Liquid crystal element and head-mounted display

Abstract

Provided are a liquid crystal element and a head-mounted display which are capable of switching polarization modulation and polarization non-modulation over a wide frequency band and a wide viewing angle, and which have excellent orientation stability. The liquid crystal element has a first substrate, a first weakly anchored horizontal alignment film, a liquid crystal layer containing dual-frequency driving liquid crystal molecules, a second weakly anchored horizontal alignment film, and a second substrate in this order, and has a comb electrode for generating an electric field to the liquid crystal layer on at least one of the first substrate and the second substrate. The dual-frequency driving liquid crystal molecules are twisted and oriented between the first substrate and the second substrate in a voltage-applied state and a voltage-unapplied state, and the twisting direction in the voltage-applied state is the same as the twisting direction in the voltage-unapplied state, and the twisting direction in the voltage-unapplied state is the same as the twisting direction in the voltage-unapplied state. The orientation direction of the dual-frequency drive liquid crystal molecules located in the center of the thickness direction of the liquid crystal layer is orthogonal or parallel to the extension direction of the comb electrodes.

Description

Technical Field

[0001] The following disclosure relates to a liquid crystal element and a head-mounted display. Background Art

[0002] In recent years, variable focus optical systems using liquid crystal elements such as Pancharatnam Berry (PB) lenses and switchable half wave plates (sHWP) have been proposed for head mounted displays, etc. sHWP is a device that can switch the polarization state of left and right circularly polarized light, which is achieved by liquid crystal.

[0003] As a technology related to a variable focus optical system, for example, a display device is disclosed in Patent Document 1, which includes a waveguide and a broadband adaptive lens assembly, wherein the waveguide is configured to guide light in a lateral direction parallel to an output surface of the waveguide, and further configured to externally combine the guided light through the output surface, and the broadband adaptive lens assembly is configured to internally combine and diffract light externally combined from the waveguide through the broadband adaptive lens assembly.

[0004] Patent Document 2 discloses a variable focus block including a sHWP and a plurality of liquid crystal lenses.

[0005] Patent document 3 discloses an optical element comprising a liquid crystal unit and a quarter wavelength film, wherein the liquid crystal unit comprises a first substrate, a liquid crystal layer and a second substrate, the liquid crystal layer contains liquid crystal molecules in a twisted orientation, the liquid crystal unit comprises electrodes, the electrodes are configured to be able to switch between a first state and a second state by applying a voltage to the liquid crystal layer, the switching between the first state and the second state is to control the polarization state of light incident on the liquid crystal unit, when circularly polarized light is incident on the liquid crystal unit, in the first state, the circularly polarized light is converted into a first linearly polarized light, and in the second state, the circularly polarized light is converted into a second linearly polarized light, and when linearly polarized light is incident on the liquid crystal unit, in the first state, the linearly polarized light is converted into a first circularly polarized light, and in the second state, the linearly polarized light is converted into a second circularly polarized light.

[0006] Patent document 4 discloses an optical element, comprising: a first liquid crystal unit having first liquid crystal molecules and a first electrode; and a second liquid crystal unit having second liquid crystal molecules and a second electrode, wherein the first electrode and the second electrode are configured to be able to switch between a first state and a second state, the first state being a state in which the second liquid crystal molecules are twistedly oriented and the first liquid crystal molecules are vertically oriented, and the second state being a state in which the first liquid crystal molecules are twistedly oriented and the second liquid crystal molecules are vertically oriented, and the azimuth angle of the orientation direction of the second liquid crystal molecules on the third substrate side in the first state and the azimuth angle of the orientation direction of the second liquid crystal molecules on the fourth substrate side are angles obtained by rotating the azimuth angle of the orientation direction of the first liquid crystal molecules on the first substrate side in the second state and the azimuth angle of the orientation direction of the first liquid crystal molecules on the second substrate side by 1 / 4 in the same direction. Prior art literature Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2021-501361 Patent Document 2: U.S. Patent No. 10379419 Patent Document 3: Japanese Patent Application Publication No. 2023-082644 Patent Document 4: Japanese Patent Application Publication No. 2023-121716 Summary of the invention Technical Problems to be Solved by the Invention

[0008] In the above-mentioned patent documents 1 and 2, there is a problem that it is difficult to realize a device structure that can switch between polarization modulation that converts the polarization state of left and right circularly polarized light with a wide bandwidth and a wide viewing angle and polarization non-modulation that does not convert the polarization state of left and right circularly polarized light. In the above-mentioned patent document 3, there is a problem that it is difficult to realize a device structure with excellent orientation stability. In the above-mentioned patent document 4, although a device with high reliability can be realized by stacking a twisted-oriented liquid crystal layer, there is a problem of increasing thickness or weight.

[0009] The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a liquid crystal element and a head mounted display which can switch between polarization modulation and polarization non-modulation in a wide band and a wide viewing angle and have excellent alignment stability. Technical solutions for solving technical problems

[0010] (1) The present invention provides a liquid crystal element, which comprises a first substrate, a first weakly anchored horizontal orientation film, a liquid crystal layer containing dual-frequency driven liquid crystal molecules, a second weakly anchored horizontal orientation film and a second substrate in sequence, wherein at least one of the first substrate and the second substrate comprises a comb-tooth electrode for generating an electric field to the liquid crystal layer, wherein the dual-frequency driven liquid crystal molecules are twisted and oriented between the first substrate and the second substrate in a voltage-applied state and a voltage-unapplied state, and the twisting direction in the voltage-applied state is the same as the twisting direction in the voltage-unapplied state, and the orientation direction of the dual-frequency driven liquid crystal molecules located at the center of the liquid crystal layer in the thickness direction is orthogonal to or parallel to the extension direction of the comb-tooth electrode.

[0011] (2) In addition, in some embodiments of the liquid crystal element of the present application, based on the structure of (1), the azimuthal anchoring energy of the first weakly anchored horizontal alignment film is less than 1×10 -4 J / m 2 .

[0012] (3) In addition, in some embodiments of the liquid crystal element of the present application, based on the structure of (1) above, the first weakly anchored horizontal orientation film contains a polymer having at least one of the groups represented by the following structural formula (P1) and the groups represented by the following structural formula (P2).

[0013] [Chemical formula 1]

[0014] [Chemical formula 2] (In the above structural formula, X has at least one of an ether group, an ester group and an amide group, R1, R2, R3 and R4 each independently represent a hydrocarbon group, and Y is a carbon atom or a silicon atom.)

[0015] (4) In addition, in some embodiments of the liquid crystal element of the present application, based on the configuration of (1), (2) or (3), the azimuthal anchoring energy of the second weakly anchored horizontal alignment film is less than 1×10 -4 J / m 2 .

[0016] (5) In addition, in the liquid crystal elements of certain embodiments of the present application, based on the construction of (1), (2), (3) or (4), the second weakly anchored horizontal orientation film contains a polymer having at least one of the groups represented by the following structural formula (P1) and the groups represented by the following structural formula (P2).

[0017] [Chemical formula 3]

[0018] [Chemical formula 4] (In the above structural formula, X has at least one of an ether group, an ester group and an amide group, R1, R2, R3 and R4 each independently represent a hydrocarbon group, and Y is a carbon atom or a silicon atom.)

[0019] (6) In addition, in the liquid crystal elements of certain embodiments of the present application, based on the construction of (1), (2), (3), (4) or (5), the first weakly anchored horizontal orientation film and the second weakly anchored horizontal orientation film do not have uniaxial orientation properties.

[0020] (7) In addition, in some embodiments of the liquid crystal element of the present application, based on the construction of (1), (2), (3), (4), (5) or (6), the in-plane phase difference between the first weakly anchored horizontal orientation film and the second weakly anchored horizontal orientation film is less than 1 nm.

[0021] (8) In addition, in the liquid crystal elements of certain embodiments of the present application, based on the construction of (1), (2), (3), (4), (5), (6) or (7), when no voltage is applied, the orientation direction of the dual-frequency driven liquid crystal molecules located at the center of the thickness direction of the liquid crystal layer is orthogonal to the extension direction of the comb-tooth electrode.

[0022] (9) In addition, in the liquid crystal elements of some embodiments of the present application, based on the configuration of (1), (2), (3), (4), (5), (6), (7) or (8), the comb-tooth electrode is only arranged on one of the first substrate and the second substrate.

[0023] (10) In addition, in some embodiments of the liquid crystal element of the present application, based on the configuration of (1), (2), (3), (4), (5), (6), (7), (8) or (9), the comb-tooth electrode on the first substrate side is arranged on the first substrate; and the comb-tooth electrode on the second substrate side is arranged on the second substrate, and the extension direction of the comb-tooth electrode on the first substrate side is parallel to the extension direction of the comb-tooth electrode on the second substrate side.

[0024] (11) In addition, in the liquid crystal elements of certain embodiments of the present application, based on the construction of (1), (2), (3), (4), (5), (6), (7), (8), (9) or (10), the ratio of the electrode width to the slit width of the comb-tooth electrode, i.e., the electrode width:slit width, is 1:2 to 1:6.

[0025] (12) In addition, in the liquid crystal elements of certain embodiments of the present application, based on the construction of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10) or (11), the ratio of the thickness of the liquid crystal layer to the slit width of the comb-tooth electrode, i.e., the thickness of the liquid crystal layer: the slit width, is 1:2.5 to 1:10.

[0026] (13) In addition, in some embodiments of the liquid crystal element of the present application, based on the structure of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11) or (12), a phase difference film is further provided on at least one of the side of the first substrate opposite to the liquid crystal layer and the side of the second substrate opposite to the liquid crystal layer.

[0027] (14) In addition, in some embodiments of the liquid crystal element of the present application, based on the structure of (13), the phase difference film has a first 1 / 4 wavelength film and a second 1 / 4 wavelength film in sequence from the side close to the liquid crystal layer.

[0028] (15) In addition, in the liquid crystal elements of some embodiments of the present application, based on the construction of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13) or (14), the horizontal orientation film of at least one of the first weakly anchored horizontal orientation film and the second weakly anchored horizontal orientation film contains at least two polymers, the at least two polymers are in contact with the comb-tooth electrode and have different refractive indices, and the polymer with the smallest refractive index among the at least two polymers is in contact with the liquid crystal layer.

[0029] (16) In addition, in some embodiments of the liquid crystal element of the present application, based on the construction of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14) or (15), the ratio of the azimuthal anchoring energy of the second weakly anchored horizontal orientation film to the azimuthal anchoring energy of the first weakly anchored horizontal orientation film is less than 10.

[0030] (17) In addition, in some embodiments of the liquid crystal element of the present application, based on the structure of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15) or (16), the first substrate or the second substrate has a curved flexible printed substrate, and the comb-tooth electrode is only arranged on the substrate located in the curved direction of the flexible printed substrate among the first substrate and the second substrate.

[0031] (18) In addition, other embodiments of the present invention provide a head-mounted display having a liquid crystal element described in (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16) or (17). Beneficial Effects

[0032] According to the present invention, it is possible to provide a liquid crystal element and a head mounted display which can switch between polarization modulation and polarization non-modulation in a wide band and a wide viewing angle and have excellent alignment stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic cross-sectional view of the liquid crystal element according to the first embodiment. Figure 2 It is a schematic perspective view of the liquid crystal element according to the first embodiment. Figure 3 This is a schematic diagram for explaining the alignment of liquid crystal molecules in the first state and the second state of the liquid crystal element according to the first embodiment. Figure 4 It is a diagram showing the axis orientation of the liquid crystal element according to the first embodiment. Figure 5 This is a schematic cross-sectional view showing an example of a weak anchor alignment film included in the liquid crystal element of the first embodiment. Figure 6 This is a diagram showing the Stokes plot of each layer in the first state of the liquid crystal element according to the first embodiment. Figure 7 It is a schematic cross-sectional view of a liquid crystal element according to Modification 1 of the first embodiment. Figure 8 It is a schematic cross-sectional view of a liquid crystal element according to Modification 2 of the first embodiment. Fig. 9 It is a schematic perspective view of a liquid crystal element according to Modification 3 of the first embodiment. Fig.10 It is a schematic cross-sectional view of a liquid crystal element according to Modification 3 of the first embodiment. Fig.11 It is a schematic cross-sectional view of a variable focus element having only a substrate on the incident side. Fig.12 It is a schematic perspective view of a liquid crystal element according to Modification 4 of the first embodiment. Fig.13 This is a graph showing the orientation direction of liquid crystal with respect to the thickness direction of the liquid crystal layer of the liquid crystal element according to the first embodiment. Fig.14 This is a graph showing the liquid crystal alignment azimuth with respect to the thickness direction of the liquid crystal layer of the liquid crystal element according to Modification 4 of the first embodiment. Fig.15 It is a schematic cross-sectional view of a variable focus element according to the second embodiment. Fig.16 It is a schematic cross-sectional view of a variable focus element according to Modification 1 of the second embodiment. Fig.17 This is a schematic diagram for explaining an example of a head mounted display according to the third embodiment. Fig.18 This is a schematic cross-sectional view of the liquid crystal element of Comparative Example 1. Fig.19 This is a schematic three-dimensional view of a liquid crystal element of Comparative Example 1. Fig. 20 This is a schematic diagram for explaining the alignment of liquid crystal molecules in the first state and the second state of the liquid crystal element of Comparative Example 1. Fig.21 This is a diagram showing the axis orientation of the liquid crystal element of Comparative Example 1. Fig. 22 This is a graph for explaining the voltage applied to the liquid crystal element of Comparative Example 1. Fig.23 This is a photograph showing the evaluation result of the alignment stability of the liquid crystal element of Comparative Example 1. Fig.24 This is a schematic diagram for explaining the alignment of liquid crystal molecules when the liquid crystal cell included in the liquid crystal element of Example 1 is heated to an isotropic phase state and then rapidly cooled. Fig.25 This is a schematic diagram for explaining the alignment of liquid crystal molecules in the first state and the second state of the liquid crystal element of Example 1. Fig.26 This is a diagram showing the axis orientation of the liquid crystal element of Example 1. Fig. 27 This is a photograph showing the evaluation results of the alignment stability of the liquid crystal element of Example 1. Fig.28 This is a diagram showing the axial orientation of the liquid crystal element of Example 4. Fig.29 This is a diagram showing the axial orientation of the liquid crystal element of Example 5. Fig.30 It is a cross-sectional schematic diagram of the variable focus element of Example 6. Fig.31 It is a schematic cross-sectional view of a variable focus element having only a substrate on the incident side. Fig.32 This is a schematic cross-sectional view illustrating the wiring of the variable focus element of Example 7. Fig.33 This is a diagram showing the axial orientation of the liquid crystal element of Example 9. DETAILED DESCRIPTION

[0034] Hereinafter, the embodiments of the present invention will be described. The present invention is not limited to the contents described in the following embodiments, and design changes can be appropriately made within the scope of the configuration of the present invention. In addition, in the following description, for the same parts or parts with the same functions, the same figure numerals are appropriately used between different drawings, and the repeated descriptions are appropriately omitted. The various modes of the present invention can also be appropriately combined within the scope of not departing from the gist of the present invention.

[0035] (Definition of terms) In this specification, the azimuth refers to the direction when the direction of the object is projected onto the substrate surface on the exit side of the liquid crystal element, and is expressed by the angle (azimuth) formed with the reference azimuth. Here, the reference azimuth (0°) is set to the direction when the orientation direction of the liquid crystal molecules on the first substrate side in the first state is projected onto the substrate surface on the exit side of the liquid crystal element. That is, the azimuth of the orientation direction of the liquid crystal molecules on the first substrate side in the first state is set to 0°. The azimuth is a positive angle in the counterclockwise direction from the reference azimuth, and a negative angle in the clockwise direction from the reference azimuth. Both the counterclockwise direction and the clockwise direction indicate the rotation direction when observing the liquid crystal element from the exit side. In addition, the azimuth indicates the value measured in the state of looking down at the liquid crystal element from the exit side.

[0036] In this specification, two straight lines (including axes, directions and orientations) are orthogonal to each other, which means that they are orthogonal when the liquid crystal element is viewed from the emission side. In addition, one of the two straight lines is tilted relative to the other straight line, which means that when the liquid crystal element is viewed from the emission side, the one straight line is tilted relative to the other straight line. In addition, the angle formed by the two straight lines means the angle formed by the one straight line and the other straight line when the liquid crystal element is viewed from the emission side.

[0037] In this specification, two straight lines (including axes, directions and orientations) are orthogonal, which means that the angle between them is 90°±5°, preferably 90°±1°, more preferably 90°±0.5°, and particularly preferably 90° (completely orthogonal). Two straight lines are parallel, which means that the angle between them is 0°±3°, preferably 0°±1°, more preferably 0°±0.5°, and particularly preferably 0° (completely parallel).

[0038] Refractive index (nx, ny, nz) "nx" is the refractive index in the direction of maximum refractive index in the plane (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane, and "nz" is the refractive index in the thickness direction. Unless otherwise specified, the refractive index refers to the value for light at 23°C and a wavelength of 550nm.

[0039] In-plane phase difference (Re) The in-plane phase difference (Re) refers to the in-plane phase difference of a layer (film) at a wavelength of 550 nm at 23°C unless otherwise specified. When the thickness of the layer (film) is d (nm), Re is calculated by Re = (nx-ny) × d. In this specification, unless otherwise specified, "phase difference" refers to the in-plane phase difference.

[0040] Retardation in thickness direction (Rth) The phase difference in the thickness direction (Rth) refers to the phase difference in the thickness direction of the layer (film) at 23°C, unless otherwise specified, at a wavelength of 550nm. When the thickness of the layer (film) is d (nm), Rth is determined by Rth = (nz-(nx+ny) / 2) × d. In this specification, the phase difference in the thickness direction is also referred to as "thickness phase difference".

[0041] In addition, in this specification, unless otherwise specified, the measurement wavelength of optical parameters such as the principal refractive index and phase difference is 550 nm.

[0042] The present invention is not limited to the following embodiments, and the design can be modified appropriately within the scope of the present invention.

[0043] (First Embodiment) Figure 1 It is a schematic cross-sectional view of the liquid crystal element according to the first embodiment. Figure 2 It is a schematic perspective view of the liquid crystal element according to the first embodiment. Figure 3 This is a schematic diagram for explaining the alignment of liquid crystal molecules in the first state and the second state of the liquid crystal element according to the first embodiment. Figure 4 It is a diagram showing the axis orientation of the liquid crystal element according to the first embodiment.

[0044] Figure 1 to Figure 4 The liquid crystal element 10 of the present embodiment shown in the figure has a first substrate 100, a first weakly anchored horizontal alignment film 411, a liquid crystal layer 300 containing dual-frequency driven liquid crystal molecules 310, a second weakly anchored horizontal alignment film 421, and a second substrate 200 in this order. The liquid crystal element 10 has a comb-tooth electrode 11 for generating an electric field (preferably for generating a lateral electric field) for the liquid crystal layer 300 on at least one of the first substrate 100 and the second substrate 200. The dual-frequency driven liquid crystal molecules 310 are twisted and oriented between the first substrate 100 and the second substrate 200 in a voltage-applied state and a voltage-unapplied state, and the twisting direction in the voltage-applied state is the same as the twisting direction in the voltage-unapplied state. The orientation direction of the dual-frequency driven liquid crystal molecules 310 located at the center of the thickness direction of the liquid crystal layer 300 is orthogonal or parallel to the extension direction 11A of the comb-tooth electrode 11. By adopting such a method, the orientation stability can be improved.

[0045] The liquid crystal element 10 of the present embodiment is a phase modulation element that can switch between polarization modulation for converting the polarization state of left and right circularly polarized light and polarization non-modulation for not converting the polarization state of left and right circularly polarized light. Here, the phase modulation element preferably has a high circular polarization light intensity in both the modulation state and the non-modulation state. In the case where a strongly anchored orientation film is configured as an orientation film between the first substrate and the liquid crystal layer, and between the second substrate and the liquid crystal layer, the liquid crystal molecules are easily oriented along the strongly anchored orientation film, so the initial orientation is stable. However, due to the orientation restriction force of the strongly anchored orientation film, the liquid crystal molecules are difficult to move, so, for example, the polarization modulation characteristics in the modulation state are good, but the polarization modulation characteristics in the non-modulation state are sometimes deteriorated. According to the design, the polarization modulation characteristics in the non-modulation state are good, but sometimes the polarization modulation characteristics in the modulation state are deteriorated. That is, it is difficult to achieve good polarization modulation characteristics in both the modulation state and the non-modulation state.

[0046] In order to solve this problem, it is conceivable to use a weakly anchored alignment film in both the first substrate and the second substrate. However, since the alignment regulating force of the weakly anchored alignment film is weak, it is generally difficult to improve the alignment stability.

[0047] The inventors of the present invention have so far believed that the effect of the comb-tooth electrodes provided on the substrates works near the "substrate interface", and therefore believed that the liquid crystal molecules located near the interface between the first substrate and the second substrate and the liquid crystal layer are preferably oriented parallel to or perpendicular to the extension direction of the comb-tooth electrodes. However, it is known that in the case of the present embodiment with weakly anchored alignment films on both substrates, the effect of the comb-tooth electrodes can be exerted on the liquid crystal molecules located near the center (bulk) of the liquid crystal layer, not the liquid crystal molecules located near the interface.

[0048] Therefore, in this embodiment, a first weakly anchored horizontal alignment film 411 and a second weakly anchored horizontal alignment film 421 are respectively arranged between the first substrate 100 and the liquid crystal layer 300 and between the second substrate 200 and the liquid crystal layer 300, and a dual-frequency driven liquid crystal molecule 310 is used, so that the orientation direction of the dual-frequency driven liquid crystal molecule 310 located in the center of the thickness direction of the liquid crystal layer 300 is arranged orthogonal to or parallel to the extension direction 11A of the comb-tooth electrode 11, so that the orientation of the dual-frequency driven liquid crystal molecule 310 (also called bulk dual-frequency driven liquid crystal molecule 310) located in the area away from the interface between the first substrate 100 and the liquid crystal layer 300 and the interface between the second substrate 200 and the liquid crystal layer 300 is stabilized, and good orientation stability is achieved. The liquid crystal element 10 of this embodiment is described in detail below.

[0049] like Figure 1 as well as Figure 2 As shown, the first substrate 100 has a first supporting substrate 110 and a comb-tooth electrode 11 in this order toward the liquid crystal layer 300. The second substrate 200 has a second supporting substrate 210 and does not have a comb-tooth electrode. The structure consisting of the components from the first substrate 100 to the second substrate 200 is also referred to as a liquid crystal cell 11C. That is, the first substrate 100, the first weakly anchored horizontal alignment film 411, the liquid crystal layer 300, the second weakly anchored horizontal alignment film 421, and the second substrate 200 constitute the liquid crystal cell 11C.

[0050] The comb-tooth electrode 11 is configured to be switchable between a first state and a second state by applying a voltage to the liquid crystal layer 300. In the first state, the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side are arranged in a first orientation direction 311A. In the second state, the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side are arranged in a second orientation direction 311B that is orthogonal to the first orientation direction 311A ​​when viewed from above.

[0051] The comb-tooth electrode 11 has a structure in which linear electrode portions 11E and slit portions 11S are alternately and repeatedly arranged. The electrode width of the comb-tooth electrode 11 refers to the width of each linear electrode portion 11E. The slit width of the comb-tooth electrode 11 refers to the width of each slit portion 11S. The pitch of the comb-tooth electrode 11 refers to the sum of the widths of a group of linear electrode portions 11E and slit portions 11S. The extension direction 11A of the comb-tooth electrode 11 means the direction in which the linear electrode portion 11E extends. Here, the comb-tooth electrode includes a dry electrode portion extending in a first direction and a plurality of linear electrode portions extending from the dry electrode portion in a second direction different from the first direction. Figure 1 to Figure 4 In the literature, the structure of the dry electrode portion of the comb-tooth electrode is omitted, and only the linear electrode portion is described.

[0052] In addition, in the present embodiment, an IPS (In-Plane Switching) electrode in which a strip-shaped common electrode and a strip-shaped pixel electrode are alternately arranged is used as the comb-tooth electrode 11, but the structure of the comb-tooth electrode 11 is not limited to this. For example, an FFS (Fringe Field Switching) electrode can also be preferably used. The FFS electrode, for example, includes a pixel electrode having a slit disposed therebetween on a planar common electrode. In addition, the FFS electrode may also include a common electrode having a slit disposed therebetween on a planar pixel electrode formed in a manner occupying each pixel area. The comb-tooth electrode 11 of the present embodiment is preferably an IPS electrode. By adopting such a method, the transmittance and circularly polarized light intensity can be improved.

[0053] In this specification, a voltage application state in which a voltage above a threshold value is applied between a pair of common electrodes and a pixel electrode is also referred to as “voltage application state” or “when voltage is applied”, and a no-voltage application state in which a voltage is not applied between a pair of common electrodes and a pixel electrode (including a case in which a voltage less than a threshold value is applied) is also referred to as “no-voltage application state” or “when voltage is not applied”.

[0054] In this embodiment, the comb-tooth electrode 11 is provided only on one of the first substrate 100 and the second substrate 200. By adopting such a method, the liquid crystal element 10 can be made into a simpler structure, and productivity can be improved. In addition, if the comb-tooth electrode 11 is arranged on both the first substrate 100 and the second substrate 200, ripples are likely to be generated, but in this embodiment, there is no such concern, and the in-plane uniformity of the optical characteristics can be improved.

[0055] The ratio of the electrode width of the comb-tooth electrode 11 to the slit width (electrode width: slit width) is preferably 1:2 to 1:6. By adopting such a method, the alignment uniformity can be further improved. Furthermore, the polarization degree of the emitted light can be improved. The ratio of the electrode width of the comb-tooth electrode 11 to the slit width (electrode width: slit width) is more preferably 1:2.5 to 1:5, and the ratio of the electrode width of the comb-tooth electrode 11 to the slit width (electrode width: slit width) is more preferably 1:3 to 1:4.

[0056] The ratio of the thickness of the liquid crystal layer 300 to the slit width of the comb-tooth electrode 11 (the thickness of the liquid crystal layer: the slit width) is preferably 1:2.5 to 1:10. By adopting such a method, the uniformity of the orientation can be further improved. In addition, the polarization degree of the emitted light can be improved. More preferably, the ratio of the thickness of the liquid crystal layer 300 to the slit width of the comb-tooth electrode 11 (the thickness of the liquid crystal layer: the slit width) is 1:3 to 1:8, and more preferably, the ratio of the thickness of the liquid crystal layer 300 to the slit width of the comb-tooth electrode 11 (the thickness of the liquid crystal layer: the slit width) is 1:4 to 1:6.

[0057] The comb-tooth electrode 11 has a pixel electrode as a comb-tooth electrode and a common electrode as a comb-tooth electrode. The pixel electrode and the common electrode can be formed, for example, by forming a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO) or an alloy thereof in a single layer or multiple layers by sputtering, and then patterning using photolithography.

[0058] The azimuth angle of the extension direction 11A of the comb-tooth electrode 11 is preferably 115° to 155°. This allows a modulation state to be achieved when no voltage is applied or when a low-frequency voltage is applied, and a non-modulation state to be achieved when a high-frequency voltage is applied.

[0059] The azimuth angle of the extension direction 11A of the comb-tooth electrode 11 is preferably 25° to 65°. This allows a non-modulation state to be achieved when no voltage is applied or when a low-frequency voltage is applied, and a modulation state to be achieved when a high-frequency voltage is applied.

[0060] like Figure 3 and Figure 4 As shown, the comb-tooth electrode 11 is configured to be able to switch between a first state and a second state by applying a voltage to the liquid crystal layer 300. In the first state, the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side are arranged in a first orientation direction 311A. In the second state, the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side are arranged in a second orientation direction 311B that is orthogonal to the first orientation direction 311A ​​when viewed from above.

[0061] The switching between the first state and the second state controls the polarization state of the light incident on the liquid crystal cell 11C. When circularly polarized light is incident on the liquid crystal cell 11C, in the first state, the circularly polarized light is converted into the first linearly polarized light, and in the second state, the circularly polarized light is converted into the second linearly polarized light having a polarization direction orthogonal to the polarization direction of the first linearly polarized light when viewed from above. When linearly polarized light is incident on the liquid crystal cell 11C, in the first state, the linearly polarized light is converted into the first circularly polarized light, and in the second state, the linearly polarized light is converted into the second circularly polarized light rotating in the direction opposite to the rotation direction of the first circularly polarized light. By adopting such a method, it is possible to switch between the state of emitting the circularly polarized light incident on the liquid crystal cell 10 without modulating it and the state of emitting the circularly polarized light incident on the liquid crystal cell 10 without modulating it in a wide band, while suppressing the thickness of the liquid crystal cell 10. That is, it is possible to realize a liquid crystal cell 10 that can switch between polarization modulation and polarization non-modulation in a wide band and can be made thinner.

[0062] In the liquid crystal element 10 of this embodiment having the liquid crystal unit 11C and the retardation film 500 described later, the first state is a polarization modulation state in which the polarization state of the left and right circularly polarized light is converted, and the second state is a polarization non-modulation state in which the polarization state of the left and right circularly polarized light is not converted. Here, the orientation direction of the dual-frequency driven liquid crystal molecules on the first substrate side refers to the orientation direction of the dual-frequency driven liquid crystal molecules at the interface on the first substrate side of the liquid crystal layer. Similarly, the orientation direction of the dual-frequency driven liquid crystal molecules on the second substrate side refers to the orientation direction of the dual-frequency driven liquid crystal molecules at the interface on the second substrate side of the liquid crystal layer.

[0063] The orientation direction of the dual-frequency driven liquid crystal molecules on the first substrate side and the orientation direction of the dual-frequency driven liquid crystal molecules on the second substrate side can be measured by measuring the liquid crystal unit through Axoscan (manufactured by Axometrics) and based on the output Mueller matrix. In addition, even if the software that fits the unit thickness and twist angle of the liquid crystal in Axoscan is used, the orientation direction of the dual-frequency driven liquid crystal molecules on the first substrate side and the orientation direction of the dual-frequency driven liquid crystal molecules on the second substrate side can be calculated.

[0064] The liquid crystal layer 300 contains dual-frequency driven liquid crystal molecules 310. By adopting such a method, two liquid crystal orientation states (i.e., a modulation state and a non-modulation state) can be switched using the comb-tooth electrodes 11 provided on only one substrate. In addition, by making the liquid crystal layer 300 contain dual-frequency driven liquid crystal molecules 310, even when the liquid crystal layer 300 is sandwiched by two weakly anchored orientation films (in this embodiment, a first weakly anchored horizontal orientation film 411 and a second weakly anchored horizontal orientation film 421), the orientation stability can be improved by performing a voltage application re-orientation treatment. In addition, when using ordinary liquid crystal molecules, although the orientation stabilization itself can be achieved, the modulation state and the non-modulation state cannot be switched only by the comb-tooth electrodes provided on one substrate.

[0065] The dual-frequency driven liquid crystal molecules 310 are liquid crystal molecules that behave as positive liquid crystal molecules with positive dielectric anisotropy (Δε) when a low-frequency voltage is applied, and behave as negative liquid crystal molecules with negative Δε when a high-frequency voltage is applied. In addition, a single compound can take the above action, and a mixture of multiple compounds can also take the above action. In this specification, both cases are referred to as dual-frequency driven liquid crystal molecules.

[0066] If dual-frequency liquid crystal is used, even if comb-tooth electrodes with different angles are not provided on the upper and lower substrates (the first substrate 100 and the second substrate 200), if one comb-tooth electrode is driven at a low frequency, the liquid crystal molecules are oriented in a direction perpendicular to the extension direction of the comb-tooth electrode, and if it is driven at a high frequency, the liquid crystal molecules are oriented in the extension direction of the comb-tooth electrode, so that the electrode structure can be simplified. Δε is represented by the following (Formula L). Δε=(dielectric constant of the long axis direction of the liquid crystal molecule)-(dielectric constant of the short axis direction of the liquid crystal molecule) (Formula L)

[0067] In this embodiment, the low frequency is, for example, 1 Hz to 1 kHz, and the high frequency is 10 kHz to 1 MHz. The frequency of positive and negative reversal of Δε is called a crossover frequency, which can be appropriately adjusted by the molecular structure of the liquid crystal material, the mixing ratio of the mixture, and the like.

[0068] The dual-frequency driven liquid crystal molecules 310 are twisted and oriented between the first substrate 100 and the second substrate 200. In each of the first state and the second state, the dual-frequency driven liquid crystal molecules 310 are twisted and oriented from the first substrate 100 side to the second substrate 200 side. The twisting direction of the dual-frequency driven liquid crystal molecules 310 in the first state is the same as the twisting direction of the dual-frequency driven liquid crystal molecules 310 in the second state. By adopting this method, good polarization modulation characteristics can be obtained in two states (non-modulation state and modulation state).

[0069] The twisting direction of the dual-frequency driven liquid crystal molecules 310 in the voltage applied state is the same as the twisting direction in the voltage-unapplied state. For example, if the twisting direction in the voltage applied state is right-handed, the twisting direction in the voltage-unapplied state is also right-handed, and if the twisting direction in the voltage applied state is left-handed, the twisting direction in the voltage-unapplied state is also left-handed.

[0070] The twisting orientation of the dual-frequency driven liquid crystal molecules 310 can be achieved, for example, by adding a chiral agent to the liquid crystal material. The chiral agent is not particularly limited, and a conventionally known chiral agent can be used. For example, S-811 (manufactured by Merck) can be used.

[0071] When viewed from above, the angle formed by the orientation direction (first orientation direction) 311A ​​of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side and the orientation direction 312A of the dual-frequency driven liquid crystal molecules 312 on the second substrate 200 side in the first state is preferably 57° or more and 82° or less, more preferably 63° or more and 75° or less, and further preferably 66° or more and 72° or less. By adopting such a method, polarization modulation and polarization non-modulation can be switched in a wider frequency band. Hereinafter, the angle formed by the orientation direction of the dual-frequency driven liquid crystal molecules on the first substrate side and the orientation direction of the dual-frequency driven liquid crystal molecules on the second substrate side when viewed from above is also referred to as a twist angle.

[0072] In a top view, the angle formed by the alignment direction (second alignment direction) 311B of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side in the second state and the alignment direction 312B of the dual-frequency driven liquid crystal molecules 312 on the second substrate 200 side is preferably 57° or more and 82° or less, more preferably 63° or more and 75° or less, and further preferably 66° or more and 72° or less. By adopting such a method, polarization modulation and polarization non-modulation can be effectively switched in a wide band. The torsion angle in the first state and the torsion angle in the second state may be the same or different, but are preferably the same.

[0073] In addition, the twist angle when no voltage is applied is preferably 67° to 92°, more preferably 73° to 85°, and further preferably 76° to 82°. Since the twist angle decreases as the voltage is applied, if the twist angle when no voltage is applied is set as described above, the twist angles of the first state and the second state can be set to the above-mentioned preferred ranges, so that polarization modulation and polarization non-modulation can be effectively switched over a wide bandwidth.

[0074] The alignment direction of the dual-frequency driven liquid crystal molecules 310 located at the center of the thickness direction of the liquid crystal layer 300 is also referred to as the average alignment direction of the liquid crystal. The average alignment direction of the liquid crystal is arranged in the middle of the alignment direction of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side and the alignment direction of the dual-frequency driven liquid crystal molecules 312 on the second substrate 200 side.

[0075] like Figure 3 and Figure 4 As shown, when no voltage is applied to the comb-tooth electrode 11 (also referred to as when the voltage is off), the alignment direction (liquid crystal average alignment direction) 310A of the dual-frequency driven liquid crystal molecules 310 located in the center of the thickness direction of the liquid crystal layer 300 is orthogonal to the extension direction 11A of the comb-tooth electrode 11. For example, when the liquid crystal is re-aligned while applying a low-frequency voltage when manufacturing the liquid crystal element 10, when no voltage is applied, the alignment direction of the dual-frequency driven liquid crystal molecules 310 located in the center of the thickness direction of the liquid crystal layer 300 is orthogonal to the extension direction 11A of the comb-tooth electrode 11. The voltage applied at this time needs to be lower than the crossover frequency of the dual-frequency driven liquid crystal molecules 310. For example, it is preferably 1 Hz or more and 1 kHz or less, and 1 V or more and 10 V or less. By performing this process, the average alignment direction 310A of the liquid crystal of the dual-frequency driven liquid crystal molecules 310 when no voltage is applied to the comb-tooth electrode 11 can be uniformly aligned in a state of being orthogonal to the extension direction 11A of the comb-tooth electrode 11.

[0076] In the present embodiment, the focus is on the relationship between the average liquid crystal alignment direction 310A and the extension direction 11A of the comb-tooth electrode 11, rather than the alignment directions of the dual-frequency-driven liquid crystal molecules 311 on the first substrate 100 side and the dual-frequency-driven liquid crystal molecules 312 on the second substrate 200 side. This is because the dual-frequency-driven liquid crystal molecules 310 located in a region away from the substrates (also referred to as bulk dual-frequency-driven liquid crystal molecules) are more easily affected by the extension direction 11A of the comb-tooth electrode 11 (the direction of the electric field E) than the dual-frequency-driven liquid crystal molecules 311 on the first substrate 100 side and the dual-frequency-driven liquid crystal molecules 312 on the second substrate 200 side.

[0077] For example, when the twist angle is set to 65° instead of 70°, the orientation direction of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side and the dual-frequency driven liquid crystal molecules 312 on the second substrate 200 side changes so that the angle formed by the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side and the dual-frequency driven liquid crystal molecules 312 on the second substrate 200 side becomes smaller, but the average orientation direction of the liquid crystal does not change. Although the same situation may occur depending on the concentration of the chiral agent added to the liquid crystal material, the average orientation direction of the liquid crystal does not change. Therefore, in this embodiment, the focus is on the average orientation direction 310A of the liquid crystal, rather than the orientation direction of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side and the orientation direction of the dual-frequency driven liquid crystal molecules 312 on the second substrate 200 side.

[0078] The material of the weakly anchored horizontal alignment film is not particularly limited, and known materials can be used (see paragraphs 0095 to 0101 of Japanese Patent Application No. 2022-065194). In addition, in order to improve reliability and productivity, it is also preferably composed of two or more polymers. In addition, in order to improve the panel strength (sealing tightness), it is also preferred to use a material having a polymerizable portion chemically bonded to the sealing material.

[0079] The first weakly anchored horizontal alignment film 411 preferably has an azimuthal anchoring energy of less than 1×10 -4 J / m 2 By adopting this method, the polarization modulation performance can be further improved. The second weakly anchored horizontal alignment film 421 preferably has an azimuth anchoring energy of less than 1×10 -4 J / m 2 By adopting this approach, the polarization modulation performance can be further improved.

[0080] The azimuthal anchoring energy can be calculated by various known methods, such as the torque balance method, the Nervoll method, calculation from the electric field response threshold, calculation based on the rotating magnetic field, etc. In addition, the azimuthal anchoring energy described in this specification is calculated using the calculation method based on the electric field response threshold. The lower limit of the azimuthal anchoring energy of the weakly anchored alignment film is not particularly limited, but the azimuthal anchoring energy of the weakly anchored alignment film is, for example, 1×10 -10 J / m 2 above.

[0081] The azimuthal anchoring energy of the first weakly anchored horizontal alignment film 411 is preferably 1×10 -10 J / m 2 More than and less than 1×10 -4 J / m 2 , more preferably 1×10 -8 J / m 2Above and 1×10 -5 J / m 2 By adopting such a method, it is possible to efficiently switch between polarization modulation and polarization non-modulation in a wide band.

[0082] The azimuthal anchoring energy of the second weakly anchored horizontal alignment film 421 is preferably 1×10 -10 J / m 2 More than and less than 1×10 -4 J / m 2 , more preferably 1×10 -8 J / m 2 Above and 1×10 -5 J / m 2 By adopting such a method, it is possible to efficiently switch between polarization modulation and polarization non-modulation in a wide band.

[0083] Preferably, the ratio of the azimuthal anchoring energy of the second weakly anchored horizontal orientation film 421 to the azimuthal anchoring energy of the first weakly anchored horizontal orientation film 411 (i.e., (azimuthal anchoring energy of the second weakly anchored horizontal orientation film 421) / (azimuthal anchoring energy of the first weakly anchored horizontal orientation film 411)) is less than 10. By adopting such a method, the orientation stability can be further improved. The ratio of the azimuthal anchoring energy of the second weakly anchored horizontal orientation film 421 to the azimuthal anchoring energy of the first weakly anchored horizontal orientation film 411 is more preferably less than 8, and further preferably less than 6.

[0084] The ratio of the azimuthal anchoring energy of the second weakly anchored horizontal alignment film 421 to the azimuthal anchoring energy of the first weakly anchored horizontal alignment film 411 is preferably 0.1 or more, more preferably 0.3 or more, and further preferably 0.5 or more.

[0085] The ratio of the azimuthal anchoring energy of the second weakly anchored horizontal alignment film 421 to the azimuthal anchoring energy of the first weakly anchored horizontal alignment film 411 is preferably 0.1 to 10, more preferably 0.3 to 8, and even more preferably 0.5 to 6.

[0086] The weakly anchored alignment film can be formed by an alignment treatment or without an alignment treatment. Specifically, the weakly anchored alignment film can be a rubbed alignment film, a photo-aligned film, or an untreated alignment film that has not undergone an alignment treatment.

[0087] The first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 are preferably untreated alignment films that have not been subjected to alignment treatment. That is, the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 preferably do not have uniaxial alignment. By adopting such a method, the alignment stability can be further improved.

[0088] It is preferred that the in-plane phase difference Re of the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 is less than 1 nm. By adopting such a mode, the alignment stability can be further improved.

[0089] The untreated alignment film is obtained, for example, by forming an alignment film material containing an alignment film polymer on a substrate. Examples of the alignment film polymer include polyimide and polyhexyl methacrylate. The alignment film polymer contained in the untreated alignment film may be one type or two or more types.

[0090] In addition, examples of the alignment film polymer contained in the untreated alignment film include polymers described in International Publication No. 2017 / 034023 in addition to polyimide and polyhexyl methacrylate, and among these, polyalkylene oxides such as polyethylene glycol and polypropylene glycol are preferred.

[0091] The horizontal alignment film has the function of aligning the dual-frequency driven liquid crystal molecules in the liquid crystal layer in the horizontal direction relative to the surface of the horizontal alignment film when no voltage is applied. Here, the dual-frequency driven liquid crystal molecules are aligned in the horizontal direction relative to the surface of the horizontal alignment film, which means that the pretilt angle of the dual-frequency driven liquid crystal molecules is greater than 0° and less than 5°, preferably greater than 0° and less than 2°, and more preferably greater than 0° and less than 1° relative to the surface of the horizontal alignment film. The pretilt angle of the dual-frequency driven liquid crystal molecules refers to the angle at which the long axis of the dual-frequency driven liquid crystal molecules is tilted relative to the main surface of the alignment film when no voltage is applied to the liquid crystal layer.

[0092] The first weakly anchored horizontal alignment film 411 preferably contains a polymer having at least one of a group represented by the following structural formula (P1) and a group represented by the following structural formula (P2). By adopting such a mode, the alignment stability can be further improved.

[0093] [Chemical formula 5]

[0094] [Chemical formula 6] (In the above structural formula, X has at least one of an ether group, an ester group and an amide group, R1, R2, R3 and R4 each independently represent a hydrocarbon group, and Y is a carbon atom or a silicon atom.)

[0095] The second weakly anchored horizontal alignment film 421 preferably contains a polymer having at least one of the group represented by the structural formula (P1) and the group represented by the structural formula (P2). By adopting this method, the polarization modulation performance and alignment stability can be further improved.

[0096] Preferably, the first weakly anchored horizontal orientation film 411 and the second weakly anchored horizontal orientation film 421 respectively contain a polymer having at least one of the groups represented by the above structural formula (P1) and the groups represented by the above structural formula (P2). By adopting such a method, the polarization modulation performance and orientation stability can be further improved. The structure of the polymer contained in the first weakly anchored horizontal orientation film 411 and the structure of the polymer contained in the second weakly anchored horizontal orientation film 421 may be the same or different. If they are the same, the anchoring energy of the first weakly anchored film and the second weakly anchored film can be the same, so it is more preferred. In addition, from the perspective of productivity, it is also preferred to be the same.

[0097] It is preferable that the light incident on the liquid crystal element 10 is circularly polarized light. By adopting such a mode, it is possible to realize the liquid crystal element 10 capable of switching the polarization state of circularly polarized light.

[0098] Figure 5 1 is a cross-sectional schematic diagram showing an example of a weakly anchored alignment film provided in the liquid crystal element of the first embodiment. At least one of the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 (the first weakly anchored horizontal alignment film 411 in this embodiment) is preferably in contact with the comb electrode 11 and contains at least two polymers having different refractive indices, and the polymer with the smallest refractive index among the at least two polymers is in contact with the liquid crystal layer 300.

[0099] The refractive index of the transparent electrode (comb-tooth electrode 11) is large relative to the glass substrate (the first supporting substrate 110 and the second supporting substrate 210) and the liquid crystal layer 300, and therefore, the optical loss caused by unnecessary diffraction, haze, unnecessary reflection, etc. is large. However, by adjusting the refractive index of the alignment film material and coating it on the surface of the transparent electrode (comb-tooth electrode 11), the difference in refractive index between the layers can be reduced and their optical losses can be reduced. That is, the horizontal alignment film of at least one of the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 (the first weakly anchored horizontal alignment film 411 in this embodiment) is in contact with the comb-tooth electrode 11 and contains at least two polymers with different refractive indices. By making the polymer with the smallest refractive index of the at least two polymers in contact with the liquid crystal layer 300, the difference in refractive index between the layers can be reduced and the optical loss can be reduced.

[0100] like Figure 1As shown, the liquid crystal element 10 of this embodiment has a phase difference film 500 on at least one side of the first substrate 100 opposite to the liquid crystal layer 300 and the second substrate 200 opposite to the liquid crystal layer 300. The phase difference film 500 can be arranged on both sides of the first substrate 100 opposite to the liquid crystal layer 300 and the second substrate 200 opposite to the liquid crystal layer 300, but is preferably arranged on one side. By adopting such a method, the productivity of the liquid crystal element 10 can be improved.

[0101] The phase difference film 500 is arranged on the side of the first substrate 100 opposite to the liquid crystal layer 300 and on the side of the second substrate 200 opposite to the liquid crystal layer 300, and the phase difference film 500 has a first 1 / 4 wavelength film 12 and a second 1 / 4 wavelength film 13 in order from the side close to the liquid crystal layer 300. By adopting such a method, polarization modulation and polarization non-modulation can be switched in a wider band. Hereinafter, a method in which the liquid crystal element 10 has a liquid crystal unit 11C, a first 1 / 4 wavelength film 12, and a second 1 / 4 wavelength film 13 in order from the incident side to the exit side is described.

[0102] When no voltage is applied to the comb-tooth electrode 11 or when the frequency is lower than the crossover frequency of the dual-frequency driven liquid crystal molecules 310 (also referred to as low-frequency driving), the circularly polarized light (e.g., right circularly polarized light) incident on the liquid crystal cell 11C becomes the first linearly polarized light after passing through the liquid crystal cell 11C. Moreover, the first linearly polarized light passes through the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13, thereby being converted into circularly polarized light (e.g., left circularly polarized light) with a polarization state different from that of the circularly polarized light incident on the liquid crystal cell 11C in a wide band. In this way, in the first state, the circularly polarized light incident on the liquid crystal element 10 is converted into circularly polarized light with a different polarization state (e.g., right circularly polarized light is converted into left circularly polarized light), and the polarization modulation of the outgoing light is realized in a wide band.

[0103] In addition, when the voltage of the comb-tooth electrode 11 is applied, the circularly polarized light (for example, right circularly polarized light) incident on the liquid crystal unit 11C becomes a second linearly polarized light having a polarization direction orthogonal to the polarization direction of the first linearly polarized light when viewed from above after passing through the liquid crystal unit 11C. That is, the second state can be achieved. Moreover, the second linearly polarized light passes through the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13, and is emitted over a wide band in a state of circularly polarized light (for example, right circularly polarized light) having the same polarization state as the circularly polarized light incident on the liquid crystal unit 11C. In this way, in the second state, the polarization non-modulation emitted while the circularly polarized light incident on the liquid crystal element 10 maintains the same polarization state (for example, maintains the state of right circularly polarized light) is achieved over a wide band.

[0104] In addition, in the present embodiment, the liquid crystal cell 11C, the first quarter wavelength film 12, and the second quarter wavelength film 13 are sequentially provided from the incident side to the exit side, but the stacking order thereof may be reversed. Specifically, the second quarter wavelength film 13, the first quarter wavelength film 12, and the liquid crystal cell 11C may be sequentially provided from the incident side to the exit side. In this case, in the first state, the circularly polarized light incident on the liquid crystal element 10 is converted into circularly polarized light of a different polarization state (for example, right circularly polarized light is converted into left circularly polarized light) and the polarization modulation of the exit is realized in a wide band, and in the second state, the circularly polarized light incident on the liquid crystal element 10 maintains the same polarization state (for example, the state of maintaining right circularly polarized light) and the polarization non-modulation of the exit is realized in a wide band. In addition, in the case where the stacking order is reversed, the lag axis 12A of the first quarter wavelength film 12 and the lag axis 13A of the second quarter wavelength film 13 are appropriately adjusted.

[0105] Figure 6 This is a diagram showing the Stokes plot of each layer in the first state of the liquid crystal element according to the first embodiment. Figure 6 The polarization state (the role of each layer) when transmitting each layer in the first state is shown. Figure 6 The principle of polarization modulation of the liquid crystal element 10 according to the first embodiment will be described in detail using the Poincare sphere.

[0106] like Figure 6 As shown in (1), right circularly polarized light (S3=+1) is incident on the liquid crystal cell 11C.

[0107] After twisting the liquid crystal unit 11C by 70°, the conversion is Figure 6 The polarization state of the plot of (2). Each plot point represents a different plot for wavelengths from 380nm to 780nm. Wavelengths around 550nm are linearly polarized light (on the equator such as on the Poincare sphere), and wavelengths other than this are plotted in the northern hemisphere of the Poincare sphere and become elliptically polarized light.

[0108] Then, through the first 1 / 4 wavelength film 12 (specifically, the 1 / 4 wavelength film of reverse wavelength dispersion), it becomes Figure 6 Drawing of (3).

[0109] Furthermore, if the second 1 / 4 wavelength film 13 (specifically, a 1 / 4 wavelength film with flat wavelength dispersion) is passed, as shown in FIG. Figure 6 As shown in the plot of (4), almost all wavelengths are emitted as left circularly polarized light (at the south pole position on the Poincare sphere). In other words, it can be seen that modulation is performed from right circularly polarized light to left circularly polarized light.

[0110] The second state (non-modulation) is also converted into linear polarized light once after passing through the liquid crystal unit 11C twisted by 70°. However, since the orientation of the liquid crystal unit 11C is rotated by 90° as a whole, it becomes linear polarized light with an angle of about 90° different from that of the first state (modulation). Then, after passing through the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13, all wavelengths become right circular polarized light. That is, the right circular polarized light can be emitted as right circular polarized light, which becomes non-modulation.

[0111] Thus, the first state and the second state refer to the same orientation of the dual-frequency driven liquid crystal molecules 310 such as a 70° twist, and the system as a whole is in a 90° phase difference relationship. If the liquid crystal element 10 of this embodiment is used, the first state and the second state can be reversibly switched, and a thin variable 1 / 2 wavelength plate (sHWP: Switchable Half Wave Plate) element with a wide band can be realized both when polarization is non-modulated and when polarization is modulated. In addition, which drive becomes the modulation state and the non-modulation state can be changed by the configuration of the phase difference film (the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13) and the substrate.

[0112] The retardation film 500 is, for example, a quarter wavelength film. The quarter wavelength film (specifically, the first quarter wavelength film 12 and the second quarter wavelength film 13) only needs to provide an in-plane retardation of 20 nm to 240 nm for light having a wavelength of at least 550 nm.

[0113] Examples of materials for the quarter-wavelength film include photopolymerizable liquid crystal materials, etc. Examples of the structure of the photopolymerizable liquid crystal material include a structure having a photopolymerizable group such as an acrylate group or a methacrylate group at the end of the liquid crystal molecule skeleton.

[0114] The 1 / 4 wavelength film can be formed by, for example, the following method. First, a photopolymerizable liquid crystal material is dissolved in an organic solvent such as propylene glycol monomethyl ether acetate (PGMEA). Next, the resulting solution is applied to the surface of a substrate (e.g., a polyethylene terephthalate (PET) film) to form a coating of the solution. The coating of the solution is then subjected to pre-firing, light irradiation (e.g., ultraviolet irradiation), and formal sintering in sequence to form a 1 / 4 wavelength film.

[0115] Alternatively, a liquid crystal polymer obtained by adding a chiral agent to the photopolymerizable liquid crystal material and polymerizing the material in a twisted state of 70° may be used as a quarter wavelength film.

[0116] As the quarter-wavelength film, for example, a stretched polymer film may be used. Examples of the material of the polymer film include cycloolefin polymer, polycarbonate, polysulfone, polyethersulfone, polyethylene terephthalate, polyethylene, polyvinyl alcohol, norbornene, triacetyl cellulose, diethyl cellulose, and the like.

[0117] The first 1 / 4 wavelength film 12 preferably has an inverse wavelength dispersion characteristic. By adopting this method, polarization modulation and polarization non-modulation can be switched in a wider band. Here, in this specification, "wavelength dispersion of phase difference film" refers to the correlation between the absolute value of the phase difference assigned by the phase difference film and the wavelength of the incident light. In the visible light region, the property that the absolute value of the phase difference assigned by the phase difference film does not change even if the wavelength of the incident light changes is called "flat wavelength dispersion characteristic". In addition, in the visible light region, the property that the absolute value of the phase difference assigned by the phase difference film decreases as the wavelength of the incident light increases is called "positive wavelength dispersion characteristic", and in the visible light region, the property that the absolute value of the phase difference assigned by the phase difference film increases as the wavelength of the incident light increases is called "inverse wavelength dispersion characteristic".

[0118] The in-plane phase difference of the first quarter wavelength film 12 at a wavelength of 450 nm is preferably 0.7 to 1 times the in-plane phase difference at a wavelength of 550 nm. By adopting this aspect, polarization modulation and polarization non-modulation can be switched over a wider frequency band.

[0119] The in-plane phase difference of the first quarter wavelength film 12 at a wavelength of 650 nm is preferably 1 to 1.3 times the in-plane phase difference at a wavelength of 550 nm. By adopting this aspect, polarization modulation and polarization non-modulation can be switched over a wider frequency band.

[0120] The in-plane phase difference of the first quarter wavelength film 12 at a wavelength of 550 nm is preferably 30 nm or more and 230 nm or less. By adopting such a mode, it is possible to switch between polarization modulation and polarization non-modulation in a wider frequency band.

[0121] When the azimuth angle of the alignment direction 311A ​​of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side in the first state is set to 0°, the azimuth angle of the lag axis of the 1 / 4 wavelength film farther from the light emitting side of the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13 (in this embodiment, the lag axis 12A of the first 1 / 4 wavelength film 12) is preferably 48° or more and 66° or less. By adopting such a method, polarization modulation and polarization non-modulation can be switched in a wider frequency band.

[0122] The second quarter wavelength film 13 preferably has a flat wavelength dispersion characteristic. By adopting such a method, it is possible to switch between polarization modulation and polarization non-modulation in a wider frequency band.

[0123] The in-plane phase difference of the second quarter wavelength film 13 at a wavelength of 550 nm is preferably 110 nm to 175 nm. By adopting such a mode, it is possible to switch between polarization modulation and polarization non-modulation in a wider frequency band.

[0124] When the azimuth angle of the alignment direction 311A ​​of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side in the first state is set to 0°, the azimuth angle of the lag axis of the 1 / 4 wavelength film on the side close to the light emitting side of the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13 (in this embodiment, the lag axis 13A of the second 1 / 4 wavelength film 13) is preferably 3° or more and 22° or less. By adopting this method, polarization modulation and polarization non-modulation can be switched in a wider band.

[0125] The angle between the slow axis 12A of the first quarter wavelength film 12 and the slow axis 13A of the second quarter wavelength film 13 is preferably 40° to 50°, more preferably 42° to 48°, further preferably 44° to 46°, particularly preferably 45°.

[0126] (Variation 1 of the First Embodiment) Figure 7 is a schematic cross-sectional view of a liquid crystal element of a modification example 1 of the first embodiment. The phase difference film 500 of the first embodiment is composed of two 1 / 4 wavelength films. On the other hand, the phase difference film 500 of this modification example is composed of one 1 / 4 wavelength film. Specifically, Figure 7 As shown, the phase difference film 500 of this modification is arranged on one side of the first substrate 100 opposite to the liquid crystal layer 300 and the second substrate 200 opposite to the liquid crystal layer 300, and the phase difference film 500 is a 1 / 4 wavelength film 14. By adopting this method, polarization modulation and polarization non-modulation can be switched in a wider band.

[0127] The 1 / 4 wavelength film 14 preferably has an inverse wavelength dispersion characteristic. By adopting such a mode, it is possible to switch between polarization modulation and polarization non-modulation in a wider band.

[0128] The in-plane phase difference of the quarter wavelength film 14 at a wavelength of 450 nm is preferably 0.7 to 1 times the in-plane phase difference at a wavelength of 550 nm. By adopting such a mode, polarization modulation and polarization non-modulation can be switched over a wider frequency band.

[0129] The in-plane phase difference of the quarter wavelength film 14 at a wavelength of 650 nm is preferably 1 or more and 1.3 or less relative to the in-plane phase difference at a wavelength of 550 nm. By adopting such a mode, polarization modulation and polarization non-modulation can be switched over a wider frequency band.

[0130] The in-plane phase difference of the quarter-wavelength film 14 at a wavelength of 550 nm is preferably 30 nm or more and 230 nm or less. By adopting such a mode, it is possible to switch between polarization modulation and polarization non-modulation in a wider frequency band.

[0131] When the azimuth angle of the alignment direction 311A ​​of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side in the first state is set to 0°, the azimuth angle of the slow axis of the 1 / 4 wavelength film 14 is preferably greater than 2° and less than 22°. By adopting this method, polarization modulation and polarization non-modulation can be switched in a wider band.

[0132] (Variation 2 of the first embodiment) Figure 8 Schematic diagram of a cross section of a liquid crystal element of a second variation of the first embodiment. The phase difference film 500 of the first embodiment is composed of two first quarter-wave films 12 and a second quarter-wave film 13. On the other hand, the phase difference film 500 of this variation is composed of a positive A plate and a negative A plate. Specifically, Figure 8 As shown, the phase difference film 500 of this embodiment is arranged on one side of the first substrate 100 opposite to the liquid crystal layer 300 and the second substrate 200 opposite to the liquid crystal layer 300, and the phase difference film 500 has a positive A plate 15 and a negative A plate 16 in order from the side close to the liquid crystal layer 300. By adopting such a method, polarization modulation and polarization non-modulation can be switched in a wider band. Hereinafter, a method in which the liquid crystal element 10 has a liquid crystal unit 11C, a positive A plate 15, and a negative A plate 16 in order from the incident side to the exit side is described.

[0133] The positive A-plate 15 is a layer satisfying nx>ny=nz. The in-plane phase difference of the positive A-plate 15 at a wavelength of 550 nm is preferably 30 nm to 230 nm. By adopting such a mode, polarization modulation and polarization non-modulation can be switched in a wider band.

[0134] When the azimuth angle of the alignment direction 311A ​​of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side in the first state is set to 0°, the azimuth angle of the slow axis of the film on the side away from the light emitting side of the positive A-plate 15 and the negative A-plate 16 (the positive A-plate 15 in this embodiment) is preferably 43° or more and 63° or less. By adopting such a method, polarization modulation and polarization non-modulation can be switched in a wider frequency band.

[0135] The negative A-plate 16 is a layer satisfying nz=nx>ny. The in-plane phase difference of the negative A-plate 16 at a wavelength of 550 nm is preferably 30 nm to 230 nm. By adopting such a mode, polarization modulation and polarization non-modulation can be switched in a wider band.

[0136] When the azimuth angle of the alignment direction 311A ​​of the dual-frequency driven liquid crystal molecules 311 on the first substrate 100 side in the first state is set to 0°, the azimuth angle of the slow axis of the film on the side close to the light emitting side of the positive A-plate 15 and the negative A-plate 16 (the negative A-plate 16 in this embodiment) is preferably greater than 0° and less than 20°. By adopting such a method, polarization modulation and polarization non-modulation can be switched in a wider frequency band.

[0137] (Variation 3 of the first embodiment) Fig. 9 It is a schematic perspective view of a liquid crystal element according to Modification 3 of the first embodiment. Fig.10 It is a schematic cross-sectional view of a liquid crystal element according to Modification 3 of the first embodiment. Fig.11 This is a schematic cross-sectional view of a variable focus element in which electrodes are provided only on the substrate on the incident side.

[0138] In the liquid crystal element 10 of the first embodiment, the first substrate 100 disposed on the incident side has the comb-tooth electrodes 11, and the second substrate 200 disposed on the emission side does not have the comb-tooth electrodes. Fig. 9 and Fig.10 As shown, in the liquid crystal element 10 of this modification, the first substrate 100 disposed on the incident side does not have the comb-tooth electrodes 11, and the second substrate 200 disposed on the emission side has the comb-tooth electrodes 11. By adopting such a system, the alignment stability can also be improved.

[0139] like Fig.10 As shown, the first substrate 100 or the second substrate 200 of the liquid crystal element 10 of this modification example includes a curved flexible printed circuit 10F, and the comb-tooth electrodes 11 are provided only on the first substrate 100 and the second substrate 200, which are located in the curved direction of the flexible printed circuit (FPC: Flexible Printed Circuit) 10F. Fig.10 as well as Fig.11 As shown, FPC10F is pressed onto the liquid crystal element 10 and driven by supplying voltage from an external circuit. For example, when applied to a head mounted display (HMD), FPC10F needs to be bent because it is contained in the housing of a headset. Usually, since the temple of the HMD has a circuit mechanism, it is bent toward the emission side. At this time, if there is an electrode on the incident side, as shown in FIG. Fig.11 As shown in FIG. 1 , the FPC 10F needs to be pressed against the substrate on the incident side, and the FPC 10F is easily peeled off due to the stress during bending. Fig.10 By providing an electrode substrate on the emission side in a manner bent toward the emission side as in this variation of the structure, the reliability of the device can be improved.

[0140] In this specification, "the bending direction of the FPC" means the direction in which the FPC is bent when the liquid crystal element is cross-sectionally viewed.

[0141] (Variation 4 of the first embodiment) Fig.12 1 is a perspective view of a liquid crystal element according to a fourth variation of the first embodiment. The liquid crystal element 10 of the first embodiment has a comb-tooth electrode 11 only on one side of the substrate. Fig.12 As shown, the comb-tooth electrode 11 includes a comb-tooth electrode 120 disposed on the first substrate side of the first substrate 100 and a comb-tooth electrode 220 disposed on the second substrate side of the second substrate 200, and the extension direction 120A of the comb-tooth electrode 120 on the first substrate side is parallel to the extension direction 220A of the comb-tooth electrode 220 on the second substrate side. By adopting such a method, the alignment stability can also be improved.

[0142] Fig.13 This is a graph showing the orientation direction of liquid crystal with respect to the thickness direction of the liquid crystal layer in the liquid crystal element according to the first embodiment. Fig.14 Graph showing the orientation of the liquid crystal relative to the thickness direction of the liquid crystal layer of the liquid crystal element of the fourth modification of the first embodiment. Fig.13 and Fig.14 As shown, in this variation in which the two substrates have comb-tooth electrodes, there may be a portion where the torsional change of the dual-frequency driven liquid crystal molecules 310 from the first substrate 100 to the second substrate 200 is weakened, compared with the above-mentioned first embodiment in which the substrate has comb-tooth electrodes only on one side. In the case of realizing the modulation state by voltage disconnection, since only the chiral agent added to the dual-frequency driven liquid crystal molecules is twisted and oriented, they are twisted from the first substrate 100 to the second substrate 200 with a uniform change amount. On the other hand, if the voltage between the first substrate 100 and the second substrate 200 is turned on, there is a region in the block where the torsional change becomes slow. At this time, the modulation characteristics of circularly polarized light can be improved. The orientation direction of the dual-frequency driven liquid crystal molecules in the middle of the block may be just torsionally relaxed, or there may be a region that is not twisted for a certain period of time.

[0143] (Second Embodiment) In this embodiment, the features unique to this embodiment are mainly described, and the description of the contents overlapped with those of the first embodiment and its modified example is omitted. This embodiment is substantially the same as the first embodiment and its modified example except that it further includes a Pancharatnamberi lens layer.

[0144] Fig.15 FIG. 4 is a schematic cross-sectional view of a variable focus element according to the second embodiment. Fig.15As shown in FIG. 1 , the variable focus element 30 of the present embodiment includes a liquid crystal element 10 and a Pancharatnamberry (PB) lens layer 20 disposed outside the liquid crystal element 10. As described above, the liquid crystal element 10 can modulate circularly polarized light. In addition, since the focal length of the PB lens layer 20 is different between right circularly polarized light and left circularly polarized light, a variable focus element 30 with a wide band and variable focus can be realized by combining the liquid crystal element 10 and the PB lens layer 20.

[0145] The PB lens layer 20 has the function of focusing and diverging circularly polarized light. The PB lens layer 20 can be produced, for example, by the method described in International Publication No. 2019 / 189818.

[0146] (Variation 1 of the Second Embodiment) Fig.16 2 is a schematic cross-sectional view of a variable focus element according to a first variation of the second embodiment. The PB lens layer 20 of the second embodiment is disposed on the outer side of the liquid crystal element 10 (ie, the outer unit). Fig.16 As shown, the variable focus element 30 of this modification includes a liquid crystal element 10 and a PB lens layer 21 disposed inside the liquid crystal element 10. According to such an embodiment, it is possible to realize a variable focus element 30 that can change the focus in a wide frequency band.

[0147] The in-cell PB lens layer 21 is an in-cell phase difference layer patterned in such a way that the slow axis direction rotates in the plane. The PB lens layer 21 can be in-celled by, for example, coating a photosensitive material for forming an in-cell PB lens containing a polymer on the second substrate 200 to form a film for forming a PB lens, and then performing an orientation treatment on the film for forming a PB lens, thereby making it possible to form the PB lens layer 21.

[0148] (Third Embodiment) In this embodiment, the features unique to this embodiment are mainly described, and the description of the contents overlapped with those of the first embodiment and its modification, and the second embodiment and its modification is omitted. In this embodiment, a head mounted display including the liquid crystal element 10 is described.

[0149] Fig.17 1 is a schematic diagram illustrating an example of a head mounted display according to the third embodiment. Fig.17 As shown, the head mounted display 1 of this embodiment includes a liquid crystal element 10. The head mounted display 1 is a display device that can be worn on the head of a user U, and is a binocular type immersive display that completely covers the user's eyes when worn on the head.

[0150] The head mounted display 1 includes: an image output unit 10Z having a function of displaying an image to a user U and having a liquid crystal element 10; an audio output unit 20Z having a function of generating audio such as sound, music, and sound effects; a wearing unit 30Z for integrally connecting the image output unit 10Z and the audio output unit 20Z and detachably wearing them on the head of the user U; and a face bumper 40Z disposed between the image output unit 10Z and the face of the user U. The image output unit 10Z of the present embodiment is composed of a single display.

[0151] The head mounted display 1 also includes a drive unit 50Z that outputs a video display signal and a sound output signal, and the drive unit 50Z is connected to the video output unit 10Z and the sound output unit 20Z by wire or wirelessly. Examples of wireless communication methods include Bluetooth (registered trademark).

[0152] Hereinafter, the effects of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0153] (Comparative Example 1) Fig.18 This is a schematic cross-sectional view of the liquid crystal element of Comparative Example 1. Fig.19 This is a schematic three-dimensional view of a liquid crystal element of Comparative Example 1. Fig. 20 Schematic diagram for explaining the alignment of liquid crystal molecules in the first state and the second state of the liquid crystal element of Comparative Example 1. Fig.21 This is a diagram showing the axis orientation of the liquid crystal element of Comparative Example 1.

[0154] Figure 18 to Figure 21 As shown, a liquid crystal element 10R of Comparative Example 1 corresponding to Example 1 of Patent Document 3 is produced. The liquid crystal element 10R of Comparative Example 1 includes, from the incident side to the outgoing side, a liquid crystal unit 11R having a liquid crystal layer 300R including a first substrate 100R, liquid crystal molecules 310R, and a second substrate 200R; a quarter-wave film with reverse wavelength dispersion as a first quarter-wave film 12R; and a quarter-wave film with flat wavelength dispersion as a second quarter-wave film 13R. The azimuth angle of the lag axis of the quarter-wave film with reverse wavelength dispersion (the lag axis 12AR of the first quarter-wave film 12R) is 57.2°, and the azimuth angle of the lag axis of the quarter-wave film with flat wavelength dispersion (the lag axis 13AR of the second quarter-wave film 13R) is 12.2°. The liquid crystal element 10R of Comparative Example 1 is specifically produced as follows.

[0155] A first substrate 100R including a first support substrate 110R and a first comb-tooth electrode 120R and a second substrate 200R including a second support substrate 210R and a second comb-tooth electrode 220R are prepared. The electrode direction of the first substrate 100R (the extension direction 120AR of the first comb-tooth electrode 120R) and the electrode direction of the second substrate 200R (the extension direction 220AR of the second comb-tooth electrode 220R) are formed when they are bonded together. Fig.21 The angle relationship is shown in FIG. 1. In addition, photo spacers with a height of 3.6 μm are arranged on the second substrate 200R.

[0156] Next, PMMA (polymethyl methacrylate) is manufactured for both the first substrate 100R including the first comb-tooth electrodes 120R and the second substrate 200R including the second comb-tooth electrodes 220R. Next, a sealing material is drawn on the second substrate 200R, and the first substrate 100R and the second substrate 200R are bonded together with a liquid crystal material (liquid crystal layer 300R) interposed therebetween, thereby manufacturing the liquid crystal cell 11R.

[0157] Here, as the liquid crystal material, a mixture of 5 wt% of dodecyl acrylate (C12A) and a chiral agent S-811 mixed with positive liquid crystal molecules (Δn=0.066) having positive dielectric anisotropy was used. The concentration of the chiral agent was set so that the twist angle between the upper and lower substrates in the liquid crystal cell was 70°.

[0158] After the liquid crystal cell 11R is heated to an isotropic phase state, the temperature is lowered to room temperature while a voltage is applied to the first substrate 100R, thereby obtaining a liquid crystal cell 11R having a uniform horizontal alignment and having a first weakly anchored horizontal alignment film 411R and a second weakly anchored horizontal alignment film 421R. Furthermore, a 1 / 4 wavelength film (first 1 / 4 wavelength film 12R) with reverse wavelength dispersion and a 1 / 4 wavelength film (second 1 / 4 wavelength film 13R) with flat wavelength dispersion are attached to the liquid crystal cell 11R obtained above, thereby obtaining a liquid crystal element (sHWP element) 10R of Comparative Example 1.

[0159] Fig. 22 Graph illustrating the voltage applied to the liquid crystal element of Comparative Example 1. Fig. 22 As shown, for the liquid crystal element 10R of Comparative Example 1, when a voltage is applied to the second substrate 200R, as shown in Fig. 20As shown, the liquid crystal molecules 312R on the second substrate 200R side are oriented in the 70° direction by the lateral electric field on the second substrate 200R side. Afterwards, if the voltage on the second substrate 200R is weakened (not zero), the liquid crystal molecules 312R on the second substrate 200R side are arranged in the 70° direction along the electric field direction, and the liquid crystal molecules 311R on the first substrate 100R side slide due to the chiral twisting force added to the liquid crystal material and are oriented in the 0° direction. This is the first state. In addition, even if the voltage is cut off afterwards, the orientation state of the first state is maintained.

[0160] In the opposite manner to the above, if a voltage is applied to the first substrate 100R and then weakened, Fig. 20 As shown, the liquid crystal molecules 311R on the first substrate 100R side are oriented in the 90° direction (azimuth angle 90°), and the liquid crystal molecules 312R on the second substrate 200R side are oriented in the 160° direction (azimuth angle 160°) by the chiral force. This is the second state. In this way, the liquid crystal element 10R of Comparative Example 1 can switch between the second state and the first state by applying a voltage to the first substrate 100R or applying a voltage to the second substrate 200R.

[0161] like Fig.21 As shown, the first state and the second state are the same in that the liquid crystal molecules 311R on the first substrate 100R side and the liquid crystal molecules 312R on the second substrate 200R side are twisted 70°, but the entire system is rotated 90°.

[0162] As described above, the liquid crystal element 10R of Comparative Example 1 includes positive liquid crystal molecules 310R, and the first substrate 100R and the second substrate 200R each include an electrode. The extension direction of the electrode is parallel or perpendicular to the orientation direction of the liquid crystal molecules located at the interface of the electrode. The average orientation direction of the liquid crystal of all liquid crystal molecules included in the liquid crystal layer is not parallel or perpendicular to the extension direction of the first comb-tooth electrode 120R, and is not parallel or perpendicular to the extension direction of the second comb-tooth electrode 220R. In the liquid crystal element 10R of Comparative Example 1, Fig. 22 In the driving method shown, the orientation of the liquid crystal molecules is maintained even when the voltage is turned off.

[0163] Fig.23 1 is a photograph showing the evaluation result of the orientation stability of the liquid crystal element of Comparative Example 1. After the liquid crystal element 10R of Comparative Example 1 was left at room temperature for 1 month, the liquid crystal element 10R was observed by a polarizing microscope. As a result, in the liquid crystal element 10R of Comparative Example 1, as shown in FIG. Fig.23 As shown, orientation defects were confirmed.

[0164] (Example 1) Fig.24This is a schematic diagram for explaining the alignment of liquid crystal molecules when the liquid crystal cell included in the liquid crystal element of Example 1 is heated to an isotropic phase state and then rapidly cooled. Fig.25 Schematic diagram for explaining the alignment of liquid crystal molecules in the first state and the second state of the liquid crystal element of Example 1. Fig.26 A diagram showing the axis orientation of the liquid crystal element of Example 1. Figure 1 to Figure 4 ,as well as Figure 24 to Figure 26 The liquid crystal element 10 shown in Example 1 corresponding to the first embodiment was produced as follows.

[0165] First, prepare a first substrate 100 and a second substrate 200. The first substrate 100 has a comb-tooth electrode 11 (120) arranged in a manner that the comb-tooth-shaped pixel electrode and the common electrode are interlocked with each other, and the second substrate 200 has a photospacer and no electrode. The electrode width of the comb-tooth electrode 120 is 3 μm, and the slit width (also called space) is 9 μm. The azimuth angle of the extension direction 11A (120A) of the comb-tooth electrode 11 (120) is set to 125°-305°.

[0166] Next, weakly anchored horizontal alignment films with infinitely small orientation limiting forces are manufactured for both the first substrate 100 and the second substrate 200. That is, a first weakly anchored horizontal alignment film 411 is formed on the first substrate 100, and a second weakly anchored horizontal alignment film 421 is formed on the second substrate 200. The first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 are not subjected to photo-alignment treatment or friction treatment, and the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 do not have uniaxial orientation. That is, the in-plane anisotropy of the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 is small. The in-plane phase difference of the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 is 0.8 nm. The azimuthal anchoring energy of the first weakly anchored horizontal alignment film 411 is 5×10 -6 J / m 2 The azimuthal anchoring energy of the second weakly anchored horizontally aligned film 421 is 5×10 -6 J / m 2 In this embodiment, a weak anchor film (returning to the initial alignment by voltage OFF) coated on a substrate is used as in a general alignment film. The first weak anchor horizontal alignment film 411 and the second weak anchor horizontal alignment film 421 are each composed of one polymer.

[0167] Next, a sealing material is drawn on the second substrate 200, and the first substrate 100 and the second substrate 200 are bonded together with a liquid crystal material (a liquid crystal layer 300 including dual-frequency driven liquid crystal molecules 310) sandwiched therebetween to produce a liquid crystal cell 11C. Here, as the liquid crystal material, a liquid crystal material in which a chiral agent is added to the dual-frequency driven liquid crystal molecules is used. The concentration of the chiral agent is adjusted so that the twist angle between the upper and lower substrates in the liquid crystal cell is 70°.

[0168] The liquid crystal element 10 of this embodiment has weakly anchored orientation films on both sides (the first weakly anchored horizontal orientation film 411 and the second weakly anchored horizontal orientation film 421), and thus orientation defects occur in the usual liquid crystal production process. Therefore, in this embodiment, after the liquid crystal unit 11C is heated to an isotropic phase state, a voltage is applied to the comb-tooth electrode 11 of the first substrate 100 while the temperature is lowered, thereby obtaining a liquid crystal element 10 without orientation defects. At this time, the voltage applied is less than the crossover frequency of the dual-frequency driven liquid crystal (specifically, 30Hz, 5V, and the sign of Δε of the liquid crystal molecules is positive). The result of this treatment is as follows. Fig.24 As shown, the average orientation direction of the liquid crystal molecules 310 driven by the dual frequency when the voltage is off is uniformly oriented in a state perpendicular to the extension direction 11A (120A) of the comb electrode 11 (120). In addition, as described above, the average orientation direction of the liquid crystal is measured using Axoscan.

[0169] A quarter wavelength film with reverse wavelength dispersion (first quarter wavelength film 12) and a quarter wavelength film with flat wavelength dispersion (second quarter wavelength film 13) are attached to the liquid crystal unit 11C obtained above, and the liquid crystal element (sHWP element) 10 of Example 1 is obtained. The first quarter wavelength film 12 and the second quarter wavelength film 13 in this embodiment are both positive A plates. The azimuth angle of the lag axis of the quarter wavelength film with reverse wavelength dispersion (lag axis 12A of the first quarter wavelength film 12) is 57.2°, and the azimuth angle of the lag axis of the quarter wavelength film with flat wavelength dispersion (lag axis 13A of the second quarter wavelength film 13) is 12.2.

[0170] The liquid crystal element 10 of this embodiment has the following relationship when no voltage is applied (also referred to as voltage off) or when driven at a frequency lower than the crossover frequency of high-frequency liquid crystal driving (also referred to as low-frequency driving): Fig.25 In this case, the incident circularly polarized light is emitted as opposite circularly polarized light (modulation state). On the other hand, when the dual-frequency liquid crystal is driven at a frequency higher than the crossover frequency (e.g., 300kHz) (also called high-frequency driving), the relationship between the components becomes Fig.25In this case, the incident circularly polarized light is emitted while maintaining the direction of the circularly polarized light (non-modulated state). Furthermore, if the state changes from high-frequency driving to voltage disconnection or low-frequency driving, the modulation state is restored. In this way, a device capable of switching circularly polarized light by changing the driving frequency of the liquid crystal molecules or applying / not applying voltage is obtained.

[0171] In this embodiment, the high voltage and the low voltage as in the above-mentioned comparative example 1 are not required, and the first state and the second state can be switched by switching on and off the voltage applied to the electrode provided only on one side of the substrate.

[0172] Fig. 27 is a photograph showing the evaluation result of the orientation stability of the liquid crystal element of Example 1. As in Comparative Example 1, the liquid crystal element 10 of Example 1 was left at room temperature for 1 month, and then observed by a polarizing microscope. As a result, in the liquid crystal element 10 of Example 1, as shown in FIG. Fig. 27 As shown, it was confirmed that a uniform orientation without any orientation defects was maintained.

[0173] The phase modulation element of Example 1 was evaluated for its optical state using Axoscan manufactured by Axometrics, and the circular polarization state of the light emitted when right circularly polarized light (light with S3 = +1) was incident was evaluated. In addition, the evaluation conditions were three visible wavelengths of 450nm / 550nm / 650nm and an incident azimuth of 0° to 40°. As a result, it was confirmed that the power value of the Stokes parameter S3 under all these conditions was -0.92 in the modulated state and 0.94 in the non-modulated state, and both states also had excellent modulation characteristics. In addition, in this evaluation, when light with S3 = +1 is incident on the liquid crystal element, if the emitted light is close to S3 = -1, it can be said to be an excellent modulated state, and if it is close to S3 = +1, it can be said to be an excellent non-modulated state. The case where the absolute value is 0.9 or above is considered qualified.

[0174] (Example 2) A liquid crystal element of Example 2 was produced in the same manner as Example 1 except that the electrode width of the comb-tooth electrode 11 was set to 3 μm and the slit width was set to 13 μm. That is, in Example 2, the space of the comb-tooth electrode 120 was wider than that in Example 1.

[0175] Similar to Example 1, the Stokes parameter S3 was also evaluated for Example 2. As a result, the liquid crystal element of Example 2 had S3=-0.95 in the modulated state and S3=0.96 in the non-modulated state, and had excellent polarization modulation characteristics. Similar to Example 1, it is believed that in Example 2, the liquid crystal molecules (bulks) away from the substrate interface react to the applied voltage. In this case, the wider the space, the more uniformly the liquid crystal molecules rotate in the plane, which can make the value of S3 better. Therefore, it is believed that the polarization modulation characteristics of Example 2 can be achieved compared with Example 1.

[0176] (Example 3) A liquid crystal element of Example 3 was produced in the same manner as Example 1 except that the electrode width of the comb-tooth electrode 11 was set to 2 μm and the slit width was set to 5 μm. That is, in Example 3, the comb-tooth electrodes 11 were set to have a narrower pitch than in Example 1.

[0177] Similar to Example 1, the Stokes parameter S3 was also evaluated for Example 3. As a result, the liquid crystal element of Example 3 had S3 = -0.91 in the modulated state and S3 = 0.92 in the non-modulated state, and had excellent polarization modulation characteristics. It can be seen that if the pitch is narrow, the voltage can be reduced, but the circular polarization modulation characteristics are slightly worse than those of Example 1.

[0178] (Example 4) Fig.28 This is a diagram showing the axis orientation of the liquid crystal element of Example 4. Figure 7 as well as Fig.28 The liquid crystal element 10 of Example 4, which corresponds to the modification 1 of the first embodiment, is shown. The liquid crystal element 10 of Example 4 does not include the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13, but has the same structure as that of Example 1 except that it includes a 1 / 4 wavelength film 14. The 1 / 4 wavelength film 14 is a 1 / 4 wavelength film of reverse wavelength dispersion, and the azimuth angle of the slow axis 14A is 12.2°.

[0179] Similar to Example 1, the Stokes parameter S3 was evaluated for Example 4. As a result, the liquid crystal element of Example 4 had an excellent polarization modulation characteristic, with S3 = -0.9 in the modulation state and S3 = 0.9 in the non-modulation state.

[0180] (Example 5) Fig.29 : is a diagram showing the axis orientation of the liquid crystal element of Example 5. Figure 8 as well as Fig.29The liquid crystal element 10 of Example 5, which corresponds to the second variation of the first embodiment, is shown. The liquid crystal element 10 of Example 5 does not include the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13, but has the same structure as that of Example 1 except that it includes the positive A plate 15 and the negative A plate 16.

[0181] The in-plane phase difference (Re) of the positive A plate 15 at a wavelength of 550nm is 140nm, the in-plane phase difference at a wavelength of 450nm is 1.01 relative to the in-plane phase difference at a wavelength of 550nm (Re(450) / Re(550)), the in-plane phase difference at a wavelength of 650nm is 0.99 relative to the in-plane phase difference at a wavelength of 550nm (Re(650) / Re(550)), and the azimuth angle of the lag axis 15A is 53°.

[0182] The in-plane phase difference (Re) of the negative A plate 16 at a wavelength of 550nm is 120nm, the in-plane phase difference at a wavelength of 450nm is 1.08 relative to the in-plane phase difference at a wavelength of 550nm (Re(450) / Re(550)), the in-plane phase difference at a wavelength of 650nm is 0.96 relative to the in-plane phase difference at a wavelength of 550nm (Re(650) / Re(550)), and the azimuth angle of the lag axis 16A is 10°.

[0183] Similar to Example 1, the Stokes parameter S3 was evaluated for Example 5. As a result, the liquid crystal element of Example 5 had excellent polarization modulation characteristics, with S3 = -0.94 in the modulation state and S3 = 0.95 in the non-modulation state.

[0184] According to Examples 4 and 5, it is known that the effect of the present invention can be achieved even with only one 1 / 4 wavelength film, but the polarization modulation characteristics are further improved by stacking a plurality of 1 / 4 wavelength films. In addition, it is known that the structure having both the positive A-plate 15 (axis azimuth of the slow axis 15A = 53°) and the negative A-plate 16 (axis azimuth of the slow axis 16A = 10°) is preferred in terms of wide viewing angle.

[0185] (Example 6) In addition to Fig. 9 In addition to the liquid crystal unit 11C of the modified example 3 of the first embodiment shown, a liquid crystal element 10 of Example 6 having the same structure as Example 1 was produced. The liquid crystal element 10 of this example has the same structure as Example 1 except that the first substrate 100 does not have the comb-tooth electrode 11 and the second substrate 200 has the comb-tooth electrode 11.

[0186] As with Example 1, the Stokes parameter S3 was evaluated for Example 6. As a result, the liquid crystal element 10 of Example 6 had excellent polarization modulation characteristics, with S3 = -0.92 in the modulation state and S3 = 0.94 in the non-modulation state.

[0187] like Fig.15 As shown, the PB lens layer 20 is attached to the liquid crystal element (phase modulation element) 10 of this embodiment, and a liquid crystal lens (variable focus element 30) having the PB lens layer 20 on the outside of the liquid crystal element 10 is manufactured. The variable focus element 30 of this embodiment has the comb-tooth electrode 11 only on the substrate (second substrate 200) located in the bending direction of the FPC 10F, and has the PB lens layer 20 on the outside of the liquid crystal element 10. It was confirmed that the liquid crystal lens (variable focus element 30) of this embodiment can change the focus in a wide frequency band.

[0188] Fig.30 It is a cross-sectional schematic diagram of the variable focus element of Example 6. Fig.31 It is a cross-sectional schematic diagram of a variable focus element having electrodes only on the substrate on the incident side. The liquid crystal element 10 of Examples 1 to 5 has a comb-tooth electrode 11 (IPS electrode) on the substrate (first substrate 100) located on the opposite side of the bending direction of the FPC 10F (i.e., the incident side), but the liquid crystal element 10 of this embodiment has a comb-tooth electrode 11 (IPS electrode) on the substrate (second substrate 200) located in the bending direction of the FPC 10F (i.e., the emission side), and it can be seen that this structure is also preferred.

[0189] (Example 7) Fig.16 A variable focus element 30 of Example 7 corresponding to the first variation of the second embodiment was produced. The variable focus element 30 of Example 7 has the same structure as the variable focus element 30 of Example 6, except that the first 1 / 4 wavelength film 12 and the second 1 / 4 wavelength film 13 are arranged on the side of the first substrate 100 opposite to the liquid crystal layer 300, and the PB lens layer 21 is arranged between the liquid crystal layer 300 and the second substrate 200.

[0190] In Example 7, a phase difference film (a first quarter wavelength film 12 and a second quarter wavelength film 13) is provided on the incident side, a PB lens layer 21 is provided between the second substrate 200 located on the emission side and the liquid crystal layer 300, and the second substrate 200 has electrodes. When the PB lens layer 21 is arranged on the inner side (In-cell) of the liquid crystal element 10, it is necessary to complete phase modulation before light passes through the PB lens layer 21, so the phase difference film (the first quarter wavelength film 12 and the second quarter wavelength film 13) is provided on the incident side. It was confirmed that the variable focus element 30 (liquid crystal lens) of this example has variable focus in a wide band.

[0191] Fig.32 2 is a cross-sectional view for explaining the wiring of the variable focus element of Example 7. As in Example 6, for the variable focus element of this embodiment, Fig.32 As shown, considering the strength against bending of the FPC, the stacked structure of this embodiment in which electrodes are arranged on the second substrate 200 located on the emission side (the bending direction of the FPC 10F) is considered to be suitable.

[0192] (Example 8) Fig.12 A liquid crystal element 10 of Example 8 having the same structure as that of Example 1 was produced except that the liquid crystal unit 11C of Modification 4 of the first embodiment was provided. The liquid crystal element 10 of this example has the same structure as that of Example 1 except that the first substrate 100 has the comb-tooth electrodes 120 on the first substrate side and the second substrate 200 has the comb-tooth electrodes 220 on the second substrate side. The extension directions (directions of the slits) of the comb-tooth electrodes 120 on the first substrate side and the comb-tooth electrodes 220 on the second substrate side are set to be parallel.

[0193] As with Example 1, the Stokes parameter S3 was evaluated for Example 8. As a result, the liquid crystal element of Example 8 had excellent polarization modulation characteristics, with S3 = -0.92 in the modulation state and S3 = 0.95 in the non-modulation state.

[0194] (Example 9) Fig.33 : is a diagram showing the axis orientation of the liquid crystal element of Example 9. Fig.33 The liquid crystal element 10 of Example 9 is shown. The liquid crystal element 10 of Example 9 has the same structure as the liquid crystal element 10 of Example 5, except that the azimuth angle of the lag axis 15A of the positive A plate 15 is 53°, the azimuth angle of the lag axis 16A of the negative A plate 16 is 10°, and the azimuth angle of the extension direction 120A of the comb-tooth electrode 120 is 45°.

[0195] In Examples 1 to 8, a modulation state can be achieved when the voltage is disconnected or when the frequency is low, and a non-modulation state can be achieved when the frequency is high. In the present embodiment, a non-modulation state can be achieved when the voltage is disconnected or when the frequency is low, and a modulation state can be achieved when the frequency is high.

[0196] As with Example 1, the Stokes parameter S3 was evaluated for Example 9. As a result, the liquid crystal element of Example 9 had S3 = -0.92 in the modulation state and S3 = 0.94 in the non-modulation state, and had excellent polarization modulation characteristics.

[0197] (Example 10) The liquid crystal element 10 of Example 10 was prepared in the same manner as in Example 1 except that the first weakly anchored horizontal alignment film 411 and the second weakly anchored horizontal alignment film 421 were formed using a material obtained by mixing two types of polymers having different refractive indices.

[0198] like Figure 5 As shown, in the liquid crystal element of Example 10, the polymer having a high refractive index is segregated on the substrate (first substrate 100 ) side, and the polymer having a low refractive index is segregated on the side in contact with the liquid crystal layer 300 .

[0199] The Stokes parameter S3 was evaluated for Example 10 in the same manner as in Example 1. As a result, the liquid crystal element of Example 10 had excellent polarization modulation characteristics, with S3 = -0.92 in the modulation state and S3 = 0.94 in the non-modulation state.

[0200] Furthermore, the haze of the liquid crystal elements of Example 1 and Example 10 was evaluated. As a result, the haze of the liquid crystal element of Example 1 was 4.3%, and the haze of the liquid crystal element of Example 10 was 2.1%, and the haze of the liquid crystal element of Example 10 was improved compared with that of Example 1.

[0201] Haze refers to a value determined by measuring diffuse transmittance and total light transmittance according to Haze (unit: %) = 100 × (diffuse transmittance) / (total light transmittance). The diffuse transmittance and total light transmittance were measured using a haze meter (product name: NDH-2000) manufactured by Nippon Denshoku Industries. Description of Reference Numerals

[0202] 1: Head-mounted display 10, 10R: Liquid crystal element 10F: Flexible Printed Circuit (FPC) 10Z: Image output unit 11, 120, 120R, 220, 220R: Comb electrode 11A, 120A, 120AR, 220A, 220AR: Extension direction 11C, 11R: Liquid crystal unit 11E: Linear electrode part 11S: Slit 12, 12R, 13, 13R, 14: 1 / 4 wavelength film 12A, 12AR, 13A, 13AR, 14A, 15A, 16A: Lag axis 15: Positive A plate 16: Negative A plate 20, 21: Panchalath Nampuri (PB) Lens Layer 20Z: Audio output unit 30Z: Installation 40Z: Face Buffer 50Z: Drivers 30: Variable focus element 100, 100R: First substrate 110, 110R, 210, 210R: Support substrate 200, 200R: Second substrate 300, 300R: Liquid crystal layer 310, 311, 312: Dual-frequency driving of liquid crystal molecules 310A: Average orientation direction of liquid crystal 310R, 311R, 312R: Liquid crystal molecules 311A, 311B, 312A, 312B: Orientation direction 411, 411R, 421, 421R: Weakly anchored horizontally oriented films 500: Retardation film E: Electric field U: User

Claims

1. A liquid crystal element, characterized in that: The liquid crystal element sequentially comprises a first substrate, a first weakly anchored horizontal alignment film, a liquid crystal layer containing dual-frequency driven liquid crystal molecules, a second weakly anchored horizontal alignment film and a second substrate. A comb-tooth electrode for generating an electric field to the liquid crystal layer is provided on at least one of the first substrate and the second substrate. The dual-frequency driven liquid crystal molecules are twisted and oriented between the first substrate and the second substrate in a voltage-applied state and a voltage-unapplied state, and the twisting direction in the voltage-applied state is the same as the twisting direction in the voltage-unapplied state. The alignment direction of the dual-frequency driven liquid crystal molecules located at the center of the liquid crystal layer in the thickness direction is orthogonal or parallel to the extension direction of the comb-tooth electrodes.

2. The liquid crystal element according to claim 1, characterized in that The azimuthal anchoring energy of the first weakly anchored horizontally aligned film is less than 1×10 -4 J / m 2 .

3. The liquid crystal element according to claim 1, characterized in that The first weakly anchored horizontal alignment film contains a polymer having at least one of a group represented by the following structural formula (P1) and a group represented by the following structural formula (P2), In the following structural formula, X has at least one of an ether group, an ester group and an amide group, R1, R2, R3 and R4 each independently represent a hydrocarbon group, and Y is a carbon atom or a silicon atom. [Chemical formula 1] [Chemical formula 2] 4. The liquid crystal element according to claim 1, characterized in that The azimuthal anchoring energy of the second weakly anchored horizontally aligned film is less than 1×10 -4 J / m 2 .

5. The liquid crystal element according to claim 1, wherein The second weakly anchored horizontal alignment film contains a polymer having at least one of a group represented by the following structural formula (P1) and a group represented by the following structural formula (P2), In the following structural formula, X has at least one of an ether group, an ester group and an amide group, R1, R2, R3 and R4 each independently represent a hydrocarbon group, and Y is a carbon atom or a silicon atom. [Chemical formula 3] [Chemical formula 4] 6. The liquid crystal element according to claim 1, characterized in that The first weakly anchored horizontal alignment film and the second weakly anchored horizontal alignment film do not have uniaxial alignment properties.

7. The liquid crystal element according to claim 1, characterized in that The in-plane phase difference between the first weakly anchored horizontal alignment film and the second weakly anchored horizontal alignment film is less than 1 nm.

8. The liquid crystal element according to claim 1, wherein In a state where no voltage is applied, the alignment direction of the dual-frequency driven liquid crystal molecules located at the center of the liquid crystal layer in the thickness direction is orthogonal to the extension direction of the comb-tooth electrodes.

9. The liquid crystal element according to claim 1, characterized in that The comb-tooth electrode is provided only on one of the first substrate and the second substrate.

10. The liquid crystal element according to claim 1, characterized in that The comb-tooth electrode has: A comb-tooth electrode on the first substrate side, which is disposed on the first substrate; as well as The comb-teeth electrode on the second substrate side is provided on the second substrate, An extending direction of the comb-teeth electrodes on the first substrate side is parallel to an extending direction of the comb-teeth electrodes on the second substrate side.

11. The liquid crystal element according to claim 1, wherein The ratio of the electrode width of the comb-tooth electrode to the slit width, that is, the electrode width: the slit width, is 1:2 to 1:

6.

12. The liquid crystal element according to claim 1, wherein The ratio of the thickness of the liquid crystal layer to the slit width of the comb-tooth electrode, that is, the thickness of the liquid crystal layer: the slit width is 1:2.5 to 1:

10.

13. The liquid crystal element according to claim 1, characterized in that A phase difference film is further provided on at least one of the first substrate on the side opposite to the liquid crystal layer and the second substrate on the side opposite to the liquid crystal layer.

14. The liquid crystal element according to claim 13, characterized in that The phase difference film includes a first quarter wavelength film and a second quarter wavelength film in order from the side close to the liquid crystal layer.

15. The liquid crystal element according to claim 1, characterized in that At least one of the first weakly anchored horizontal alignment film and the second weakly anchored horizontal alignment film contains at least two polymers, the at least two polymers are in contact with the comb-tooth electrode and have different refractive indices. The polymer with the smallest refractive index among the at least two polymers is in contact with the liquid crystal layer.

16. The liquid crystal element according to claim 1, characterized in that A ratio of the azimuthal anchoring energy of the second weakly anchored horizontal alignment film to the azimuthal anchoring energy of the first weakly anchored horizontal alignment film is 10 or less.

17. The liquid crystal element according to claim 1, characterized in that The first substrate or the second substrate comprises a curved flexible printed substrate, The comb-tooth electrodes are provided only on the substrate located in the bending direction of the flexible printed substrate among the first substrate and the second substrate.

18. A head mounted display, characterized in that: The liquid crystal element comprises the liquid crystal element according to any one of claims 1 to 17.

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