of the liquid crystal cells 43 (43a, 43b) in the light deflection element 11. The light deflecting element 11 uses a plurality of, in this example, two, liquid crystal cells 43 arranged side by side. As for the continuous inclined surface 33 of the liquid crystal cell 43, one of the two liquid crystal cells 43 is formed in an array in the vertical direction on the paper surface and the other is formed in an array in the horizontal direction. When the light emitted from the image display element 4 is linearly polarized light in the vertical direction on the paper surface, the entire image display element 4 can be shifted in the horizontal and vertical directions on the paper surface in the order of pixels. As described above, by using two or more liquid crystal cells 43 using the horizontal electric field drive, it is possible to realize the image display device 1 with high definition and little reduction in contrast when shifting the screen in the vertical and horizontal directions.
[0062]
By the way, in the above-mentioned example, since the nematic liquid crystal is used as the liquid crystal material, there is a problem that the alignment stability is good but the response speed is slow.
[0063]
Therefore, the response speed can be improved by using a polymer stabilized liquid crystal formed by polymerizing and curing a monomer in a mixed system of a nematic liquid crystal and a polymerizable and curable monomer. This is characterized in that the nematic liquid crystal is configured to be reoriented by an electric field from the first state in which the nematic liquid crystal is maintained in a desired alignment state and to transition to a desired second state. Is desirably maintained in an orientation state where no electric field is applied when re-orientation is performed, for high-speed response.
[0064]
By adopting such a configuration, the response speed can be 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 during driving. This is because the contact area between the liquid crystal and the polymer is large, and 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 an electric field can be significantly increased. Furthermore, when photo-curing, the photo-curing is performed in a state where an electric field is applied in parallel with the substrate so that the long axis (when Δε is positive) or the short axis (when Δε is negative) of the liquid crystal is parallel to the substrate. Thus, the alignment regulating force is further increased, and a high-speed response can be performed. The monomer is excellent in light-curing type in terms of ease of forming an element and a wide range of material selection, and has a high degree of freedom in curing conditions, and is suitable for high-speed design compared to thermosetting type. It is preferable that the formed polymer has a liquid crystal skeleton as a partial structure in order to increase the change in the refractive index and prevent clouding. Further, the concentration of the polymerizable and curable monomer in the liquid crystal material is desirably 15% by weight or more.
[0065]
Further, the response speed is increased by using a material in which dielectric anisotropy changes to positive or negative in accordance with the frequency of the applied voltage, that is, a so-called two-frequency driving liquid crystal, as another liquid crystal material. For example, when a voltage having a positive dielectric anisotropy is applied to the liquid crystal, the major axis of the liquid crystal molecules is oriented in the direction of the electric field, and when a voltage having a negative dielectric anisotropy is applied to the liquid crystal, the direction of the electric field is changed. The short axis of the liquid crystal molecule is oriented. By using a material having such properties, the alignment state of the liquid crystal changes depending on two frequencies. As the liquid crystal material, any of cyano-based, fluorine-based, and chlorine-based liquid crystals can be used as long as they have such characteristics. The frequency of the input signal may be set to either the beginning. This is because the alignment state of the liquid crystal is changed by the electric regulation force, so that the response speed is increased. When such driving is performed, the alignment of liquid crystal molecules hardly contributes to rubbing. Therefore, a rubbing treatment and an initial alignment electrode are not required, and the effect of simplifying element fabrication can be expected.
[0066]
FIG. 10A shows an electric field distribution when the initial alignment (rubbing treatment) of the liquid crystal is set to be parallel to the sawtooth line direction of the electrode 35 and a voltage is applied to the electrode 35. The voltage is set so that the adjacent electrodes 35 are alternately turned on and off so that an electric field E is applied between the comb-shaped electrodes 35. Since the liquid crystal director faces the direction of the electric field E, the electrodes 35 Between them, they face in the direction perpendicular to the direction of the sawtooth line. However, in the vicinity of the electrode 35, such an electric field E is not applied and the alignment state of the liquid crystal does not change. That is, as shown in FIG. 10C with respect to FIG. 10B, even when the light is deflected, the light passing through the electrode 35 is not deflected and becomes leaked light.
[0067]
Therefore, as shown in FIG. 11, when viewed from the substrate surface of the substrate 32 on the light emission side, the light-shielding member 51 is located at a position that overlaps each electrode 35, that is, a position that shields the optical axis overlapping the electrode 35 and shields leaked light. Is provided. In FIG. 11, the light shielding member 51 is provided on the substrate 32 on the light emitting side. However, the present invention is not limited to this. On the optical axis of the leaked light indicated by the phantom arrow in FIG. (A position overlapping with each electrode 35 when viewed from the substrate surface).
[0068]
Here, when the position where the light shielding member 51 is provided is the light emitting side substrate 32 as shown in FIG. 11, the light shielding member 51 can be provided even after the liquid crystal cell 31 is manufactured, and the light shielding member 51 can be accurately positioned. Can be formed. In addition, simple processing steps such as printing can be performed. Further, the light shielding member 51 is desirably large from the viewpoint of shielding the leaked light. However, if it is too large, the light shielding member 51 blocks necessary light, and the overall light amount is reduced. On the other hand, if the light shielding member 51 is small, the overall light amount increases, but the ability to shield the leaked light is reduced, and the contrast is reduced. Therefore, it is necessary to appropriately set the size of the light shielding member 51 according to whether the overall light amount and contrast are good or bad, the position of the light shielding member 51, and the like.
[0069]
The material of the light shielding member 51 is selected so as to prevent transmission of light, and for example, a metal such as Al or Cr, an acrylic resin added with carbon, an organic material such as a resist material, or carbon alone can be used. . Further, the formation of the light shielding member 51 can be performed by photolithography, sputtering, or the like using a light shielding pattern mask corresponding to leakage light.
[0070]
As a method of forming the continuous inclined surface 33 having a sawtooth shape, there is a method of etching a glass substrate or processing a transparent plastic material by injection molding or the like. (A typical sawtooth shape is a right triangle), and it is difficult to form minute inclined surfaces 33 in an array. When the glass substrate is formed by etching, the formed saw-tooth shape is such that the saw-tooth edge is curved or the size of the two inclination angles forming the saw-tooth is close (the saw-tooth shape is close to an isosceles triangle). ), And such a sawtooth shape results in a plurality of light deflection directions. In addition, a portion corresponding to the edge of the sawtooth has a disadvantage that the liquid crystal alignment is likely to be disordered.
[0071]
FIG. 12 shows a deflection operation of the liquid crystal cell 31 using the substrate 32 in which the inclination angles of the two inclined surfaces 33 forming the sawtooth are close to each other. As described above, depending on the orientation of the liquid crystal molecules 36, the incident light goes straight or is deflected. Since the alignment state of the liquid crystal molecules 36 in FIG. 12A is oriented so that the refractive index is no with respect to the polarization direction of the incident light, the incident light proceeds straight without being deflected. In addition, since the orientation state of the liquid crystal molecules 36 in FIG. 12B is oriented so as to have a refractive index ne with respect to the polarization direction of the incident light, the incident light is deflected. Since the light deflecting direction is caused by the inclination of the inclined surface 33, if the inclined surface has two gentle inclined angles in the sawtooth shape (the inclination angle of the two inclined surfaces 33 and 52 forming the sawtooth is large). In the case where there is no difference), as shown in FIG. 12B, the deflection direction becomes two directions in one orientation state of the liquid crystal molecules 36, and one direction becomes light leakage.
[0072]
When the liquid crystal cell 31 exerts a deflecting action as described above, if the deflecting direction is one direction or more, as shown in FIG. 13, the comb is parallel to the sawtooth-shaped inscribed lines of the inclined surfaces 33 and 52. A tooth-like electrode 35 is formed. Here, since the light-blocking member 51 is provided at a position overlapping the electrode 35 on the optical axis, light that is leaked light due to the saw-toothed unevenness is blocked, and the light is emitted when the liquid crystal molecules 36 are in one alignment state. On the side, the deflection direction becomes one direction, and the incident light can be uniformly deflected. In this case, the number of lines of the comb-shaped electrode 35 is the same as the number of sawtooth arrays (the number of continuous inclined surfaces 33) formed by the inclined surfaces 33 and 52, and corresponds to the leakage light position caused by the sawtooth shape. Then, it is desirable to form the comb-shaped electrode 35.
[0073]
Further, as shown in FIG. 14, with respect to the sawtooth shape formed by the inclined surfaces 33 and 52, there is a problem that the liquid crystal alignment is disturbed due to the apex portion 53 of the sawtooth shape and the inclined surface 52. Therefore, by forming the comb-shaped electrode 35 at a position including the normal line 55 passing through the center of the sawtooth-shaped step portion 54 (the portion of the inclined surface 52), the liquid crystal layer 34 is disordered in liquid crystal alignment, that is, The leakage light component caused by the disturbance of the liquid crystal alignment of the liquid crystal layer 34 in the step portion 54 in the region between the portion 53 and the inclined surface 33 can be shielded. Here, since the oblique component of the incident light changes depending on the design of the optical system, the width of the comb-shaped electrode 35 is not particularly limited. However, it is possible to set the optimum width from two viewpoints, that is, leaked light and liquid crystal misalignment. desirable.
[0074]
Further, as shown in FIG. 15, when the comb-shaped electrode 35 is formed on the inclined surface 52 of the substrate 32 that generates the leaked light, the electrode width becomes small when viewed from the light emitting surface, and the electric field distribution becomes substantially uniform. Therefore, the liquid crystal molecules 36 on the electrodes 35 are also changed in the direction of the electric field. Therefore, no light leaks from the electrode 35, and the light use efficiency is improved. As a method of forming the electrode 35, a linear opening pattern is formed on the inclined surface 52 by using a photoresist, and then the electrode 35 can be formed by sputtering.
[0075]
When the deflection direction is two directions, the light shielding member 51 is provided on the substrate 32 having the continuous inclined surfaces 33 and 52 sandwiching the liquid crystal layer 34 and the substrate 32 facing the substrate 32. Then, the polarized light which does not become the leak light is also partially shielded. Further, since the deflected light is scattered by the sawtooth-shaped surface roughness due to the inclined surfaces 33 and 52, the apex 53, and the like, the area of the light shielding member 51 needs to be slightly increased. However, by providing the light-blocking member 51 on the light-incident side substrate 32, light before leaking light (light before deflection) can be shielded, and therefore there is almost no influence of scattering by the inclined surfaces 33 and 52. Therefore, the light shielding member 51 requires only a relatively small area, so that a decrease in light use efficiency can be suppressed.
[0076]
Further, as shown in FIG. 16, when the light shielding member 51 is provided on the inclined surface 52 of the substrate 32 on the light incident side where the leakage light is generated, or when the material of the electrode 35 is made of a light shielding material such as Al or Cr. Can reliably block only the deflected light that is leaked light, so that a decrease in light use efficiency can be minimized.
[0077]
Here, a structure for preventing light from being incident on a region other than the inclined surfaces 33 and 52 that cause predetermined light deflection on the substrate 32 on the light incident side may be provided on the light incident side of the liquid crystal cell 31 or may be a leakage light. It is effective in suppressing
[0078]
As one example of this, it is effective to provide a condensing element on the light incident side of the liquid crystal cell 31, and the incident light can be collected on the inclined surfaces 33 and 52. In this case, it is desirable to set the light incident angles on the inclined surfaces 33 and 52 to be small enough that no problem occurs in the predetermined deflection angle. For example, when a microlens array is used as a light condensing element, the light incident angle can be reduced by setting the F value of the microlens large.
[0079]
As another example, as shown in FIG. 17, a condensing and parallel optical lens array 61 such as a micro lens and a collimating lens may be provided on the light incident side. In this case as well, light that becomes leakage light is condensed and light that is affected by absorption and reflection by the light shielding member 51 is reduced, so that light utilization efficiency can be improved. The installation of the converging and collimating optical lens array 61 minimizes the light that is leaking. For example, the pitch of the lens array is determined so that the light is condensed and transmitted through the parallel optical lens array 61 and converges on the opening 62.
[0080]
In the configuration of the liquid crystal cell 31 shown in FIG. 18, the two substrates 32 and 32 facing each other are in contact with each other, and the gap of the liquid crystal layer 34 is set to the height of the irregularities of the sawtooth-shaped portion formed by the continuous inclined surfaces 33 and 52. Is done. Since the saw-tooth shape is an array, the gap of the liquid crystal cell 31 can be made uniform, and the minimum gap can be secured because no spacer is used. That is, the unevenness of the sawtooth-shaped portion formed by the inclined surfaces 33 and 52 functions as a spacer that determines the interval between the substrates 32.
[0081]
FIG. 1 shows an example of a color image display device 1 using an image display element 4 which is a transmission type liquid crystal light valve combined with a color filter and a light source 2 of a white lamp. A full-color image can also be displayed by a field sequential method in which the single-plate image display element 4 is sequentially illuminated with three primary colors of light. In this case, time-sequential three primary color lights may be generated by combining a light source of a white lamp and a rotating color filter.
[0082]
【Example】
An embodiment of the present invention will be described.
[0083]
[Example 1]
A quartz glass substrate (manufactured by Shin-Etsu Chemical Co., Ltd.) having a size of 3 cm × 4 cm and a thickness of 1 mm is prepared as a pair of substrates 32, and a mask pattern (pitch: 110 μm, line: 24 μm) having comb-shaped openings is used for one of them. An ITO (film thickness: 1400 °) electrode having a comb-tooth pattern was formed on one surface of the substrate 32 as an electrode. On one surface of the other substrate 32, a sawtooth array was machined to form continuous inclined surfaces 33, 52. The saw-tooth array was processed on the substrate 32 by using a grating mask (manufactured by Dai Nippon Printing) by photoresist and dry etching. FIG. 20 shows the processed sawtooth shape. The resist material (manufactured by Tokyo Ohka Co., Ltd.) was formed with a thickness of 2 μm by a spin coater, and the photoresist was exposed by arranging a diffusion plate on a mask and optimizing the conditions of alignment and exposure. The mask has a pattern in which the line width is changed from 0.5 to 4 μm (0.5 μm interval) at a pitch of 4 μm, and one pattern corresponds to one saw-tooth shape (pitch 110 μm). As the initial alignment treatment, a polyimide alignment material (using AL3046-R31 manufactured by JSR) was spin-coated on the ITO side and the sawtooth side of the substrate 32 to form an alignment film of about 0.3 μm. After the annealing of the substrate 32, the rubbing of the substrate 32 on which the saw-tooth shape is formed is performed by performing a rubbing process in a direction parallel to the saw-tooth-shaped engraved line, and the rubbing of the substrate 32 on which the comb-shaped electrode 35 is formed. Rubbed in the direction parallel to the comb teeth. After laminating and pressing the sawtooth-shaped substrate 32 and the substrate of the comb-tooth electrode 35 so that the rubbing directions of both substrates 32 become parallel, UV irradiation was performed to produce an empty cell of the liquid crystal cell 31. The gap was adjusted at a ratio of 1: 100 with a mixture of 4 μm braided balls and a UV-curable adhesive (using 3052 made by ThreeBond). Care was taken not to form a saw-tooth shape between the two glass substrates 32, 32. Was applied. After the production of the empty cell, a nematic liquid crystal material (using ZLI-2471 manufactured by Merck) was injected by a capillary method to produce a liquid crystal cell 31 (the cell thus produced is referred to as Sample 1). Since the rubbing directions of the upper and lower substrates 32 and 32 match, the liquid crystal molecules are parallel to the substrates and are all aligned in the same direction (homogeneous alignment).
[0084]
The sample 1 thus manufactured is driven by applying a voltage. As a driving method, a lateral electric field drive was performed so that an electric field was applied between the comb-shaped electrodes 35, and a voltage of 10 V was applied using a function generator. The input waveform was a rectangular wave, and the voltage value was checked with a tester. Laser light (633 nm) having a diameter of 1 mm was used as light incident on the liquid crystal cell 31, the incident light was converted into linearly polarized light by a polarizing plate, and was incident on the sawtooth array position of the liquid crystal cell 31. The polarization direction of the incident light was set so as to be parallel to the sawtooth-shaped inscribed line. The liquid crystal cell 31 was operated, and the transmitted light passing through the liquid crystal cell 31 was observed by a CCD camera. As a result, it was confirmed that the transmitted light was deflected by the voltage.
[0085]
The liquid crystal material was ferroelectric liquid crystal (CS-1029 manufactured by Chisso Corporation), and a liquid crystal cell 31 was manufactured by the same manufacturing method as described above. However, the liquid crystal was injected on a hot plate (90 ° C.) and allowed to cool after the injection. As a result of observing the orientation of the liquid crystal cell 31 of the manufactured ferroelectric liquid crystal and the sample 1 with a microscope, the orientation of the sample 1 using the nematic liquid crystal was more uniform.
[0086]
In addition, two liquid crystal cells 31 of Sample 1 manufactured by the above-described method were prepared, and the two liquid crystal cells 31 were arranged so that the saw-tooth-shaped engraved lines were orthogonal to each other. When each of the liquid crystal cells 31 was driven in the lateral electric field in the same manner as described above, deflection in four directions was obtained by changing the voltage application conditions.
[0087]
Here, in order to perform deflection in four directions in a driving method in which an electric field is applied between the substrates 32, 32 without using the lateral electric field driving, the liquid crystal alignment processing (rubbing processing) is performed in parallel with the sawtooth-shaped notching line. Liquid crystal cells having different production conditions in the orthogonal direction had to be prepared. Further, in the case where the rubbing process uses liquid crystal cells in the same direction, a λ / 2 plate must be used between the liquid crystal cells. An inexpensive four-direction deflectable optical deflection element was manufactured.
[0088]
[Example 2]
In the manufacturing method of the liquid crystal cell 31 of Example 1, the liquid crystal is a material obtained by mixing a prepolymer of a photocurable polymer having a liquid crystal skeleton as a partial structure with a nematic liquid crystal (using ZLI-2471 manufactured by Merck) by a capillary method. A liquid crystal cell 31 was prepared by injecting into the cell and mixing 1 wt% of a photopolymerization initiator (using IRG-651 from Ciba-Geigy) with the polymerizable liquid crystal. The prepolymer is 20 mW / cm ² Irradiation was performed for 1 minute at room temperature in the absence of an electric field to form a polymer, and the concentration of the prepolymer was adjusted to 0 to 20%.
[0089]
The response speed of the liquid crystal cell 31 is such that a comb-shaped electrode 35 is irradiated with a laser beam having a wavelength of 633 nm, the light deflected by the birefringence of the liquid crystal is condensed by a lens, and a part of the light is received by a photodiode. Then, the speed was determined by converting it into a voltage change and observing it with an oscilloscope. Since the intensity of the deflecting light is reduced by the switching of the applied voltage, the speed at which the light intensity recovers again from 100% and changes to 90% is defined as the response speed. As a result, the response speed is not different from the case of 0% up to the prepolymer concentration of 5%, but shows a response speed on the order of μsec at 10% or more, and the response speed is less than 500 μsec at 15%, and can sufficiently endure moving image display. was gotten.
[0090]
[Example 3]
A black ink as a light shielding member 51 was printed at a line width of 24 μm at a position corresponding to the electrode 35 on the opposite surface of the liquid crystal cell 31 formed in the same manner as in Example 1 where the electrode 35 was formed. The light shielding member 51 was printed at a position where light leaked due to the inclined surface 52 was shielded. Such a liquid crystal cell 31 is referred to as a sample 2.
[0091]
A voltage is applied to the manufactured liquid crystal cell 31 to drive it. As a driving method, a lateral electric field drive was performed so that an electric field was applied between the comb-shaped electrodes 35, and a voltage of 10 V was applied using a function generator. The input waveform was a rectangular wave, and the voltage value was checked with a tester. The incident light on the liquid crystal cell 31 was a laser beam (633 nm) having a diameter of 1 mm, and the incident light was converted into linearly polarized light by a polarizing plate, and was incident on the sawtooth array position of the liquid crystal cell 31. The polarization direction of the incident light was set so as to be parallel to the sawtooth-shaped inscribed line. The liquid crystal cell 31 was operated, and the transmitted light passing through the liquid crystal cell 31 was observed by a CCD camera. As a result, it was confirmed that the transmitted light was deflected by the voltage.
[0092]
However, the transmitted light after deflection was split into two in sample 1 and not split in sample 2. Therefore, it can be seen that the direction of the deflected light can be made uniform by providing the light shielding member 51 corresponding to the leaked light. FIG. 21 shows the observation results of Sample 1 and Sample 2. FIG. 21A shows Sample 1 and FIG. 21B shows Sample 2. In the sample 1 of FIG. 21A, the number of observation images of the deflection 1 is two, and the number of deflection directions is two. On the other hand, in the sample 2 of FIG. The number was one and the number of deflection directions was one.
[0093]
[Example 4]
In the method of manufacturing the liquid crystal cell 31 of Example 1, the electrode 35 made of Cr was formed corresponding to the inclined surface 52 of the saw-toothed substrate 32. As a forming method, a mask pattern having a stripe-shaped opening having a pitch of 110 μm and a width of 24 μm was used. The liquid crystal cell 31 in which the electrode 35 (light shielding member 51) of the light shielding material is provided on the inclined surface 52 in this manner is referred to as a sample 3. In Samples 2 and 3, the transmitted light of the liquid crystal cell 31 was obtained when the light-shielding member 51 was installed on the substrate 32 on the light-emitting side and when the light-shielding member 51 was installed on the substrate 32 on the light-incident side of the sawtooth shape. The results of comparing the light energy of the two are as follows. That is, the energy (relative value) of the transmitted light of the former was 12.3%, and the energy (relative value) of the transmitted light of the latter was 16%. As described above, when the light shielding member 51 was provided on the substrate 32 on the light incident side of the sawtooth shape, the light amount was 3.7% larger. Therefore, the light use efficiency is better when the light shielding member 51 is provided on the substrate 32 on the light incident side of the sawtooth shape.
[0094]
[Example 5]
In the method of manufacturing the liquid crystal cell 31 of the first embodiment, the substrates 32 and 32 are bonded only with the UV curing adhesive without using a true thread ball serving as a gap at the time of bonding. did. This liquid crystal cell 31 is referred to as sample 4. The cell gap between Sample 1 and Sample 4 was measured by a microscopic polarization spectrophotometer (manufactured by Oak Co., Ltd.) at 5 points in a 1 mm × 1 mm area around the sawtooth shape at equal intervals in the vertical and horizontal directions. In this case, the variation in the cell gap (sample 3) using a true yarn ball as the spacer was ± 2 μm, and the variation in the cell gap (sample 4) when the saw tooth shape was used as the spacer without using the true yarn ball was ± 1 μm. . From this, the gap can be made more uniform in the liquid crystal cell 31 using the sawtooth shape as the spacer.
[0095]
[Example 6]
An image display device 1 as shown in FIG. 1 was manufactured. As the image display element 4, a 0.9 inch diagonal XGA (1024 × 768 dots) polysilicon TFT liquid crystal cell was used. The pixel pitch is about 18 μm both vertically and horizontally. The aperture ratio of the pixel is about 50%. Further, the illumination device 3 is provided on the light source 2 side of the image display element 4 to increase the light collection rate of the illumination light. As a light source 2, a white lamp was used, and color display was performed by an image display element 4 which is a transmission type liquid crystal light valve provided with a color filter on each pixel surface. In addition, the reduction optical element 10 was configured using a micro lens and a collimating lens, and was installed immediately after the image display element 4 to adjust the alignment with the pixel position.
[0096]
Then, two samples 1 manufactured in Example 1 were used, and the structure as shown in FIG. 5 was used as sample 5, and the width between the substrates 32 of sample 5 was adjusted so that the shift amount was 9 μm. . Further, a sample 6 having the same configuration as that of the sample 5 was prepared, and the serrated line of the sample 5 and the serrated line of the sample 6 were arranged so as to be orthogonal to each other. A diffusion plate having a thin diffusion layer is aligned with the exit side of the liquid crystal cell 31, and the diffused light on the exit surface is enlarged. As a result of observing a display image, the pixel density in the vertical and horizontal directions is twice as high, and the contrast is good. An image was obtained.
[0097]
【The invention's effect】
According to the first aspect of the present invention, the alignment stability is good, and the same optical action as that of the light deflecting element using the ferroelectric liquid crystal can be obtained. Further, in the case where a plurality of liquid crystal cells are arranged and the light deflecting element is configured so that the deflecting direction of the emitted light becomes four directions, a liquid crystal is driven in a lateral electric field to form a substrate having an inclined surface in the light deflecting element. The rubbing direction to the substrate may always be the same as the shape of the inclined surface, and light can be deflected in four directions without a λ / 2 plate between the light deflecting elements. Can be made relatively simple and at low manufacturing cost.
[0098]
According to a second aspect of the present invention, in the first aspect, a high response speed of the liquid crystal can be obtained.
[0099]
According to a third aspect of the present invention, in the first aspect of the present invention, the electrode configuration is simple because there is no need for a separate electrode for electrically returning to the initial alignment state, and the initial alignment state is returned with a weak rubbing control force. A faster response speed can be obtained.
[0100]
According to a fourth aspect of the present invention, in the first aspect of the present invention, an optical deflecting element having a uniform deflection direction can be configured.
[0101]
According to a fifth aspect of the present invention, in the invention of the fourth aspect, leak light caused by the electrodes and leak light caused by the inclined surface shape can be shielded, and leak light that is not deflected is shielded, so that a uniform deflection direction is obtained. Is obtained.
[0102]
According to a sixth aspect of the present invention, in the fourth aspect of the invention, a light deflecting element having a uniform deflecting direction is provided, which absorbs light leaked by the liquid crystal alone and blocks all non-deflected light.
[0103]
The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the electrode width can be formed narrow, and an electric field distribution substantially parallel to the substrate surface can be uniformly generated. In addition, since the electrode width is narrow, a reduction in light use efficiency is suppressed, and the uniformity of the electric field distribution results in a light deflection element with little alignment disturbance.
[0104]
According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, it is possible to reliably block only the deflecting light that becomes leakage light, and to minimize the decrease in light use efficiency. it can.
[0105]
According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the gap between the substrates can be minimized, and even when a liquid crystal cell is manufactured using a thin substrate, the deflection of the substrate can be achieved. And the gap of the liquid crystal cell can be made uniform.
[0106]
The invention according to claim 10 has the same effect as the invention according to any one of claims 1 to 9.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an image display device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating pixel shift by a light deflecting element of an image display device.
FIG. 3 is an explanatory diagram illustrating a configuration of a light deflecting element.
FIG. 4 is an explanatory diagram illustrating the orientation of liquid crystal of the light deflecting element.
FIG. 5 is an explanatory diagram illustrating a configuration example when two liquid crystal cells are used.
FIG. 6 is an explanatory diagram illustrating another configuration example when two liquid crystal cells are used.
FIG. 7 is an explanatory diagram illustrating Snell's law.
FIG. 8 is an explanatory diagram illustrating a configuration example of a light deflection element that performs light deflection in four directions.
FIG. 9 is an explanatory diagram illustrating the light deflecting element of FIG. 8;
FIG. 10 is an explanatory diagram illustrating an operation of the light deflecting element.
FIG. 11 is an explanatory diagram of a light deflecting element provided with a light shielding member.
FIG. 12 is an explanatory diagram of light leakage in a light deflection element.
FIG. 13 is an explanatory diagram of a configuration example in which unevenness of a substrate and an electrode in an optical deflection element are configured to be parallel to each other, and leakage light is blocked by a light blocking member.
FIG. 14 is an explanatory diagram of a configuration example in which light leaking due to a top portion and a step portion of the unevenness of the substrate in the light deflection element is shielded.
FIG. 15 is an explanatory diagram of a configuration example in which an electrode is provided on a step portion of the unevenness of the substrate in the light deflection element.
FIG. 16 is an explanatory diagram of a configuration example in which a light-shielding electrode is provided in a step portion of the unevenness of the substrate in the light deflection element.
FIG. 17 is an explanatory diagram of a configuration example of a light deflecting element provided with a condensing and parallel optical lens array.
FIG. 18 is an explanatory diagram of a configuration example of an optical deflecting element using unevenness of a substrate in the optical deflecting element as a spacer.
19 is an explanatory diagram of an arrangement of each element in the configuration of FIG.
FIG. 20 is an explanatory diagram of the first embodiment.
FIG. 21 is an explanatory diagram of a third embodiment.
[Explanation of symbols]
1 Image display device
4 Image display device
11 Optical deflection element
31 liquid crystal cell
32 substrates
33 slope
34 liquid crystal layer
35 electrodes
43 liquid crystal cell
51 Light shielding member

Claims (10)

One or a plurality of liquid crystal cells arranged side by side to deflect and emit incident light,
Each of the liquid crystal cells,
A pair of transparent substrates,
A liquid crystal layer containing a nematic liquid crystal filled between the substrates,
An electrode for applying an electric field in the direction of the plate surface of the substrate to the liquid crystal layer to deflect an optical path of light transmitted through the liquid crystal layer;
An inclined surface formed on a surface of the at least one substrate on the liquid crystal layer side and inclined with respect to a facing surface of the other substrate in accordance with the direction of the deflection,
Has,
Light deflection element. The nematic liquid crystal is a polymer stabilized liquid crystal,
The light deflection element according to claim 1. The liquid crystal material of the nematic liquid crystal is a material whose dielectric anisotropy changes to positive or negative in accordance with the applied voltage frequency,
The light deflection element according to claim 1. A light-shielding member that shields an optical axis overlapping the electrode,
The light deflecting element according to claim 1. The inclined surface is a plurality of inclined surfaces continuously appearing in one direction,
The electrode is a plurality of parallel linear electrodes having different applied voltage polarities alternately, and the length direction is parallel to the direction of the indentation line of the unevenness due to the continuation of the inclined surface, and leakage caused by the unevenness is caused. Formed at the light position,
The light deflecting element according to claim 4. The inclined surface is a plurality of inclined surfaces continuously appearing in one direction,
The light-shielding member shields leakage light generated from disturbance of liquid crystal alignment of the liquid crystal layer in a vertex portion of unevenness due to continuation of the inclined surface and a region between the inclined surfaces,
The light deflecting element according to claim 4. The inclined surface is a plurality of inclined surfaces continuously appearing in one direction,
The electrodes are a plurality of parallel linear electrodes having alternately applied voltages having different polarities, and are formed in a light transmitting region other than causing a predetermined light deflection on a surface of the substrate on which the inclined surface is formed. ing,
The light deflecting element according to claim 1. The electrode has a light-shielding property,
The light deflecting element according to claim 1. The inclined surface is a plurality of inclined surfaces continuously appearing in one direction, the unevenness due to the continuation of the inclined surface constitutes a spacer that determines the distance between the two substrates,
An optical deflecting element according to claim 1. An image display element that spatially modulates illumination light based on image information and emits the image light as image light,
In synchronism with the image display device, the optical path of image light incident from each pixel of the image display device is deflected by the liquid crystal cell to increase the apparent number of pixels of the image display device for display. An optical deflecting element according to any one of Items 1 to 9,
An image display device comprising:

Images