Liquid crystal film and method for identifying center point of lens region of liquid crystal film

Abstract

Provided are: a liquid crystal film in which the optical center point of a lens region can be easily identified; and a method for identifying the center point of the lens region. The liquid crystal film has a liquid crystal layer formed using a composition containing a liquid crystal compound, wherein: the liquid crystal layer has a lens region that has a liquid crystal alignment pattern in a radial shape extending from the inside to the outside, the liquid crystal alignment pattern having an orientation of an optical axis derived from the liquid crystal compound changing while continuously rotating toward an in-plane direction; the liquid crystal layer also has two or more detectable detection points either inside or outside the lens region; and the center point of the lens region is defined by the distances from the two or more detection points.

Description

Liquid crystal film, and method for identifying the center point of the lens area of ​​the liquid crystal film.

[0001] The present invention relates to a liquid crystal film and a method for identifying the center point of the lens region of the liquid crystal film.

[0002] Optical elements that control the direction of light are used in various optical devices. For example, optical elements that control the direction of light are used in a variety of optical devices, such as the backlight of liquid crystal display devices, head-mounted displays (HMDs) such as AR (Augmented Reality) glasses, VR (Virtual Reality) glasses, and MR (Mixed Reality) glasses that overlay virtual images and various information onto the actual view, head-up displays (HUDs), projectors, beam steering, and sensors for detecting objects and measuring the distance to objects.

[0003] As an optical element for controlling the direction of light in this way, it has been proposed to use an optical sheet (optical element) having a liquid crystal layer formed by aligning liquid crystal compounds in a predetermined orientation using a liquid crystal composition containing liquid crystal compounds.

[0004] For example, Patent Document 1 describes a liquid crystal diffraction element having at least an optically anisotropic layer (liquid crystal layer) formed using a liquid crystal composition containing a liquid crystal compound, wherein the optically anisotropic layer has a liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating along at least one direction in the plane, and when the length of one period is defined as the length of a 180-degree rotation of the optical axis along one direction, one period gradually changes along one direction, and when the average period over 50 periods along one direction from the period with the longest period length is defined as Λa, when the main surface of the optically anisotropic layer is observed with an optical microscope, the ratio of the maximum and minimum widths of 30 consecutive bright fringes and the ratio of the maximum and minimum widths of 30 consecutive dark fringes within the region are both 1.2 or less.

[0005] Furthermore, Patent Document 1 describes how an optically anisotropic layer (liquid crystal layer) acts as a lens by having a radial pattern in one direction of the liquid crystal alignment pattern that extends from the inside outwards.

[0006] International Publication No. 2023 / 101002

[0007] Such optical sheets are typically cut to a size that includes a lens-producing region (lens region) for use. Furthermore, these optical sheets are often laminated onto other optical elements.

[0008] When cutting an optical sheet to a size that includes the lens area, or when laminating it onto other optical elements, high-precision alignment is necessary. For example, if the optical sheet has a lens effect, it is desirable to use the center point of the lens area as a reference point to cut the optical sheet to the desired size or to align and laminate it with other optical elements. However, a liquid crystal layer formed using a liquid crystal composition containing liquid crystal compounds appears as a flat film, and its lens effect is exerted by the action of the liquid crystal alignment pattern, so the center (for example, the apex of the convex in the case of a convex lens) cannot be visually observed like a typical lens. Therefore, in order to detect the center point of the lens area, it is necessary to combine it with a polarizing filter or the like and assemble an optical system specifically for that optical sheet, making it difficult to easily identify.

[0009] The object of the present invention is to solve the problems of the prior art and to provide a liquid crystal film having a liquid crystal layer having a lens region that exhibits a lens effect, in which the optical center point of the lens region can be easily identified, and a method for identifying the center point of the lens region.

[0010] The inventors have found that the above problem can be solved by the following configuration.

[0011] [1] A liquid crystal film having a liquid crystal layer formed using a composition containing a liquid crystal compound, wherein the liquid crystal layer has lens regions having a liquid crystal orientation pattern radially from the inside to the outside, in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane, and has two or more detectable detection points either inside or outside the lens regions, and the center point of the lens region is defined by the distance from the two or more detection points. [2] The liquid crystal film according to [1], wherein the detection points are outside the lens regions of the liquid crystal layer. [3] The liquid crystal film according to [1] or [2], wherein the liquid crystal layer has multiple lens regions. [4] The liquid crystal film according to [3], wherein there are multiple sets of combinations of two or more detection points corresponding to each of the multiple lens regions. [5] The liquid crystal film according to any one of [1] to [4], wherein there are two detection points, and the two detection points and the center point of the lens region lie on a straight line. [6] The liquid crystal film according to [5], wherein the center point of the lens region lies between the two detection points. [7] A liquid crystal film according to any one of [1] to [6], wherein a detection point is provided in the liquid crystal layer, and the orientation state of the liquid crystal compound at the detection point is different from the orientation state of the liquid crystal compound in the region surrounding the detection point. [8] A liquid crystal film according to any one of [1] to [6], wherein the liquid crystal film further comprises a resin film, and a detection point is provided in the resin film. [9] A liquid crystal film having a lens region formed using a composition containing a liquid crystal compound, the lens region having a liquid crystal orientation pattern radially from the inside to the outside, in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction in the plane, and two or more detectable detection points either inside or outside the lens region, wherein the center point of the lens region is determined by the distance from the two or more detection points.

[0012] According to the present invention, a liquid crystal film having a liquid crystal layer having a lens region can be provided in which the optical center point of the lens region can be easily identified, a method for identifying the center position of the lens region, and a laminate with excellent resistance to humid heat can be provided.

[0013] Figure 1 is a conceptual diagram showing an example of the liquid crystal film of the present invention. Figure 2 is a diagram illustrating the relationship between the detection point and the center point in the liquid crystal film shown in Figure 1. Figure 3 is a conceptual diagram showing another example of the liquid crystal film of the present invention. Figure 4 is a conceptual diagram showing another example of the liquid crystal film of the present invention. Figure 5 is a conceptual diagram showing another example of the liquid crystal film of the present invention. Figure 6 is a conceptual diagram showing another example of the liquid crystal film of the present invention. Figure 7 is a conceptual diagram showing another example of the liquid crystal film of the present invention. Figure 8 is a conceptual cross-sectional view showing an example of the liquid crystal film of the present invention. Figure 9 is a conceptual cross-sectional view showing another example of the liquid crystal film of the present invention. Figure 10 is a conceptual plan view showing an example of the lens region of the liquid crystal film of the present invention. Figure 11 is a cross-sectional view of the lens region shown in Figure 10. Figure 12 is a conceptual diagram showing an optical anisotropy layer for explaining the lens region. Figure 13 is a conceptual diagram for explaining the function of the optical anisotropy layer shown in Figure 12. Figure 14 is a conceptual diagram for explaining the function of the optical anisotropy layer shown in Figure 12. Figure 15 is a conceptual diagram showing an example of an exposure apparatus for exposing an alignment film to orient a lens region. Figure 16 is a conceptual cross-sectional view showing another example of a lens region.

[0014] The liquid crystal film of the present invention and a method for identifying the center point of the lens region of the liquid crystal film will be described in detail below based on preferred embodiments shown in the attached drawings.

[0015] The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0016] Furthermore, the following diagrams are all conceptual diagrams intended to explain the present invention. Therefore, the shape, size, thickness, and positional relationships of each component in each diagram do not necessarily correspond to those of actual objects.

[0017] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0018] In this specification, unless otherwise specified, angles such as "45°", "parallel", "perpendicular", or "orthogonal" mean that the difference from the exact angle is within 5 degrees. Preferably, the difference from the exact angle is less than 3 degrees, and more preferably less than 1 degree.

[0019] In this specification, terms such as “same” and “equal” include a margin of error that is generally accepted in the applicable art.

[0020] [Liquid Crystal Film] The liquid crystal film of the present invention is a liquid crystal film having a liquid crystal layer formed using a composition containing a liquid crystal compound, wherein the liquid crystal layer has a lens region having a liquid crystal orientation pattern radially from the inside to the outside, in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane, and has two or more detectable detection points either inside or outside the lens region, and the center point of the lens region is defined by the distance from the two or more detection points.

[0021] Figure 1 conceptually shows an example of the liquid crystal film of the present invention. Figure 2 shows a magnified view of a portion of the liquid crystal film shown in Figure 1 that includes one lens region. Figure 1 is a plan view of the liquid crystal film 10a viewed from a direction perpendicular to the main surface. The main surface is the largest surface of the sheet-like material (plate-like material, film-like material).

[0022] The liquid crystal film 10a shown in Figure 1 has a liquid crystal layer 12 formed using a composition containing a liquid crystal compound. The liquid crystal layer 12 has nine lens regions 16, nine non-interference exposure regions 18 surrounding each lens region 16, an unaligned region 14, and two detection points 20a and 20b corresponding to each lens region 16. In other words, the liquid crystal film 10a shown in Figure 1 has 18 detection points. In the liquid crystal layer 12, the lens regions 16, non-interference exposure regions 18, unaligned regions 14, and detection points 20a and 20b are formed by different orientation states of the liquid crystal compound.

[0023] In the example shown in Figure 1, each lens region 16 is approximately square in shape with curved corners. Furthermore, the multiple lens regions 16 are arranged in a plane direction of the main surface of the liquid crystal layer 12, with three in the left-right direction and three in the up-down direction. The multiple lens regions 16 are also spaced apart in the plane direction.

[0024] Each lens region 16 has a liquid crystal alignment pattern that radiates from the inside outward, in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane. In a lens region 16 having such a liquid crystal alignment pattern, the lines connecting liquid crystal compounds with the same optical axis orientation are circular, and it can be said that there is a concentric pattern in which circular line segments are arranged concentrically. In other words, within the lens region 16, the liquid crystal compounds are oriented in a radial liquid crystal alignment pattern.

[0025] Such a lens region 16 acts as a condensing lens (convex lens) that focuses one type of circularly polarized light, and as a diverging lens (concave lens) that diverges the other type of circularly polarized light. Whether the lens region 16 acts as a condensing lens or a diverging lens depends on the polarization state of the incident light and the rotation direction of the optical axis in the liquid crystal alignment pattern. Furthermore, the lens region 16 reverses the rotation direction of the circularly polarized light that has passed through the lens region 16. The configuration of the lens region 16 will be described later.

[0026] The lens region 16, which has a lensing effect in this manner, has an optical center point P0 of the lens. In this invention, the center point is defined as the point where the optical axis of the lens and the lens region 16 intersect in the planar direction. In the case of a lens region 16 having a radial liquid crystal alignment pattern, the center point P0 of the lens is the point where multiple directions in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating intersect. Furthermore, in the examples shown in Figures 1 and 2, and in Figure 3 described later, the geometric center of the lens region 16 and the position of the optical center point P0 coincide.

[0027] The non-interference exposure region 18 is a frame-shaped region surrounding each lens region 16 in a plan view (when viewed from a direction perpendicular to the main surface of the liquid crystal layer). In the example shown in Figure 1, the non-interference exposure region 18 surrounds the lens region 16 with a constant width.

[0028] The non-interference exposure region 18 is a region formed on the alignment film that is exposed with only one light beam instead of being subjected to interference exposure with two light beams during exposure of the alignment film for forming the lens region 16, which will be described later. In such a non-interference exposure region 18, the liquid crystal compound is not aligned in the aforementioned liquid crystal alignment pattern, but is aligned in a different alignment state. For example, in the non-interference exposure region 18, the liquid crystal compound is uniaxially aligned.

[0029] The non-aligned region 14 is a region surrounding each of the lens region 16 and the non-interference exposure region 18 in a plan view.

[0030] The non-aligned region 14 is a region formed on the alignment film that is not exposed by either of the two light beams during exposure of the alignment film for forming the lens region 16, which will be described later. In such a non-aligned region 14, the liquid crystal compound is not aligned, that is, the orientation of the liquid crystal compound is random.

[0031] The detection points 20a and 20b are detectable marks, and are provided either inside the lens region 16 or outside the lens region 16 in the in-plane direction. In the examples shown in Figure 1 and Figure 2, the detection points 20a and 20b are provided in the non-interference exposure region 18 outside the lens region 16 in the in-plane direction.

[0032] At detection points 20a and 20b, the liquid crystal compound is oriented in a different orientation than the surrounding region. In the examples shown in Figures 1 and 2, the area surrounding detection points 20a and 20b is the non-coherent exposure region 18, so the liquid crystal compound at detection points 20a and 20b is oriented in a different orientation than the liquid crystal compound within the non-coherent exposure region 18. For example, if the liquid crystal compound within the non-coherent exposure region 18 is uniaxially oriented, the orientation of the liquid crystal compound at detection points 20a and 20b may be unoriented (random orientation), uniaxially oriented in a different direction from the non-coherent exposure region 18, or uniaxially oriented in the same direction as the non-coherent exposure region 18, but with disordered orientation.

[0033] For example, if the liquid crystal compound in the non-coherent exposure region 18 is uniaxially oriented, and the liquid crystal compound at detection points 20a and 20b is unoriented, the non-coherent exposure region 18 is highly transparent and visible to the naked eye, while the unoriented detection points 20a and 20b are less transparent and visible. Therefore, detection points 20a and 20b can be easily detected without the need to combine them with polarizing filters or the like.

[0034] Furthermore, in the examples shown in Figures 1 and 2, the detection points 20a and 20b are located on opposite vertices of the diagonal of the roughly square-shaped lens region 16. Therefore, the center point P0 of the lens region 16 lies between the detection points 20a and 20b on the line segment L connecting the detection points 20a and 20b.

[0035] Here, the center point P0 is defined by the distance from the two detection points 20a and 20b. Specifically, in the example shown in Figure 2, if R1 is the distance from detection point 20a to center point P0, and R2 is the distance from detection point 20b to center point P0, then one intersection point between the curve with radius R1 from detection point 20a and the curve with radius R2 from detection point 20b coincides with the center point P0. Therefore, by detecting detection points 20a and 20b and using the distance information from each of the previously recognized detection points 20a and 20b to center point P0, the center point P0 can be identified by finding the intersection point between the curve with radius R1 from detection point 20a and the curve with radius R2 from detection point 20b.

[0036] As mentioned above, when cutting a liquid crystal film having a liquid crystal layer with a lens region to a size that includes the lens region, or when laminating it onto other optical elements, high-precision alignment is necessary. For example, it is desirable to use the center point of the lens region as a reference point to cut the liquid crystal film to the desired size or to align and laminate it with other optical elements. However, a liquid crystal layer formed using a liquid crystal composition containing a liquid crystal compound is superficially a flat film, and exhibits lens action due to the action of the liquid crystal alignment pattern, so the center (for example, the apex of the convex in the case of a convex lens) cannot be visually observed like a typical lens. Therefore, in order to detect the center point of the lens region, it is necessary to combine it with a polarizing filter or the like and assemble an optical system specifically for that liquid crystal film, making it difficult to easily identify.

[0037] In contrast, the liquid crystal film 10a of the present invention has two or more detectable detection points, and the center point of the lens region 16 is defined by the distance from the two or more detection points. Therefore, as described above, by detecting two or more detection points, the center point P0 can be identified by determining the intersection point that is at a predetermined distance from each detection point based on the distance information from each detection point to the center point P0, which is recognized in advance.

[0038] In the example shown in Figure 2, the shape of the lens region 16 is approximately square, but it is not limited to this, and can be approximately circular, approximately rectangular, approximately polygonal, or irregular in shape, depending on the device into which the liquid crystal film is incorporated.

[0039] Furthermore, in the example shown in Figure 2, the optical center point P0 of the lens region 16 is assumed to coincide approximately with the geometric center point of the lens region 16, but this is not the only limitation, and the optical center point P0 of the lens region 16 and the geometric center point of the lens region 16 may be misaligned.

[0040] Furthermore, in the example shown in Figure 2, the two detection points are arranged on the diagonal of the lens region 16, but this configuration is not limited to this, and they may be arranged in any position. For example, as shown in Figure 3, they may be arranged on each of the two opposing sides of the lens region 16. In the example shown in Figure 3, detection point 20a is arranged in the non-coherent exposure region 18 on the upper side of the lens region 16, and detection point 20b is arranged in the non-coherent exposure region 18 on the lower side of the lens region 16. Also, detection points 20a and 20b are arranged on the line bisector that divides the lens region 16 in half horizontally. In addition, the center point P0 of the lens region 16 lies on the line segment L connecting detection point 20a and detection point 20b.

[0041] Furthermore, in the example shown in Figure 4, detection point 20a is located in the non-coherent exposure region 18 on the upper side of the lens region 16, and detection point 20b is located in the non-coherent exposure region 18 on the left side of the lens region 16. Also, detection point 20a is located in a position that overlaps with the center point P0 in the left-right direction of the figure, and detection point 20b is located in a position that overlaps with the center point P0 in the up-down direction of the figure. In this case, the center point P0 of the lens region 16 does not lie on the line segment connecting detection point 20a and detection point 20b. If the distance from detection point 20a to center point P0 is R1, and the distance from detection point 20b to center point P0 is R2, then there are two intersection points between the curve with radius R1 from detection point 20a and the curve with radius R2 from detection point 20b, but of the two intersection points, the intersection point located within the lens region 16 coincides with the center point P0. Therefore, even if there are two detection points and the center point P0 of the lens region 16 does not lie on the line segment connecting the two detection points, the center point P0 of the lens region 16 is defined by the distance from the two detection points 20a and 20b.

[0042] Furthermore, in the examples shown in Figures 2 to 4, the liquid crystal film is configured to have two detection points, but it may have three or more detection points. Figure 5 conceptually shows another example of the liquid crystal film of the present invention.

[0043] In the example shown in Figure 5, detection point 20a is located in the non-coherent exposure region 18 on the upper side of the lens region 16, detection point 20b is located in the non-coherent exposure region 18 on the lower left corner of the lens region 16, and detection point 20c is located in the non-coherent exposure region 18 on the lower right corner of the lens region 16. If R1 is the distance from detection point 20a to the center point P0, R2 is the distance from detection point 20b to the center point P0, and R3 is the distance from detection point 20c to the center point P0, then the intersection point where the curve with radius R1 from detection point 20a, the curve with radius R2 from detection point 20b, and the curve with radius R3 from detection point 20c intersect coincides with the center point P0. Therefore, the center point P0 of the lens region 16 is defined by the distances from the three detection points 20a to 20c.

[0044] Here, the distance from each detection point to the center point P0 may be the same or different. For example, in the examples shown in Figure 2 and Figure 3, the distance R1 from detection point 20a to the center point P0 and the distance R2 from detection point 20b to the center point P0 are approximately the same. Also, in the example shown in Figure 4, the distance R1 from detection point 20a to the center point P0 and the distance R2 from detection point 20b to the center point P0 are approximately the same. Furthermore, in the example shown in Figure 5, the distance R1 from detection point 20a to the center point P0, the distance R2 from detection point 20b to the center point P0, and the distance R3 from detection point 20c to the center point P0 are different, while the distance R2 from detection point 20b to the center point P0 and the distance R3 from detection point 20c to the center point P0 are approximately the same.

[0045] Furthermore, in the examples shown in Figures 1 to 5, the detection points are all located within the non-interferential exposure region 18, but this is not the only option. As shown in the example in Figure 6, the detection points may be located within the lens region 16, or as shown in the example in Figure 7, the detection points may be located within the un-oriented region 14. Also, two or more detection points may be located in different regions. For example, one detection point may be located in the non-interferential exposure region 18, and the other detection point may be located in the lens region 16. It is preferable that the detection points be located outside the lens region 16 (in the un-oriented region 14 or the non-interferential exposure region 18).

[0046] In the example shown in Figure 6, the two detection points 20a and 20b are located near opposing corners within the lens region 16, on the diagonals of the roughly square-shaped lens region 16. The center point P0 of the lens region 16 lies on the line segment L connecting the two detection points 20a and 20b.

[0047] Furthermore, if the detection point is located in the lens region 16, it is preferable that the detection point be located far from the center point P0 in order to reduce the influence on the lens action.

[0048] Furthermore, in the example shown in Figure 1, the liquid crystal layer 12 of the liquid crystal film 10a is provided with a lens region 16, an unaligned region 14, a non-interferential exposure region 18, and a detection point. However, it is not limited to this, as long as it has at least a lens region 16 and a detection point. That is, the liquid crystal layer 12 may have a configuration that does not have a non-interferential exposure region 18 but has a lens region 16, an unaligned region 14, and a detection point; or it may have a configuration that does not have an unaligned region 14 but has a lens region 16, a non-interferential exposure region 18, and a detection point; or it may have a configuration that does not have an unaligned region 14 or a non-interferential exposure region 18 but has only a lens region 16 and a detection point.

[0049] Furthermore, although the example shown in Figure 1 assumes that the liquid crystal layer 12 of the liquid crystal film 10a has nine lens regions 16, it is not limited to this, and the liquid crystal layer 12 of the liquid crystal film 10a may have one lens region 16, or it may have two to eight, or even ten or more lens regions 16.

[0050] Furthermore, in the example shown in Figure 1, the multiple lens regions 16 of the liquid crystal layer 12 of the liquid crystal film 10a are substantially the same shape and size, but this is not limited to this, and when the liquid crystal layer 12 of the liquid crystal film 10a has multiple lens regions 16, the shape and / or size of each lens region 16 may be different from one another.

[0051] Furthermore, if the liquid crystal layer 12 of the liquid crystal film 10a has multiple lens regions 16, the orientation of the liquid crystal compounds in each lens region 16 may be the same or different from each other. That is, the period of one cycle in the liquid crystal orientation pattern of each lens region 16, and the rotation direction of the optical axis along one direction may be the same or different from each other.

[0052] Furthermore, as will be described later, in the lens region 16 of the liquid crystal layer 12, the liquid crystal compounds may be oriented in the same direction in the thickness direction, or they may be cholesteric liquid crystal oriented. When the liquid crystal layer 12 of the liquid crystal film 10a has multiple lens regions 16, the orientation of the liquid crystal compounds in the thickness direction of each lens region 16 may be the same or different from each other. That is, for example, in one lens region 16, the liquid crystal compounds may be oriented in the same direction in the thickness direction, while in another lens region 16, the liquid crystal compounds may be cholesteric liquid crystal oriented in the thickness direction. Also, when the liquid crystal compounds are cholesteric liquid crystal oriented in multiple lens regions 16, the helical pitch of the cholesteric liquid crystal phase may be the same or different from each other.

[0053] Furthermore, if the liquid crystal layer 12 of the liquid crystal film 10a has multiple lens regions 16, there are no particular restrictions on the arrangement of the multiple lens regions 16.

[0054] Furthermore, if the liquid crystal layer 12 of the liquid crystal film 10a has multiple lens regions 16, the arrangement and number of two or more detection points corresponding to each lens region 16 may be the same or different. For example, the arrangement of detection points corresponding to one of the multiple lens regions 16 may be as shown in Figure 2, and the arrangement of detection points corresponding to another lens region 16 may be as shown in Figure 5.

[0055] Furthermore, in the examples shown in Figures 2 and 3, when the center point P0 of the lens region 16 lies on the line segment L connecting the two detection points, it is assumed that the center point P0 lies between the two detection points. However, the explanation is not limited to this, and the center point P0 may also be located outside the two detection points on the line segment L. In other words, the other detection point may be located between the center point P0 and one of the detection points.

[0056] Further, in the example shown in Figure 1, the liquid crystal layer 12 of the liquid crystal film 10a is configured to have a plurality of sets of combinations of two or more detection points corresponding to each of the lens regions 16 in the case where the liquid crystal layer 12 has a plurality of lens regions 16, but the present invention is not limited thereto.

[0057] Figure 7 conceptually shows another example of the liquid crystal film of the present invention.

[0058] The liquid crystal film 10b shown in Figure 7 has a liquid crystal layer 12 formed using a composition containing a liquid crystal compound, and the liquid crystal layer 12 has nine lens regions 16 (16a to 16i), nine non-interfering exposure regions 18 respectively surrounding each of the lens regions 16, an unaligned region 14, and detection points 20a and 20b. That is, the liquid crystal film 10b shown in Figure 7 has two detection points. Note that the liquid crystal film 10b shown in Figure 7 has the same configuration as the liquid crystal film 10a shown in Figure 1 except for the difference in the number of detection points, and therefore the following description will focus mainly on the different parts.

[0059] The liquid crystal film 10b shown in Figure 7 has a detection point 20a in the unaligned region 14 on the upper side of the lens region 16a at the upper left in the figure, and has a detection point 20b in the unaligned region 14 on the left side of the lens region 16a.

[0060] In such a liquid crystal film 10b, the center point of each of the lens regions 16a to 16i is defined by the distances from the detection point 20a and the detection point 20b.

[0061] That is, the center point P of the lens region 16a a0 is defined by the distance R from the detection point 20a a1 and the distance R from the detection point 20b a2 . Further, the center point P of the lens region 16b b0 is defined by the distance R from the detection point 20a b1 and the distance R from the detection point 20b b2 . Further, the center point P of the lens region 16c c0 is defined by the distance R from the detection point 20a c1 and the distance R from the detection point 20b c2 . Further, the center point P of the lens region 16d d0This is the distance R from the detection point 20a. d1 , and the distance R from detection point 20b. d2 It is defined as follows. Also, the center point P of the lens region 16e e0 This is the distance R from the detection point 20a. e1 , and the distance R from detection point 20b. e2 It is defined as follows. Also, the center point P of the lens region 16f f0 This is the distance R from the detection point 20a. f1 , and the distance R from detection point 20b. f2 It is defined as follows. Also, the center point P of the lens region 16g g0 This is the distance R from the detection point 20a. g1 , and the distance R from detection point 20b. g2 It is defined as follows. Also, the center point P of the lens region 16h h0 This is the distance R from the detection point 20a. h1 , and the distance R from detection point 20b. h2 It is defined as follows. Also, the center point P of the lens region 16i i0 This is the distance R from the detection point 20a. i1 , and the distance R from detection point 20b. i2 It is defined as follows.

[0062] Thus, when the liquid crystal layer 12 of the liquid crystal film 10b has multiple lens regions 16, the liquid crystal film 10b may have only one set of two or more detection points for defining the center point of each lens region 16.

[0063] Furthermore, in cases where the liquid crystal layer 12 of the liquid crystal film has multiple lens regions 16, the liquid crystal film may have a configuration that includes a combination of two or more detection points for defining the center point of at least one lens region 16, and another combination of two or more detection points for defining the center point of another at least one lens region 16. In other words, the number of lens regions 16 in the liquid crystal layer 12 of the liquid crystal film may be different from the number of combinations of two or more detection points.

[0064] In the examples described above, the detection point is assumed to be located on the liquid crystal layer 12, but this is not the only option. This point will be explained using Figures 8 and 9.

[0065] First, the case in which the detection point is provided in the liquid crystal layer 12 will be explained using Figure 8. Figure 8 is a conceptual cross-sectional view showing an example of the liquid crystal film of the present invention. Figure 8 can be said to be, for example, a cross-sectional view along the line segment L in Figure 2.

[0066] The liquid crystal film 10c shown in Figure 8 has a liquid crystal layer 12, which includes a lens region 16, a non-interference exposure region 18 surrounding the lens region 16, and detection points 20a and 20b provided corresponding to the lens region 16.

[0067] As shown in Figure 8, when detection points 20a and 20b are provided in the liquid crystal layer 12, as described above, the orientation state of the liquid crystal compound in the region where the detection points 20a and 20b are located is different from the orientation state of the liquid crystal compound in the region surrounding the detection points 20a and 20b (non-coherent exposure region 18 in the illustrated example). As a result, for example, the light transmittance is different between the detection points 20a and 20b and the non-coherent exposure region 18, so the detection points 20a and 20b can be easily detected by visual inspection.

[0068] Next, we will explain the case where the detection point is provided in a layer other than the liquid crystal layer 12 using Figure 9. Figure 9 is a conceptual cross-sectional view showing another example of the liquid crystal film of the present invention.

[0069] The liquid crystal film 10d shown in Figure 9 has a liquid crystal layer 12 and a resin film 22 laminated on the liquid crystal layer 12. The liquid crystal layer 12 has a lens region 16 and a non-interference exposure region 18 surrounding the lens region 16. Detection points 20a and 20b are provided on one surface of the resin film 22.

[0070] Thus, if the liquid crystal film has another layer in addition to the liquid crystal layer 12, detection points 20a and 20b may be provided in this other layer.

[0071] In the example shown in Figure 9, the detection points 20a and 20b are provided on the side of the resin film 22 facing the liquid crystal layer 12, but the method is not limited to this, and they may also be provided on the side of the resin film 22 opposite to the liquid crystal layer 12.

[0072] Furthermore, in the example shown in Figure 9, the detection points 20a and 20b are located in positions that overlap with the non-interferential exposure region 18 in the planar direction, but are not limited to this. They may also be located in positions that overlap with the lens region 16, or in positions that overlap with the un-oriented region 14.

[0073] The resin film 22 is, for example, a support for forming the liquid crystal layer 12, and a protective film for protecting the liquid crystal layer 12. The liquid crystal layer 12 and the resin film 22 may be in direct contact, or they may be laminated with other layers in between. For example, if the resin film 22 is a support for forming the liquid crystal layer 12, it may have an alignment layer between the liquid crystal layer 12 and the support. Also, for example, if the resin film 22 is a protective film for protecting the liquid crystal layer 12, it may have an adhesive layer between the liquid crystal layer 12 and the protective film for attaching the protective film to the liquid crystal layer 12. The protective film may also have an adhesive layer.

[0074] Furthermore, it is preferable that the resin film 22 is peelable from the liquid crystal layer 12. For example, when laminating the liquid crystal film onto another optical element, the center point of the lens region 16 may be identified from the detection points provided on the resin film 22, and after aligning and laminating with the other optical element, the resin film 22 may be peeled off from the liquid crystal layer 12.

[0075] The components of the resin film of the present invention will be described below.

[0076] <Liquid Crystal Layer> The liquid crystal layer 12 is formed using a composition containing a liquid crystal compound and has a lens region 16 having a liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane.

[0077] <<Lens Region>> Figure 10 is a conceptual plan view showing an example of a lens region 16 of the liquid crystal layer 12. Figure 11 is a conceptual cross-sectional view showing the lens region 16. Figure 11 can be said to be a cross-sectional view along one direction in the liquid crystal alignment pattern of the lens region 16 shown in Figure 10. Therefore, Figure 10 is a view of the lens region 16 of Figure 11 from above. Note that in Figures 10 and 11, a rod-shaped liquid crystal compound is exemplified as the liquid crystal compound 30, so the direction of the optical axis coincides with the longitudinal direction of the liquid crystal compound 30.

[0078] Furthermore, although Figure 10 shows only the liquid crystal compound 30 on the surface of the alignment film, as shown in Figure 11, the lens region 16 has a structure in which liquid crystal compounds 30 oriented in the same direction as the liquid crystal compound 30 on the surface of the alignment film are stacked in the thickness direction.

[0079] Furthermore, in the example shown in Figure 10, the optical center point of the lens region 16 coincides with the geometric center.

[0080] Furthermore, Figure 11 shows a laminate having a lens region 16 (liquid crystal layer 12), as well as a support 22a and an alignment film 24 used when forming the lens region 16 (liquid crystal layer 12). As mentioned above, the liquid crystal film of the present invention may be a liquid crystal layer 12 having a lens region 16 alone, or it may be a laminate including a support 22a and an alignment film 24 in addition to the liquid crystal layer 12.

[0081] As shown in Figure 10, in the in-plane direction of the lens region 16, the orientation of the optical axis of the liquid crystal compound 30 changes while continuously rotating along a number of directions extending outward from the center of the lens region 16, for example, the direction indicated by arrow A1, the direction indicated by arrow A2, the direction indicated by arrow A3, the direction indicated by arrow A4, and so on. Each of the directions indicated by arrow A1, A2, A3, A4, and so on is a unidirectional direction in this invention. That is, the lens region has a number of unidirectional directions radiating from the inside outward.

[0082] Furthermore, in the lens region 16, the rotation direction of the optical axis of the liquid crystal compound 30 when viewed in the direction along each arrow is the same in all directions (unidirectional). In the illustrated example, the rotation direction of the optical axis of the liquid crystal compound 30 is counterclockwise in all directions indicated by arrows A1, A2, A3, and A4.

[0083] In other words, if we consider arrows A1 and A4 as a single straight line, the direction of rotation of the optical axis of the liquid crystal compound 30 reverses at the center of the lens region 16 along this straight line. For example, when viewed from the right (in the direction of arrow A1) along the straight line formed by arrows A1 and A4, the optical axis of the liquid crystal compound 30 initially rotates clockwise from the outside of the lens region 16 toward the center, the direction of rotation reverses at the center of the lens region 16, and thereafter rotates counterclockwise from the center of the lens region 16 toward the outside.

[0084] In such a lens region 16, the lines connecting the liquid crystal compounds 30 whose optical axes are oriented in the same direction are circular, and it can be said that it has a concentric pattern in which circular line segments are arranged concentrically.

[0085] The optical axis derived from the liquid crystal compound 30 is the axis in the liquid crystal compound 30 where the refractive index is highest, also known as the slow axis. For example, if the liquid crystal compound 30 is a rod-shaped liquid crystal compound, the optical axis is aligned with the long axis of the rod shape.

[0086] In the following explanation, the optical axis derived from the liquid crystal compound 30 will also be referred to as the "optical axis of the liquid crystal compound 30" or simply the "optical axis." Furthermore, "the direction of the optical axis 30A is rotating" will also be simply referred to as "the optical axis 30A is rotating."

[0087] Preferably, in the lens region 16, the liquid crystal alignment pattern is such that, when the length of one period is defined as the length of a 180° rotation of the optical axis direction originating from the liquid crystal compound in one direction in which the direction of the optical axis of the liquid crystal compound 30 changes while continuously rotating, the length of one period gradually decreases from the inside to the outside.

[0088] Circularly polarized light incident on a lens region 16 having such a liquid crystal alignment pattern is diffracted in localized regions of the optical anisotropy layer. In this case, the direction in which the circularly polarized light is diffracted in each region is along the direction in which the orientation of the optical axis of the liquid crystal compound 30 changes as it rotates continuously. Furthermore, the diffraction direction depends on the direction of rotation of the optical axis of the liquid crystal compound 30, which rotates along this unidirectional direction. In addition, the diffraction angle becomes larger as the period becomes shorter.

[0089] Therefore, a lens region 16 having such a radial liquid crystal alignment pattern, that is, a liquid crystal alignment pattern having a radial direction in which the optical axis changes as it continuously rotates, can transmit incident light (light beam) by diverging or focusing it, depending on the rotation direction of the optical axis of the liquid crystal compound 30 and the rotation direction of the incident circularly polarized light.

[0090] The lens region 16 will now be described with reference to the optical anisotropy layer 16A shown in Figure 12. Figure 12 is a conceptual plan view of the optical anisotropy layer 16A having a liquid crystal alignment pattern that changes as the optical axis 30A rotates continuously in one direction indicated by arrow A.

[0091] In the lens region 16 shown in Figure 10, even in a liquid crystal alignment pattern having a radial direction from the inside to the outside in which the optical axis changes while continuously rotating, the same optical effects as those of the liquid crystal alignment pattern shown in Figure 12 are exhibited in the direction in which the optical axis changes while continuously rotating (such as the directions of arrows A1 to A4). That is, in the lens region 16 shown in Figure 10, the directions of arrows A1 to A4 in the radial liquid crystal alignment pattern correspond to the direction of arrow A in Figure 12.

[0092] In the optically anisotropic layer 16A, the liquid crystal compound 30 is arranged two-dimensionally in a plane parallel to the direction indicated by arrow A and the Y direction which is perpendicular to the direction of arrow A. In Figures 13 and 14, which will be described later, the Y direction is perpendicular to the plane of the paper.

[0093] In the following explanation, "the one direction indicated by arrow A" will also simply be referred to as "the direction of arrow A."

[0094] In the lens region 16 shown in Figure 10, the circumferential direction in the radial liquid crystal alignment pattern corresponds to the Y direction in Figure 12.

[0095] The plan view is a view of the optically anisotropic layer 16A from the thickness direction. In other words, it is a view of the optically anisotropic layer 16A from a direction perpendicular to the main surface. The main surface is the largest surface in a sheet-like material (plate-like material, film, layer).

[0096] Furthermore, in Figure 12, in order to clearly show the structure of the optically anisotropic layer 16A, similar to Figure 10, only the liquid crystal compound 30 on the surface of the alignment film 24 is shown. However, this optically anisotropic layer 16A also has a structure in the thickness direction in which the liquid crystal compound 30 is stacked from the liquid crystal compound 30 on the surface of the alignment film, as shown in Figure 11.

[0097] The optically anisotropic layer 16A has a liquid crystal orientation pattern in which the orientation of the optical axis 30A originating from the liquid crystal compound 30 changes while continuously rotating along the direction of arrow A within the plane of the optically anisotropic layer 16A.

[0098] The statement that the orientation of the optical axis 30A of the liquid crystal compound 30 changes while continuously rotating in the direction of arrow A (a predetermined one direction) means that, specifically, the angle between the optical axis 30A of the liquid crystal compounds 30 arranged along the direction of arrow A and the direction of arrow A differs depending on the position in the direction of arrow A, and that the angle between the optical axis 30A and the direction of arrow A changes sequentially from θ to θ+180° or θ-180° along the direction of arrow A. In other words, as shown in Figure 12, the multiple liquid crystal compounds 30 arranged along the direction of arrow A are arranged such that the optical axis 30A changes while rotating in the direction of arrow A by a fixed angle.

[0099] Furthermore, the difference in angle between the optical axes 30A of adjacent liquid crystal compounds 30 in the direction of arrow A is preferably 45° or less, more preferably 15° or less, and even more preferably a smaller angle.

[0100] Furthermore, in the present invention, the rotation direction of the optical axis 30A of the liquid crystal compound 30 in the direction of arrow A is assumed to be such that the liquid crystal compound 30 (optical axis 30A) rotates in a direction that reduces the angle between the optical axes 30A of adjacent liquid crystal compounds 30 in the direction of arrow A. Therefore, in the optically anisotropic layer 16A shown in Figure 12, the optical axis 30A of the liquid crystal compound 30 rotates counterclockwise along the direction of arrow A.

[0101] On the other hand, in the liquid crystal compound 30 that forms the optical anisotropy layer 16A, in the Y direction perpendicular to the direction of arrow A, that is, in the Y direction perpendicular to the direction in which the optical axis 30A rotates continuously, the liquid crystal compound 30 with the same orientation of the optical axis 30A is arranged at equal intervals.

[0102] In other words, in the liquid crystal compound 30 that forms the optical anisotropy layer 16A, the angle between the direction of the optical axis 30A and the direction of arrow A is equal for liquid crystal compounds 30 arranged in the Y direction.

[0103] In the lens region 16 shown in Figure 10, a region is formed in the shape of an annular ring with its center coinciding, where the orientation of the optical axis 30A is the same.

[0104] In a liquid crystal alignment pattern where the optical axis 30A rotates continuously in one direction, the length (distance) of the 180° rotation of the optical axis 30A of the liquid crystal compound 30 is defined as the length Λ of one period in the liquid crystal alignment pattern. That is, in the case of the optically anisotropic layer 16A shown in Figure 12, the length (distance) of the 180° rotation of the optical axis 30A of the liquid crystal compound 30 in the direction of arrow A, where the orientation of the optical axis 30A changes continuously within the plane, is defined as the length Λ of one period in the liquid crystal alignment pattern. In other words, the length of one period in the liquid crystal alignment pattern is defined by the distance from θ to θ + 180° in the angle between the optical axis 30A of the liquid crystal compound 30 and the direction of arrow A.

[0105] In other words, the length of one period Λ is defined as the distance between the centers in the direction of arrow A of two liquid crystal compounds 30 whose angles with respect to arrow A are equal. Specifically, as shown in Figure 12, the length of one period Λ is defined as the distance between the centers in the direction of arrow A of two liquid crystal compounds 30 whose directions of arrow A coincide with the direction of the optical axis 30A. In the following explanation, this length of one period Λ will also be referred to as "period Λ".

[0106] In the optically anisotropic layer 16A, the liquid crystal alignment pattern repeats this one period Λ in one direction, where the direction of arrow A, i.e., the direction of the optical axis 30A, continuously rotates and changes.

[0107] As described above, in the optically anisotropic layer 16A, the liquid crystal compounds arranged in the Y direction have an equal angle between the optical axis 30A and the direction of arrow A (one direction in which the orientation of the optical axis of the liquid crystal compound 30 rotates). The region in which the liquid crystal compounds 30 having an equal angle between the optical axis 30A and the direction of arrow A are arranged in the Y direction is defined as region R.

[0108] In this case, the in-plane retardation (Re) value in each region R is preferably half a wavelength, i.e., λ / 2. These in-plane retardations are calculated by the product of the refractive index difference Δn due to the refractive index anisotropy of region R and the thickness of the optical anisotropy layer 16A. Here, the refractive index difference due to the refractive index anisotropy of region R in the optical anisotropy layer 16A is defined as the refractive index difference between the refractive index in the direction of the slow axis in the plane of region R and the refractive index in the direction perpendicular to the direction of the slow axis. That is, the refractive index difference Δn due to the refractive index anisotropy of region R is equal to the difference between the refractive index of the liquid crystal compound 30 in the direction of the optical axis 30A and the refractive index of the liquid crystal compound 30 in the direction perpendicular to the optical axis 30A in the plane of region R. In other words, the above refractive index difference Δn is equal to the refractive index difference of the liquid crystal compound 30.

[0109] In a lens region 16 having a radial pattern of continuous rotation of the optical axis 30A in one direction (such as the directions of arrows A1 to A4), the region where the optical axis 30A is oriented in the same direction and is formed in an annular shape with a coincident center corresponds to region R in Figure 12.

[0110] When circularly polarized light is incident on such an optically anisotropic layer 16A, the light is refracted and the direction of the circular polarization is changed. This effect will be explained using Figures 13 and 14. The optically anisotropic layer 16A is defined as having a product value of λ / 2 between the refractive index difference of the liquid crystal compound 30 and the thickness of the optically anisotropic layer 16A.

[0111] Furthermore, as described above, this effect is exactly the same in the lens region 16, which has a radial direction in which the optical axis 30A rotates continuously.

[0112] As shown in Figure 13, when the product of the refractive index difference of the liquid crystal compound 30 in the optical anisotropy layer 16A and the thickness of the optical anisotropy layer 16A is λ / 2, when left-circularly polarized incident light L1 is incident on the optical anisotropy layer 16A, the incident light L1 passes through the optical anisotropy layer 16A, giving it a phase difference of 180°, and the transmitted light L2 is converted to right-circularly polarized light.

[0113] Furthermore, since the liquid crystal alignment pattern formed in the optical anisotropy layer 16A is a periodic pattern in the direction of arrow A, the transmitted light L2 travels in a direction tilted by a certain angle in the direction of arrow A with respect to the direction of propagation of the incident light L1. In this way, the left-circularly polarized incident light L1 is converted into right-circularly polarized transmitted light L2, which is tilted by a certain angle in the direction of arrow A with respect to the direction of incidence.

[0114] On the other hand, as conceptually shown in Figure 14, when the product of the refractive index difference of the liquid crystal compound 30 in the optical anisotropy layer 16A and the thickness of the optical anisotropy layer 16A is λ / 2, when right-circularly polarized incident light L4 is incident on the optical anisotropy layer 16A, the incident light L4 passes through the optical anisotropy layer 16A, is given a phase difference of 180°, and is converted into left-circularly polarized transmitted light L5.

[0115] Furthermore, since the liquid crystal alignment pattern formed in the optically anisotropic layer 16A is a periodic pattern in the direction of arrow A, the transmitted light L5 travels in a direction tilted by a certain angle in the direction of arrow A with respect to the direction of propagation of the incident light L4. At this time, the transmitted light L5 travels in a different direction from the transmitted light L2, that is, in a direction opposite to the direction of arrow A with respect to the direction of incidence. In this way, the incident light L4 is converted into transmitted light L5 which is left-circularly polarized and tilted by a certain angle in the direction of arrow A with respect to the direction of incidence.

[0116] In the optical anisotropy layer 16A (lens region 16), the in-plane retardation values ​​of the multiple regions R are preferably half the wavelength of the incident light. However, for incident light with a wavelength of 550 nm, the in-plane retardation Re(550) = Δn of the multiple regions R in the optical anisotropy layer 16A is 550 It is preferable that ×d is within the range defined in the following formula (1). Here, Δn 550 Δn is the refractive index difference due to refractive index anisotropy in region R when the wavelength of incident light is 550 nm, and d is the thickness of the optical anisotropy layer 16A (lens region 16). 200 nm ≤ Δn 550 ×d ≤ 350 nm ... (1)

[0117] That is, the in-plane retardation Re(550) = Δn of multiple regions R in the optical anisotropy layer 16A 550 If ×d satisfies equation (1), a sufficient amount of circularly polarized light incident on the optical anisotropic layer 16A can be converted into circularly polarized light traveling in a direction tilted forward or backward with respect to the direction of arrow A.

[0118] Note that while the above equation (1) is for incident light with a wavelength of 550 nm, the in-plane retardation Re(λ) = Δn for multiple regions R of the optical anisotropy layer 16A for incident light with a wavelength of λ nm. λ ×d is preferably within the range defined by the following formula (1-2), and can be set as appropriate: 0.7 × (λ / 2) nm ≤ Δn λ ×d≦1.3×(λ / 2)nm...(1-2)

[0119] The optically anisotropic layer 16A (lens region 16) functions as a so-called λ / 2 plate. However, in the present invention, when a support 22a and an alignment film 24 are present, the laminate comprising these integrally functions as a λ / 2 plate.

[0120] Here, the optical anisotropic layer 16A can adjust the refraction angles of transmitted light L2 and L5 by changing the period Λ of the formed liquid crystal alignment pattern. Specifically, the shorter the period Λ of the liquid crystal alignment pattern, the stronger the interference between light passing through adjacent liquid crystal compounds 30, thereby allowing for greater refraction of transmitted light L2 and L5.

[0121] Furthermore, the angle of refraction of transmitted light L2 and L5 relative to incident light L1 and L4 differs depending on the wavelength of the incident light L1 and L4 (and transmitted light L2 and L5). Specifically, the longer the wavelength of the incident light, the greater the refraction of the transmitted light. That is, when the period Λ of the liquid crystal alignment pattern is the same, if the incident light is red, green, and blue light, the red light is refractioned the most, and the blue light is refractioned the least.

[0122] Furthermore, by reversing the rotation direction of the optical axis 30A of the liquid crystal compound 30, which rotates along the direction of arrow A, the direction of refraction (azimuth direction) of transmitted light can be reversed.

[0123] As described above, in the present invention, it is preferable that in the lens region 16, the period Λ of the liquid crystal alignment pattern gradually shortens from the inside (center) to the outside in one direction of rotation of the optical axis 30A. Therefore, by setting the rotation direction of the optical axis 30A from the inside to the outside so that the light is refracted toward the center of the lens region 16 according to the wavelength and polarization state of the incident light, and by appropriately adjusting the degree of gradual reduction in the length of the period Λ of the liquid crystal alignment pattern, the degree of light focusing toward the center (optical axis) of the lens region 16 can be adjusted. In other words, by greatly gradually reducing the length of the period Λ of the liquid crystal alignment pattern, the lens region 16 can be made to act as a focusing lens (convex lens).

[0124] Furthermore, by setting the polarization state of the incident light and the rotation direction of the optical axis in the liquid crystal alignment pattern, the lens region 16 can be made to act as a diverging lens (concave lens) that emits light by refracting light toward the outside of the lens region 16.

[0125] <<Method for forming the lens region (liquid crystal layer)>> The liquid crystal layer 12 is formed using a liquid crystal composition containing a rod-shaped liquid crystal compound or a disc-shaped liquid crystal compound, and the region having a liquid crystal alignment pattern in which the optical axis of the rod-shaped liquid crystal compound or the optical axis of the disc-shaped liquid crystal compound is oriented as described above becomes the lens region 16. Furthermore, as described above, the liquid crystal layer 12 may also have a non-coherent exposure region 18, an unaligned region 14, and a detection point.

[0126] As an example, a liquid crystal layer 12 having a lens region 16 is formed as follows. First, an alignment film 24 is provided on a support 22a, and interference exposure is performed to form an alignment film 24 having an alignment pattern corresponding to the liquid crystal alignment pattern described above. Next, a liquid crystal composition is applied to the alignment film 24 having an alignment pattern, and the liquid crystal compounds on the alignment pattern are aligned to the liquid crystal alignment pattern and cured to obtain a liquid crystal layer 12 (lens region 16) consisting of a cured layer of liquid crystal composition.

[0127] Furthermore, unaligned regions 14 are formed in the liquid crystal layer 12 on areas of the alignment film 24 that do not have an alignment pattern (regions that were not exposed during exposure). In addition, non-interference exposed regions 18 are formed in the liquid crystal layer 12 on areas of the alignment film 24 that were exposed by only one light beam during interference exposure.

[0128] The liquid crystal composition for forming the liquid crystal layer 12 may contain a rod-shaped liquid crystal compound or a disc-shaped liquid crystal compound, and may also contain other components such as a leveling agent, an orientation control agent, a polymerization initiator, and an orientation aid.

[0129] Furthermore, it is desirable that the lens region 16 of the liquid crystal layer 12 has a broad bandwidth with respect to the wavelength of the incident light, and is preferably constructed using a liquid crystal material with inverse dispersion birefringence. It is also preferable to make the lens region 16 substantially broad with respect to the wavelength of the incident light by imparting a torsion component to the liquid crystal composition or by stacking different liquid crystal layers 12 (lens region 16). For example, a method for realizing a broadband patterned lens region 16 by stacking two lens regions 16 with different torsion directions is shown in Japanese Patent Application Publication No. 2014-089476, and can be preferably used in the present invention.

[0130] ―Rod-shaped liquid crystal compounds― Preferably used rod-shaped liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyanosubstituted phenylpyrimidines, alkoxysubstituted phenylpyrimidines, phenyldioxanes, trans, and alkenylcyclohexylbenzonitriles. In addition to the low molecular weight liquid crystalline molecules mentioned above, high molecular weight liquid crystalline molecules can also be used as rod-shaped liquid crystal compounds.

[0131] In the liquid crystal layer 12, it is more preferable to fix the orientation of the rod-shaped liquid crystal compound by polymerization. Examples of polymerizable rod-shaped liquid crystal compounds include those described in Makromol. Chem., Vol. 190, p. 2255 (1989), Advanced Materials. Compounds described in Volume 5, page 107 (1993), U.S. Patent No. 4683327, No. 5622648, No. 5770107, International Publication Nos. 95 / 022586, 95 / 024455, 97 / 000600, 98 / 023580, 98 / 052905, Japanese Patent Publication No. 1-272551, 6-016616, 7-110469, 11-080081, and Japanese Patent Application No. 2001-064627 can be used. Furthermore, as rod-shaped liquid crystal compounds, those described in, for example, Japanese Patent Publication No. 11-513019 and Japanese Patent Application No. 2007-279688 can also be preferably used.

[0132] —Disk-shaped liquid crystal compounds—As disc-shaped liquid crystal compounds, for example, those described in Japanese Patent Publication No. 2007-108732 and Japanese Patent Publication No. 2010-244038 can be preferably used.

[0133] Furthermore, when a disc-shaped liquid crystal compound is used in the liquid crystal layer 12, the liquid crystal compound 30 rises in the thickness direction in the lens region 16 of the liquid crystal layer 12, and the optical axis 30A derived from the liquid crystal compound is defined as an axis perpendicular to the disc surface, a so-called phase-advancing axis.

[0134] Such a liquid crystal layer 12 (lens region 16) is a flat, sheet-like surface with no irregularities. Furthermore, the liquid crystal layer 12 is thin, with a thickness of 1 to 100 μm.

[0135] <<Support>> The support 22a supports the alignment film 24 and the liquid crystal layer 12.

[0136] The support 22a can be any type of sheet material (film, plate) that can support the alignment film 24 and the liquid crystal layer 12. A transparent support is preferred for the support 22a, and examples include polyacrylic resin films such as polymethyl methacrylate, cellulose resin films such as cellulose triacetate, cycloolefin polymer films (e.g., "Arton" (product name), manufactured by JSR Corporation; "Zeonor" (product name), manufactured by Nippon Zeon Corporation), polyethylene terephthalate (PET), polycarbonate, and polyvinyl chloride. The support is not limited to a flexible film; it may also be a non-flexible substrate such as a glass substrate.

[0137] There are no restrictions on the thickness of the support 22a, and the thickness that can hold the alignment film 24 and the liquid crystal layer 12 should be set appropriately depending on the application of the liquid crystal film and the material used to form the support 22a. The thickness of the support 22a is preferably 1 to 1000 μm, more preferably 3 to 250 μm, and even more preferably 5 to 150 μm.

[0138] Furthermore, the support 22a may be peelable from the liquid crystal layer 12 after its formation.

[0139] Alternatively, a detection point may be provided on the support 22a, and the support 22a may be used as the resin film 22 in the present invention.

[0140] <<Alignment Film>> An alignment film 24 is formed on the surface of the support 22a. The alignment film 24 is an alignment film used to orient the liquid crystal compound 30 into a predetermined liquid crystal alignment pattern when forming the lens region 16 of the liquid crystal layer 12.

[0141] As described above, the lens region 16 of the liquid crystal layer 12 has a liquid crystal alignment pattern that radiates from the inside outward, in which the orientation of the optical axis 30A originating from the liquid crystal compound 30 changes while continuously rotating along one direction in the plane (such as the direction of arrow A1 to arrow A4 described above). Therefore, the alignment film 24 is formed so that the lens region 16 of the liquid crystal layer 12 can form this liquid crystal alignment pattern.

[0142] Various known orientation films 24 can be used. Examples include rubbing films made of organic compounds such as polymers, obliquely deposited films of inorganic compounds, films having microgrooves, and films formed by accumulating Langmuir-Blodgett (LB) films of organic compounds such as ω-tricosanoic acid, dioctadecylmethylammonium chloride, and methyl stearylate using the Langmuir-Blodgett method.

[0143] An oriented film formed by rubbing can be created by rubbing the surface of a polymer layer several times in a specific direction with paper or cloth.

[0144] Preferred materials for use in the orientation film 24 include polyimide, polyvinyl alcohol, polymers having polymerizable groups as described in Japanese Patent Publication No. 9-152509, materials used for forming orientation films as described in Japanese Patent Publication No. 2005-097377, Japanese Patent Publication No. 2005-099228, and Japanese Patent Publication No. 2005-128503.

[0145] Furthermore, as the alignment film 24, a so-called photo-alignment film is preferably used, which is formed by irradiating a photo-alignable material with polarized or unpolarized light to create an alignment film. Specifically, as the alignment film 24, a photo-alignment film formed by coating a photo-alignment material onto a support 22a is preferably used.

[0146] Polarized light irradiation can be applied perpendicularly or obliquely to the photo-alignment film, while unpolarized light irradiation can be applied obliquely to the photo-alignment film.

[0147] Examples of photo-alignment materials used in the photo-alignment film applicable to the present invention include those described in Japanese Patent Publication No. 2006-285197, Japanese Patent Publication No. 2007-076839, Japanese Patent Publication No. 2007-138138, Japanese Patent Publication No. 2007-094071, Japanese Patent Publication No. 2007-121721, Japanese Patent Publication No. 2007-140465, Japanese Patent Publication No. 2007-156439, and Japanese Patent Publication No. 2 Azo compounds described in Japanese Patent Publication No. 007-133184, 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, maleimides having photo-orienting units described in Japanese Patent Publication No. 2002-265541 and Japanese Patent Publication No. 2002-317013 Examples of preferred examples include alkenyl-substituted nadiimide compounds, photocrosslinkable silane derivatives described in Japanese Patent No. 4205195 and Japanese Patent No. 4205198, photocrosslinkable polyimides, photocrosslinkable polyamides and photocrosslinkable esters described in Japanese Patent Publication No. 2003-520878, Japanese Patent Publication No. 2004-529220 and Japanese Patent No. 4162850, and photodimerizable compounds described in Japanese Patent Publication No. 9-118717, Japanese Patent Publication No. 10-506420, Japanese Patent Publication No. 2003-505561, International Publication No. 2010 / 150748, Japanese Patent Publication No. 2013-177561 and Japanese Patent Publication No. 2014-012823, particularly cinnamate compounds, chalcone compounds and coumarin compounds. Among these, azo compounds, photocrosslinkable polyimides, photocrosslinkable polyamides, photocrosslinkable esters, cinnamate compounds, and chalcone compounds are particularly suitable for use.

[0148] There are no restrictions on the thickness of the alignment film 24; the thickness can be appropriately set to obtain the necessary alignment function depending on the material used to form the alignment film 24. The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

[0149] There are no limitations on the method for forming the alignment film 24, and various known methods depending on the material used to form the alignment film 24 can be used. As an example, one method involves coating the alignment film 24 onto the surface of the support 22a, drying it, and then exposing the alignment film 24 with laser light to form an alignment pattern.

[0150] Figure 15 conceptually shows an example of an exposure apparatus that exposes an alignment film 24 to form an alignment film 24 having an alignment pattern.

[0151] The exposure apparatus 80 shown in Figure 15 includes a light source 84 equipped with a laser 82, a polarizing beam splitter 86 that splits the laser light M from the laser 82 into S-polarized MS and P-polarized MP, a mirror 90A arranged in the optical path of the P-polarized MP and a mirror 90B arranged in the optical path of the S-polarized MS, a lens 92 arranged in the optical path of the S-polarized MS, the polarizing beam splitter 94, and a λ / 4 plate 96.

[0152] The P-polarized beam MP, split by the polarizing beam splitter 86, is reflected by the mirror 90A and incident on the polarizing beam splitter 94. On the other hand, the S-polarized beam MS, split by the polarizing beam splitter 86, is reflected by the mirror 90B, focused by the lens 92, and incident on the polarizing beam splitter 94.

[0153] P-polarized MP and S-polarized MS are combined by the polarizing beam splitter 94 and converted into right-circularly polarized and left-circularly polarized beams according to their polarization direction by the λ / 4 plate 96, and then incident on the alignment film 24 on the support 22a.

[0154] Here, the interference between right-circularly polarized and left-circularly polarized light causes the polarization state of the light irradiated onto the alignment film 24 to change periodically in an interference fringe pattern. As you move from the inside to the outside of the concentric circles, the intersection angle between the left-circularly polarized and right-circularly polarized light changes, resulting in an exposure pattern in which the pitch changes from the inside to the outside. As a result, a radial alignment pattern in which the alignment state changes periodically is obtained in the alignment film 24.

[0155] In this exposure apparatus 80, one cycle of the liquid crystal alignment pattern, in which the optical axis of the liquid crystal compound 30 rotates continuously by 180° along one direction, can be controlled by changing the refractive power of the lens 92 (F-number of the lens 92), the focal length of the lens 92, and the distance between the lens 92 and the alignment film 24. Furthermore, by adjusting the refractive power of the lens 92 (F-number of the lens 92), the length of one cycle of the liquid crystal alignment pattern in the direction in which the optical axis rotates continuously can be changed.

[0156] Specifically, the length of one period of the liquid crystal alignment pattern can be changed in one direction of continuous rotation of the optical axis by adjusting the divergence angle of the light (spherical wave) spread by the lens 92, which interferes with the parallel light (plane wave). More specifically, if the refractive power of the lens 92 is weakened, the spherical wave approaches the parallel light, so the length of one period Λ of the liquid crystal alignment pattern gradually shortens from the inside to the outside, and the F number increases. Conversely, if the refractive power of the lens 92 is strengthened, the length of one period Λ of the liquid crystal alignment pattern shortens abruptly from the inside to the outside, and the F number decreases.

[0157] Furthermore, as the exposure apparatus for forming the radial orientation pattern, the exposure apparatus disclosed in International Publication No. 2023 / 101014 may be used.

[0158] As mentioned above, in a liquid crystal film, the alignment film 24 is provided as a preferred embodiment and is not an essential component. For example, by forming a region having an alignment pattern on the support 22a by a rubbing method or a method of processing the support 22a with laser light, the liquid crystal layer 12 can be configured to have a lens region 16 having a liquid crystal alignment pattern in which the orientation of the optical axis 30A originating from the liquid crystal compound 30 changes while continuously rotating radially along one direction.

[0159] Furthermore, the alignment film 24 may be peelable from the liquid crystal layer 12 after its formation.

[0160] Here, when exposing the alignment film 24, it is preferable to define the exposure area using a mask. By defining the exposure area, the lens area 16 of the liquid crystal layer 12 formed on the alignment film 24 can be defined. Specifically, for example, in the exposure apparatus 80 shown in Figure 15, by placing a mask having an opening corresponding to the size and shape of the lens area 16 between the λ / 4 plate 96 and the alignment film 24 and exposing it, an alignment pattern can be formed on the alignment film 24 in an area of ​​a predetermined size and shape.

[0161] Furthermore, when the exposure area of ​​the alignment film 24 is defined using a mask, parallel light (plane wave) is irradiated onto an area of ​​approximately the same size and shape as the opening of the mask, while light that has passed through the lens 92 (spherical wave) is irradiated onto an area larger than the size of the opening of the mask. Therefore, the area of ​​the alignment film 24 of approximately the same size and shape as the opening of the mask is irradiated with both plane and spherical waves, and interference exposure occurs to form an alignment pattern. On the other hand, the area surrounding the area where the alignment pattern is formed is exposed only by spherical waves. In this area, a pattern is formed that aligns the liquid crystal compound to an orientation state different from the liquid crystal alignment pattern described above. Consequently, a non-interference exposure area 18 is formed in the liquid crystal layer 12 formed on this surrounding area.

[0162] The width of the non-coherent exposure region 18 can be appropriately adjusted by the distance between the mask and the alignment film 24, and the divergence angle of the light (spherical wave) spread by the lens 92.

[0163] The method of exposure for the alignment film 24 is not limited to the method described above. Various exposure methods can be used as long as they allow for the formation of an alignment pattern on the alignment film that enables the formation of a lens region 16 on the liquid crystal layer 12. For example, the alignment film 24 may be formed by exposure using a direct laser writing method.

[0164] Furthermore, as shown in Figure 1, when forming a liquid crystal layer 12 having multiple lens regions 16, by repeatedly exposing the alignment film 24 formed on the support 22a to light and moving the support 22a in the in-plane direction, an alignment pattern can be formed in multiple regions within the plane of the alignment film 24, and by forming the liquid crystal layer 12 on the alignment film 24 having multiple alignment patterns, multiple lens regions 16 can be formed in the liquid crystal layer 12.

[0165] <Resin Film> As described above, the liquid crystal film of the present invention may have a resin film 22 in addition to the liquid crystal layer 12.

[0166] As described above, the resin film 22 is, for example, a support 22a for forming the liquid crystal layer 12, and a protective film for protecting the liquid crystal layer 12. The support 22a is as described above.

[0167] Various sheet-like materials (films, plates) can be used as protective films. Examples of protective films include polyester, polyethylene, polyurethane, polycarbonate, polyethylene terephthalate, polycarbonate, and polypropylene.

[0168] There are no restrictions on the thickness of the protective film; it can be set appropriately depending on the application of the liquid crystal film and the material used to form the protective film. The thickness of the protective film is preferably 1 to 1000 μm, more preferably 10 to 500 μm, and even more preferably 50 to 200 μm.

[0169] Furthermore, the protective film may be peelable from the liquid crystal layer 12, and the protective film may be peeled off from the liquid crystal layer 12 after the liquid crystal film has been laminated onto other optical elements.

[0170] <Detection Point> The detection point is a mark used to identify the center point of the lens area 16.

[0171] As mentioned above, the detection point may be provided on the liquid crystal layer 12, or it may be provided on a layer other than the liquid crystal layer 12, such as the resin film 22.

[0172] When a detection point is provided in the liquid crystal layer 12, as described above, the liquid crystal compound within the region of the detection point is oriented to a different orientation than the surrounding region. For example, if the area surrounding the detection point is a non-coherent exposure region 18, and the liquid crystal compound within the non-coherent exposure region 18 is uniaxially oriented, then the orientation of the liquid crystal compound at the detection point should be unoriented (randomly oriented). One method for providing such a detection point is to mask a part of the region corresponding to the non-coherent exposure region 18 when exposing the alignment film 24 described above. Since spherical waves are not irradiated into the masked region, the liquid crystal compound of the liquid crystal layer 12 formed on this region is not oriented, and thus an unoriented (randomly oriented) region (detection point) is formed.

[0173] In this case, the distance from the detection point to the center point P0 of the lens region 16 is determined from the distance between the masked area and the center position of the interference exposure during exposure of the alignment film 24.

[0174] Furthermore, even when the area surrounding the detection point is the lens region 16, when exposing the alignment film 24 as described above, a portion of the area corresponding to the lens region 16 is masked and exposed, and the liquid crystal layer 12 is formed on this alignment film 24, thereby forming an area (detection point) where the liquid crystal compound is not aligned.

[0175] Furthermore, if the area surrounding the detection point is an unoriented region 14, the orientation of the liquid crystal compound at the detection point can be, for example, uniaxially oriented. One method for creating such a detection point is to provide through-holes in the shielding portion of the mask during exposure of the alignment film 24 described above, thereby exposing a portion of the unexposed region of the alignment film 24. Since, for example, a spherical wave is irradiated onto the region exposed through the through-hole, the liquid crystal compound of the liquid crystal layer 12 formed on this region is oriented, and a uniaxially oriented region (detection point) is formed.

[0176] In this case, the distance from the detection point to the center point P0 of the lens region 16 is determined by the distance between the position of the through-hole provided in the shielding portion of the mask and the center position of the interference exposure.

[0177] Furthermore, if the detection point is located on a layer other than the liquid crystal layer 12, such as a resin film 22, the detection point may be formed by methods such as printing, laser processing, or label application.

[0178] Furthermore, if the resin film 22 on which the detection points are provided is a support 22a used when forming the liquid crystal layer 12, for example, two or more detection points may be formed on the support 22a in advance, and after applying the photo-alignment material to the support 22a, when exposing the alignment film 24, the position that will be the center point of the alignment pattern may be aligned to a position defined by the distance between the two or more detection points before exposing the alignment film 24. By forming the liquid crystal layer 12 on the alignment film 24 exposed in this way, a lens region 16 can be formed in which the center point is defined by the distance from the two or more detection points.

[0179] Alternatively, when exposing the alignment film 24, the coordinates of the exposure position within the main surface of the support 22a may be stored, and after exposure of the alignment film 24 or after formation of the liquid crystal layer 12, two or more detection points may be formed based on the coordinates of the exposure position.

[0180] In this case, the distance from the detection point to the center point P0 of the lens region 16 is determined from the coordinates of the center position of the interference exposure and the coordinates of the position where the detection point was formed.

[0181] Furthermore, even if the resin film 22 on which the detection points are provided is a protective film, when the alignment film 24 is exposed, the coordinates of the exposure position within the main surface of the support 22a can be stored, and two or more detection points can be formed on the protective film based on the coordinates of the exposure position before or after the protective film is attached to the liquid crystal layer 12.

[0182] The shape of the detection points may be any shape, such as a cross, a point, a line, a circle, or a square. The detection points may be a collection of points or a grid.

[0183] There are no particular limitations on the size of the detection point, but if it is too small, detection may become difficult. On the other hand, if the detection point is too large, the accuracy of identifying the center point of the lens area may decrease. The size of the detection point is preferably 10 μm to 100 mm in diameter of the circumscribed circle, more preferably 100 μm to 50 mm, and even more preferably 500 μm to 20 mm.

[0184] Furthermore, although the detection point has a certain size, the distance from the detection point can be defined as the distance from a reference point within the detection point. For example, the center position of the detection point can be used as the reference point.

[0185] <Other embodiments of the lens region> In the above example, the lens region 16 of the liquid crystal layer 12 was assumed to act as a lens that focuses or diverges transmitted light, but it is not limited to this. The lens region may be a cholesteric liquid crystal layer in which the liquid crystal compound is cholesterically oriented in the thickness direction, and may be a reflective lens that focuses or diverges reflected light.

[0186] Figure 16 is a conceptual cross-sectional view showing another example of the lens region of the liquid crystal film of the present invention. The plan view of Figure 16, viewed from above, is the same as that of Figure 10.

[0187] As conceptually shown in Figure 16, the lens region 17 has a helical structure in which the liquid crystal compound 30 is spirally stacked in the thickness direction, similar to a cholesteric liquid crystal layer in which a normal cholesteric liquid crystal phase is fixed. The structure is such that multiple spirally spiraling liquid crystal compounds 30 are stacked in layers, with one spiral pitch representing one rotation (360° rotation) of the liquid crystal compound 30.

[0188] The cholesteric liquid crystal layer reflects right-circularly polarized or left-circularly polarized light in a specific wavelength range, while transmitting other light, depending on the length of the helical pitch and the direction of spiral rotation (sense) of the liquid crystal compound. In other words, the cholesteric liquid crystal layer possesses wavelength-selective reflectivity and polarization selectivity.

[0189] Furthermore, since the lens region 17 is oriented such that the liquid crystal compound 30 continuously rotates and changes in the planar direction, it refracts (diffracts) incident circularly polarized light in the direction in which the optical axis is continuously rotating and reflects it. In this case, the direction of diffraction differs depending on the rotation direction of the incident circularly polarized light.

[0190] Therefore, the lens region 17, which is a cholesteric liquid crystal layer, reflects right-circularly polarized or left-circularly polarized light of the selected reflection wavelength and diffracts this reflected light.

[0191] Furthermore, the lens region 17, like the lens region 16 described above, has a liquid crystal alignment pattern in which the direction of the optical axis originating from the liquid crystal compound changes while continuously rotating, and which radiates from the inside outwards in one direction. The configuration of the liquid crystal alignment pattern is as described above.

[0192] Such a lens region 17 acts as a reflective focusing lens that reflects and focuses one type of circularly polarized light, and as a reflective divergent lens that reflects and diverges the other type of circularly polarized light.

[0193] The lens region 17, which has a lensing effect in this way, has an optical center point. The center point of the lens region 17 is also defined by the distance from two or more detection points, and the center point can be identified from the distance information from each detection point to the center point.

[0194] The lens region 17 (liquid crystal layer), which is a cholesteric liquid crystal layer, can be formed using the same liquid crystal composition as the one used to form the lens region 16 (liquid crystal layer 12) described above, except that it contains a chiral agent.

[0195] -- Chiral Agents (Optically Active Compounds) -- Chiral agents have the function of inducing a helical structure in the cholesteric liquid crystal phase. Since different chiral agents induce different helical twist directions or helical pitches, they should be selected according to the purpose.

[0196] There are no particular restrictions on the chiral agent, and known compounds (for example, described in the Liquid Crystal Device Handbook, Chapter 3, Section 4-3, Chiral Agents for TN (twisted nematic) and STN (Super Twisted Nematic), page 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989), isosorbide, and isomannide derivatives can be used.

[0197] Chiral agents generally contain an asymmetric carbon atom, but axially asymmetric compounds or planar asymmetric compounds that do not contain an asymmetric carbon atom can also be used as chiral agents. Examples of axially asymmetric compounds or planar asymmetric compounds include binaphthyl, helicene, paracyclophane, and their derivatives. Chiral agents may have polymerizable groups. If both the chiral agent and the liquid crystal compound have polymerizable groups, a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound can form a polymer having repeating units derived from the polymerizable liquid crystal compound and repeating units derived from the chiral agent. In this embodiment, it is preferable that the polymerizable group of the polymerizable chiral agent is of the same type as the polymerizable group of the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is preferably an unsaturated polymerizable group, an epoxy group, or an azilidinyl group, more preferably an unsaturated polymerizable group, and even more preferably an ethylenically unsaturated polymerizable group.

[0198] Furthermore, the chiral agent may be a liquid crystal compound.

[0199] When the chiral agent has a photoisomerizing group, it is preferable because, after coating and orientation, a pattern of the desired reflected wavelength corresponding to the emission wavelength can be formed by photomask irradiation with active light or the like. Preferred photoisomerizing groups are the isomerization site of a photochromic compound, an azo group, an azoxy group, or a cinnamoyl group. Specific compounds that can be used include those described in Japanese Patent Publication No. 2002-080478, 2002-080851, 2002-179668, 2002-179669, 2002-179670, 2002-179681, 2002-179682, 2002-338575, 2002-338668, 2003-313189, and 2003-313292, etc.

[0200] In the liquid crystal composition, the content of the chiral agent is preferably 0.01 to 200 mol%, and more preferably 1 to 30 mol%, relative to the molar amount of the liquid crystal compound.

[0201] There are no restrictions on the thickness of the lens region 17 (liquid crystal layer), which is a cholesteric liquid crystal layer. It can be set appropriately according to the application of the liquid crystal film, the required light reflectivity of the lens region 17, and the forming material, etc.

[0202] Furthermore, the lens region 17, which is a cholesteric liquid crystal layer, may have a helical pitch that changes in the thickness direction. A cholesteric liquid crystal layer with a helical pitch that changes in the thickness direction can be formed by using a chiral agent that undergoes reverse isomerization, dimerization, and isomerization and dimerization upon irradiation with light, thereby changing the helical twisting power (HTP), and irradiating the liquid crystal composition that forms the cholesteric liquid crystal layer with light of a wavelength that changes the HTP of the chiral agent before curing or during curing of the liquid crystal composition.

[0203] For example, by using a chiral agent whose HTP decreases upon light irradiation, the HTP of the chiral agent decreases upon light irradiation. Here, the irradiated light is absorbed by the forming material of the cholesteric liquid crystal layer (lens region 17). Therefore, for example, when light is irradiated from above, the amount of light irradiation gradually decreases from top to bottom. That is, the amount of decrease in the HTP of the chiral agent gradually decreases from top to bottom. As a result, in the upper part where the HTP has decreased significantly, the induction of helical formation is small, so the helical pitch becomes longer, and in the lower part where the decrease in HTP is small, helical formation is induced by the HTP that the chiral agent inherently possesses, so the helical pitch becomes shorter. This makes it possible to form a cholesteric liquid crystal layer in which the helical pitch changes in the thickness direction.

[0204] Such light irradiation may be performed before exposure for curing of the cholesteric liquid crystal layer (lens region 17), or simultaneously with exposure for curing. Furthermore, the wavelength of light used to change the HTP of the chiral agent and the wavelength of light used to cure the cholesteric liquid crystal layer (lens region 17) may be the same or different.

[0205] [Method for Identifying the Center Point of the Lens Region of a Liquid Crystal Film] The method for identifying the center point of the lens region of a liquid crystal film according to the present invention (hereinafter also referred to as the identification method of the present invention) is a method for identifying the center point of the lens region by distance from the two or more detection points in a liquid crystal film having a lens region having a liquid crystal layer formed using a composition containing a liquid crystal compound, wherein the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane, and the lens region has two or more detectable detection points either inside or outside the lens region.

[0206] In other words, the method for identifying the present invention is a method for identifying the center point of the lens region in the liquid crystal film of the present invention, which has a liquid crystal layer having a lens region and two or more detection points as described above.

[0207] As an example of a method for specifying the present invention, specifically, two or more detection points provided on the liquid crystal film are first detected. As described above, when the detection points are provided on the liquid crystal layer 12, the orientation state of the liquid crystal compound differs between the detection points and the surrounding area, resulting in different light transmittances, so the detection points can be easily detected by visual inspection. Also, when the detection points are provided on the resin film 22, the detection points are formed by printing, laser processing, etc., so the detection points can be easily detected by visual inspection.

[0208] Next, the center point of the lens region is identified based on the distance information from each of the two or more detection points to the center point of the lens region. As shown in the example in Figure 2, if there are two detection points and the center point P0 lies on the line segment L connecting the two detection points 20a and 20b, there is only one intersection point between the curve with radius R1 from detection point 20a and the curve with radius R2 from detection point 20b. Therefore, the center point P0 can be identified by determining the position of this intersection point.

[0209] Furthermore, as shown in the example in Figure 4, if there are two detection points and the center point P0 does not lie on the line segment L connecting the two detection points 20a and 20b, there are two intersection points between the curve with radius R1 from detection point 20a and the curve with radius R2 from detection point 20b. The center point P0 can be identified by determining the position of the intersection point that lies within the lens region 16.

[0210] Furthermore, as shown in the example in Figure 5, if there are three detection points, the center point P0 can be identified by determining the position of the one intersection point where the curve with radius R1 from detection point 20a, the curve with radius R2 from detection point 20b, and the curve with radius R3 from detection point 20c intersect.

[0211] Furthermore, as shown in the example in Figure 1, if the liquid crystal film 10a has multiple lens regions 16 and there are multiple combinations of two or more detection points corresponding to each lens region 16, the center point of each lens region can be identified in the same manner as described above using the two or more detection points corresponding to each lens region 16.

[0212] Furthermore, as shown in the example in Figure 7, if the liquid crystal film 10b has multiple lens regions and one set of two or more detection points, the center point of each lens region can be identified in the same manner as described above using one set of two or more detection points.

[0213] By identifying the center point of the lens region 16 of the liquid crystal layer 12 of the liquid crystal film in this way, the liquid crystal film can be easily and accurately aligned when stacking it with other optical elements.

[0214] There are no restrictions on the optical elements that can be combined with the liquid crystal film; various known elements can be used. Examples of optical elements that can be combined with liquid crystal films include other lenses, polarizers, phase difference plates, microlens arrays, apertures, anti-reflective films, light-diffusing films, prisms, isolators, and the like.

[0215] Furthermore, when cutting a liquid crystal film having multiple lens regions 16, as shown in the example in Figure 1 or Figure 7, for example, by identifying the center point of each lens region 16, the liquid crystal film can be easily and accurately cut into a shape with the lens regions 16 in the desired positions, using the center point of each lens region 16 as a reference point.

[0216] Although the liquid crystal film of the present invention and the method for identifying the center point of the lens region of the liquid crystal film have been described in detail above, the present invention is not limited to the examples described above, and various improvements and modifications may be made without departing from the spirit of the present invention.

[0217] The features of the present invention will be further described in detail below with reference to examples. The materials, reagents, amounts used, amounts of substance, ratios, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.

[0218] [Example 1] <Formation of alignment film> A glass substrate measuring 150 mm x 150 mm and 0.5 mm thick was used as a support, and the following alignment film forming coating solution was applied by spin coating. The support coated with this alignment film forming coating solution was dried on a hot plate at 60°C for 60 seconds to form an alignment film.

[0219] Coating solution for forming alignment film ---------------------------------------------------------------- Photo-alignment material A 1.00 parts by mass Water 16.00 parts by mass Butoxyethanol 42.00 parts by mass Propylene glycol monomethyl ether 42.00 parts by mass ----------------------------------------------------------------

[0220] Photo alignment material A

[0221] <Exposure of the alignment film> An alignment film P-1 was formed by exposing the alignment film using an exposure apparatus as shown in Figure 15, thereby forming an alignment film P-1 having an alignment pattern that allows for the formation of a liquid crystal alignment pattern, as shown in Figure 10, in which the optical axis of the liquid crystal compound changes radially in one direction while continuously rotating.

[0222] In this process, a mask with a 30 mm × 30 mm opening was placed between the λ / 4 plate and the alignment film to define the region to be exposed by interference. Furthermore, a coordinate system on the main surface of the alignment film 24 (support) was defined with the lower left corner of the opening of the mask as the origin, and φ5 mm dot-shaped masking was performed at the positions of coordinate A (0 mm, 0 mm) and coordinate B (30 mm, 30 mm).

[0223] Furthermore, in the in-plane direction, the mask was positioned so that the coordinates O (15 mm, 15 mm) of the center of the mask's opening were aligned with the center position of the interference exposure.

[0224] Therefore, the distance between the center point of the lens area and each of the two detection points is 21.21 mm.

[0225] The period Λ of the orientation pattern of the orientation film varies within the plane, but its minimum value was set to 1 μm. The period Λ of the orientation pattern was adjusted to match the focal length of the lens used for integration into the head-mounted display during evaluation.

[0226] The light source used was a laser emitting light with a wavelength of 355 nm. The exposure dose due to interference was 1000 mJ / cm². 2 That's what I decided.

[0227] (Formation of the liquid crystal layer) The following liquid crystal composition A-1 was prepared as a liquid crystal composition for forming a liquid crystal layer that includes a region to be the lens region.

[0228] Liquid crystal composition A-1 -------------------------------------------------- Liquid crystal compound L-1 100.00 parts by mass Polymerization initiator (BASF, Irgacure OXE01) 1.00 parts by mass Leveling agent T-1 0.08 parts by mass Methyl ethyl ketone 1050.00 parts by mass --------------------------------------------------

[0229] Liquid crystal compound L-1

[0230] Leveling agent T-1

[0231] The above liquid crystal composition A-1 was applied to the alignment film P-1, and the coating was heated to 80°C on a hot plate. Then, under a nitrogen atmosphere, ultraviolet light with a wavelength of 365 nm was applied at a rate of 300 mJ / cm using a high-pressure mercury lamp. 2 By irradiating the coating with a specific irradiation dose, the orientation of the liquid crystal compound was fixed. This resulted in the fabrication of a liquid crystal film having a lens region with a radial liquid crystal orientation pattern, a non-coherent exposure region around the lens region, and a liquid crystal layer with two detection points.

[0232] [Example 2] A liquid crystal film was prepared in the same manner as in Example 1, except that when the alignment film was exposed, φ5 mm dots were masked at positions A (0 mm, 0 mm), C (0 mm, 30 mm), and B (30 mm, 30 mm). The liquid crystal film of Example 2 has a lens region having a radial liquid crystal alignment pattern and a liquid crystal layer having three detection points.

[0233] The distance between the center point of the lens area and each of the three detection points is 21.21 mm.

[0234] [Example 3] A liquid crystal film was prepared in the same manner as in Example 1, except that when the alignment film was exposed, masking was performed in the form of φ5 mm dots at coordinates D (5 mm, 10 mm) and coordinates E (15 mm, 25 mm). The liquid crystal film of Example 3 has a lens region having a radial liquid crystal alignment pattern and a liquid crystal layer having two detection points.

[0235] The distance between the detection point at coordinate D and the center point of the lens area is 11.18 mm, and the distance between the detection point at coordinate E and the center point of the lens area is 10.0 mm.

[0236] [Example 4] Before forming the alignment film, two φ5 mm dot-shaped marks (detection points) were formed on the support using a laser marker. The two marks were formed at positions 30 mm apart in the vertical direction and 30 mm apart in the horizontal direction.

[0237] Next, the orientation film was coated onto the support and dried in the same manner as in Example 1.

[0238] Next, the alignment film was exposed in the same manner as in Example 1. At that time, the mask was positioned so that the coordinates O (15 mm, 15 mm) of the center of the mask's opening were aligned with the center of interference exposure in the in-plane direction, and the support was positioned so that the positions of the two marks formed on the support were aligned with coordinates A (0 mm, 0 mm) and B (30 mm, 30 mm), respectively.

[0239] Next, a liquid crystal layer was formed in the same manner as in Example 1 to produce a liquid crystal film. The liquid crystal film of Example 4 has a liquid crystal layer having a lens region with a radial liquid crystal alignment pattern and a support (resin film) having two detection points.

[0240] The distance between the center point of the lens area and each of the two detection points is 21.21 mm.

[0241] [Example 5] A liquid crystal film was manufactured in the same manner as in Example 4, except that two marks to be formed on the support were formed at positions 45 mm apart vertically and 45 mm apart horizontally, and the support was set up so that the positions of the two marks were aligned to coordinates F (15 mm, 60 mm) and G (60 mm, 15 mm), respectively, when the alignment film was exposed. The liquid crystal film of Example 5 has a liquid crystal layer having a lens region having a radial liquid crystal alignment pattern and a support (resin film) having two detection points.

[0242] The distance between the center point of the lens area and each of the two detection points is 45 mm.

[0243] [Comparative Example 1] A liquid crystal film was manufactured in the same manner as in Example 1, except that the exposure of the alignment film was performed without masking the area that would become the detection point, and no detection points were provided.

[0244] [Evaluation] The lenses were removed from a head-mounted display (HMD: HTC VIVE VR head-mounted display manufactured by HTC Corporation), and the liquid crystal films prepared in the example and comparative example were installed in the lens positions, respectively. In the case of the liquid crystal film of the example, detection points were detected by visual inspection, the center point of the lens area was identified from the detection points, and the film was installed so that the center point of the lens area was aligned with the predetermined position in the design. In the case of the liquid crystal film of the comparative example, the center point was directly identified by visual inspection, and the film was installed so that the center point of the lens area was aligned with the predetermined position in the design.

[0245] The HMDs incorporating the liquid crystal films prepared in the examples and comparative examples were fitted, and the images were visually confirmed to be displayed and formed correctly.

[0246] As a result, images could be viewed without any problems in the HMDs incorporating the liquid crystal films of Examples 1 to 5. On the other hand, in the HMD incorporating the liquid crystal film of Comparative Example 1, the center point of the lens area was misaligned, so the image did not form properly and appeared blurry.

[0247] The effects of the present invention are clear from the above.

[0248] 10a-10d Liquid crystal film 12 Liquid crystal layer 14 Unaligned region 16, 16a-16i, 17 Lens region 16A Optical anisotropy layer 18 Non-coherent exposure region 20a-20e Detection point (mark) 22 Resin film 22a Support 24 Alignment film 30 Liquid crystal compound 30A Optical axis 80 Exposure apparatus 82 Laser 84 Light source 86, 94 Polarizing beam splitter 90A, 90B Mirror 92 Lens 96 λ / 4 plate A, A1-A4 Arrow R Region Λ 1 period M Laser light MP P polarization MS S polarization L1, L4 Incident light L2, L5 Transmitted light

Claims

1. A liquid crystal film having a liquid crystal layer formed using a composition containing a liquid crystal compound, wherein the liquid crystal layer has a lens region having a liquid crystal orientation pattern radially from the inside to the outside, in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane, and the lens region has two or more detectable detection points either within or outside the lens region, and the center point of the lens region is defined by the distance from the two or more detection points.

2. The liquid crystal film according to claim 1, wherein the detection point is located outside the lens region of the liquid crystal layer.

3. The liquid crystal film according to claim 1, wherein the liquid crystal layer has a plurality of lens regions.

4. The liquid crystal film according to claim 3, wherein each of the multiple lens regions has multiple combinations of the two or more detection points.

5. The liquid crystal film according to claim 1, wherein the film has two detection points, and the two detection points and the center point of the lens region lie on a single straight line.

6. The liquid crystal film according to claim 5, wherein the center point of the lens region is located between the two detection points.

7. The liquid crystal film according to claim 1, wherein the detection point is provided in the liquid crystal layer, and the orientation state of the liquid crystal compound at the detection point is different from the orientation state of the liquid crystal compound in the region surrounding the detection point.

8. The liquid crystal film according to claim 1, wherein the liquid crystal film further comprises a resin film, and the detection point is provided on the resin film.

9. A liquid crystal film having a lens region having a liquid crystal orientation pattern radially from the inside to the outside, formed using a composition containing a liquid crystal compound, wherein the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating in one direction within the plane, and two or more detectable detection points either within or outside the lens region, wherein the center point of the lens region is determined by the distance from the two or more detection points.

Images