Lens device

Abstract

The invention provides a small lens device with variable focal length. The first and second liquid crystal layers have a circular center portion and a plurality of circular ring portions, the first and second liquid crystal layers are rotatable relative to each other, the inner diameter and the outer diameter of the nth circular ring portion from the center portion of the first and second liquid crystal layers are the same, and in polar coordinates of r and phi, r is greater than phi. When a pattern in which the optical axis direction [theta] 1 in a region where [phi] is [phi] 1 satisfies the relationship represented by formula 3 {[alpha] 1 * [phi] 1 + [theta] 0n1}-3 DEG < [theta] 1 < {[alpha] 1 * [phi] 1 + [theta] 0n1} + 3 DEG (where [theta] 0n1 is the optical axis direction at [phi] 1 = 0 DEG for each center portion and each circular ring portion) is a vortex orientation pattern, the center portion of the first liquid crystal layer has a vortex orientation pattern of [alpha] 1 = m * 0.5. The nth ring portion of the first liquid crystal layer has a vortex orientation pattern of [alpha] 1 = (m + n) * 0.5, the center portion of the second liquid crystal layer has a vortex orientation pattern of [alpha] 2 =-(m * 0.5), and the nth ring portion of the second liquid crystal layer has a vortex orientation pattern of [alpha] 2 =-(m + n) * 0.5.

Description

Technical Field

[0001] The invention relates to a lens device with variable focal length. Background Art

[0002] In head mounted displays (HMDs) such as AR (Augmented Reality) glasses, VR (Virtual Reality) glasses, and MR (Mixed Reality) glasses, there are lenses for forming images on the pupils of the user. Since the relative position of the HMD and the pupil changes depending on the user when the user wears the HMD, the lens is moved along the optical axis to change the focal length of the lens. In this case, the HMD becomes thicker in the optical axis direction and cannot be fully miniaturized.

[0003] On the other hand, Patent Document 1 describes an Alvarez lens in which the focal length of a lens is changed by relatively parallel movement of two liquid crystal films having lens functions in an in-plane direction.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 10877277 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] However, in the structure described in Patent Document 1 in which two liquid crystal films are moved in parallel in the in-plane direction, although the thickness of the lens in the optical axis direction can be reduced, the size of the area that acts as a lens is smaller than the liquid crystal film, and space is required for the two liquid crystal films to move in parallel, so the size in the in-plane direction becomes larger, making it impossible to fully miniaturize the lens.

[0009] The object of the present invention is to solve the problems of the prior art and provide a small lens device with variable focal length.

[0010] Means for solving technical problems

[0011] In order to solve the problem, the present invention has the following structure.

[0012] [1] A lens device comprising a first liquid crystal layer and a second liquid crystal layer,

[0013] The first liquid crystal layer and the second liquid crystal layer have a circular central portion and a plurality of annular portions having different inner diameters and being aligned with the center of the central portion and arranged in a radial direction of the central portion.

[0014] The center of the central portion of the first liquid crystal layer coincides with the center of the central portion of the second liquid crystal layer in the in-plane direction.

[0015] The first liquid crystal layer and the second liquid crystal layer can be relatively rotated around the center of the first liquid crystal layer without changing the distance between the first liquid crystal layer and the second liquid crystal layer.

[0016] The inner diameter r of the nth annular portion from the center of the first liquid crystal layer in-n1 And outer diameter r out-n1 and the inner diameter r of the nth annular portion from the center of the second liquid crystal layer in-n2 And outer diameter r out-n2 Satisfying the relationship expressed by equation 1 and equation 2,

[0017] Formula 1 0.9×r in-n1 ≤r in-n2 ≤1.1×r in-n1

[0018] Formula 2 0.9×r out-n1 ≤r out-n2 ≤1.1×r out-n1

[0019] In the polar coordinates of r and φ with the center of the center of the first liquid crystal layer as the origin, when the pattern in which the optical axis angle θ1 [°] of the first liquid crystal layer in the region where φ is φ1 satisfies the relationship represented by Formula 3 is defined as a vortex orientation pattern,

[0020] Formula 3 {α1×φ1+θ 0n1}-3°≤θ1≤{α1×φ1+θ 0n1}+3°

[0021] Among them, θ 0n1 [°] is the direction of the optical axis when φ1 = 0° for each center and each annular portion,

[0022] When m is an integer greater than or equal to 1, the center portion of the first liquid crystal layer has a vortex alignment pattern of α1=m×0.5.

[0023] The nth annular portion from the center of the first liquid crystal layer has a swirl alignment pattern of α1=(m+n)×0.5,

[0024] In the polar coordinates of r and φ with the center of the center of the second liquid crystal layer as the origin, when the pattern in which the optical axis angle θ2 [°] of the second liquid crystal layer in the region where φ is φ2 satisfies the relationship represented by Formula 4 is set as a vortex orientation pattern,

[0025] Formula 4 {α2×φ2+θ 0n2}-3°≤θ2≤{α2×φ2+θ 0n2}+3°

[0026] Among them, θ 0n2 [°] is the direction of the optical axis when φ2 = 0° for each center and each annular portion,

[0027] When m is an integer greater than or equal to 1, the center portion of the second liquid crystal layer has a vortex alignment pattern of α2=-(m×0.5).

[0028] The n-th annular portion from the center of the second liquid crystal layer has a swirl alignment pattern of α2=-(m+n)×0.5.

[0029] [2] The lens device according to [1], wherein:

[0030] When the azimuth in which the optical axis in the center of the first liquid crystal layer is parallel to the radial direction is taken as a reference, the azimuth angle in which the optical axis in the nth annular portion from the center is parallel to the radial direction is φ n1 ,

[0031] With the azimuth in which the optical axis in the center of the second liquid crystal layer is parallel to the radial direction as a reference, the azimuth in which the optical axis in the nth annular portion from the center is parallel to the radial direction is defined as φ n2 When:

[0032] φ n1 =φ n2 .

[0033] [3] The lens device according to [2], wherein:

[0034] When the azimuth angle of the optical axis in the center of the first liquid crystal layer parallel to the radial direction is φ 01 When φ n1 =φ 01 ,

[0035] When the azimuth angle of the optical axis in the center of the second liquid crystal layer parallel to the radial direction is φ 02 When φ n2 =φ 02 .

[0036] [4] The lens device according to any one of [1] to [3], which functions as an axicon lens.

[0037] [5] The lens device according to any one of [1] to [3], which functions as a spherical lens.

[0038] [6] The lens device according to any one of [1] to [3], which functions as an aspherical lens.

[0039] Effects of the Invention

[0040] According to the present invention, a compact lens device with a variable focal length can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a perspective view schematically showing an example of the lens device of the present invention.

[0042] Figure 2 This is a side view schematically showing an example of a liquid crystal layer included in the lens device of the present invention.

[0043] Figure 3 It is a plan view schematically showing an example of a first liquid crystal layer included in the lens device of the present invention.

[0044] Figure 4 yes Figure 3 A partially enlarged view of the first liquid crystal layer is shown.

[0045] Figure 5 This is a diagram for explaining the phase in the liquid crystal layer included in the lens device of the present invention.

[0046] Figure 6 This is a plan view schematically showing an enlarged portion of an example of a first liquid crystal layer included in the lens device of the present invention.

[0047] Figure 7 This is a conceptual diagram for explaining the swirl alignment pattern of the first liquid crystal layer.

[0048] Figure 8 This is a plan view schematically showing an enlarged portion of an example of a second liquid crystal layer included in the lens device of the present invention.

[0049] Fig. 9 This is a conceptual diagram for explaining the swirl alignment pattern of the second liquid crystal layer.

[0050] Fig.10 It is a diagram schematically showing the phase of a lens element.

[0051] Fig.11 It is a diagram schematically showing the phase of a lens element.

[0052] Fig.12 It is a diagram schematically showing the phase of a lens element.

[0053] Fig.13 It is a diagram schematically showing the phase of a lens element.

[0054] Fig.14 It is a diagram for explaining the operation of the lens device of the present invention.

[0055] Fig.15 It is a diagram schematically showing the phase of a lens element.

[0056] Fig.16 It is a diagram for explaining the operation of the lens device of the present invention.

[0057] Fig.17 This is a conceptual diagram of an example of an exposure device for exposing an alignment film for forming a liquid crystal layer.

[0058] Fig.18 This is a plan view schematically showing a vortex alignment pattern of the first liquid crystal layer produced in Example.

[0059] Fig.19 It is a top view schematically showing the swirl alignment pattern of the second liquid crystal layer produced in the example.

[0060] Fig. 20 This is a conceptual diagram of a measurement system for measuring focal length.

[0061] Fig.21 It is a diagram for explaining the influence of the error of the vortex orientation pattern.

[0062] Fig. 22 It is a diagram for explaining the influence of the error of the vortex orientation pattern. DETAILED DESCRIPTION

[0063] Hereinafter, the lens device of the present invention will be described in detail based on the preferred embodiments shown in the drawings.

[0064] In the present specification, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0065] In this specification, the terms "same", "identical" and the like include an error range generally allowed in the relevant technical field.

[0066] In this specification, "(meth)acrylate" is used to mean "either or both of acrylate and methacrylate".

[0067] In this specification, Re(λ) represents the in-plane retardation at a wavelength λ. Unless otherwise specified, the wavelength λ is set to 550 nm.

[0068] In this specification, Re(λ) is a value measured at a wavelength of λ by AxoScan (manufactured by Axometrics). The average refractive index ((nx+ny+nz) / 3) and the film thickness (d (μm)) are input into AxoScan to calculate

[0069] Slow axis direction (°)

[0070] Re(λ)=R0(λ).

[0071] In addition, R0(λ) is displayed as a numerical value calculated by AxoScan, but it means Re(λ).

[0072] [Lens devices]

[0073] The lens device of the present invention comprises a first liquid crystal layer and a second liquid crystal layer.

[0074] The first liquid crystal layer and the second liquid crystal layer have a circular central portion and a plurality of annular portions having different inner diameters and being aligned with the center of the central portion and arranged in a radial direction of the central portion.

[0075] The center of the central portion of the first liquid crystal layer coincides with the center of the central portion of the second liquid crystal layer in the in-plane direction.

[0076] The first liquid crystal layer and the second liquid crystal layer can be relatively rotated around the center of the first liquid crystal layer without changing the distance between the first liquid crystal layer and the second liquid crystal layer.

[0077] The inner diameter r of the nth annular portion from the center of the first liquid crystal layer in-n1 And outer diameter r out-n1 and the inner diameter r of the nth annular portion from the center of the second liquid crystal layer in-n2 And outer diameter r out-n2 Satisfying the relationship expressed by equation 1 and equation 2,

[0078] Formula 1 0.9×r in-n1 ≤r in-n2 ≤1.1×r in-n1

[0079] Formula 2 0.9×r out-n1 ≤r out-n2 ≤1.1×r out-n1

[0080] In the polar coordinates of r and φ with the center of the center of the first liquid crystal layer as the origin, when the pattern in which the optical axis direction θ1[°] of the first liquid crystal layer in the region where φ is φ1 satisfies the relationship represented by Formula 3 is defined as a vortex orientation pattern,

[0081] Formula 3 {α1×φ1+θ 0n1}-3°<θ1<{α1×φ1+θ 0n1}+3°

[0082] Among them, θ 0n1 [°] is the direction of the optical axis when φ1 = 0° for each center and each annular portion,

[0083] When m is an integer greater than or equal to 1, the center portion of the first liquid crystal layer has a vortex alignment pattern of α1=m×0.5.

[0084] The nth annular portion from the center of the first liquid crystal layer has a swirl alignment pattern of α1=(m+n)×0.5,

[0085] In the polar coordinates of r and φ with the center of the central part of the second liquid crystal layer as the origin, when the pattern in which the optical axis direction θ2[°] of the second liquid crystal layer in the region where φ is φ2 satisfies the relationship represented by Formula 4 is set as a vortex orientation pattern,

[0086] Formula 4 {α2×φ2+θ 0n2}-3°<θ2<{α2×φ2+θ 0n2}+3°

[0087] Among them, θ 0n2 [°] is the direction of the optical axis when φ2 = 0° for each center and each annular portion,

[0088] When m is an integer greater than or equal to 1, the center portion of the second liquid crystal layer has a vortex alignment pattern of α2=-(m×0.5).

[0089] The n-th annular portion from the center of the second liquid crystal layer has a swirl alignment pattern of α2=-(m+n)×0.5.

[0090] Figure 1 Detailed Description of the Invention A perspective view schematically showing an example of a lens device according to the present invention is shown in FIG.

[0091] Figure 1 The lens device 10 shown in the figure has a first liquid crystal layer 12 and a second liquid crystal layer 14 formed using a composition containing a liquid crystal compound. Figure 1 As shown, the first liquid crystal layer 12 and the second liquid crystal layer 14 are arranged in the thickness direction in a manner that the centers in the in-plane direction coincide with each other, and the first liquid crystal layer 12 and the second liquid crystal layer 14 are supported to be relatively rotatable without changing the distance in the thickness direction (stacking direction) with the center as the axis. In the lens device 10 of the present invention, either the first liquid crystal layer 12 or the second liquid crystal layer 14 can be rotated, or both can be rotated independently.

[0092] In the following description, when there is no need to distinguish between the first liquid crystal layer 12 and the second liquid crystal layer 14 , they are collectively referred to as liquid crystal layers.

[0093] The first liquid crystal layer 12 and the second liquid crystal layer 14 are formed using a composition containing a liquid crystal compound, and are oriented so that the optical axis derived from the liquid crystal compound becomes a spiral orientation pattern described later. In order to align the liquid crystal compound into a desired spiral orientation pattern, for example, Figure 2 As shown, the first liquid crystal layer 12 and the second liquid crystal layer 14 are formed on an alignment film 32 formed on a support 30 .

[0094] In addition, when used in the lens device 10, the first liquid crystal layer 12 and the second liquid crystal layer may be in a state of being stacked on the support 30 and the alignment film 32. Alternatively, for example, the support 30 may be peeled off, and only the alignment film 32 and the liquid crystal layer may be stacked. Alternatively, the support 30 and the alignment film 32 may be peeled off, and only the liquid crystal layer may be present.

[0095] Figure 3 It is a plan view schematically showing an example of the first liquid crystal layer 12 . Figure 3 The diagram shows the direction of the optical axis (slow axis) of each micro region of the first liquid crystal layer 12 using a phase normalized at 0 to 2π, and visualized using grayscales where 0 is black and 2π is white.

[0096] like Figure 3 As shown, the first liquid crystal layer 12 has a circular central portion and a plurality of annular portions having different inner diameters and being aligned with the center of the central portion and arranged in the radial direction of the central portion. Figure 3 In the example shown, the first liquid crystal layer 12 has a central portion and 19 annular portions. From the central portion toward the radial direction, the first annular portion is in contact with the central portion, and the second annular portion is in contact with the first annular portion. That is, each annular portion is formed so that its center is the same as the center of the central portion and is connected in sequence in a concentric circle shape.

[0097] like Figure 3 As shown in the middle grayscale, the phase (direction of the optical axis) of the center portion and each annular portion changes along the circumferential direction.

[0098] use Figure 4 The phase is described.

[0099] Figure 4 is a diagram showing the relationship between the orientation of the optical axis of each small area and the standardized phase. Figure 4 For the leftmost optical axis 40, the state in which the optical axis 40 is facing the left-right direction in the figure (the optical axis angle θ1 in the polar coordinate view described later is 0°) is defined as phase 0. Therefore, for the optical axis 40 shown on the rightmost side of the figure, the state in which the optical axis 40 is rotated 180° counterclockwise is defined as phase 2π, and the phase is standardized according to the angle of rotation in the counterclockwise direction. For example, the state in which the optical axis 40 is rotated 45° counterclockwise (the second optical axis 40 from the left) is phase π / 2, the state in which it is rotated 90° (the third optical axis 40 from the left) is phase π, and the state in which it is rotated 135° (the second optical axis 40 from the right) is phase 3π / 2. In addition, the change of the optical axis 40 is actually a continuous change. Figure 4 In the figure, there exists an optical axis (liquid crystal compound) 40 oriented at an angle between the optical axes 40. Also, as can be seen from the figure, the optical axis states of the phase 0 and the phase 2π are the same.

[0100] As an example, use Figure 5 The phase in the central portion 20 a of the first liquid crystal layer will be described. Figure 5 Yes means Figure 3 FIG. 1 is a diagram showing the phase of the center portion 20a of the first liquid crystal layer 12. Figure 5 In FIG. 1 , the phase in the first liquid crystal layer 12 (center portion 20a) is represented by grayscale, and the orientation of the optical axis 40 is superimposed. Basically, the orientation of the optical axis 40 in a micro region in the liquid crystal layer is the orientation of the optical axis derived from the liquid crystal compound. Therefore, Figure 5 The optical axis 40 in the image can also be said to be the optical axis of the liquid crystal compound. When the liquid crystal compound is a rod-shaped liquid crystal compound, the long axis of the rod-shaped liquid crystal compound is the optical axis derived from the liquid crystal compound. And, when the liquid crystal compound is a discotic liquid crystal compound, the axis perpendicular to the disc surface of the discotic liquid crystal compound is the optical axis.

[0101] like Figure 5 As shown, when the central portion 20a is observed in the counterclockwise direction along the circumference, the direction of the optical axis (liquid crystal compound) 40 in the micro region rotates in the counterclockwise direction. In the example shown in the figure, the optical axis 40 rotates half a circle during the period when the central portion 20a rotates one circle along the circumference of the central portion 20a from the position where the phase is 0, that is, the phase gradually changes from 0 to 2π.

[0102] Next, use Figure 6 The phase of the annular portion will be described.

[0103] Figure 6 It is a magnified representation Figure 3 The diagram of a portion of the first liquid crystal layer 12 shown is a diagram showing the phases of the central portion 20 a and the respective annular portions.

[0104] like Figure 6 As shown in the figure, when the first annular portion (first annular portion) 21a in the radial direction from the central portion 20a is observed in the counterclockwise direction along the circumferential direction of the first annular portion 21a, the direction of the optical axis 40 in the micro region rotates one circle in the counterclockwise direction. That is, in the example shown in the figure, the first annular portion 21a repeats the phase change from 0 to 2π twice during the period of rotating one circle along the circumferential direction of the first annular portion 21a from the position where the phase is 0. That is, the number of phase changes in the first annular portion 21a is one more than that in the central portion 20a.

[0105] Next, when the second annular portion (second annular portion) 22a in the radial direction from the center portion 20a is observed in the counterclockwise direction along the circumferential direction of the second annular portion 22a, the direction of the optical axis 40 in the micro region rotates 1.5 turns in the counterclockwise direction. That is, in the example shown in the figure, the second annular portion 22a repeats the phase change from 0 to 2π three times during the period of rotating one circle along the circumferential direction of the second annular portion 22a from the position where the phase is 0. That is, the number of phase changes in the second annular portion 22a is one more than that in the first annular portion 21a.

[0106] In the first liquid crystal layer 12, with respect to the third and subsequent annular portions extending radially from the center portion 20a, when observed counterclockwise along the circumference of the annular portion, the phase changes from 0 to 2π are repeated multiple times during the period in which the phase rotates from the position of 0 along the circumference of the annular portion for one circle, and the number of repetitions of the phase change is one more than that of the annular portion adjacent to the inner side.

[0107] That is, in Figure 3 In the first liquid crystal layer 12 shown, the n-th annular portion repeats the phase change n+1 times.

[0108] Thus, in the present invention, there is a central portion and a plurality of annular portions, and in each of the central portion and the plurality of annular portions, a phase change is performed more than once along the circumferential direction, and a pattern in which the phase change is repeated n+m times (m is the number of phase changes in the central portion) in the nth annular portion is called a vortex orientation pattern.

[0109] In this swirl orientation pattern, in the polar coordinates of r and φ with the center of the central portion 20a of the first liquid crystal layer 12 as the origin, the angle θ1 [°] of the optical axis 40 in the region where φ is φ1 is expressed by Formula 3a.

[0110] Formula 3a θ1=α1×φ1+θ 0n1

[0111] Among them, θ 0n1 [°] is the direction of the optical axis when φ1 = 0° for each center portion 20a and each annular portion. Figure 3 and Figure 6 In the example shown, in all the central portion 20a and the annular portion, θ 0n1 =0°.

[0112] When m is an integer greater than 1, the change in the angle θ1 of the optical axis 40 in the center portion 20a is represented by α1=m×0.5 in equation 3a. Also, the change in the angle θ1 of the optical axis in the nth annular portion from the center portion 20a is represented by α1=(m+n)×0.5 in equation 3a.

[0113] m has the same meaning as the number of phase changes in the central portion 20a. Figure 5 and Figure 6 In the example shown, m=1. Therefore, equation 3a in the center portion 20a becomes θ1=0.5×φ1+0° based on α1=1×0.5=0.5. According to this equation, the angle θ1 of the optical axis 40 in the center portion 20a is θ1=0° in the area where φ1=0°, θ1=45° in the area where φ1=90°, θ1=90° in the area where φ1=180°, θ1=135° in the area where φ1=270°, and θ1=180° in the area where φ1=360°. This is consistent with Figure 5 The examples shown are consistent.

[0114] and, Figure 6 Formula 3a in the first annular portion 21a of the example shown becomes θ1=1×φ1+0° according to α1=(1+1)×0.5=1. According to this formula, the angle θ1 of the optical axis 40 in the first annular portion 21a is θ1=0° in the area of ​​φ1=0°, θ1=90° in the area of ​​φ1=90°, θ1=180° in the area of ​​φ1=180°, θ1=270° in the area of ​​φ1=270°, and θ1=360° in the area of ​​φ1=360°. This is consistent with Figure 6 The first annular portion 21a of the illustrated example is consistent.

[0115] Likewise, Figure 6 Formula 3a in the second annular portion 22a of the example shown becomes θ1=1.5×φ1+0° according to α1=(1+2)×0.5=1.5. According to this formula, the angle θ1 of the optical axis 40 in the second annular portion 22a is θ1=0° in the area of ​​φ1=0°, θ1=135° in the area of ​​φ1=90°, θ1=270° in the area of ​​φ1=180°, θ1=405°=45° in the area of ​​φ1=270°, and θ1=540°=180° in the area of ​​φ1=360°. It can be seen that this is consistent with Figure 6 The second annular portion 22a of the example shown is consistent.

[0116] In the n-th annular portion, the angle θ1 of the optical axis 40 can also be calculated according to the formula 3a.

[0117] The first liquid crystal layer 12 of the lens device of the present invention satisfies the optical axis angle θ1 obtained by the above-mentioned formula 3a within the range of ±3°.

[0118] That is, in the polar coordinates of r and φ with the center of the central portion of the first liquid crystal layer as the origin, when the pattern in which the optical axis angle θ1 [°] of the first liquid crystal layer in the region where φ is φ1 satisfies the relationship expressed by the following Formula 3 is set as a vortex orientation pattern, the central portion of the first liquid crystal layer has a vortex orientation pattern of α1 = m×0.5 when m is set to an integer greater than 1, and the nth circular portion from the central portion of the first liquid crystal layer has a vortex orientation pattern of α1 = (m+n)×0.5.

[0119] Formula 3 {α1×φ1+θ 0n1}-3°<θ1<{α1×φ1+θ 0n1}+3°

[0120] (where θ 0n1 [°] is the optical axis direction when φ1 = 0° for each center and each annular portion)

[0121] On the other hand, the second liquid crystal layer 14, like the first liquid crystal layer 12, has a circular central portion and a plurality of annular portions which are consistent with the center of the central portion and have different inner diameters and are arranged in the radial direction of the central portion, and the circumferential phase change in the central portion and each annular portion has a vortex orientation pattern opposite to that of the first liquid crystal layer 12.

[0122] use Figure 7 The swirl alignment pattern of the second liquid crystal layer 14 will be described.

[0123] Figure 7 2 is a diagram showing a portion of the second liquid crystal layer 14 in an enlarged manner, and is a diagram showing the phases of the central portion 20b and each annular portion. Figure 7 In FIG. 1 , the phase in the second liquid crystal layer 14 is represented by grayscale, and the direction of the optical axis 40 is superimposed and shown.

[0124] like Figure 7 As shown, when the central portion 20b is observed in the counterclockwise direction along the circumference of the central portion 20b, the direction of the optical axis (liquid crystal compound) 40 in the micro region rotates in the clockwise direction. In the example shown in the figure, during the period when the central portion 20b rotates one circle along the circumference of the central portion 20b from the position where the phase is 2π(0), the optical axis 40 rotates half a circle in the opposite direction to the first liquid crystal layer 12, that is, the phase gradually changes from 2π to 0. In other words, in the central portion 20b, a phase change from 0 to 2π occurs in the clockwise direction along the circumference of the central portion 20b.

[0125] like Figure 7As shown, when the first annular portion (first annular portion) 21b in the radial direction from the center portion 20b is observed in the counterclockwise direction along the circumference of the first annular portion 21b, the direction of the optical axis 40 in the micro region rotates one circle in the clockwise direction. That is, in the example shown in the figure, the first annular portion 21b repeats the phase change from 2π to 0 twice during the period of rotating one circle along the circumference of the first annular portion 21b from the position with a phase of 2π. That is, the number of phase changes in the first annular portion 21b is one more than that in the center portion 20b. In addition, the phase change of the second liquid crystal layer 14 in the first annular portion 21b is opposite to the phase change of the first liquid crystal layer 12 in the first annular portion 21a. In other words, in the first annular portion 21b, the phase change from 0 to 2π is repeated twice in the clockwise direction along the circumference of the first annular portion 21b.

[0126] Next, when the second annular portion (second annular portion) 22b in the radial direction from the center portion 20b is observed in the counterclockwise direction along the circumference of the second annular portion 22b, the direction of the optical axis 40 in the micro region rotates 1.5 circles in the clockwise direction. That is, in the example shown in the figure, the second annular portion 22b repeats the phase change from 2π to 0 three times during one rotation along the circumference of the second annular portion 22b from the position with a phase of 2π. That is, the number of phase changes in the second annular portion 22b is one more than that in the first annular portion 21b. In addition, the phase change of the second liquid crystal layer 14 in the second annular portion 22b is opposite to the phase change of the first liquid crystal layer 12 in the second annular portion 22a. In other words, in the second annular portion 22b, the phase change from 0 to 2π is repeated three times in the clockwise direction along the circumference of the second annular portion 22b.

[0127] In the second liquid crystal layer 14, with respect to the third and subsequent annular portions extending radially from the center portion 20b, similarly, when observed counterclockwise along the circumference of the annular portion, the phase change from 2π to 0 is repeated multiple times during the period in which the phase rotates one circle from the position of 2π along the circumference of the annular portion, and the number of repetitions of the phase change is one more than that of the annular portion adjacent to the inner side.

[0128] That is, in Figure 7 In the second liquid crystal layer 14 shown, the n-th annular portion repeats the phase change n+1 times.

[0129] In this way, the second liquid crystal layer 14 has a central portion and multiple annular portions. In the central portion and each of the multiple annular portions, more than one phase change is performed in the direction opposite to the phase change in the first liquid crystal layer 12, and the nth annular portion repeats the phase change n+m times (m is the number of phase changes in the central portion).

[0130] Similar to the first liquid crystal layer 12, in this swirl orientation pattern, in the polar coordinates of r and φ with the center of the central portion 20b of the second liquid crystal layer 14 as the origin, the angle θ2 [°] of the optical axis 40 in the region where φ is φ2 is expressed by Formula 4a.

[0131] Formula 4a θ2=α2×φ2+θ 0n2

[0132] Among them, θ 0n2 [°] is the direction of the optical axis when φ2 = 0° for each center portion 20b and each annular portion. Figure 7 In the example shown, in all the central portion 20b and the annular portion, θ 0n2 =0°.

[0133] When m is an integer greater than 1, the change in the angle θ2 of the optical axis 40 in the center portion 20b is represented by α2=-(m×0.5) in Formula 4a. Also, the change in the angle θ2 of the optical axis in the nth annular portion from the center portion 20b is represented by α2=-(m+n)×0.5 in Formula 4a.

[0134] m has the same meaning as the number of phase changes in the central portion 20b. Figure 7 In the example shown, m=1. Therefore, equation 4a in the center portion 20b becomes θ2=-0.5×φ2+0° based on α2=-1×0.5=-0.5. According to this equation, the angle θ2 of the optical axis 40 in the center portion 20b is θ2=0° (=180°) in the area where φ2=0°, θ2=-45° (=135°) in the area where φ2=90°, θ2=-90° (=90°) in the area where φ2=180°, θ2=-135° (=45°) in the area where φ2=270°, and θ2=-180° (=0°) in the area where φ2=360°. It can be seen that this is consistent with Figure 5 The examples shown are consistent.

[0135] and, Figure 7 Formula 4a in the first annular portion 21b of the example shown becomes θ2 = 1 × φ2 + 0° according to α2 = -(1+1) × 0.5 = -1. According to this formula, the angle θ2 of the optical axis 40 in the first annular portion 21b is θ2 = 0° (= 180°) in the area where φ2 = 0°, θ2 = -90° (= 90°) in the area where φ2 = 90°, θ2 = -180° (= 0°) in the area where φ2 = 180°, θ2 = -270° (= 90°) in the area where φ2 = 270°, and θ2 = -360° (= 0°) in the area where φ2 = 360°. It can be seen that this is consistent with Figure 7 The first annular portion 21b of the illustrated example is consistent.

[0136] Likewise, Figure 7 Formula 4a in the second annular portion 22b of the example shown becomes θ2 = -1.5 × φ2 + 0° according to α2 = -(1+2) × 0.5 = -1.5. According to this formula, the angle θ2 of the optical axis 40 in the second annular portion 22b is θ2 = 0° (= 180°) in the area of ​​φ2 = 0°, θ2 = -135° (= 45°) in the area of ​​φ2 = 90°, θ2 = -270° (= 90°) in the area of ​​φ2 = 180°, θ2 = -405° (= -45° (= 135°) in the area of ​​φ2 = 270°, and θ2 = -540° (= -180°) in the area of ​​φ2 = 360°. It can be seen that this is consistent with Figure 7 The second annular portion 22b of the example shown is consistent.

[0137] In the n-th annular portion, the angle θ2 of the optical axis 40 can also be calculated according to the formula 4a.

[0138] The second liquid crystal layer 14 included in the lens device of the present invention satisfies the optical axis angle θ2 obtained by the above-mentioned formula 4a within the range of ±3°.

[0139] That is, in the polar coordinates of r and φ with the center of the central portion of the second liquid crystal layer as the origin, when the pattern in which the optical axis angle θ2 [°] of the second liquid crystal layer in the region where φ is φ2 satisfies the relationship expressed by the following Formula 4 is set as a vortex orientation pattern, the central portion of the second liquid crystal layer has a vortex orientation pattern of α2 = m × 0.5 when m is set to an integer greater than 1, and the nth circular portion from the central portion of the second liquid crystal layer has a vortex orientation pattern of α2 = (m + n) × 0.5.

[0140] Formula 4 {α2×φ2+θ 0n2}-3°<θ2<{α2×φ2+θ 0n2}+3°

[0141] (where θ 0n2 [°] is the direction of the optical axis when φ2 = 0° for each center and each annular portion)

[0142] In this swirl orientation pattern, the absolute values ​​of α1 and α2 match the number of rotations of the optical axis 40 when viewed counterclockwise along the circumferential direction. The positive and negative values ​​of α1 and α2 represent the rotation direction of the optical axis 40. α1 and α2 are defined as the number of the swirl orientation pattern.

[0143] An example showing the change of the optical axis when the order α is 0, 0.5, 1.0, and 1.5 is shown in more detail. Figure 8 , an example showing the change of the optical axis when the order α is -0.5, 1.0, and 1.5 is shown in more detail. Fig. 9 .

[0144] Here, the inner diameter r of the nth annular portion from the center of the first liquid crystal layer is in-n1 And outer diameter r out-n1 and the inner diameter r of the nth annular portion from the center of the second liquid crystal layer in-n2 And outer diameter r out-n2 The relationship expressed by equation 1 and equation 2 is satisfied.

[0145] Formula 1 0.9×r in-n1 ≤r in-n2 ≤1.1×r in-n1

[0146] Formula 2 0.9×r out-n1 ≤r out-n2 ≤1.1×r out-n1

[0147] That is, when the centers of the first liquid crystal layer 12 and the second liquid crystal layer 14 are aligned in the thickness direction, the centers and the n-th annular parts overlap each other when viewed from the thickness direction. Thus, the area of ​​the laminate of the first liquid crystal layer and the second liquid crystal layer that functions as a lens can be maintained.

[0148] The inner diameter r of the nth annular portion from the center of the first liquid crystal layer in-n1 And outer diameter r out-n1 The inner diameter r of the nth annular portion from the center of the second liquid crystal layer in-n2 And outer diameter r out-n2 It is preferable that the relationship represented by the following formula 1a and formula 2a is satisfied, and it is more preferable that the relationship represented by the following formula 1b and formula 2b is satisfied.

[0149] Formula 1a 0.95×r in-n1 ≤r in-n2 ≤1.05×r in-n1

[0150] Formula 2a 0.95×r out-n1 ≤r out-n2 ≤1.05×r out-n1

[0151] Formula 1b 0.975×r in-n1 ≤r in-n2 ≤1.025×r in-n1

[0152] Formula 2b 0.975×r out-n1 ≤r out-n2 ≤1.025×r out-n1

[0153] Furthermore, according to the above-mentioned Formula 3 and Formula 4, the number of times in the central portion 20a and the n-th annular portion of the first liquid crystal layer 12 is the same as the number of times in the central portion 20b and the n-th annular portion of the second liquid crystal layer 14. That is, the number of repetitions of the phase change in the central portion 20a and the n-th annular portion of the first liquid crystal layer 12 is the same as the number of repetitions of the phase change in the central portion 20b and the n-th annular portion of the second liquid crystal layer 14.

[0154] The lens device having the first liquid crystal layer 12 and the second liquid crystal layer 14 can change the focal length of the lens by relatively rotating the first liquid crystal layer 12 and the second liquid crystal layer 14 around the center as the axis without changing the distance between the first liquid crystal layer 12 and the second liquid crystal layer 14.

[0155] Use with Figure 3 and Figure 6 The first liquid crystal layer 12 and Figure 7 This point will be described using an example of a lens device of the second liquid crystal layer 14 shown.

[0156] The angle at which θ1 of the center portion 20a of the first liquid crystal layer 12 becomes 0° (i.e., phase 0) is set as the reference line of the first liquid crystal layer 12, the angle at which θ2 of the center portion 20b of the second liquid crystal layer 14 becomes 0° (i.e., phase 0=2π) is set as the reference line of the second liquid crystal layer 14, and the angle formed by the reference line of the first liquid crystal layer 12 and the reference line of the second liquid crystal layer 14 is set as the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14. In addition, regarding the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14, when the first liquid crystal layer 12 and the second liquid crystal layer 14 arranged in an overlapping manner are observed from the second liquid crystal layer 14 side, when the rotation direction of the reference line of the second liquid crystal layer 14 relative to the reference line of the first liquid crystal layer 12 is counterclockwise, it is set as positive, and when it is clockwise, it is set as negative, and it is expressed as -180° to 180°.

[0157] When the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 0°, the phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 becomes as follows: Fig.10 The state is schematically represented in .

[0158] When the phase is in such a state, that is, when the entire surface is in phase 0, the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 transmits light without diffracting it.

[0159] When the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 180°, the phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 becomes as follows: Fig.11 The state is schematically represented in .

[0160] When the phase is in such a state, that is, even when the phase distribution is only 0, π, or 2π, the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 transmits light without diffracting it.

[0161] Next, as an example, when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 30°, the phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 becomes as follows: Fig.12 The state is schematically represented in .

[0162] In this phase state, the phase in each region corresponding to the center and each annular portion is the same, and the phase in the region is different from the phase in the adjacent region. That is, it is a state in which there are regions with different phases in a concentric circle shape. When observing this phase state along the radial direction of each direction from the center, the phase changes continuously from the center to the outside. That is, Fig.12 The example shown can be said to have a pattern in which the optical axis changes while continuously rotating from the center toward the outside. If the direction in which the optical axis changes while continuously rotating is set as the arrangement axis, then Fig.12 The example shown can be said to have arrangement axes radially extending from the center toward the outside.

[0163] When the pattern has an optical axis that changes while continuously rotating, the circularly polarized light incident on the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14 is diffracted along the azimuth direction of the arrangement axis. The diffraction direction at this time is opposite in right-handed circularly polarized light and left-handed circularly polarized light. Fig.12 As shown, in the case of a phase state with an arrangement axis radially from the center toward the outside, as Fig.14 In the example shown, the lens acts as a focusing lens (convex lens) for focusing incident circularly polarized light. Fig.16 In the example shown, the lens functions as a diverging lens (concave lens) for diverging the other circularly polarized light.

[0164] Furthermore, for example, when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 60°, the phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 becomes as follows: Fig.13 The state is schematically represented in .

[0165] and Fig.12 Similarly, in the phase state, in each of the regions corresponding to the center and each annular portion, the phase within the region is the same, and the phases of the adjacent regions are different from each other. That is, there are regions with different phases in a concentric circle shape. And, Fig.13 The example shown can be said to be a pattern in which the arrangement axis in which the optical axis changes while continuously rotating from the center toward the outside has a radial shape.

[0166] And, if Fig.13As shown in FIG. 1 , when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to 60°, the period of phase change along the arrangement axis, that is, one period of 180° rotation of the optical axis, is shorter than when the relative angle is 30°. The shorter the one period, the larger the diffraction angle of light. Therefore, the focal length of the focusing lens that focuses light is shorter when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 30° than when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 60°. When the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 90°, the focal length is the shortest.

[0167] In this way, by changing the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14, the focal length of the stacked body functioning as a lens can be changed. Fig.14 As shown, for circularly polarized light that functions as a focusing lens by the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14, the focal length of the focusing can be changed by changing the relative angle. For circularly polarized light that functions as a diverging lens by the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14, the focal length of the divergence can be changed by changing the relative angle. At this time, the larger the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is between 0° and 90°, the shorter the focal length can be. Moreover, between the relative angle of 90° and 180°, the larger the relative angle is, the longer the focal length can be.

[0168] On the other hand, when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is -60°, the phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 becomes as follows: Fig.15 The state is schematically represented in .

[0169] and Fig.12 Similarly, in the phase state, in each of the regions corresponding to the center and each annular portion, the phase within the region is the same, and the phases of the adjacent regions are different from each other. That is, there are regions with different phases in a concentric circle shape. And, Fig.15 The example shown can be said to be a pattern in which the arrangement axis in which the optical axis changes while continuously rotating from the center toward the outside has a radial shape.

[0170] And, if Fig.15 As shown in FIG. 1 , when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to -60°, the direction of the phase change along the arrangement axis, that is, the rotation direction of the optical axis along the arrangement axis, is opposite to the case of a relative angle of 60°. If the rotation direction of the optical axis along the arrangement axis is opposite, the diffraction direction along the azimuth direction of the arrangement axis relative to the incident circularly polarized light is opposite. Therefore, it is opposite to the case where the relative angle between the circularly polarized light acting as a condensing lens and the circularly polarized light acting as a diverging lens is 60°.

[0171] At this time, also with Fig.13 and Fig.14 Similarly, the shorter the period of 180° rotation of the optical axis is, the larger the diffraction angle of the light is. Regarding the focal length, compared with the case where the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is -30°, it is shorter in the case of -60° and is the shortest in the case of -90°.

[0172] In this way, when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is changed in the negative direction, the focal length of the stacked body functioning as a lens can also be changed. Fig.16 As shown, regarding the circularly polarized light (i.e., the circularly polarized light that is focused when the relative angle is set to positive) in which the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14 acts as a diverging lens, the focal length of the divergence can be changed by changing the relative angle. Furthermore, regarding the circularly polarized light in which the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14 acts as a focusing lens, the focal length of the focusing can be changed by changing the relative angle. At this time, the larger the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is between 0° and -90°, the shorter the focal length can be. Furthermore, between the relative angle of -90° and -180° (=180°), the larger the relative angle is, the longer the focal length can be.

[0173] As described above, as a thin and variable focal length lens device, an Alvarez lens has been proposed that changes the focal length of the lens by relatively parallel movement of a liquid crystal film having a lens function in the in-plane direction. However, in a structure in which two liquid crystal films are parallel moved in the in-plane direction, although the thickness of the lens in the optical axis direction can be reduced, the size of the region that functions as a lens is smaller than the liquid crystal film, and a space is required for parallel movement of the two liquid crystal films, so the size in the in-plane direction becomes larger, resulting in a problem that the device cannot be fully miniaturized.

[0174] In contrast, as described above, the lens device of the present invention can change the focal length by relatively rotating the two liquid crystal layers without changing the distance in the thickness direction of the two liquid crystal layers, so that the size of the area that substantially functions as a lens can be made substantially the same as the size of the two liquid crystal layers. Therefore, a lens device that is thin, small in the in-plane direction, and has a variable focal length can be configured.

[0175] Here, the mechanism for relatively rotating the first liquid crystal layer 12 and the second liquid crystal layer 14 is not particularly limited, and various known rotation mechanisms such as an electric motor, an ultrasonic motor, and a rack-and-pinion mechanism can be appropriately used.

[0176] Furthermore, in the lens device 10 of the present invention, if the distance between the first liquid crystal layer 12 and the second liquid crystal layer 14 is too long, part of the light passing through the center portion and each annular portion of the first liquid crystal layer 12 is likely to be incident on other regions rather than the center portion and each annular portion corresponding to the second liquid crystal layer 14. In this case, the lens device 10 may not be able to properly exert the above-mentioned lens effect. Therefore, within the range in which the first liquid crystal layer 12 and the second liquid crystal layer 14 can be relatively rotated, the shorter the distance between the first liquid crystal layer 12 and the second liquid crystal layer 14, the more preferably.

[0177] Specifically, the distance between the first liquid crystal layer 12 and the second liquid crystal layer 14 is preferably 10 mm or less, more preferably 1 mm or less, and further preferably 0.1 mm or less.

[0178] Furthermore, there are no particular restrictions on the diameter of the center portion of the first liquid crystal layer 12 and the second liquid crystal layer 14, as well as the inner diameter, outer diameter, and radial width of each annular portion, and they may be appropriately set based on the focal length range required for the lens device 10, the lens diameter, the size of the light source, and the size of the device used.

[0179] The diameter of the center portion and the radial width of each annular portion in the first liquid crystal layer 12 and the second liquid crystal layer 14 are preferably 100 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less.

[0180] Furthermore, the width of each annular portion in the first liquid crystal layer 12 and the second liquid crystal layer 14 in the radial direction preferably decreases from the center toward the outside. Thus, in the phase state in the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14 when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to an angle that produces a lens effect, a cycle in which the optical axis rotates 180° along the direction of the arrangement axis gradually becomes shorter from the center toward the outside. The shorter a cycle is, the greater the refraction angle of the light. Therefore, by gradually shortening a cycle from the center along the arrangement axis toward the outside, the focusing power or diverging power of the light based on the stack of the first liquid crystal layer 12 and the second liquid crystal layer 14 can be further improved, and the performance as a convex lens or a concave lens can be improved.

[0181] And, in Figure 3 , Figure 6 , Figure 7 In the examples described in, for example, in the center of the first liquid crystal layer 12 and the second liquid crystal layer 14, a phase change from 0 to 2π occurs once during one rotation in the circumferential direction of the center. That is, m used to determine α1 and α2 in the above-mentioned equations 3 and 4 is set to 1, but it is not limited to this. The number of circumferential phase changes in the center, that is, m, can be 2 or more. When m is 2 or more, the number of circumferential phase changes in the n-th annular portion of the first liquid crystal layer 12 and the second liquid crystal layer 14 becomes m+n times.

[0182] Furthermore, the number of times α of each annular portion is set to 0.5 from the center toward the outside, but it is not limited thereto, and may also be 1.0, 1.5, etc. Furthermore, the amount of change in the number of times of adjacent annular portions may not be constant. However, from the viewpoint of being able to improve the performance as a lens, the number of times α of each annular portion is preferably 0.5 from the center toward the outside.

[0183] Here, in the above example, the azimuth direction in which the optical axis in the central portion 20a of the first liquid crystal layer 12 is parallel to the radial direction is completely consistent with the azimuth direction in which the optical axis in each annular portion is parallel to the radial direction. Furthermore, the azimuth direction in which the optical axis in the central portion 20b of the second liquid crystal layer 14 is parallel to the radial direction is completely consistent with the azimuth direction in which the optical axis in each annular portion is parallel to the radial direction. In other words, when the azimuth angle in which the optical axis in the central portion 20a of the first liquid crystal layer 12 is parallel to the radial direction is used as a reference, the azimuth angle in which the optical axis in the nth annular portion from the central portion is parallel to the radial direction is set to φ. n1 , taking the azimuth angle of the optical axis in the central portion 20b of the second liquid crystal layer 14 parallel to the radial direction as a reference, the azimuth angle of the optical axis in the nth annular portion from the central portion parallel to the radial direction is set as φ n2 When φ n1 =0° and φ n2 =0°.

[0184] However, the present invention is not limited to this. The azimuth angle φ at which the optical axis in each annular portion of the first liquid crystal layer 12 is parallel to the radial direction is n1 Furthermore, the azimuth angle φ of the optical axis in each annular portion of the second liquid crystal layer 14 parallel to the radial direction is n2 That is, for example, in the first liquid crystal layer 12, the φ n1 =φ 11 , φ in the second annular part n1 =φ 21 and φ in the third annular part n1 =φ 31 ...can be different. In addition, in the second liquid crystal layer 14, the φ n2 =φ 12 , φ in the second annular part n2 =φ 22 and φ in the third annular part n2 =φ 32 …can be different.

[0185] Furthermore, when the first liquid crystal layer 12 and the second liquid crystal layer 14 are respectively arranged at an azimuth angle (φ) in which the optical axis is parallel to the radial direction in each annular portion, n1 ,φ n2) are different, it is preferred that the azimuth φ in which the optical axis of the n-th annular portion of the first liquid crystal layer 12 is parallel to the radial direction n1 The direction φ in which the optical axis of the n-th annular portion of the second liquid crystal layer 14 is parallel to the radial direction n2 Satisfy φ n1 =φ n2 That is, for example, it is preferable that the first annular portion of the first liquid crystal layer 12 has a diameter of φ 11 The first annular portion of the second liquid crystal layer 14 has a diameter of φ 12 Similarly, the φ 21 The second annular portion of the second liquid crystal layer 14 has a diameter of φ 22 Similarly, the φ 31 The φ 32 same.

[0186] The n-th annular portion of the first liquid crystal layer 12 is formed by n1 The n-th annular portion of the second liquid crystal layer 14 has a diameter of φ n2 Satisfy φ n1 =φ n2 In the structure, when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to 0°, the stacked body (lens device) of the first liquid crystal layer 12 and the second liquid crystal layer 14 can transmit light without diffracting it. That is, by changing the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14, it is possible to switch between a state in which the stacked body (lens device) of the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to a condensing lens or a diverging lens and a state in which light is transmitted without diffracting it.

[0187] The lens device 10 including the first liquid crystal layer 12 and the second liquid crystal layer can function as an axicon lens, a spherical lens, or an aspherical lens.

[0188] Which type of lens the lens device 10 functions as is determined by the width of each annular portion of the first liquid crystal layer 12 and the second liquid crystal layer 14 .

[0189] For example, when the lens element is made to function as an axicon lens, the width of each annular portion of the first liquid crystal layer 12 and the second liquid crystal layer 14 may be set constant.

[0190] Furthermore, when the lens element is made to function as a spherical lens, the width of each annular portion of the first liquid crystal layer 12 and the second liquid crystal layer 14 may be appropriately determined to be inversely proportional to the 1 / 2 power of the width of the initial annular portion.

[0191] <Method for forming a liquid crystal layer having a vortex alignment pattern>

[0192] A liquid crystal layer having a vortex orientation pattern can be formed by applying a liquid crystal composition containing a liquid crystal compound onto an orientation film for orienting the liquid crystal compound into a predetermined vortex orientation pattern, thereby forming a liquid crystal phase in which the direction of the optical axis originating from the liquid crystal compound is oriented into the vortex orientation pattern and fixing it in a layered form.

[0193] Furthermore, in the present invention, the liquid crystal layer can also be formed by multi-layer coating. Multi-layer coating refers to a method in which the first layer of liquid crystal composition is coated on the alignment film, heated, cooled, and then ultraviolet curing is performed to form a liquid crystal fixing layer, and then the second layer and subsequent layers are overlapped and coated on the liquid crystal fixing layer, and similarly heated, cooled, and then ultraviolet curing is performed, and this operation is repeated until the desired thickness is reached to form a liquid crystal layer.

[0194] (Support)

[0195] As a support for supporting the alignment film and the optically anisotropic layer, various sheet-like objects (films, plates) can be used as long as they can support the alignment film and the optically anisotropic layer.

[0196] The transmittance of the support with respect to diffracted light is preferably 50% or more, more preferably 70% or more, and even more preferably 85% or more.

[0197] The thickness of the support is not limited, and may be appropriately set to a thickness capable of supporting the alignment film and the liquid crystal layer, depending on the application of the lens device and the material forming the support.

[0198] The thickness of the support is preferably 1 to 1000 μm, more preferably 3 to 250 μm, and even more preferably 5 to 150 μm.

[0199] The support may be a single layer or a multi-layer.

[0200] As a single-layer support, there can be exemplified a support made of glass, triacetyl cellulose (TAC), polyethylene terephthalate (PET), polycarbonate, polyvinyl chloride, acrylic acid, polyolefin, etc. As an example of a multi-layer support, there can be exemplified a support including any of the above-mentioned single-layer supports as a substrate, and a support having other layers disposed on the surface of the substrate.

[0201] (Oriented Film)

[0202] An alignment film is formed on the surface of the support.

[0203] The alignment film is an alignment film for aligning a liquid crystal compound in a predetermined spiral alignment pattern when forming a liquid crystal layer.

[0204] The alignment film is preferably a so-called photo-alignment film formed by irradiating a photo-alignment material with polarized light or non-polarized light. That is, in the present invention, the alignment film is preferably a photo-alignment film formed by coating a photo-alignment material on a support.

[0205] Irradiation with polarized light can be performed from a vertical direction or an oblique direction with respect to the photo-alignment film, and irradiation with unpolarized light can be performed from an oblique direction with respect to the photo-alignment film.

[0206] Examples of the photo-alignment material that can be used in the alignment film of the present invention include Japanese Patent Application Publication No. 2006-285197, Japanese Patent Application Publication No. 2007-76839, Japanese Patent Application Publication No. 2007-138138, Japanese Patent Application Publication No. 2007-94071, Japanese Patent Application Publication No. 2007-121721, Japanese Patent Application Publication No. 2007-140465, Japanese Patent Application Publication No. 2007-15643 Azo compounds described in Japanese Patent Publication No. 9, Japanese Patent Publication No. 2007-133184, Japanese Patent Publication No. 2009-109831, Japanese Patent No. 3883848 and Japanese Patent No. 4151746, aromatic ester compounds described in Japanese Patent Publication No. 2002-229039, and aromatic ester compounds described in Japanese Patent Publication No. 2002-265541 and Japanese Patent Publication No. 2002-317013. Maleimide and / or alkenyl-substituted nadic imide compounds having photo-alignment units, photo-crosslinkable silane derivatives described in Japanese Patent Nos. 4205195 and 4205198, photo-crosslinkable polyimides, photo-crosslinkable polyamides and photo-crosslinkable polyesters described in Japanese Patent Publication No. 2003-520878, Japanese Patent Publication No. 2004-529220 and Japanese Patent No. 4162850 Preferred examples include compounds capable of photodimerization described in JP-A-9-118717, JP-A-10-506420, JP-A-2003-505561, International Publication No. 2010 / 150748, JP-A-2013-177561, and JP-A-2014-12823, in particular cinnamate compounds, chalcone compounds, and coumarin compounds.

[0207] Among them, it is preferable to use an azo compound, a photo-crosslinkable polyimide, a photo-crosslinkable polyamide, a photo-crosslinkable polyester, a cinnamate compound, and a chalcone compound.

[0208] The thickness of the alignment film 32 is not limited, and may be appropriately set according to the material forming the alignment film 32 so as to obtain a desired alignment function.

[0209] The thickness of the alignment film 32 is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

[0210] In the present invention, a preferred exposure method for forming the alignment film of the vortex alignment pattern is a method of exposing the alignment film by a direct writing method.

[0211] exist Fig.17 2 is a diagram schematically showing an example of an exposure device for exposing an alignment film.

[0212] Fig.17 The exposure device 100 shown has a light source 102, a λ / 2 plate 104 for changing the polarization direction of light emitted from the light source 102, a lens 106 arranged on the optical path, and an XY stage 108. The exposure device 100 focuses a linearly polarized light beam directly on the alignment film to scan the focus position and draw an alignment pattern on the alignment film.

[0213] The light source 102 has a laser and a linear polarizer, and emits linear polarized light. The emitted linear polarized light is incident on the λ / 2 plate 104. The λ / 2 plate 104 is rotatably mounted and can rotate around an axis perpendicular to the XY plane of the XY stage 108. The λ / 2 plate 104 rotates around an axis perpendicular to the XY plane, and converts the polarization direction of the incident linear polarized light into an arbitrary direction. The lens 106 focuses the linear polarized light that has passed through the λ / 2 plate 104 on the surface of the orientation film 32 arranged on the XY stage 108. A support 30 having an orientation film 32 is arranged on the XY stage 108, and the position where the light on the surface of the orientation film 32 is focused is changed by moving the orientation film 32 (support 30) in the X direction and / or the Y direction. That is, the XY stage 108 scans the light on the surface of the orientation film 32.

[0214] The rotation of the λ / 2 plate 104 and the movement of the XY stage 108 are controlled by, for example, a computer, and a desired vortex orientation pattern is formed on the orientation film by making the position where light on the surface of the orientation film 32 is focused correspond to the polarization direction of the light.

[0215] The irradiation of the light beam from the light source 102, the rotation of the λ / 2 plate 104, and the XY stage 108 may be performed alternately or simultaneously. That is, for example, after the XY stage 108 is driven to move the alignment film 32 to a predetermined position and stop, and the λ / 2 plate 104 is rotated so that the polarization direction of the linear polarized light passing through the λ / 2 plate 104 becomes a predetermined direction, the light beam is irradiated from the light source 102 to expose a predetermined position on the surface of the alignment film 32, and then the irradiation of the light is stopped. Next, the XY stage 108 is driven again to move the alignment film 32 to the next predetermined position (exposure position) and stop, and the λ / 2 plate 104 is rotated so that the polarization direction of the linear polarized light passing through the λ / 2 plate 104 becomes a predetermined direction, and then the light beam is irradiated from the light source 102 to expose a predetermined position on the surface of the alignment film 32, and then the irradiation of the light is stopped. In this manner, the alignment film 32 may be exposed intermittently by alternately repeating the movement of the XY stage 108 and the irradiation of the light beam from the light source 102 .

[0216] Alternatively, the surface of the alignment film 32 may be continuously exposed by irradiating a light beam from the light source 102 while driving the XY stage 108 to move the alignment film 32 in a predetermined direction and rotating the λ / 2 plate 104 .

[0217] Alternatively, for example, the light beam from the light source 102 may be irradiated onto an area corresponding to a certain central portion or an annular portion, while the XY stage 108 may be driven to move the irradiation position circumferentially of the area, and the λ / 2 plate may be rotated according to the number of circumferential phase changes (rotational speed of the optical axis) to expose the area, and the areas corresponding to the central portion or the annular portion may be exposed separately by repeating this exposure.

[0218] The intensity of the irradiated light, the exposure time, etc. may be appropriately set according to the material of the alignment film.

[0219] The exposure amount per unit area can be adjusted by the intensity of the irradiated light and the scanning speed. From the viewpoint of sufficient exposure to impart orientation to the alignment film 32, 100 mJ / m 2 More preferably, 150 mJ / m 2 In addition, from the viewpoint of preventing the decrease of orientation due to excessive irradiation, 5 J / m 2 Below, more preferably 3 J / m 2 the following.

[0220] Furthermore, the spot diameter of the light beam focused on the alignment film may be a size that can provide a desired alignment pattern on the alignment film.

[0221] Furthermore, in the present invention, in order to set the optical axis angles θ1 and θ2 in the micro region of the liquid crystal layer to satisfy the structure of the above-mentioned formula 3 and formula 4, that is, in order to set the optical axis angles to be within the range of ±3° of the optical axis angles obtained by formulas 3a and 4a representing the above-mentioned ideal vortex orientation patterns, it is necessary to improve the exposure accuracy of the orientation film based on the direct drawing method. Therefore, in the present invention, it is preferred that when the orientation film is exposed by the direct drawing method, a mark for alignment is given to the support 30 or the orientation film 32, and when the XY stage 108 is driven to align the exposure position of the orientation film 32 with the prescribed position, the mark is detected by a camera, and the coordinates of the XY stage 108 are corrected based on the position information of the mark for alignment. Thus, strict alignment can be performed, so that the orientation film can be given a vortex orientation pattern that can form a liquid crystal layer with a small deviation in the optical axis angle relative to the ideal vortex orientation pattern.

[0222] The change in polarization angle of linear polarization (rotation amount of λ / 2 plate 104) when scanning the center and each annular portion is preferably 45° or less. By carefully plotting, the speed of change of the optical axis can be kept constant regardless of the characteristics of the liquid crystal material.

[0223] The movement amount of the movable stage is preferably less than one fifth of the length of the central portion and each annular portion in the circumferential direction. By carefully drawing, the speed of change of the optical axis can be kept constant regardless of the characteristics of the liquid crystal material.

[0224] The required accuracy of the movement amount of the movable stage is preferably 1 / 5 or less, more preferably 1 / 10 or less, and particularly preferably 1 / 20 or less.

[0225] In the present invention, as described above, it is preferable to detect the mark with a camera and correct the coordinates of the XY stage 108 based on the position information of the mark to perform positioning.

[0226] In order to determine the position coordinates and rotation angle of the alignment film 32 fixed on the XY stage 108, it is preferable to use a plurality of cameras when performing alignment. By using a plurality of cameras, the position coordinates of two points on the alignment film 32 that are sufficiently separated can be determined while maintaining the imaging magnification required for fine alignment, so that alignment can be performed while maintaining sufficient accuracy of the position coordinates and rotation angle.

[0227] The mark may be a single mark or multiple marks, as long as the positions of two points sufficiently separated can be confirmed by multiple cameras. Here, the two points sufficiently separated are preferably 10 mm or more, more preferably 30 mm or more, further preferably 50 mm or more, and particularly preferably 80 mm or more.

[0228] Furthermore, it is also preferable to use a plurality of cameras to simultaneously check the positions of two or more points.

[0229] Furthermore, it is sufficient to have a mark in at least one region, and it is preferable to have a mark in three or more regions. By having marks in three or more regions, it is possible to perform alignment using two marks provided at positions sandwiching the exposure region in the X direction, and it is possible to perform alignment using two marks provided at positions sandwiching the exposure region in the Y direction, so that the coordinates of the XY stage can be more accurately aligned.

[0230] The shape of the mark can be any shape such as a cross, a dot, a straight line, a circle, a quadrilateral, etc. Furthermore, the mark may be an aggregate or a grid.

[0231] (Liquid crystal layer)

[0232] The liquid crystal layer is formed on the surface of the alignment film 32 .

[0233] As described above, the liquid crystal layer is a liquid crystal layer in which the liquid crystal phase is fixed after the liquid crystal compound is aligned, and is a liquid crystal layer having a spiral alignment pattern.

[0234] <<Method for forming liquid crystal layer>>

[0235] The liquid crystal layer can be formed by fixing a liquid crystal phase in which a liquid crystal compound is oriented in a spiral orientation pattern in a layered state.

[0236] The structure formed by fixing the liquid crystal phase can be any structure that maintains the orientation of the liquid crystal compound in the liquid crystal phase. Typically, the following structure is preferred: on the basis of setting the polymerizable liquid crystal compound to an orientation state along the liquid crystal orientation pattern, it is polymerized and cured by ultraviolet irradiation, heating, etc. to form a layer without fluidity, and at the same time, it is changed to a state in which the orientation morphology will not change due to external fields or external forces.

[0237] In the structure in which the liquid crystal phase is fixed, the liquid crystal compound 40 may not exhibit liquid crystallinity in the liquid crystal layer as long as the optical properties of the liquid crystal phase are maintained. For example, the polymerizable liquid crystal compound may lose its liquid crystallinity by increasing its molecular weight through a curing reaction.

[0238] As a material used for forming a liquid crystal layer having a fixed liquid crystal phase, a liquid crystal composition containing a liquid crystal compound is mentioned as an example. The liquid crystal compound is preferably a polymerizable liquid crystal compound.

[0239] Furthermore, the liquid crystal composition used for forming the liquid crystal layer may further contain a surfactant, a polymerization initiator, and the like.

[0240] --Polymerizable Liquid Crystalline Compounds--

[0241] The polymerizable liquid crystal compound may be a rod-like liquid crystal compound or a disc-like liquid crystal compound.

[0242] As examples of rod-shaped polymerizable liquid crystal compounds forming the liquid crystal layer, rod-shaped nematic liquid crystal compounds can be cited. As rod-shaped nematic liquid crystal compounds, preferably used are azomethines, azoxyls, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolans, and alkenylcyclohexylbenzonitrile. Not only low molecular weight liquid crystal compounds but also high molecular weight liquid crystal compounds can be used.

[0243] It is more preferable to fix the alignment of the rod-like liquid crystal compound by polymerization. As the polymerizable rod-like liquid crystal compound, there can be used Makromol. Chem., Vol. 190, p. 2255 (1989), Advanced Materials 5, page 107 (1993), U.S. Patent No. 4,683,327, U.S. Patent No. 5,622,648, U.S. Patent No. 5,770,107, International Publication No. 95 / 22586, International Publication No. 95 / 24455, International Publication No. 97 / 00600, International Publication No. 98 / 23580, International Publication No. 98 / 52905, Japanese Patent Application No. 1-272551, Japanese Patent Application No. 6-16616, Japanese Patent Application No. 7-110469, Japanese Patent Application No. 11-80081 and Japanese Patent Application No. 2001-64627. In addition, as the rod-like liquid crystal compound, for example, the compounds described in Japanese Patent Publication No. 11-513019 and Japanese Patent Publication No. 2007-279688 can also be preferably used. In addition, two or more polymerizable liquid crystal compounds can be used simultaneously. If two or more polymerizable liquid crystal compounds are used simultaneously, the orientation temperature can be reduced.

[0244] Examples of polymerizable groups include unsaturated polymerizable groups, epoxy groups, and aziridine groups, preferably unsaturated polymerizable groups, and more preferably ethylenically unsaturated polymerizable groups. The polymerizable groups can be introduced into the molecules of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, and more preferably 1 to 3.

[0245] Furthermore, as polymerizable liquid crystal compounds other than the above, cyclic organopolysiloxane compounds having a cholesteric phase as disclosed in Japanese Patent Laid-Open No. 57-165480 can be used. In addition, as the polymer liquid crystal compound, a polymer having a mesogen group showing liquid crystal introduced into the main chain, the side chain, or both the main chain and the side chain, a polymer cholesteric liquid crystal having a cholesteric group introduced into the side chain, a liquid crystal polymer as disclosed in Japanese Patent Laid-Open No. 9-133810, and a liquid crystal polymer as disclosed in Japanese Patent Laid-Open No. 11-293252 can be used.

[0246] --Disc-like Liquid Crystalline Compounds--

[0247] As the discotic liquid crystal compound, for example, the discotic liquid crystal compounds described in Japanese Patent Application Laid-Open No. 2007-108732 or Japanese Patent Application Laid-Open No. 2010-244038 can be preferably used.

[0248] When a discotic liquid crystal compound is used for the liquid crystal layer, the liquid crystal compound 40 rises in the thickness direction of the liquid crystal layer, and an optical axis 40A derived from the liquid crystal compound is defined as an axis perpendicular to the disc surface, a so-called fast axis.

[0249] The amount of the polymerizable liquid crystal compound added to the liquid crystal composition is preferably 75 to 99.9% by mass, more preferably 80 to 99% by mass, and even more preferably 85 to 90% by mass, relative to the solid content mass of the liquid crystal composition (mass after removing the solvent).

[0250] As the liquid crystal compound, in order to obtain high diffraction efficiency, a liquid crystal compound having a high refractive index anisotropy Δn can be preferably used.

[0251] --Surfactant--

[0252] The liquid crystal composition used when forming the liquid crystal layer may contain a surfactant.

[0253] The surfactant is preferably a compound that can function as an alignment control agent that helps the liquid crystal compound to be oriented stably or quickly. Examples of the surfactant include silicone surfactants and fluorine surfactants, and preferably fluorine surfactants are used.

[0254] Specific examples of surfactants include compounds described in paragraphs

[0082] to

[0090] of JP-A-2014-119605, compounds described in paragraphs

[0031] to

[0034] of JP-A-2012-203237, compounds exemplified in paragraphs

[0092] and

[0093] of JP-A-2005-99248, compounds exemplified in paragraphs

[0076] to

[0078] and

[0082] to

[0085] of JP-A-2002-129162, and fluoro(meth)acrylate polymers described in paragraphs

[0018] to

[0043] of JP-A-2007-272185, etc.

[0255] The surfactant may be used alone or in combination of two or more.

[0256] As the fluorine-based surfactant, compounds described in paragraphs

[0082] to

[0090] of JP-A-2014-119605 are preferred.

[0257] The amount of the surfactant added in the liquid crystal composition is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.02 to 2% by mass, relative to the total mass of the liquid crystal compound.

[0258] --Polymerization Initiator--

[0259] When the liquid crystal composition contains a polymerizable compound, it preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is carried out by ultraviolet irradiation, the polymerization initiator used is preferably a photopolymerization initiator that can initiate the polymerization reaction by ultraviolet irradiation.

[0260] Examples of photopolymerization initiators include α-carbonyl compounds (described in U.S. Pat. No. 2,367,661 and U.S. Pat. No. 2,367,670), acyloin ethers (described in U.S. Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (described in U.S. Pat. No. 2,722,512), polynuclear quinone compounds (described in U.S. Pat. No. 3,046,127 and U.S. Pat. No. 2,951,758), a combination of a triaryl imidazole dimer and p-aminophenyl ketone (described in U.S. Pat. No. 3,549,367), acridine and phenazine compounds (described in Japanese Patent Application Laid-Open No. 60-105667 and U.S. Pat. No. 4,239,850), and oxadiazole compounds (described in U.S. Pat. No. 4,212,970).

[0261] The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 12% by mass, relative to the content of the liquid crystal compound.

[0262] --Crosslinking agent--

[0263] The liquid crystal composition may contain a crosslinking agent to increase the film strength after curing and improve durability. As the crosslinking agent, a crosslinking agent that is cured by ultraviolet rays, heat, moisture, etc. can be preferably used.

[0264] As a crosslinking agent, there is no particular limitation, and it can be appropriately selected according to the purpose, for example, multifunctional acrylate compounds such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate can be cited; epoxy compounds such as (meth) acrylic acid glycidyl ester and ethylene glycol diglycidyl ether; 2,2-bishydroxymethylbutanol-tri[3-(1-aziridine) propionate] and 4,4-bis(ethyleneiminocarbonylamino) diphenylmethane and other aziridine compounds; isocyanate compounds such as hexamethylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having oxazoline groups on the side chain; and alkoxysilane compounds such as vinyltrimethoxysilane, N-(2-aminoethyl) 3-aminopropyltrimethoxysilane, etc. In addition, it is possible to use a known catalyst according to the reactivity of the crosslinking agent, in addition to being able to improve film strength and durability, it is also possible to improve productivity. These can be used alone or in combination of more than two.

[0265] The content of the crosslinking agent is preferably 3 to 20% by mass, more preferably 5 to 15% by mass relative to the solid content of the liquid crystal composition. As long as the content of the crosslinking agent is within the above range, the effect of increasing the crosslinking density is easily obtained, thereby further improving the stability of the liquid crystal phase.

[0266] --Other additives--

[0267] A polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, metal oxide fine particles, and the like may be further added to the liquid crystal composition as necessary within a range that does not deteriorate optical properties.

[0268] In forming the liquid crystal layer, a liquid crystal composition is preferably used as the liquid.

[0269] The liquid crystal composition may contain a solvent. The solvent is not limited and can be appropriately selected according to the purpose, but an organic solvent is preferable.

[0270] The organic solvent is not limited and can be appropriately selected according to the purpose. For example, ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters and ethers can be mentioned. These can be used alone or in combination of two or more. Among these, ketones are preferred when the burden on the environment is taken into consideration.

[0271] When forming the liquid crystal layer, it is preferred that the liquid crystal composition is applied on the surface where the liquid crystal layer is to be formed, the liquid crystal compound is aligned in a liquid crystal phase in a predetermined liquid crystal alignment pattern, and then the liquid crystal compound is cured to form the liquid crystal layer.

[0272] That is, when forming a liquid crystal layer on the alignment film 32 , it is preferred that a liquid crystal composition is applied on the alignment film 32 , the liquid crystal compound is aligned into a predetermined liquid crystal alignment pattern, and then the liquid crystal compound is cured to form a liquid crystal layer having a fixed liquid crystal phase.

[0273] The liquid crystal composition can be applied by any known method that can uniformly apply a liquid to a sheet-like object, such as a printing method such as inkjet printing and roll printing, and a method such as spin coating, bar coating, and spray coating.

[0274] The applied liquid crystal composition is dried and / or heated as required, and then cured to form a liquid crystal layer. In the drying and / or heating process, the liquid crystal compound in the liquid crystal composition is oriented to a predetermined liquid crystal orientation pattern. When heating is performed, the heating temperature is preferably 200° C. or less, and more preferably 130° C. or less.

[0275] The aligned liquid crystal compound is further polymerized as required. The polymerization may be any of thermal polymerization and photopolymerization by light irradiation, but photopolymerization is preferred. Ultraviolet rays are preferably used for light irradiation. The irradiation energy is preferably 20 mJ / cm 2 ~50J / cm 2 , more preferably 50 to 1500 mJ / cm 2 In order to promote the photopolymerization reaction, light irradiation may be performed under heating conditions or in a nitrogen atmosphere. The wavelength of the ultraviolet rays to be irradiated is preferably 250 to 430 nm.

[0276] The thickness of the liquid crystal layer is not limited and may be appropriately set according to the purpose of the liquid crystal layer, the material forming the liquid crystal layer, and the like.

[0277] In the liquid crystal layer, the value of the in-plane retardation (Re) in the tiny region is preferably half the wavelength, i.e., λ / 2. The in-plane retardation is calculated by the product of the refractive index difference Δn associated with the refractive index anisotropy in the region and the thickness of the liquid crystal layer. Among them, the refractive index difference associated with the refractive index anisotropy of the region in the liquid crystal layer is a refractive index difference defined by the difference between the refractive index in the direction of the slow axis in the plane of the region and the refractive index in the direction orthogonal to the direction of the slow axis. That is, the refractive index difference Δn associated with the refractive index anisotropy of the region is equal to the difference between the refractive index of the liquid crystal compound in the direction of the in-plane optical axis of the region and the refractive index of the liquid crystal compound in the direction perpendicular to the optical axis. That is, the refractive index difference Δn is equal to the refractive index difference of the liquid crystal compound.

[0278] In the liquid crystal layer, the in-plane retardation value of the plurality of regions is preferably half a wavelength, but preferably the in-plane retardation Re(550) of the plurality of regions of the liquid crystal layer with respect to incident light having a wavelength of 550 nm is = Δn 550 ×d is within the range specified by the following formula (3). 550 is the refractive index difference caused by the refractive index anisotropy of the region when the wavelength of the incident light is 550nm, and d is the thickness of the liquid crystal layer.

[0279] 200nm≤Δn 550 ×d≤350nm……(3)

[0280] That is, if the in-plane retardation Re(550) of the plurality of regions of the liquid crystal layer is equal to Δn 550 ×d satisfies equation (3), it is possible to convert a sufficient amount of circularly polarized light components of light incident on the liquid crystal layer into circularly polarized light traveling in a direction tilted in the positive or negative direction relative to the arrangement axis direction. In-plane retardation Re(550) = Δn 550 More preferably, ×d is 225 nm ≤ Δn 550 ×d≤340nm, more preferably 250nm≤Δn 550 ×d≤330nm.

[0281] The above formula (3) is the range of the incident light with a wavelength of 550 nm, and the in-plane retardation Re(λ) of the plurality of regions of the liquid crystal layer with respect to the incident light with a wavelength of λ nm = Δn λ ×d is preferably within the range defined by the following formula (3-2), and can be appropriately set.

[0282] 0.7×(λ / 2)nm≤Δn λ ×d≤1.3×(λ / 2)nm……(3-2)

[0283] Furthermore, the in-plane retardation values ​​of a plurality of regions in the liquid crystal layer can also be used outside the range of the above formula (3). 550×d<200nm or 350nm<Δn 550 ×d, it can be divided into light traveling in the same direction as the incident light and light traveling in a direction different from the incident light. 550 When ×d is close to 0 nm or 550 nm, the component of light traveling in the same direction as the traveling direction of the incident light increases, and the component of light traveling in a direction different from the traveling direction of the incident light decreases.

[0284] In addition, each in-plane retardation of the region of the liquid crystal layer with respect to incident light having a wavelength of 450 nm is Re(450)=Δn 450 ×d, each in-plane retardation of the region of the liquid crystal layer with respect to incident light having a wavelength of 550 nm Re(550) = Δn 550 ×d preferably satisfies the following formula (4). Here, Δn 450 It is the refractive index difference associated with the refractive index anisotropy of the region when the wavelength of the incident light is 450 nm.

[0285] (Δn 450 ×d) / (Δn 550 ×d)<1.0……(4)

[0286] Formula (4) indicates that the liquid crystal compound contained in the liquid crystal layer has reverse dispersion. That is, by satisfying Formula (4), the liquid crystal layer can respond to incident light of a wide wavelength band.

[0287] In addition, it is the liquid crystal layer that functions as the λ / 2 plate, but the present invention includes a mode in which a laminate integrally provided with a support and an alignment film functions as the λ / 2 plate.

[0288] Here, the liquid crystal layer preferably has a twisted orientation of the liquid crystal compound (optical axis) in the thickness direction. "Twisted orientation of the liquid crystal compound (optical axis) in the thickness direction" refers to a state in which the orientation of the optical axis arranged in the thickness direction from one main surface of the liquid crystal layer to the other main surface is relatively changed and twisted in one direction. Twisting properties include right twisting properties and left twisting properties, but they can be applied according to the direction of diffraction. In addition, the twisting of the optical axis in the entire thickness direction is less than 1 circle, that is, the twisting angle is less than 360°. The twisting angle of the liquid crystal compound in the thickness direction is preferably about 10° to 200°, more preferably about 20° to 180°. In addition, the twisting direction can be opposite in the middle of the thickness direction. At this time, the twisting angle is also less than 360°, and the twisting angle of the liquid crystal compound in the thickness direction is preferably about 10° to 200°, more preferably about 20° to 180°. In the case of cholesteric orientation, the twisting angle is 360° or more and has selective reflectivity of reflecting specific circularly polarized light in a specific wavelength region. The "twisted alignment" in this specification does not include a cholesteric alignment, and selective reflectivity does not occur in a liquid crystal layer having a twisted alignment.

[0289] The liquid crystal layer with twisted orientation in the thickness direction has a twisted structure in which liquid crystal compounds are stacked and rotated in the thickness direction, and the total rotation angle from the liquid crystal compounds existing on one main surface side of the liquid crystal layer to the liquid crystal compounds existing on the other main surface side is less than 360°.

[0290] In order to make the liquid crystal layer have a structure in which the liquid crystal compound is twisted and aligned in the thickness direction, a chiral agent may be contained in the liquid crystal composition for forming the liquid crystal layer.

[0291] --Chiral Reagents (Optically Active Compounds)--

[0292] Chiral agents have the function of inducing a helical structure of a liquid crystal phase. Since the twisting direction and helical twisting power (HTP) of the helix induced by the compound are different, the chiral agent can be selected according to the purpose.

[0293] There are no particular restrictions on the chiral agent, and known compounds (for example, those recorded in Handbook of Liquid Crystal Devices, Chapter 3, Item 4-3, TN (twisted nematic), STN (Super Twisted Nematic) Chiral Agents, page 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989), isosorbide and isomannide derivatives, etc. can be used.

[0294] Chiral agents usually contain asymmetric carbon atoms, but axial chiral compounds or planar chiral compounds without asymmetric carbon atoms can also be used as chiral agents. In the example of axial chiral compounds or planar chiral compounds, binaphthyl, helicene, p-xylene dimer and their derivatives are included. Chiral agents can also have polymerizable groups. In the case where both the chiral agent and the liquid crystal compound have polymerizable groups, a polymer having repeating units derived from the polymerizable liquid crystal compound and repeating units derived from the chiral agent can be formed by the polymerization reaction of the polymerizable chiral agent and the polymerizable liquid crystal compound. In this way, the polymerizable group possessed by the polymerizable chiral agent is preferably a group of the same type as the polymerizable group possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridine group, more preferably an unsaturated polymerizable group, and further preferably an olefinic unsaturated polymerizable group.

[0295] Furthermore, the chiral agent may also be a liquid crystal compound.

[0296] When the chiral agent has a photoisomerizable group, it is preferred because the desired twisted orientation corresponding to the emission wavelength can be formed by irradiating a photomask with activating light or the like after coating and orientation. The photoisomerizable group is preferably an isomerization site of a compound showing photochromic properties, an azo group, an oxyazolyl group, or a cinnamoyl group. As specific compounds, compounds described in JP-A-2002-80478, JP-A-2002-80851, JP-A-2002-179668, JP-A-2002-179669, JP-A-2002-179670, JP-A-2002-179681, JP-A-2002-179682, JP-A-2002-338575, JP-A-2002-338668, JP-A-2003-313189, and JP-A-2003-313292 can be used.

[0297] The content of the chiral agent in the liquid crystal composition is preferably 0.01 to 200 mol %, more preferably 1 to 30 mol %, relative to the molar amount of the liquid crystal compound.

[0298] The above liquid crystal layers all use rod-shaped liquid crystal compounds as liquid crystal compounds, but the present invention is not limited thereto, and disc-shaped liquid crystal compounds may also be used.

[0299] In addition, in the case of a discotic liquid crystal compound, the optical axis originating from the liquid crystal compound is defined as an axis perpendicular to the disc plane, a so-called fast axis.

[0300] Furthermore, in the lens device of the present invention, the liquid crystal layer may use a combination of a rod-like liquid crystal compound and a disc-like liquid crystal compound.

[0301] Furthermore, the planar shape of the lens element (liquid crystal layer) is not limited to a circular shape, and may be appropriately set to a rectangular shape, an elliptical shape, an irregular shape, etc. according to the structure of a device using the lens element.

[0302] [Image display device and head mounted display]

[0303] The lens device of the present invention can be combined with a display panel to constitute an image display device.

[0304] Such an image display device having the lens device of the present invention can be preferably used as an image display device for head-mounted displays such as AR (Augmented Reality) glasses, VR glasses, and MR (Mixed reality) glasses.

[0305] As mentioned above, the lens device of the present invention has been described in detail, but the present invention is not limited to the above-mentioned examples, and it is a matter of course that various improvements or changes can be made without departing from the gist of the present invention.

[0306] Example

[0307] The following examples are given to further specifically describe the characteristics of the present invention. The materials, reagents, usage amounts, amounts, ratios, processing contents and processing steps shown in the following examples, as long as they do not depart from the gist of the present invention, can be appropriately changed. Therefore, the scope of the present invention should not be interpreted restrictively by the specific examples shown below.

[0308] [Example 1]

[0309] <Production of the first liquid crystal layer>

[0310] (Support)

[0311] As a support, a flat glass substrate was prepared.

[0312] (Formation of Orientation Film)

[0313] The following coating liquid for forming an alignment film was applied onto the support by spin coating, and the support on which the coating film of the coating liquid for forming an alignment film was formed was dried on a hot plate at 60° C. for 60 seconds to form an alignment film.

[0314] Coating liquid for forming an alignment film

[0315]

[0316]

[0317] -Photo-Orientation Material A-

[0318] [Chemical formula 1]

[0319]

[0320] (Exposure of Alignment Film)

[0321] A laser light source with a wavelength of 355 nm, a linear polarizer, a λ / 2 plate, a lens, and an XY stage (LD-242-MSC manufactured by CHUO PRECISION INDUSTRIAL CO., LTD.) were prepared. Fig.17 The exposure device of the direct drawing method shown in FIG. 1 is used to expose the alignment film, thereby forming a liquid crystal compound that is aligned as shown in FIG. Fig.18 The vortex orientation pattern of the oriented film P-1 is shown.

[0322] Specifically, a support body with an alignment film formed thereon was placed on an XY stage, and the lens position was adjusted so that the focus position was on the surface of the alignment film. A light source emitting a laser beam with a wavelength (355 nm) was used as a light source. Next, the movement of the XY stage was synchronized with the rotation of the λ / 2 plate so that the alignment direction of the liquid crystal compound (optical axis) became Fig.18 The orientation direction of the vortex orientation pattern shown was exposed so that the direction of the linear polarization of the laser beam irradiated at each position became a predetermined direction, thereby forming an orientation film P-1.

[0323] (Formation of Liquid Crystal Layer)

[0324] As a liquid crystal composition for forming a liquid crystal layer, the following composition A-1 was prepared.

[0325] Composition A-1

[0326]

[0327] Liquid crystal compound L-1

[0328] [Chemical formula 2]

[0329]

[0330] Leveling agent T-1

[0331] [Chemical formula 3]

[0332]

[0333] The liquid crystal layer is formed by coating the composition A-1 on the alignment film P-1 in multiple layers. Multilayer coating means that the following treatment is repeated: first, the first layer of the composition A-1 is coated on the alignment film, and then the liquid crystal fixing layer is prepared by ultraviolet curing after heating, and then the second layer and later are coated on the liquid crystal fixing layer by overlapping the coating composition, and then heated and ultraviolet curing are performed in the same manner. Formed by multilayer coating, even when the total thickness of the optically anisotropic layer becomes thicker, the alignment direction of the alignment film is reflected from the lower surface to the upper surface of the liquid crystal layer.

[0334] First, in the first layer, the composition A-1 was applied on the oriented film P-1, and the coating was heated to 80° C. on a hot plate. Then, a high pressure mercury lamp was used in a nitrogen atmosphere at 300 mJ / cm 2 The coating film was irradiated with ultraviolet rays having a wavelength of 365 nm, thereby fixing the alignment of the liquid crystal compound.

[0335] After the second layer, the composition was coated on the liquid crystal fixing layer, and then heated and cured by ultraviolet light under the same conditions as above to produce a liquid crystal fixing layer. In this way, the coating was repeated until the total thickness reached the desired film thickness, thereby forming the first liquid crystal layer. The thickness of the first layer was set to 1.8 μm.

[0336] The first liquid crystal layer was confirmed to be as follows using a polarizing microscope. Fig.18 The case of the spiral alignment pattern shown in FIG.

[0337] <Production of the Second Liquid Crystal Layer>

[0338] like Fig.19 As shown in FIG. 1 , the second liquid crystal layer is produced in the same manner as the first liquid crystal layer, except that the second liquid crystal layer has a swirl alignment pattern different from that of the first liquid crystal layer.

[0339] <Production of lens devices>

[0340] The first liquid crystal layer and the second liquid crystal layer thus produced are stacked so as to be relatively rotatable to produce a lens device. The first liquid crystal layer is brought into contact with the second liquid crystal layer.

[0341] [evaluate]

[0342] <Evaluation of focal length>

[0343] For use Fig. 20 The evaluation system schematically shown in the figure was used to evaluate the variable focal length of the produced lens device.

[0344] Fig. 20The illustrated evaluation system 200 includes a light source 202 , a louver film 204 , a louver film 206 , a bandpass filter 208 , and a screen 210 , and a first liquid crystal layer 12 and a second liquid crystal layer 14 are disposed between the bandpass filter 208 and the screen 210 .

[0345] As the light source 200, a white LED light source was used. As the louver film 204 and the louver film 206, a security / privacy filter PF240W2E manufactured by 3M Company was used. In addition, the louver film 204 and the louver film 206 were arranged so that the louvers were orthogonal. As the bandpass filter 208, a bandpass filter (manufactured by Edmund Optics Inc., #65-155) that only allows green light to pass was used. As the screen 210, white paper was used.

[0346] White light is emitted from the light source 200 and is transmitted through two louver films, thereby becoming parallel light. Then, it is transmitted through the bandpass filter 208 and becomes green light. The green light sequentially transmits the first liquid crystal layer 12 and the second liquid crystal layer 14 and is irradiated onto the screen 210. The screen 210 is moved along the optical axis to a position where the spot diameter of the light on the screen 210 is the smallest, and the distance d between the second liquid crystal layer 14 and the screen 210 at this time is taken as the focal length, and the focal length is calculated.

[0347] When the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 30°, the focal length is 73 cm. When the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 60°, the focal length is 35 cm. When the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 90°, the focal length is 25 cm.

[0348] As described above, it can be confirmed that the focal length is changed by changing the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14. It is known that the lens device of the present invention has a thin thickness in the optical axis direction of the lens and can change the focal length without changing the size in the in-plane direction.

[0349] [Simulation test]

[0350] The influence of the deviation of the optical axis θ1 in the first liquid crystal layer 12 and the second liquid crystal layer 14 was confirmed by simulation.

[0351] In the first liquid crystal layer 12 and the second liquid crystal layer 14 fabricated in Example 1, the optical axis angle of the first liquid crystal layer 12 is set to θ1={α1×φ1+θ 0n1}±α, the optical axis angle of the second liquid crystal layer 14 is set to θ2={α2×φ2+θ 0n2}±α, α is changed to 0°, 0.5°, 1.0°, 2.5°, 5.0° and 7.5°, and a random number is generated between ±α, thereby simulating the situation where there is a deviation in the vortex orientation pattern (optical axis angle) of the first liquid crystal layer 12 and the second liquid crystal layer 14. In addition, in the first liquid crystal layer 12 and the second liquid crystal layer 14 produced in Example 1, θ 0n1 =0°,θ 0n2 =0°.

[0352] The phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to 60° was determined by simulation. The results are shown in Fig.21 middle. Fig.21 In the figure, the graphs represented by ±0 to ±7.5 are the results when α is 0° to 7.5°.

[0353] Similarly, the phase of the stacked body of the first liquid crystal layer 12 and the second liquid crystal layer 14 when the relative angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is set to 30° was determined by simulation. The results are shown in Fig. 22 .exist Fig. 22 In the figure, the graphs represented by ±0 to ±7.5 are the results when α is 0° to 7.5°.

[0354] Depend on Fig.21 and Fig. 22 It can be seen that when α is 0°, that is, from the ideal state, as α increases, the phase change becomes chaotic and the boundary becomes blurred. In addition, when α is less than 2.5°, the phase change in the radial direction is sufficiently generated, so it can accurately function as a lens. On the other hand, it can be seen that when α is more than 5°, the phase change in the radial direction is not sufficiently generated. In this case, it cannot accurately function as a lens.

[0355] It can be seen from the above results that the effect of the present invention is obvious.

[0356] Explanation of symbols

[0357] 10-lens device, 12-first liquid crystal layer, 14-second liquid crystal layer, 20a, 20b-central portion, 21a, 21b-first annular portion, 22a, 22b-second annular portion, 30-support body, 32-orientation film, 40-optical axis (liquid crystal compound), 100-exposure device, 102-light source, 104-λ / 2 plate, 106-lens, 108-XY stage, 200-evaluation system, 202-light source, 204, 206-louver film, 208-bandpass filter, 210-screen.

Claims

1. A lens device comprising a first liquid crystal layer and a second liquid crystal layer, The first liquid crystal layer and the second liquid crystal layer have a circular central portion and a plurality of annular portions having different inner diameters and being aligned with the center of the central portion and arranged in a radial direction of the central portion. The center of the central portion of the first liquid crystal layer coincides with the center of the central portion of the second liquid crystal layer in an in-plane direction. The first liquid crystal layer and the second liquid crystal layer can be relatively rotated around the center of the first liquid crystal layer without changing the distance between the first liquid crystal layer and the second liquid crystal layer. The inner diameter r of the nth annular portion of the first liquid crystal layer from the center portion is in-n1 And outer diameter r out-n1 and the inner diameter r of the nth annular portion of the second liquid crystal layer from the center portion in-n2 And outer diameter r out-n2 Satisfying the relationship expressed by equation 1 and equation 2, Formula 1 0.9×r in-n1 ≤r in-n2 ≤1.1×r in-n1 Formula 2 0.9×r out-n1 ≤r out-n2 ≤1.1×r out-n1 In the polar coordinates of r and φ with the center of the central portion of the first liquid crystal layer as the origin, when a pattern in which the optical axis angle θ1 [°] of the first liquid crystal layer in a region where φ is φ1 satisfies the relationship represented by Formula 3 is set as a vortex orientation pattern, Equation 3 {α1×φ1+θ 0n1}-3°≤θ1≤{α1×φ1+θ 0n1}+3° in, θ 0n1 [°] is the direction of the optical axis when φ1=0° for each of the central portion and each of the annular portions, When m is an integer greater than or equal to 1, the central portion of the first liquid crystal layer has a vortex alignment pattern of α1=m×0.5, The nth annular portion of the first liquid crystal layer from the central portion has a swirl alignment pattern of α1=(m+n)×0.5, In the polar coordinates of r and φ with the center of the central portion of the second liquid crystal layer as the origin, when a pattern in which the optical axis angle θ2 [°] of the second liquid crystal layer in a region where φ is φ2 satisfies the relationship represented by Formula 4 is set as a vortex orientation pattern, Equation 4 {α2 × φ2 + θ 0n2}-3° ≤ θ2 ≤ {α2 × φ2 + θ 0n2}+3° Among them, θ 0n2 [°] is the direction of the optical axis when φ2=0° for each of the central portion and each of the annular portions, When m is an integer greater than or equal to 1, the central portion of the second liquid crystal layer has a vortex alignment pattern of α2=-(m×0.5), The n-th annular portion of the second liquid crystal layer from the central portion has a swirl alignment pattern of α2=-(m+n)×0.

5.

2. The lens device according to claim 1, wherein: When the azimuth in which the optical axis in the center of the first liquid crystal layer is parallel to the radial direction is taken as a reference, the azimuth angle in which the optical axis in the nth annular portion from the center is parallel to the radial direction is φ n1 , With the orientation of the optical axis in the center of the second liquid crystal layer being parallel to the radial direction as a reference, the orientation angle of the optical axis in the nth annular portion from the center being parallel to the radial direction is set to φ n2 When: f n1 =φ n2 。 3. The lens device according to claim 2, wherein: When the azimuth angle of the optical axis in the center of the first liquid crystal layer parallel to the radial direction is φ 01 When φ n1 =φ 01 , When the azimuth angle of the optical axis in the center of the second liquid crystal layer parallel to the radial direction is φ 02 When φ n2 =φ 02 .

4. The lens device according to any one of claims 1 to 3, wherein: The lens element functions as an axicon lens.

5. The lens device according to any one of claims 1 to 3, wherein: The lens device functions as a spherical lens.

6. The lens device according to any one of claims 1 to 3, wherein: The lens device functions as an aspherical lens.

Images