Liquid crystal optical element and manufacturing method of the same

Abstract

To provide a liquid crystal optical element allowing larger area.SOLUTION: A liquid crystal optical element comprises: a substrate; an alignment film arranged on the substrate; a first liquid crystal layer arranged on the alignment film; a second liquid crystal layer arranged on the alignment film and away from the first liquid crystal layer; and an organic film covering the first liquid crystal layer and the second liquid crystal layer and covering the alignment film around the first liquid crystal layer and the second liquid crystal layer. Each of the first liquid crystal layer and the second liquid crystal layer contains a plurality of liquid crystal molecules, and is cured with the alignment direction of the liquid crystal molecules being fixed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a liquid crystal optical element and a method for producing the same. [Background technology]

[0002] For example, a liquid crystal polarization grating using a liquid crystal material has been proposed. When light of wavelength λ is incident on such a liquid crystal polarization grating, it splits the incident light into zero-order diffracted light and first-order diffracted light. To realize such a liquid crystal polarization grating, it is necessary to orient the liquid crystal molecules in a complex manner within the plane. One type of orientation process for orienting the liquid crystal molecules is photo-alignment. Patterning by photo-alignment process is achieved by mask exposure or interference exposure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-522601 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the embodiment is to provide a liquid crystal optical element that can be made large in area and a method for manufacturing the same. [Means for solving the problem]

[0005] According to one embodiment, the liquid crystal optical element comprises: The liquid crystal display device comprises a substrate, an alignment film disposed on the substrate, a first liquid crystal layer disposed on the alignment film, a second liquid crystal layer disposed on the alignment film and spaced apart from the first liquid crystal layer, and an organic film that covers the first liquid crystal layer and the second liquid crystal layer, respectively, and covers the alignment film around the first liquid crystal layer and the second liquid crystal layer, wherein each of the first liquid crystal layer and the second liquid crystal layer includes a plurality of liquid crystal molecules and is hardened in a state in which the alignment direction of the liquid crystal molecules is fixed.

[0006] According to one embodiment, a method for producing a liquid crystal optical element includes the steps of: An alignment film is formed on a substrate, a plurality of first regions that have been aligned on the alignment film are formed, a liquid crystal material containing a liquid crystalline monomer is formed in the form of a film on the alignment film, the liquid crystal material that overlaps each of the plurality of first regions is hardened to form a liquid crystal layer, unhardened liquid crystal material is removed around each of the liquid crystal layers, and an organic film is formed that covers each of the liquid crystal layers and covers the alignment film around each of the liquid crystal layers. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a liquid crystal optical element 1 according to this embodiment. [Diagram 2] FIG. 2 is a diagram showing a cross section of the liquid crystal optical element 1 shown in FIG. 1 taken along the Y direction. [Diagram 3] FIG. 3 is a cross-sectional view that diagrammatically shows a first configuration example of the liquid crystal optical element 1. As shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view that diagrammatically shows a second configuration example of the liquid crystal optical element 1. As shown in FIG. [Diagram 5] FIG. 5 is a plan view showing a schematic example of an alignment pattern in the liquid crystal layer LC. [Figure 6] FIG. 6 is a diagram for explaining an example of a method for manufacturing the liquid crystal optical element 1 shown in FIG. [Figure 7] FIG. 7 is a diagram for explaining an example of a method for manufacturing the liquid crystal optical element 1 shown in FIG. [Figure 8] FIG. 8 is a diagram for explaining an alignment treatment by circularly polarized two-beam interference exposure. [Figure 9] FIG. 9 is a diagram for explaining an application example of the liquid crystal optical element 1. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the present embodiment will be described with reference to the drawings. Note that the disclosure is merely an example, and those who are skilled in the art can easily conceive of appropriate modifications while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, the drawings may be schematic in terms of width, thickness, shape, etc. of each part compared to the actual embodiment in order to make the explanation clearer, but they are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each figure, components that perform the same or similar functions as those described above with respect to the previous figures are given the same reference numerals, and duplicate detailed explanations may be omitted as appropriate.

[0009] In addition, in the drawings, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are shown as necessary for ease of understanding. The direction along the X-axis is called the X-direction or the first direction, the direction along the Y-axis is called the Y-direction or the second direction, and the direction along the Z-axis is called the Z-direction or the third direction. The plane defined by the X-axis and the Y-axis is called the XY plane, and the plane defined by the X-axis and the Z-axis is called the XZ plane. Viewing the XY plane is called planar view.

[0010] 1 is a diagram illustrating a liquid crystal optical element 1 according to the present embodiment. The liquid crystal optical element 1 includes a substrate 10, an alignment film 20, a plurality of liquid crystal layers LC spaced apart from each other, and an organic film 30.

[0011] The substrate 10 is a transparent substrate that transmits light, and is made of, for example, a transparent glass plate or a transparent synthetic resin plate. The substrate 10 may be made of, for example, a transparent synthetic resin plate having flexibility. The substrate 10 may have any shape. For example, the substrate 10 may be curved. The refractive index of the substrate 10 is, for example, greater than the refractive index of air.

[0012] In this specification, "light" includes visible light and invisible light. For example, the lower limit of the visible light range is 360 nm to 400 nm, and the upper limit of the visible light range is 760 nm to 830 nm. Visible light includes a first component (blue component) in a first wavelength band (e.g., 400 nm to 500 nm), a second component (green component) in a second wavelength band (e.g., 500 nm to 600 nm), and a third component (red component) in a third wavelength band (e.g., 600 nm to 700 nm). Invisible light includes ultraviolet light in a wavelength band shorter than the first wavelength band, and infrared light in a wavelength band longer than the third wavelength band. In this specification, "transparent" preferably means colorless transparency, however, "transparent" may also mean translucent or colored transparency.

[0013] The substrate 10 is formed in a flat plate shape along the XY 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 that are approximately parallel to the XY plane and face each other in the Z direction. The second main surface F2 is in contact with, for example, air, but may be covered with another thin film.

[0014] The alignment film 20 is disposed on the substrate 10. In the example shown in Fig. 1, the alignment film 20 is in contact with the first main surface F1.

[0015] A plurality of liquid crystal layers LC are disposed on an alignment film 20. In the example shown in Fig. 1, the plurality of liquid crystal layers LC are disposed in a matrix in the X direction and the Y direction. Each of the liquid crystal layers LC is a diffraction portion that diffracts incident light. The liquid crystal layer LC will be described in detail later, and has liquid crystal molecules aligned in a predetermined direction.

[0016] Here, this embodiment will be described with attention to two liquid crystal layers LC adjacent to each other in the Y direction in FIG.

[0017] Fig. 2 is a diagram showing a cross section along the Y direction of the liquid crystal optical element 1 shown in Fig. 1. In the following description, the liquid crystal layer on the left side in Fig. 2 is referred to as liquid crystal layer LC1, and the liquid crystal layer on the right side is referred to as liquid crystal layer LC2.

[0018] The alignment film 20 is disposed on the substrate 10. The alignment film 20 has a plurality of first regions A11 and A12 that have been subjected to an alignment treatment, and a second region A2 that surrounds these first regions A11 and A12. The second region A2 corresponds to a region that has not been subjected to an alignment treatment, or a region that has been subjected to an alignment treatment multiple times. The width of the second region A2 is, for example, about several μm to several cm. As will be described in detail later, the alignment treatment is a treatment that imparts an alignment regulating force that determines the alignment direction of the liquid crystal molecules contained in the liquid crystal layers LC1 and LC2 to the alignment film 20, and is, for example, a photo-alignment treatment that performs alignment treatment by light irradiation. Such an alignment film 20 may be referred to as a photo-alignment film. The alignment film 20 is formed of, for example, polyimide.

[0019] The liquid crystal layer LC1 corresponds to a first liquid crystal layer and is formed on the first region A11. The liquid crystal layer LC2 corresponds to a second liquid crystal layer and is formed on the first region A12. The liquid crystal layers LC1 and LC2 are positioned apart in the Y direction. No liquid crystal layer is present on the second region A2, and in the second region A2, the alignment film 20 is exposed from the liquid crystal layers LC1 and LC2.

[0020] The liquid crystal layers LC1 and LC2 have approximately the same thickness DLC. In one example, the thickness DLC is 1000 nm to 10 μm, and preferably 2000 nm to 6000 nm. The thickness DLC described here corresponds to the thickness when the liquid crystal layers LC1 and LC2 are each a single layer. Note that the liquid crystal layers LC1 and LC2 may be a multilayer structure in which multiple layers are laminated.

[0021] The organic film 30 is transparent and covers the liquid crystal layers LC1 and LC2, respectively, and also covers the alignment film 20 around the liquid crystal layers LC1 and LC2. The organic film 30 contacts, for example, the top surface US and the side surface SS of the liquid crystal layer LC1. In the second region A2, the organic film 30 contacts the alignment film 20. The top surface 30U of the organic film 30 is substantially flattened.

[0022] The organic film 30 is formed of, for example, an acrylic resin, an epoxy resin, a silicone resin, or the like. From the viewpoint of suppressing undesired refraction and reflection at the interfaces between the organic film 30 and the liquid crystal layers LC1 and LC2, it is desirable that the refractive index n30 of the organic film 30 is approximately equal to the refractive index nLC of the liquid crystal layers LC1 and LC2. In one example, it is desirable that the difference between the refractive index n30 and the refractive index nLC is 0.1 or less. In addition, from the viewpoint of suppressing undesirable refraction and reflection at the interface between the alignment film 20 and the organic film 30, the interface between the alignment film 20 and the liquid crystal layers LC1 and LC2, and the interface between the substrate 10 and the alignment film 20, it is desirable that the refractive indices of the substrate 10, the alignment film 20, the organic film 30, and the liquid crystal layers LC1 and LC2 are equivalent.

[0023] Next, a specific configuration example of the liquid crystal optical element 1 according to this embodiment will be described.

[0024] (First configuration example) Fig. 3 is a cross-sectional view diagrammatically illustrating a first configuration example of the liquid crystal optical element 1. Fig. 3 corresponds to a cross-sectional view including the liquid crystal layer LC1 of the liquid crystal optical element 1 illustrated in Fig. 2. The first configuration example corresponds to an example in which the liquid crystal layer LC1 functions as a reflective diffraction grating.

[0025] The liquid crystal layer LC1 has a plurality of liquid crystal structures LMS. The liquid crystal structure LMS has first liquid crystal molecules LM1 located on one end side thereof and second liquid crystal molecules LM2 located on the other end side thereof. The first liquid crystal molecules LM1 are adjacent to the alignment film 20, and the second liquid crystal molecules LM2 are adjacent to the top surface US.

[0026] The alignment direction of the first liquid crystal molecule LM1 is determined by the alignment restraining force of the alignment film 20. Each liquid crystal structure LMS can be regarded as a continuum in which a plurality of liquid crystal molecules, including the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2, are aligned in the Z direction. Therefore, by determining the alignment direction of the first liquid crystal molecule LM1, the alignment direction of the plurality of liquid crystal molecules LM aligned in the Z direction, including the second liquid crystal molecule LM2, is determined according to the alignment direction of the first liquid crystal molecule LM1. As a result, the plurality of liquid crystal molecules LM, including the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2 in each liquid crystal structure LMS, are each aligned in a predetermined direction in the XY plane.

[0027] The liquid crystal layer LC1 of this embodiment is cured with the alignment direction of the liquid crystal molecules LM, including the first liquid crystal molecules LM1 and the second liquid crystal molecules LM2, fixed. In other words, the alignment direction of the liquid crystal molecules LM is not controlled according to an electric field. For this reason, the liquid crystal optical element 1 does not include an electrode for alignment control. Such a liquid crystal layer LC1 is formed, for example, by applying energy such as light to a monomer to polymerize it.

[0028] In the configuration example 1 shown in Fig. 3, the liquid crystal layer LC1 has a cholesteric liquid crystal as a liquid crystal structure LMS. In Fig. 3, for the sake of simplicity, one liquid crystal molecule LM is shown as a representative liquid crystal molecule that faces the average alignment direction among a plurality of liquid crystal molecules positioned in the XY plane. The alignment direction of a plurality of first liquid crystal molecules LM1 aligned along the alignment film 20 changes continuously along the Y direction.

[0029] Focusing on one liquid crystal structure LMS, a plurality of liquid crystal molecules LM are stacked in a spiral shape along the Z direction while rotating. The alignment direction of the first liquid crystal molecules LM1 and the alignment direction of the second liquid crystal molecules LM2 are almost the same. The liquid crystal structure LMS has a helical pitch P. The helical pitch P indicates one period (360 degrees) of the helix.

[0030] The liquid crystal layer LC1 has a plurality of reflecting surfaces RS as indicated by dashed lines. In one example, the plurality of reflecting surfaces RS are substantially parallel to one another. The reflecting surfaces RS are inclined at an inclination angle φ with respect to the XY plane, and have a substantially planar shape extending in a fixed direction. The reflecting surfaces RS selectively reflect a portion of the light LTr of the incident light LTi according to Bragg's law, and transmit the remaining light LTt. The reflecting surfaces RS reflect the light LTr according to the inclination angle φ.

[0031] The reflecting surface RS here corresponds to a surface on which the liquid crystal molecules LM are aligned in the same direction, or a surface on which the spatial phase is aligned (an equiphase surface). The shape of the reflecting surface RS is not limited to a flat shape, and may be a concave or convex curved shape, and is not particularly limited.

[0032] The cholesteric liquid crystal, which is the liquid crystal structure LMS, reflects circularly polarized light having the same rotation direction as the cholesteric liquid crystal, among the light of a specific wavelength λ included in the selective reflection band Δλ. For example, when the rotation direction of the cholesteric liquid crystal is clockwise, it reflects right-handed circularly polarized light and transmits left-handed circularly polarized light among the light of the specific wavelength λ. Similarly, when the rotation direction of the cholesteric liquid crystal is counterclockwise, it reflects left-handed circularly polarized light and transmits right-handed circularly polarized light among the light of the specific wavelength λ.

[0033] If the helical pitch of the cholesteric liquid crystal is P, the refractive index of the liquid crystal molecule for extraordinary light is ne, and the refractive index of the liquid crystal molecule for ordinary light is no, then the selective reflection band Δλ of the cholesteric liquid crystal for perpendicularly incident light is generally expressed as "no*P~ne*P." In more detail, the selective reflection band Δλ of the cholesteric liquid crystal changes within the range of "no*P~ne*P" depending on the inclination angle φ of the reflecting surface RS, the incidence angle θi, and the like.

[0034] The liquid crystal layer LC1 may be a single layer or a multilayer. When the liquid crystal layer LC1 is a multilayer, liquid crystal layers with different helical pitches may be stacked, or liquid crystal layers with opposite helical directions may be stacked. When the liquid crystal layer LC1 is a single layer, the liquid crystal layer may have a continuously changing helical pitch.

[0035] (Second configuration example) Fig. 4 is a cross-sectional view diagrammatically illustrating a second configuration example of the liquid crystal optical element 1. Fig. 4 corresponds to a cross-sectional view including the liquid crystal layer LC1 of the liquid crystal optical element 1 illustrated in Fig. 2. The second configuration example corresponds to an example in which the liquid crystal layer LC1 functions as a transmission type diffraction grating.

[0036] The liquid crystal layer LC1 contains nematic liquid crystal with a uniform alignment direction. The alignment direction of the first liquid crystal molecules LM1 aligned along the substrate 10 changes continuously along the Y direction. When the liquid crystal layer LC1 is a multi-layered body as described above, it may be made of nematic liquid crystal partially twistedly aligned.

[0037] When the refractive index anisotropy or birefringence of the liquid crystal layer LC1 is Δn (the difference between the refractive index ne of the liquid crystal molecule for extraordinary light and the refractive index no for ordinary light), the thickness of the liquid crystal layer LC1 is DLC, and the wavelength of the diffracted light is λ, it is desirable that the retardation Δn·DLC of the liquid crystal layer LC1 be λ / 2.

[0038] Focusing on one liquid crystal structure LMS, the alignment direction of the first liquid crystal molecule LM1 and the alignment direction of the second liquid crystal molecule LM2 are substantially the same. Moreover, the alignment direction of other liquid crystal molecules LM between the first liquid crystal molecule LM1 and the second liquid crystal molecule LM2 is also substantially the same as the alignment direction of the first liquid crystal molecule LM1.

[0039] For such a liquid crystal optical element 1, light may be incident from the liquid crystal layer LC1 side or from the substrate 10 side. Here, the case where light is incident from the liquid crystal layer LC1 side will be described. After passing through the liquid crystal optical element 1, the incident light LTi is split into zeroth-order diffracted light LT0 and first-order diffracted light LT1. The diffraction angle θd0 of the zeroth-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.

[0040] Although the liquid crystal layer LC1 has been described with reference to FIGS. 3 and 4, the liquid crystal layer LC2 is also configured in the same manner as the liquid crystal layer LC1, and functions as a diffraction grating in the same manner as the liquid crystal layer LC1.

[0041] Fig. 5 is a plan view showing an example of an alignment pattern in the liquid crystal layer LC. Fig. 5 shows the alignment direction of the first liquid crystal molecule LM1 among the liquid crystal molecules contained in each liquid crystal structure of the liquid crystal layer LC overlapping the first region A1. There is no liquid crystal layer overlapping the second region A2. The alignment directions of the first liquid crystal molecules LM1 aligned along the Y direction are different from each other. That is, the spatial phase in the XY plane is different along the Y direction. For example, the alignment direction of each of the first liquid crystal molecules LM1 changes at a constant angle along the Y direction, that is, from left to right in the figure. Here, the amount of change in the alignment direction of the first liquid crystal molecules LM1 is constant along the Y direction, but may gradually increase or decrease.

[0042] On the other hand, the alignment directions of the first liquid crystal molecules LM1 aligned along the X direction are substantially the same, that is, the spatial phases in the XY plane are substantially the same in the X direction.

[0043] Next, an example of a method for manufacturing the liquid crystal optical element 1 will be described.

[0044] 6 and 7 are diagrams for explaining an example of a method for manufacturing the liquid crystal optical element 1 shown in FIG. 6, an alignment film 20 is formed on the first main surface F1 of the cleaned substrate 10. The alignment film 20 is made of, for example, polyimide.

[0045] 6, an alignment treatment is performed on the alignment film 20. The alignment treatment here, which will be described in detail later, is a process using interference exposure of two beams of ultraviolet light with a first circular polarization and ultraviolet light with a second circular polarization that is polarized in the opposite direction to the first circular polarization. Depending on the type of alignment film, light in the first wavelength band may be used instead of ultraviolet light.

[0046] When manufacturing a liquid crystal optical element 1 having an area larger than the area that can be exposed in one alignment process, the alignment film 20 is divided into a plurality of regions, and each region is aligned sequentially. The regions aligned in this manner by one exposure correspond to the first regions A11 and A12. The alignment direction of each of the first regions A11 and A12 is set to form the alignment pattern of the first liquid crystal molecules LM1 shown in FIG. 5. The regions that are not aligned (unexposed regions) around the first regions A11 and A12, or the regions that are aligned multiple times (multiple exposure regions) when forming the multiple first regions, correspond to the second region A2. When polyimide is used for the alignment film, imidization of the polyimide may be carried out either before or after the alignment treatment.

[0047] Next, in step 3 (S3) shown in the lower part of FIG. 6, a liquid crystal material M containing a liquid crystal monomer is applied onto the alignment film 20 to form a film. The liquid crystal material M is, for example, a liquid crystal monomer for forming a cholesteric liquid crystal dissolved in a solvent. Since the liquid crystal material M contacts the alignment film 20, the solvent has the property of dissolving the liquid crystal monomer and making the alignment film 20 insoluble. The liquid crystal material M is applied to the entire surface of the alignment film 20 so as to cover the alignment-treated first regions A11 and A12 and the second region A2. Thereafter, the substrate 10 on which the liquid crystal material M has been applied is placed in a chamber, and the pressure in the chamber is reduced to dry the solvent contained in the liquid crystal material M.

[0048] Thereafter, the liquid crystal material M is baked. As a result, among the liquid crystal molecules contained in the liquid crystal material M, the liquid crystal molecules overlapping the first regions A11 and A12 are aligned in a predetermined direction according to the alignment treatment direction of the alignment film 20. Meanwhile, the liquid crystal molecules overlapping the second region A2 are difficult to align in a desired direction, and may form alignment defects.

[0049] At this time, the liquid crystal material M is formed into a film in an uncured state.

[0050] Next, in step 4 (S4) shown in the upper part of FIG. 7, the liquid crystal material M is partially irradiated with ultraviolet rays UV to harden the liquid crystal material M. In this step, first, a mask MK having openings AP corresponding to the first regions A11 and A12 is prepared. Then, the mask MK is aligned so that the openings AP overlap the first regions A11 and A12. The mask MK may be in contact with the liquid crystal material M or may be spaced apart from the liquid crystal material M. Then, ultraviolet rays UV are irradiated through the mask MK. The ultraviolet rays UV transmitted through the openings AP are irradiated to the uncured liquid crystal monomer overlapping the first regions A11 and A12. As a result, the liquid crystal monomer is polymerized, hardening the liquid crystal material M, and liquid crystal layers LC1 and LC2 are obtained. The light-shielding portion LS of the mask MK overlaps the second region A2. Therefore, the ultraviolet rays UV irradiated to the mask MK are blocked by the light-shielding portion LS and are not irradiated to the uncured liquid crystal monomer overlapping the second region A2. Therefore, the liquid crystal material M overlapping the second region A2 is still in an uncured state.

[0051] Next, in step 5 (S5) shown in the middle of FIG. 7, a development process of the liquid crystal material M is performed. As a result, the uncured liquid crystal material M around the liquid crystal layers LC1 and LC2 is removed by the developer. By removing the liquid crystal material M, the second region A2 of the alignment film 20 is exposed. An organic solvent such as acetone or cyclohexanone is used as the developer. After the development process, the liquid crystal layers LC1 and LC2 are dried.

[0052] Next, in step 6 (S6) shown in the lower part of FIG. 7, an organic film 30 is formed to cover each of the liquid crystal layers LC1 and LC2. The organic film 30 covers the second region A2 of the alignment film 20 around each of the liquid crystal layers LC1 and LC2. The material for forming the organic film 30 is one that makes the alignment film 20 and the liquid crystal layers LC1 and LC2 insoluble, and may be a thermosetting resin or an ultraviolet-curing resin. Such an organic film 30 is formed by applying an uncured solution and then heating or irradiating it with light. The organic film 30 is formed to a thickness that makes the upper surface 30U almost flat. The organic film 30 only needs to cover at least the area where the liquid crystal layer LC is not present, and in that case, it is applied to a thickness equivalent to the thickness of the liquid crystal layer LC.

[0053] According to this embodiment, each of the liquid crystal layers LC overlapping the first regions A11 and A12 contains liquid crystal molecules that form a predetermined orientation pattern and functions as a diffraction grating. In this way, by arranging a plurality of liquid crystal layers LC functioning as diffraction gratings on the same substrate, it is possible to increase the area of ​​the liquid crystal optical element 1. Furthermore, since there is no liquid crystal layer LC overlapping the second region A2, it is possible to suppress undesired scattering of the liquid crystal layer LC caused by disturbance in the alignment of the liquid crystal molecules and clouding of the liquid crystal optical element 1. As a result, it is possible to suppress a decrease in the light utilization efficiency of the liquid crystal optical element 1.

[0054] FIG. 8 is a diagram for explaining an alignment treatment by circularly polarized two-beam interference exposure. A beam from a laser light source is expanded into a parallel light beam, and this light beam is split into two light beams by a polarizing beam splitter. After passing through a wave plate, each of the light beams is converted into a first right-handed circularly polarized light 61 and a second left-handed circularly polarized light 62. These first and second circularly polarized light 61 and 62 interfere with each other on the surface of the alignment film 20. In a region 63 on the alignment film 20 where the first and second circularly polarized light 61 and 62 interfere with each other, a spatially varying polarization pattern is recorded as an alignment treatment direction AD. An alignment restraining force along the alignment treatment direction AD is applied to the region 63. The first liquid crystal molecules LM1 of the liquid crystal layer LC are aligned along the alignment treatment direction AD.

[0055] (Examples) Fig. 9 is a diagram for explaining an application example of the liquid crystal optical element 1. The application example shown in Fig. 9 corresponds to an example in which the liquid crystal optical element 1 is a light guide element. The liquid crystal optical element 1 includes a substrate 10, an alignment film 20, liquid crystal layers LC1 and LC2, and an organic film 30. The liquid crystal layers LC1 and LC2 each function as a reflective diffraction grating as described with reference to Fig. 3.

[0056] Next, the optical action of the liquid crystal optical element 1 will be described. The light LTi incident on the liquid crystal optical element 1 includes, for example, visible light, ultraviolet light, and infrared light. 9, for ease of understanding, the light LTi is assumed to be incident on the substrate 10 substantially perpendicularly. The incident angle of the light LTi is not particularly limited. For example, the light LTi may be incident on the liquid crystal optical element 1 at a plurality of mutually different incident angles.

[0057] The light LTi enters the organic film 30 from the upper surface 30U and is incident on the liquid crystal layer LC1. The liquid crystal layer LC1 reflects light of some wavelengths of the light LTi toward the organic film 30 at the reflective surface RS and transmits light LTt of other wavelengths. The light LTt that has transmitted through the liquid crystal layer LC1 is transmitted through the alignment film 20 and the substrate 10.

[0058] The liquid crystal layer LC1 reflects a specific wavelength toward the organic film 30 at an approach angle θ that satisfies the optical waveguide condition in the organic film 30. The approach angle θ here corresponds to an angle equal to or greater than the critical angle θc at which total reflection occurs at the interface between the organic film 30 and air. The approach angle θ indicates the angle with respect to a perpendicular line perpendicular to the organic film 30.

[0059] When the substrate 10, the alignment film 20, the liquid crystal layers LC1 and LC2, and the organic film 30 have the same refractive index, these laminates can be a single optical waveguide. In this case, the light LTr reflected by the reflective surface RS is guided toward the side surface F3 while repeatedly being reflected at the interface between the substrate 10 and the air and the interface between the organic film 30 and the air.

[0060] As described above, according to this embodiment, it is possible to provide a liquid crystal optical element that can be made large in area.

[0061] Although several embodiments of the present invention have been described, these embodiments are merely illustrative and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0062] 1... liquid crystal optical element, 10... substrate, 20... alignment film, 30... organic film, LC... liquid crystal layer, LC1...first liquid crystal layer, LC2...second liquid crystal layer, A1...first area, A2...second area

Claims

1. A substrate; An alignment film disposed on the substrate; a first liquid crystal layer disposed on the alignment film; a second liquid crystal layer disposed on the alignment film and spaced apart from the first liquid crystal layer; an organic film that covers the first liquid crystal layer and the second liquid crystal layer, and that covers the alignment film around the first liquid crystal layer and the second liquid crystal layer; A liquid crystal optical element, wherein each of the first liquid crystal layer and the second liquid crystal layer includes a plurality of liquid crystal molecules, and is hardened with the alignment direction of the liquid crystal molecules fixed.

2. the alignment film has a plurality of first regions that are aligned and second regions that surround each of the first regions; Each of the first liquid crystal layer and the second liquid crystal layer is formed on the first region, The liquid crystal optical element according to claim 1 , wherein the second region is in contact with the organic film.

3. The liquid crystal optical element according to claim 1 , wherein each of the first and second liquid crystal layers comprises a cholesteric liquid crystal.

4. The liquid crystal optical element of claim 1 , wherein the first liquid crystal layer and the second liquid crystal layer each comprise a nematic liquid crystal.

5. The liquid crystal optical element according to claim 1 , wherein the refractive index of the organic film is equal to the refractive indexes of the first liquid crystal layer and the second liquid crystal layer.

6. An alignment film is formed on a substrate. forming a plurality of first regions that are aligned on the alignment film; forming a film of a liquid crystal material containing a liquid crystalline monomer on the alignment film; hardening the liquid crystal material overlying each of the plurality of first regions to form a liquid crystal layer; removing uncured liquid crystal material around each of said liquid crystal layers; A method for manufacturing a liquid crystal optical element, comprising forming an organic film that covers each of the liquid crystal layers and covers the alignment film around each of the liquid crystal layers.

7. The method according to claim 6 , wherein the liquid crystal material is cured by irradiating it with ultraviolet light using a mask having an opening corresponding to the first region.

8. The method for producing a liquid crystal optical element according to claim 6 , wherein the alignment treatment step comprises dividing the alignment film into a plurality of regions and sequentially performing the alignment treatment on each region.

9. The method for producing a liquid crystal optical element according to claim 6 , wherein the organic film is made of a material having a refractive index equivalent to that of the liquid crystal layer.

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