JP5334116B2 - Low voltage liquid crystal lens - Google Patents

Description

The present invention relates to a liquid crystal lens having a simple structure and capable of realizing a large and thin lens capable of changing a focal length by a low voltage.

A liquid crystal called a nematic liquid crystal has fluidity like a liquid, exhibits anisotropy in electro-optical characteristics, and an effective refractive index can be continuously varied from a value for almost extraordinary light to a value for ordinary light by applying a voltage. Various voltage variable optical devices have been proposed by utilizing this feature.

That is, some nematic liquid crystal cells utilize the property that liquid crystal molecules are aligned in the direction of an electric field. This is a spatial parabolic refractive index distribution by using an electrode having a circular hole pattern with a diameter of several hundreds of microns and utilizing the liquid crystal molecule alignment effect due to an axisymmetric non-uniform electric field. Patent Documents 1 and 2 report methods for obtaining liquid crystal lenses having characteristics. Such a small liquid crystal lens having a diameter of millimeter or less is called a liquid crystal microlens.

In the liquid crystal microlens structure proposed in Patent Documents 1 and 2, if a lens with a large aperture diameter is formed by increasing the diameter of the circular hole pattern while keeping the thickness of the liquid crystal layer constant, an axial symmetry generated by the aperture of the electrode This non-uniform electric field does not occur to the vicinity of the center of the opening, so that there is a problem that a spatial alignment distribution of liquid crystal molecules necessary for obtaining lens characteristics cannot be obtained. As a method of increasing the effective opening diameter, a transparent high resistance film is provided so as to be in contact with the liquid crystal layer through an alignment film in a circular opening provided in electrodes on two substrates sandwiching the liquid crystal layer. Thus, there has been proposed a liquid crystal lens having a structure in which an electric field is generated up to the center of the opening using the potential distribution due to the electric resistance of the high resistance film surface (Patent Document 3).

However, with this method, the potential distribution due to the resistive film provided on the substrate surface facing the liquid crystal layer has a predetermined potential distribution shape that provides a parabolic refractive index distribution based on the orientation distribution of the liquid crystal molecules. Therefore, it is very difficult to change the focal length over a wide range while maintaining good lens characteristics.

Further, an electrode having an opening having a structure similar to the liquid crystal microlens proposed in Patent Document 1 is arranged so as to be placed at a certain distance from the liquid crystal layer without contacting the liquid crystal layer. Even if the diameter of the opening is increased, an axially symmetric non-uniform electric field can be generated up to the vicinity of the center of the opening. Based on this principle, a method has been proposed in which an insulating layer is inserted between the liquid crystal layer and the circular hole pattern electrode to maintain the distance from the liquid crystal layer to the circular hole electrode (Patent Document). 4, Non-Patent Documents 1 and 2), there is a condition that the ratio of the diameter of the circular hole pattern and the thickness of the liquid crystal layer that can obtain the best characteristics in the liquid crystal microlens needs to be about 2: 1 to 3: 1 It has been shown that liquid crystal lenses that are relaxed and have a large diameter can be constructed.

Further, in a liquid crystal lens in which an insulating layer is inserted between the liquid crystal layer and the circular hole pattern electrode, a transparent third electrode is arranged outside the circular hole pattern electrode or inside the circular pattern electrode, and the voltage is increased by two voltages. There has been reported a liquid crystal lens in which the focal length can be varied over a wide range from a concave lens characteristic to a convex lens characteristic while maintaining good characteristics by driving (Patent Document 5).

Non-Patent Document 3 and Non-Patent Document 4 disclose that the driving voltage of the liquid crystal lens can be reduced by using a glass material having a high relative dielectric constant as the insulating layer.

However, in the structure in which an insulating layer is provided in order to set the distance between the liquid crystal layer and the circular hole pattern electrode proposed in Patent Documents 4 and 5, the insulating layer disposed between the liquid crystal layer and the electrode For this reason, there is a problem that the driving voltage becomes high, and in particular, in order to obtain a lens having a large aperture, it is difficult to obtain a lens having a large aperture because the thickness of the insulating layer is further increased and a high voltage is required. There is a problem that the thickness of the entire liquid crystal lens cannot be reduced due to the thickness of the insulating layer.

In order to solve this problem, a high-resistance liquid layer or a high-resistance thin film is provided as a transparent high-resistance layer in the transparent insulating layer to relay the potential distribution, that is, the potential of the high-resistance film surface. Patent Document 6 discloses a method for reducing the driving voltage as a result of reducing the effective thickness of the transparent insulating layer by adopting a structure in which an axially symmetric non-uniform electric field is generated up to the center using the distribution. And Non-Patent Documents 4 and 5.

However, when a transparent high resistance layer is inserted in the transparent insulating layer, at least two transparent insulating layer substrates are required, which complicates the manufacturing process and reduces the thickness of the entire lens. There was a problem that there was a limit. Furthermore, since the alignment effect of the liquid crystal molecules due to the non-uniform electric field does not reach the entire area of the liquid crystal layer, there is a problem in that the effective refractive index variable range, that is, the focal range of the liquid crystal layer cannot be widened.

JP-A-11-109303 JP-A-11-109304 Japanese Patent Laid-Open No. 2003-29001 JP 2004-4616 A JP 2006-91826 A JP 2008-203360 A

Proceedings of the 49th Applied Physics-related Joint Lecture Meeting, “M.Ye and S. Sato”, “Optical properties of liquid crystal lens of any size” , March 2002, 28p-X-10, P.M. 1277 M. Ye and S. Sato, “Optical properties of liquid crystal lens of any size”, Japanese Journal of Applied Physics, May 2002, Vol. 41, No.5, P.L571-L573 Hage, Wang, S. Sato, “Effects of Dielectric Constant of Glass Substrates on Properties of Liquid Crystal Lens” , IEEE Photonics Technology Letters, Vol. 19, No. 17, P.1295-1297 (2007) Hage, Wang, Susumu Sato, “Study on Low Voltage Driving Method for Liquid Crystal Lenses”, Proceedings of the 2007 Annual Meeting of Japanese Liquid Crystal Society, September 2007, 2pC01 Hage, Wang, Maki Yamaguchi, Susumu Sato (M. Ye, B. Wang, M. Yamaguchi and S. Sato), “Lowering Driving Voltages for Liquid Crystal Lens Using Weakly Conductive Thin Film) ”, Japanese Journal of Applied Physics, June 2008, Vol. 47, No. 6, pp. 4597-4599

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal lens that solves the above problems, can be stably driven at a low voltage, and has a large aperture while maintaining good optical characteristics. It is another object of the present invention to provide a liquid crystal lens that improves the utilization efficiency of the liquid crystal layer and has a large reproducibility and can greatly change the focal length at a low voltage.

In order to solve the above-described problems, the present invention basically includes a first substrate having a transparent first electrode, a second electrode having a hole, and the first substrate and the second electrode. Between the second electrode and the liquid crystal layer, and a liquid crystal layer that is accommodated so as to face the first electrode and that aligns liquid crystal molecules in one direction. A liquid crystal lens that controls the alignment of liquid crystal molecules by applying a voltage between the first and second electrodes, or a third electrode that is disposed on the second electrode via an insulating layer. In the liquid crystal lens or the liquid crystal lens in which the third electrode is disposed at an interval in the hole of the second electrode, a second voltage independent of the first voltage is applied to the third electrode. And either of the first voltage or the second voltage value The optical characteristic is variably controlled by changing one of the second voltage with respect to the first voltage and the first voltage with respect to the second voltage. In the liquid crystal lens capable of achieving the above, a transparent high resistance layer is disposed on the transparent insulating layer facing the liquid crystal layer.

In addition, the relative dielectric constant of the transparent insulating layer is 8 or more, and the dielectric constant of the transparent insulating layer can be distributed axisymmetrically.

Further, a transparent medium having a specific resistance in the range of 1 Ω · m to 100000000 Ω · m can be used instead of the transparent insulating layer.

The resistance value of the transparent medium is distributed in an axisymmetric manner.

Also further characterized in that the resistance value of the transparent, high-resistance layer is distributed axisymmetrically.

By the above means, a thin lens having a simple structure and capable of being driven by a low voltage can be realized. Moreover, even if the aperture of the lens is increased, the focal length can be changed with a low voltage. Further, the focal length can be varied greatly efficiently by electrical control with a low voltage without the operation of mechanically moving the lens back and forth as in the prior art.

FIG. 1A is a configuration explanatory view showing an embodiment of a liquid crystal optical device according to the present invention, and FIG. 1B is a plan view of an electrode 22 in FIG. FIG. 2 is an explanatory diagram showing the configuration of a specific embodiment of the present invention. The configuration of the liquid crystal lens having two liquid crystal layers and a transparent high resistance layer in order to increase the lens power. FIG. FIG. 3 shows a liquid crystal lens having the configuration shown in FIG. 2, and a convex lens based on an optical phase difference distribution in the liquid crystal layer when a voltage V1 of 40 V (20 kHz) and a voltage V2 of 20 V, 26 V, and 32 V (each 20 kHz) are applied. Concave lens characteristics due to the optical phase difference distribution in the liquid crystal layer when the characteristics (area where the optical phase difference is positive) and the voltages V2 of 40V (20 kHz) and V1 of 20V, 26V and 32V (each 20 kHz) are applied. It is an optical phase distribution diagram showing a region where the optical phase difference is negative. FIG. 4 is a diagram showing a change in lens power depending on an applied voltage (20 kHz), and shows dependency of lens power on applied voltage when a transparent high resistance layer is not provided and when a transparent high resistance layer is provided. FIG. FIG. 5 shows the result of obtaining the optical phase difference distribution by simulation when a transparent substrate having a relative dielectric constant of 50 is used as the transparent insulating layer 12 in FIG. Here, the surface resistance value of the transparent high resistance layer is 100 MΩ, and V1 = 8 Vrms and V2 = 1.5 Vrms are applied as the respective applied voltages (20 kHz sine wave). FIG. 6 is a result of optical phase difference distribution obtained by simulation when a high resistance substrate having a specific resistance value of 1 kΩ · m is used as a transparent medium instead of the transparent insulating layer in FIG. Here, the specific resistance value of the transparent high resistance layer is 1 Ω · m, and V1 = 8 Vrms and V2 = 1.5 Vrms are applied as respective applied voltages (20 kHz sine wave).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, the basic configuration will be described.

FIG. 1A shows a configuration in which a basic configuration of a liquid crystal lens according to an embodiment of the present invention is viewed from a cross section. The transparent first electrode 21 is formed on the first substrate 11, and the liquid crystal cell 1 is configured by overlapping the second substrate 12 via a spacer (not shown) for maintaining a predetermined thickness. . Between the 1st board | substrate 11 and the said 2nd board | substrate 12, the 1st liquid crystal layer 31 which accommodated the liquid crystal molecule in one direction accommodated so that the 1st electrode 21 might be opposed is provided.

An alignment film 51 having an effect of aligning liquid crystal molecules in one direction is disposed on the surface of the first substrate 11 in contact with the liquid crystal layer 31. Further, a high resistance film 41 is disposed as a transparent high resistance layer on the side of the second substrate 12 facing the liquid crystal layer. Note that no voltage is directly applied to the high resistance film 41.

By rubbing the alignment film 51 and the high resistance film 41 in one direction, the director corresponding to the major axis direction of the liquid crystal molecules forms an angle of about 1 to 2 degrees from the substrate surface called a pretilt angle. It is in a state of being oriented.

FIG. 1B is a plan view of the liquid crystal lens of FIG. 1A, and the second substrate 12 has a second electrode 22, and the second electrode 22 has a circular shape. A hole 22-1 is formed. A first voltage V 1 is applied between the first electrode 21 and the second electrode 22. A circular transparent third electrode 23 having the same center electrically insulated by a slit is formed in the circular hole 22-1. The circular transparent third electrode 23 is arranged so that the second voltage V2 can be applied from the outside through a lead portion 23-1 that is similarly insulated from the second electrode by a slit.

Here, a case where the third electrode 23 is removed from the configuration shown in FIG. 1 will be described. When the first voltage V1 higher than the threshold value is applied between the first electrode 21 and the second electrode 22, an axially symmetric non-uniform electric field is applied to the liquid crystal layer 31, and the alignment of the liquid crystal molecules by the alignment film surface is controlled. The alignment effect of the force and the axially symmetric non-uniform electric field is aligned in an elastically balanced state, and the convex lens effect is mainly obtained, thereby forming the liquid crystal lens A. Details of the operation principle of the liquid crystal lens A are disclosed in Patent Document 4.

In the liquid crystal lens having a configuration excluding the third electrode 23 from the configuration shown in FIG. 1, the complex characteristic that the change characteristic of the focal length of the liquid crystal lens with respect to the increase of the externally applied voltage once becomes the shortest and then increases. In addition, since there is a problem that it is difficult to obtain the concave lens characteristic, the third electrode is provided in addition to the second electrode as shown in FIG. In the case where the third electrode shown in FIG. 1 is arranged, the second voltage V2 independent of the first voltage V1 can be applied to the third electrode 23. Then, the liquid crystal lens B is obtained which can obtain the first stage optical characteristics based on the first voltage V1 and the second stage optical characteristics based on the second voltage V2. Details of the operation principle of the liquid crystal lens B are disclosed in Patent Document 5. According to the liquid crystal lens B, functions as a convex lens and a concave lens can be obtained.

Particularly in this liquid crystal lens, since the high resistance film 41 is disposed as a transparent high resistance layer between the transparent insulating layer 12 and the liquid crystal layer 31, the second electrode 22 (circular pattern electrode) having a hole and the liquid crystal layer are disposed. As a result of the relay effect of the potential distribution as a result of the formation of dielectric coupling between the high-resistance film 41 and 31, an axially symmetric non-uniform electric field is generated in the circular holes in the liquid crystal layer even when the thickness of the transparent insulating layer is reduced. As a result, the driving voltage can be lowered. The effect of lowering the drive voltage in a structure in which a high resistance layer is inserted in the transparent insulating layer is disclosed in Patent Document 6, Non-Patent Document 4, and the like.

Next, specific examples will be described. In FIG. 2, the first substrate 11 is a transparent glass plate having a thickness of 300 μm, and a transparent first electrode 21 made of indium tin oxide (ITO) is formed on the inner surface side in contact with the first liquid crystal layer 31. Is formed. This liquid crystal lens is provided with two liquid crystal layers in order to widen the variable range of the lens power corresponding to the reciprocal of the focal length. The first liquid crystal layer 31 and the second liquid crystal layer 32 are separated by a third substrate 13 made of a glass plate having a thickness of 70 μm. The second substrate 12 is a glass plate having a thickness of 300 μm. An ITO electrode 22 serving as a second electrode is formed on the surface of the second substrate opposite to the surface in contact with the second liquid crystal layer 32. A circular hole 22-1 (for example, 2 mm in diameter) is formed in the region that becomes the liquid crystal lens portion of the second electrode 22 as shown in FIG.

Here, a first liquid crystal layer 31 (for example, a thickness of 30 μm) in which liquid crystal molecules are aligned in one direction is sealed between the first electrode 21 and the third substrate 13. A second liquid crystal layer 32 (for example, 30 μm thick) in which liquid crystal molecules are aligned in one direction is also sealed between the transparent insulating layer 12 with the second electrode and the third substrate 13. Here, a polyimide film is applied as an alignment film 51, 52, 53 to a thickness of about 150 nm on the electrodes and the surface of the substrate sandwiching the liquid crystal layer, heat treated and stabilized, and then rubbed in one direction. Yes.

As the liquid crystal material of the first liquid crystal layer 31 and the second liquid crystal layer 32, ZLI6080 (manufactured by Merck) was used. In order to keep the first liquid crystal layer 31 and the second liquid crystal layer 32 at a predetermined thickness, a spherical spacer having a diameter of 30 μm (not shown) dispersed in an adhesive is used. The liquid crystal is sealed around the periphery of the substrate with an adhesive.

When the rubbing treatment is performed, it is generally known that the major axis direction of the liquid crystal molecules is in a state of being inclined at a small angle of about several degrees or less called a pretilt angle with respect to the rubbing direction. Therefore, when the rubbing directions with respect to the alignment film on the opposite substrate are processed in opposite directions (referred to as anti-parallel), the liquid crystal molecules are uniformly aligned with a pretilt angle on the substrate surface. Yes.

In a liquid crystal lens having a circular hole electrode, when the number of liquid crystal layers is one, the direction in which liquid crystal molecules rise from the substrate surface by the effect of an electric field on both sides of the central axis of the circular hole region in the cross section in the rubbing direction of the liquid crystal layer However, due to the effect of the pretilt angle, they are not completely the same, and it is known that aberrations occur in the optical characteristics. As shown in FIG. 2, the liquid crystal layer is made into two layers, and the directions of the liquid crystal molecular alignment are opposite to each other, thereby suppressing the aberration caused by the effect of the pretilt angle based on the molecular alignment processing by rubbing. .

As the transparent high resistance layer 41, a resin conductive film (TWH-1 manufactured by Gemco) in which conductive fine particles having a thickness of about 1 μm were dispersed was used. The resistance of the resin-based conductive film used in this example was about 50 MΩ / m2 to 200 MΩ / m2 in terms of sheet resistance. Other inorganic thin films, for example, transparent thin films such as ITO, zinc oxide, titanium oxide, zinc sulfide, or a mixed system of these materials having a resistance value set to an optimum value can also be used. The use of an inorganic thin film for the high resistance layer 41 is advantageous in that it is stable and has a long life. The resin-based conductive film is also rubbed in the same manner as the polyimide film to provide an alignment effect on the liquid crystal.

The transparent insulating layer 12 is not limited to this name as its name, but is a transparent insulator having a transparent high resistance layer, a transparent insulator having an electric field relay layer, or a transparent having a dielectric coupling function. Names such as an insulator or a transparent medium having a very high resistance value are possible.

In the liquid crystal lens manufactured using ZLI 6080 (manufactured by Merck) as the liquid crystal material, the diameter of the circular hole 22-1 is 2 mm, the thickness of each of the first and second liquid crystal layers 31 and 32 is 30 μm, By applying the voltage and the second voltage respectively, the optical phase difference distribution characteristic corresponding to the convex lens as shown in FIG. 3 (upward convex portion, V1 as 20 kHz 40 Vrms, V2 applies the voltage shown in the figure) ) And a phase difference distribution characteristic corresponding to a concave lens (lower convex portion, V2 is 40 Vrms, and V1 is applied with the voltage shown in the figure). The relationship between the lens power (diopter) corresponding to the reciprocal when the focal length is expressed in meters and each applied voltage is as shown in FIG. 4, and a continuous change in lens power is obtained. A variable effect of lens power of about 0 to 7 diopters (1 / m) was obtained on the convex lens side and the concave lens side. FIG. 4 also shows changes in applied voltage and lens power when the transparent high resistance layer is not used. When the transparent high resistance layer is not used, it can be seen that the applied voltage is about twice as high because a glass substrate having a thickness of 800 μm is used as the transparent insulating layer in order to obtain good lens characteristics.

Next, another embodiment will be specifically described. In the liquid crystal lens having the structure shown in FIG. 1, a transparent substrate having a dielectric constant larger than that of a normal glass substrate (about 7) is used as the second substrate used as the insulating layer. Then, the operating voltage of the liquid crystal lens can be further reduced. Here, the surface resistance value of the transparent high resistance layer is 100 MΩ / m 2, and for example, the result of obtaining the optical phase difference distribution by simulation when the relative dielectric constant is 50 is shown in FIG. The case where a voltage of 8 Vrms as V1 and 1.5 Vrms as V2 is applied is shown. The optical phase difference characteristic in the range corresponding to the lens area near the center is a square characteristic (parabola), and a good lens effect can be obtained. That is, by using a transparent insulating layer having a large relative dielectric constant, the operating voltage can be lowered to 10 Vrms or less. As the transparent substrate having a large relative dielectric constant, glass or ceramics having a high dielectric constant can be used.

Further, the variable range of the lens power of the liquid crystal lens can be expanded by distributing the dielectric constant of the transparent insulating layer in an axially symmetrical manner. For example, when used as a convex lens, by reducing the dielectric constant of the region corresponding to the center of the circular opening and giving it a distribution that increases toward the periphery, the potential distribution characteristics that bring about the convex lens effect are further improved. As a result, the variable range of the lens power in the convex lens region can be expanded. As the substrate having the dielectric constant distributed in an axisymmetric manner, a plastic plate or the like in which the dispersion density of the ferroelectric nanoparticles is controlled can be used.

On the other hand, by setting the distribution characteristics such that the maximum is at the central portion of the circular opening and the relative dielectric constant gradually decreases toward the periphery, the variable range of the lens power as the concave lens characteristics can be expanded.

Furthermore, another embodiment will be described. For example, a first substrate having a transparent first electrode, a second electrode having a hole, and a space between the first substrate and the second electrode so as to face the first electrode A liquid crystal layer that aligns liquid crystal molecules in one direction, a transparent medium is disposed between the second electrode and the liquid crystal layer, and a voltage is applied between the first and second electrodes. In addition, Non-Patent Document 3 discloses a method of reducing the driving voltage of a liquid crystal lens by using a glass substrate having a high relative dielectric constant as a transparent insulating layer in a liquid crystal lens that controls the alignment of liquid crystal molecules. Similarly, as a method of reducing the driving voltage in the liquid crystal lens having the above structure, the operation of the liquid crystal lens is performed by using a transparent medium having a slight conductivity (that is, a very high resistance value) instead of the insulating layer. The voltage can be greatly reduced.

Further, a third electrode is disposed with respect to the second electrode via an insulating layer or in the hole of the second electrode, and the third voltage is applied to the third electrode. Is configured to be able to apply an independent second voltage, and either the first voltage or the second voltage value is fixed, and the second voltage with respect to the first voltage. In the liquid crystal lens, the optical characteristic can be variably controlled by changing either one of the first voltage with respect to the second voltage. In addition, by using a transparent medium having a slight conductivity (that is, having a very high resistance value), the operating voltage of the liquid crystal lens can be greatly reduced.

The value of the specific resistance of the transparent medium used in place of these transparent insulating layers depends on the thickness of the transparent medium, but good characteristics can be obtained, for example, when the specific resistance ranges from 1 Ω · m to 100000000 Ω · m. ing.

Furthermore, when a transparent high resistance layer having a surface resistance value of 100 MΩ is used in the configuration shown in FIG. 1 and a transparent medium having a specific resistance of 1 kΩ · m is used instead of the transparent insulating layer 41, V1 is 8 Vrms, FIG. 6 shows optical phase difference distribution characteristics induced in the liquid crystal layer when a voltage of 1.5 Vrms (both 20 kHz sine wave) is applied as V2. The distribution characteristic is almost a square characteristic (parabola), and good lens characteristics can be obtained.

Further, by distributing the resistivity of the transparent medium in an axisymmetric manner, the variable range of the lens power can be expanded as in the case where the dielectric constant is axisymmetrically distributed. As the substrate in which the specific resistance of the transparent medium is axisymmetric, a plastic plate or the like in which the density of nanoparticles of indium oxide added with impurities is controlled and dispersed can be used.

In the structure shown in FIG. 1, by using a substrate having a lens effect as the first substrate and either or both of the transparent insulating layer and the transparent medium, the focal point can be changed from a certain fixed focal point. It is possible to form a compact lens system that is integrated as a whole. Here, in order to give the substrate a lens effect, the shape of the substrate may be a curved surface shape, but it is more convenient when the refractive index is distributed symmetrically in a parallel plate type. is there.

As described in the embodiment of the present invention, the alignment effect can be given to the liquid crystal molecules by rubbing the resin film (TWH-1 manufactured by Gemco) used as the transparent high resistance layer. Therefore, a more stable liquid crystal lens can be constructed by using a resin film having a higher orientation effect, such as a polyimide film, and having a high resistance characteristic.

When the resistance value of the transparent high resistance layer 41 gradually changes from the position corresponding to the center of the circular hole pattern to the peripheral portion, the distribution shape of the voltage effectively applied to the liquid crystal layer can be changed. . At present, only about 40% of the thickness of the liquid crystal layer is used, but the liquid crystal layer can be used more effectively, and as a result, the variable range of the lens power in the liquid crystal lens can be expanded.

Furthermore, by continuously changing the alignment effect of the liquid crystal molecules accompanying the electric field distribution in the liquid crystal layer around the circular opening, the lens effect is continuously weakened from the region having the lens effect to the region having no lens effect. Thus, a low-voltage driving liquid crystal lens characterized by having excellent characteristics can be formed.

When the liquid crystal lens according to the present invention is used as a spectacle lens, the center of the region showing the lens effect, that is, the center of the circular hole pattern is shifted from the center of the transparent first substrate to the peripheral portion, particularly the obliquely lower portion. By disposing at a certain position, it is possible to configure a pair of spectacles that can be switched to a convex lens state for reading or the like, and to switch to a through state by voltage removal or a slightly concave lens state in other cases. . According to the present invention, by using the transparent high resistance layer, a large-diameter liquid crystal lens that operates at a low voltage can be configured, and thus it is useful as a spectacle lens for such a perspective.

In this embodiment, the transparent high resistance layer 41 is disposed between the transparent insulating layer 12 and the liquid crystal layer. However, the circular pattern electrode 22 and the transparent insulating layer 12 are opposite to the liquid crystal layer of the transparent insulating layer 12. An insulating layer may be interposed between the two.

In this embodiment, the case where the circular pattern electrode is only one layer has been described. However, the circular pattern electrode may be provided on both sides of the liquid crystal layer. In any case, a liquid crystal lens having excellent symmetry in the spatial distribution characteristics and optical characteristics of the refractive index can be configured by using such a symmetric structure.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment. Further, although one liquid crystal lens is shown, a configuration in which a plurality of liquid crystal lenses are arranged may be used. Further, it may be a two-dimensional array such as a compound eye.

The low-voltage drive liquid crystal lens of the present invention is different from ordinary passive optical devices in that the voltage and the effective refractive index of the liquid crystal as a medium are variably controlled by applying a voltage between the electrodes. A lens capable of adjusting the aberration is realized. Therefore, various applications such as an autofocus lens, a magnifying lens, a zoom lens, a lens of an image pickup unit used as a visual function in a robot, and a spectacle lens for both perspective by increasing the aperture are possible. .

DESCRIPTION OF SYMBOLS 11 ... 1st board | substrate, 12 ... Transparent insulating layer, 13 ... Glass plate, 41 ... Transparent high resistance layer, 21 ... 1st electrode, 22 ... 2nd Electrode, 22-1 ... Opening, 23 ... Third electrode, 23-1 ... Electrode take-out part, 31 ... Liquid crystal layer, 32 ... Liquid crystal layer, 51, 52, 53 ..Alignment films

Claims (8)

A first substrate having a transparent first electrode, a second electrode having a hole, and a space between the first substrate and the second electrode so as to face the first substrate. A liquid crystal layer for aligning liquid crystal molecules in one direction; a transparent insulating layer is disposed between the second electrode and the liquid crystal layer; and a voltage is applied between the first and second electrodes. A liquid crystal lens for controlling the orientation of liquid crystal molecules, wherein a transparent high resistance layer is disposed on the transparent insulating layer facing the liquid crystal layer. 2. The low-voltage driving liquid crystal lens according to claim 1, further comprising a third electrode disposed with an interval from the second electrode through an insulating layer or in the hole of the second electrode. 3 is configured to be able to apply a second voltage independent of the first voltage, and either the first voltage or the second voltage is fixed, and the first voltage Low voltage driving characterized in that the optical characteristic can be variably controlled by changing either the second voltage with respect to the voltage or the first voltage with respect to the second voltage. Liquid crystal lens. 3. The low voltage drive liquid crystal lens according to claim 1, wherein the transparent insulating layer has a relative dielectric constant of 8 or more. 4. The low voltage drive liquid crystal lens according to claim 1, wherein the dielectric constant of the transparent insulating layer in the low voltage drive liquid crystal lens is axisymmetrically distributed. A first substrate having a transparent first electrode, a second electrode having a hole, and a space between the first substrate and the second electrode so as to face the first electrode. And a liquid crystal layer for aligning liquid crystal molecules in one direction, a transparent medium is disposed between the second electrode and the liquid crystal layer, and a voltage is applied between the first and second electrodes. In the liquid crystal lens for controlling the alignment of liquid crystal molecules, the transparent medium has a specific resistance in the range of 1 Ω · m to 100000000000000 Ω · m, and is transparent on the side of the transparent medium facing the liquid crystal layer. A low voltage driving liquid crystal lens characterized by disposing a high resistance layer . The low-voltage driving liquid crystal lens according to claim 5, further comprising a third electrode disposed with an interval between the second electrode via an insulating layer or in the hole of the second electrode, A second voltage independent of the first voltage can be applied to the third electrode, and either the first voltage or the second voltage is fixed, and the first voltage is fixed. The optical characteristic can be variably controlled by changing either the second voltage with respect to one voltage or the first voltage with respect to the second voltage. In the voltage driven liquid crystal lens , a transparent high resistance layer is disposed on a side of the transparent medium facing the liquid crystal layer. Low-voltage drive liquid crystal lens resistivity of your Keru the transparent medium to low voltage driving the liquid crystal lens according to claim 5 or 6, characterized in that distributed axisymmetrically. 8. The low voltage driving liquid crystal lens according to claim 1 , wherein the resistance value of the transparent high resistance layer is distributed in an axisymmetric manner.