Liquid crystal optical element

Abstract

A liquid crystal optical element according to one embodiment comprises: a substrate having a first main surface; a plurality of structures aligned at a prescribed pitch in each of a plurality of first areas arranged in a first direction of the first main surface and in a second direction intersecting the first direction; and a liquid crystal layer arranged across the plurality of first areas and a second area surrounding each of the plurality of first areas. The liquid crystal layer comprises: first liquid crystal molecules arranged in the first areas between the adjacent structures and aligned along the structures; and second liquid crystal molecules having the long axes aligned in the same direction in the second area. Further, the liquid crystal layer is cured in a state in which the orientation directions of the first liquid crystal molecules and the second liquid crystal molecules are fixed.

Description

Technical Field

[0001] Embodiments of the present invention relate to liquid crystal optical elements.

Background Art

[0002] For example, a liquid crystal polarization grating using a liquid crystal material has been proposed. Such a liquid crystal polarization grating divides incident light into zero-order diffracted light and first-order diffracted light when light with a wavelength λ is incident. When realizing such a liquid crystal polarization grating, it is desired to improve productivity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the embodiment is to provide a liquid crystal optical element capable of suppressing undesired light scattering.

Means for Solving the Problems

[0005] According to one embodiment, a liquid crystal optical element includes a substrate having a first main surface, a plurality of structures arranged at a predetermined pitch in each of a plurality of first regions arranged in a first direction and a second direction intersecting the first direction on the first main surface, and a liquid crystal layer arranged over the plurality of first regions and second regions surrounding the plurality of first regions, A partition wall disposed on the first main surface in the second region, surrounding the first region, and formed of the same material as the structure; wherein the liquid crystal layer has, in the first region, first liquid crystal molecules arranged between adjacent ones of the structures and aligned along the structures, and, in the second region, second liquid crystal molecules having major axes aligned in the same direction, and is cured in a state where the alignment directions of the first liquid crystal molecules and the second liquid crystal molecules are fixed.and the width of the partition wall is larger than the width of the structure 。

Advantages of the Invention

[0006] According to one embodiment, it is possible to provide a liquid crystal optical element capable of suppressing undesired light scattering.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, this embodiment will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those modifications that can be easily conceived by those skilled in the art while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but this is merely an example and does not limit the interpretation of the present invention. Also, in this specification and each drawing, components that are the same as or perform similar functions to those described above with respect to the previously presented drawings may be given the same reference numerals, and detailed descriptions thereof may be omitted as appropriate.

[0009]

[0010] First, the basic configuration of the liquid crystal optical element 1 will be described. FIG. 1 is a plan view schematically showing a liquid crystal optical element 1. The liquid crystal optical element 1 includes a substrate 10 and a liquid crystal layer LC disposed on the substrate 10. The planar shape of the substrate 10 is a quadrilateral in the illustrated example, but may be other polygons, a circle, an ellipse, or the like. The liquid crystal optical element 1 has a plurality of first regions A1 and a lattice-shaped second region A2 surrounding these first regions A1. For example, the plurality of first regions A1 are formed in a matrix in the X direction and the Y direction. The first region A1 is a diffraction region that diffracts incident light. Such a first region (diffraction region) A1 is formed by a plurality of structures arranged at a predetermined pitch and liquid crystal molecules oriented in a predetermined direction by these structures. The structures will be described later. The liquid crystal layer LC is disposed over the plurality of first regions A1 and the second region A2.

[0011] In recent years, there has been an increasing demand for larger liquid crystal optical elements 1. When forming the structures of the first region A1 using a nanoimprint technique, if the mold used is enlarged as the size of the liquid crystal optical element 1 increases, it will lead to an increase in the cost of manufacturing the mold and an increase in the weight of the mold. Therefore, there is a method in which a mold smaller than the size of the substrate 10 is prepared, and the process of pressing this mold against the resin layer is performed while shifting the position of the mold. In one stamping process of pressing the mold against the resin layer, the structure of one first region A1 is formed. At this time, it is desirable that the first region A1 formed in the first stamping process and the first region A1 formed in the second stamping process are close to each other. However, if the mold is pressed against the same location multiple times, a structure of a desired shape cannot be formed. For this reason, a margin is generated between adjacent first regions A1. This margin corresponds to the second region A2. In this way, a large liquid crystal optical element 1 can be manufactured at low cost through a plurality of stamping processes using a mold smaller than the substrate size. On the other hand, if the liquid crystal molecules located in the second region A2 are randomly oriented, it may cause scattering of incident light and there is a possibility that the performance required of the liquid crystal optical element 1 cannot be exhibited.

[0012] Hereinafter, some embodiments of the liquid crystal optical element 1 that can suppress undesired light scattering in the second region A2 will be described with reference to the drawings.

[0013] (First Embodiment) FIG. 2 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the first embodiment. FIG. 2 corresponds to a cross-sectional view of the liquid crystal optical element 1 along the A-B line of the region surrounded by the dotted line in FIG. 1.

[0014] The liquid crystal optical element 1 according to the first embodiment includes a substrate 10, a thin film 11, a structure 20, a partition wall 30, and a liquid crystal layer LC.

[0015] The substrate 10 is a transparent substrate that transmits light, and is constituted by, for example, a transparent glass plate or a transparent synthetic resin plate. The substrate 10 may be constituted by, for example, a flexible transparent synthetic resin plate. The substrate 10 can take an arbitrary shape. For example, the substrate 10 may be curved. The refractive index of the substrate 10 is, for example, larger than the refractive index of air.

[0016] In this specification, "light" includes visible light and invisible light. For example, the lower limit wavelength of the visible light region is 360 nm or more and 400 nm or less, and the upper limit wavelength of the visible light region is 760 nm or more and 830 nm or less. Visible light includes a first component (blue component) in a first wavelength band (for example, 400 nm to 500 nm), a second component (green component) in a second wavelength band (for example, 500 nm to 600 nm), and a third component (red component) in a third wavelength band (for example, 600 nm to 700 nm). Invisible light includes ultraviolet rays in a wavelength band shorter than the first wavelength band and infrared rays in a wavelength band longer than the third wavelength band. In this specification, "transparent" preferably means colorless and transparent. However, "transparent" may be translucent or colored and transparent.

[0017] The substrate 10 is formed in a flat plate shape along the X-Y plane and has a first main surface F1 and a second main surface F2. The first main surface F1 and the second main surface F2 are surfaces substantially parallel to the X-Y plane and face each other in the Z direction. The second main surface F2 is in contact with air, for example, but may be covered with other thin films.

[0018] The thin film 11 is disposed on the first main surface F1 of the substrate 10. The thin film 11 may be formed of an organic material or an inorganic material, for example.

[0019] A plurality of structures 20 are disposed on the first main surface F1 in each of the first regions A1. The structure 20 here is a convex body extending in the Z direction from the thin film 11. Such a plurality of structures 20 have a function of defining the alignment direction of liquid crystal molecules contained in the liquid crystal layer LC, which will be described in detail later. The structure 20 is formed of the same organic material as the thin film 11 and is integrated with the thin film 11. The thin film 11 is disposed between adjacent structures 20 in the first region A1 and covers the first main surface F1. The plurality of structures 20 are arranged along the X direction at a predetermined first pitch P1. Although not shown in FIG. 2, the plurality of structures 20 are arranged along the Y direction at a second pitch P2 different from the first pitch P1.

[0020] Also, adjacent structures 20 along the X direction are arranged at a distance L1 apart. In one example, the distance L1 is 50 nm to 1500 nm, preferably 100 nm to 1000 nm.

[0021] The structure 20a located at the outermost periphery of the first region A1 and the structure 20a located at the outermost periphery of another adjacent first region A1 are arranged at a predetermined distance La apart in the X direction. Similarly, although not shown in FIG. 2, the structure 20a is also arranged at a predetermined distance apart in the Y direction. The second region A2 corresponds to the region between two adjacent structures 20a. That is, the distance La corresponds to the width of the second region A2. In one example, the distance La is from 100 μm to 5 mm, desirably 1 mm or less. The distance La is larger than a predetermined first pitch P1 of the structure 20.

[0022] In the X-Z plane, the structure 20 has, for example, a tapered cross-sectional shape along the Z direction. The structure 20 also has a top portion 20T and side surfaces 20S. The side surfaces 20S face each other in the X direction. Each of the side surfaces 20S is an inclined surface inclined with respect to the Z direction.

[0023] Each of the structures 20 has a substantially constant thickness D20 along the Z direction from the thin film 11. In one example, the thickness D20 is from 100 nm to 2000 nm, desirably from 300 nm to 1000 nm. The width WB1 is, for example, from 50 nm to 1500 nm, desirably from 100 nm to 1000 nm.

[0024] Also, the thickness D20 is equal to or larger than the distance L1 between adjacent structures 20 along the X direction. From the viewpoint of defining the alignment direction of the liquid crystal molecules, it is desirable that the distance L1 be small, and it is desirable that the thickness D20 be large. However, considering the productivity when forming the structure 20 by the manufacturing method using a mold described later, it is desirable that the distance L1 be large, and it is desirable that the thickness D20 be small.

[0025] The partition wall 30 is disposed on the first main surface F1 in the second region A2. The partition wall 30 here is a convex body extending in the Z direction from the thin film 11. Such a partition wall 30 is subjected to an alignment treatment so as to define the alignment direction of the liquid crystal molecules overlapping the partition wall 30 in the liquid crystal layer LC, which will be described in detail later. The partition wall 30 is formed of the same material as the thin film 11 and the structure 20 and is integrated with the thin film 11. In the example shown in FIG. 2, the partition wall 30 is separated from the structure 20a, but may be integrated with the structure 20a. The thin film 11 is disposed between the structure 20a and the partition wall 30 and covers the first main surface F1.

[0026] The partition wall 30 has a top portion 30T and side surfaces 30S. The side surfaces 30S face each other. The width WB2 of the partition wall 30 is the same as or smaller than the distance La and larger than the width WB1 of the structure 20. In one example, the width WB2 is from 100 μm to 5 mm. The partition wall 30 has a substantially constant thickness D30 along the Z direction from the thin film 11. The thickness D30 of the partition wall 30 is approximately the same as the thickness D20 of the structure 20, but may also be larger than the thickness D20.

[0027] The refractive indices of the thin film 11, the structure 20, and the partition wall 30 are equivalent to the refractive index of the substrate 10. Therefore, the light that reaches the interface between the substrate 10 and the thin film 11 hardly refracts.

[0028] The liquid crystal layer LC surrounds each of the plurality of structures 20 and the partition wall 30. The liquid crystal layer LC is in contact with the top portion 20T and the side surfaces 20S of the structure 20, and the top portion 30T and the side surfaces 30S of the partition wall 30. Also, the liquid crystal layer LC is in contact with the thin film 11 between adjacent structures 20 in the first region A1. Also, the liquid crystal layer LC is in contact with the thin film 11 between the structure 20a and the partition wall 30 in the second region A2.

[0029] The liquid crystal layer LC has a thickness DLC along the Z direction from the thin film 11. The thickness DLC of the liquid crystal layer LC is larger than the thickness D20 of the structure 20. In one example, the thickness DLC is from 1000 nm to 14000 nm, and preferably from 5000 nm to 12000 nm. Also, the thickness DLC of the liquid crystal layer LC is larger than the thickness D30 of the partition wall 30. The thickness DLC of the liquid crystal layer LC is larger than the distance L1 between adjacent structures 20.

[0030] The thickness DLC of the liquid crystal layer LC described here corresponds to the thickness when the liquid crystal layer LC is a single layer. Note that the liquid crystal layer LC may be a multilayer body in which a plurality of layers are stacked.

[0031] In the example shown in FIG. 2, in the Z direction, no other thin films or substrates overlap the liquid crystal layer LC. That is, the liquid crystal layer LC has a main surface F3 in contact with air. Note that the main surface F3 may be covered with other thin films such as a protective film.

[0032] The liquid crystal layer LC has a plurality of first liquid crystal structures LMS1 located in the first region A1 and a plurality of second liquid crystal structures LMS2 located in the second region A2. The first liquid crystal structure LMS1 has a plurality of first liquid crystal molecules LM1. Here, the first liquid crystal molecule LM1 located on the first main surface F1 side is defined as the liquid crystal molecule LM11, and the first liquid crystal molecule LM1 located on the main surface F3 side is defined as the liquid crystal molecule LM12. The second liquid crystal structure LMS2 has a plurality of second liquid crystal molecules LM2. Here, the second liquid crystal molecule LM2 located on the first main surface F1 side is defined as the liquid crystal molecule LM21, and the second liquid crystal molecule LM2 located on the main surface F3 side is defined as the liquid crystal molecule LM22.

[0033] Focusing on the first liquid crystal structure LMS1, the liquid crystal molecule LM11 is located between adjacent structures 20 and is close to the thin film 11. The liquid crystal molecule LM12 is located above the structure 20 along the Z direction and is close to the main surface F3. Also, the first liquid crystal structure LMS1 is located above the structure 20. The alignment direction of the liquid crystal molecule LM11 is defined by the adjacent structure 20. The relationship between the alignment direction and the structure 20 will be described later. The first liquid crystal structure LMS1 can be regarded as a continuum in which a plurality of first liquid crystal molecules LM1 including the liquid crystal molecules LM11 and LM12 are arranged in the Z direction. Therefore, when the alignment direction of the liquid crystal molecule LM11 is defined by the structure 20, the alignment directions of the plurality of first liquid crystal molecules LM1 arranged in the Z direction are defined according to the alignment direction of the liquid crystal molecule LM11. Thereby, the plurality of first liquid crystal molecules LM1 in the first liquid crystal structure LMS1 are horizontally aligned in a predetermined direction in the X-Y plane. The horizontal alignment here means that the long axis of the molecule has a direction horizontal to the first main surface F1.

[0034] Focusing on the second liquid crystal structure LMS2, the liquid crystal molecules LM21 are located above the partition wall 30 and close to the top portion 30T. The liquid crystal molecules LM22 are located above along the Z direction and close to the main surface F3. The alignment direction of the liquid crystal molecules LM21 is defined by the alignment restricting force of the aligned partition wall 30. The second liquid crystal structure LMS2 can be regarded as a continuum in which a plurality of second liquid crystal molecules LM2 including the liquid crystal molecules LM21 and LM22 are arranged in the Z direction. Therefore, when the alignment direction of the liquid crystal molecules LM21 is defined, the alignment directions of the plurality of second liquid crystal molecules LM2 arranged in the Z direction are defined according to the alignment direction of the liquid crystal molecules LM21. Thereby, the plurality of second liquid crystal molecules LM2 in the second liquid crystal structure LMS2 are uniformly horizontally aligned in the same direction in the X-Y plane. The alignment direction of the second liquid crystal molecules LM2 is not particularly limited as long as it is uniform in the same direction within the X-Y plane. In the example shown in FIG. 2, the second liquid crystal molecules LM2 are uniformly aligned in the X direction.

[0035] The liquid crystal layer LC is cured in a state where the alignment directions of the liquid crystal molecules including the first liquid crystal molecules LM1 and the second liquid crystal molecules LM2 are fixed. That is, the alignment direction of the liquid crystal molecules is not controlled according to an electric field. Therefore, the liquid crystal optical element 1 does not include an electrode for alignment control. Such a liquid crystal layer LC is formed, for example, by applying energy such as light to a monomer to polymerize it.

[0036] FIG. 3 is a plan view showing the partition wall 30 shown in FIG. 2. In FIG. 3, the illustration of the structure 20 is omitted, and the liquid crystal molecules LM21 in the liquid crystal layer LC are illustrated. The partition wall 30 is formed in a lattice shape having an extending portion 30X extending in the X direction and an extending portion 30Y extending in the Y direction, and surrounds each of a plurality of first regions A1 arranged along the X direction and the Y direction. The liquid crystal molecules LM21 overlap the extending portions 30X and 30Y and are aligned so that their major axes are substantially parallel to the X direction.

[0037] (Second Embodiment) FIG. 4 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the second embodiment. FIG. 4 corresponds to a cross-sectional view of the liquid crystal optical element 1 taken along line A-B shown in FIG. 1. The description of the configuration similar to that of the first embodiment described above is omitted by referring to the above description. In particular, the configuration of the first region A1 is the same as that of the first embodiment, and the description thereof is omitted.

[0038] The liquid crystal optical element 1 according to the second embodiment includes a substrate 10, a thin film 11, a plurality of structures 20, and a liquid crystal layer LC. The liquid crystal optical element 1 according to the second embodiment is different from the liquid crystal optical element 1 according to the first embodiment in that it does not include the partition wall 30.

[0039] In the second region A2, the thin film 11 covers the first main surface F1. The film thickness D11 of the thin film 11 is substantially constant between adjacent structures 20a. The liquid crystal layer LC surrounds each of the plurality of structures 20 in the first region A1 and is in contact with the thin film 11 between adjacent structures 20. The liquid crystal layer LC is also in contact with the thin film 11 in the second region A2.

[0040] In the second region A2, the liquid crystal molecules LM21 of the second liquid crystal structure LMS2 are close to the thin film 11. The liquid crystal molecules LM22 are located above along the Z direction and are close to the main surface F3.

[0041] The alignment direction of the liquid crystal molecules LM21 is defined by the alignment regulating force of the aligned thin film 11. Therefore, by defining the alignment direction of the liquid crystal molecules LM21, the alignment directions of the plurality of second liquid crystal molecules LM2 arranged in the Z direction are defined according to the alignment direction of the liquid crystal molecules LM21. As a result, the plurality of second liquid crystal molecules LM2 in the second liquid crystal structure LMS2 are uniformly horizontally aligned in the same direction in the X-Y plane.

[0042] (Third Embodiment) FIG. 5 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the third embodiment. FIG. 5 corresponds to a cross-sectional view of the liquid crystal optical element 1 taken along line A-B shown in FIG. 1. The description of the configuration similar to that of the above-described first embodiment is omitted by referring to the above description.

[0043] The liquid crystal optical element 1 according to the third embodiment includes a substrate 10, a plurality of structures 20, a partition wall 30, and a liquid crystal layer LC. The liquid crystal optical element 1 according to the third embodiment is different from the liquid crystal optical element 1 according to the first embodiment in that it does not include a thin film 11.

[0044] Each of the plurality of structures 20 is disposed in the first region A1 and is in contact with the first main surface F1. Here, the structure 20 is a convex body extending in the Z direction from the first main surface F1.

[0045] The partition wall 30 is disposed in the second region A2 and is in contact with the first main surface F1. Here, the partition wall 30 is a convex body extending in the Z direction from the first main surface F1. The partition wall 30 is formed of the same material as the structure 20.

[0046] The first main surface F1 is exposed between adjacent structures 20. Also, the first main surface F1 is exposed between the structure 20a and the partition wall 30.

[0047] The liquid crystal layer LC surrounds each of the plurality of structures 20 in the first region A1 and surrounds the partition wall 30 in the second region A2. Also, the liquid crystal layer LC is in contact with the first main surface F1 between adjacent structures 20 and is in contact with the first main surface F1 between the structure 20a and the partition wall 30.

[0048] The liquid crystal molecules LM11 of the first liquid crystal structure LMS1 are located between adjacent structures 20 and are close to the first main surface F1. The liquid crystal molecules LM12 are located above the structure 20 along the Z direction and are close to the main surface F3. Also, the first liquid crystal molecules LM1 are horizontally aligned along the structure 20. The liquid crystal molecules LM21 of the second liquid crystal structure LMS2 are close to the partition wall 30. The liquid crystal molecules 22 are located above along the Z direction and are close to the main surface F3. Also, the second liquid crystal molecules LM2 are uniformly horizontally aligned in the same direction.

[0049] Although not shown, the liquid crystal optical element 1 according to the third embodiment may not include the partition wall 30, similar to the second embodiment shown in FIG. 4. At this time, The first main surface F1 is exposed in the second region A2. The liquid crystal layer LC is in contact with the first main surface F1 in the second region A2. The liquid crystal molecules LM21 of the second liquid crystal structure LMS2 are located in the second region A2 and close to the first main surface F1. The liquid crystal molecules 22 are located above along the Z direction and close to the main surface F3. Also, the second liquid crystal molecules LM2 are uniformly horizontally aligned in the same direction.

[0050] (Fourth Embodiment) FIG. 6 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the fourth embodiment. FIG. 6 corresponds to a cross-sectional view of the liquid crystal optical element 1 taken along the line A-B shown in FIG. 1. The description of the configuration similar to the above-described first embodiment is omitted by referring to the above description.

[0051] The liquid crystal optical element 1 according to the fourth embodiment includes a substrate 10, a thin film 11, a plurality of structures 20, a partition wall 30, and a liquid crystal layer LC. The liquid crystal optical element 1 according to the fourth embodiment is different from the liquid crystal optical element 1 according to the first embodiment in that the second liquid crystal molecules LM2 are uniformly vertically aligned. Although not shown, the liquid crystal optical element 1 may not include at least one of the thin film 11 and the partition wall 30.

[0052] Here, the vertical alignment means that the long axis direction of the molecule has a direction (Z direction) perpendicular to the first main surface F1. The liquid crystal molecules LM21 of the second liquid crystal structure LMS2 are close to the upper side of the partition wall 30. The liquid crystal molecules LM22 are located above along the Z direction and close to the main surface F3. The alignment direction of the liquid crystal molecules LM21 is defined by the alignment regulating force of the aligned partition walls 30. By defining the alignment direction of the liquid crystal molecules LM21, the alignment directions of the plurality of second liquid crystal molecules LM2 arranged in the Z direction are defined according to the alignment direction of the liquid crystal molecules LM21. Thereby, the plurality of second liquid crystal molecules LM2 in the second liquid crystal structure LMS2 are uniformly aligned in the Z direction. Regarding the point where the second liquid crystal molecules LM2 are vertically aligned, it can also be applied to the second embodiment shown in FIG. 4 and the third embodiment shown in FIG. 5.

[0053] The liquid crystal optical element 1 may further include an alignment film 12 disposed between the first main surface F1 and the liquid crystal layer LC and in contact with the liquid crystal layer LC. Hereinafter, the liquid crystal optical element 1 according to some embodiments including the alignment film 12 will be described. The description of the same configurations as those in the above-described first embodiment, second embodiment, third embodiment, and fourth embodiment will be omitted by referring to the above description.

[0054] (Fifth Embodiment) FIG. 7 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the fifth embodiment. FIG. 7 corresponds to a cross-sectional view of the liquid crystal optical element 1 taken along the line A-B shown in FIG. 1.

[0055] The liquid crystal optical element 1 according to the fifth embodiment includes a substrate 10, a thin film 11, a plurality of structures 20, partition walls 30, an alignment film 12, and a liquid crystal layer LC.

[0056] The alignment film 12 has an alignment regulating force for aligning liquid crystal molecules in a desired direction. As the alignment film 12, a vertical alignment film or a horizontal alignment film can be applied. In each of the embodiments described below, the case where a horizontal alignment film is applied as the alignment film 12 will be described. The horizontal alignment film has an alignment regulating force in a predetermined direction in the X-Y plane. The alignment regulating force is generated by alignment treatment. As the alignment treatment, rubbing treatment or photo-alignment treatment can be applied. When a vertical alignment film is applied as the alignment film 12, the alignment treatment becomes unnecessary, so the process load can be reduced. At this time, it is preferable to reduce the polar angle anchoring energy at the interface between the alignment film 12 and the liquid crystal layer LC.

[0057] The alignment film 12 covers each of the plurality of structures 20 and is in contact with the top 20T and the side surface 20S of the structure 20. Further, the alignment film 12 covers the partition wall 30 and is in contact with the top 30T and the side surface 30S of the partition wall 30. Further, the alignment film 12 is in contact with the thin film 11 between adjacent structures 20. Further, the alignment film 12 is in contact with the thin film 11 between the structure 20a and the partition wall 30. In the example shown in FIG. 7, the alignment film 12 is not in contact with the first main surface F1 of the substrate 10.

[0058] The liquid crystal layer LC is in contact with the alignment film 12 in the first region A1 and the second region A2. As described above, the first liquid crystal molecules LM1 of the first liquid crystal structure LM1 are aligned in a predetermined direction by the structure 20. Therefore, the step of aligning the alignment film 12 in the first region A1 may be omitted, or the alignment film 12 in the first region may be omitted. On the other hand, the second liquid crystal molecules LM2 of the second liquid crystal structure LM2 are aligned in a predetermined direction by the alignment regulating force of the alignment film 12.

[0059] Although not shown, the liquid crystal optical element 1 according to the fifth embodiment may not include the thin film 11 as in the third embodiment shown in FIG. 5. In this case, the plurality of structures 20 and the partition wall 30 are in contact with the first main surface F1. The alignment film 12 covers each of the structure 20 and the partition wall 30, is in contact with the first main surface F1 between adjacent structures 20, and is also in contact with the first main surface F1 between the structure 20a and the partition wall 30.

[0060] (Sixth Embodiment) FIG. 8 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the sixth embodiment. FIG. 8 corresponds to a cross-sectional view of the liquid crystal optical element 1 taken along the line A-B shown in FIG. 1. The description of the configuration similar to that of the fifth embodiment described above is omitted by referring to the above description.

[0061] The liquid crystal optical element 1 according to the sixth embodiment includes a substrate 10, a thin film 11, a plurality of structures 20, an alignment film 12, and a liquid crystal layer LC. The liquid crystal optical element 1 according to the sixth embodiment is different from the liquid crystal optical element 1 according to the fifth embodiment in that it does not include a partition wall 30.

[0062] The thin film 11 covers the first main surface F1 of the second region A2. The alignment film 12 is in contact with the thin film 11 in the second region A2. The alignment film 12 is not in contact with the first main surface F1.

[0063] Although not shown, the liquid crystal optical element 1 according to the sixth embodiment may not include the thin film 11, similar to the third embodiment shown in FIG. 5. In this case, the plurality of structures 20 are in contact with the first main surface F1. The alignment film 12 covers the structures 20, is in contact with the first surface F1 between adjacent structures 20, and is also in contact with the first main surface F1 in the second region A2 (between adjacent structures 20a).

[0064] (Seventh Embodiment) FIG. 9 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the seventh embodiment. FIG. 9 corresponds to a cross-sectional view of the liquid crystal optical element 1 along the line A-B shown in FIG. 1. The description of the same configuration as that of the above-described fifth embodiment is omitted by referring to the above description.

[0065] The liquid crystal optical element 1 according to the seventh embodiment includes a substrate 10, a thin film 11, a plurality of structures 20, a partition wall 30, an alignment film 12, and a liquid crystal layer LC. The liquid crystal optical element 1 according to the seventh embodiment is different from the liquid crystal optical element 1 according to the fifth embodiment in that it includes the alignment film 12 only in the second region A2.

[0066] The alignment film 12 is disposed only on the top 30T of the partition wall 30. Note that the alignment film 12 may cover the side surface 30S of the partition wall 30. The alignment film 12 is not disposed in the first region A1, exposes the structures 20 and the thin film 11, and is not in contact with the first main surface F1. The liquid crystal layer LC surrounds each of the structures 20 in the first region A1 and is in contact with the top 20T and the side surface 20S of the structure 20. Further, the liquid crystal layer LC surrounds the partition wall 30 and is in contact with the side surface 30S of the partition wall 30. The liquid crystal layer LC is not in contact with the top 30T of the partition wall 30 and is in contact with the alignment film 12 disposed on the top 30T of the partition wall 30. Further, the liquid crystal layer LC is in contact with the thin film 11 between adjacent structures 20 and is in contact with the thin film 11 between the structure 20a and the partition wall 30.

[0067] Although not shown, the liquid crystal optical element 1 according to the seventh embodiment may not include the thin film 11, similar to the third embodiment shown in FIG. 5.

[0068] (Eighth Embodiment) FIG. 10 is a cross-sectional view schematically showing the liquid crystal optical element 1 according to the eighth embodiment. FIG. 10 corresponds to a cross-sectional view of the liquid crystal optical element 1 taken along the line A-B shown in FIG. 1. The description of the configuration similar to that of the above-described sixth embodiment is omitted by referring to the above description.

[0069] The liquid crystal optical element 1 in the eighth embodiment includes a substrate 10, a thin film 11, a plurality of structures 20, an alignment film 12, and a liquid crystal layer LC. The liquid crystal optical element 1 according to the eighth embodiment is different from the liquid crystal optical element 1 according to the sixth embodiment in that the alignment film 12 is provided only in the second region A2.

[0070] The alignment film 12 is disposed only on the thin film 11 in the second region A2. The alignment film 12 is not disposed in the first region A1, exposes the structure 20, and is not in contact with the first main surface F1 of the substrate 10. The liquid crystal layer LC surrounds each of the plurality of structures 20 and is in contact with the top 20T and the side surface 20S of the structure 20. Further, the liquid crystal layer LC is in contact with the thin film 11 between adjacent structures 20 and is in contact with the alignment film 12 in the second region A2 (between adjacent structures 20a).

[0071] Although not shown, the liquid crystal optical element 1 according to the eighth embodiment may not include the thin film 11, similar to the third embodiment shown in FIG. 5. In this case, the plurality of structures 20 are in contact with the first main surface F1. The alignment film 12 is disposed only on the first main surface F1 of the second region A2 (between adjacent structures 20a) and is in contact with the first main surface F1.

[0072] FIG. 11 is a plan view for explaining the alignment directions of the liquid crystal molecules LM11 and LM21 in the vicinity of the first main surface F1 of the liquid crystal optical element 1 shown in FIG. 1. FIG. 11 corresponds to an enlarged plan view of the liquid crystal optical element 1 of the region surrounded by the dotted line in FIG. 1.

[0073] The plurality of structures 20 have a plurality of first structures 21 and a plurality of second structures 22 in the first region A1. Note that the structure 20 is not disposed in the second region A2. The plurality of first structures 21 are arranged at intervals along the X direction. Further, the plurality of first structures 21 are formed to have substantially the same shape in plan view, and are formed, for example, in an arch shape protruding in the X direction. The plurality of second structures 22 are arranged at intervals along the Y direction. Further, the plurality of second structures 22 are formed to have substantially the same shape in plan view, and extend linearly, for example, along the X direction.

[0074] The liquid crystal molecules LM11 disposed between the first structures 21 are cured in a state where their major axes LX are aligned along the tangent line TL of the first structures 21. Further, the liquid crystal molecules LM11 disposed between the first structures 21 and the second structures 22 are cured in a state where their major axes LX are aligned along the extending direction of the second structures 22. In this way, the alignment direction of the liquid crystal molecules LM11 is defined by the structures 20 disposed in the first region A1. Further, the alignment directions of the plurality of first liquid crystal molecules LM1 arranged in the Z direction including the liquid crystal molecules LM12 are defined according to the alignment direction of the liquid crystal molecules LM11. Therefore, the liquid crystal molecules LM11 and the plurality of first liquid crystal molecules LM1 including the liquid crystal molecules LM12 are aligned in a predetermined direction in the X-Y plane, respectively.

[0075] The liquid crystal molecules LM21 arranged in the second region A2 are uniformly aligned in the same direction. The alignment direction of the liquid crystal molecules 21 is defined by the alignment regulating force applied to the surface in contact with the liquid crystal layer LC of the second region A2. The alignment regulating force of the second region A2 is applied to, for example, the partition wall 30. When the partition wall 30 is omitted, it is applied to the thin film 11. When both the partition wall 30 and the thin film 11 are omitted, it is applied to the first main surface F1. The alignment regulating force can be applied by an alignment process to be described in detail later. The alignment directions of the plurality of second liquid crystal molecules LM2 arranged in the Z direction and including the liquid crystal molecules LM22 are defined according to the alignment direction of the liquid crystal molecules LM21. Thereby, the liquid crystal molecules LM21 and the plurality of second liquid crystal molecules LM2 including the liquid crystal molecules LM22 are uniformly aligned in a predetermined direction in the X-Y plane, respectively.

[0076] Note that the second liquid crystal molecules LM2 arranged in the vicinity of the first region A1 may not be aligned in the same direction as the other second liquid crystal molecules LM2 due to the influence of the structure 20. However, in the liquid crystal optical element 1 according to each embodiment, this does not pose a problem.

[0077] (Example of the alignment pattern of the first liquid crystal molecules LM1) FIG. 12 is a plan view schematically showing an example of the alignment pattern of the first liquid crystal molecules LM1 in the liquid crystal layer LC of the first region A1. In FIG. 12, the alignment direction of the liquid crystal molecules LM11 close to the first main surface F1 among the first liquid crystal molecules LM1 included in the first liquid crystal structure LMS1 is shown. Also, in FIG. 12, the illustration of the structure 20 is omitted.

[0078] The liquid crystal molecules 11 are arranged along the X direction and the Y direction. The alignment directions of the liquid crystal molecules LM11 arranged along the X direction are substantially the same. That is, the spatial phase in the X-Y plane is substantially the same in the X direction. The alignment directions of the liquid crystal molecules LM11 arranged along the Y direction are different from each other. That is, the spatial phase in the X-Y plane is different along the Y direction. For example, the alignment direction of each of the liquid crystal molecules LM11 changes continuously by a predetermined angle along the Y direction (from left to right in FIG. 12). Here, the amount of change in the alignment direction of the liquid crystal molecules LM11 is constant along the Y direction, but may gradually increase or gradually decrease. Here, as shown in FIG. 12, the interval between a liquid crystal molecule LM11 having a certain alignment direction and a liquid crystal molecule LM11 having an alignment direction changed by 180 degrees with respect to that alignment direction is defined as the alignment pitch α.

[0079] For example, when the liquid crystal optical element 1 functions as a transmissive diffraction grating, the alignment pitch α is set to satisfy the following relationship when the wavelength of the diffracted light is λ, the incident angle is θi, and the diffraction angle of the first-order diffracted light is θd1.

[0080] α = λ / (sinθd1 - sinθi) The alignment pitch α is, for example, 3 μm or less.

[0081] Next, the layout of the structure 20 for realizing the alignment pattern shown in FIG. 12 will be described. FIG. 13 is a plan view showing an example of the layout of the structure 20.

[0082] As described above, the plurality of structures 20 include a first structure 21 and a second structure 22. The plurality of first structures 21 are each formed in an arch shape convex on the tip side of the arrow indicating the X direction in plan view. The plurality of first structures 21 are arranged at a first pitch P1 along the X direction and at a second pitch P2 different from the first pitch P1 along the Y direction. Here, the first pitch P1 is the distance between the vertices of two first structures 21 arranged in the X direction, and the second pitch P2 is the distance between the vertices of two first structures 21 arranged in the Y direction. In one example, the second pitch P2 is larger than the first pitch P1. Also, the second pitch P2 is larger than the distance La (the width of the second region A2) shown in FIG. 2. The second pitch P2 is equivalent to the alignment pitch α shown in FIG. 12. The second structure 22 is disposed between adjacent structures 21 in the Y direction and is arranged at a pitch P22 along the Y direction. In one example, the pitch P22 is equivalent to the second pitch P2, and the pitch P22 is equivalent to the alignment pitch α.

[0083] According to such an example of the layout, the alignment pattern of the liquid crystal molecules LM11 shown in FIG. 12 can be realized. Note that the number of the second structures 22 disposed between the first structures 21 adjacent in the Y direction may be two or more. Further, instead of the arch-shaped first structures 21, a plurality of linear structures having different extending directions may be applied.

[0084] Next, a specific configuration example of the first region A1 of the liquid crystal optical element 1 according to each embodiment will be described.

[0085] (First Configuration Example) FIG. 14 is a cross-sectional view schematically showing a first configuration example of the liquid crystal optical element 1. FIG. 14 corresponds to a cross-sectional view of the first region A1 of the liquid crystal optical element 1 taken along the C-D line shown in FIG. 11. The first configuration example corresponds to an example in which the liquid crystal optical element 1 functions as a transmissive diffraction grating. The liquid crystal layer LC has a nematic liquid crystal with the alignment directions aligned along the Z direction. The alignment directions of the plurality of liquid crystal molecules LM11 arranged along the first main surface F1 continuously change along the Y direction. Note that when the liquid crystal layer LC is a multilayer body as described above, a part thereof may be a twisted nematic liquid crystal.

[0086] When the refractive index anisotropy or birefringence of the liquid crystal layer LC is Δn (the difference between the refractive index ne for extraordinary light and the refractive index no for ordinary light of the liquid crystal molecules), the thickness of the liquid crystal layer LC is DLC, and the wavelength of the diffracted light is λ, it is desirable that the retardation Δn·DLC of the liquid crystal layer LC be λ / 2.

[0087] Focusing on one first liquid crystal structure LMS1, the alignment directions of the liquid crystal molecules LM11 and the alignment directions of the liquid crystal molecules LM12 are substantially the same. Also, the alignment directions of the other first liquid crystal molecules LM1 between the liquid crystal molecules LM11 and the liquid crystal molecules LM12 are also substantially the same as the alignment direction of the liquid crystal molecules LM11.

[0088] For such a liquid crystal optical element 1, light may be incident from the side of the liquid crystal layer LC, or light may be incident from the side of the substrate 10. Here, the case where light is incident from the side of the liquid crystal layer LC will be described. The incident light LTi is divided into a zero-order diffracted light LT0 and a first-order diffracted light LT1 after passing through the liquid crystal optical element 1. The diffraction angle θd0 of the zero-order diffracted light LT0 is equal to the incident angle θi of the incident light LTi. The diffraction angle θd1 of the first-order diffracted light LT1 is different from the incident angle θi.

[0089] (Second Configuration Example) FIG. 15 is a cross-sectional view schematically showing a second configuration example of the liquid crystal optical element 1. FIG. 15 corresponds to a cross-sectional view of the first region A1 of the liquid crystal optical element 1 along the C-D line shown in FIG. 1. The second configuration example corresponds to an example in which the liquid crystal optical element 1 functions as a reflective diffraction grating. The liquid crystal layer LC has a cholesteric liquid crystal. In FIG. 15, for simplicity of the drawing, one first liquid crystal molecule LM1 represents a liquid crystal molecule oriented in the average alignment direction among a plurality of liquid crystal molecules arranged in the X-Y plane. The alignment directions of the plurality of liquid crystal molecules LM11 arranged along the first main surface F1 continuously change along the Y direction.

[0090] Focusing on one first liquid crystal structure LMS1, the plurality of first liquid crystal molecules LM1 are stacked in a spiral shape along the Z direction while turning. The alignment directions of the liquid crystal molecules LM11 and the alignment directions of the liquid crystal molecules LM12 are substantially the same. The first liquid crystal structure LMS1 has a helical pitch P. The helical pitch P indicates one period (360 degrees) of the helix.

[0091] The liquid crystal layer LC has a plurality of reflecting surfaces 13 as shown by the dashed line. In one example, the plurality of reflecting surfaces 13 are substantially parallel to each other. The reflecting surface 13 is inclined with respect to the first main surface F1 and has a substantially planar shape extending in a certain direction. The reflecting surface 13 selectively reflects a part of the incident light LTi, i.e., the light LTr, and transmits the other light LTt according to Bragg's law. The reflecting surface 13 reflects the light LTr according to the inclination angle φ of the reflecting surface 13 with respect to the first main surface F1. In the example shown in FIG. 15, the helical pitch P is shown as the distance along the Z direction between the liquid crystal molecules LM11 and the liquid crystal molecules LM12. However, from the viewpoint of improving the reflectivity at the reflecting surface 13, it is desirable that the thickness DLC of the liquid crystal layer LC is 5 times or more of the helical pitch P, and more desirably 10 times or more.

[0092] The reflecting surface 13 here corresponds to a surface where the alignment directions of the first liquid crystal molecules LM1 are aligned, or a surface where the spatial phases are aligned (equiphase surface). Note that the shape of the reflecting surface 13 is not limited to a planar shape, and may be a concave or convex curved surface shape, and is not particularly limited. Further, a part of the reflecting surface 13 may have irregularities, the inclination angle φ of the reflecting surface 13 may not be uniform, or the plurality of reflecting surfaces 13 may not be regularly aligned. According to the spatial phase distribution of the first liquid crystal structure LMS1, a reflecting surface 13 having an arbitrary shape can be formed.

[0093] The cholesteric liquid crystal, which is the first liquid crystal structure LMS1, reflects circularly polarized light having the same turning direction as the turning direction of the cholesteric liquid crystal among the light of a predetermined wavelength λ included in the selective reflection band Δλ. For example, when the turning direction of the cholesteric liquid crystal is clockwise, among the light of the predetermined wavelength λ, the clockwise circularly polarized light is reflected and the counterclockwise circularly polarized light is transmitted. Similarly, when the turning direction of the cholesteric liquid crystal is counterclockwise, among the light of the predetermined wavelength λ, the counterclockwise circularly polarized light is reflected and the clockwise circularly polarized light is transmitted.

[0094] When the helical pitch of the cholesteric liquid crystal is denoted as P, the refractive index of the liquid crystal molecules for extraordinary light as ne, and the refractive index of the liquid crystal molecules for ordinary light as no, generally, the selective reflection band Δλ of the cholesteric liquid crystal for perpendicularly incident light is represented by "no*P~ne*P". In detail, the selective reflection band Δλ of the cholesteric liquid crystal varies according to the tilt angle φ of the reflection surface 13, the incident angle θi, etc. with respect to the range of "no*P~ne*P". Note that the liquid crystal layer LC may be a single layer or a multilayer. When the liquid crystal layer LC is a multilayer, liquid crystal layers with different helical pitches may be stacked, or liquid crystal layers with opposite helical winding directions may be stacked. Also, when the liquid crystal layer LC is a single layer, it may be a liquid crystal layer with a continuously changing helical pitch.

[0095] According to each of the embodiments described above, the first liquid crystal molecules LM1 arranged in the first region A1 are oriented along the structure 20, and the liquid crystal optical element 1 functions as a diffraction grating. Also, the second liquid crystal molecules LM2 arranged in the second region A2 are uniformly oriented in the same direction. For this reason, the second region A2 transmits the incident light as it is, or reflects the incident light in a predetermined direction. That is, undesired light scattering in the second region A2 can be suppressed. Also, clouding of the liquid crystal layer LC in the second region A2 is suppressed, and deterioration in the appearance of the liquid crystal optical element 1 can be suppressed.

[0096] (Method for manufacturing the liquid crystal optical element 1) Next, a method for manufacturing the liquid crystal optical element 1 according to the embodiment will be described. Here, an example of the method for manufacturing the liquid crystal optical element 1 according to the first embodiment shown in FIG. 2 will be described. FIG. 16 and FIG. 17 are diagrams for explaining an example of the method for manufacturing the liquid crystal optical element 1 according to the first embodiment shown in FIG. 2.

[0097] First, as shown in the upper part of FIG. 16, a transparent structural material 20M for forming the structure 20 is applied to the first main surface F1 of the substrate 10, and the solvent is removed to form a state in which the structural material 20M is temporarily cured. As the structural material 20M, an ultraviolet curable resin can be used. When an ultraviolet curable resin having the property of vertically aligning liquid crystal molecules is used as the structural material 20M, the alignment treatment described in detail later becomes unnecessary.

[0098] Next, as shown in the middle part of FIG. 16, the first stamping process is performed. First, a mold MD having concavo-convex portions formed according to the shape of the structure 20 is prepared. Then, the surface coated with the structural material 20M and the mold MD are arranged to face each other, the mold MD is overlapped with the structural material 20M, and ultraviolet rays are irradiated while applying pressure. As a result, among the structural material 20M, the portion where the mold MD is overlapped cures into a shape corresponding to the concavo-convex of the mold MD. In the example shown in FIG. 16, ultraviolet rays are irradiated in a state where the structural material 20M is interposed between the convex portion CV of the mold MD and the first main surface F1. Therefore, the first main surface F1 is covered with a thin film 11 made of the same material as the structure 20. Note that ultraviolet rays may be irradiated in a state where the convex portion CV of the mold MD is in contact with the first main surface F1. In this case, the formed structures 20 are separated from each other, and the first main surface F1 is exposed between the adjacent structures 20.

[0099] Thereafter, as shown in the lower part of FIG. 16, when the mold MD is removed, the structure 20 of the first region A1a is formed.

[0100] Next, as shown in the upper part of FIG. 17, the second stamping process is performed. That is, the mold MD is moved to a region different from the first region A1a, the surface coated with the structural material 20M and the mold MD are arranged to face each other, the mold MD is overlapped with the structural material 20M, and ultraviolet rays are irradiated while applying pressure.

[0101] Thereafter, as shown in the middle part of FIG. 17, when the mold MD is removed, the structure 20 of the second first region A1b and the partition wall 30 of the second region A2 are formed. Also, the first main surface F1 of the second region A2 is covered with a thin film 11 made of the same material as the structure 20. Note that the partition wall 30 may be removed to expose the thin film 11 in the second region A2, or the first main surface F1 of the second region A2 may be exposed. Further, the thin film 11 between adjacent structures 20 may be removed to expose the first main surface F1.

[0102] By repeating the same stamping process thereafter, the structure 20 can be formed on the first main surface F1 of the large-area substrate 10.

[0103] Although not shown, after forming the structure 20, an alignment film 12 may be formed at least in the second region A2 as in the fifth to eighth embodiments respectively shown in FIGS. 7 to 10. The alignment film 12 is formed, for example, as follows. First, an alignment film material is applied to a desired surface on the substrate 10 on which the structure 20 has been formed. Then, the alignment film material is cured by drying or the like to form the alignment film 12.

[0104] Next, an alignment process is performed at least in the second region A2. After the alignment process, as shown in the lower part of FIG. 17, a liquid crystal layer LC is formed across the first regions A1a and A1b and the second region A2. The liquid crystal layer LC is formed, for example, as follows. First, a liquid crystal material is applied across the first regions A1a and A1b and the second region A2. Then, light such as ultraviolet light is irradiated in a state where the liquid crystal molecules contained in the liquid crystal material are aligned in a predetermined direction in the first regions A1a and A1b and the second region A2 to cure the liquid crystal material and form the liquid crystal layer LC.

[0105] Hereinafter, the alignment directions of the liquid crystal molecules contained in the liquid crystal material, that is, the first liquid crystal molecules LM1 in the first regions A1a and A1b and the second liquid crystal molecules LM2 in the second region A2 will be described. The alignment direction of the first liquid crystal molecules LM1 is fixed as follows at a stage before curing the liquid crystal material. The liquid crystal molecules LM11 adjacent to the thin film 11 are horizontally oriented along the X-Y plane between adjacent structures 20, and their major axes are oriented along the tangents of the structures 20. The orientation direction of the first liquid crystal molecules LM1 overlapping the liquid crystal molecules LM11 in the Z direction is determined according to the orientation direction of the liquid crystal molecules LM11. The first liquid crystal molecules LM1 arranged above the structure 20 are oriented following the surrounding first liquid crystal molecules LM1. In the example shown in FIG. 17, the orientation direction of the first liquid crystal molecules LM1 overlapping the liquid crystal molecules LM11 is substantially the same as the orientation direction of the liquid crystal molecules LM11. However, when a chiral agent is added to the liquid crystal material, a plurality of first liquid crystal molecules LM1 overlap in the Z direction while rotating around the liquid crystal molecules LM11.

[0106] The orientation direction of the second liquid crystal molecules LM2 is fixed as follows at a stage before curing the liquid crystal material. The liquid crystal molecules LM21 adjacent to the top 30T of the partition wall 30 are uniformly oriented in the same direction by the orientation regulating force applied to the top 30T by the orientation treatment. The orientation direction of the second liquid crystal molecules LM2 overlapping the liquid crystal molecules LM21 in the Z direction is determined according to the orientation direction of the liquid crystal molecules LM21. In the example shown in FIG. 17, the orientation direction of the second liquid crystal molecules LM2 overlapping the liquid crystal molecules LM21 is substantially the same as the orientation direction of the liquid crystal molecules LM21. However, when a chiral agent is added to the liquid crystal material, a plurality of second liquid crystal molecules LM2 overlap in the Z direction while rotating around the liquid crystal molecules LM21.

[0107] In this way, according to the orientation directions of the liquid crystal molecules LM11 in the first region A1 and the liquid crystal molecules LM21 in the second region A2, the orientation directions of the first liquid crystal molecules LM1 and the second liquid crystal molecules LM2 are fixed respectively, and then the curing treatment of the liquid crystal material is performed.

[0108] Hereinafter, the orientation treatment of the liquid crystal optical element 1 of each embodiment will be described in detail. In the first to third embodiments without an alignment film, the alignment treatment is performed on at least any one of the following (a), (b), and (c). (a) When the liquid crystal optical element 1 includes the partition wall 30, the top portion 30T of the partition wall 30 (b) When the liquid crystal optical element 1 does not include the partition wall 30 but includes the thin film 11, the thin film 11 in the second region A2 (c) When the liquid crystal optical element 1 does not include the partition wall 30 and the thin film 11, the first main surface F1 of the second region A2 In the fifth to eighth embodiments including the alignment film 12, at least the alignment film 12 in the second region A2 is subjected to an alignment treatment.

[0109] As an example of the alignment treatment, a rubbing treatment can be mentioned. At this time, not only the second region A2 but also the first region A1 may be rubbed. When the first region A1 is rubbed, it is preferable that the azimuth anchoring energy at the interface between the surface subjected to the alignment treatment and the liquid crystal layer LC is smaller than the azimuth anchoring energy generated by the structure 20. Thereby, even when the first region A1 is rubbed, the first liquid crystal molecules LM1 are hardly affected by the rubbing treatment and are aligned along the structure 20. On the other hand, the second liquid crystal molecules LM2 located in the second region A2 are uniformly aligned in the rubbed direction.

[0110] Generally, each fiber of the rubbing cloth used for the rubbing treatment has a diameter of several to several tens of μm. The distance L1 between adjacent structures 20 is preferably smaller than the diameter of the fiber. By doing so, even when the first region A1 is rubbed, the fibers of the rubbing cloth do not enter between the adjacent structures 20 and are not rubbed. Therefore, the influence of the rubbing treatment on the alignment direction of the first liquid crystal molecules LM1 can be further suppressed. On the other hand, the distance La between the structures 20a located on the outermost periphery of the first region A1, that is, the width of the second region A2, is larger than the diameter of the fiber. For this reason, the rubbing treatment of the second region A2 is realized.

[0111] The alignment treatment of the alignment film 12 can also be performed by an optical alignment treatment. The photo-alignment treatment is realized, for example, by irradiating ultraviolet rays of linearly polarized light. The photo-alignment treatment is performed at least on the second region A2, but it may be performed not only on the second region A2 but also on the first region A1. When performing the photo-alignment treatment on the first region A1 and the second region A2, it is desirable to adjust the irradiation intensity of the ultraviolet rays so that the azimuth anchoring energy of the first region A1 is smaller than the azimuth anchoring energy of the second region A2. Further, when performing the photo-alignment treatment on the first region A1, it is preferable that the azimuth anchoring energy at the interface between the photo-aligned alignment film 12 and the liquid crystal layer LC is smaller than the azimuth anchoring energy generated by the structure 20. By doing so, the first liquid crystal molecules LM1 located in the first region A1 are hardly affected by the photo-alignment treatment and are aligned along the structure 20. On the other hand, the second liquid crystal molecules LM2 located in the second region A2 are uniformly aligned in the direction defined by the photo-alignment treatment. Alternatively, the upper part of the first region A1 may be shielded from light, and only the alignment film 12 disposed in the second region A2 may be subjected to the photo-alignment treatment. Thereby, the influence on the alignment direction of the first liquid crystal molecules LM1 due to the photo-alignment treatment can be suppressed.

[0112] According to the manufacturing method of the liquid crystal optical element 1 described above, the minute structure 20 can be easily formed using the mold MD having minute irregularities on the order of the wavelength. Such a structure 20 has a function of defining the alignment direction of the first liquid crystal molecules LM1 contained in the liquid crystal material applied to the first region A1. Further, since the surface of the second region A2 in contact with the liquid crystal layer LC has an alignment regulating force in one direction, the second liquid crystal molecules LM2 can be uniformly aligned in the same direction, and light scattering in the second region A2 can be suppressed. Therefore, a decrease in diffraction efficiency can be suppressed, and a liquid crystal optical element 1 with a good appearance can be mass-produced.

[0113] As described above, according to each embodiment, a liquid crystal optical element capable of suppressing undesired light scattering can be provided.

[0114] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0115] 1... Liquid crystal optical element 10... Substrate F1... First main surface A1... First region A2... Second region 11... Thin film 12... Alignment film 20... Structure 21... First structure 22... Second structure 20B... Bottom 20T... Top 20S... Side surface 30... Partition wall 30B... Bottom 30T... Top 30S... Side surface LC... Liquid crystal layer LMS1... First liquid crystal structure LMS2... Second liquid crystal structure LM1... First liquid crystal molecule LM2... Second liquid crystal molecule

Claims

1. A substrate having a first major surface, a plurality of structures arranged in a predetermined pitch in each of a plurality of first regions arranged in a first direction of the first major surface and a second direction intersecting the first direction, a liquid crystal layer disposed across the plurality of first regions and second regions surrounding the plurality of first regions respectively, a partition wall disposed on the first major surface in the second region, surrounding the first region and formed of the same material as the structure, and comprising: wherein the liquid crystal layer is in the first region, a first liquid crystal molecule disposed between adjacent structures and arranged along the structure, in the second region, a second liquid crystal molecule having respective major axes arranged in the same direction, and having: the first liquid crystal molecule and the second liquid crystal molecule are cured in a state where the alignment directions are fixed, a liquid crystal optical element, wherein the width of the partition wall is larger than the width of the structure.

2. The liquid crystal optical element according to claim 1, wherein the width of the second region is larger than the predetermined pitch.

3. further comprising a thin film disposed between the structures in the first region and covering the first major surface, the liquid crystal optical element according to claim 1, wherein the thin film is formed of the same material as the structure.

4. The liquid crystal optical element according to claim 1, further comprising an alignment film disposed between the liquid crystal layer and the substrate in the second region and in contact with the liquid crystal layer.

5. The liquid crystal optical element according to claim 4, further comprising an alignment film disposed between the liquid crystal layer and the substrate in the first region and in contact with the liquid crystal layer.

6. A substrate having a first major surface, a plurality of structures arranged in a predetermined pitch in each of a plurality of first regions arranged in a first direction of the first major surface and a second direction intersecting the first direction, a liquid crystal layer disposed across the plurality of first regions and second regions surrounding the plurality of first regions respectively, and comprising: the plurality of structures having a plurality of first structures in an arch shape, the plurality of first structures are arranged in a first pitch along the first direction and in a second pitch larger than the first pitch along the second direction, wherein the liquid crystal layer is in the first region, a first liquid crystal molecule disposed between adjacent structures and arranged along the structure, in the second region, a second liquid crystal molecule having respective major axes arranged in the same direction, and having: a liquid crystal optical element, wherein the first liquid crystal molecule and the second liquid crystal molecule are cured in a state where the alignment directions are fixed.

7. The plurality of structures further includes at least one second structure disposed between the first structures adjacent to each other in the second direction, The second structure extends linearly along the first direction. The liquid crystal optical element according to claim 6.

8. The first liquid crystal molecules located between the adjacent first structures are oriented such that their major axes are along the tangents of the first structures, The second liquid crystal molecules are oriented such that their major axes are in a direction substantially parallel or substantially perpendicular to the first main surface of the substrate. The liquid crystal optical element according to claim 6.

9. A substrate having a first main surface, A plurality of structures arranged in a predetermined pitch in each of a plurality of first regions arranged in a first direction of the first main surface and a second direction intersecting the first direction, A liquid crystal layer disposed over the plurality of first regions and a second region surrounding each of the plurality of first regions, the liquid crystal layer having a nematic liquid crystal with aligned alignment directions in the first regions, The liquid crystal layer, In the first region, first liquid crystal molecules disposed between the adjacent structures and arranged along the structures, In the second region, second liquid crystal molecules having their major axes aligned in the same direction, A liquid crystal optical element in which the alignment directions of the first liquid crystal molecules and the second liquid crystal molecules are fixed and cured.

10. The liquid crystal layer has a cholesteric liquid crystal in the first region. The liquid crystal optical element according to claim 1.

Images