JP4438497B2 - Optical deflection element - Google Patents

Description

The present invention relates to an optical deflection element for changing the direction of light by an electrical signal, and more particularly to a liquid crystal prism using an electro-optical effect of liquid crystal. The present invention is applied to electronic display devices such as projection displays and head mounted displays, optical writing devices for laser beam printers, laser radar systems, and the like.

  For example, the following technique is disclosed in “Two-dimensional phased array light beam directing device” disclosed in Patent Document 1. That is, the optical beam deflector includes a first window having a common electrode, a second window having a plurality of electrodes in the form of electrically separated parallel stripes, and between the first and second windows. A liquid crystal cell element including a liquid crystal molecular layer, the plurality of stripe electrodes, and a plurality of control signals are individually coupled between the common electrodes to cause a selectable local change in refractive index in the liquid crystal layer. Means (see FIG. 9).

  Further, for example, the following technique is shown in “Electrode structure for efficient wavefront modulation of liquid crystal” disclosed in Patent Document 2. That is, in an apparatus for wavefront modulating an optical beam, a first window having an optically transparent common electrode, a second window having a number of electrically conductive parallel striped transparent conductive electrodes, and a first window And an optical element comprising a liquid crystal molecular layer provided in the middle of the second window, wherein the optical device is positioned such that the optical beam is incident on the first window and reflected or transmitted by the second window; By providing means for individually applying control signals to the outer electrode of each cell, a voltage gradient of linear information is generated along the junction electrode and through the cell region, depending on the linear or non-linear part of the electro-optical properties of the LC. An apparatus for wavefront modulating an optical beam, characterized in that the liquid crystal layer is configured to cause a local change in refractive index (see FIG. 10).

Further, for example, “Liquid Crystal Light Modulator and Driving Method” of Patent Document 3 discloses the following technology. That is, in a light modulation device using liquid crystal, a first substrate having a composite electrode obtained by electrically bundling a plurality of conductive electrodes in a parallel stripe shape with one or a plurality of connecting conductive stripe electrodes, and a common electrode And an optical element including a liquid crystal molecular layer sandwiched between the first substrate and the second substrate, and the connection stripe electrode has a signal electrode for applying a control signal at a predetermined interval. Then, by applying a predetermined voltage to each signal electrode, a linear potential gradient is generated in the conductive stripe electrode for connection between each signal electrode, and thereby the liquid crystal is generated by the curve modulation region of the electro-optic characteristic of the homogeneously aligned liquid crystal. It is a liquid crystal light modulation device configured to cause refractive index modulation in a molecular layer (see FIG. 11).
Japanese Patent No. 3267650 JP-A-10-221703 JP 2000-214429 A

  In the above known technique, the voltage value applied to each stripe electrode is changed stepwise as shown in FIGS. 12A and 12B, and the electric field strength between the opposing common electrodes is changed stepwise. ing. Since the refractive index of the liquid crystal layer with respect to the incident linear deflection changes according to the electric field strength, the refractive index distribution in the element also becomes stepwise as shown in FIG. Since this type of light deflection element deflects light by the prism effect or lens effect due to the refractive index distribution in the liquid crystal layer, the graded refractive index distribution causes the generation of aberrations.

  Reducing the width and pitch of the stripe electrodes to increase the number and applying a voltage at a fine level can provide a relatively continuous refractive index distribution. However, the increase in the number of stripe electrodes increases the complexity and diffraction of the substrate. Problems such as light generation occur.

The invention, and purpose that the number of stripe electrodes be relatively small can continuously control the refractive index distribution of the liquid crystal layer to obtain a light deflection element that can reduce the occurrence of generation or liquid crystal alignment defects aberrations To do.

According to the first aspect of the present invention, a first substrate having a plurality of transparent stripe electrode groups arranged in parallel and a second substrate having a common transparent electrode are placed with the transparent electrode surfaces facing each other and spaced apart from each other. A liquid crystal layer is formed between the two substrates, a stepwise voltage is applied to each transparent stripe electrode of the first substrate, a predetermined voltage is applied to the common transparent electrode, and an electric field strength distribution is generated in the liquid crystal layer. In a light deflection element formed and deflected according to the refractive index distribution of the liquid crystal layer with respect to incident light generated by the electric field strength distribution, a dielectric is provided between the transparent stripe electrode group of the first substrate and the liquid crystal layer. Forming the body layer, the common transparent electrode of the second substrate having the same shape as the transparent stripe electrode of the first substrate, the transparent stripe electrode group of the second substrate and the liquid crystal layer During the dielectric Characterized in that to form a layer.

According to a second aspect of the present invention, in the optical deflection element according to the first aspect , the transparent stripe electrodes on the respective substrates are alternately arranged as viewed from the optical path .

The invention according to claim 3 is a first substrate having a plurality of transparent stripe electrode groups arranged in parallel, and a second substrate having a transparent electrode having the same shape as the transparent stripe electrode of the first substrate. Are arranged with a gap between the transparent electrode faces, a liquid crystal layer is formed between both substrates, and a voltage is applied to each transparent stripe electrode on the first substrate and each transparent stripe electrode on the second substrate. An optical deflection element for forming an electric field intensity distribution in a liquid crystal layer and deflecting light according to a refractive index distribution of the liquid crystal layer with respect to incident light generated by the electric field intensity distribution, wherein the transparent stripe electrode group of the first substrate and the A dielectric layer is formed between the liquid crystal layer and between the transparent stripe electrode group on the second substrate and the liquid crystal layer, and a voltage that changes stepwise is applied to each transparent stripe electrode on the first substrate. And the second substrate First, each transparent stripe electrode is set to a predetermined potential, and the potential difference applied between the corresponding first and second transparent stripe electrodes is changed stepwise to form an intensity distribution in the electric field in the thickness direction of the liquid crystal layer. Voltage applied to the transparent stripe electrode groups of the first and second substrates in a stepwise manner in the electrode arrangement direction to increase the potential difference between adjacent transparent stripe electrodes of each substrate. Thus, a second electric field application state in which an electric field is formed in the direction of the liquid crystal layer is formed .

According to a fourth aspect of the present invention, in the optical deflection element according to the third aspect, the transparent stripe electrodes on the substrates are alternately arranged as viewed from the optical path .

According to a fifth aspect of the present invention, the first substrate having the stripe-shaped transparent electrode group and the second substrate having the common transparent electrode are disposed with the transparent electrode surfaces facing each other and maintaining a predetermined interval. A liquid crystal layer is formed between the substrates, and a voltage that changes stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate. In the light deflection element that forms an electric field intensity distribution in the liquid crystal layer and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field intensity distribution, the transparent stripe electrode group, the liquid crystal layer, A dielectric layer is formed between the electrodes, and voltages applied to the transparent stripe electrodes of the first substrate are individually set .

According to the sixth aspect of the present invention, the first substrate having the stripe-shaped transparent electrode group and the second substrate having the common transparent electrode are disposed with the transparent electrode surfaces facing each other and maintaining a predetermined interval. A liquid crystal layer is formed between the substrates, and a voltage that changes stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate. In the light deflection element that forms an electric field intensity distribution in the liquid crystal layer and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field intensity distribution, the transparent stripe electrode group, the liquid crystal layer, A dielectric layer is formed between and the common transparent electrode of the second substrate is grounded .

According to the seventh aspect of the present invention, the first substrate having the stripe-shaped transparent electrode group and the second substrate having the common transparent electrode are disposed with the transparent electrode surfaces facing each other and maintaining a predetermined interval. A liquid crystal layer is formed between the substrates, and a voltage that changes stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate. In the light deflection element that forms an electric field intensity distribution in the liquid crystal layer and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field intensity distribution, the transparent stripe electrode group, the liquid crystal layer, When the electric field strength distribution formed in the liquid crystal layer is changed by forming a dielectric layer between the transparent stripe electrodes, the potential difference between the transparent stripe electrodes is reduced, and after passing through a substantially no electric field state, the transparent stripe electrodes Change in stages And applying a pressure.

The invention according to claim 8 is the optical deflection element according to claim 7 , wherein a voltage that changes stepwise is applied to each of the transparent stripe electrodes through a state in which the potential difference between the transparent stripe electrodes is small. To do.

According to the ninth aspect of the present invention, the first substrate having the stripe-shaped transparent electrode group and the second substrate having the common transparent electrode are disposed with the transparent electrode surfaces facing each other and maintaining a predetermined interval. A liquid crystal layer is formed between the substrates, and a voltage that changes stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate. In the light deflection element that forms an electric field intensity distribution in the liquid crystal layer and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field intensity distribution, the transparent stripe electrode group, the liquid crystal layer, Before applying a voltage for forming a predetermined electric field strength distribution in the liquid crystal layer, and at least one of the transparent stripe electrode and the transparent common electrode in the liquid crystal layer. The orientation state of And applying a voltage to straight.

The invention according to claim 10 includes: a first substrate having a stripe-shaped transparent electrode group; and a second substrate having a stripe electrode having the same shape as the stripe-shaped transparent electrode provided on the first substrate. The transparent electrode surfaces are opposed to each other and are maintained at a predetermined interval, a liquid crystal layer is formed between the substrates, and a voltage is applied to the stripe electrode group to distribute the electric field strength in the liquid crystal layer. And a transparent stripe electrode group provided on the first substrate and the second substrate, in the light deflection element that deflects light according to the alignment state in the liquid crystal layer generated according to the electric field intensity distribution; A dielectric layer is formed between the liquid crystal layer, a first voltage pattern that changes stepwise is applied to the transparent stripe electrodes of the first substrate, and the transparent stripes of the second substrate are applied. The electrode has a second step change The pressure pattern is applied, by a difference of said first and said second voltage patterns, characterized by being capable forming an electric field in the vertical direction or an oblique direction of the liquid crystal layer in the first electric field application state .

The invention according to claim 11 includes a first substrate having a stripe-shaped transparent electrode group, and a second substrate having a stripe electrode having the same shape as the stripe-shaped transparent electrode provided on the first substrate. The transparent electrode surfaces are opposed to each other and are maintained at a predetermined interval, a liquid crystal layer is formed between the substrates, and a voltage is applied to the stripe electrode group to distribute the electric field strength in the liquid crystal layer. And a transparent stripe electrode group provided on the first substrate and the second substrate, in the light deflection element that deflects light according to the alignment state in the liquid crystal layer generated according to the electric field intensity distribution; A dielectric layer is formed between the liquid crystal layer, a first voltage pattern that changes stepwise is applied to the transparent stripe electrodes of the first substrate, and the transparent stripes of the second substrate are applied. A second electric power that changes in steps to the electrode A first electric field application state in which a pattern is applied and an electric field can be formed in a vertical direction or an oblique direction in the liquid crystal layer according to a difference between the first and second voltage patterns; and the first electric field The second electric field application state in which a voltage pattern in a form in which the voltage pattern in the application state is reversed symmetrically with respect to the arrangement direction of the transparent stripe electrodes is switched .

  According to the present invention, since the dielectric layer is formed between the transparent stripe electrode group and the liquid crystal layer, it is possible to prevent a non-uniform electric field generated at the end of the transparent electrode or between the electrodes from being applied to the liquid crystal layer. it can. Further, since the electric field intensity distribution in the liquid crystal layer can be made uniform or smooth, the refractive index distribution is also smoothed, and the occurrence of aberration can be reduced.

  According to the present invention, the transparent stripe electrode group can be formed on both the substrates and the voltage application state can be individually set, so that the electric field distribution and direction in the liquid crystal layer can be freely set. In addition, since the dielectric layer is formed between the transparent stripe electrode group and the liquid crystal layer, the non-uniform electric field at the electrode end is dulled, and the electric field uniformity in the liquid crystal layer is also improved. Therefore, the refractive index distribution in the liquid crystal layer can be arbitrarily set, and the occurrence of aberration can be effectively reduced.

  According to the present invention, since the transparent stripe electrodes on the upper and lower substrates are alternately arranged, the influence of the decrease in transmittance due to the transparent electrodes becomes uniform. Further, since the periodic structure of the electric field strength is relaxed, the electric fields in the liquid crystal layer thickness direction and the layer direction can be made uniform.

  According to the present invention, the electric field in the thickness direction and the electric field in the layer direction of the liquid crystal layer can be switched by switching the voltage application state to the transparent stripe electrode group on the upper and lower substrates. Further, since the orientation direction of the liquid crystal molecules is electrostatically switched even when the light deflection operation is OFF, the response speed can be increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIGS. 1A to 1D are explanatory diagrams relating to an optical deflection element according to the first embodiment of the present invention. The configuration is shown in FIG. A stripe electrode 2 made of a transparent electrode material is formed on the surface of a first substrate 1 made of a transparent substrate such as glass or resin. As the transparent electrode material, an ITO film or the like is used and processed into a stripe shape by photolithography and etching. The width and interval of the stripe electrodes 2 are appropriately set according to a desired light deflection angle, liquid crystal birefringence, liquid crystal layer thickness, and the like.

  The present invention is characterized in that the dielectric layer 3 is formed on the transparent stripe electrode 2. As the dielectric layer 3, a highly transparent material such as glass or resin can be used. When a liquid crystal alignment film is formed on the dielectric layer 3, a heat treatment step for the alignment film is required. Therefore, it is preferable to use glass having excellent heat resistance as the dielectric layer 3.

  The thickness of the dielectric layer 3 is preferably about 1 μm to 200 μm, and is optimized according to the width and pitch of the transparent stripe electrode 2, but if it is thinner than this range, the electric field uniformizing effect in the liquid crystal layer 4 is small. If it is thicker than this, the voltage required to drive the liquid crystal layer 4 increases. For bonding the first substrate 1 and the dielectric layer 3, an optical adhesive such as a UV curing type can be used.

  A liquid crystal alignment film (not shown) may be formed on the surface of the dielectric layer 3. As the liquid crystal alignment film, a polyimide material or the like may be applied by a spin coating method or the like, and a rubbing process for causing homogeneous alignment may be performed. The rubbing treatment direction is preferably parallel to the linear deflection surface of the incident light. Further, it is preferable to give a pretilt angle by controlling the alignment film type and rubbing conditions.

  Depending on the characteristics of the liquid crystal material to be used, a homeotropic alignment film may be formed on the surface of the dielectric layer 3. In that case, a weak rubbing treatment may be performed to give the liquid crystal molecules on the homeotropic alignment film a slight pretilt angle of several degrees or less. By giving a slight pretilt angle to the homeotropic alignment, the uniformity of the alignment direction of liquid crystal molecules when no electric field is applied and when the electric field is driven can be improved, and the occurrence of domains can be reduced. Furthermore, a homogeneous alignment process may be performed on one substrate, a homeotropic alignment process may be performed on the other substrate, and a combination of the two may be used for hybrid alignment.

  An ITO film is formed as a common electrode 6 on the second substrate 5. A liquid crystal alignment film (not shown) may be formed on the ITO film. A cell is formed by facing the dielectric layer 3 of two substrates and the ITO film with a spacer (not shown) interposed therebetween. The spacer is preferably in the form of particles or film, and is preferably disposed outside the effective region through which light is transmitted.

  The spacer may be mixed with an adhesive and applied. The particle diameter and thickness of the spacer are set according to the thickness of the liquid crystal layer 4. As a method for forming the spacer, a thick film serving as a spacer member may be applied and formed on the substrate, and processed into a desired shape by a photolithography method. Alternatively, a separate mold may be formed, and the spacer member may be transferred and formed on the substrate. A photopolymer or the like can be used as the transfer forming member.

  The thickness d of the liquid crystal layer 4 defined by the height of the spacer portion is an effective refractive index distribution determined by the phase difference Δn · d required for the target light deflection angle and the electric field distribution in the liquid crystal layer 4. It is set by the difference Δn.

  A liquid crystal material is injected into the cell and then sealed with an adhesive to obtain an optical deflection element. As the liquid crystal material, nematic liquid crystal or smectic liquid crystal can be used, but the liquid crystal molecules are homogeneously aligned with respect to the electric field applied between the upper and lower substrates as used in general liquid crystal elements because of relatively good alignment. A nematic liquid crystal having positive dielectric anisotropy that changes from a homeotropic orientation to a homeotropic orientation is preferred. Alternatively, when the homeotropic alignment film is formed on the substrate surface as described above, the liquid crystal molecules have a negative dielectric anisotropy that changes from homeotropic alignment to homogeneous alignment with the application of electrolysis between the upper and lower substrates. Nematic liquid crystals can also be used. In general, it is relatively difficult to obtain uniform orientation of smectic liquid crystals, but by applying an electric field in the temperature lowering process after the liquid crystal material is injected, electrostatic force acts on the liquid crystal molecules, and the orientation can be improved.

  Different voltage is applied stepwise to each stripe electrode group of the first substrate 1 in the width direction of the stripe electrode. In the case of nematic liquid crystals, an alternating voltage of about ± several volts to several tens of volts is applied at a frequency of several tens to several hundreds of hertz. FIG. 1A shows an example of seven stripe electrodes. Here, when the homogeneous alignment film on the substrate surface is subjected to a rubbing process parallel to the linear polarization plane of incident light, the liquid crystal alignment direction when no electric field is applied is the left-right direction on the paper surface. V1 has a small voltage value and the liquid crystal molecules are in a state close to homogeneous alignment by rubbing. In V7, a liquid crystal molecule having a relatively large voltage value and positive dielectric anisotropy is homeostatic by electrostatic force that directs the molecular long axis in the electric field direction. Change to tropic orientation.

  Here, with respect to incident light having a plane of polarization parallel to the left-right direction on the paper surface, the refractive index is high in the homogeneously oriented part, and the refractive index is low in the homeotropically oriented part. Due to this difference in refractive index, a phase difference Δn · d is generated, and the emitted light is deflected as shown in FIG.

  In the vicinity of the stripe electrode 2, the potential distribution is also discontinuous and stepwise due to the discontinuity of the electrodes, but in the liquid crystal layer 4, the potential distribution becomes dull in the dielectric layer 3. ) As shown in FIG. Therefore, the refractive index distribution in the liquid crystal layer is also continuous as shown in FIG. 1C, and the aberration as a prism is reduced. Although one refractive index distribution is depicted in FIG. 1, the refractive index distribution may be changed like a periodic sawtooth shape by repeating the voltage application pattern by increasing the number of stripe electrodes.

  As a method of applying different potentials stepwise to each stripe electrode 2, a method of connecting an independent power source to each electrode, a method of connecting each stripe electrode with a resistance material, and relatively reducing both ends of the electrode group or at regular intervals. There is a method of dividing resistance by applying a large voltage. In that case, the resistive material is preferably formed on the stripe electrode surface of each substrate.

  When the electrode on the second substrate 5 is the common electrode 6, the electric lines of force in the liquid crystal layer 4 are perpendicular to the common electrode 6, so that the liquid crystal molecules are slanted as in the central portion of FIG. The balance between electrostatic force and force due to the elasticity of the liquid crystal layer is important to create a state in which the liquid crystal layer is aligned. Therefore, when the viscoelasticity of the liquid crystal layer changes due to temperature change or the like, the alignment state of the liquid crystal molecules may change.

  FIG. 2 is a configuration diagram of an optical deflection element according to the second embodiment of the present invention. In the second embodiment, as shown in FIG. 2, the electrodes on the second substrate 5 are also electrically formed independently by the stripe electrodes 2. For example, as shown in FIG. 2, by independently applying a potential to each stripe electrode 2 on the first and second substrates 1 and 5, a potential difference in the layer direction is also given simultaneously with a potential difference in the thickness direction of the liquid crystal layer 4. Therefore, an electric field can be applied in an oblique direction in the liquid crystal layer.

  In FIG. 2 and subsequent figures, a state in which a positive polarity is applied is shown for simplicity, but it is preferable to apply an AC electric field that switches to a state in which the polarity is reversed overall. Therefore, since an electrostatic force can be applied to align the liquid crystal molecules obliquely, a stable refractive index distribution can be formed even with a temperature change.

  In addition, it is expected that the characteristic of refractive index change with respect to the applied voltage changes linearly by applying an electric field in an oblique direction. Accordingly, a relatively large refractive index difference can be used even under voltage application conditions in which no aberration occurs, and a relatively large light deflection angle can be expected.

  A nonuniform electric field in the vicinity of each electrode is blunted by the dielectric layer, and a continuous electric field distribution is obtained in the liquid crystal layer 4. In addition, each stripe electrode 2 of the second substrate 5 may be grounded at the same potential or ground, and the same characteristics as in the first embodiment described above can be obtained. As a method of applying different potentials stepwise to each stripe electrode 2, a method of connecting an independent power source to each electrode, a method of connecting each stripe electrode with a resistance material, and relatively reducing both ends of the electrode group or at regular intervals. There is a method of dividing resistance by applying a large voltage. The resistance material is preferably formed on the stripe electrode surface of each substrate.

  In order to change the potential distribution between the first and second substrates 1 and 5 as shown in FIG. 2, the resistance value and the applied voltage value of the resistor formed on each substrate are changed. The voltage value pattern applied to each stripe electrode is experimentally determined in advance in correlation with the desired light polarization characteristics in accordance with the characteristics of the liquid crystal material used and the characteristics of the resistor. The transparent electrode forming the stripe electrode 2 is not completely transparent but slightly decreases in transmittance. When the positions of the stripe electrodes on the first and second substrates 1 and 5 are overlapped, a decrease in transmittance becomes remarkable.

  FIG. 3 is a configuration diagram of an optical deflection element according to the third embodiment of the present invention. In the third embodiment, since the transparent stripe electrodes 2 of the upper and lower substrates 1 and 5 are alternately arranged as shown in FIG. 3, the influence of the decrease in transmittance due to the transparent electrodes becomes uniform.

  Further, when the positions of the upper and lower electrodes coincide with each other, the electrode pitch acting on the vicinity of the center of the liquid crystal layer 3 is equal to the stripe electrode pitch, but when the positions of the upper and lower electrodes are alternately arranged, the vicinity of the center of the liquid crystal layer The electrode pitch acting on is equivalent to 1/2 the stripe electrode pitch. Therefore, since the periodic structure of the electric field strength accompanying the electrode pitch is reduced and relaxed, the electric field in the liquid crystal layer is made more uniform.

  When nematic liquid crystal is used for the above-mentioned light deflection element, the response of the liquid crystal molecules when the voltage is on is relatively fast because of the force of electrostatic energy, but the response of the liquid crystal molecules when the voltage is off is the response of the liquid crystal layer. There is a problem that it is relatively slow due to viscoelasticity and orientation regulating force.

  4A to 4C are explanatory diagrams relating to an optical deflection element according to the fourth embodiment of the present invention. In the fourth embodiment, as shown in FIG. 4A, a voltage that changes stepwise is applied to each transparent stripe electrode 2 of the first substrate 1, and each transparent stripe electrode 2 of the second substrate 5 is applied to the same. A first electric field application state in which the potential difference applied between the corresponding first and second transparent stripe electrodes 2 is changed stepwise to form an intensity distribution in the electric field in the liquid crystal layer thickness direction. Similarly, as shown in FIG. 4B, a voltage that changes stepwise in the electrode arrangement direction is similarly applied to the transparent stripe electrodes 2 of the first and second substrates 1 and 5 to reduce the potential difference between the upper and lower electrodes. The second electric field application state in which an electric field is formed in the layer direction of the liquid crystal layer 4 by increasing the potential difference between the adjacent transparent stripe electrodes.

  Since the second electric field application state exerts a force for returning to homogeneous alignment electrostatically in addition to the original viscoelasticity and alignment regulating force of the liquid crystal layer 4, the speed can be relatively increased. Further, in the fifth embodiment of the present invention, the first electric field application state is not limited to the case where one side is the same potential or grounded as shown in FIG. 4A, but in FIG. 2 of the second embodiment. Thus, a stepwise voltage may be applied to both substrates. In this case, an electrostatic force can also be applied to obliquely align the liquid crystal molecules in the first electric field application state, so that a stable refractive index distribution can be formed even with temperature changes. In addition, it can be expected that the characteristic of refractive index change with respect to the applied voltage changes linearly by applying an electric field in an oblique direction. Accordingly, a relatively large refractive index difference can be used even under a voltage application condition in which no aberration occurs, so that a large light change angle can be obtained.

  On the other hand, the second electric field application state is not limited to the upper and lower target electrode arrangement as shown in FIG. 4B, and the applied voltage value is changed to the electrode arrangement as in the third embodiment as shown in FIG. 4C. A voltage may be applied so that the upper and lower electrodes alternately change stepwise. Further, instead of increasing the voltage value stepwise, a voltage may be applied alternately to the stripe electrodes 2 of the substrates 1 and 5 as shown in FIG. In this case, even when the number of stripe electrodes 2 is large, a uniform horizontal electric field can be applied to the entire surface with a relatively small voltage value. Therefore, it is possible to reduce the aberration by optimizing the refractive index distribution and to perform high-speed driving like a dual frequency drive using a normal nematic liquid crystal by applying an electric field in the horizontal direction.

  In the switching between FIG. 4 (a) and FIG. 4 (b), the incident light as shown in FIG. 1 (d) is switched between the state in which the outgoing light is polarized in one direction and the state in which it goes straight. In the sixth embodiment, the refractive index distribution in the liquid crystal phase is inverted with respect to the object by switching to an applied voltage pattern in which FIG. 4A is reversed symmetrically, and FIG. 6A and FIG. As shown in FIG. 6B, a large deflection angle can be obtained in the left-right direction of the paper.

  However, considering the case where the voltage application pattern is directly switched from the state shown in FIG. 6A to the state shown in FIG. 6B, an electric field in the thickness direction from the no-field state is applied in the liquid crystal portion on the right side of the element. However, since the liquid crystal portion on the left side of the device is changed from the electric field application state in the thickness direction to the no electric field state, the response of the alignment change may be delayed.

  Therefore, in the seventh embodiment of the present invention, when the applied voltage pattern is reversed, as shown by the arrows in FIG. 6C, in the horizontal direction of the effective area of the liquid crystal element (stripe electrode arrangement direction), It changes from a large horizontal electric field application region (a state in which the potential difference between the stripe electrodes is large) to a small horizontal electric field application region (a state in which the potential difference between the stripe electrodes is small). The applied voltage pattern is controlled so as to continuously change to the vertical electric field application region. If the state of FIG. 6A is the same voltage pattern as FIG. 4A, the voltage value of each electrode is controlled as in the voltage pattern illustrated in FIG. 4C when the optical path deflection direction is switched. To do. In this case, since the electrostatic force for switching the left side of the element to the horizontal alignment state works, the entire region can be switched to the state of FIG. 6B at high speed. Alternatively, instead of temporarily applying the voltage pattern shown in FIG. 6C as an intermediate state, the pattern shown in FIG.

  When the liquid crystal alignment state in the element is switched to left-right symmetry as shown in FIG. 6, a liquid crystal alignment defect may occur in the element depending on the electric field strength and the pretilt angle. Here, FIG. 7 shows an enlarged alignment state in the vicinity of the left side of FIG. Although a vertical electric field is applied to the left end of FIG. 7A, when a horizontal electric field is applied as shown in FIG. 6C, vertically aligned liquid crystal molecules are rotated clockwise or as indicated by arrows in the figure. It changes to a horizontal alignment state to rotate counterclockwise. At this time, when rotating clockwise, a defect occurs at the boundary with the region that has already been oriented counterclockwise as shown in FIG. This defect causes light scattering and is not preferable. On the other hand, when rotated counterclockwise, no defect occurs as shown in FIG. The rotation direction when switching from the vertical alignment state to the horizontal alignment state can also be controlled by applying a pretilt angle by an alignment process. According to an eighth aspect of the present invention, when the optical path deflection direction is switched, a voltage pattern for temporarily uniforming the liquid crystal alignment state on the entire surface of the element is applied, and then the voltage pattern in the optical path deflection state is applied. To do. For example, as an intermediate state for switching from the state shown in FIG. 6A to the state shown in FIG. 6B, a voltage pattern that gives a full horizontal electric field as shown in FIG. 8A or a full vertical electric field as shown in FIG. After the application, a desired voltage pattern is applied. For example, a uniform horizontal electric field can be applied with a voltage pattern as shown in FIGS. 4B, 4C, and 5. FIG. Alternatively, each of the stripe electrode group on the first substrate surface and the stripe electrode group on the second substrate surface is switched so that a constant voltage is applied, and a potential difference is applied between the two electrode groups, A uniform vertical electric field can be applied between the second substrates. Here, when the liquid crystal to be used is a nematic liquid crystal, it is preferable to apply an alternating voltage. As described above, since the continuous alignment distribution is formed after the liquid crystal alignment of the entire device is uniformly aligned in one direction, the occurrence of discontinuous alignment defects due to the mismatch of the liquid crystal rotation direction as shown in FIG. Can be prevented.

  In the present invention, a desired smooth electric field intensity distribution or a uniform horizontal electric field or a uniform vertical electric field can be freely applied to the liquid crystal layer by a combination of stripe electrode groups and dielectric layers capable of applying a desired voltage pattern. It is characterized by using an optical element, and is not limited to the voltage values exemplified in the above figure or a combination thereof.

  An ITO film having a thickness of 1000 mm was formed on two glass substrates having a size of 3 cm × 4 cm and a thickness of 1 mm using a sputtering apparatus. The ITO film of the first substrate was processed into a stripe shape by photolithography and wet etching. The width of the stripe electrode in the effective region was 50 μm, the length was 2 mm, the width of the non-electrode portion was 50 μm, and the electrode pitch was 100 μm. Twenty stripe electrodes were formed in an effective width of 2 mm. Outside the effective area on the substrate, the width of the electrode was increased to 200 μm to facilitate the extraction of the electrical wiring.

  A glass sheet (dielectric layer) having a size of 1 cm square and a thickness of 20 μm was bonded onto the ITO surface of the effective area of the first substrate using an ultraviolet curable adhesive. A polyimide alignment film having a thickness of 600 mm was applied on the glass sheet surface by spin coating. The alignment film surface was rubbed in parallel with the arrangement direction of the stripe electrodes (perpendicular to the longitudinal direction of the stripe electrodes). The pretilt angle was set to about 1 degree.

  An alignment film was similarly formed on the ITO film of the second substrate, and was similarly rubbed. Cells were formed by adhering spacer particles so that the rubbing direction of the two substrates was in the antiparallel direction. A spacer having a particle size of 20 μm was mixed with an adhesive, applied outside the effective area, and cured. A nematic liquid crystal was injected into the cell and sealed to prepare an optical deflection element.

  Conductive wires made of a flexible substrate were connected to the stripe electrodes of the first substrate, and the conductive wires were connected in series with a resistance of 100Ω. The common electrode of the second substrate was grounded. A He—Ne laser beam having a beam diameter of 1 mm was applied to the effective area through a linear deflection plate, and the deflection angle was measured from the change in the projection position of the beam.

  When an AC voltage (50 Hz) of ± 4 V and ± 2 V are applied to both ends of the series resistor connecting the stripe electrode group of the first substrate with the same polarity, the voltage value divided by resistance is applied to each stripe electrode. Were applied individually, and a refractive index distribution of the liquid crystal layer was generated in the arrangement direction of the stripe electrodes. The deflection angle by voltage application at an element temperature of 30 ° C. was 2 minutes, and the response speed was about 10 msec when the voltage was applied and about 30 msec when the voltage was OFF. At this time, there was no change in the beam shape of the transmitted light, and an optical deflection element with little aberration was obtained.

  However, under the same voltage application conditions at an element temperature of 40 ° C., it was found that although the deflection angle was the same, a slight change in the beam shape was observed, and a slight aberration occurred due to the temperature change.

(Comparative example)
An optical deflection element was produced in the same manner as in Example 1 except that the glass sheet as the dielectric layer was not attached on the first substrate. In the comparative example, since there is no dielectric layer, the applied voltage value can be set small. Therefore, an alternating voltage (50 Hz) of ± 2 V is applied to one end of the series resistor connecting the stripe electrode group of the first substrate and ± 1 V is applied to the other end. Applied with the same polarity. The deflection angle by voltage application at an element temperature of 30 ° C. was the same as 2 minutes.

  The same stripe electrode, dielectric layer and alignment film as the first substrate of Example 1 were also formed on the second substrate. A cell was prepared by attaching a 20 μm spacer so that the positions of the stripe electrodes on both substrates coincided. Nematic liquid crystal similar to that in Example 1 was injected, and conductive wires made of a flexible substrate were connected to the stripe electrodes of both substrates, and the conductive wires were connected in series with a resistance of 100Ω.

  A He—Ne laser beam having a beam diameter of 1 mm was applied to the effective area through a linear deflection plate, and the deflection angle was measured from the change in the projection position of the beam. As shown in FIG. 2, alternating voltages of 12V and 0V are applied to both ends of the stripe electrode group of the first substrate and 6V and 0V are applied to both ends of the stripe electrode group of the second substrate with the same polarity. Each stripe electrode was individually applied with a resistance-divided voltage value, and a refractive index distribution of the liquid crystal layer was generated in the stripe electrode arrangement direction.

  The deflection angle by voltage application at an element temperature of 30 ° C. was 2.5 minutes, and the response speed was about 10 msec when the voltage was applied and about 30 msec when the voltage was OFF. Further, there was no change in the beam shape of the transmitted light even at an element temperature of 40 ° C., and a stable light deflection element with little aberration with respect to the temperature change was obtained.

  However, when the effective region of the device was observed with a microscope using transmitted light, a portion with and without an ITO stripe electrode was clearly observed as a difference in transmittance. There is a concern that this difference in transmittance may be a problem depending on the application field of the optical deflection element.

  In the same manner as in Example 2, a stripe electrode, a dielectric layer, and an alignment film were formed on both substrates. A cell was prepared by attaching a 20 μm spacer so that the stripe electrodes on both substrates were alternately positioned. Nematic liquid crystal similar to that in Example 2 was injected, and conductive wires made of a flexible substrate were connected to the stripe electrodes of both substrates, and the conductive wires were connected in series with a resistance of 100Ω.

  A He—Ne laser beam having a beam diameter of 1 mm was applied to the effective area through a linear deflection plate, and the deflection angle was measured from the change in the projection position of the beam. As in Example 2, alternating voltages of 12 V and 0 V were applied to both ends of the stripe electrode group on the first substrate and 6 V and 0 V were applied to both ends of the stripe electrode group on the second substrate with the same polarity. Each stripe electrode was individually applied with a resistance-divided voltage value, and a refractive index distribution of the liquid crystal layer was generated in the stripe electrode arrangement direction.

  The deflection angle by voltage application at an element temperature of 30 ° C. was 2.5 minutes, and the response speed was about 10 msec when the voltage was applied and about 30 msec when the voltage was OFF. Further, there was no change in the beam shape of the transmitted light even at an element temperature of 40 ° C., and a stable light deflection element with little aberration with respect to the temperature change was obtained.

  When the effective area of the device was observed with a microscope using transmitted light, it was observed that the ITO stripe electrode was disposed throughout. Therefore, an optical deflecting element having a uniform transmittance was obtained.

  Using the same optical deflection element as in Example 2, 12 V and 0 V are applied to both ends of the stripe electrode group of the first substrate, and 6 V is applied to both ends of the stripe electrode group of the second substrate as shown in FIG. A first electric field application state in which an AC voltage of 0 V is applied with the same polarity and 12 V and 0 V at both ends of the stripe electrode group of the first substrate as shown in FIG. The second electric field application state in which alternating voltages of 12 V and 0 V were applied to both ends with the same polarity was switched.

  The time required for the liquid crystal to change from the homogeneous alignment state to the alignment distribution state of FIG. 9 by the first electric field application state was about 10 msec, which was the same as the other examples, but the homogeneous alignment state by the second electric field application state. The time to return to has been reduced to about 10 msec. This is considered to be due to the fact that, in addition to the original viscoelasticity and alignment regulating force of the liquid crystal layer, a force to return to homogeneous alignment also acts electrostatically by the second electric field application state. Further, when the element temperature was 30 ° C. and 40 ° C., the shape of the transmitted light beam was not changed, and the aberration was small even with respect to the temperature change. Accordingly, an optical deflection element having a high response time and excellent stability with respect to a temperature change is obtained.

  Using the same optical deflection element as in Example 2, 12 V and 0 V are applied to both ends of the stripe electrode group of the first substrate, and 6 V is applied to both ends of the stripe electrode group of the second substrate as shown in FIG. A first electric field application state in which an AC voltage of 0 V was applied with the same polarity and a second electric field application state in which the voltage values in FIG. As a result, it was considered that the liquid crystal alignment states as shown in FIGS. 6A and 6B were switched, and a relatively large deflection angle of 5.0 minutes was obtained.

  However, when the beam shape of the transmitted light was observed, the disturbance of the shape at the time of switching the deflection direction was relatively large, and the time until switching after forming a normal beam shape was relatively slow, about 30 msec. This is presumably because the response speed of the liquid crystal at the end of the element is relatively slow.

  By using the same optical deflecting element as in Example 2, a large horizontal electric field application region (potential difference between stripe electrodes) in the horizontal direction of the effective region of the liquid crystal element as shown in FIG. Changes from a large electric field application region to a small horizontal electric field application region (a state in which the potential difference between the stripe electrodes is small), and continuously changes from a small vertical electric field application region to a large vertical electric field application region through a substantially no electric field region. A voltage pattern was applied as follows. Through the above process, the first voltage application state shown in FIG. 6C was switched to the second voltage application state in which a symmetrical voltage pattern on the paper surface was applied. As a result, the deflection angle was as large as 5.0 minutes, and the response time was about 10 msec. However, when the liquid crystal layer at the time of switching was observed, light scattering that was presumed to be due to alignment defects occurred at the end of the element.

  Using the same optical deflection element and voltage application means as in the sixth embodiment, the voltage application means is applied so that the pulsed voltage pattern shown in FIG. 8C is applied for about 5 msec as an intermediate state when the deflection direction is switched. It was set. As a result, characteristics with a deflection angle of 5.0 minutes and a response time of about 13 msec were obtained. Although the response time was delayed as compared with Example 6, no light scattering occurred during switching.

  According to the above invention, the following effects can be obtained.

  According to the present invention, in the first electric field application state, an electrostatic force can be applied to obliquely align the liquid crystal molecules, so that a stable refractive index distribution can be formed even with a temperature change. . In addition, it is expected that the characteristic of refractive index change with respect to the applied voltage changes linearly by applying an electric field in an oblique direction. Accordingly, a relatively large refractive index difference can be used even under voltage application conditions in which no aberration occurs, and a relatively large light deflection angle can be expected.

  In addition, according to the present invention, since the refractive index distribution in the liquid crystal layer is reversed symmetrically, a large deflection angle can be obtained.

  In addition, according to the present invention, there is provided an optical deflection element that can obtain a large deflection angle and exhibits high-speed response.

  In addition, according to the present invention, when the optical path deflection direction is switched, a continuous alignment distribution is formed after the liquid crystal alignment of the entire element is temporarily uniformly aligned in one direction of the horizontal alignment state or the vertical alignment state. In addition, it is possible to prevent the occurrence of discontinuous alignment defects due to the mismatch of the liquid crystal rotation directions.

  Further, according to the present invention, a desired smooth electric field strength distribution or a uniform horizontal electric field or a uniform vertical electric field can be freely applied to the liquid crystal layer by a combination of a stripe electrode group capable of applying a desired voltage pattern and a dielectric layer. Is possible. As described above, an optical element capable of controlling the electric field distribution in the liquid crystal layer to a desired pattern is provided.

(A) is a figure of the optical deflection | deviation element to which this invention is applied. (B) is a figure showing the electric potential applied to each stripe electrode. (C) is a figure showing refractive index distribution when a voltage is applied to each stripe electrode. (D) is a figure showing the direction where light is refracted when a voltage is applied to each stripe electrode. It is the figure which applied the voltage which changes in steps to the optical deflection | deviation element to which this invention is applied. It is a figure of the optical deflection | deviation element which has arrange | positioned the transparent stripe electrode of the upper and lower board | substrate alternately. (A) is the figure which applied the voltage which changes in steps only to an upper board | substrate. (B) is the figure which applied the voltage which changes in steps to both board | substrates. (C) is the figure which changed the voltage alternately in steps with the upper and lower electrodes of the optical deflection element in which the transparent stripe electrodes of the two substrates are alternately arranged. It is the figure which applied the voltage to the transparent stripe electrode group of the optical deflection | deviation element to which this invention is applied alternately. (A) is the figure which applied the voltage which changes in steps only to an upper board | substrate. (B) is the figure which reversed the voltage application pattern of (a) symmetrically. (C) is the figure which applied the voltage which changes in steps toward the edge from the center of both board | substrates. (A), (b), and (c) are the figures in which the liquid crystal orientation defect produced in the optical deflection element to which this invention was applied. (A) is the figure which applied the horizontal electric field to the optical deflection | deviation element to which this invention is applied. (B) is the figure which applied the perpendicular electric field to the optical deflection | deviation element to which this invention is applied. It is explanatory drawing of a prior art example. It is explanatory drawing of a prior art example. It is explanatory drawing of a prior art example. It is explanatory drawing of the conventional optical deflection | deviation element. (A) is a figure showing the electric potential applied to each stripe electrode. (B) is a figure showing refractive index distribution when a voltage is applied to each stripe electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 Stripe electrode 3 Dielectric layer 4 Liquid crystal layer 5 2nd board | substrate 6 Common electrode

Claims (11)

A first substrate having a plurality of transparent stripe electrode groups arranged in parallel and a second substrate having a common transparent electrode are placed with the transparent electrode surfaces facing each other, and a liquid crystal layer is provided between the substrates. A stepwise voltage is applied to each transparent stripe electrode of the first substrate and a predetermined voltage is applied to the common transparent electrode to form an electric field strength distribution in the liquid crystal layer. In an optical deflection element that deflects light according to the refractive index distribution of the liquid crystal layer with respect to incident light,
Forming a dielectric layer between the transparent stripe electrode group of the first substrate and the liquid crystal layer ;
The common transparent electrode of the second substrate has the same shape as the transparent stripe electrode of the first substrate;
An optical deflection element , wherein the dielectric layer is formed between the transparent stripe electrode group on the second substrate and the liquid crystal layer . 2. The optical deflection element according to claim 1 , wherein the transparent stripe electrodes on the substrates are alternately arranged as viewed from the optical path . A first substrate having a plurality of transparent stripe electrode groups arranged in parallel and a second substrate having a transparent electrode having the same shape as the transparent stripe electrode of the first substrate are opposed to the transparent electrode surface. A liquid crystal layer is formed between the two substrates, and a voltage is applied to each transparent stripe electrode on the first substrate and each transparent stripe electrode on the second substrate to generate an electric field strength distribution in the liquid crystal layer. In the light deflection element that deflects light according to the refractive index distribution of the liquid crystal layer with respect to incident light generated by the electric field strength distribution,
Forming a dielectric layer between the transparent stripe electrode group of the first substrate and the liquid crystal layer and between the transparent stripe electrode group of the second substrate and the liquid crystal layer;
A voltage that changes stepwise is applied to each transparent stripe electrode of the first substrate, the transparent stripe electrodes of the second substrate are set to a predetermined potential, and the corresponding first and second transparent stripes are applied. In the first electric field application state in which the potential difference applied between the electrodes is changed stepwise to form an intensity distribution in the electric field in the thickness direction of the liquid crystal layer, and in each of the transparent stripe electrode groups of the first and second substrates A voltage that changes stepwise in the electrode arrangement direction is applied to increase the potential difference between adjacent transparent stripe electrodes of each substrate, thereby forming a second electric field application state in which an electric field is formed in the layer direction of the liquid crystal layer. light deflection element shall be the. 4. The optical deflection element according to claim 3 , wherein the transparent stripe electrodes on the respective substrates are alternately arranged as viewed from the optical path . A first substrate having a stripe-shaped transparent electrode group and a second substrate having a common transparent electrode are placed with the transparent electrode surfaces facing each other with a predetermined interval, and a liquid crystal is interposed between the substrates. A layer is formed, and a voltage changing stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate, whereby an electric field strength is applied in the liquid crystal layer. In an optical deflection element that forms a distribution and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field strength distribution,
Forming a dielectric layer between the transparent stripe electrode group and the liquid crystal layer;
A light deflection element , wherein a voltage applied to each transparent stripe electrode of the first substrate is individually set . A first substrate having a stripe-shaped transparent electrode group and a second substrate having a common transparent electrode are placed with the transparent electrode surfaces facing each other with a predetermined distance therebetween, and a liquid crystal is interposed between the substrates. A layer is formed, and a voltage that changes stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate to generate an electric field strength in the liquid crystal layer. In an optical deflection element that forms a distribution and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field strength distribution,
Forming a dielectric layer between the transparent stripe electrode group and the liquid crystal layer ;
An optical deflection element , wherein the common transparent electrode of the second substrate is grounded . A first substrate having a stripe-shaped transparent electrode group and a second substrate having a common transparent electrode are placed with the transparent electrode surfaces facing each other with a predetermined interval, and a liquid crystal is interposed between the substrates. A layer is formed, and a voltage changing stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate, whereby an electric field strength is applied in the liquid crystal layer. In an optical deflection element that forms a distribution and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field strength distribution,
Forming a dielectric layer between the transparent stripe electrode group and the liquid crystal layer;
When changing the electric field strength distribution formed in the liquid crystal layer,
The smaller the potential difference between the transparent stripe electrodes, substantially through the field-free state, the optical deflection element you and applying a voltage which changes stepwise with each transparent stripe electrodes. 8. The optical deflection element according to claim 7, wherein a voltage that changes stepwise is applied to each of the transparent stripe electrodes through a state in which the potential difference between the transparent stripe electrodes is small . A first substrate having a stripe-shaped transparent electrode group and a second substrate having a common transparent electrode are placed with the transparent electrode surfaces facing each other with a predetermined interval, and a liquid crystal is interposed between the substrates. A layer is formed, and a voltage changing stepwise is applied to the transparent stripe electrode group, and a predetermined voltage is applied to the common transparent electrode of the second substrate, whereby an electric field strength is applied in the liquid crystal layer. In an optical deflection element that forms a distribution and deflects light according to the alignment state in the liquid crystal layer generated according to the electric field strength distribution,
Forming a dielectric layer between the transparent stripe electrode group and the liquid crystal layer;
Before applying a voltage for forming a predetermined electric field strength distribution in the liquid crystal layer, the alignment state in the liquid crystal layer is made parallel or perpendicular to at least one of the transparent stripe electrode and the transparent common electrode. optical deflection element you and applying a voltage. A first substrate having a stripe-shaped transparent electrode group and a second substrate having a stripe electrode having the same shape as the stripe-shaped transparent electrode provided on the first substrate are opposed to each other. A liquid crystal layer is formed between the substrates, and a voltage is applied to the stripe electrode group to form an electric field strength distribution in the liquid crystal layer. In the light deflection element that deflects light according to the alignment state in the liquid crystal layer generated according to
Forming a dielectric layer between the liquid crystal layer and the transparent stripe electrode group provided on the first substrate and the second substrate;
Applying a first voltage pattern that changes stepwise to each transparent stripe electrode of the first substrate;
Applying a second voltage pattern that changes stepwise to each transparent stripe electrode of the second substrate,
Wherein the difference between the first and the second voltage pattern, the first optical deflecting elements you characterized in that the electric field application state to allow an electric field in the vertical direction or an oblique direction of the liquid crystal layer. A first substrate having a stripe-shaped transparent electrode group and a second substrate having a stripe electrode having the same shape as the stripe-shaped transparent electrode provided on the first substrate are opposed to each other. A liquid crystal layer is formed between the substrates, and a voltage is applied to the stripe electrode group to form an electric field strength distribution in the liquid crystal layer. In the light deflection element that deflects light according to the alignment state in the liquid crystal layer generated according to
Forming a dielectric layer between the liquid crystal layer and the transparent stripe electrode group provided on the first substrate and the second substrate;
Applying a first voltage pattern that changes stepwise to each transparent stripe electrode of the first substrate;
Applying a second voltage pattern that changes stepwise to each of the transparent stripe electrodes of the second substrate;
The voltage pattern of the first electric field application state in which the electric field can be formed in the vertical direction or the oblique direction in the liquid crystal layer by the difference between the first and second voltage patterns, and the voltage pattern of the first electric field application state the second optical deflecting elements you characterized by switching the electric field application state of applying a voltage pattern of the shape obtained by inverting symmetrically with respect to the arrangement direction of the transparent stripe electrodes.

Images