JP2005309100A - Optical element, optical deflection element, optical deflection device and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which can be used as a functional element other than an optical deflection element, to provide the optical deflection element and an optical deflection device capable of being inexpensively constituted as compared with conventional one and to provide an image display apparatus wherein reduction of resolution of an optical system is suppressed and an image of high definition can be obtained using the optical deflection element and the optical deflection device. <P>SOLUTION: The optical element 10 wherein a pair of substrates 21 and 22 comprising the substrate 22 comprising a uniaxial crystal are formed and a liquid crystal layer 20 is interposed between the pair of substrates 21 and 22 is characterized in that the uniaxial crystal has an optical axis in a direction other than the normal direction of the substrates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element, an optical deflection element, and an optical deflection device that change the traveling direction of light by an electrical signal, and to an image display apparatus using the optical deflection element and the optical deflection device.

Conventionally, as a deflecting element and an optical deflecting element that change the traveling direction of light according to an electric signal, KH ₂ PO ₄ (KDP), NH ₄ H ₂ PO ₄ (ADP), LiNbO ₃ , LiTaO ₃ , GaAs, CdTe, etc. Materials with large primary electro-optic effect (Pockels effect), electro-optic devices using materials with large secondary electro-optic effect such as KTN, SrTiO ₃ , CS ₂ , nitrobenzene, glass, silica, TeO _2, etc. Acousto-optic devices using materials are known.

  In general, electro-optic devices change the refractive index by applying a high voltage to modulate the optical path or light intensity, and acousto-optic devices perform optical diffraction by applying ultrasonic waves and inducing standing waves. Let me control. However, in order to obtain a sufficiently large amount of light deflection by these methods, it is necessary to make the optical path length long, but the use is limited because the material is expensive.

  On the other hand, for example, Patent Documents 1 and 2 propose optical members that can turn the direction of transmitted light using a liquid crystal material.

  In Patent Document 1, in a projection display device that enlarges and projects an image displayed on a display element onto a screen by a projection optical system, an optical member capable of turning the direction of transmitted light in the middle of an optical path from the display element to the screen Means for shifting a projection image having at least one transparent element having a birefringence effect and at least one transparent element having a birefringence effect, and effectively reducing the aperture ratio of the display element. A projection display device comprising: means for discretely projecting a projection area on the screen.

  In Patent Document 1, a projected image having at least one optical member (polarization direction control liquid crystal panel) capable of rotating the polarization direction and at least one transparent element (quartz plate) having a birefringence effect. Pixel shift (described later) is performed by shift means (pixel shift means).

  In Patent Document 2, the resolution of a display image is apparently improved without increasing the number of pixels of an image display device such as an LCD, and each of a plurality of pixels arranged in the vertical and horizontal directions is displayed. An optical member that changes the optical path for each field is arranged between the image display device that emits light according to the pixel pattern and displays an image, and the observer or the screen, and changes the optical path for each field. The display pixel pattern in a state where the display position is shifted is displayed on the image display device, and the portions having different refractive indexes are alternately optical paths between the image display device and the observer or the screen for each field of the image information. The optical path is changed so that it appears inside.

In Patent Document 2, 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 as means for changing the optical path. In addition to the method of combining elements, a method of switching the optical path by displacing (translating, tilting) a lens, a reflecting plate, a birefringent plate, etc. by a voice coil, a piezoelectric element or the like is proposed.
Japanese Patent No. 2939826 JP-A-6-324320

Since the optical crystal used in the conventional birefringent element is provided separately from the optical member that can turn the polarization direction of the transmitted light, it has the following problems.
(1) Since there are a large number of interfaces, the wavefront aberration tends to increase and the optical characteristics are deteriorated.
(2) The manufacturing process increases and the manufacturing cost increases.
(3) The element becomes larger. When incorporated in a projection optical system such as a projector, the back focus length becomes long, so that the optical system becomes large.

  Conventionally, in order to be able to select a plurality of deflection positions, an optical deflection device in which a plurality of optical deflection elements are combined has been provided. The defect becomes more prominent.

  On the other hand, Patent Document 1 discloses a configuration of a liquid crystal panel for controlling a polarization direction that uses two glass substrates and sandwiches a liquid crystal in Example 1, but there are many interfaces and elements. Problems associated with the increase in size are not considered.

  Further, the method using an optical crystal as the birefringent element disclosed in Patent Document 2 has the same problem as that of Patent Document 1, and the method for displacing the birefringent plate or the like has a configuration for driving the optical member. There was a problem that it became complicated and cost increased.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an optical element that can be diverted to a functional element other than an optical deflection element, and is extremely inexpensive compared to the prior art. The present invention provides an optical deflecting element and an optical deflecting device that can be configured to provide an image display device that uses the optical deflecting element and the optical deflecting device to suppress a decrease in the resolution of the optical system and obtain a high-definition image. There is to do.

  As a result of various studies to achieve the above object, the present inventor made at least one of a pair of substrates in an optical element or the like a uniaxial crystal that deflects the traveling direction of light, etc. The present inventors have found that the above problems can be achieved and have come to the present invention.

  That is, the optical element of the present invention is an optical element in which a pair of substrates including a substrate made of a uniaxial crystal is formed, and a liquid crystal layer is sandwiched between the pair of substrates. It has an optical axis in a direction other than the normal direction of the substrate.

  The optical deflection element of the present invention is an optical deflection element in which a pair of substrates is formed by a substrate made of an isotropic material and a substrate made of a uniaxial crystal, and a liquid crystal layer is sandwiched between the pair of substrates. The uniaxial crystal has an optical axis in a direction other than the normal direction of the substrate.

  The substrate may be disposed in the light incident direction, and the birefringent element may be disposed in the light emitting direction.

  The optical deflection device of the present invention is an optical deflection device in which a pair of substrates is formed, and two or more deflection elements each having a liquid crystal layer sandwiched between the pair of substrates are overlapped. Is composed of a substrate made of an isotropic material and / or a substrate made of a uniaxial crystal.

  Another optical deflecting element of the present invention is an optical deflecting device in which a pair of substrates is formed by a substrate made of an isotropic material and a substrate made of a uniaxial crystal, and a plurality of liquid crystal layers are sandwiched between the pair of substrates. An element, wherein the substrate or the uniaxial crystal is sandwiched between the plurality of liquid crystal layers, and the uniaxial crystal has an optical axis in a direction other than a normal direction of the substrate. To do.

  The uniaxial crystal can be configured to be quartz.

  The image display device of the present invention includes an image display element in which a plurality of pixels capable of controlling the light emission intensity according to image information are two-dimensionally arranged, a light source that illuminates the image display element, and a display on the image display element An optical member for observing the image pattern, and a light path between the image display element and the optical member is deflected for each of a plurality of subfields obtained by temporally dividing an image field for displaying the image pattern. A state in which the display position is shifted in accordance with the deflection of the optical path for each of the subfields, the optical deflection element according to claim 3 or 5 and the optical deflection means selected from the group of optical deflection devices according to claim 4. By displaying this image pattern, the apparent number of pixels of the image display element is multiplied and displayed.

  Another image display device of the present invention includes an image display element in which a plurality of pixels capable of controlling the light emission intensity according to image information are two-dimensionally arranged, a light source that illuminates the image display element, and a light source from the light source. A color arrangement unit that colors light corresponding to the pixels of the image display element, an optical member for observing the image pattern displayed on the image display element, and a plurality of temporally divided image fields that display the image pattern 6. An optical deflection element selected from the group of optical deflection elements according to claim 2, and an optical deflection device according to claim 4, which deflects an optical path between the image display element and the optical member for each subfield of And displaying an image pattern in a state where the display position is shifted in accordance with the deflection of the optical path for each subfield, thereby multiplying and displaying the apparent number of pixels of the image display element. And it features.

  The optical element of the present invention has an advantage that it can be diverted to a functional element other than the light deflection element.

  The optical deflecting element and the optical deflecting device of the present invention have an advantage that they can be configured at a very low cost as compared with the prior art.

  The optical deflecting element and the optical deflecting device of the present invention are excellent in heat resistance and chemical resistance required in the liquid crystal cell formation process because the uniaxial crystal is quartz. This is possible, and since the refractive index is close to that of general commercial glass, when multiple optical deflecting elements are bonded with an optical adhesive having the same refractive index as these, the effect on interface aberrations is reduced. Can do.

  The image display apparatus of the present invention has advantages that not only the back focus can be shortened, but also that the apparatus can be made compact and can be configured at low cost.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  Before describing the present invention, first, the configuration of a deflecting element using a conventional birefringent element will be described. A schematic diagram of a conventional deflection element 1 is shown in FIG. An optical member 2 that can change the polarization direction of incident linearly polarized light with time, and a birefringent element 3 that changes the traveling direction of light emitted from the optical member 2 according to the polarization direction. As the optical member 2, a liquid crystal material is preferably used, and a ferroelectric liquid crystal is preferable for applications that require a high-speed response.

  By selecting a material satisfying the relationship of dn · h = λ / 2 (λ is a predetermined wavelength in visible light) between the refractive index difference dn of ordinary light and extraordinary light and the thickness h, a straight line is obtained. The polarized light can be emitted by changing the polarization direction by a predetermined angle.

For the birefringent element 3, an optical crystal material having birefringence is used, and a uniaxial optical crystal is generally used. That is, a material having a large primary electro-optic effect (Pockels effect) such as KH ₂ PO ₄ (KDP), NH ₄ H ₂ PO ₄ (ADP), LiNbO ₃ , LiTaO ₃ , GaAs, CdTe, KTN, SrTiO ₃ , Materials having a large secondary electro-optic effect such as CS ₂ and nitrobenzene, and materials such as TeO ₂ are used.

  The operation of a deflection element using a conventional birefringent element will be described. Incident light is set in advance as linearly polarized light, and its polarization direction is determined from the relationship with the axial direction of the optical crystal of the birefringent element. Specifically, as shown in FIG. 10, the uniaxial optical crystal described above is used as the birefringent element 3 and the crystal axes are (X, Y, Z) = (1, 0, − In the case of 1), the polarization direction of the incident light (the vibration plane of the electric field vector) is selected so as to coincide with the XY plane or the XZ plane.

  Hereinafter, a case where the polarization direction of incident light is in the XY plane will be described. When the light passes through the deflecting element 2, the direction of polarization of incident light can be selected at 0 ° or 90 ° in terms of time. For example, the ferroelectric liquid crystal 5 is used as a deflecting element, and the molecular long axis direction is a direction at a tilt angle of 45 ° from the polarization direction of incident light when a voltage + V is applied, that is, (0, 1, 1) direction or (0 , 1, -1) direction (FIG. 10B), and when a voltage of -V is applied, the (0, 1, 0) direction parallel to the polarization direction of incident light or the vertical (0, 0, 1) direction ( The orientation direction of the liquid crystal may be selected as shown in FIG. This alignment direction can be controlled by the direction of rubbing treatment in the alignment film 6 provided on the liquid crystal side interface of the substrate 4.

  When the polarization direction of light emitted from the optical member 2 is 0 °, that is, when the polarization direction of linearly polarized light is incident on the birefringent element 3 while maintaining the XY plane, the polarization direction is perpendicular to the optical crystal axis. Therefore, the light does not shake as ordinary light and goes straight without receiving rotation. This light is emitted to the position indicated as the first outgoing light in FIG.

  On the other hand, when the optical member 2 receives a 90 ° rotation, the linearly polarized light rotates its polarization direction to the XZ plane and enters the birefringent element 3. The principle of 90 ° rotation is as described above. In this case, since the polarization direction (Z-axis direction) is not perpendicular to the optical crystal axis, the light does not behave as abnormal light and travels in a predetermined direction (inclined downward in FIG. 10). This light is emitted as shown as the second outgoing light in the figure.

FIG. 11 shows the light shift amount calculated when LiNbO ₃ is used as the birefringent element 3. Crystal axis is identical to that shown in FIG. 10, the refractive index is obtained when the wavelength _{633nm (n o = 2.286, n} e = 2.200) was used. To obtain 5.0 μm ± 0.2 μm as the optical path shift amount, the crystal thickness is 130.5 μm ± 5.2 μm.

  Next, the optical element (light deflection element) and the light deflection device of the present invention will be described. FIG. 1 shows a schematic cross-sectional view of one embodiment of the optical element (light deflection element) of the present invention. In FIG. 1, an optical element (light deflecting element) 10 is isotropic with a substrate 21 made of an isotropic material arranged in the light incident direction, a substrate 22 made of a uniaxial crystal arranged in the light emitting direction. A liquid crystal layer 20 sandwiched between a substrate 21 made of a conductive material and a substrate 22 made of uniaxial crystal. The substrate 22 made of uniaxial crystal has an optical axis in a direction other than the normal direction of the substrate. Examples of the isotropic material include plastic materials (polycarbonate, polymethyl methacrylate (PMMA), etc.), glass materials, and the like, but the same material as the optical member 2 shown in FIG. 10 described above is used. Is also possible. As the liquid crystal layer 20, a liquid crystal similar to the liquid crystal having the properties shown in FIG. 10 can be used, and a ferroelectric liquid crystal is preferable for applications requiring a high-speed response. Further, as the uniaxial crystal used for the substrate 22, the same uniaxial optical crystal as described above can be used within a range satisfying the conditions described later. When FIG. 1 and FIG. 10 are compared, there is an advantage that the number of components is small and the same function can be provided.

  The uniaxial crystal used in the present invention needs to be stable not only in optical performance but also in a liquid crystal cell forming process as compared with the conventional example. In other words, it is necessary to have excellent heat resistance and chemical resistance and excellent physical strength. For example, in order to uniformly align liquid crystal molecules, an alignment film is generally formed on a substrate, but isopropyl alcohol (IPA) or N-methyl-2-pyrrolidone (NMP) is used to apply this alignment film. Organic solvents such as these are often used as diluents, and chemical resistance to these is required. When tin-added indium oxide (ITO) is formed as a transparent electrode by sputtering, the substrate is often heated to about 300 ° C., and the substrate itself is required to have heat resistance.

The C-axis direction and the thickness of the uniaxial crystal are determined by, for example, the calculation example shown in FIG. 11 so that the amount of light deflection becomes a predetermined value. The material cost increases as the thickness increases, but conversely, if it is thin, the strength as a substrate is lowered and the substrate is easily damaged, and it is difficult to ensure surface smoothness due to the curvature and the wavefront aberration is easily reduced. Furthermore, the thing with a small refractive index difference with the adjacent liquid crystal or glass is good. From these properties, the uniaxial crystal used in the present invention is preferably quartz (for example, α-SiO ₂ ).

  A schematic cross-sectional view of one embodiment of the optical deflection device of the present invention is shown in FIG. In FIG. 2, the optical deflection device 12 has a configuration in which a front deflection element 12a in the light incident direction and a rear deflection element 12b in the light emission direction are overlapped. In the front deflecting element 12a, after selecting whether or not the light is deflected, the rear deflecting element 12b further selects the deflection, so that a total of four kinds of outgoing light can be obtained. The front deflection element 12a and the rear deflection element 12b may have the same configuration or may be different. In the case where the structures are exactly the same, the second outgoing light and the third outgoing light are in the same position in FIG. 2, and the light deflection at a total of three positions can be controlled. Further, by changing the thickness of the substrate 22a made of a uniaxial crystal in the front deflection element 12a and the thickness of the substrate 22b made of a rear uniaxial crystal in the rear deflection element 12b, while using the same kind of optical crystal, Various light deflection positions can be obtained, which is convenient.

  The front deflection element 12a and the rear deflection element 12b do not form an air interface and are bonded with a transparent optical adhesive whose refractive index is close to that of the front uniaxial crystal substrate 22a and the rear uniaxial crystal substrate 22b. Is preferable for improving the wavefront aberration. In addition, although the optical axis direction of the substrate made of uniaxial crystal in FIG. 2 is parallel, it may be arranged with an angle depending on the polarization direction, and in that case, the angle is formed by the rear liquid crystal layer 20b. It is preferable to employ a twisted nematic liquid crystal or the like so that the polarization direction can be changed according to the above.

  From the structure shown in FIG. 2, the rear substrate 21b made of isotropic material is omitted, and a plurality of liquid crystal layers are provided between the front isotropic material substrate 21a and the rear uniaxial crystal substrate 22b. Even with the simplified arrangement, it is possible to have the same function as the optical deflection device 12 shown in FIG. One embodiment of the optical deflection element having such a structure is shown in FIGS. In the light deflection element 11 of FIG. 6, two liquid crystal layers 20a and 20b are sandwiched between a substrate 21a made of a front isotropic material and a substrate 22b made of a rear uniaxial crystal, and the front liquid crystal layer 20a and The substrate 22a made of uniaxial crystal is sandwiched between the rear liquid crystal layer 20b, and the light deflection element 11 in FIG. 7 is made of the front substrate 21a made of isotropic material and the rear uniaxial crystal. Two liquid crystal layers 20a and 20b are sandwiched between the substrate 22b, and a substrate 21a made of an isotropic material is sandwiched between the front liquid crystal layer 20a and the rear liquid crystal layer 20b. As in these examples, in an optical element having a plurality of liquid crystal layers sandwiched between a pair of substrates, it is further simplified by adopting a uniaxial crystal having an optical axis in a direction other than the substrate normal direction. An optical deflecting element that can be deflected to a plurality of positions in the configuration can be obtained.

  A schematic cross-sectional view of another embodiment of the optical deflection device of the present invention is shown in FIG. In FIG. 3, in the optical deflection device 12, a front deflection element 12a is composed of a pair of substrates 21a and 21b made of isotropic material, and a rear deflection element 12b is a pair of substrates made of a uniaxial crystal 22a. , 22b. A substrate 21a made of a front isotropic material, a front liquid crystal layer 20a, a substrate 21b made of a rear isotropic material, and a substrate 22a made of a front uniaxial crystal are the same as the optical member 2 in the conventional example shown in FIG. It is the same composition. The light emitted from the front deflection element 12a is first selected by the substrate 22a made of a uniaxial crystal in front of the rear deflection element 12b according to the polarization direction, and further changed in polarization direction by the rear liquid crystal layer 20b. After that, the light is further deflected by the rear substrate 22b made of uniaxial crystal. A total of four types of outgoing light can be obtained as in the case of FIG.

  A schematic cross-sectional view of another embodiment of the optical deflection device of the present invention is shown in FIG. The optical deflection device 12 shown in FIG. 4A is obtained by arranging two sets of the deflection elements 12a shown in FIG. FIG. 4B shows an outgoing light position when the optical deflection device of FIG. 4A is observed from the + X direction to the −X direction. A total of four types of outgoing light can be obtained two-dimensionally.

  The image display apparatus of the present invention will be described. Here, the pixel shift element is an image display element in which a plurality of pixels that can control light according to image information are two-dimensionally arranged, a light source that illuminates the image display element, and an image pattern displayed on the image display element And an optical deflector for deflecting the optical path between the image display element and the optical member for each of a plurality of subfields obtained by temporally dividing the image field. It is an optical deflecting means in an image display device that displays an image pattern in which the display position is shifted in accordance with the deflection, thereby increasing the apparent number of pixels of the image display element. Therefore, basically, the above-described optical deflection element or optical deflection device can be applied.

  A schematic diagram of one embodiment of the image display device of the present invention is shown in FIG. In FIG. 8, reference numeral 42 denotes a light source in which LED lamps are arranged in a two-dimensional array. In the optical path of light emitted from the light source 42 toward the screen 43, a diffusion plate 44, a condenser lens 45, a polarized beam splitter ( PBS) 52, a reflective liquid crystal display element (LCOS: Liquid Crystal On Silicon) 46 as an image display element, and a projection lens 47 as an optical member for observing image light that has passed through the PBS after being reflected by the LCOS 46. It is installed. Reference numeral 48 denotes a light source drive unit for the light source 42, and 49 denotes a liquid crystal drive unit for the LCOS 46.

  Here, on the optical path between the LCOS 46 and the projection lens 47, an optical deflecting means 50 functioning as a pixel shift element is interposed and connected to the drive unit 51. As such an optical deflection means 50, the optical deflection element / optical deflection device described above is used.

  The illumination light that is controlled by the light source drive unit 48 and emitted from the light source 42 becomes uniform illumination light by the diffuser plate 44, and is controlled by the condenser lens 45 in synchronization with the illumination light source by the liquid crystal drive unit 49 to control the LCOS 46. Use critical lighting. The illumination light that has been spatially modulated by the LCOS 46 is magnified by the projection lens 47 as image light and projected onto the screen 43. The shift amount in the light deflector is set to ½ of the pixel pitch because image multiplication is performed twice in the pixel arrangement direction. By correcting the image signal for driving the liquid crystal panel according to the shift amount by the shift amount, an apparently high-definition image can be displayed.

  The light deflection means 50 is disposed between the PBS 52 and the projection lens 47 as shown in FIG. 8, but when the thickness of the light deflection means increases, the back focus length required for the projection lens 47 (the LCOS side end of the projection lens) is increased. The optical path length from the LCOS to the LCOS) becomes long, and the size of the projection lens becomes large.

  The use of the thin optical deflection element / optical deflection device of the present invention is useful because the back focus can be shortened as compared with the prior art.

  A schematic diagram of another embodiment of the image display device of the present invention is shown in FIG. In FIG. 9, reference numeral 42 denotes a white light source such as a high-pressure mercury lamp. In the traveling direction of light emitted from the light source 42 toward the screen 43, a condenser lens 45, a transmissive liquid crystal panel 53 as an image display element, an image pattern A projection lens 47 as an optical member for observing the light is disposed in order. Reference numeral 48 denotes a light source drive unit for the light source 42, and 49 denotes a liquid crystal drive unit for the transmissive liquid crystal panel 53. Between the lamp and the condenser lens, a polarization conversion element for improving light utilization efficiency, a fly-eye lens for uniformizing the amount of illumination light, and the like can be provided.

  Each pixel in the image display element is periodically provided with red (R), green (G), and blue (B) color filters for color display. Instead of providing a color filter, the illumination light incident on the image display element is separated into red (R), green (G), and blue (B) colors by a hologram element or the like, and the corresponding pixels are illuminated with the respective colors. May be.

  On the optical path between the transmissive liquid crystal panel 53 and the projection lens 47, an optical deflecting means 50 functioning as a pixel shift element is interposed and connected to the drive unit 51. As such an optical deflection means 50, the optical deflection element / optical deflection device as described above is used, and an optical deflection device having a structure shown in FIG. 8 is particularly suitable. The operation of the optical deflection device will be described later.

  Illumination light emitted from the light source 42 critically illuminates the transmissive liquid crystal panel 53 by the condenser lens 45. The illumination light spatially modulated by the transmissive liquid crystal panel 53 is incident on the light deflecting unit 50 as image light. The light deflecting unit 50 shifts the image light by an arbitrary distance in the pixel arrangement direction. This light is magnified by the projection lens 47 and projected onto the screen 43.

  Here, a subfield is prepared by temporally dividing the image field into three, and the light deflection means 50 causes the optical path deflection of 0, 1, 2 pixels for each subfield. This makes it possible to display an image of each RGB pixel adjacently arranged in the transmissive liquid crystal panel as an image pattern at a certain pixel position on the screen. It is observed that RGB composite colors are displayed from the pixels. FIG. 5 schematically shows this optical path. (R), (G), and (B) shown on the incident light side correspond to light emitted from the three pixels color-coded by the color filter. The emitted light is one pixel position on the screen.

  Since the light deflection element or the light deflection device of each embodiment of the present invention described above is used as the light deflection means 50, the same effect as the image display apparatus shown in FIG. 8 is obtained.

(Example 1)
A glass substrate (1.1 mm thickness) made of BK7 and a single crystal quartz substrate (1.12 mm thickness) cut by tilting the C axis from the normal direction to the long side by 45 ° were prepared as a pair of substrates. CS1029 (Chisso Corporation) was prepared as the liquid crystal material, and AL3046-R31 (JSR member) was prepared as the alignment agent. As the spacer particles for ensuring the gap of the liquid crystal layer, those having a diameter of 1.7 μm were prepared so that incident linearly polarized light having a wavelength of 544 nm was emitted as linearly polarized light while maintaining a predetermined angle based on the difference in refractive index of the liquid crystal.

  After cleaning each substrate, ITO was formed on the entire surface by sputtering. Thereafter, an alignment agent was spin-coated, prebaked on a hot plate, and then heated and sintered in an oven at 120 ° C. for 1 hour. The obtained alignment film was rubbed. The rubbing direction was set to be parallel between the substrates on both sides. After the rubbing treatment, spacer particles were sprayed on the glass substrate side, and both substrates were bonded. Thereafter, the temperature was maintained at 90 ° C. on a hot plate, and liquid crystal was injected between the substrates by a capillary method to form a liquid crystal cell. This liquid crystal cell has the same structure as the optical element (light deflecting element) shown in FIG.

  The obtained optical element (light deflecting element) 1 was visually transparent. Two polarizers were prepared, and an optical element (light deflection element) 1 was inserted in parallel between the polarizers in a crossed Nicol arrangement. A voltage of +5 V was applied between the ITO of the optical element (light deflecting element) 1 and the optical element (light deflecting element) 1 was rotated in the azimuth direction while maintaining a parallel state to obtain a position where incident light was shielded. (This position is called the reference position with respect to the polarization direction of the incident linearly polarized light). In this state, bright light was obtained when a voltage of -5 V was applied across the ITO. When this voltage state was maintained and the optical element (light deflecting element) 1 was rotated, incident light was shielded at a position rotated about 90 °. As a result, it was confirmed that the incident voltage was emitted while maintaining the linearly polarized light by switching the polarization direction by 90 ° by switching the polarity with the applied voltage of 5V.

  An optical microscope was prepared, the transmitted illumination was linearly polarized with a polarizer, and a mask chart in which squares were periodically formed with a pitch of 20 μm and a side of 5 μm was observed. The optical element sample was inserted between the mask chart and the objective lens, and the reference position was matched with the linearly polarized light. By applying a voltage of ± 5 V to the optical element, it was confirmed that the square was deflected by about 7 μm, and it was confirmed that this optical element (light deflection element) 1 functions normally as a light deflection element. .

(Comparative Example 1)
Instead of the single crystal quartz substrate of Example 1, a liquid crystal cell was formed in the same process using a glass substrate (1.1 mm thick) made of BK7, and an optical member R1 serving as a comparative example was obtained. Single crystal quartz used in Example 1 was bonded to this liquid crystal cell with an optical adhesive. This element is a deflection element according to the prior art shown in FIG. 10, and this is used as a comparative example R1.

  The same observation as that of the optical element (light deflection element) 1 of Example 1 was performed on the comparative example R1. In Comparative Example R1, light deflection similar to that of the optical element (light deflection element) 1 was confirmed by microscopic observation, but the shape of the square pattern of the mask chart was blurred compared to the optical element (light deflection element) 1. Was recognized. This is presumably because the number of interfaces increased as compared with the optical element (light deflecting element) 1 and the wavefront aberration increased. From this, it was confirmed that the optical element (optical deflection element) of the present invention was superior in optical performance as compared with the conventional deflection element.

(Example 2)
In the image display apparatus shown in FIG. 8, the optical element (light deflection element) 1 is inserted as a light deflection means so as to coincide with the polarization direction of the image light from the image display element. When the image as described in the description was displayed and the optical element was made to function, the pixel shift was confirmed by switching the applied voltage at ± 5 V, and a high-resolution image twice that before the installation of the light deflection means was obtained.

(Example 3)
Two sets of optical elements (light deflection elements) 1 obtained in Example 1 were prepared. The optical deflection devices 3 belonging to the present invention were obtained by bonding the reference positions so as to be orthogonal to each other. This structure is the same as the optical deflection device 12 shown in FIG. It was confirmed that the first to fourth emission lights could be obtained by selecting the applied voltage polarities of the two sets of liquid crystals. When the light deflection device 3 was mounted on the image display apparatus shown in FIG. 8 and driven, a pixel shift was confirmed, and a four times higher resolution image than before installation of the light deflection means was obtained.

Example 4
Two sets of optical elements (light deflection elements) 1 obtained in Example 1 were prepared. However, the thickness of the single crystal quartz substrate was 2.24 mm. These samples were bonded in an arrangement in which the respective reference positions were parallel to obtain an optical deflection device belonging to the present invention. This structure is the same as the optical deflection device 12 shown in FIG. By selecting the applied voltage polarities of the two sets of liquid crystals, it was confirmed that the emitted light was obtained at the same position with respect to the first to fourth incident lights as shown in FIG. When the light deflection device 4 was mounted on the image display apparatus shown in FIG. 8 and driven, a good color image was confirmed.

It is a schematic sectional drawing which shows the structure of one embodiment of the optical element (light deflection | deviation element) of this invention. It is a schematic sectional drawing which shows the structure of one embodiment of the optical deflection | deviation device of this invention. It is a schematic sectional drawing which shows the structure of the other embodiment of the optical deflection | deviation device of this invention. (A) It is a schematic sectional drawing which shows the structure of the other embodiment of the optical deflection | deviation device of this invention. (B) It is a figure for demonstrating the position of the emitted light of (a). It is a schematic sectional drawing which shows the structure of the other embodiment of the optical deflection | deviation device of this invention. It is a schematic sectional drawing which shows the structure of one embodiment of the optical deflection | deviation element of this invention. It is a schematic sectional drawing which shows the structure of the other embodiment of the optical deflection | deviation element of this invention. It is the schematic which shows one embodiment of the image display apparatus of this invention. It is the schematic which shows the other embodiment of the image display apparatus of this invention. (A) It is a schematic sectional drawing which shows the structure of an example of the conventional deflection | deviation element. (B) It is a figure which shows the mode of the orientation of the liquid crystal in case the voltage + V is applied to the conventional deflection | deviation element. (C) It is a figure which shows the mode of the orientation of the liquid crystal in case the voltage -V is applied to the conventional deflection | deviation element. Is a graph showing the relationship between crystal thickness and the light deflection amount of LiNbO ₃ in the case of using a LiNbO ₃ as the birefringent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conventional deflection element 2 Optical member 3 Birefringence element 4 Substrate 5 Ferroelectric liquid crystal 6 Alignment film 10 Optical element (optical deflection element)
DESCRIPTION OF SYMBOLS 11 Optical deflection element 12 Optical deflection device 12a Front deflection element 12b Rear deflection element 20 Liquid crystal layer 20a Front liquid crystal layer 20b Rear liquid crystal layer 21 Substrate made of isotropic material 21a Substrate made of isotropic material 21b Back substrate made of isotropic material 22 Substrate made of uniaxial crystal 22a Front substrate made of uniaxial crystal 22b Substrate made of rear uniaxial crystal 42 Light source 43 Screen 44 Diffusion plate 45 Condenser lens 46 Reflective liquid crystal display element 47 Projection lens 48 Light source drive unit 49 Liquid crystal drive unit 50 Optical deflecting means 51 Drive unit 52 Polarized beam splitter 53 Transmission type liquid crystal panel

Claims (9)

An optical element formed by forming a pair of substrates including a substrate made of uniaxial crystal and sandwiching a liquid crystal layer between the pair of substrates,
The uniaxial crystal has an optical axis in a direction other than the normal direction of the substrate. An optical deflection element in which a pair of substrates is formed by a substrate made of an isotropic material and a substrate made of a uniaxial crystal, and a liquid crystal layer is sandwiched between the pair of substrates,
The uniaxial crystal has an optical axis in a direction other than the normal direction of the substrate.   The light deflection element according to claim 2, wherein the substrate is disposed in a light incident direction, and the uniaxial crystal is disposed in a light emitting direction. An optical deflection device comprising a pair of substrates and two or more deflection elements formed by sandwiching a liquid crystal layer between the pair of substrates,
The pair of substrates is constituted by a substrate made of an isotropic material and / or a substrate made of a uniaxial crystal. An optical deflection element in which a pair of substrates is formed by a substrate made of an isotropic material and a substrate made of a uniaxial crystal, and a plurality of liquid crystal layers are sandwiched between the pair of substrates,
The optical deflection element, wherein the substrate or the uniaxial crystal is sandwiched between the plurality of liquid crystal layers, and the uniaxial crystal has an optical axis in a direction other than a normal direction of the substrate.   The optical deflection element according to claim 2, 3 or 5, wherein the uniaxial crystal is quartz.   The optical deflection device according to claim 4, wherein the uniaxial crystal is quartz. An image display element in which a plurality of pixels capable of controlling the light emission intensity according to image information are two-dimensionally arranged, a light source that illuminates the image display element, and an image pattern displayed on the image display element 6. The optical deflection according to claim 2, 3 or 5, wherein the optical path between the image display element and the optical member is deflected for each of the optical member and a plurality of subfields obtained by temporally dividing the image field for displaying the image pattern. An optical deflection means selected from the group of optical deflection devices according to claim 4,
An image characterized by displaying an image pattern whose display position is shifted in accordance with the deflection of the optical path for each subfield, thereby multiplying the apparent number of pixels of the image display element. Display device. An image display element in which a plurality of pixels whose light emission intensity can be controlled according to image information is arranged two-dimensionally, a light source that illuminates the image display element, and light from the light source corresponds to the pixel of the image display element Color arrangement means for color arrangement, an optical member for observing the image pattern displayed on the image display element, and an image display element and an optical element for each of a plurality of subfields obtained by temporally dividing an image field for displaying the image pattern An optical deflection element according to claim 2, 3 or 5, which deflects an optical path between members, and an optical deflection means selected from the group of optical deflection devices according to claim 4,
An image characterized by displaying an image pattern whose display position is shifted in accordance with the deflection of the optical path for each subfield, thereby multiplying the apparent number of pixels of the image display element. Display device.

Images