JP2011150076A - Liquid crystal optical element and method for manufacturing liquid crystal optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal optical element that ensures an amount of liquid crystal to be filled, is capable of stable orientation, obtains a sufficient optical distance L, and improves a response speed, and to provide a manufacturing method therefor. <P>SOLUTION: A liquid crystal optical element 100 includes: a substrate 10 on which a common electrode 20 is formed; a substrate 11 on which a first driving electrode 21 and a second driving electrode 22 are formed; a porous structure 12; and liquid crystal 40. The porous structure 12 is formed by subjecting a high purity aluminum material to anodic oxidation. A large number of through-holes 13 of the porous structure 12 are formed in a circular shape. Without forming an alignment layer on the internal wall 12a of the porous structure 12, liquid crystal in the holes is horizontally oriented by applying a magnetic field thereto. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal optical element such as a liquid crystal lens and a liquid crystal aberration correction element, and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, various liquid crystal optical elements configured by sandwiching liquid crystal between substrates on which electrodes are formed are known. For example, there are various optical disk devices such as CDs and DVDs as information recording media, and these optical disk devices cause aberrations (distortion of condensing spots) due to thickness deviation or warping caused by rotation. Must be corrected to ensure recording / reproduction accuracy. For this reason, a liquid crystal aberration correction element in which liquid crystal is sandwiched between substrates on which electrodes are formed in concentric rings is used, whereby different phase control is performed at the center and outer edge of the light beam (for example, patents) Reference 1).

  In a conventional liquid crystal optical element, the molecular alignment state of the liquid crystal is electrically controlled, thereby changing properties such as the refractive index with respect to light. By controlling the refractive index distribution in two or three dimensions, the amount of phase lag in each optical path and the refractive state of the optical path can be controlled, so liquid crystal lenses and liquid crystal aberration correction elements that can electronically change the focus It is a functional element useful as an optical element. However, in order to maximize the light refraction effect useful for practical applications, it is necessary to hold a sufficient amount of liquid crystal along the optical path between the corresponding alignment films of the liquid crystal optical cell. Therefore, the thickness d of the liquid crystal layer (between the two alignment films) d needs to be extremely thick, such as about 30 to 100 μm, compared to about several μm for a normal liquid crystal display cell.

  The response speed of the liquid crystal is known to be inversely proportional to the square of the thickness d of the liquid crystal layer (between both alignment films) d. In the case of such a thick liquid crystal optical cell, the response time is It will be several hundred ms to several minutes. That is, many conventional liquid crystal optical elements have a problem that the response speed is slow.

  The slow response speed when controlling the equipment is a major limitation for the variable focus lens function and aberration correction function using the liquid crystal optical element, and has been a problem for practical application.

  In order to solve the above drawbacks, the present applicant has proposed a liquid crystal optical element having a plurality of substrates on which electrodes are formed and a porous structure sandwiched between the plurality of substrates and into which liquid crystal is injected. (For example, refer to Patent Document 2).

  In addition, as a conventional alignment process for a liquid crystal cell substrate, an alignment process method using a magnetic field has been proposed (see, for example, Patent Document 3).

  In this alignment processing method, a magnetic field is applied after an organic film as an alignment film is applied to a substrate. Thereby, the initial alignment of the liquid crystal by the alignment film induces the liquid crystal alignment without going through the rubbing process.

JP 2002-237077 A JP 2008-203574 A JP-A-3-279922

  However, as described above, the liquid crystal optical element described in Patent Document 1 needs to transmit a thick liquid crystal layer and ensure a sufficient optical distance L in order to obtain a refractive index change necessary for application. .

However, it is known that as the liquid crystal layer becomes thicker, the response times τ _r and τ _d become slower in proportion to the square of the thickness of the liquid crystal layer (between both alignment films) d. Therefore, when the thickness of the liquid crystal layer is increased, there is a problem that the response speed is lowered, and there is a problem in practical use.

  Therefore, the liquid crystal element described in Patent Document 2 proposed by using a porous structure having a through-hole or a non-through-hole can ensure a sufficient optical distance L and greatly increase the response speed. It became possible to improve. In the case of this liquid crystal element, it is necessary to apply an alignment film to the inner surface of the through-hole or non-through-hole of the porous structure during the manufacturing process. When the diameter of the through-hole or non-through-hole is relatively large, there is no particular problem in the manufacturing process. When the pitch of the through holes is 100 to 1000 nm, the hole opening ratio s is 50 to 80%, and the thickness is 50 to 100 μm, when the alignment film is applied to the inner surface of the hole and the alignment treatment is performed, the hole diameter is small, In addition, because of the thickness, the yield is reduced due to uneven processing. In addition, it is very difficult to form an alignment film, and even when the alignment film is formed, there is a defect that the uniformity is insufficient and the filling amount of liquid crystal is reduced.

  In addition, the alignment treatment method described in Patent Document 3 is for the purpose of eliminating the need for surface alignment treatment such as rubbing on the alignment film formed on the liquid crystal cell substrate. In the case of the alignment treatment, there are still problems that the formation of the alignment film itself is difficult and the filling amount of the liquid crystal is reduced.

  Therefore, the present invention ensures the filling amount of the liquid crystal and ensures stable alignment by aligning the liquid crystal in the hole without forming an alignment film on the wall of the through hole or non-through hole of the porous structure. An object of the present invention is to provide a liquid crystal optical element capable of securing a sufficient optical distance L and greatly improving the response speed and a method for manufacturing the same.

  In order to solve the above problems, a method of manufacturing a liquid crystal optical element according to the present invention includes a plurality of substrates on which electrodes are formed, and a porous structure sandwiched between the plurality of substrates and into which liquid crystals are injected. In the method of manufacturing an optical element, an electrode forming step of forming electrodes on a base substrate, a hole pitch of 100 to 1000 nm, a hole opening ratio s of 50 to 80%, and a thickness of 50 to 100 μm A porous structure forming step of forming a porous structure having a large number of through-holes or non-through-holes, an assembly step of disposing the porous structure between the substrates to form cells, and the porous The cell is heated to a predetermined temperature without forming an alignment film on the wall of the through-hole or non-through-hole of the structure, and isotropic phase liquid crystal is injected into the cell. While applying Characterized in that it comprises an alignment step for.

  For example, in the orientation step, the direction of the magnetic field is set to a direction perpendicular to the thickness direction of the porous structure, and the cell is rotated at a predetermined speed around the center of the cell in the magnetic field. Alternatively, in the orientation step, the direction of the magnetic field coincides with the thickness direction of the porous structure.

  For example, in the porous structure forming step, an aluminum material is anodized to form an alumina porous structure.

  In order to solve the above problems, a liquid crystal optical element according to the present invention is a liquid crystal optical element manufactured by the above-described method for manufacturing a liquid crystal optical element, and includes a plurality of substrates on which electrodes are formed, and the plurality of substrates. And a porous structure having a large number of through-holes or non-through-holes in which liquid crystal is injected. The porous structure has a hole pitch of 100 to 1000 nm and a hole opening ratio s of 50 to 80. %, A thickness of 50 to 100 μm, and without forming an alignment film for orienting liquid crystal on the wall surface of the through-hole or non-through-hole of the porous structure, a magnetic field of a certain strength is applied to the through-hole or The liquid crystal injected into the non-through hole is oriented horizontally or vertically with respect to the wall surface.

  According to the method for manufacturing a liquid crystal optical element according to the present invention, a through-hole of a porous structure having a hole pitch of 100 to 1000 nm, a hole opening ratio s of 50 to 80%, and a thickness of 50 to 100 μm or By applying a magnetic field with a certain strength without forming an alignment film on the wall surface of the non-through hole and aligning the liquid crystal in the hole, the filling amount of the liquid crystal can be secured and stable alignment can be achieved.

  According to the liquid crystal optical element of the present invention, a porous structure having a large number of through holes or non-through holes is disposed between substrates constituting the liquid crystal optical cell, and the through holes or non-through holes of the porous structure are provided. By aligning the liquid crystal in the hole by applying a constant magnetic field without forming an alignment film on the wall of the hole, a sufficient optical distance L can be secured and the response speed is greatly improved. And the filling amount of the liquid crystal can be secured.

  Therefore, the response speed as a liquid crystal optical element can be improved, the uniformity of the structure disposed between the electrodes, and the reproducibility of the structure formation can be improved, and optical characteristics such as photorefractiveness. Can be put to practical use as a variable-focus lens that can be electrically controlled, or a liquid crystal aberration correction element that is used to correct aberrations that occur during recording and reproduction with an optical pickup.

  In the alignment step, the direction of the magnetic field matches the thickness direction of the porous structure, whereby the liquid crystal in the holes can be aligned horizontally with respect to the wall surface, and more stable alignment can be achieved.

  In the porous structure forming step, an alumina porous structure having a certain thickness and a large number of circular through holes or non-through holes is obtained by anodizing the aluminum material. Can be formed.

It is a figure which shows the structure (example of through-hole) of the liquid crystal optical element 100 of 1st Embodiment. 2 is a cross-sectional view taken along the line AA showing the configuration of the liquid crystal optical element 100. FIG. 2 is a cross-sectional view taken along the lines BB and CC showing the configuration of the liquid crystal optical element 100. FIG. It is a figure which shows the arrangement | positioning state of the electrode of a board | substrate, and a connection terminal. 3 is a conceptual diagram showing an electric circuit system of the liquid crystal optical element 100. FIG. 2 is a partially enlarged conceptual view showing a configuration of a liquid crystal optical element 100. FIG. 3 is an image diagram showing a configuration of a porous structure 12. FIG. It is the orientation model at the time of the voltage application in the porous structure 12 which has a circular-shaped hole. It is a photograph of the porous structure 12 formed by the anodic oxidation method. FIG. 3 is a process diagram showing a method for manufacturing a porous structure 12. FIG. 6 is a process diagram (part 1) illustrating a method for producing the liquid crystal optical element 100. FIG. 6 is a process diagram (part 2) illustrating the method for producing the liquid crystal optical element 100. It is a flowchart of a liquid-crystal injection | pouring and orientation processing process. It is explanatory drawing of a liquid-crystal injection | pouring and alignment process. It is a partial expansion conceptual diagram which shows the structure (example of a non-through-hole) of the liquid crystal optical element 200 of 2nd Embodiment.

  The best mode for carrying out the liquid crystal optical element and the manufacturing method thereof according to the present invention will be described with reference to the drawings. Here, the lens effect is obtained by applying a partial electric field to liquid crystal molecules arranged in a specific direction in advance, changing the arrangement of the molecules, and utilizing the change in the refractive index distribution generated in the liquid crystal optical cell. An example of the obtained liquid crystal optical element will be described.

  FIG. 1 is a diagram illustrating a configuration of a liquid crystal optical element 100 according to the first embodiment. FIG. 2 is a cross-sectional view taken along line AA showing the configuration of the liquid crystal optical element 100. FIG. 3 is a cross-sectional view showing the configuration of the liquid crystal optical element 100. In FIG. 3, FIG. 3 (a) is a BB cross-sectional view, and FIG. 3 (b) is a CC cross-sectional view. FIG. 4 is a diagram illustrating an arrangement state of electrodes and connection terminals of the substrate. 4, FIG. 4A shows the arrangement state of the electrodes and connection terminals of the substrate 11, and FIG. 4B shows the arrangement state of the electrodes and connection terminals of the substrate 10.

  As shown in FIGS. 1 to 4, the liquid crystal optical element 100 includes a substrate 10 on which a common electrode 20 is formed, a substrate 11 on which a first drive electrode 21 and a second drive electrode 22 are formed, A porous structure 12 having a through-hole 13 and a liquid crystal 40 are included. Without forming an alignment film on the wall surface of the through hole 13 of the porous structure 12, a magnetic field with a certain strength is applied to align the liquid crystal in the hole.

  In this example, the substrates 10 and 11 are glass substrates. The liquid crystal 40 is a nematic liquid crystal (Np liquid crystal) having a positive dielectric anisotropy in which a major axis of a molecule is directed in an electric field direction when a voltage is applied.

  Here, between the common electrode 20, the first drive electrode 21, the second drive electrode 22, and the liquid crystal 40, a generally provided alignment film, a transparent insulating layer, or a reflection provided on the substrates 10 and 11. The prevention film and the like are not shown. Further, the liquid crystal 40 is sealed inside by a sealing material 50. Each terminal is connected to a lead wire or the like for applying a voltage.

Holes are drilled in the thickness direction of the lower substrate 10, and ground terminals V ₀ and heater terminals V _H for connection to the common electrode 20 and the heater electrode 20 h are provided in these holes, respectively. Further, a first drive terminal V ₁ and a second drive terminal V ₂ are provided on the upper substrate 11. Each terminal is formed through hole processing along the inner peripheral surface of the hole and filled with a metal plating / conducting material such as Cr—Au.

  An injection port 32 for injecting the liquid crystal 40 between the substrates 10 and 11 is formed in the upper substrate 11. The shape of the inlet 32 is circular or elliptical, and is appropriately sealed with a sealing material after the liquid crystal 40 is injected.

Further, as shown in FIG. 4A, a circular second drive electrode 22 is disposed at the center of the upper substrate 11, and a first drive electrode 21 is disposed in the vicinity thereof. Second drive electrode 22 is connected to a second driving terminal V _2. Further, the first driving electrode 21 is connected to a first driving terminal V _1. Further, as shown in FIG. 4B, a circular common electrode 20 is disposed at the center of the substrate 10, and a heater electrode 20h is disposed in the vicinity thereof. The common electrode 20 is connected to the ground terminal V _0. Also, the heater electrode 20h is connected to the heater terminal _{V H.}

FIG. 5 is a conceptual diagram showing an electric circuit system of the liquid crystal optical element 100. As shown in FIG. 5, through the power supply V variable resistor R _1, between the first driving terminal V ₁ and the ground terminal V _0, and applies a predetermined voltage V1, through the variable resistor R ₂ Te, applies a predetermined voltage V2 between the second driving terminal V ₂ and the ground terminal V _0. Further, the power supply VH is, a predetermined voltage is applied through a resistor R _H between the ground terminal V ₀ and the heater terminal V _H. This part functions as a heater part of the liquid crystal optical element 100.

  FIG. 6 is a partially enlarged conceptual view showing the configuration of the liquid crystal optical element 100. In FIG. 6, for easy understanding, the configuration of the liquid crystal optical element 100 and the alignment of the liquid crystal are schematically illustrated. FIG. 6A is a diagram illustrating a liquid crystal alignment state when no voltage is applied, and FIG. 6B is a diagram illustrating a liquid crystal alignment state when a voltage is applied. The portion shown in FIG. 6 is the basic structure of the liquid crystal optical element 100. The porous structure 12 is disposed on the lower substrate 10. Further, the upper substrate 11 is disposed above the porous structure 12. A predetermined space is provided between the upper substrate 11 and the porous structure 12. A liquid crystal 40 is filled and held between the lower substrate 10 and the upper substrate 11.

  An alignment film is formed on the inner surface of the substrate 11. Therefore, as shown in FIG. 6, the liquid crystal inside the substrate 11 is aligned in a certain direction (a direction perpendicular to the substrate 11). In addition, without forming an alignment film on the inner wall surface 12a of the porous structure 12, the liquid crystal inside the holes is aligned by applying a magnetic field (see FIGS. 10 to 14 described later). In this case, the liquid crystal is aligned in the horizontal direction with respect to the inner wall surface 12a. At this time, for example, nematic liquid crystal (Np type liquid crystal) having positive dielectric anisotropy is used as the liquid crystal.

  The space between the inner surface of the substrate 11 and the porous structure 12 is several μm due to the manufacturing variation of the porous structure 12, the manufacturing variation of the gap between the upper and lower glass substrates, and the role of the liquid crystal injection path. Liquid crystal is also present in this part. This liquid crystal is a liquid crystal molecule parallel to the light traveling direction, and does not respond to an electric field change acting in the vertical direction on the upper and lower glass substrates.

  As shown in FIG. 6B, when a predetermined voltage is applied to the liquid crystal optical element 100, the liquid crystal aligned in the horizontal direction with respect to the inner wall surface 12a is tilted by receiving a force in the electric field direction, When the electric field becomes strong, it becomes horizontal with respect to the electrode surface. Thereby, the refractive index with respect to light can be electrically controlled, and it becomes a functional element useful as a variable focus lens or an aberration correction element.

  FIG. 7 is an image diagram showing the configuration of the porous structure 12. The through holes of the porous structure 12 shown in FIG. 7 have a circular shape. FIG. 8 shows a liquid crystal alignment model in the porous structure 12 having circular holes (liquid crystal alignment state when a voltage is applied). As shown in FIG. 8, when a voltage is applied, the liquid crystal is aligned radially in a direction perpendicular to the inner wall surface 12a.

  The liquid crystal filled in the porous structure 12 has a pattern arrangement as shown in FIG. 8 when a voltage is applied, macroscopically there is no anisotropy in the in-plane orientation, and it does not depend on the polarization direction. Further, the through-hole 13 of the porous structure 12 is formed in a circular shape, so that it is structurally strong and can increase the hole opening ratio s, and can fill and hold a large amount of liquid crystal.

  The porous structure 12 is formed by, for example, anodizing a high purity aluminum material. FIG. 9 is a photograph of the alumina porous structure 12 formed by an anodic oxidation method. FIG. 9A is a plan photograph of the alumina porous structure 12. FIG. 9B is a cross-sectional photograph of the alumina porous structure 12. The pitch of the through holes of the porous structure is about 500 nm, the diameter of the holes is about 400 nm, and the thickness is about 50 to 100 μm.

  Further, it is desirable that the area of the porous structure 12 (the area seen from the direction of the substrate normal optical path) is smaller, because it contributes to the control of the optical characteristics and the area of the liquid crystal material can be increased. That is, a larger area is expected for the through-hole or non-through-hole portion in which the liquid crystal is filled and held.

  Furthermore, it is desirable that the porous structure 12 has high reliability and stability with respect to the light wavelength.

  As shown in the partial enlarged conceptual diagram of the liquid crystal optical element 100 shown in FIG. 6, the through holes 13 of the porous structure 12 are arranged in a state parallel to the normal direction of the substrate, that is, the light traveling direction, and the liquid crystal molecules 12a are aligned horizontally with respect to 12a.

Further, the narrower the partition wall of the porous structure 12, that is, the larger the pore opening ratio s, the larger the liquid crystal filling / holding ratio, which favors light control. Is defined as
Hole opening ratio s = (Area of hole part) / {(Area of hole part) + (Area of partition wall part)}
In consideration of manufacturing variations and manufacturability of the porous structure 12, the hole opening ratio s is preferably about 50 to 80%.

  The material selection is also an important issue from the viewpoint of the light transmission efficiency of the partition wall, and particularly the weather resistance and temperature dependency with respect to ultraviolet rays. Examples of the electrical insulating material include glass, resin, silicon, carbon, and ceramic materials, and selection according to each application is necessary.

The liquid crystal material exhibits birefringence, degree of magnitude, (referred to as extraordinary light refractive index) refractive index of the liquid crystal molecular long axis direction ne and minor axis of the refractive index n _{o (called} ordinary refractive index) defined by the difference Δn ₍₌ n e -no). In the case of nematic liquid crystals used in many liquid crystal display cells, the sign of Δn (= ne−no) is positive and is classified as a positive crystal.

The following is an example of nematic liquid crystal ZLI-1132 (manufactured by Merck) in order to know the optical function when light is vertically incident on the liquid crystal optical element sandwiching the porous structure 12. Let's make a numerical estimate. The extraordinary light refractive index ne of the ZLI-1132 liquid crystal material is about 1.632, and the normal light refractive index no is about 1.493. When the orientation of the liquid crystal molecules in the through-hole of the porous structure 12 when no voltage is applied is a radial orientation as shown in FIG. 6, the maximum refractive index n _MAX that can be expected is from ne. Slightly smaller, n _MAX = about 1.561. Further, the minimum value n _MIN of the refractive index obtained by applying a voltage in this state is equal to no and n _MIN = 1.493. Therefore, the controllable range δn of the refractive index that can be changed by the voltage is estimated to be about _δn = n _MAX− n _MIN = 0.068. The product of the refractive index value and the geometric distance is called the optical distance. In this case, assuming that the thickness of the liquid crystal layer (the thickness of the porous structure) is d, the maximum and minimum optical distances L are L _MAX = d × n _MAX and L _MIN = d × n _MIN , respectively. Therefore, the optical distance δL = d × δn that can be controlled by voltage is obtained.

The above estimation is for the case where the pore opening ratio s of the porous structure 12 is 100%. However, when the hole opening ratio s decreases, the controllable range δn of the refractive index that can be effectively changed by the voltage also decreases. become. As an example, it is assumed that a portion of the porous structure 12 is an alumina material formed by anodizing a high-purity aluminum material, the average refractive index is about 1.864, and the pore opening ratio s is 50%. In this case, the effective refractive index when the voltage is off is n _MAX = (1.561 + 1.664) × 0.5 = 1.6625, and the effective refractive index when the voltage is on is n _MIN = (1.493 + 1.664) × 0.5 = 1.6285. Become. By applying the voltage, the controllable refractive index range δn is halved when s = 100%, so the optical distance range δL is also halved when s = 100%.

The magnitude (delay amount) Φ of the phase delay of the light when passing through the optical path of the optical distance L can be calculated by the following equation, where λ is the wavelength of the light.
Slow phase amount Φ = L × 2π / λ
Where L: optical distance, λ: light wavelength
Therefore, when the porous structure 12 is alumina and the pore opening ratio s is 50%, the thickness of the liquid crystal layer (the thickness of the porous structure) is d, and the phase delay (slow phase) that can be controlled by voltage If the range of (quantity) is δΦ,
δΦ = (n _MAX −n _MIN ) × d × 2π / λ = 0.035 × d × 2π / λ.

  Hereinafter, the manufacturing method of the liquid crystal optical element 100 of the present invention will be described with reference to FIGS. FIG. 10 is a process diagram showing a method for manufacturing the porous structure 12. FIG. 11 is a process diagram (part 1) illustrating the method for manufacturing the liquid crystal optical element. FIG. 12 is a process diagram (part 2) illustrating the method for manufacturing the liquid crystal optical element. FIG. 13 is a flowchart of the liquid crystal injection / alignment process. FIG. 14 is an explanatory diagram of liquid crystal injection / alignment processing. In FIG. 14, only one liquid crystal cell is shown for easy understanding.

  The manufacturing method of the porous structure 12 shown in FIG. 10 is a method of forming the porous structure 12 by anodizing an aluminum material.

  In this method, as shown in FIG. 10, first, a high-purity aluminum material is used as an aluminum material, and this high-purity aluminum material is formed into a plate having a predetermined thickness (S11). Next, anodizing is performed on the high purity aluminum material (S12). Here, a high-purity aluminum material is connected to one of the anodizing electrodes in an acidic electrolyte such as nitric acid and phosphoric acid, and the other anodizing electrode is placed in the electrolytic solution, and anodized. Anodization is performed by applying a voltage between the electrodes. Thereby, the porous structure 12 which has many through-holes or non-through-holes is obtained.

  Next, the obtained porous structure 12 is subjected to an etching process for expanding the pore diameter (S13), and the pore diameter of the porous structure 12 is set to a predetermined dimension.

  Next, a back etching process is performed on the porous structure 12 that has been subjected to the pore diameter enlargement etching process (S14), and the aluminum material part left by the anodizing process or the part of the hole that is not penetrating is removed. Remove. Thus, a porous structure 12 having circular holes as shown in FIG. 8 is obtained. Then, it is processed into a predetermined shape. For example, it is processed into a circle as shown in FIG.

  As a method for manufacturing the liquid crystal optical element 100, first, as shown in FIG. 11, an electrode material is formed at a predetermined position on the lower substrate 10 by vapor deposition or the like (S101). Here, although the case where the several liquid crystal optical element 100 is formed in the board | substrate which has a fixed magnitude | size is demonstrated, this invention is not limited to this.

Next, a patterning process such as etching is performed to manufacture the electrodes 20 and 20h (S102). In the step of forming the electrodes 20 and 20h, the substrate 10 is provided with a ground terminal V ₀ and a heater terminal V _H.

  Next, after laminating a transparent insulating layer as necessary, a liquid crystal alignment film such as polyimide (PI) is formed (S103). Further, a sealing material 50 for enclosing the liquid crystal is provided around the electrode 20 by printing or the like (S104).

  On the other hand, for the upper substrate 11 to be opposed, an electrode is formed on the base material substrate in the same manner as described above (S201), patterning is performed, and the first drive electrode 21 and the second drive electrode 22 are formed. (S202). Further, a liquid crystal alignment film is formed (S203).

  And as shown in FIG. 12, the porous structure 12 is arrange | positioned (S300). Here, the porous structure 12 formed by the method shown in FIG. 10 is disposed on the lower substrate 10. Next, a liquid crystal cell is formed by combining the lower substrate 10 and the upper substrate 11 so as to face each other (S301).

Subsequently, an isotropic liquid crystal is injected into the liquid crystal cell (inside the sealing material 50) from the injection port 32, sealed, and subjected to an alignment process (S302). Here, as shown in FIGS. 13 and 14, when performing liquid crystal injection and alignment treatment, first, the formed liquid crystal cell is placed on a cell heating heater, and the liquid crystal cell is heated by the cell heating heater. (S311). At this time, the heating temperature is set to the isotropic phase temperature T _N1 + 5 ° C. of the liquid crystal material. Next, a liquid crystal material in an isotropic phase state is injected into the liquid crystal cell (S312). Next, it installs in the magnetic field which consists of N magnetic pole and S magnetic pole, and applies a magnetic field (S313). At this time, the magnetic field strength is 20 kG, and the magnetic field direction is the same as the opening direction of the porous structure 12. That is, the direction of the magnetic field coincides with the thickness direction of the porous structure 12. Then, the liquid crystal cell is gradually cooled while being held in the magnetic field (S314). In this case, the temperature of the liquid crystal cell is gradually cooled to room temperature via the isotropic phase temperature T _N1 . The cooling time is 5 to 15 minutes. Preferably it is about 10 min. Thereby, the liquid crystal inside the through hole or the non-through hole of the porous structure 12 is aligned in the magnetic field direction. That is, the liquid crystal is aligned in the horizontal direction with respect to the inner wall surface 12a and can be stably aligned.

  Then, using the terminals arranged on the substrates 10 and 11 as the base material, the operation of the element is inspected (S303). NG marking is performed about the location where the inspection failed (S304). Thereafter, an antireflection film (AR film) is formed on the entire surface of the base substrate (S305). The AR film may be formed on either the glass substrate 10 side or the substrate 11 side, or may be formed on both.

  Finally, the substrate serving as a base material is cut into individual liquid crystal optical elements 100 using a slicer or the like (S306), and is completed through a single inspection step (S307). In addition, the element which failed in the inspection of a single item is discarded or repaired, or moved to a regeneration process (S308).

  According to the manufacturing method as described above, the porous structure 12 is formed in advance and disposed between the substrates 10 and 11 when the liquid crystal optical element 100 is assembled. Then, the alignment treatment is performed on the liquid crystal inside the porous structure 12 by a magnetic field.

  As described above, in the present embodiment, the liquid crystal optical element 100 includes the substrate 10 on which the common electrode 20 is formed, the substrate 11 on which the first drive electrode 21 and the second drive electrode 22 are formed, and a porous material. The structure 12 and the liquid crystal 40 are included. As a method for forming the porous structure 12, an alumina porous structure is formed by anodizing a high-purity aluminum material. In addition, a large number of through-holes 13 in the porous structure 12 are formed in a circular shape, and an alignment film is not formed on the inner wall surface 12a of the porous structure 12, and the liquid crystal inside the holes is horizontal by applying a magnetic field. Oriented. Further, the vertical alignment treatment is performed on the surfaces of the upper and lower substrates 10 and 11 on which the porous structures 12 are arranged (the surfaces on which the porous structures 12 of the electrodes 20 are arranged).

  As a result, without forming an alignment film (for example, polyimide (PI) or a surfactant) on the wall surface of the through-hole 13 of the porous structure 12 having an ultrafine and three-dimensional structure, the liquid crystal in the hole is formed. By aligning, the filling amount of liquid crystal can be ensured and stable alignment can be achieved.

  By applying a voltage between the electrodes provided on the upper and lower substrates 10 and 11, the molecular orientation of the liquid crystal can be controlled and the optical characteristics can be changed. In addition, a sufficient optical distance L can be secured, the response speed can be greatly improved, and the liquid crystal filling amount can be secured. Accordingly, the response time of the liquid crystal optical element can be shortened, and the liquid crystal aberration correction element used for correcting the aberration generated at the time of recording / reproducing with the optical pickup can be put into practical use.

  In the alignment step, the direction of the magnetic field matches the thickness direction of the porous structure, whereby the liquid crystal in the holes can be aligned horizontally with respect to the wall surface, and more stable alignment can be achieved.

  In the porous structure forming step, an alumina porous structure having a certain thickness and a large number of circular through holes or non-through holes is obtained by anodizing the aluminum material. It can be easily formed.

  FIG. 15 is a partially enlarged conceptual view showing the configuration of the liquid crystal optical element 200 as the second embodiment. As shown in FIG. 15, the liquid crystal optical element 200 includes a glass substrate 10 on which a common electrode 20 is formed, a glass substrate 11 on which a first drive electrode 21 and a second drive electrode 22 are formed, and a porous structure. The body 12A and the liquid crystal 40 are included. The porous structure 12 </ b> A is a porous structure having a large number of non-through holes 14. As shown in the figure, the non-through hole 14 has a non-penetrated bottom surface 14a. It is in a position close to the lower surface of the porous structure 12A. The manufacturing method of the liquid crystal optical element 200 is the same as that of the liquid crystal optical element 100 described above except that the porous structure 12A of the non-through holes 14 is formed. Here, the overlapping description is omitted.

  In this example, the liquid crystal 40 is a nematic liquid crystal (Np liquid crystal) having a positive dielectric anisotropy in which the major axis of the molecule is directed in the direction of the electric field when a voltage is applied, and the non-through hole 14 of the porous structure 12A. Without forming an alignment film on the inner wall surface, the liquid crystal inside the hole is horizontally aligned with respect to the inner wall surface by applying a magnetic field in advance.

  Further, before the voltage is applied, the liquid crystals in the non-through holes of the porous structure 12A are aligned horizontally with respect to the inner wall surface, and the liquid crystals on the alignment treatment surface of the substrate 11 are aligned in a state perpendicular to the surface. ing. When a voltage is applied, the liquid crystal in the non-through holes 14 of the porous structure 12A changes from a horizontal alignment state to a vertical alignment state with respect to the inner wall surface by the voltage application. Further, the liquid crystal on the alignment treatment surface of the substrate 11 remains in the vertical alignment state.

  The liquid crystal optical element 200 having such a configuration can obtain the same effects as those of the first embodiment described above. Further, when anodizing treatment is performed on a high-purity aluminum material, processing of the aluminum material portion left by the anodizing treatment or back-etching processing for removing a portion of the hole that is not penetrated (the above-described figure) 10) is simplified.

  As a result, by aligning the liquid crystal in the holes without forming an alignment film on the wall surface of the non-through hole 14 of the porous structure 12A, the filling amount of the liquid crystal can be secured and stable alignment can be achieved.

  In the above-described embodiment, the case where the liquid crystal in the hole is aligned horizontally with respect to the wall surface by matching the direction of the magnetic field with the thickness direction of the porous structure 12 in the alignment step has been described. However, the present invention is not limited to this. For example, in the orientation step, the direction of the magnetic field is set to a direction perpendicular to the thickness direction of the porous structure, and the cell is rotated at a predetermined speed around the center of the cell in the magnetic field. Without forming an alignment film for aligning the liquid crystal on the wall surface of the through hole, the liquid crystal in the hole can be aligned perpendicular to the wall surface. In this case, the initial alignment state of the liquid crystal in the hole is radial as shown in FIG.

  Moreover, in embodiment mentioned above, although the porous structure 12 demonstrated what formed the anodic oxidation process with respect to a high purity aluminum material, it is not limited to this. For example, instead of the porous structure 12, an Si (silicon) material formed by etching may be used. Also, methods such as photolithography, vapor deposition, and hollow pipe bundling are conceivable.

  Moreover, in embodiment mentioned above, although many through-holes 13 of the porous structure 12 demonstrated what was formed in circular shape, it is not limited to this. For example, the through holes of the porous structure 12 can be formed in a hexagonal shape.

  In the above-described embodiment, black treatment may be performed on the upper surface or the lower surface of the porous structure 12 in order to reduce light leakage.

  Moreover, when the optical distance is sufficient and the hole diameter of the through hole of the porous structure is large, it is of course possible to use both the application of the organic alignment film and the alignment treatment using a magnetic field.

  The present invention relates to a liquid crystal optical element having an autofocus function or a macro-micro switching function or an optical disk device incorporated in a micro camera in a mobile phone, a personal digital assistant (PDA), a digital device or the like. It can be expected to be widely used, such as a liquid crystal optical element used to correct aberrations occurring during recording / reproducing in the field.

10, 11 Substrate 12, 12A Porous structure 12a Inner wall surface of porous structure 13 Through hole 14 Non-through hole 20 Common electrode 20h Heater electrode 21 First drive electrode 22 Second drive electrode V _○ Ground terminal V ₁ First drive terminal V ₂ Second drive terminal V _H heater terminal 32 Inlet 40 Liquid crystal 50 Sealing material 100,200 Liquid crystal optical element

Claims (5)

In a method of manufacturing a liquid crystal optical element having a plurality of substrates on which electrodes are formed and a porous structure sandwiched between the plurality of substrates and into which liquid crystal is injected,
An electrode forming step of forming an electrode on a substrate to be a base material;
Porous structure formation for forming a porous structure having a large number of through holes or non-through holes having a hole pitch of 100 to 1000 nm, a hole opening ratio s of 50 to 80%, and a thickness of 50 to 100 μm Process,
An assembly step of disposing the porous structure between the substrates to form a cell;
The cell is heated to a predetermined temperature without forming an alignment film on the wall of the through-hole or non-through-hole of the porous structure, and isotropic phase liquid crystal is injected into the cell. An alignment process for cooling the cell while applying a strong magnetic field, and a method for producing a liquid crystal optical element.   2. The alignment process according to claim 1, wherein in the alignment step, the direction of the magnetic field is set to a direction perpendicular to the thickness direction of the porous structure, and the cell is rotated at a predetermined speed around the center of the cell in the magnetic field. Manufacturing method of the liquid crystal optical element.   2. The method of manufacturing a liquid crystal optical element according to claim 1, wherein in the alignment step, a direction of the magnetic field coincides with a thickness direction of the porous structure.   4. The method for producing a liquid crystal optical element according to claim 1, wherein in the porous structure forming step, an aluminum material is subjected to anodization to form an alumina porous structure. . A liquid crystal optical element manufactured by the method for manufacturing a liquid crystal optical element according to claim 1,
A plurality of substrates on which electrodes are formed, and a porous structure having a large number of through-holes or non-through-holes sandwiched between the plurality of substrates and into which liquid crystal is injected,
The porous structure has a pore pitch of 100 to 1000 nm, a pore opening ratio s of 50 to 80%, and a thickness of 50 to 100 μm,
Without forming an alignment film for aligning liquid crystal on the wall surface of the through-hole or non-through hole of the porous structure, a liquid crystal injected into the through-hole or non-through hole by applying a magnetic field with a certain strength is applied to the wall surface. A liquid crystal optical element characterized by being aligned horizontally or vertically with respect to the liquid crystal optical element.