Patent ID: 12210247

EMBODIMENT OF THE INVENTION

First Embodiment

The liquid crystal element100according to the first embodiment of the present invention will be described below.

FIG.1AandFIG.1Bshow schematic diagrams for explaining the schematic configuration of a liquid crystal element100according to the first embodiment. As shown inFIG.1A, the liquid crystal element100has a liquid crystal layer LC sandwiched between a transparent substrate B1and a transparent substrate B2.FIG.1Bis a diagram for schematically explaining the arrangement of electrode structures in the liquid crystal element100. As shown in the figure, in the liquid crystal element100, a center electrode CT is arranged at the center, and a plurality of arc-shaped unit-electrodes U1and U2are arranged concentrically around the center electrode CT.

In the liquid crystal element100of this embodiment, the unit-electrode U1is arranged on the center side, and the unit-electrode U2is arranged on the outer peripheral side. The widths of the unit-electrodes U1and U2decrease as they approach the outer periphery.

FIG.1Cis a schematic diagram of a refractive index distribution RF appearing in a cross section in an arbitrary direction passing through the center of the liquid crystal element100inFIG.1B. In the liquid crystal element100, an electric field is applied to the liquid crystal layer LC by voltage being supplied to the center electrode CT and each of the unit-electrodes U1and U2, thereby generating a saw-tooth refractive index distribution RF. Further, the refractive index distribution RF is formed to be substantially symmetrical about the optical axis LA, and, in the case of the planar view, the undulations of the refractive index are distributed concentrically.

The potential gradient generated from the center electrode CT and each unit-electrode U1, U2corresponds to each saw-tooth undulation in the saw-tooth-like refractive index distribution, and the liquid crystal element100functions as a convex Fresnel lens whose focal length can be varied. In addition, the planar view in this specification refers to viewing from the direction of the optical axis LA in the liquid crystal element100, that is, from a direction perpendicular to the transparent substrate B1.

Next, the unit-electrode U1of the liquid crystal element100in this embodiment will be explained usingFIG.2andFIG.3, and then the unit-electrode U2will be explained usingFIG.4andFIG.5, etc.

FIG.2is a schematic diagram for explaining the planar configuration of one unit-electrode U1.

As shown inFIG.1BandFIG.2, the unit-electrode U1of this embodiment is defined by an arcuate region of approximately 90 degrees, and is configured to include the first electrode E1and the second electrode E2, they are formed linearly. Furthermore, the unit-electrode U1has a space between the first electrode E1and the second electrode E2that is wider than the line width of these, and by applying different voltages to the first electrode E1and the second electrode E2, a potential gradient can be generated in the space.

The first electrode E1and the second electrode E2extend in an arc shape along the outer shape of each unit-electrode U1, and are connected to the first lead wire71and the second lead wire72, respectively, to form a comb-tooth, or comb-teeth, shape. In the two unit-electrodes U1that are adjacent to each other in the radial direction, the first electrode E1of the unit-electrode U1arranged on the outer circumference side and the second electrode E2of the unit-electrode U1arranged on the inner circumference side are placed adjacent to each other with a narrow space between them. In addition, the first lead wire71and the second lead wire72extend in the radial direction and are arranged between the unit-electrodes U1(between the unit-electrodes U2) that are adjacent to each other in the circumferential direction inFIG.1B.

Furthermore, the center electrode CT disposed at the center of the liquid crystal element100has a fan-shaped (or other shape such as a disk shape) core electrode CC instead of the first electrode E1, and a potential gradient can be generated in the region between the second electrode E2connected to the lead wire72and the core electrode CC.

FIG.3is a schematic diagram for explaining the cross section inFIG.2, but some components are omitted for simplification. The cross section inFIG.2is a radial cross section passing through a position corresponding to the center of the concentric arrangement of each unit-electrode U1. In the following, the structure of the unit-electrode U1will be explained in more detail usingFIG.3, and the potential distribution applied to the liquid crystal layer LC by the unit-electrode U1and the refractive index distribution caused by the same potential distribution will be explained.

The liquid crystal layer LC inFIG.3is sandwiched between a substrate located at the upper side of the figure (transparent substrate B1inFIG.1) and a substrate located at the lower side in the figure (transparent substrate B2inFIG.1). The former substrate is constructed by laminating a first electrode E1, a second electrode E2, an insulating layer IS1, a resistance layer HR, and an insulating layer IS2on a glass substrate (not shown inFIG.3), and the latter substrate is constructed by laminating a counter electrode E3on a glass substrate (not shown inFIG.3).

In the transparent substrate B1, a first electrode E1and a second electrode E2are formed on a glass substrate, and an insulating layer IS1is laminated so as to bury the first electrode E1and the second electrode E2. Further, a resistive layer HR is laminated on the insulating layer IS1, and an insulating layer IS2is further arranged to fill in the space between the resistive layers HR. Furthermore, in the transparent substrate B2, a counter electrode E3is formed on the glass substrate. Further, the transparent substrate B1and the transparent substrate B2have an alignment film at the interface of the liquid crystal layer LC, but this is not shown for simplicity.

The liquid crystal layer LC is, for example, a nematic liquid crystal, and the orientation of the liquid crystal becomes a homogeneous orientation in an environment without an electric field where no voltage is applied from the first electrode E1and the second electrode E2, and the color of the liquid crystal is transparent. Further, the thickness of the liquid crystal layer LC in this embodiment is preferably 5 μm or more and 30 μm or less.

The first electrode E1and the second electrode E2are formed of a transparent conductive film such as ITO (Indium Tin Oxide). Further, as shown inFIG.3, the area AR within the unit-electrode U1is defined by the space between the first electrode E1and the second electrode E2, and is interposed between the first electrode E1and the second electrode E2. The width of the region AR is larger than the line widths of the first electrode E1and the second electrode E2.

The insulating layer IS1is a transparent electrical insulator, and is formed of silicon dioxide (SiO2), for example. The insulating layer IS1in this embodiment is laminated so as to bury the structures such as the first electrode E1, the second electrode E2, the first lead wire71, and the second lead wire72. Further, the insulating layer IS2is laminated so as to fill the space between the resistive layers HR formed on the insulating layer IS1. The insulating layer IS2may be formed by burying the resistive layer HR with silicon dioxide similar to the insulating layer IS1, or by burying the resistive layer HR with an alignment film extending at the interface of the liquid crystal layer LC.

The resistance layer HR has a larger electrical resistivity than the first electrode E1and the second electrode E2, and a smaller electrical resistivity than the insulating layer IS1made of silicon dioxide, for example, and is composed of a transparent film such as (ZnO). The sheet resistivity of the resistance layer HR is larger than each of the sheet resistivity of the first electrode E1and the sheet resistivity of the second electrode E2, and is smaller than the sheet resistivity of the insulating layer IS1. The sheet resistivity of a material is the value obtained by dividing the electrical resistivity of the material by the thickness of the material.

Further, it is preferable that the electrical resistivity of the resistance layer be 1 Ω·m or more and the sheet resistivity of the resistance layer HR be 1×102Ω/sq or more and or less than 1×1011Ω/sq.

In addition, the planar shape of the resistance layer HR of the unit-electrode U1in this embodiment is an arcuate shape with a width slightly narrower than the width of the unit-electrode U1, and it is formed by dividing it so that there is a space between the resistance layers HR of another adjacent unit-electrode U1. It is preferable that the resistance layer HR be formed so as to be electrically isolated from the resistance layer HR in another unit-electrode U1. Further, the resistance layer HR is arranged in a region AR between the first electrode E1and the second electrode E2when viewed in a plan view. As shown inFIG.3, the resistance layer HR extends from directly below the first electrode E1to directly below the second electrode E2, and it is preferable that it be formed so as overlap at least a portion of the first electrode E1and at least a portion of the second electrode E2. However, it is not necessarily limited to such an aspect.

Further, as shown inFIGS.2and3, the first electrode E1of the unit-electrode U1is formed along the second electrode E2of another adjacent unit-electrode U1, and the second electrode E2of the unit-electrode U1is formed along the first electrode E1of another adjacent unit-electrode U1. An insulating layer IS1is disposed at the boundary between the first electrode E1of the unit-electrode U1and the second electrode E2of the other adjacent unit-electrode U1, and between the second electrode E2of the unit-electrode U1and the first electrode E1of the other adjacent the unit-electrode U1, and the resistance layers HR between adjacent unit-electrodes are separated by an insulating layer IS2. Furthermore, as shown inFIG.3, the liquid crystal layer LC in this embodiment is configured such that the liquid crystal material can move toward another unit-electrode at the boundary between adjacent unit-electrodes.

In this embodiment, as shown inFIG.2andFIG.3, the boundary between unit-electrodes is defined at the center of the insulating layer IS1interposed between radially adjacent unit-electrodes.

Further, the unit-electrode U1of this embodiment, the first electrode E1, the second electrode E2, and the resistance layer HR included therein extend in the circumferential direction of concentric circles and are formed in an arc shape, and these widths refer to the size corresponding to the thickness in the radial direction of the concentric circles.

The width of the insulating layer IS1interposed between two radially adjacent unit-electrodes U1(between unit-electrodes U2) may be, for example, 15 μm or less and 5 μm or more. In addition, the width may be narrowed depending on the distance from the optical axis LA of the liquid crystal element100.

The counter electrode E3is formed in a planar shape on the transparent substrate B2using a transparent conductive film such as ITO, and is supplied with a ground potential (0V). However, the counter electrode E3is not necessarily limited to such a mode.

Next, the potential distribution and refractive index distribution caused in the liquid crystal layer LC by the unit-electrode U1will be explained.

First, a first voltage V1is supplied to the first electrode E1via the first lead wire71based on an input from a control section (not shown) in the liquid crystal element100. Similarly, the second voltage V2is also supplied to the second electrode E2from the control section via the second lead wire72. Although the first voltage V1and the second voltage V2in this embodiment are rectangular wave alternating current voltages and have the same frequency and phase, the phases and frequencies do not necessarily have to be same, and it does not have to be rectangular wave AC voltage. Further, the maximum amplitude of the first voltage V1and the second voltage V2is set to be, for example, 10 V or less, and the frequency is set to, for example, 10 Hz or more and 5 MHz or less.

Here, the first voltage V1and the second voltage V2are different voltages, and when the second voltage V2has a higher effective value than the first voltage V1, as shown inFIG.3, liquid crystal molecules change from a state parallel to the transparent substrate B1to a state standing vertically, from the first electrode E1side to the second electrode E2side. Specifically, a liquid crystal layer LC is interposed between the first electrode E1and the second electrode E2and the counter electrode E3, and a resistive layer HR is further arranged between the first electrode E1and the second electrode E2, in planar view, thereby a potential distribution that gradually changes from the potential corresponding to the second voltage V2to the potential corresponding to the first voltage V1is generated, and as a result, each unit-electrode U1causes a refractive index gradient in the liquid crystal layer LC. Further, the refractive index gradient caused in the liquid crystal layer LC changes depending on the width of the region AR in the unit-electrode U1, and the gradient tends to become steeper as the width becomes narrower.

Next, the configuration of the unit-electrode U2in this embodiment will be explained usingFIG.4andFIG.5.FIG.4is a schematic diagram for explaining the planar configuration of the unit-electrode U2, and shows an example of the unit-electrode U2of this embodiment, andFIG.5is a diagram for explaining the V-V cross section inFIG.4. Like the unit-electrode U1, the unit-electrode U2is configured to be able to generate a refractive index gradient in the liquid crystal layer LC in the region AR.

FIG.4shows two unit-electrodes U2arranged adjacent to each other in the circumferential direction, and a first lead wire71and the like are interposed between the two unit-electrodes U2. Further, as shown inFIGS.4and5, the unit-electrode U2is different from the unit-electrode U1in that it has an auxiliary electrode EC, and is common to the unit-electrode U1in that it has the configuration of the first electrode E1, the second electrode E2, etc.

The auxiliary electrode EC is made of a transparent conductive film such as ITO, like the first electrode E1and the like. As shown inFIG.4, the auxiliary electrode EC in this embodiment is formed in an arc shape along the first electrode E1. Further, the auxiliary electrode EC is connected to a third lead wire73via a lead wire connection section74, and is supplied with voltage from a control section (not shown). Further, the first lead wire71and the second lead wire72are covered with an insulating layer IL, and the lead wire connecting section74is connected to the third lead wire73and the auxiliary electrode EC by straddling the first lead wire71covered with the insulating layer IL. Since the auxiliary electrode EC of the other unit-electrode U2is also connected, to the third lead wire73, the auxiliary electrode EC and the third lead wire73have a comb-like structure.

In particular, the auxiliary electrode EC is formed in a linear shape with a line width that is equal to or less than the line width of at least one of the first electrode E1and the second electrode E2, so that the refractive index distribution of the area corresponding to the unit-electrode U2is improved, and the image quality of the liquid crystal element100is improved by improving the distribution. As shown inFIG.1B, in the liquid crystal element100, unit-electrodes have various widths and are arranged in radial and circumferential directions, but when the width of the unit-electrode becomes narrow, defects such as local stagnation and the disclination of liquid crystal molecules are likely to occur. In the liquid crystal element100equipped with unit-electrodes each having a resistance layer HR, a dominant potential gradient is generated in the region AR by the first electrode E1and the second electrode E2, but when the line width of the auxiliary electrode EC is larger than the line width of the first electrode E1or the second electrode E2, there is a high possibility that the potential gradient of the region AR will be adversely affected. However, by extending the auxiliary electrode EC within the area AR with the line width that is less than or equal to the line width of the first electrode E1and the second electrode E2, it is possible to improve the refractive index distribution in the area corresponding to the unit-electrode U2while keeping the influence on the potential gradient in the liquid crystal layer LC. Moreover, since the thickness of the liquid crystal layer LC is 5 μm or more and 30 μm or less, even if the line width of the auxiliary electrode EC is the same as that of the first electrode E1or smaller than the first electrode E1etc., it is thought that it contributes to improving the refractive index distribution.

Further, in the liquid crystal element100of the present embodiment, the unit-electrode U2with the auxiliary electrode EC is arranged when the width of the region AR is 200 μm or less, and the unit-electrode U1without the auxiliary electrode is arranged when the line width of the region AR is larger than 200 μm.

As shown inFIG.1B, a unit-electrode U1is arranged on the center side (closer to the optical axis) of the liquid crystal element100, and a unit-electrode U2is arranged on the outer periphery side (farther from the optical axis) of the liquid crystal element100, but in the following the unit-electrode U2and the auxiliary electrode EC will be explained in more detail below usingFIG.5.

As shown inFIG.5, the unit-electrode U2has an auxiliary electrode EC in a region AR between the first electrode E1and the second electrode E2. The line width of the auxiliary electrode EC may be narrower than the line width of the first electrode E1and the second electrode E2, and may be ¾ of the line width of the first electrode E1and the second electrode E2, and may be ⅔ or less, ½ or less, or ⅓ or less.

Further, the auxiliary electrode EC may be formed with a specific line width of 12 μm or less, 8 μm or less, or 6 μm or less. In addition, the auxiliary electrode EC may be composed of a colored metal film (for example, copper or aluminum) that has higher conductivity than a transparent conductive film such as ITO, whereby the line width can be made thinner.

Further, the first voltage V1and the second voltage V2are supplied to the first electrode E1and the second electrode E2, as in the case of the unit-electrode U1. The first voltage V1and the second voltage V2are different voltages in order to generate a potential gradient in the region AR, but as the width of the region AR becomes narrower to 120 μm or less, or 90 μm or less, or 60 μm or less, it is thought that the behavior of liquid crystal molecules is more likely to be influenced by factors that are difficult to predict, and it becomes difficult to obtain a refractive index distribution that corresponds to the width size of the unit-electrode gradient. However, in this embodiment, the controllability of the behavior of liquid crystal molecules in the region AR is improved by arranging the auxiliary electrode EC with the line width as described above in the unit-electrode U2, thereby improving the refractive index distribution.

In addition, the liquid crystal molecules are indicated by the solid line shown in the liquid crystal layer LC inFIG.5. This figure shows an example of the expected behavior of liquid crystal molecules, when a voltage with an effective value of 0.5V as the first voltage to the first electrode, 2.0V as the second voltage to the second electrode, and 1.0V as the auxiliary voltage to the auxiliary electrode is applied. Further, the auxiliary voltage V3of this embodiment is a rectangular wave voltage having the same frequency and phase as the first voltage V1and the like. Furthermore, the liquid crystal molecules indicated by the broken line shows an example of expected behavior of liquid crystal molecules when the same voltage as above is applied to the first electrode E1and the second electrode E2in a state where the auxiliary electrode EC is not present (or a state where no voltage is applied to the auxiliary electrode EC).

If the auxiliary electrode EC is not present, as shown inFIG.5by the broken line, liquid crystal molecules are expected to occur relatively widely in the place, where the liquid crystal molecules on the first electrode E1side, which is the low potential side, will not rise enough and the refractive index gradient will be insufficient. On the other hand, when a voltage is applied to the auxiliary electrode EC, as shown by the solid line liquid crystal molecules, the liquid crystal layer LC is driven so that the liquid crystal molecules gradually rise, thereby making it possible to improve the refractive index gradient within the area AR.

In addition, inFIG.5and the like, the auxiliary electrode EC is arranged closer to the first electrode E1than the second electrode E2, and the distance between the auxiliary electrode EC and the first electrode E1is narrower than the distance between the auxiliary electrode EC and the second electrode E2. When the effective value of the first voltage V1is lower than the second voltage V2, the rise of liquid crystal molecules tends to be insufficient on the side closer to the first electrode E1than the center of the area AR, and therefore, the refractive index distribution of the unit-electrode U2can be improved by supplying the auxiliary voltage V3from the auxiliary electrode EC placed along and near the first electrode E1. As for the arrangement of the auxiliary electrode EC, for example, the distance between the auxiliary electrode EC and the first electrode E1should be set to ½ or less, or ⅓ or less, or ¼ or less of the distance between the auxiliary electrode EC and the second electrode E2.

Further, when the auxiliary electrode EC is arranged along the first electrode E1as shown inFIG.5etc. the auxiliary voltage V3applied to the auxiliary electrode is set to be higher than the potential corresponding to the position of the auxiliary electrode EC when it is thought that a linearly transitioning potential gradient is occurring between the first electrode E1and the second electrode E2. Specifically, when the distance between the center of the auxiliary electrode EC and the first electrode E1is P1, and the distance between the center of the auxiliary electrode EC and the second electrode E2is P2, the effective value V1E of the first voltage V1, the effective value V2E of the second voltage V2, and the effective value V3E of the auxiliary voltage V3are set so as to satisfy the following equation (1).

V⁢3E>(V⁢2E-V⁢1E)×P⁢1P⁢1+P⁢2+V⁢1E(1)

By setting the auxiliary voltage V3as described above, it is possible to improve the refractive index distribution of the unit-electrode U2by making it easier for molecules stagnant on the side near the first electrode E1, which is the low potential side, to stand up. Further, the effective value of the auxiliary voltage V3may be set to be, for example, 1.1 times or more than 1.2 times the right side of the above equation.

Further, as the auxiliary voltage V3is applied to the auxiliary electrode EC, for example, it is preferable to apply a voltage having an effective value equal to or higher than the threshold voltage of the liquid crystal material included in the liquid crystal layer LC. By applying a voltage higher than the threshold voltage to the auxiliary electrode EC having a narrow line width, the liquid crystal molecules are locally driven (or easily driven) in the area AR, and the refractive index gradient at the unit-electrode U2can be improved by improving the behavior of the liquid crystal molecules in the portions where they were stagnant due to insufficient rise. In addition, the effective value V1E in the above equation (1) may be 0V or a value larger than 0V. Furthermore, by setting the effective value of the first voltage V1, which is on the low potential side, to a value greater than 0V and lower than the threshold voltage, it is possible to easily generate a refractive index gradient in the region close to the first electrode E1, however the present invention is not limited to this embodiment.

The threshold voltage Vth of the liquid crystal material is expressed by the following equation (2).
Vth=π√{square root over (Keff/ε0Δε)}  (2)

K33 (bend elastic constant) is used for Keff, ε0 is the dielectric constant in a vacuum, and Δε is the dielectric anisotropy. Furthermore, 5 CB is used as the liquid crystal material filled in the liquid crystal layer LC of the liquid crystal element100of this embodiment. The threshold voltage of 5 CB can be determined by using the specification values for K33 and Δε, and is 0.934V.

Further, as the auxiliary electrode EC, an auxiliary voltage V3may be applied so that a vertical electric field is applied to the liquid crystal material included in the liquid crystal layer LC so that the effective value is higher than the voltage at which the retardation value starts to change. The voltage at which such a change in retardation value begins can be measured in the process of increasing the voltage between the flat electrodes, in a state sandwiching the liquid crystal material between two substrates on which planar electrodes are formed, and while maintaining room temperature (20° C.) conditions.

The retardation value can be measured using a micro area polarization analyzer (OPTIPRO micro) manufactured by SHINTECH, and the wavelength when measuring the retardation value is 550 nm and the spot diameter is φ3 μm. In addition that retardation (phase delay) is expressed as Δn×d. The symbol Δn is the refractive index anisotropy of the liquid crystal layer LC, and the symbol d corresponds to the thickness of the liquid crystal layer LC. It is also possible to calculate the refractive index gradient (spatial gradient of retardation) in a unit-electrode in a similar manner. In addition, the liquid crystal element100of this embodiment may be one in which the polarity of the Fresnel lens, such as a convex type or a concave type, is fixed so that, for example, the voltage applied to the first electrode E1is always lower than the voltage applied to the second electrode E2. Furthermore, in cases where the polarity of the Fresnel lens in the liquid crystal element100is not fixed and the voltage applied to the second electrode E2is lower than the voltage applied to the first electrode E1, no voltage may be applied to the auxiliary electrode EC arranged along the first electrode E1, or the auxiliary voltage V3may be set as appropriate.

The unit-electrode U1and the unit-electrode U2have been specifically explained above. Below, the configuration of the first lead wire71and the like, the overall arrangement of the unit-electrodes U1and U2of the liquid crystal element100of this embodiment, etc. will be explained.FIG.6is a schematic cross-sectional view of a predetermined location approximately perpendicular to the extending direction of each lead wire inFIG.4, and it is a cross section, including an auxiliary electrode EC, a third lead wire73, a lead wire connection part74. Each lead wire in this embodiment is formed on the same level as the auxiliary electrode EC, etc. (formed on the glass substrate GA), and an insulating layer IL is further arranged to cover the first lead wire71and the second lead wire72. The auxiliary electrode EC is connected to a third lead wire73by straddling the second lead wire72covered with the insulating layer IL, and the auxiliary electrode EC and the third lead wire73are connected via the lead wire connection part74laminated on the insulating layer IL. These structures are also buried by an insulating layer IS1. In addition, the lead wire connection part74, the first lead wire71, the second lead wire72, and the third lead wire73are made of a transparent conductive film such as ITO, like the first electrode E1, etc., and the insulating layer IL is made of an insulating film and, like the layer IS1, it is made of silicon dioxide or the like. In addition, at the locations where each lead wire extends in the radial direction, these and the resistance layer HR are arranged so that they do not overlap, and as shown inFIG.6, an insulating layer IS2stacked between each resistance layer HR.

FIG.7shows the state of the VII-VII cross section inFIG.1B, and is a radial cross-sectional view passing near the optical axis of the liquid crystal element100. A center electrode CT including a core electrode CC is arranged at the center of the liquid crystal element100, and unit-electrodes U1and U2are arranged around the center electrode CT in succession in the radial direction. In this specification, the boundary between the center electrode CT and the unit-electrode U1is defined by the center of the insulating layer IS1interposed therebetween, and the radius Rc of the center electrode CT corresponds to the distance from the optical axis of the liquid crystal element100(center of concentric arrangement of the unit-electrode) to the boundary.

Furthermore, as shown inFIG.7, let the radius of the unit-electrodes U1and U2be Rn, where the subscript n is an integer greater than or equal to 1 and less than or equal to N, which is set in ascending order from the unit-electrode with the smallest radius to the unit-electrode with the largest radius within the plurality of unit-electrodes U1and U2, and that is assigned to each of a plurality of unit-electrodes.

For example, a numerical value such as 50 or 60 may be assigned to N, or a larger numerical value may be assigned to increase the diameter of the liquid crystal element100. Furthermore, as shown in the figure, the size of the radius of the unit-electrodes U1and U2corresponds to the distance from the optical axis of the liquid crystal element100to the boundary on the outer circumferential side (second electrode E2side) of the unit-electrodes U1and U2. In addition, for the unit-electrode U2located at the outermost circumference of the liquid crystal element100and having a radius Rn, the second electrode E2may be arranged inside the position of radius Rn with a gap similar to that of the unit-electrode U2of radius Rn−1.

The radius Rn of the unit-electrodes U1and U2of this embodiment is expressed by the following equation (3).
Rn=(n+1)1/2×RC(3)

Next, the potential distribution and retardation distribution caused in the unit-electrode will be described using simulation results for a unit-electrode having an auxiliary electrode EC and a unit-electrode not having an auxiliary electrode EC.

FIGS.8A and8Bare diagrams showing simulation results of potential distribution and retardation distribution caused in the liquid crystal layer at locations overlapping with unit-electrodes. InFIG.8AandFIG.8B, the horizontal axis identifies the coordinates indicating the position in the width direction of the unit-electrode, and the vertical axis identifies the coordinates indicating the position in the thickness direction of the liquid crystal layer (left axis) and shows the size of the retardation value (right axis). Further, the thick solid lines inFIG.8AandFIG.8Bindicate retardation values corresponding to the positions on the horizontal axis, and the thin solid lines indicate equipotential lines within the liquid crystal layer. In addition, an LCD Master 2D manufactured by SHINTECH Co., Ltd. was used for the simulation in this specification.

The conditions for the simulation inFIG.8Aare that the width of the unit-electrode is 100 μm, the width of both the first electrode E1and the second electrode E2is 20 μm, the width of the auxiliary electrode EC is 5 μm, and the thickness of the liquid crystal layer is 20 μm. Further, the distance between the first electrode E1and the second electrode E2(the width of the area AR) is 50 μm, the distance between the first electrode E1and the auxiliary electrode EC is 10 μm, and the distance between the second electrode E2and the auxiliary electrode EC is 35 μm. Further, as shown in the figure, the effective value of the first voltage V1applied to the first electrode E1is 0.5V, the effective value of the second voltage V2applied to the second electrode E2is 2.0V, and the effective value of the auxiliary voltage V3applied to the electrode EC is 1.0V. Further, inFIG.8A, the lower limit value of the retardation value (right axis) is 0 nm and the upper limit value is 5010 nm, and the same holds true for the subsequent diagrams showing the simulation results.

FIG.8Bdiffers from the simulation conditions inFIG.8Ain that it does not have the auxiliary electrode EC, but other conditions (width of the unit-electrode, thickness of the liquid crystal layer, width of the region AR, width or applied voltage of the first electrode E1and the second electrode E2) are the same as the simulation conditions inFIG.8A.

First, regarding the potential distribution, inFIG.8B, the equipotential lines near the substrate where the first electrode E1etc. are formed (the upper position in the figure) becomes denser toward the second electrode E2side and sparse toward the first electrode E1side, whereas inFIG.8A, the sparseness of the equipotential lines is relaxed due to the presence of the auxiliary electrode EC. More specifically, inFIG.8A, there are three equipotential lines between the first electrode E1and the auxiliary electrode EC, but inFIG.8B, there is only about one equipotential line at the corresponding location.

Next, regarding the retardation distribution, inFIG.8B, the slope near the first electrode E1is poor and the change in retardation value is small, but inFIG.8A, since the potential distribution has been improved, the magnitude of the slope is maintained to some extent even near the first electrode E1, and the slope of the retardation value is improved.

In a unit-electrode with a retardation curve as shown inFIG.8B, light is scattered near the first electrode E1of the unit-electrode, which deteriorates the light collection performance of the divergence performance and causes optical aberration and the like, which deteriorates the image quality of the liquid crystal element100as a Fresnel lens, however, by arranging the auxiliary electrode EC to form a unit-electrode with a retardation curve as shown inFIG.8A, the image quality of the liquid crystal element100is improved.

Furthermore, as shown inFIG.1Band equation (3), the width of the unit-electrode gradually decreases as it approaches the outer periphery of the liquid crystal element100.

As the width of the unit-electrode becomes smaller, not only the effects caused by the physical characteristics of the liquid crystal material begin to become apparent, but also the effects of manufacturing constraints such as minimum design dimensions become apparent, making it difficult to control the refractive index gradient. As shown and explained inFIG.8AandFIG.8B, a potential distribution occurs in the liquid crystal layer LC, but a slight distortion in the equipotential lines may cause disclination, and as the width of the unit-electrode decreases, unexpected defects are more likely occur. Therefore, in the liquid crystal element100according to the present embodiment, by changing the position where the auxiliary electrode EC is arranged in the plurality of unit-electrodes U2having different widths, the image quality can be improved by making defects such as stagnation and disclination of the liquid crystal molecules less likely to occur in each of the plurality of unit-electrodes U2. In other words, the auxiliary electrode EC suppresses the occurrence of the previous defects, thereby improving the image quality. Specifically, in a plurality of unit-electrodes U2having different widths of the region AR, by appropriately changing the ratio of P1and P2(ratio of distance P1from the first electrode E1to the center of the auxiliary electrode EC to distance P2from the second electrode E2to the center of the auxiliary electrode EC) inFIG.5and arranging them, distortion is less likely to occur in the equipotential lines.

Furthermore, in the liquid crystal element100of this embodiment, the image quality may be improved by changing the width of the auxiliary electrode in the plurality of unit-electrodes U2having different widths of the regions AR. The liquid crystal element100in this case may include a unit-electrode U2having an auxiliary electrode formed of a transparent conductive film, and a unit-electrode U2having an auxiliary electrode formed of a colored metal film. Colored metal films such as copper and aluminum have higher conductivity than transparent conductive films such as ITO, therefore design constraints such as minimum design dimensions are relaxed, and the line width of the auxiliary electrode formed of a colored metal film can be made thinner, and the line width can also be made smaller than 5 μm or even less than 5 μm. Therefore, for example, when the width of the area AR is less than or equal to a predetermined value, the auxiliary electrode may be formed using a colored metal film, and when the width is larger than the predetermined value, the auxiliary electrode may be formed using a transparent conductive film, and the width of the area AR of the unit-electrode U2having the auxiliary electrode formed of a colored metal film may be narrower than the width of the area AR of the unit-electrode U2having the auxiliary electrode formed of a transparent conductive film.

Second Embodiment

Next, a liquid crystal element100according to a second embodiment of the present invention will be described. The liquid crystal element100in the second embodiment includes a plurality of unit-electrodes U1and U2, similar to the schematic configuration shown inFIG.1B, but a plurality of auxiliary electrodes are arranged in the unit-electrode U2.

FIG.9is a partially enlarged schematic plan view for explaining the planar configuration of the unit-electrode U2provided with the auxiliary electrode in the second embodiment, andFIG.10is a schematic cross-sectional view for explaining the X-X cross section inFIG.9.

FIG.9shows a planar configuration of two unit-electrodes U2adjacent in the circumferential direction. As shown in these figures, the unit-electrode U2in the second embodiment differs from the first embodiment in that it has two auxiliary electrodes (first auxiliary electrode EC1and second auxiliary electrode EC2). The liquid crystal element100of the second embodiment, with a first auxiliary electrode EC1disposed along the first electrode E1and a second auxiliary electrode EC2disposed along the second electrode E2, can improve the image quality, depending on both polarities, when functioning as a convex Fresnel lens and when functioning as a concave Fresnel lens.

The configuration of the unit-electrode U2of the liquid crystal element100of the second embodiment will be specifically described below with reference toFIG.9andFIG.10.

As shown inFIG.9, the first auxiliary electrode EC1is arranged along the first electrode E1and connected to the third lead wire73. The second auxiliary electrode EC2is arranged along the second electrode E2and connected to the fourth lead wire75. Further, the first auxiliary voltage V3is supplied from the third lead wire73to the first auxiliary electrode EC1, and the second auxiliary voltage V4is supplied from the fourth lead wire75to the second auxiliary electrode EC2. The first lead wire71is covered with an insulating layer IL, and the lead wire connecting portion76connects the second auxiliary electrode EC2and the fourth lead wire75by straddling the first lead wire71covered with the insulating layer IL. Similarly, the second lead wire72is covered with the insulating layer IL, and the lead wire connecting portion74is connected to the first auxiliary electrode EC1and the third lead wire73by straddling the second lead wire72covered with the insulating layer IL.

In addition, the third lead wire73extends in the radial direction, like the first lead wire71etc., and is connected to the first auxiliary electrode EC1of the other unit-electrode U2so that the first auxiliary electrode EC1and the third lead wire73has a comb-like structure. The fourth lead wire75also extends in the radial direction, like the first lead wire71etc., and is connected to the second auxiliary electrode EC2of the other unit-electrode U2, so that the second auxiliary electrode EC2and the fourth lead wire75has a comb-like structure.

As shown inFIG.10, a first auxiliary electrode EC1and a second auxiliary electrode EC2are arranged in the area AR of the unit-electrode U2.

Further, the distance between the center of the first auxiliary electrode EC1and the first electrode E1is P1, the distance between the center of the first auxiliary electrode EC1and the second electrode E2is P2, the distance between the center of the second auxiliary electrode EC2and the second electrode E2is P3, and the distance between the center of the second auxiliary electrode EC2and the first electrode E1is P4. The first auxiliary electrode EC1and the second auxiliary electrode EC2are preferably arranged substantially symmetrically as a standard the center of the area AR.

Further, the effective value of the first voltage V1applied to the first electrode E1is V1E, the effective value of the second voltage V2applied to the second electrode E2is V2E, and the effective value of the first auxiliary voltage V3applied to the first auxiliary electrode EC1is V3E, and the effective value of the second auxiliary voltage V4applied to the second auxiliary electrode EC2is V4E, and when V2E>V1E, the effective value V3E of the voltage applied to the first auxiliary electrode EC1is set to satisfy the above equation (1) (or set to be higher than the threshold voltage). In addition, when V1E>V2E, the effective value V4E of the voltage applied to the second auxiliary electrode EC2is determined by using the above formula (1), P1is replaced by P3, P2is replaced by P4, V3E is replaced by V4E, V2E is replaced by V1E, and V1E is replaced by V2E (or set to be equal to or higher than a threshold voltage).

As described above, by setting the effective value of the voltage applied to the first auxiliary electrode EC1and the second auxiliary electrode EC2, local stagnation of liquid crystal molecules can be improved in both convex and concave polarities. In addition, if the first voltage V1has a lower effective value than the second voltage V2, the voltage applied to the second auxiliary electrode EC2may be set appropriately, or no voltage may be applied. Similarly, if the voltage of the second voltage V2has a lower effective value than the first voltage V1, the voltage applied to the first auxiliary electrode EC1may be set appropriately, or no voltage may be applied.

FIG.11is a diagram showing simulation results of potential distribution and retardation distribution caused in the liquid crystal layer at a location overlapping with the unit-electrode U2having two auxiliary electrodes. The vertical and horizontal axes inFIG.11are the same as inFIG.8A, etc., and the thick solid line indicates the retardation value corresponding to the position on the horizontal axis, and the thin solid line indicates the equipotential line in the liquid crystal layer.

The simulation conditions inFIG.11are that the width of the unit-electrode is 100 μm, the width of each of the first electrode E1and the second electrode E2is 20 μm, the width of each of the first auxiliary electrode EC1and the second auxiliary electrode EC2is 5 μm, and the thickness of the liquid crystal layer is 20 μm. Further, the distance between the first electrode E1and the second electrode E2(the width of the area AR) is 50 μm, the distance between the first electrode E1and the first auxiliary electrode EC1is 10 μm, the distance between the second electrode E2and the second auxiliary electrode EC2is 10 μm, and the distance between the first auxiliary electrode EC1and the second auxiliary electrode EC2is 20 μm. Further, as shown in the figure, the effective value of the first voltage V1applied to the first electrode E1is 0.5V, the effective value of the second voltage V2applied to the second electrode E2is 2.0V, the effective value of the auxiliary voltage V3applied to the first auxiliary electrode EC1is 1.0V, and the effective value of the auxiliary voltage V4applied to the second auxiliary electrode EC2is 1.625V.

In addition, the voltages inFIG.11can be reversed horizontally on the graph of the retardation value, by setting the effective value of the first voltage V1applied to the first electrode E1to 2.0V, setting the effective value of the second voltage V2applied to the second electrode E2to 0.5V, setting the effective value of the auxiliary voltage V3applied to the electrode EC1to 1.625V, and setting the effective value of the auxiliary voltage V4applied to the second auxiliary electrode EC2to 1.0V. Thereby, the polarity of the liquid crystal element100functioning as a Fresnel lens can be reversed from convex to concave.

As described above, in the liquid crystal element100according to the second embodiment, the unit-electrode U2including two auxiliary electrodes (first auxiliary electrode EC1, second auxiliary electrode EC2) is arranged in an arc shape, and thereby, image quality can be improved in response to both convex and concave polarities. The liquid crystal element100according to the second embodiment is almost the same as the liquid crystal element100according to the first embodiment except for these points, and a description of this similar point will be omitted.

Third Embodiment

Next, a liquid crystal element100according to a third embodiment of the present invention will be described. The liquid crystal element100according to the third embodiment is composed of the unit-electrode U1where no auxiliary electrode is placed, the unit-electrode U2where one auxiliary electrode is placed (seeFIG.5), and the unit-electrode U2where two auxiliary electrodes are placed (seeFIG.10), and this is the main difference from the liquid crystal element100according to the first embodiment.

In the liquid crystal element100according to the third embodiment, an area where a unit-electrode U1having no auxiliary electrode is arranged, an area where a unit-electrode U2having two auxiliary electrodes is arranged, and an area where a unit-electrode U2having only one auxiliary electrode is arranged, are provided in order from the optical axis LA. In other words, first, as inFIG.1B, a unit-electrode U1having no auxiliary electrodes is arranged around the central center electrode CT, and a unit-electrode U2having two auxiliary electrodes is arranged in an annular region (first annular region) outside of the unit-electrode U1, and a unit-electrode U2having only one auxiliary electrode is further arranged in an annular region outside the first annular region (second annular region). In the liquid crystal element100according to the third embodiment, as shown inFIG.1Band equation (3), since the width of the unit-electrode gradually decreases as it approaches the outer periphery, there is insufficient space for arranging the auxiliary electrode, so this structure is adopted.

Further, the width of the region AR in the unit-electrode U2where only one auxiliary electrode EC is arranged is narrower than the width of the region AR in the unit-electrode U2where two auxiliary electrodes are arranged.

As the unit-electrode U2has only one auxiliary electrode EC, it is preferable to arrange the auxiliary electrode EC at a position approximately at the center of the area AR (or at a position where the distance is ⅘ or more of the distance between the second electrode E2and the auxiliary electrode EC, and the distance between the second electrode E2and the auxiliary electrode EC is ⅘ or more of the distance between the first electrode E1and the auxiliary electrode EC), for example. With this arrangement, it is possible to increase the aperture while improving the image quality of the liquid crystal element100in response to both convex and concave polarities. In addition, in at least some of the unit-electrodes U2arranged in the second annular region, the auxiliary electrodes EC may be made of a colored metal film.

Further, the voltage input to the auxiliary electrode EC of the unit-electrode U2in the second annular region, a voltage with the same effective value as the auxiliary electrode placed on the side closer to the lower potential side of the first electrode Eland the second electrode E2in the unit-electrode U2in the first annular region, may be applied, and alternatively, a voltage different from the voltage applied to the two auxiliary electrodes in the unit-electrode U2of the first annular region may be applied. Further, it is preferable that the auxiliary electrode EC of the unit-electrode U2in the second annular region be connected to a lead wire different from the lead wire connected to the first auxiliary electrode EC1and the second auxiliary electrode EC2in the unit-electrode U2in the first annular region.

The liquid crystal element100according to the third embodiment is substantially the same as the liquid crystal element100according to the first embodiment except for the points mentioned above, and a description of the similar points will be omitted.

Fourth Embodiment

Next, a liquid crystal element100according to a fourth embodiment of the present invention will be described. In the liquid crystal element100according to the fourth embodiment, the plurality of unit-electrodes in the liquid crystal element100is divided into several different unit-electrode groups, and includes a plurality of combinations of lead wires for input to the first electrode E1and lead wires for input to the second electrode E2so that inputs to different groups can be individually controlled.

FIG.12Ais a schematic plan view for explaining the schematic configuration of the liquid crystal element100in the fourth embodiment, and some of the configurations are omitted for convenience. As shown in the figure, the liquid crystal element100has a plurality of common input sections CP1, CP2, and CP3, and each of the common input sections corresponds to an area whose distance from the optical axis is within a predetermined range, and are arranged accordingly. Further, the plurality of arc-shaped unit-electrodes arranged concentrically in the liquid crystal element100belong to one of the common input sections, and each common input section is configured to include a group of unit-electrodes that have a common input to the first electrode E1and a common input to the second electrode E2.

Further, the common input sections CP1, CP2, and CP3are arranged in order closest from the optical axis LA of the liquid crystal element100, and the common input section CP1corresponds to a fan-shaped area with a predetermined radius centered on the optical axis LA, the common input section CP2corresponds to an arc-shaped area adjacent to and outside the common input section CP1, and the common input section CP3corresponds to an arc-shaped area adjacent to and outside the common input section CP2. The common input sections CP1, CP2, and CP3correspond to regions having thickness in the radial direction of a circle centered on the optical axis LA of the liquid crystal element100.

Moreover, the comb-teeth structure81inFIG.12Ais configured in a comb-tooth shape by a first electrode E1group of a plurality of unit-electrodes belonging to the common input section CP1and a lead wire connected to the first electrode E1group. Similarly, the comb-tooth structure82is configured in a comb-tooth shape by the second electrodes E2group of the plurality of unit-electrodes belonging to the common input section CP1and a lead wire connected to the second electrodes E2group. Similarly, the comb-tooth structure83and the comb-tooth structure85are also configured in a comb-tooth shape by the first electrode E1group of unit-electrodes belonging to the common input section CP2and the common input section CP3and the lead wires connected to these, and the comb-tooth structure84and the comb-tooth structure86are also configured in a comb-tooth shape by the second electrode E2group of unit-electrodes belonging to the common input section CP2and the common input section CP3and the lead wires connected thereto. The comb-tooth structures81to86are comb-tooth structures in which the lead wire is the trunk and the first electrode E1and the second electrode E2are the branches, but inFIG.12A, the first electrode E1and the second electrode E2are omitted, and only a part of the first electrode E1group and the second electrode E2group included in the comb-tooth structures81to86are shown.

Further, as shown inFIG.12A, the common input sections CP1, CP2, and CP3in the fourth embodiment correspond to areas where the liquid crystal element100is divided into four areas with a central angle of 90 degrees. In each of the four divided areas of the liquid crystal element100, comb-tooth structures81to86are similarly arranged, and different inputs are input from a control section (not shown) of the liquid crystal element100to the common input sections CP1, CP2, and CP3.

In addition, it is preferable that the input to the common input sections CP1, CP2, and CP3be the same in each of the four divided areas, but this is not necessarily limited.

In addition, as for the input to the plurality of common input sections of the liquid crystal element100, it is preferable that the voltage applied to the liquid crystal layer from both ends of the area AR of the unit-electrode becomes a high frequency as the position becomes farther from the optical axis LA. In the liquid crystal element100, the width of the unit-electrode and the width of the area AR become narrower as the distance becomes farther from the optical axis LA and approaches the outer periphery of the liquid crystal element100, however, for the unit-electrodes with narrow unit-electrode widths or area widths, the refractive index gradient tends to be easier to improve when the input voltage to the first electrode E1and the second electrode E2is set to a high frequency. Therefore, by the input to the unit-electrode group belonging to the common input section disposed on the outside being controlled to a higher frequency than the input to the unit-electrode group belonging to the common input section disposed on the inner side (the input to the first electrode E1group of the outer common input section is higher frequency than the input to the first electrode group of the inner common input section, and the input to the second electrode E2group of the outer common input section is higher frequency than the input to the second electrode E2, or input to the electrode group to which the voltage with the larger effective value is input between the first electrode E1group and second electrode group E2is made to have a higher frequency at the outer common input section than at the inner common input section), the image quality of the liquid crystal element100can be improved.

Furthermore, as for the input to the plurality of common input sections of the liquid crystal element100, it is preferable that the voltage difference applied to the liquid crystal layer from both ends of the area AR of the unit-electrode increases as the position becomes farther from the optical axis LA. Specifically, the difference between the effective values of the input voltages from the first electrode group and the second electrode group is larger at the outer common input section than at the inner common input section. In the liquid crystal element100, the width of the unit-electrode and the width of the area AR tend to become narrower as the distance from the optical axis LA approaches the outer periphery of the liquid crystal element100, and as the width becomes narrower, it becomes difficult to achieve the desired refractive index gradient. As described above, by making the difference in the effective value of the input voltage to both ends of the area AR of the unit-electrode group different between the inner common input section and the outer common input section, the focal length of the inner common input section and the focal length of the outer common input section can be easily matched, and thereby the image quality of the liquid crystal element100can be improved. In addition, the image quality of the liquid crystal element100can be further improved by configuring it to the plurality of common input sections, and the voltage applied to the liquid crystal layer from both ends of the area AR of the unit-electrode (or one end on the high potential side) becomes higher in frequency as the position becomes farther from the optical axis LA, and increasing the difference in the effective value of the input voltage applied to both ends of the area AR.

Further, in the liquid crystal element100of the fourth embodiment, the unit-electrode U2(seeFIG.5) including the auxiliary electrode EC is arranged when the width of the region AR is 200 μm or less, as in the first embodiment, and when the width of the region AR becomes larger than 200 μm, a unit-electrode U1without an auxiliary electrode EC is arranged. Specifically, in the common input section CP1, the unit-electrode group is composed of only the unit-electrode U1without the auxiliary electrode EC, and in the common input section CP2, the unit-electrode group is composed of the unit-electrode U1without the auxiliary electrode EC and the unit-electrode U2with the auxiliary electrode EC, and in the common input section CP3, the unit-electrode group is composed of only the unit-electrode U2with an auxiliary electrode EC.

Further, in the liquid crystal element100of the fourth embodiment, unit-electrodes U1without auxiliary electrodes EC and unit-electrodes U2with auxiliary electrodes EC may be arranged in a mixed manner in each of the plurality of common input sections. Alternatively, the unit-electrode group in each of the plurality of common input sections may be composed of only the unit-electrode U2having the auxiliary electrode EC. Further, the unit-electrode group in each of the plurality of common input sections may be composed only of the unit-electrode U1without the auxiliary electrode EC, and even in such a case, the image quality of the liquid crystal element100can be improved by allowing inputs to the plurality of unit-electrodes in the liquid crystal element100to be made in a plurality of modes.

Further, the configuration of the unit-electrode U2in the liquid crystal element100of the fourth embodiment may be a unit-electrode U2provided with two auxiliary electrodes (a first auxiliary electrode EC1and a second auxiliary electrode EC2), or a unit-electrode U2provided with only one auxiliary electrode EC. Furthermore, the unit-electrode group in each of the plurality of common input sections may be composed of only the unit-electrode U2with two auxiliary electrodes, or the unit-electrode U1without the auxiliary electrode EC, the unit-electrode U2with only one auxiliary electrode EC, and the unit-electrode U2with two auxiliary electrodes may be arranged in a mixed manner. In addition, when they are arranged in a mixed manner, it is preferable that the width of the area AR of the unit-electrode U2having only one auxiliary electrode EC is narrower than the width of the area AR of the unit-electrode U2having two auxiliary electrodes, and the former unit-electrode U2having only one auxiliary electrode EC may be arranged approximately at the center of the area AR.

Further, in the liquid crystal element100of the fourth embodiment, when the unit-electrode U2having only one auxiliary electrode EC is included, for each common input section, the input to the auxiliary electrode EC group of the unit-electrode U2is configured to be common, and when the unit-electrode U2having two auxiliary electrodes EC (the first auxiliary electrode EC1and the second auxiliary electrode EC2) is included, each common input section is configured so that the inputs of the unit-electrode U2to the auxiliary electrode EC1group are common, and the inputs of the unit-electrode U2to the second auxiliary electrode EC2group are common. Also, regarding the inputs to the auxiliary electrode EC group, the first auxiliary electrode EC1group, and the second auxiliary electrode EC2group of the common input section, the common input section disposed on the outside is made to be a high-frequency input compared to the input to the common input section disposed on the inside.

Specifically, when a plurality of unit-electrodes U2having only one auxiliary electrode EC is included in the common input part CP2, a comb-teeth structure constituted by the auxiliary electrode EC group of the unit-electrode U2belonging to the common input part CP2and lead wires connected to the auxiliary electrode EC group is arranged separately from a comb-teeth structure83constituted by the first electrode E1group and the lead wires and a comb-teeth structure84constituted by the second electrode E2group and the lead wires. Similarly, when a plurality of unit-electrodes U2having two auxiliary electrodes (a first auxiliary electrode EC1and a second auxiliary electrode EC2) are included in the common input section CP2, the comb-tooth structure constituted by the lead wires connected to the second auxiliary electrode EC1group and a comb-tooth structure constituted by the lead wires connected to the second auxiliary electrode EC2group are arranged separately from the comb-tooth structure83and the comb-tooth structure84. Therefore, when the unit-electrode U2having only one auxiliary electrode and the unit-electrode U2having two auxiliary electrodes are mixed in the common input section CP2, there are five types of lead wires that are input to the common input section CP2.

The liquid crystal element100according to the fourth embodiment is almost the same as the liquid crystal element100according to the first embodiment except that it has the configuration of a plurality of common input sections as described above, and a description of the similar points will be omitted.

Modification of the Fourth Embodiment

Next, a liquid crystal element100according to a modification of the fourth embodiment will be described. In the fourth embodiment described above, the width of the unit-electrode becomes narrower depending on the distance from the optical axis LA of the liquid crystal element100, as shown in equation (3), etc., however in this modified example, there is a portion where the width of the unit-electrode locally increases even when away from the optical axis LA.

FIG.12Bis a schematic plan view for explaining the schematic configuration of the liquid crystal element100in a modification of the fourth embodiment, and for convenience, some of the configurations are omitted and a plurality of common input sections CP1, CP2, and CP3corresponding to a quarter of the liquid crystal element100are shown.

The liquid crystal element100according to the modification of the fourth embodiment has a plurality of common input sections CP1, CP2, and CP3as in the case ofFIG.12A, and in each area to which these input sections correspond, as shown inFIG.12B, the unit-electrode group is disposed such that the width of the unit-electrode becomes narrower as it moves away from the optical axis LA. Further, in the liquid crystal element100according to the present modification, the width of the unit-electrode located closest to the optical axis LA of the common input section CP2(unit-electrode disposed at the innermost circumference) is larger than the width of the unit-electrode located at the farthest position from the optical axis LA (the unit-electrode disposed at the outermost circumference). Further, the width of the unit-electrode disposed at the position closest to the optical axis LA of the common input section CP3is larger than the width of the unit-electrode disposed at the position furthest from the optical axis LA of the common input section CP2.

Therefore, in the liquid crystal element100of this modification, in two adjacent common input sections, the width of the unit-electrode disposed at the innermost periphery of the common input section disposed on the far side from the optical axis LA (or the width of several unit-electrodes arranged in series from the innermost circumference to the side away from the optical axis LA) is wider than the width of the unit-electrode disposed at the outermost periphery of the common input section disposed on the nearer side from the optical axis LA (or the width of several unit-electrodes arranged in series from the outermost circumference to the side closer to the optical axis LA). In the liquid crystal element100of this modification, the overall width of the unit-electrode tends to become narrower as it moves away from the optical axis LA in the radial direction, but when the corresponding range of the common input section is switched, the width of the unit-electrode becomes wider without following this trend.

From another point of view, in each of two adjacent common input sections, a narrower unit-electrode is disposed in a portion farther from the optical axis LA (a portion on the outer periphery side) than a portion closer to the optical axis LA (a portion on the optical axis side or an inner periphery side), that is, the arrangement density (arrangement density per unit length in the radial direction) of unit-electrodes in the inner circumference side portion of the common input section disposed on the side far from the optical axis LA is less than on the outer circumference side portion of the common input section disposed on the side close to the optical axis LA. That is, in the liquid crystal element100of this modification, at the boundary between two adjacent common input sections, sparseness and denseness occur in the arrangement density of the unit-electrodes, and portions where the arrangement density is sparse (portion at the optical axis side or inner peripheral side of the common input section) and portions where the arrangement density is dense (portion on the outer circumferential side of the common input section) are alternately arranged.

In addition, in the liquid crystal element100of this modification, as in the case of the liquid crystal element100of the fourth embodiment described above, as the plurality of common input sections are arranged on the outside, the input to the unit-electrode group belonging to the common input section is made to have a high frequency (for example, as the plurality of common input sections are arranged on the outer side, the input on the high potential side of the first electrode group and the second electrode group are made to have a high frequency).

Further, as in the fourth embodiment described above, the difference in the effective value of the input voltage from the first electrode group and the second electrode group is made larger at the outer common input section than at the inner common input section. Therefore, among the three common input sections, the difference in the input frequency and effective value of the input voltage to the common input section CP3is the largest, and the difference in the input frequency etc. to the common input section CP1is the smallest. The image quality of the liquid crystal element100can be improved by doing the following: setting the input frequency, etc. to the unit-electrode group (the first electrode group, the second electrode group, and the auxiliary electrode group in the unit-electrode group) in each common input section to make it easier to improve the refraction index gradient of the outer circumference side of the common input section, and adjusting the width of the unit-electrode on the inner circumferential side as shown inFIG.12Bto match this input frequency etc. (adjust so that the arrangement density is sparse).

Further, in the liquid crystal element100of this modification, as shown inFIG.12B, a unit-electrode U1having no auxiliary electrode and a unit-electrode U2having one or two auxiliary electrodes are arranged.

Although the liquid crystal element100of the modification of the fourth embodiment has been described above, the points not explained are substantially the same as the liquid crystal element100of the fourth embodiment, and explanations of the points that are substantially the same will be omitted.

In addition, in the fourth embodiment and its modifications, it is desirable that the frequencies of the input voltages to the first electrode E1group, the second electrode E2group, and the auxiliary electrode group be the same in the unit-electrode groups in each of the common input sections, however it is not necessarily limited to these embodiments.

Further, in the fourth embodiment and the like, the circumferential direction of the liquid crystal element100is divided into four, and further the common input section is provided, and divided into three parts according to the distance from the optical axis LA, but the common input section is not limited to this type, and it may be divided into two or more parts depending on the distance from the optical axis LA. Further, the common input section may be divided into five or more or three or less in the circumferential direction, or may be provided in a circular or annular region without being divided.

Fifth Embodiment

Next, a liquid crystal element100according to a fifth embodiment of the present invention will be described. The liquid crystal element100according to the fifth embodiment includes a plurality of unit-electrodes U1and U2like the first embodiment shown inFIG.1B, but the main difference from the liquid crystal element100of the first embodiment is that it has a transmitted light restriction section that blocks at least a portion of transmitted light in an area different from the area AR.

FIG.13is a schematic cross-sectional view showing a radial cross section passing near the optical axis of a liquid crystal element100according to a fifth embodiment of the present invention, and corresponds to the position of the VII-VII cross section inFIG.1B.

As shown inFIG.13, equation (3), etc., as in the case of the first embodiment, the liquid crystal element100of the fifth embodiment is configured to include a plurality of unit-electrodes in which the width of the unit-electrode U1and U2becomes narrower as the distance from the optical axis LA of the liquid crystal element100increases. Further, the transmitted light restricting section of the fifth embodiment includes a shielding layer BM and an insulating layer IS3, and after the transmitted light restricting section is laminated on a glass substrate GA (not shown), the structure of the first electrode E1, resistance layer HR, etc., are sequentially laminated. In addition, the transmitted light restricting section may be constituted by an independent member different from the transparent substrate B1and the transparent substrate B2, or may be formed on a different substrate from the glass substrate on which the first electrode E1and the like are formed, and may be arranged on either side of the liquid crystal layer LC.

The shielding layer BM is composed of, for example, a laminated film of metallic chromium or chromium oxide, but may also be composed of a low-reflection light-shielding resin. The insulating layer IS3is made of silicon dioxide, for example, and is laminated so as to bury the shielding layer BM. In addition, the shielding layer BM of the transmitted light restricting section may be configured so that a part of the transmitted light is shielded by a semi-transparent material, and the transmitted light through the boundary portion where the shielding layer BM is arranged is suppressed more than the transmitted light through the area AR.

Further, the shielding layer BM is arranged at the boundary between two adjacent unit-electrodes, as shown inFIG.13. As shown in the figure, the shielding layer BM is arranged so as to overlap the insulating layer IS1interposed between the two unit-electrodes, and also it extends so as to overlap at least a portion of the first electrode E1and at least a portion of the second electrode E2.

By arranging such a shielding layer BM, a refractive index gradient occurs in the opposite direction to the refractive index gradient that occurs dominantly in the area AR, reducing the transmitted light in the portion where the refractive index changes sharply, and thereby the image quality of the liquid crystal element100can be improved.

Further, the transmitted light restricting portion of this embodiment is configured by, for example, arranging a shielding layer BM at the boundary between unit-electrodes where the width of the area AR is 200 μm or less. As shown inFIG.13, equation (3), etc., when the width of the unit-electrode becomes narrower depending on the distance from the optical axis LA of the liquid crystal element100, by arranging the width of the unit-electrode so that the ratio of the width of the shielding layer BM to the total width of the two unit-electrodes that the shielding layer BM spans gradually increases as it moves away from the optical axis LA of the liquid crystal element100, the image quality can be improved when the aperture is increased. In other words, by arranging them so that (the width of the shielding layer BM)/(the total value of the widths of the two unit-electrodes that the shielding layer BM straddles) gradually increases as the distance from the optical axis LA of the liquid crystal element100increases, the image quality can be improved when increasing aperture.

Further, the shielding layer BM is arranged at the boundary between two unit-electrodes when the width of the two unit-electrodes adjacent to each other is less than a predetermined value, and if the width of one of the two unit-electrodes adjacent to each other is larger than the predetermined value, it may not be arranged. This ensures brightness in the area close to the optical axis LA of the liquid crystal element100, and improves image quality in the area far from the optical axis LA.

FIG.14AandFIG.14Bare diagrams showing simulation results of potential distribution and retardation distribution caused in the liquid crystal layer at a location overlapping with the unit-electrode U2having one auxiliary electrode EC. The vertical and horizontal axes inFIG.14AandFIG.14Bare the same as inFIG.8A, etc., and the thick solid lines are retardation values corresponding to the positions on the horizontal axis, and the thin solid lines are equipotential lines in the liquid crystal layer.

The simulation conditions inFIG.14Aare that the width of the unit-electrode U2is 100 μm, the width of each of the first electrode E1and the second electrode E2is 20 μm, the width of the auxiliary electrode EC is 5 μm, and the thickness of the liquid crystal layer is 20 μm. Further, the distance between the first electrode E1and the second electrode E2(the width of the area AR) is 50 μm, the distance between the first electrode E1and the auxiliary electrode EC is 10 μm, and the distance between the auxiliary electrode EC and the second electrode E2is 35 μm. Further, as shown in the figure, the effective value of the first voltage V1applied to the first electrode E1is 0V, the effective value of the second voltage V2applied to the second electrode E2is 2.0V, and the effective value of the auxiliary voltage V3applied to the auxiliary electrode EC is 1.0V.

FIG.14Bdiffers fromFIG.14Ain the width of the unit-electrode, and the width of the unit-electrode is 95 μm. The simulation conditions inFIG.14Bare the same as inFIG.14Aexcept for this point. That is, inFIG.14B, the width of the insulating layer IS1interposed at the boundary between adjacent unit-electrodes is narrower than in the case ofFIG.14A, and therefore a slight distortion occurs in the equipotential lines and retardation distribution of the portion overlapping with the second electrode E2. Furthermore, as shown inFIG.14AandFIG.14B, in the portion overlapping with the first electrode E1, the gradient of refractive index (gradient of retardation) that was dominant in the area AR disappears, and the gradient becomes almost zero, and in the portion overlapping with the second electrodes E2, in order to create a height difference in the refractive index gradient of the area AR, a steep refractive index gradient is generated in the opposite direction to the refractive index gradient of the region AR. Also, a portion intervening between the first electrode E1and the second electrode E2in another adjacent unit-electrode (a portion intervening between the second electrode E2and the first electrode E1in another adjacent unit-electrode), similar to the portion overlapping with the second electrode E2, generates a refractive index gradient in the opposite direction to the refractive index gradient in the area AR. Further, a portion where the refractive index gradient is almost zero, such as a portion overlapping with the first electrode E1inFIG.14AandFIG.14B, is a portion that does not contribute to image formation in the region AR because it has poor lens function. Furthermore, a portion where a refractive index gradient occurs in the opposite direction to the refractive index gradient in the region AR is also a portion that does not contribute to image formation in the region AR. By restricting the transmitted light at the boundary between two adjacent unit-electrodes, by the transmitted light limiting section of the fifth embodiment, at least a portion of the transmitted light that does not contribute to the imaging of the area AR is eliminated, so that the image quality of the liquid crystal element100becomes clearer.

By providing the transmitted light limiting section, it is possible to arrange the auxiliary electrode EC with emphasis on improvement of the refractive index distribution in the region AR while allowing deterioration of the refractive index distribution at the boundary with other unit-electrodes, and therefore, by combining the transmitted light limiting section and the auxiliary electrode EC, it is possible to further improve image quality. However, the transmitted light limiting section may be provided in a liquid crystal element constituted only by the unit-electrode U1without the auxiliary electrode EC, and even in such a case, it is expected that the image quality of the liquid crystal element will be improved.

The liquid crystal element100of the fifth embodiment is almost the same as the liquid crystal element100of the first embodiment except that it includes the transmitted light restricting section as described above, and a description of the similar points will be omitted.

Sixth Embodiment

Next, a sixth embodiment of the present invention will be described. Although the liquid crystal element100of the sixth embodiment includes a plurality of unit-electrodes U1and U2like the first embodiment shown inFIG.1B, the main difference is that an insulating wall WL is disposed at the boundary between the unit-electrodes.

FIGS.15A to15Care diagrams showing the structure of the unit-electrode U2of the sixth embodiment and simulation results of the potential distribution and retardation distribution in the liquid crystal layer, similar toFIG.8A. Further,FIG.15Dis a diagram for comparison withFIGS.15A to15C, showing simulation results of the potential distribution and retardation distribution in the liquid crystal layer in the case where the auxiliary electrode EC and the insulating wall WL are not present. The simulation conditions inFIG.15A, etc., are that the width of the unit-electrode U2is 55 μm, the width of the first electrode E1and the second electrode E2are both 10 μm, the width of the auxiliary electrode EC is 5 μm, and the thickness of the liquid crystal layer is 20 μm. Further, the width of the region AR is 30 μm, the auxiliary electrode EC is arranged in the center thereof, the first voltage V1is 0.5V, and the second voltage V2is 4.4V.

The auxiliary voltage V3inFIG.15AtoFIG.15Cis 0.8V, 1.6V, and 3.2V, respectively, and as mentioned above,FIG.15Dshows the simulation results without the insulating wall WL and auxiliary electrode EC. The insulating wall WL, which is an insulating structure, is configured so as not to shield the electric field from the first electrode E1and the second electrode E2of adjacent unit-electrodes, and has a width of 10 μm. For convenience of notation, the retardation curves are omitted for the upper left part and inside the insulating wall WL in each figure, but the retardation value in the upper left part inFIG.15AtoFIG.15Cincreases until it reaches the edge of the insulating wall WL, and becomes almost zero within the insulating wall WL. In addition, the notation of the equipotential lines is also omitted in the insulating wall WL.

As shown inFIG.15AtoFIG.15C, in the sixth embodiment, the insulating wall WL is arranged astride two adjacent unit-electrodes U2, and partially overlaps with the first electrode E1and the second electrode E2. With such structure, the insulating wall WL, which is an insulating structure, restricts the movement of the liquid crystal material, and it is thought that the controllability of the refractive index gradient by the auxiliary electrode EC is improved. In other words, the insulating wall WL improves the controllability of the refractive index gradient within the unit-electrode U2by the auxiliary electrode EC, making it easier to obtain an improved refractive index distribution.

Further, as shown inFIG.15B, when the auxiliary voltage V3is set to 1.6 V, the slope of the retardation curve becomes almost linear, which is often suitable for improving the image quality of the liquid crystal element100. In some cases, the image quality can be improved by appropriately adjusting the auxiliary voltage V3, for example, between 0.8 V and 3.2 V, and by making the slope of the retardation curve a slope with curvature.

The insulating wall WL can be formed, for example, by adding an ultraviolet curing resin into the liquid crystal material constituting the liquid crystal layer LC in advance, and irradiating the boundary portion between the unit-electrodes U1and U2with ultraviolet light after the liquid crystal material is encapsulated. Specifically, a liquid crystal material mixed with a solution of a photocurable liquid crystal monomer is sealed, and polymers are selectively precipitated and hardened by pattern exposure to ultraviolet rays. However, the insulating wall WL is not limited to this embodiment, and may be formed using other methods. Furthermore, the insulating wall WL does not need to have a height equivalent to the thickness of the liquid crystal layer and completely block the movement of the liquid crystal material, and it may have a wall-like structure with a height lower than the thickness of the liquid crystal layer.

The liquid crystal element100of the sixth embodiment is almost the same as the liquid crystal element100of the first embodiment except that it includes the wall portion WL as described above, and a description of this similar point will be omitted.

Seventh Embodiment

Next, a seventh embodiment of the present invention will be described.FIG.16is a schematic diagram for explaining the schematic configuration of a liquid crystal unit LN according to the seventh embodiment, andFIG.17is a schematic diagram for explaining the schematic configuration of eyeglasses200to which the liquid crystal unit LN according to the seventh embodiment is applied. The glasses200have a liquid crystal unit LN, so that the power can be changed.

As shown inFIG.16, the liquid crystal unit LN includes a liquid crystal element100and a liquid crystal element100A including a transmitted light restriction section RS. The liquid crystal element100A and the liquid crystal element100inFIG.16differ in the presence or absence of the transmitted light restricting part RS and the alignment direction of the alignment film of the liquid crystal layer LC, but otherwise have the same configuration. Further, the liquid crystal element100of the liquid crystal unit LN has the same configuration as the liquid crystal element100of the second embodiment, except that the liquid crystal element100A includes a transmitted light restriction section RS. Furthermore, in the liquid crystal element100A and the liquid crystal element100inFIG.16, the alignment directions of liquid crystal molecules are orthogonal to each other by the alignment film in the liquid crystal layer LC being orthogonal to each other. In addition, as the liquid crystal unit LN, two liquid crystal elements100of the first embodiment may be stacked to provide the transmitted light restricting section RS, or two liquid crystal elements100of other embodiments may be stacked to provide the transmitted light restricting section RS.

The liquid crystal elements100and100A each function as a Fresnel lens, and are arranged overlappingly so that the optical axes and the positions of the unit-electrodes coincide. The transmitted light restriction section RS restricts the light transmitted through the boundary portion of the adjacent unit-electrodes of the liquid crystal elements100and100A.

Furthermore, the transmitted light restricting section RS in the liquid crystal unit LN of the seventh embodiment is a liquid crystal module that can control the amount of transmitted light for each of a plurality of pixel regions and can function for each pixel region as an optical shutter. The transmitted light restricting section RS is configured to control the area in which transmitted light is restricted based on the voltage input to the unit-electrodes of the liquid crystal elements100and100A, and the restricted area of transmitted light may be changed depending on the polarity such as a convex shape or a concave shape, and the restricted area of transmitted light may be controlled to be increased or decreased depending on the power of the glasses200.

Glasses200inFIG.17include a pair of control sections65, a pair of liquid crystal units LN, a pair of rims301, a pair of temples303, and a bridge305. The control unit65includes a controller40and a power supply circuit41, and the controller40further includes a communication device64. A pair of rims301hold a lens having a liquid crystal unit LN. The glasses200also include an eye detection unit that acquires information regarding eye movement. The eye detection section includes an electrooculography sensor D1included in a pair of nose pads, an electrooculography sensor D2disposed on the temple part of the temple303facing the wearer, and an electrooculography sensor D2located on the upper part of the pair of rims301. Additionally, an eye detection sensor D3that detects eye movements of the wearer is included.

The electrooculography sensors D1and D2measure the electrooculography in each of the eyes to detect eye movements of the wearer. The electrodes included in the electrooculography sensors D1and D2come into contact with the skin of the wearer to detect the electrooculography at the center of the left and right eyes and at the temples. The eye detection sensor D3may include, for example, a light source such as an LED (Light Emitting Diode) and an imaging unit such as a camera. As the eye tracking technique is applied to the glasses200, for example, a non-contact type such as a corneal reflex method, a dark pupil method, or a bright pupil method may be adopted, or a contact type such as electrooculography method may be adopted, and both non-contact types and contact types may be adopted, but the types are not limited to these.

The glasses200may be configured to change the power in the liquid crystal units100A,100based on information regarding eye movements detected from the electrooculography sensors D1, D2and the eye detection sensor D3, or the transmitted light restriction area may be controlled by the transmitted light restriction section RS. Furthermore, as the eye detection section in the glasses200, an electrooculography sensor or an eye detection sensor may be placed at another location.

Although the glasses200of the seventh embodiment have been described above, the liquid crystal unit LN of the glasses200may use, for example, the liquid crystal element100of the fifth embodiment instead of the liquid crystal element100A.

In addition, although the glasses200of the seventh embodiment have the transmitted light restricting section RS, the present invention is not necessarily limited to such an aspect. Therefore, glasses may be constructed by, for example, stacking two liquid crystal elements100in any of the first to fifth embodiments. Further, the glasses equipped with the liquid crystal element100according to any of the first to fifth embodiments or the glasses200according to the sixth embodiment may be glasses having a frame structure as shown inFIG.17, or may be goggle type glasses. Furthermore, the liquid crystal element100of the first embodiment etc., may be used in XR (Extended Reality) glass type devices such as AR (Augmented Reality)/VR (Virtual Reality)/MR (Mixed Reality), or contact lenses. Furthermore, the glasses equipped with the liquid crystal element100of the first embodiment may be AR glasses, AR goggles, or smart glasses that have the function of displaying digital information superimposed on the real world, or VR goggles, VR glasses, VR headsets, or VR head-mounted displays that have the function of providing virtual reality to the user. Further, the glasses, which are these XR glasses-type devices, may have either a see-through display, a video see-through display that covers the wearer's eyes, or an immersive display.

In addition, the liquid crystal element100provided with a plurality of common input sections according to the fourth embodiment or a modification thereof may be configured to include a transmitted light restriction section RS. In addition, the transmitted light restricting section RS of the fifth embodiment is not limited to the above-described aspect, and may be arranged, for example, on the transparent substrate B2provided with the counter electrode E3, or it may be arranged at a position closer to the liquid crystal layer LC than the first electrode E1or the second electrode E2. Further, the transmitted light restricting section RS of the sixth embodiment may be arranged on the wearer's side of the glasses200or on the opposite side, and may be arranged between the two liquid crystal layers LC in the liquid crystal unit LN.

In addition, in the above-mentioned first embodiment, etc., the unit-electrodes U1and U2have an arcuate shape where the circumference is divided into four and the center angle is 90 degrees, as shown inFIG.1B, however, the present invention is not limited to such aspect. The unit-electrodes U1and U2may have an annular shape of 360 degrees or approximately 360 degrees, or may have an arc shape with a central angle of 180 degrees, 60 degrees, 45 degrees, etc. Furthermore, the liquid crystal element100may have a mixture of arcuate shapes with different center angles.

In addition, in the liquid crystal element100of the first embodiment, a unit-electrode U2including one auxiliary electrode EC is arranged, and in the liquid crystal element100of the second embodiment, a unit-electrode U2is provided with a first auxiliary electrode EC1and a second auxiliary electrode EC2is arranged, but in the liquid crystal element100, unit-electrodes U2having different numbers of auxiliary electrodes may be arranged in a mixed manner.

Further, although the auxiliary voltage input to the auxiliary electrode EC, the first auxiliary electrode EC1, and the second auxiliary electrode EC2in the first embodiment and the second embodiment is a rectangular wave voltage having the same frequency and phase as the first voltage V1and the second voltage V2, it is not necessarily limited to this aspect. Therefore, for example, the frequency of the auxiliary voltage may be set higher or lower than the frequencies of the first voltage V1and the second voltage V2. Moreover, when the frequencies of the first voltage V1and the second voltage V2are different, the frequency of the auxiliary voltage may be set to be between the frequencies of the first voltage V1and the second voltage V2.

In addition, the configuration of the unit-electrodes in the first embodiment and the like is not necessarily limited. Therefore, for example, in the first embodiment and the like, the first electrode E1, the second electrode E2, the auxiliary electrode EC, the first auxiliary electrode EC1, and the second auxiliary electrode EC2are formed on the same level, but they are not limited to such an aspect, and may be formed on different levels. Further, the first electrode E1, the second electrode E2, the auxiliary electrode EC, the first auxiliary electrode EC1, and the second auxiliary electrode EC2may be formed in contact with the resistance layer HR without intervening the insulating layer IS1between them, or may be arranged closer to the liquid crystal layer LC than the resistance layer HR. Further, it is preferable that the distance from the auxiliary electrode EC, the first auxiliary electrode EC1, and the second auxiliary electrode EC2to the liquid crystal layer LC is less than or equal to the distance from at least one of the first electrode E1and the second electrode E2to the liquid crystal layer LC. Further, for example, when the auxiliary electrode EC, the first auxiliary electrode EC1, and the second auxiliary electrode EC2are formed in a linear shape with a narrower line width than the first electrode E1and the second electrode E2, by making sure that the distance to the liquid crystal layer LC is not larger than at least one (or both) of the first electrode E1and the second electrode E2, the voltage applied to the auxiliary electrode EC etc. is less likely to be attenuated, making it easier to control the potential gradient.

In addition, in the liquid crystal element100of the first embodiment etc. that has the unit-electrodes U1and U2concentrically arranged in an arc shape and has a function as a Fresnel lens, on the other hand, by continuously arranging the unit-electrode U1and U2in a rectangular shape, a liquid crystal element having a function as a linear Fresnel lens can be obtained. In this case, for example, the width of the unit-electrode is arranged to become narrower as the curvature of the linear Fresnel lens increases, but this is not necessarily limited. Furthermore, when applying the linear Fresnel lens to eyeglasses, two liquid crystal elements each having continuous rectangular unit-electrodes U1and U2are arranged so that their optical axes are perpendicular to each other, and apply as the lenses for the eyeglasses. In addition, the linear Fresnel lens may have a configuration including a plurality of common input sections as shown inFIG.12A, or may have a configuration with unit-electrode arrangement density as shown inFIG.12B, and the transmitted light restriction section RS may be provided.

In addition, when the wall portion WL is made of an ultraviolet curing resin as in the sixth embodiment, for example, a thin film to limit the incidence of ultraviolet rays may be formed on the liquid crystal element100. By configuring eyeglasses equipped with the liquid crystal element100with a thin film that restricts the incidence light of wavelength at which the photo-curable liquid crystal monomer is cured, it is possible to reduce the deterioration of the optical performance due to the curing of the remaining photo-curable monomer.

Further, the present invention is not limited to the embodiments described above, and various modifications and combinations are possible without departing from the gist thereof. For example, the configurations described in the above embodiments can be replaced with configurations that are substantially the same, have the same effects, or can achieve the same objectives.

REFERENCE SIGNS LIST

100,100A liquid crystal element, B1, B2transparent substrate, LC liquid crystal layer, U1, U2unit-electrode, CT center electrode, CC core electrode, LA optical axis, RF refractive index distribution, E1first electrode, E2second electrode, E3counter electrode,71first lead wire,72second lead wire,73third lead wire,75fourth lead wire,74,76lead wire connection portion, HR resistance layer, AR area, IS1, IS2, IS3, IL insulation layer, EC auxiliary electrode,81,82,83,84,85,86comb structure, P1, P2, P3, P4distance, GA glass substrate, EC1first auxiliary electrode, EC2second auxiliary electrode, CP1, CP2, CP3common input section, BM shielding layer, WL insulating wall, LN liquid crystal unit, RS transmitted light restriction section, D1, D2electrooculography sensor, D3eye detection sensor.