JP4773649B2 - Optical deflection apparatus and image display apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an optical deflection device that changes the direction of light according to an electric signal, and the optical deflection device.TheThe used image display device is suitable for application to an electronic display device such as a projection display or a head mounted display.
[0002]
First, terms used in this specification will be defined.
In this specification, “light deflecting element” refers to whether the optical path of light is deflected by an external electric signal, that is, the outgoing light is shifted in parallel to the incident light, or is rotated at a certain angle. Alternatively, it means an optical element capable of switching the optical path by combining both of them. In this description, the magnitude of the shift is referred to as “shift amount” with respect to the light deflection due to the parallel shift, and the rotation amount is referred to as “rotation angle” with respect to the light deflection due to rotation. The “light deflection device” means a device that includes such a light deflection element and deflects the optical path of light.
[0003]
The “pixel shift element” is an image display element in which a plurality of pixels that can control light according to image information is two-dimensionally arranged, a light source that illuminates the image display element, and an image displayed on the image display element. An optical member for observing the pattern, and a light deflecting means for deflecting the optical path between the image display element and the optical member for each of a plurality of subfields obtained by dividing the image field in time. Means light deflecting means in an image display device that displays an image pattern in which the display position is shifted according to the deflection of the optical path for each field, thereby increasing the apparent number of pixels of the image display element. To do. Therefore, basically, it can be said that the optical deflection element and the optical deflection device defined above can be applied as the optical deflection means.
[0004]
[Prior art]
Conventionally, KH has been used as an optical element as a light deflection element.₂PO_Four(KDP), NH_FourH₂PO_Four(ADP), LiNbO_Three, LiTaO_Three, GaAs, CdTe, and other materials having a large primary electro-optic effect (Pockels effect), KTN, SrTiO_Three, CS₂, Electro-optic devices using materials with large secondary electro-optic effect such as nitrobenzene, glass, silica, TeO₂Acoustooptic devices using materials such as these are known (for example, Shoji Aoki; “Optoelectronic Device”, Shosodo). In general, in order to obtain a sufficiently large amount of light deflection, it is necessary to take a long optical path length, and the use is limited because the material is expensive.
[0005]
On the other hand, various types of optical elements, which are light deflecting elements using a liquid crystal material, have been proposed, and several examples thereof are as follows.
For example, according to Japanese Patent Laid-Open No. 6-18940, a light beam shifter made of an artificial birefringent plate is proposed for the purpose of reducing the light loss of the optical space switch. In detail, a light beam shifter in which two wedge-shaped transparent substrates are arranged in opposite directions, a liquid crystal layer is sandwiched between the transparent substrates, and the light beam shifter is connected to the rear surface of a matrix type deflection control element. A beam shifter has been proposed. At the same time, two wedge-shaped transparent substrates are arranged in opposite directions, matrix drive is possible between the transparent substrates, and a light beam shifter sandwiching a liquid crystal layer that shifts the incident light beam by half a cell There has been proposed a light beam shifter in which multiple stages are shifted by half a cell.
[0006]
Japanese Patent Laid-Open No. 9-133904 proposes an optical deflection switch that can obtain a large deflection, has a high deflection efficiency, and can arbitrarily set a deflection angle and a deflection distance. Yes. Specifically, two transparent substrates are arranged opposite to each other at a predetermined interval, a vertical alignment process is performed on the opposed surfaces, and a smectic A phase ferroelectric liquid crystal is sealed between the transparent substrates. The liquid crystal element includes a driving device that is vertically aligned with respect to the electrode pair, the electrode pair is arranged so that an AC electric field can be applied in parallel with the smectic layer, and the AC electric field is applied to the electrode pair. In other words, the refraction angle and the direction of displacement of the polarized light incident on the liquid crystal layer can be changed by the birefringence due to the inclination of the liquid crystal molecules by using the electroclinic effect of the smectic A phase ferroelectric liquid crystal.
[0007]
In the above-mentioned Japanese Patent Application Laid-Open No. 6-18940, nematic liquid crystal is used as the liquid crystal material, so it is difficult to increase the response speed to sub-milliseconds and cannot be used for applications that require high-speed switching. .
In the above-mentioned Japanese Patent Application Laid-Open No. 9-133904, a smectic A-phase ferroelectric liquid crystal is used. However, since the smectic A-phase does not have spontaneous polarization, high-speed operation cannot be expected.
[0008]
Next, several techniques that have been conventionally proposed for the pixel shift element will be described.
For example, as shown in Japanese Patent No. 2939826, in a projection display apparatus that enlarges and projects an image displayed on a display element onto a screen by a projection optical system, transmitted light is transmitted in the middle of an optical path from the display element to the screen. Means for shifting a projection image having at least one optical element capable of turning in the deflection direction and at least one transparent element having a birefringence effect, and effectively reducing the aperture ratio of the display element And a projection display device provided with means for discretely projecting the projection area of each pixel of the display element on the screen.
[0009]
In Japanese Patent No. 2939826, at least one optical element (referred to as an optical rotatory element) capable of rotating the deflection direction and at least one transparent element (referred to as a birefringent element) having a birefringence effect are included. The pixel shift is performed by the projection image shift means (pixel shift means) as described above. However, since the optical rotation element and the birefringence element are used in combination, there is a large loss of light amount, and the pixel shift amount depends on the light wavelength. The resolution tends to decrease and optical noise such as ghost due to leaked light is likely to occur at positions outside the pixel shift where the image is not originally formed due to mismatch in optical characteristics between the optical rotator and the birefringent element, and elementization It is mentioned that the cost for is large. In particular, the KH as described above for the birefringent element₂PO_Four(KDP), NH_FourH₂PO_Four(ADP), LiNbO_Three, LiTaO_ThreeThis is remarkable when a material having a large primary electro-optic effect (Pockels effect) such as, GaAs, CdTe is used.
[0010]
In the projector disclosed in Japanese Patent Application Laid-Open No. 5-313116, the image to be originally displayed stored in the image storage circuit is sampled in a checkered pattern in the pixel selection circuit by the control circuit and sequentially displayed on the spatial light modulator. Then, the control circuit controls the panel rocking mechanism in correspondence with the display and moves the adjacent pixel pitch distance of the spatial light modulator by an integer by one. Is reproduced by temporal synthesis. As a result, an image can be displayed with a resolution that is an integral multiple of the pixels of the spatial light modulator, and a projector can be constructed at low cost by using a spatial light modulator with coarse pixels and a simple optical system.
[0011]
However, in the example of Japanese Patent Laid-Open No. 5-313116, a pixel shift method is described in which the image display element itself is swung at a high speed by a distance smaller than the pixel pitch. In this method, the optical system is fixed. Therefore, the occurrence of chromatic aberration is small, but since the image display element itself needs to be translated accurately and at high speed, the accuracy and durability of the movable part is required, and vibration and sound become a problem.
[0012]
Further, according to Japanese Patent Laid-Open No. 6-324320, in order to improve the resolution of a display image apparently without increasing the number of pixels of an image display device such as an LCD, they are arranged in the vertical and horizontal directions. Each of the plurality of pixels emits light according to the display pixel pattern, and an optical member that changes the optical path for each field is disposed between the image display device on which the image is displayed and the observer or the screen. In addition, for each field, a display pixel pattern whose display position is shifted in accordance with the change of the optical path is displayed on the image display device. Here, the optical path is changed by causing the portions having different refractive indexes to appear alternately in the optical path between the image display device and the observer or the screen for each field of the image information. It is.
[0013]
In the above-mentioned Japanese Patent Application Laid-Open No. 6-324320, as a means for changing the optical path, a combination mechanism of an electro-optic element and a birefringent material, a lens shift mechanism, a vari-angle prism, a rotating mirror, a rotating glass, and the like are described. In addition to the above-mentioned system that combines the optical rotatory element and the birefringent element, the optical path is switched by displacing (translating, tilting) the optical elements such as a lens, a reflecting plate, and a birefringent plate by a voice coil, a piezoelectric element, However, in this method, since the optical element is driven, the configuration becomes complicated and the cost increases.
[0014]
Further, according to Japanese Patent Laid-Open No. 10-133135, a light beam deflecting device that can eliminate the need for a rotating machine element, can achieve overall downsizing, high accuracy and high resolution, and is hardly affected by external vibrations. Has been proposed. Specifically, a translucent piezoelectric element disposed on the light beam traveling path, a transparent electrode provided on the surface of the piezoelectric element, and a light beam incident surface and a light beam emitting surface of the piezoelectric element. Voltage applying means for applying a voltage to the piezoelectric element through the electrode in order to change the optical path length between them and deflect the optical axis of the light beam.
[0015]
In the example of Japanese Patent Laid-Open No. 10-133135, a method is proposed in which a light-transmitting piezoelectric element is sandwiched between transparent electrodes and a thickness is changed by applying a voltage to shift an optical path. There are the same problems as in the case of the above-mentioned JP-A-6-324320, such as requiring a transparent piezoelectric element and increasing the cost of the apparatus.
[0016]
Further, the applicant of the present invention has previously described a pair of transparent substrates, a liquid crystal comprising a chiral smectic C phase having a homeotropic orientation filled between the substrates, and at least one set of electric fields that cause an electric field to act on the liquid crystals. By using a liquid crystal composed of a chiral smectic C phase, the high cost, large equipment, light loss, and optical noise associated with the complicated structure of conventional optical deflection elements are improved. In addition, “light deflecting elements, light deflecting devices, and image display devices” that can improve the dullness of responsiveness in conventional smectic A liquid crystal, nematic liquid crystal, and the like and enable high-speed response have been proposed.
[0017]
[Problems to be solved by the invention]
When the above-mentioned problems of the prior art are arranged, the problem with the conventional pixel shift element is that
(1) High cost due to the complicated structure, large equipment, loss of light quantity, optical noise such as ghost, etc. or reduction in resolution,
(2) In particular, positional accuracy and durability in the case of a structure having a movable part, problems of vibration and sound,
(3) Low response speed in nematic liquid crystal, etc.
Etc.
[0018]
Regarding the response speed of (3), the speed of light deflection required for pixel shift in the image display device can be estimated as follows. Image field (time t_Field) In terms of time, and the optical path between the image display element and the optical member is deflected for each of n subfields to determine the pixel shift shift positions at n locations. Time t_{science fiction}Is
t_{science fiction}= T_Field/ N
It is represented by This time t_{science fiction}The light is deflected during the period of time t._shiftThen, this t_shiftSince the display cannot be performed during this period, the light use efficiency is reduced by an amount corresponding to this period.
[0019]
The light utilization efficiency E is expressed by the following formula.
E = (t_{science fiction}-T_shift) / T_{science fiction}
If the pixel shift position n is 4, the image field t_FieldIn order to ensure the light use efficiency E of 90% or more in the case of 16.7 ms,
0.9 <(16.7 / 4-t_shift) / (16.7 / 4)
t_shift<0.42 (ms)
Therefore, it is necessary to perform light deflection in 0.42 ms. Since a normal nematic liquid crystal has a response speed of several ms or more, it cannot be used as an optical element for high-speed pixel shift as shown here.
[0020]
In the invention described in Japanese Patent Application Laid-Open No. 6-18940, nematic liquid crystal is used as the liquid crystal material. Therefore, it is difficult to increase the response speed to sub-milliseconds, and it cannot be used for pixel shift. On the other hand, the response speed of a ferroelectric liquid crystal composed of a chiral smectic C phase can be sufficiently set to 0.42 ms or less.
In the invention described in JP-A-9-133904, a smectic A-phase ferroelectric liquid crystal is used. However, since the smectic A-phase does not have spontaneous polarization, a high speed such as that seen in a chiral smectic C-phase is used. I still can't expect the action.
[0021]
Therefore, the present invention basically improves the problem in the conventional optical deflection element, that is, the high cost, the size of the apparatus, the light loss, and the optical noise due to the complicated configuration, and the configuration is simple. An object of the present invention is to provide an optical deflecting device that is small in size, has little light loss, optical noise, resolution reduction, and can be reduced in cost, and an image display device including these.
[0022]
[Means for Solving the Problems]
The invention of claim 1 includes a pair of transparent substrates, an alignment film that homeotropically aligns liquid crystal molecules between the substrates, a liquid crystal layer that forms a chiral smectic C phase under no electric field, and a liquid crystal layer between the substrates. An optical path deflection element having at least two or more spacers that regulate the thickness of the liquid crystal layer, and at least two or more electrodes that generate an electric field in a direction substantially parallel to the liquid crystal layer, and an electric field direction between the electrodes. In the optical deflecting device, which has a voltage applying means capable of switching, and deflects the optical path of transmitted light in a direction substantially perpendicular to both the normal direction of the liquid crystal layer and the electric field direction by switching the direction of application of the electric field, the spacer Of these, at least two opposed spacers are made of a conductive material, and the surfaces opposed to the spacers are electrodes arranged substantially parallel to the direction of deflecting the optical path. There is provided a light deflector configuration.
[0023]
The invention of claim 2 comprises a pair of transparent substrates, an alignment film for homeotropic alignment of liquid crystal molecules between the substrates, a liquid crystal layer for forming a chiral smectic C phase under no electric field, and a liquid crystal layer between the substrates. An optical path deflection element having at least two or more spacers that regulate the thickness of the liquid crystal layer, and at least two or more electrodes that generate an electric field in a direction substantially parallel to the liquid crystal layer, and an electric field direction between the electrodes. An optical deflecting device for deflecting an optical path of transmitted light in a direction substantially perpendicular to both the normal direction of the liquid crystal layer and the electric field direction by switching an application direction of the electric field. The deflecting element has a plurality of electrode line groups arranged substantially parallel to a desired optical path shift direction in a region including the optical path on at least one substrate, and the voltage applying means An optical deflecting device capable of deflecting the entire optical path relatively uniformly even when the effective cross-sectional area of the optical path is large, wherein the voltage value applied to the electrode line is set to a different value stepwise. It is to provide.
[0024]
According to a third aspect of the present invention, in the second aspect of the present invention, the optical path deflecting element is a group of a plurality of electrode lines arranged substantially parallel to a desired optical path shift direction in a region including the optical paths on both substrates. The present invention provides an optical deflecting device capable of deflecting the entire optical path relatively uniformly and efficiently even when the effective cross-sectional area of the optical path is large.
[0025]
According to a fourth aspect of the present invention, in the third aspect of the invention, the electrode lines are made of a transparent electrode material, and the positions of the transparent electrode lines on each substrate are alternately arranged as viewed from the optical path, and each transparent electrode at a certain time The voltage value applied to the line is set to a different value stepwise alternately between the two substrates, and even when the effective cross-sectional area of the optical path is large, the uniformity of the deflection amount of the entire optical path is further increased. It is intended to increase.
[0026]
According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, the spacer is a pair of two electrodes made of a conductive material provided outside the region of the optical path, and the planar direction of the optical path deflecting element is The electrode line group is provided between the electrode pairs, and the voltage applying means applies a voltage value equal to or higher than the maximum voltage value applied to the electrode line group to one of the electrode pairs at a certain time, A voltage value equal to or lower than the lowest voltage value applied to the electrode line group is applied to the other of the electrode pairs, and even when the effective cross-sectional area of the optical path is large, the entire optical path can be uniformly deflected. An optical deflecting device that can be used is provided.
[0027]
According to a sixth aspect of the present invention, in any of the second to fifth aspects of the present invention, a dielectric layer is provided on the substrate surface on which the electrode line group is formed, and an alignment film is provided between the dielectric layer and the liquid crystal layer. The present invention is characterized in that even when the area of the optical path deflecting element is large, the electric field strength in the plane direction in the liquid crystal layer is made uniform, and a uniform optical path deflecting effect can be obtained.
[0028]
The invention of claim 7 is characterized in that, in the invention of claim 6, the dielectric layer is the alignment film, and the liquid crystal layer has a relatively simple layer structure even when the area of the optical path deflecting element is large. The electric field strength in the plane direction is made uniform, and a uniform optical path deflection effect can be obtained.
[0029]
  The invention of claim 8 is the invention according to any one of claims 1 to 7, wherein the polarization of incident light to the optical path deflecting element is changed.lightDeviation that matches the direction of the optical pathlightIt is characterized by having a direction control means, and the optical path is surely deflected even when the incident light is unpolarized light.
[0030]
  According to a ninth aspect of the present invention, in the eighth aspect of the invention, the polarization plane rotating means for rotating the polarization plane of the outgoing light of the optical path deflecting element at a substantially right angle, and the outgoing light after the polarization plane rotation is used as the incident light. The optical path deflection elementelementAnd the second optical path deflectionelementThe normal direction of the liquid crystal layer is almost the same, and both optical path deflectionselementIn other words, the optical path can be deflected in a two-dimensional direction.
[0031]
According to a tenth aspect of the present invention, there is provided 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 The light according to any one of claims 1 to 9, wherein an optical device for observing light, display drive means formed by a plurality of subfields obtained by dividing an image field in time, and light paths of emitted light from each pixel are deflected. And displaying an image pattern in which the display position is shifted in accordance with the deflection state of the optical path for each subfield, thereby multiplying and displaying the apparent number of pixels of the image display element. The present invention is characterized by providing an image display device that apparently has high definition and high light utilization efficiency using an image display element having a small number of pixels.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram for explaining a first embodiment of the present invention. FIG. 1 (A) is a top view, FIG. 1 (B) is a plan view, and FIG. 1 (A) is a cross-sectional view taken along the line CC of FIG. In this optical deflection element 1, first, as shown in the side view of FIG. 1C, a pair of transparent substrates 2 and 3 are provided so as to face each other. An alignment film 4 is formed on at least one of the inner surfaces of the substrate 2 here, and a liquid crystal layer 5 made of a ferroelectric liquid crystal composed of a chiral smectic C phase is formed between the alignment film 4 and the other substrate 3. Filled.
[0033]
With respect to the structure having such a pair of substrates 2 and 3 and the liquid crystal layer 5, as shown in the front view of FIG. A pair of electrodes is arranged and connected to a power source 7 as shown in FIG. As shown in the top view of FIG. 1A, the electrode pair 6a, 6b also functions as a spacer for regulating the thickness of the electric field applying means and the liquid crystal layer, and the light deflection element 1 is located at a position not overlapping the optical path. It is installed so that the electric field vector faces in a direction substantially perpendicular to the liquid crystal rotation axis. When it is desired to swing the traveling direction of light by light deflection in three or more directions, the incident light L₁And a plurality of electrode pairs 6a and 6b may be provided corresponding to these deflection directions. Incident light L₁Is deflected by the direction of the electric field formed by the electrode pairs 6a and 6b (the white arrow in FIG. 1A), and the first outgoing light Lo₁Alternatively, the second outgoing light Lo₂Any one of the optical paths is taken.
[0034]
Here, the liquid crystal layer 5 will be described. A “smectic liquid crystal” is a liquid crystal layer in which the long axis directions of liquid crystal molecules are arranged in layers. For such liquid crystals, the liquid crystal in which the normal direction of the layer (layer normal direction) and the major axis direction of the liquid crystal molecules coincide with each other is “smectic A phase”, and the liquid crystal that does not coincide with the normal direction is “smectic”. It is called “Phase C”. A ferroelectric liquid crystal composed of a smectic C phase generally has a so-called spiral structure in which the liquid crystal director direction is spirally rotated for each layer in the state where an external electric field does not work, and is called a “chiral smectic C phase”. In addition, the chiral smectic C reciprocal ferroelectric liquid crystal faces the direction in which the liquid crystal directors face each other. Since the liquid crystal composed of these chiral smectic C phases has an asymmetric carbon in the molecular structure and is spontaneously polarized by this, the liquid crystal molecules are rearranged in a direction determined by the spontaneous polarization Ps and the external electric field E. Optical properties are controlled. In the present embodiment and the like, the light deflection element 1 will be described by taking a ferroelectric liquid crystal as an example of the liquid crystal layer 5, but the same can be used for an antiferroelectric liquid crystal.
[0035]
The structure of a ferroelectric liquid crystal composed of a chiral smectic C phase is composed of a main chain, a spacer, a skeleton, a bonding part, a chiral part, and the like. As the main chain structure, polyacrylate, polymethacrylate, polysiloxane, polyoxyethylene and the like can be used. The spacer is for linking a skeleton, a bonding part, and a chiral part responsible for molecular rotation to the main chain, and a methylene chain having an appropriate length is selected. In addition, a —COO— bond or the like is selected as a bond portion that connects a chiral (chiral) portion and a rigid skeleton such as a biphenyl structure.
[0036]
In the optical deflecting element 1 of the present embodiment, the ferroelectric liquid crystal 5 made of a chiral smectic C phase is oriented so that the rotation axis of the molecular helix rotation is perpendicular to the surfaces of the substrates 2 and 3 by the alignment film 4, so-called homeotropic alignment. Make. As an alignment method for such homeotropic alignment, a conventionally performed method can be applied. That is, (1) shear stress method, (2) magnetic field orientation method, (3) temperature gradient method, (4) SiO oblique deposition method, (5) photo-alignment method, etc. (for example, Takezoe, Fukuda “strong” Structure and physical properties of dielectric liquid crystal "(see Corona, p235).
[0037]
One of the features of the optical deflection element 1 of the present embodiment is that the configuration is simple and the manufacturing cost can be suppressed. In addition, the chiral smectic C phase has an extremely high speed response compared to the smectic A phase and nematic liquid crystal, and is characterized in that switching at sub ms is possible. In particular, since the liquid crystal director direction is uniquely determined with respect to the electric field direction, control of the director direction is easier and easier to handle than a liquid crystal composed of a smectic A phase.
[0038]
The liquid crystal layer 5 made of a chiral smectic C phase forming homeotopic alignment is more effective in the operation of the liquid crystal director than in the case where the liquid crystal director is in a homogeneous alignment (the liquid crystal director is aligned parallel to the substrate surface). Therefore, it is easy to control the light deflection direction by adjusting the direction of the external electric field, and has the advantage that the required electric field is low. Further, when the liquid crystal directors are homogeneously oriented, the liquid crystal directors strongly depend not only on the direction of the electric field but also on the substrate surface, so that more positional accuracy is required for the installation of the light deflection element. Conversely, in the case of homeotopic orientation as in the present embodiment, the setting margin of the optical deflection element 1 increases with respect to optical deflection. In making use of these features, it is not necessary that the spiral axis be strictly oriented perpendicular to the substrate surface, and it may be tilted to some extent. It suffices if the liquid crystal director can face two directions without receiving the regulating force from the substrates 2 and 3.
[0039]
Next, with reference to FIG. 2 and FIG. 3, the operation principle of the optical deflection element 1 of the present embodiment will be described. FIG. 2 schematically shows the alignment state of the liquid crystal molecules with respect to the configuration shown in FIG. In FIG. 2, for the sake of convenience, a voltage is applied in the front and back direction of the paper, and the electric field is generated in the front and back direction of the paper. The electric field direction is switched by the power source 7 in accordance with the target light deflection direction. Further, the incident light with respect to the light deflection element 1 is linearly polarized light, and its deflection direction is the vertical direction as shown by the upper and lower arrows in FIG. 2, and the spacer / electrodes 6a and 6b have an electric field direction in the deflection direction. Oppositely arranged so as to be orthogonal. Although not shown, it is preferable to provide an electromagnetic shield so that the leakage electric field from the electrodes 6a and 6b does not adversely affect the devices around the optical deflection element 1.
[0040]
In FIG. 2, when the XYZ orthogonal coordinate system is taken as shown, in the XZ section in the liquid crystal layer 5, as shown in FIG.₁Or second orientation state 8₂Any one of the states (see FIG. 3B) is distributed. θ is the tilt angle of the liquid crystal director 8 from the liquid crystal rotation axis, and is simply referred to as “tilt angle” hereinafter. Assuming that the spontaneous polarization Ps of the liquid crystal molecules is positive and the electric field E is applied in the positive Y-axis direction (upward on the paper surface), the liquid crystal director 8 is in the XZ plane because the liquid crystal rotation axis is substantially perpendicular to the substrate. When the refractive index in the major axis direction of the liquid crystal molecule is ne and the refractive index in the minor axis direction is no, as the incident light, the linearly polarized light having the deflection direction in the Y axis direction is selected, and when the incident light advances in the X axis positive direction, The light travels straight in the liquid crystal layer 5 as a normal light upon receiving the refractive index no, and proceeds in the direction a in FIG. That is, no light deflection is received.
[0041]
On the other hand, when linearly polarized light whose deflection direction is the Z-axis direction is incident, the refractive index in the incident direction is obtained from both the direction of the liquid crystal director 8 and the refractive indexes no and ne. More specifically, the refractive index ellipsoid having the refractive indexes no and ne as main axes is obtained from the relationship with the direction of light passing through the center of the ellipsoid, but the details are omitted here. The light is deflected corresponding to the refractive indexes no and ne and the direction of the liquid crystal director 8 (inclination angle θ), and shifted in the direction shown in FIG. 3A (in the case of the first alignment state).
[0042]
When the thickness (gap) of the liquid crystal layer 5 is d, the shift amount S is expressed by the following equation (see, for example, “Crystal Optics” Applied Physics Society, Optical Society, p198).
S = [(1 / no)²− (1 / ne)²] sin (2θ ・ d)
÷ [2 ((1 / ne)²sin²θ + (1 / no)²cos²θ)] ……… Equation 1
When the electric field direction is reversed, the liquid crystal director 8 takes a linearly symmetrical arrangement (second alignment state) about the X axis in FIG. 3 and linearly polarized light whose deflection direction is the Z axis direction. The traveling direction is as shown by b 'in FIG.
Therefore, by controlling the direction of the electric field applied to the liquid crystal 5 with respect to this linearly polarized light, it is possible to deflect light at two positions b and b ′, that is, 2S.
[0043]
For example, when the light deflection amount S is calculated for the light deflection amount obtained with respect to the representative physical property values (no = 1.6, ne = 1.8) of the material of the liquid crystal 5, the tilt angle θ of the liquid crystal director 8 is When 22.5 ° and the liquid crystal thickness is 32 μm, a deflection amount of 2S = 5 (μm) is obtained. Further, in homeotropic alignment ferroelectric liquid crystal, a response speed of 0.1 ms is reported with respect to an electric field of about 700 V / cm (Ozaki et al., JJ Appl. Physics, Vol. 30, No. 9B, pp 2366-2368 (1991)), a sufficiently high response speed of sub ms order is obtained.
Further, in a liquid crystal composed of a chiral smectic C phase, the tilt angle θ varies with temperature T, and θ∝ (T−Tc) where Tc is the phase transition point.^βThere is a relationship. β varies depending on the material, but takes a value of about 0.5. It is also possible to control the amount of light deflection by temperature control utilizing this characteristic.
[0044]
For example, suppose that the above-mentioned 22.5 ° is set as the inclination angle θ, and the temperature corresponding to this is set to T_{θ = 22.5 °}Then, T> T_{θ = 22.5 °}Then, θ <22.5 ° and T <T_{θ = 22.5 °}Since θ> 22.5 °, the inclination angle θ can be controlled by temperature, and the amount of light deflection can be controlled by this. As for position control, fine adjustment by an electric field can be performed in the same manner, and appropriate light deflection can be achieved by temperature, electric field, or a combination of both.
[0045]
In FIG. 1, when an electric field is applied in the direction of the electrodes 6a to 6b, the first outgoing light Lo₁When the electric field is applied in the direction from the electrodes 6b to 6a, the second outgoing light Lo₂It becomes. The optical path can be shifted by switching the direction of the electric field at high speed by the AC power source 7. In addition, the opposing surface of the spacer that regulates the thickness of the liquid crystal layer is arranged in parallel to the direction of deflecting the optical path, and this spacer also serves as an electrode that applies an electric field to the liquid crystal layer in the plane direction. An optical deflecting element having a simple configuration can be realized.
[0046]
In the above configuration, since the electrodes are provided only at both ends of the element, if the effective area of the element is increased and the distance between the electrodes is increased, the distance between the electrodes is sufficiently larger than the width of the electrode. It becomes difficult to apply a uniform electric field strength within the layer. Therefore, the electric field strength in the plane direction of the liquid crystal layer becomes non-uniform, and it becomes difficult to obtain uniform optical path deflection within the element.
[0047]
4A and 4B are diagrams for explaining a second embodiment of the present invention. FIG. 4A is a top view, FIG. 4B is a front view, and FIG. In FIG. 3A, a cross-sectional view taken along the line CC of FIG. 3A, the width of the element is set larger than that of the configuration of FIG. 1, and an electrode line 9 is provided on at least one substrate surface. In this case, it is not necessary that the spacers 10 at both ends of the element also serve as electrodes. The alignment film 4 may also be provided on the substrate surface on which the electrode lines 9 are provided. Although eight electrode lines 9 are provided in FIG. 4, the voltage application means 11 is configured so that the applied voltage increases or decreases stepwise from the leftmost electrode line in the figure. For example, by dividing the voltage supplied from the power supply 7 by the seven resistors 12 and connecting the resistors to the electrode lines 9, a stepwise voltage value can be applied. The stepwise voltage application method is not limited to this configuration, and may be a configuration in which a plurality of power supplies are directly connected to each electrode. The number of electrode lines, the line width, the line interval, the potential difference between the electrode lines, and the like are appropriately set based on the desired optical path size, optical path deflection amount, and the like. In this configuration, since a potential gradient is forcibly created inside a relatively wide liquid crystal layer, it is possible to obtain a relatively uniform electric field strength macroscopically over the entire surface of the device.
[0048]
However, since the potentials of the electrode line width portions are equal, when viewed microscopically, a desired potential gradient cannot be obtained in the vicinity of the electrode line, and a desired optical path deflection effect cannot be obtained. Therefore, in this configuration, an optical path deflecting element having an area other than the vicinity of the electrode line can be obtained. In this case, it is preferable to provide a light blocking member that blocks light transmitted through the vicinity of the electrode, or incident light is divided in advance corresponding to the effective area. For example, when applied to an image display device, it is preferable to match the pixel pitch and the electrode line pitch so that the electrode line portion corresponds between the pixels. In FIG. 4, seven optical paths are incident correspondingly between the electrode lines, and the direction of the electric field is switched by the voltage application means, so that the seven optical paths can be simultaneously shifted in the same direction.
[0049]
Therefore, in the example shown in FIG. 4, a plurality of electrode lines are provided in the optical path region through which desired light of the optical path deflecting element is transmitted, and the voltage value applied to each electrode line is changed stepwise from the end side, Even when the effective cross-sectional area of the optical path is large, a macroscopically gradual potential gradient can be created in the plane direction in the liquid crystal layer over the entire region of the electrode line group. Therefore, it is possible to obtain at least discrete effective portions in which a desired electric field strength is formed in the liquid crystal layer over the entire optical path region. By using only this effective portion, the entire optical path having a large cross-sectional area can be deflected relatively uniformly.
[0050]
In the example shown in FIG. 4, electrode lines are provided only on one substrate for the sake of simplification of the configuration. However, in this configuration, an electric field may be generated in the film thickness direction of the liquid crystal layer. When the electric field in the film thickness direction of the liquid crystal layer 5 increases, the liquid crystal director direction becomes nonuniform in the thickness direction of the liquid crystal layer, and a desired optical path deflection amount cannot be obtained with respect to the liquid crystal film thickness. Therefore, a form as shown in FIG. 5 is proposed.
[0051]
FIG. 5 is a view for explaining a third embodiment of the present invention. In FIG. 5, the electrode lines 9 are provided so as to face each other in the region including the optical path on both substrates. Here, the alignment film 4 is provided on both substrates, but it may be a single side. A voltage is applied stepwise from the electrode line 9 at the end by voltage application means (not shown). At this time, it is set so that the same potential is applied to the electrode pair directly facing. Since the same potential is applied to the upper and lower interfaces of the liquid crystal layer, the potential distribution in the film thickness direction of the liquid crystal layer, that is, the electric field strength is reduced, and a desired inclination of the liquid crystal molecules can be obtained over the entire liquid crystal layer, which is efficient. Optical path deflection can be performed. That is, since the electrode lines are provided on the substrates on both sides, the potential distribution in the thickness direction of the liquid crystal layer becomes relatively uniform even when the effective cross-sectional area of the optical path is large, and the electric field in the thickness direction of the liquid crystal layer Since the strength can be reduced, the director direction of the liquid crystal molecules when an electric field is applied becomes relatively uniform in the thickness direction of the liquid crystal layer, and the entire optical path can be deflected relatively uniformly and efficiently.
[0052]
In the above example, the number of electrode lines is relatively small, but in order to obtain a more uniform electric field intensity distribution with a relatively large area optical path deflecting element, the width of the electrode lines should be as narrow as possible. It is preferable to narrow the pitch. However, the number of lines themselves increases, the stepwise voltage application means becomes complicated, and it becomes difficult to take out the wiring from the substrate. Therefore, it is preferable to reduce the number of lines on one substrate. Therefore, in practice, the line pitch interval is set to be wide, but if the line pitch interval is wide, a potential portion lower than the set potentials of both lines may be generated near the middle between the lines. . That is, a part where an electric field in the opposite direction acts on a part between the lines is generated.
[0053]
FIG. 6 is a diagram for explaining a fourth embodiment of the present invention. FIG. 6 (A) is a top view, FIG. 6 (B) is a front view, and in the configuration of FIG. Formed on both substrates, the positions of the electrode lines 9 on each substrate are alternately arranged. Then, voltage application means for alternately setting different values stepwise between both substrates so that the applied voltage gradually increases or decreases from the leftmost electrode line in the front view shown in FIG. 6B. 11 is configured. FIG. 6 shows a method using the series resistor 12 as in FIG. 4, but is not limited to this method. In this configuration, since the desired potential in the vicinity of the middle between the electrode lines on one side is forcibly applied to the electrode lines on the other substrate, the generation of the reverse electric field as described above can be prevented. In addition, since an electric field is generated in the vicinity of the electrode line due to a potential difference between the electrode lines near the opposite substrate, the electrode line portion can also obtain an optical path deflection effect. Therefore, in the present embodiment, it is preferable to form the electrode line with a transparent electrode material such as ITO. Since the transparent electrode line can also function as an optical path deflection region, an optical path having a large cross-sectional area can be deflected relatively uniformly. In addition, since the number of lines on a single substrate can be designed to be small, wiring connection and the like are relatively easy.
[0054]
As described above, when the distance between the electrode lines is wide, a portion with a low potential occurs near the middle between the lines, and an electric field in the reverse direction acts. However, the electrode lines are alternately arranged on the upper and lower substrates. By applying the voltage value alternately, even if the effective cross-sectional area of the optical path is large, the potential change in the surface direction in the liquid crystal layer becomes relatively uniform, and the generation of a reverse electric field is generated. Furthermore, by using a transparent material for the electrode, the electrode line can also function as an optical path deflection region. Therefore, the optical path having a large cross-sectional area can be deflected relatively uniformly.
[0055]
FIG. 7 is a diagram for explaining a fifth embodiment of the present invention. In FIG. 7, the spacer having the configuration of FIG. 4 is an electrode pair 13a, 13b made of a conductive material. A voltage value equal to or higher than the maximum voltage value applied to the electrode line group is applied to one of 13b, and a voltage value equal to or lower than the lowest voltage value applied to the electrode line group is applied to the other electrode pair. In the example of FIG. 7, the power source 7b connected to the electrodes serving as spacers at both ends is provided independently. However, the power source 7a connected to the electrode line group may be shared. The voltage value applied to both ends is set in consideration of the influence of the leakage electric field on the periphery of the element. The polarity switching timing is synchronized with the polarity switching of the voltage applied to the electrode line 9. Even if the potential gradient in the plane direction in the liquid crystal layer due to the electrode line group is set to be non-uniform, by applying an auxiliary voltage between the electrodes serving as spacers at both ends, Therefore, the optical path having a large cross-sectional area can be deflected relatively uniformly. In addition, in order to make an electrode line function also as an optical path deflection | deviation area | region, it is preferable that it is a transparent electrode line.
[0056]
As described above, in addition to the stepwise potential application by the electrode line in the optical path region, an auxiliary voltage is applied even when the effective cross-sectional area of the optical path is large by the electrode also serving as a spacer member outside the optical path region. Since the potential gradient in the plane direction in the liquid crystal layer is smoothed, the optical path having a large cross-sectional area can be deflected relatively uniformly.
[0057]
FIG. 8 is a diagram for explaining a sixth embodiment of the present invention. As shown in the figure, a dielectric layer 14 is provided on substrates 2 and 3 on which electrode line groups are formed, and the dielectric layer 14 is provided. An alignment film 4 is provided between the liquid crystal layer 5 and the dielectric layer 14 can be made of a highly transparent material such as glass or resin. In addition, since an alignment film for homeotropic alignment is provided between the dielectric layer 14 and the liquid crystal layer 5, it is preferable to set a formation method that does not deteriorate the dielectric layer when forming the alignment film. In particular, when the dielectric layer and the alignment film are made of resin, it is necessary to optimize the coating solvent for both. By sandwiching the dielectric layer 14 between the formation surface of the electrode line 9 and the liquid crystal layer 5, the discontinuous potential distribution applied to the electrode line 9 becomes dull, and the potential gradient in the plane direction in the liquid crystal layer is uniform. Become.
[0058]
Therefore, the electric field intensity distribution in the plane direction in the liquid crystal layer becomes uniform, and uniform optical path deflection can be obtained. Also in this configuration, the spacer is preferably the electrode pair 13a, 13b made of a conductive material. In addition, in order to make an electrode line function also as an optical path deflection | deviation area | region, it is preferable that it is a transparent electrode line. However, in this configuration, there is a problem that the element creation process becomes complicated.
[0059]
FIG. 9 is a diagram for explaining a seventh embodiment of the present invention. In FIG. 9, a relatively thick alignment film 4 is provided on a substrate provided with electrode lines, and the dielectric layer is formed on the alignment film 4. It is trying to have the function of. Since the layer structure of the element is simple, the manufacturing process can be simplified. In addition, in order to make an electrode line function also as an optical path deflection | deviation area | region, it is preferable that it is a transparent electrode line.
[0060]
In the first to seventh embodiments described above, only the linearly polarized light in the deflection direction of the optical path, that is, the polarization direction parallel to the tilt direction of the liquid crystal molecules when the electric field is applied receives the deflection of the optical path and is orthogonal thereto. Linearly polarized light remains straight. Therefore, when non-polarized light is incident, since the outgoing light includes a component that is not deflected, the contrast with respect to the presence or absence of optical path deflection is lowered.
[0061]
  Therefore, in the eighth embodiment of the present invention, the polarization of incident light on the optical path deflecting element is reduced.lightDeviation that matches the direction of the optical pathlightDirection control means is provided. sidelightA linear polarizing plate can be used as the direction control means. The linear polarizing plate is set on the incident surface side of the element so that the deflection direction of the linear polarizing plate is aligned parallel to the longitudinal direction of the transparent electrode line or the spacer electrode. Even when the incident light is non-polarized light, the light component that is not subjected to the optical path deflection action due to the tilt of the liquid crystal molecules is cut, so that the optical switching by the optical path deflection can be surely performed. Since only the light in the deflection direction of the optical path, that is, the light in the deflection direction parallel to the tilt direction of the liquid crystal molecules at the time of applying an electric field is incident, generation of light that is not deflected can be prevented, and reliable optical path deflection can be realized.
[0062]
FIG. 10 is a diagram for explaining a ninth embodiment of the present invention. The embodiment shown in FIG. 10 includes two optical deflection elements 1A and 1B configured as in the above-described embodiment. The present invention relates to an optical deflection element 16 configured by combining a half-wave plate 15. In FIG. 10, spacers, transparent electrode lines, alignment films, and the like are omitted. The light deflection elements 1A and 1B are arranged in series in the light traveling direction with the electric field generation directions by the respective electrode pairs 6a and 6b orthogonal to each other, and a half-wave plate 15 is interposed between these light deflection elements 1A and 1B. It is arranged. As the half-wave plate 15, a commercially available one for visible light can be applied as it is. As shown in FIG. 10, the light incident on this light deflection element has a deflection direction in the Z-axis direction, and in the vertical direction (Z-axis direction) in the light deflection element 1A on the preceding stage with respect to the light traveling direction. After receiving the deflection, the deflection direction is rotated by 90 ° by the half-wave plate 15 to obtain the deflection direction in the Y-axis direction, so that the subsequent optical deflection element 1B receives the deflection in the left-right direction (Y-axis direction). . According to such an optical deflection element 16, the optical deflection is performed at two positions in the vertical direction (Z-axis direction) in the optical deflection element 1A and at two positions in the horizontal direction (Y-axis direction) in the optical deflection element 1B. As a whole element, light can be shifted to a total of four positions.
[0063]
FIG. 11 is a diagram for explaining a tenth embodiment of the present invention, and this embodiment shows an example applied to an image display apparatus. In FIG. 11, reference numeral 21 denotes a light source in which LED lamps are arranged in a two-dimensional array. In the traveling direction of light emitted from the light source 21 toward the screen 26, a diffusion plate 22, a condenser lens 23, and an image display element are used. A transmissive liquid crystal panel 24 and a projection lens 25 as an optical member for observing the image pattern are sequentially arranged. Reference numeral 27 denotes a light source drive unit for the light source 21, and reference numeral 28 denotes a drive unit for the transmissive liquid crystal panel 24. Here, on the optical path between the transmissive liquid crystal panel 24 and the projection lens 25, the light deflecting means 30 functioning as a pixel shift element is interposed and connected to the drive unit 31. As such an optical deflection means 30, the optical deflection element 1 as described above is used.
[0064]
The illumination light that is controlled by the light source drive unit 27 and emitted from the light source 21 becomes illumination light that is made uniform by the diffuser plate 22, and is controlled by the condenser lens 23 in synchronization with the illumination light source by the liquid crystal drive unit 28 to be a transmission type. The liquid crystal panel 24 is critically illuminated. The illumination light spatially modulated by the transmissive liquid crystal panel 24 enters the light deflector 30 as image light, and the image light is shifted by an arbitrary distance in the pixel arrangement direction by the light deflector 30. This light is magnified by the projection lens 25 and projected onto the screen 26.
[0065]
An image pattern in which the display position is shifted in accordance with the deflection of the optical path for each of the plurality of subfields obtained by temporally dividing the image field by the light deflecting unit 30 is displayed. The number of apparent pixels is multiplied and displayed. Thus, the amount of shift by the light deflecting means 30 is set to ½ of the pixel pitch because image multiplication is performed twice as much as the pixel arrangement direction of the transmissive liquid crystal panel 24. By correcting the image signal for driving the transmissive liquid crystal panel 24 by the shift amount according to the shift amount, an apparently high-definition image can be displayed. At this time, since the light deflecting element as in each of the above-described embodiments is used as the light deflecting means 30, the light use efficiency is improved and the observer is brighter and higher quality without increasing the load on the light source. Can provide images. By performing the optical deflection position control based on the electric field application direction and the electric field intensity by the electrode pairs 6a and 6b in the optical deflection element 1, an appropriate pixel shift amount can be maintained and a good image can be obtained.
[0066]
Example 1
The surface of a glass substrate having a size of 3 cm × 4 cm and a thickness of 3 mm was treated with a silane coupling agent (AY43-021 made by Toray, Dow Corning, Silicone) to form a vertical alignment film. Using two aluminum electrode sheets having a thickness of 50 μm, a width of 1 mm, and a length of 3 cm as spacers, two glass substrates were bonded together with the vertical alignment film as the inner surface. The two aluminum electrode sheets were parallel and the interval was 1 mm. In a state where the substrate was heated to about 90 degrees, ferroelectric liquid crystal (CS1029 manufactured by Chisso) was injected between the two substrates by a capillary method. After cooling, it was sealed with an adhesive to produce an optical path deflecting element similar to FIG. A line / space mask pattern having a width of 5 μm was provided on the incident surface side of the optical path deflecting element, and illumination was performed with linearly polarized light through this mask pattern. The direction of linearly polarized light was set to be the same as the longitudinal direction of the aluminum electrode sheet.
[0067]
The light transmitted through the mask pattern was observed with a microscope through the two aluminum electrode sheets of the optical path deflecting element. The mask pattern was observed as it was when no electric field was applied. When one of the two aluminum electrode sheets was grounded and a voltage of +100 V was applied to the other, the line / space pattern was observed with a shift of about 2.5 μm in the longitudinal direction of the aluminum electrode sheet. Since the mask pattern, the optical path deflecting element, and the microscope are mechanically stationary, it has been confirmed that the optical path shifts electrically. When a voltage of −100 V was applied to the other side, it shifted about 2.5 μm in the reverse direction. When a square wave voltage of ± 100 V was applied using a pulse generator and a high-speed power amplifier, an optical path shift of about 5 μm was confirmed from peak to peak. Since the width of the line / space was 5 μm, it was observed as if the brightness of the line and space were reversed. That is, if the space portion having a width of 5 μm is used as a light valve pixel, it can be confirmed that one pixel is apparently multiplied to two pixels by an optical path deflecting element having a simple configuration.
[0068]
Further, as a result of measuring the response speed by heating the temperature of the device to about 40 ° C., it was about 0.3 msec, which was confirmed to be sufficiently faster than the nematic liquid crystal. The response speed is confirmed by measuring the change in the amount of transmitted light over time while the electrode direction of the element is rotated 45 degrees during the crossed Nicols of the linear polarizer and the element is tilted about 10 degrees with respect to the optical path. And asked.
[0069]
In addition, the potential distribution and electric field distribution in the plane direction in the liquid crystal layer of this element were obtained by two-dimensional electric field simulation by the difference method. The calculation mesh size was 10 μm in length and width, the relative dielectric constant of the liquid crystal layer was 10, and the relative dielectric constant of the glass substrate was 8. In the calculation, the presence of the alignment film was omitted. FIG. 12 shows the potential distribution at the center of the liquid crystal layer, and FIG. 13 shows the electric field strength in the lateral direction at the center of the liquid crystal layer. The electric field strength is large near the electrodes at both ends, but a relatively uniform electric field strength is obtained near the center.
[0070]
(Comparative Example 1)
The same procedure as in Example 1 was performed except that the distance between the two aluminum electrode sheets was 2 mm and the applied voltage was 200 V. The average electric field strength between the electrodes was 100 V / mm, which was the same as in Example 1. However, the optical path shift amount in the vicinity of 0.5 mm from the line electrode on the ground side was as small as about 3 μm. In that part, the response speed was also slow, about 0.5 msec. Here, as a result of performing a two-dimensional electric field simulation under the same calculation conditions as in Example 1, the nonuniformity of the electric field strength in the lateral direction at the center of the liquid crystal layer is further increased as shown in FIG. It turned out that it became small at 0.5 mm vicinity from the ground electrode. In the structure of Example 1, it turned out that it is disadvantageous when the distance between electrodes is large.
[0071]
(Example 2)
An electrode line by aluminum deposition was formed on the surface of a glass substrate having a size of 3 cm × 4 cm and a thickness of 3 mm. The line width was 10 μm, the line pitch was 100 μm, the line length was 2 cm, and 20 aluminum electrode lines were formed in the width of 2 mm. One end of the line was made larger in width and pitch to get contact from the power source. A substrate having no electrode on the aluminum electrode line was treated with a silane coupling agent (AY43-021 made by Toray Dow Corning Silicone) to form a vertical alignment film. Using a Mylar sheet having a thickness of 50 μm, a width of 1 mm, and a length of 3 cm as a spacer, two glass substrates with and without a line electrode were bonded together with the vertical alignment film as the inner surface. The two mylar sheets were parallel and the distance between them was 2 mm. In a state where the substrate was heated to about 90 degrees, ferroelectric liquid crystal (CS1029 manufactured by Chisso) was injected between the two substrates by a capillary method. After cooling, it was sealed with an adhesive to produce an optical path deflecting element similar to FIG. A line / space mask pattern having a width of 5 μm was provided on the incident surface side of the optical path deflecting element, and illumination was performed with linearly polarized light through this mask pattern. The direction of linearly polarized light was set to be the same as the longitudinal direction of the aluminum electrode line.
[0072]
The light transmitted through the mask pattern was observed with a microscope through the vicinity of the center between the aluminum electrode lines of the optical path deflecting element. The mask pattern was observed as it was when no electric field was applied. Conductive wires were connected to one end of the 20 aluminum electrode lines, and connected between the series resistors as shown in FIG. Each resistance value was 1 MΩ, and 19 resistors were connected in series. When a square wave voltage of ± 200 V was applied to both ends of the series resistor using a pulse generator and a high-speed power amplifier, an optical path shift of about 4.5 μm was confirmed from peak to peak. The same optical path shift amount and a response speed of about 0.35 msec were confirmed between all the aluminum electrode lines.
[0073]
As a result of performing a two-dimensional electric field simulation under the same calculation conditions as in Example 1, the potential distribution and electric field distribution shown in FIGS. 15 and 16 were obtained in the central portion of the liquid crystal layer. In FIG. 16, the strength of the electric field strength is observed. However, in the above configuration, only a portion with a strong electric field strength is used as the optical path, so that a uniform optical path deflection region is obtained although it is discrete within the 2 mm width region. It is thought that it was possible.
[0074]
(Example 3)
As shown in FIG. 5, the same procedure as in Example 2 was performed except that 20 aluminum electrode lines were provided on both the upper and lower substrates and the aluminum electrode lines on both substrates were aligned with the optical path direction. The wires from the aluminum electrode lines on both substrates were connected between 19 series resistors so that the same potential was applied to the directly facing aluminum electrode lines. When a square wave voltage of ± 200V is applied to both ends of the series resistor using a pulse generator and a high-speed power amplifier, the optical path shift amount is almost uniform between all aluminum electrode lines and the response speed is about 0.3 msec. Was confirmed.
[0075]
As a result of performing a two-dimensional electric field simulation under the same calculation conditions as in Example 2, the electric field distribution shown in FIG. 17 was obtained at the center of the liquid crystal layer. This is almost the same as the electric field distribution in the horizontal direction of FIG. 16, but the uniformity of the electric potential and electric field in the film thickness direction is improved, so that the optical path shift amount is larger and the response speed is larger than in Example 2. became.
[0076]
Example 4
The electrode lines on both substrates were changed to ITO transparent electrode material, and as shown in FIG. 6, cells were prepared in the same manner as in Example 3 except that the transparent electrode lines on both substrates were alternately arranged in the optical path direction.
Using resistors having half the resistance value used in Example 3, 38 doubles were connected in series, and wirings from the transparent electrode lines of both substrates were alternately connected between the resistors. When a square wave voltage of ± 200 V is applied to both ends of the series resistor using a pulse generator and a high-speed power amplifier, the area other than about 0.2 mm from the both ends of the 2 mm wide optical path deflecting element is on the transparent electrode line. However, an optical path shift amount of about 5 μm and a response speed of about 0.3 msec were confirmed. With this configuration, an optical path shifting effect was obtained not only between the transparent electrode lines but also on the lines.
[0077]
As a result of performing a two-dimensional electric field simulation under the same calculation conditions as in Example 4, the voltage distribution and electric field distribution shown in FIGS. 18 and 19 were obtained in the central part of the liquid crystal layer. In this configuration, it was found that a low electric field or a reverse electric field was generated near the spacer. However, other than that, although the amplitude of the electric field strength was observed, it was found that a relatively uniform electric field strength was obtained on average.
[0078]
(Example 5)
The spacer member of the Mylar sheet was made the same aluminum electrode sheet as in Example 1, and as shown in FIG. When a square wave voltage of ± 200 V is applied to both ends of the series resistor and the aluminum electrode sheet using a pulse generator and a high-speed power amplifier, an optical path shift amount of about 5 μm is obtained in the entire region of the optical path deflecting element portion having a width of 2 mm. A response speed of 0.3 msec was confirmed.
[0079]
As a result of performing a two-dimensional electric field simulation under the same calculation conditions as in Example 5, the voltage distribution and electric field distribution shown in FIGS. 20 and 21 were obtained in the central portion of the liquid crystal layer. In this configuration, it was found that a relatively uniform electric field was generated even near the spacer.
[0080]
(Example 6)
Using a substrate similar to that of Example 5, a 50 μm thick Mylar sheet subjected to a hard coat treatment was bonded to the formation surface of the ITO transparent electrode line. A commercially available alignment film for vertical alignment liquid crystal was applied on a mylar sheet to obtain a substrate. A cell was prepared in the same manner as in Example 5, and each ITO transparent electrode line was connected to a series resistor. When a square wave voltage of ± 200 V was applied to both ends of the series resistor and the aluminum electrode sheet using a pulse generator and a high-speed power amplifier, an optical path shift amount of about 5 μm was obtained in the entire region of the optical path deflecting element having a width of 2 mm. A response speed of 0.3 msec was confirmed.
[0081]
As a result of conducting a two-dimensional electric field simulation under the same calculation conditions as in Example 5 with the relative permittivity of the Mylar sheet being 3.0, the voltage distribution and electric field distribution shown in FIGS. 22 and 23 were obtained at the center of the liquid crystal layer. . In this configuration, although an increase in the electric field strength was observed in the vicinity of the spacer, it was found that a very uniform lateral electric field was generated near the center of the element.
[0082]
(Example 7)
An image display device as shown in FIG. 11 was produced. A 0.9-inch diagonal XGA (1024 × 768 dots) polysilicon TFT liquid crystal panel was used as the image display element. The pixel pitch is about 18 μm both vertically and horizontally. The aperture ratio of the pixel is about 50%. Further, a microlens array is provided on the light source side of the image display element to increase the collection rate of illumination light. In this embodiment, an RGB three-color LED light source is used as a light source, and a so-called field sequential method is adopted in which color display is performed by switching the color of light applied to the one liquid crystal panel at a high speed.
[0083]
In this embodiment, it is assumed that the frame frequency of image display is 60 Hz, and the subfield frequency for quadruple pixel multiplication by pixel shift is 240 Hz which is four times. In order to further divide one subframe into three colors, an image corresponding to each color is switched at 720 Hz. A full color image can be seen by an observer by turning ON / OFF the LED light source of the corresponding color in accordance with the display timing of each color image on the liquid crystal panel.
[0084]
The basic configuration of the optical deflecting element is the same as that in Example 6, but the number of transparent electrode lines was 200 times 200, and the effective area width was 10 times 20 mm. The thickness of the aluminum electrode sheet serving as a spacer was set to 100 μm, and the optical path shift amount was set to about 9 μm. Also, the number of series resistors was increased 10 times, and a square wave voltage of ± 2000 V could be applied to both ends of the series resistors and the aluminum electrode sheet using a pulse generator and a high-speed power amplifier. Two of these elements were used, the incident side being the first optical path deflection element and the exit side being the second optical path deflection element. The transparent electrode lines are arranged so that the directions of the transparent electrode lines are orthogonal to each other and coincide with the pixel arrangement direction of the image display element.
[0085]
Further, a polarization plane rotating element is provided between the first and second optical path deflecting elements. The polarization plane rotating element was formed by spin-coating a polyimide alignment material on a thin glass substrate (3 cm × 4 cm, thickness 0.15 mm) to form an alignment film of about 0.1 μm. A rubbing treatment was performed after the annealing treatment of the glass substrate. An empty cell was fabricated by sandwiching an 8 μm thick spacer between the two glass substrates and pasting the upper and lower substrates so that the rubbing directions were orthogonal. Into this cell, a nematic liquid crystal having a positive dielectric anisotropy and an appropriate amount of a chiral material mixed was injected under normal pressure to produce a TN liquid crystal cell in which the orientation of liquid crystal molecules was twisted by 90 degrees. Since this cell is not provided with an electrode, it functions as a simple polarization plane rotation element.
[0086]
The polarizing plane of the light emitted from the first optical path deflecting element and the rubbing direction of the incident plane of the polarizing plane rotating element are arranged so as to be sandwiched between the two optical path deflecting means. The polarization plane of the light emitted from the first optical path deflection element is rotated by 90 degrees by the polarization plane rotation element, and coincides with the deflection direction of the second optical path deflection element. An optical path deflecting device comprising a first deflecting element, a polarization plane rotating element, and a second deflecting element was installed immediately after the liquid crystal light valve. In this embodiment, the light emitted from the liquid crystal display element is already linearly polarized light, and the deflection direction thereof is arranged to coincide with the optical path deflection direction of the first optical path deflection element. In order to ensure the degree of polarization of incident light, a linearly polarizing plate was provided on the incident surface side of the optical path deflecting element.
[0087]
The frequency of the rectangular wave voltage for driving the optical path deflecting element was 120 Hz, the vertical and horizontal phases of the two sheets were shifted by 90 degrees, and the drive timing was set so as to shift the pixels in four directions. By rewriting the subfield image to be displayed on the image display device at 240 Hz, a high-definition image in which the apparent number of pixels in the vertical and horizontal directions was multiplied by 4 could be displayed. The switching time of the optical path deflecting element was about 0.4 msec, and sufficient light utilization efficiency was obtained. Also, no flicker was observed.
[0088]
【The invention's effect】
According to the present invention, the opposing surface of the spacer that regulates the thickness of the liquid crystal layer is disposed in parallel to the direction of deflecting the optical path, and this spacer also serves as an electrode that applies an electric field to the liquid crystal layer in a planar direction. Thus, an optical deflecting element having a relatively simple configuration can be realized.
[0089]
A plurality of electrode lines are provided in a region (optical path region) where desired light is transmitted through the optical path deflecting element, and the voltage value applied to each electrode line is changed stepwise from the end side so that the entire region of the electrode line group is provided. By creating a macroscopically gradual potential gradient across the plane in the liquid crystal layer, it is possible to at least discretely obtain an effective portion in which the desired electric field strength is formed in the liquid crystal layer over the entire optical path region. Furthermore, by using only this effective portion, it is possible to relatively uniformly deflect an optical path having a large cross-sectional area.
[0090]
By having the electrode lines on both substrates, the potential distribution in the thickness direction of the liquid crystal layer becomes relatively uniform. That is, since the electric field strength in the thickness direction of the liquid crystal layer can be reduced, the director direction of the liquid crystal molecules when the electric field is applied becomes relatively uniform in the thickness direction of the liquid crystal layer, and efficient optical path deflection can be performed.
[0091]
If the distance between the electrode lines is wide, a portion with a low potential is generated near the middle between the lines, and an electric field in the opposite direction acts. However, the electrode lines are alternately arranged on the upper and lower substrates, and the voltage values are also alternated. By applying the voltage so as to change in the direction, the potential change in the surface direction in the liquid crystal layer becomes relatively uniform, and the generation of the reverse electric field can be reduced. In addition, by making the electrode a transparent material, the electrode line can also function as an optical path deflection region, and therefore, an optical path having a large cross-sectional area can be deflected relatively uniformly.
[0092]
In addition to the stepwise potential application by the electrode line in the optical path region, an auxiliary voltage is applied by the electrode also serving as a spacer member outside the optical path region to smooth the potential gradient in the plane direction in the liquid crystal layer. The optical path having a large cross-sectional area can be deflected relatively uniformly.
[0093]
When periodic potential gradient changes occur in the vicinity of the electrode line group, the amount of change in potential gradient in the plane direction in the liquid crystal layer is reduced by sandwiching the dielectric layer between the liquid crystal layer, and therefore uniform. An electric field strength distribution can be obtained.
[0094]
Since the dielectric layer also serves as the alignment film, the device manufacturing process can be simplified. In addition, by entering only light in the deflection direction of the optical path, that is, in the direction of polarization parallel to the tilt direction of the liquid crystal molecules when an electric field is applied, generation of light that is not deflected can be prevented, and reliable optical path deflection can be realized.
[0095]
Two optical path deflecting elements capable of deflecting in one direction are combined, the electric field application directions of both are rotated by 90 degrees, the polarization plane of the light emitted from the incident side optical path deflecting element is rotated by 90 degrees, By making the light incident on the second optical path deflecting element, the optical path can be reliably deflected in a two-dimensional direction.
[0096]
Since the optical path deflecting device using the change of the tilt direction of the ferroelectric liquid crystal molecules with respect to the substrate surface is used, high-speed optical path deflection is possible corresponding to the subfield image, and apparently high-definition image display is possible. It becomes possible. Further, since the switching time of the subfield image can be shortened by the high-speed response, there is an advantage that the temporal light use efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a first embodiment of the present invention.
FIG. 2 is a diagram schematically showing the alignment state of liquid crystal molecules.
FIG. 3 is a diagram for explaining the principle of operation of an optical deflection element according to the present invention.
FIG. 4 is a diagram for explaining a second embodiment of the present invention.
FIG. 5 is a diagram for explaining a third embodiment of the present invention.
FIG. 6 is a diagram for explaining a fourth embodiment of the present invention.
FIG. 7 is a diagram for explaining a fifth embodiment of the present invention.
FIG. 8 is a diagram for explaining a sixth embodiment of the present invention.
FIG. 9 is a diagram for explaining a seventh embodiment of the present invention.
FIG. 10 is a diagram for explaining a ninth embodiment of the present invention.
FIG. 11 is a diagram for explaining a tenth embodiment of the present invention.
FIG. 12 is a diagram illustrating a voltage distribution.
FIG. 13 is a diagram showing an electric field distribution of a 1 mm wide cell.
FIG. 14 is a diagram showing an electric field distribution of a 2 mm wide cell.
FIG. 15 is a diagram showing a potential distribution at a single-sided line electrode.
FIG. 16 is a diagram showing an electric field distribution at a single-sided line electrode.
FIG. 17 is a diagram showing an electric field distribution on a double-sided line electrode.
FIG. 18 is a diagram showing a potential distribution of double-sided alternating line electrodes.
FIG. 19 is a diagram showing an electric field distribution of double-sided alternating line electrodes.
FIG. 20 is a diagram illustrating a potential distribution also used as a spacer electrode.
FIG. 21 is a diagram showing an electric field distribution also used as a spacer electrode.
FIG. 22 is a diagram showing a potential distribution of a dielectric laminate type.
FIG. 23 is a diagram showing an electric field distribution of a dielectric laminate type.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical deflecting element, 2, 3 ... Substrate, 4 ... Alignment film, 5 ... Liquid crystal layer, 6a, 6b ... Electrode pair, 7 ... Power supply, 9 ... Electrode line, 10 ... Spacer, 11 ... Voltage application means, 12 ... Resistance, 13a, 13b ... Spacer and electrode pair, 14 ... Dielectric layer, 15 ... Wave plate, 16 ... Light deflection element, 21 ... Light source, 22 ... Diffuser plate, 23 ... Condenser lens, 24 ... Transmission type liquid crystal panel, 25 ... Projection lens, 26... Screen, 27. Light source drive unit, 28... Drive unit, 30.

Claims (10)

  A pair of transparent substrates, an alignment film for homeotropic alignment of liquid crystal molecules between both substrates, a liquid crystal layer for forming a chiral smectic C phase under no electric field, and at least regulating the thickness of the liquid crystal layer between the two substrates An optical path deflecting element having two or more spacers and at least two or more electrodes for generating an electric field in a direction substantially parallel to the liquid crystal layer, and a voltage applying means capable of switching the electric field direction between the electrodes And an optical deflection device that deflects the optical path of transmitted light in a direction substantially perpendicular to both the normal direction of the liquid crystal layer and the electric field direction by switching the direction in which the electric field is applied. An optical deflecting device, wherein the spacer is made of a conductive material, and a surface facing the spacer is an electrode arranged substantially parallel to a direction in which the optical path is deflected.   A pair of transparent substrates, an alignment film for homeotropic alignment of liquid crystal molecules between both substrates, a liquid crystal layer for forming a chiral smectic C phase under no electric field, and at least regulating the thickness of the liquid crystal layer between the two substrates An optical path deflecting element having two or more spacers and at least two or more electrodes for generating an electric field in a direction substantially parallel to the liquid crystal layer, and a voltage applying means capable of switching the electric field direction between the electrodes And deflecting the optical path of the transmitted light in a direction substantially orthogonal to both the normal direction of the liquid crystal layer and the electric field direction by switching the application direction of the electric field, wherein the optical path deflecting element comprises at least one of the optical path deflecting elements A plurality of electrode line groups arranged substantially parallel to a desired optical path shift direction in a region including the optical path on the substrate, wherein the voltage applying means applies to each electrode line at a certain time That the voltage value light deflecting device and sets the stage for a different value.   3. The optical path deflecting element according to claim 2, wherein the optical path deflecting element has a plurality of electrode line groups arranged substantially parallel to a desired optical path shift direction in a region including the optical paths on both substrates. Light deflection device.   4. The electrode line according to claim 3, wherein the electrode lines are made of a transparent electrode material, the positions of the transparent electrode lines on each substrate are alternately arranged as viewed from the optical path, and the voltage value applied to each transparent electrode line at a certain time is both An optical deflecting device which is set to different values alternately in steps between substrates.   5. The spacer according to claim 2, wherein the spacer is a pair of electrodes made of a conductive material provided outside a region of the optical path, and the electrode is interposed between the pair of electrodes with respect to the planar direction of the optical path deflecting element. A line group is provided, and the voltage applying means applies a voltage value greater than or equal to a maximum voltage value applied to the electrode line group to one of the electrode pairs at a certain time, and an electrode line to the other of the electrode pairs. An optical deflecting device that applies a voltage value equal to or lower than a minimum voltage value applied to the group.   6. The optical deflection according to claim 2, wherein a dielectric layer is provided on a substrate surface on which the electrode line group is formed, and an alignment film is provided between the dielectric layer and the liquid crystal layer. apparatus. The light deflecting device according to claim 6, wherein the dielectric layer is the alignment film . In any one of claims 1 to 7, the optical deflection apparatus characterized by having a polarization direction control means to match the polarization direction of the optical path of the polarization direction of the incident light to the optical path deflecting element. The polarization path rotating means for rotating the polarization plane of the outgoing light of the optical path deflecting element substantially at right angles, and the second optical path deflecting element that uses the outgoing light after the polarization plane rotation as incident light. the liquid crystal layer normal direction of the optical path deflecting element and said second optical path deflecting element is substantially coincident, optical deflecting device, wherein the electric field direction of Ryohikariro deflection elements arranged so as to be substantially orthogonal.   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 optical device for observing an image pattern displayed on the image display element And display driving means formed by a plurality of subfields obtained by temporally dividing the image field, and the light deflecting device according to any one of claims 1 to 9, which deflects an optical path of light emitted from each pixel, An image display characterized by multiplying the apparent number of pixels of the image display element by displaying an image pattern in which the display position is shifted according to the deflection state of the optical path for each subfield. apparatus.

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