Optical element and optical element

Abstract

An optical element according to the present invention has, in order, a first lambda / 4 sheet, an optical laminate having two or more liquid crystal layer groups in the thickness direction, and a second lambda / 4 sheet. The liquid crystal layer group is composed of a first liquid crystal layer in which a liquid crystal compound that is twisted in the thickness direction is fixed, and a second liquid crystal layer in which a liquid crystal compound that is twisted in the thickness direction is fixed, the twisting direction of the liquid crystal compound being opposite to the twisting direction of the liquid crystal compound in the first liquid crystal layer. In the liquid crystal layer group, the orientation direction of the liquid crystal compound on the second liquid crystal layer-side surface of the first liquid crystal layer is parallel to the orientation direction of the liquid crystal compound on the first liquid crystal layer-side surface of the second liquid crystal layer. The twist angle of the liquid crystal compound in the first liquid crystal layer is equal to the twist angle of the liquid crystal compound in the second liquid crystal layer.

Description

Technical Field

[0001] This invention relates to an optical element and an optical component made using the optical element. Background Technology

[0002] In recent years, AR (Augmented Reality) glasses have been used to overlay and display virtual images and various information on real-world viewing scenarios. AR glasses are also known as smart glasses, head-mounted displays (HMDs), and AR glasses.

[0003] Patent document 1 discloses an optical element with low wavelength dependence of refraction angle, for example, capable of refracting red light, green light and blue light incident from the same direction into almost the same direction, and describes that the optical element can be used in AR glasses.

[0004] In the optical element described in Patent Document 1, by combining a wavelength-selective retardation layer (optical element) and multiple optical anisotropic layers, the wavelength dependence of the refraction angle can be reduced. Patent Document 1 also describes that the aforementioned wavelength-selective retardation layer (optical element) has the function of converting circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction.

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2019 / 131918 Summary of the Invention

[0008] The technical problem to be solved by the invention

[0009] The aforementioned patent documents describe a wavelength-selective phase difference layer (optical element) as described above, but it is desirable to provide an optical element with a novel structure that differs from that structure.

[0010] Therefore, the objective of this invention is to provide an optical element with a novel structure that can convert only circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction.

[0011] Furthermore, the objective of this invention is to provide an optical element using the aforementioned optical components.

[0012] means for solving technical problems

[0013] The present invention is the result of in-depth research conducted by the inventors to solve the aforementioned problems. Specifically, it was discovered that the above-mentioned problems can be solved according to the following structure.

[0014] [1] An optical element comprising, in sequence, a first λ / 4 sheet, an optical laminate, and a second λ / 4 sheet, wherein,

[0015] The aforementioned optical laminate has two or more liquid crystal layer groups in the thickness direction. Each liquid crystal layer group consists of a first liquid crystal layer formed by fixing a liquid crystal compound that is twisted and oriented in the thickness direction, and a second liquid crystal layer formed by fixing a liquid crystal compound that is twisted and oriented in the thickness direction, wherein the twisting direction of the liquid crystal compound is opposite to the twisting direction of the liquid crystal compound in the first liquid crystal layer.

[0016] In the aforementioned liquid crystal layer group, the orientation direction of the liquid crystal compound on the surface of the first liquid crystal layer on the side of the second liquid crystal layer is parallel to the orientation direction of the liquid crystal compound on the surface of the second liquid crystal layer on the side of the first liquid crystal layer.

[0017] The twist angle of the liquid crystal compound in the first liquid crystal layer is equal to the twist angle of the liquid crystal compound in the second liquid crystal layer.

[0018] [2] According to the optical elements described in [1], wherein,

[0019] Either a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound is included in the liquid crystal compound in the first liquid crystal layer, and the other is included in the liquid crystal compound in the second liquid crystal layer.

[0020] [3] According to the optical elements described in [1] or [2], wherein,

[0021] At least one of the aforementioned first λ / 4 sheet and the aforementioned second λ / 4 sheet is a laminate consisting of a liquid crystal layer A formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction and a liquid crystal layer B formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction.

[0022] [4] According to the optical elements described in [3], wherein,

[0023] The twist angle of the liquid crystal compound in the aforementioned liquid crystal layer A is 16.5–36.5°, and the refractive index difference Δn of the aforementioned liquid crystal layer A is... A The thickness d of the aforementioned liquid crystal layer A A The product Δn A d A The wavelength range is 252–312 nm.

[0024] The twist angle of the liquid crystal compound in the aforementioned liquid crystal layer B is 68.6–88.6°, and the refractive index difference Δn of the aforementioned liquid crystal layer B is... B The thickness d of the liquid crystal layer B mentioned above B The product Δn B d BThe wavelength range is 110–170 nm.

[0025] [5] According to the optical elements described in [3] or [4], wherein,

[0026] The aforementioned liquid crystal layer A is disposed on the optical laminate side.

[0027] The orientation direction of the liquid crystal compound on the side surface of the liquid crystal layer A of the optical laminate is parallel to the orientation direction of the liquid crystal compound on the side surface of the optical laminate of the liquid crystal layer A.

[0028] [6] The optical element according to any one of [3] to [5], wherein,

[0029] The orientation direction of the liquid crystal compound on the liquid crystal layer B side surface of the liquid crystal layer A is parallel to the orientation direction of the liquid crystal compound on the liquid crystal layer A side surface of the liquid crystal layer B.

[0030] [7] An optical element having:

[0031] Multiple optically anisotropic layers are formed using a composition comprising a liquid crystal compound and have a liquid crystal alignment pattern that changes while the orientation of the optical axis originating from the liquid crystal compound continuously rotates in at least one in-plane direction; and

[0032] The optical element as described in any one of [1] to [6] is disposed between at least one pair of two adjacent optical anisotropic layers in the plurality of optical anisotropic layers, and,

[0033] In the liquid crystal alignment pattern of the optical anisotropy layer, when the length of the 180° rotation of the optical axis of the liquid crystal compound in one direction, in which the orientation of the optical axis originating from the liquid crystal compound changes while rotating continuously, is defined as one cycle, the length of one cycle of at least one optical anisotropy layer is different from that of the other optical anisotropy layers.

[0034] Invention Effects

[0035] According to the present invention, the objective is to provide an optical element with a novel structure that can convert only circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction.

[0036] Furthermore, according to the present invention, it is also possible to provide an optical element using the above-described optical components. Attached Figure Description

[0037] Figure 1 This is a diagram that conceptually illustrates an example of the optical elements of the present invention.

[0038] Figure 2 These are diagrams used to illustrate the optical elements of the present invention.

[0039] Figure 3 These are diagrams used to illustrate the optical elements of the present invention.

[0040] Figure 4 This is a diagram that conceptually illustrates another example of the optical elements of the present invention.

[0041] Figure 5 It is used for explanation Figure 4 A diagram showing the optical components.

[0042] Figure 6 This is a diagram that conceptually illustrates an example of the optical element of the present invention.

[0043] Figure 7 It is a conceptual representation Figure 6 A diagram of the optical anisotropy layer of the optical element shown.

[0044] Figure 8 yes Figure 6 A top view of the optical anisotropy layer of the optical element shown.

[0045] Figure 9 It means Figure 6 A conceptual diagram illustrating the function of the optical anisotropy layer in the optical element shown.

[0046] Figure 10 It means Figure 6 A conceptual diagram illustrating the function of the optical anisotropy layer in the optical element shown.

[0047] Figure 11 It means Figure 6 A conceptual diagram illustrating the function of the optical element shown.

[0048] Figure 12 It means Figure 6 A conceptual diagram illustrating the function of the optical element shown.

[0049] Figure 13 This is a diagram that conceptually illustrates another example of the optical element of the present invention.

[0050] Figure 14 It means Figure 12 A conceptual diagram illustrating the function of the optical element shown.

[0051] Figure 15 It means Figure 12 A conceptual diagram illustrating the function of the optical element shown.

[0052] Figure 16 It is a conceptual representation of the concept of Figure 6A diagram of an example of an exposure apparatus for exposing the alignment film of an optical element.

[0053] Figure 17 This is a top view of another example of the optical anisotropy layer of the optical element of the present invention.

[0054] Figure 18 It is a conceptual representation of the formation Figure 16 A diagram showing an example of an exposure apparatus for exposing an alignment film of an optically anisotropic layer.

[0055] Figure 19 This is a diagram illustrating, conceptually, an example of an AR glasses using the optical elements of the present invention.

[0056] Figure 20 This is a diagram that conceptually illustrates another example of the optical anisotropy layer of the optical element of the present invention. Detailed Implementation

[0057] The present invention will now be described in detail.

[0058] The description of the constituent elements described below is sometimes based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0059] The following explains the meaning of each statement in this specification.

[0060] In this specification, the numerical range indicated by “~” represents the range included by the values ​​recorded before and after “~” as the lower and upper limits.

[0061] Re(λ) and Rth(λ) represent the in-plane delay and thickness direction delay at wavelength λ, respectively. Re(λ), Rth(λ), and Δnd are measured using an AXOSCAN (manufactured by AXOMETRICS).

[0062] In addition, in this specification, "visible light" refers to 380nm to 780nm. Furthermore, unless otherwise specified, the measurement wavelength in this specification is 550nm.

[0063] Furthermore, in this specification, the relationships of angles (e.g., "orthogonal," "parallel," and specific angles) include the range of errors permissible in the technical field to which this invention pertains. Specifically, this refers to a range of strictly defined angles ± less than 10°, and the error between this range and the strictly defined angle is preferably 5° or less, more preferably 3° or less.

[0064] Furthermore, the figures shown below are conceptual diagrams used to illustrate the present invention, and the positional relationships, sizes, thicknesses, and shapes of the constituent elements may sometimes differ from the actual situation.

[0065] <Optical Components>

[0066] The optical components of the present invention sequentially include a first λ / 4 sheet, an optical laminate, and a second λ / 4 sheet.

[0067] The aforementioned optical laminate has two or more liquid crystal layer groups in the thickness direction. Each liquid crystal layer group consists of a first liquid crystal layer formed by fixing a liquid crystal compound that is twisted and oriented in the thickness direction, and a second liquid crystal layer formed by fixing a liquid crystal compound that is twisted and oriented in the thickness direction, wherein the twisting direction of the liquid crystal compound is opposite to the twisting direction of the liquid crystal compound in the first liquid crystal layer.

[0068] Furthermore, in the aforementioned liquid crystal layer group, the orientation direction of the liquid crystal compound on the surface of the first liquid crystal layer on the second liquid crystal layer side is parallel to the orientation direction of the liquid crystal compound on the surface of the second liquid crystal layer on the first liquid crystal layer side. Also, the twist angle of the liquid crystal compound in the first liquid crystal layer is equal to the twist angle of the liquid crystal compound in the second liquid crystal layer.

[0069] Figure 1 The image below conceptually illustrates an example of the optical elements of the present invention.

[0070] Figure 1 The optical element 210 shown includes a first λ / 4 sheet 212, a second λ / 4 sheet 214, and a liquid crystal polarizing interference element 216. The liquid crystal polarizing interference element 216 is disposed between the first λ / 4 sheet 212 and the second λ / 4 sheet 214. The liquid crystal polarizing interference element 216 corresponds to the optical stack in the optical element of the present invention.

[0071] The liquid crystal polarizing interference element 216 is an optical element that acts as a λ / 2 phase retardation plate for light in a specific wavelength region (specific wavelength) but does not act as a phase retardation layer for light in other wavelength regions. Therefore, Figure 1 The optical element 210 shown can convert circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction. Circularly polarized light outside the aforementioned specific wavelength region is transmitted without changing its rotation direction. That is, the optical element 210 of the present invention functions as a wavelength-selective phase difference layer for circularly polarized light.

[0072] The first λ / 4 sheet 212 and the second λ / 4 sheet 214 are sheets that have the function of converting linearly polarized light of a specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). More specifically, they are sheets that display an in-plane delay of λ / 4 (or an odd multiple thereof) at a specified wavelength λnm.

[0073] Regarding the first λ / 4 piece 212 and the second λ / 4 piece 214, there are no particular restrictions, and known λ / 4 pieces can be used. The first λ / 4 piece 212 and the second λ / 4 piece 214 will be described in detail later.

[0074] In the optical element 210 of the example figure, a liquid crystal polarizing interference element 216 is arranged between the first λ / 4 piece 212 and the second λ / 4 piece 214.

[0075] In addition, Figure 1 In the middle, the first λ / 4 piece 212 and the second λ / 4 piece 214 are separated from the liquid crystal polarizing interference element 216.

[0076] However, the present invention is not limited thereto. The first λ / 4 sheet 212 and the second λ / 4 sheet 214 can be in contact with the liquid crystal polarizing interference element 216 and stacked thereon. Furthermore, when the first λ / 4 sheet 212 and the second λ / 4 sheet 214 are in contact with the liquid crystal polarizing interference element 216, they can be bonded together as needed using an adhesive that is transparent to transmitted light, such as OCA (Optical Clear Adhesive) or acrylic adhesive.

[0077] The liquid crystal polarization interference element 216 is an element formed by stacking an even number of liquid crystal layers, which are formed by fixing a liquid crystal compound 218 that is twisted and oriented along the thickness direction. The liquid crystal compound 218 is a rod-shaped liquid crystal compound.

[0078] Specifically, the liquid crystal polarization interference element 216 is an element formed by alternately stacking a first liquid crystal layer 220 and a second liquid crystal layer 224. The first liquid crystal layer 220 is a layer formed by fixing a liquid crystal compound 218 that is twisted and oriented along the thickness direction. The second liquid crystal layer 224 is a layer formed by fixing a liquid crystal compound 218 that is twisted and oriented along the thickness direction, and the twisting directions of the first liquid crystal layer 220 and the liquid crystal compound 218 are opposite.

[0079] The combination of the liquid crystal polarization interference element 216, a first liquid crystal layer 220 and a second liquid crystal layer 224 is set as a liquid crystal layer group 226, and has a structure in which two or more liquid crystal layer groups 226 are stacked in the thickness direction.

[0080] Therefore, the total number of stacked layers of the first liquid crystal layer 220 and the second liquid crystal layer 224 is an even number.

[0081] In a liquid crystal layer group 226, the orientation direction of the liquid crystal compound 218 on the surface of the first liquid crystal layer 220 on the side of the second liquid crystal layer 224 is parallel to the orientation direction of the liquid crystal compound 218 on the surface of the second liquid crystal layer 224 on the side of the first liquid crystal layer 220.

[0082] That is, in a liquid crystal layer group 226, the orientation direction of the liquid crystal compound 218 is parallel at the interface between the first liquid crystal layer 220 and the second liquid crystal layer 224.

[0083] In a liquid crystal layer group 226, the orientation direction of the liquid crystal compound 218 on the surface of the first liquid crystal layer 220 on the side of the second liquid crystal layer 224 and the orientation direction of the liquid crystal compound 218 on the surface of the second liquid crystal layer 224 on the side of the first liquid crystal layer 220 can be detected by cutting the liquid crystal polarization interference element 216 in an inclined direction and analyzing the orientation direction of the liquid crystal on the surface of its cross section.

[0084] This method is described in detail in Yohei Takahashi et al.'s "Depth-Dependent Determination of Molecular Orientation for WV-Film" (FMC8-3, IDW'04, 651-654).

[0085] Furthermore, in one liquid crystal layer group 226, the twist angle in the thickness direction of the liquid crystal compound 218 in the first liquid crystal layer 220 is equal to the twist angle in the thickness direction of the liquid crystal compound 218 in the second liquid crystal layer 224.

[0086] As described above, the liquid crystal compounds 218 of the first liquid crystal layer 220 and the second liquid crystal layer 224 are twisted in opposite directions in the thickness direction. That is, for example, when the twist angle of the liquid crystal compound 218 in the first liquid crystal layer 220 is "φ [°]", the twist angle of the liquid crystal compound 218 in the first liquid crystal layer 220 becomes "-φ [°]".

[0087] Therefore, in one liquid crystal layer group 226, the liquid crystal compound 218 is twisted in the thickness direction, twisted to a certain angle in the first liquid crystal layer 220, and then twisted back to its original position in the second liquid crystal layer 224. For example, if the twist angle of the liquid crystal compound 218 in the thickness direction is 30°, the liquid crystal compound 218 is twisted from 0° to 30° in the first liquid crystal layer 220, and then twisted back from 30° to 0° in the second liquid crystal layer 224.

[0088] In addition, in this example, as an example, in the twist angle (torsion angle) of the liquid crystal compound, the direction of the transmission axis of the 1λ / 4th piece 212 is set to 0°, the clockwise direction is set to positive (+), and the counterclockwise direction is set to negative (-).

[0089] That is, the absolute values ​​of the twist angles of the first liquid crystal layer 220 and the second liquid crystal layer 224 are equal.

[0090] As described above, in the liquid crystal polarization interference element 216, the liquid crystal compound 218 (rod-shaped liquid crystal compound) is twisted and oriented in the thickness direction, and the orientation of the liquid crystal compound 218 at the interface is parallel. The first liquid crystal layer 220 and the second liquid crystal layer 224, whose twisting directions are opposite and whose absolute values ​​of twisting angles are equal, are stacked alternately in the thickness direction.

[0091] That is, the light passing through the liquid crystal polarization interference element 216 is alternately and repeatedly affected by a slow axis that rotates only a predetermined angle in one direction and a slow axis that rotates only a predetermined angle in the opposite direction. As an example, when the absolute value of the twist angle of the liquid crystal compound 218 is 30°, the light passing through the liquid crystal polarization interference element 216 is alternately and repeatedly affected by a slow axis that rotates from 0° to 30° and by a slow axis that rotates from 30° to 0°.

[0092] Therefore, in the liquid crystal polarization interference element 216, the wavelength region for converting circularly polarized light into circularly polarized light with the opposite rotation direction is determined according to the optical element 210. The Δnd of the first liquid crystal layer 220 and the second liquid crystal layer 224 is set. Furthermore, the twist angle of the liquid crystal compound in the first liquid crystal layer 220 and the second liquid crystal layer 224 is adjusted according to the total number of layers of the first liquid crystal layer 220 and the second liquid crystal layer 224. As a result, a liquid crystal polarization interference element 216 can be formed that acts as a λ / 2 phase retardation plate for light in a specific wavelength region but does not act as a phase retardation plate for light other than that, i.e., no delay is felt.

[0093] The liquid crystal polarizing interference element 216 has several groups of liquid crystal layers 226, and the orientation direction of the liquid crystal on the surface of its cross-section can be detected by cutting the liquid crystal polarizing interference element 216 along an inclined direction and analyzing it. Various methods are described in detail in the aforementioned literature by Yohei Takahashi et al.

[0094] Furthermore, the change in the twisting direction of the liquid crystal is based on the difference in chiral reagents, and can be determined by using a TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) device (manufactured by ION-TOF Corporation, TOF.SIMS5) and other methods, based on the difference in composition in the depth direction of the element.

[0095] In Δnd of the first liquid crystal layer 220 and the second liquid crystal layer 224 constituting the liquid crystal polarization interference element 216, Δn is the birefringence of the liquid crystal compound 218 constituting the first liquid crystal layer 220 and the second liquid crystal layer 224. Furthermore, d is the thickness of the first liquid crystal layer 220 and the second liquid crystal layer 224. Additionally, Δn can also be measured using an AxoScan or similar device manufactured by AxoMetrix.

[0096] In this invention, the Δnd values ​​of the first liquid crystal layer 220 and the second liquid crystal layer 224 are equal.

[0097] As described above, the liquid crystal polarization interference element 216 only acts as a λ / 2 phase retardation plate for light in a specific wavelength region. Correspondingly, the Δnd of the first liquid crystal layer 220 and the second liquid crystal layer 224 is set to the wavelength at which the liquid crystal polarization interference element 216 is assumed to function as a λ / 2 phase retardation plate, that is, half the center wavelength (half wavelength) of the wavelength region at which the optical element 210 is assumed to convert circularly polarized light into circularly polarized light with the opposite rotation direction.

[0098] For example, if the center wavelength of the wavelength region in which the liquid crystal polarization interference element 216 acts as a λ / 2 phase difference plate, i.e., the wavelength region in which the optical element 210 converts circularly polarized light into circularly polarized light with the opposite rotation direction, is assumed to be 550 nm, then the Δnd of the first liquid crystal layer 220 and the second liquid crystal layer 224 is 275 nm.

[0099] In addition, the Δnd of the first liquid crystal layer 220 and the second liquid crystal layer 224 may have an error of about ±10% relative to half of the center wavelength of the wavelength region in which the optical element 210 converts circularly polarized light into circularly polarized light with the opposite rotation direction.

[0100] On the other hand, regarding the twist angle of the liquid crystal compound 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224 constituting the liquid crystal polarization interference element 216, based on the center wavelength of the wavelength region where the optical element 210 converts circularly polarized light into circularly polarized light with the opposite rotation direction and the total number of layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224, the optimal twist angle of the liquid crystal polarization interference element 216 as a λ / 2 phase difference plate is set by simulation.

[0101] In this simulation, conventional optical simulation mechanisms can be used, in addition to LCD Master1D (manufactured by SHINTECH Co., Ltd., Ver9.8.0.0) for calculation.

[0102] Here, according to the inventor's simulation, the twist angle φ of the liquid crystal compound 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224 with respect to the total number of layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224 is as follows:

[0103] When the number of layers N is 2 (1 group of liquid crystal layers), the appropriate value of the twist angle φ is 63.6°;

[0104] When the number of layers N is 4 (2 groups of liquid crystal layers), the appropriate value of the twist angle φ is 35.5°;

[0105] With a layer count N of 6 (3 liquid crystal layers), the optimal twist angle φ is 23.6°.

[0106] When the number of layers N is 8 (4 groups of liquid crystal layers), the appropriate value of the twist angle φ is 17.7°;

[0107] When the number of layers N is 10 (5 groups of liquid crystal layers), the appropriate value of the twist angle φ is 14.1°;

[0108] When the number of layers N is 12 (6 groups of liquid crystal layers), the appropriate value of the twist angle φ is 11.8°;

[0109] When the number of layers N is 14 (7 groups of liquid crystal layers), the appropriate value of the twist angle φ is 10.1°;

[0110] With a layer count N of 16 (8 liquid crystal layers), the optimal twist angle φ is 8.8°.

[0111] like Figure 2 As conceptually illustrated, if this result (solid line) is fitted with an approximate curve (dashed line), the following formula is preferably used with φ = 129.05 × N. -0.961 Consistent.

[0112] Accordingly, in this invention, the twist angle ±φ[°] of the liquid crystal compound 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224, corresponding to the total number of stacked layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224, is preferably set as follows:

[0113] 0.9×(129.05×N -0.961 )≤|φ|≤1.1×(129.05×N -0.961 ),

[0114] A more preferred setting is:

[0115] |φ|=129.05×N -0.961 .

[0116] Furthermore, the absolute values ​​of the twist angles of the liquid crystal compounds 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224 are not limited to a uniform manner, but may also have an error of less than ±10% of the absolute value of the twist angle.

[0117] Preferably, the error is small, and the absolute values ​​of the twist angles of the liquid crystal compounds 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224 are most preferably the same.

[0118] The twist angle of the liquid crystal compound 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224 constituting the liquid crystal polarization interference element 216 can be detected by cutting the liquid crystal polarization interference element 216 along an inclined direction and analyzing the orientation direction of the liquid crystal on the surface of its cross-section. Each of these methods is described in detail in the aforementioned literature by Yohei Takahashi et al.

[0119] Furthermore, the torsion angle of the liquid crystal compound 218 can also be measured using an AxoScan (manufactured by Axometrics) through a separation measurement mechanism based on a model with assumed input parameters.

[0120] There is no limitation on the thickness d of the first liquid crystal layer 220 and the second liquid crystal layer 224. Depending on the liquid crystal compound 218 used, the Δnd of the optical element 210 is appropriately set so that its thickness reaches half the wavelength of the center wavelength of the wavelength region that converts circularly polarized light into circularly polarized light with the opposite rotation direction.

[0121] The thickness d of the first liquid crystal layer 220 and the second liquid crystal layer 224 is preferably 1 to 5 μm, and more preferably 1 to 3 μm.

[0122] Furthermore, the same liquid crystal compound 218 is typically used to form the first liquid crystal layer 220 and the second liquid crystal layer 224. Also, the Δnd values ​​of the first liquid crystal layer 220 and the second liquid crystal layer 224 are equal. Therefore, the thicknesses of the first liquid crystal layer 220 and the second liquid crystal layer 224 are equal.

[0123] Regarding the total number of stacked layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224, there are no restrictions as long as there are 2 or more groups of liquid crystal layers 226, i.e., 4 or more layers, and the number is even.

[0124] The total number of layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224 is preferably 4 to 30 layers, more preferably 4 to 20 layers, and even more preferably 4 to 10 layers.

[0125] Furthermore, in the optical element 210 of the present invention, the greater the total number of stacked layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224, that is, the greater the number of liquid crystal layer groups 226, the narrower the wavelength region in which the liquid crystal polarization interference element 216 functions as a λ / 2 phase difference layer becomes.

[0126] Therefore, in the optical element 210 of the present invention, the greater the total number N of the first liquid crystal layer 220 and the second liquid crystal layer 224, the narrower the half-peak width (FWHM) of the wavelength region that converts circularly polarized light into circularly polarized light with the opposite rotation direction. In other words, the greater the total number N of the first liquid crystal layer 220 and the second liquid crystal layer 224, the more likely the optical element 210 can be configured as an optical element with a narrow wavelength region that converts circularly polarized light into circularly polarized light with the opposite rotation direction.

[0127] Therefore, the total number of stacked layers N of the first liquid crystal layer 220 and the second liquid crystal layer 224, i.e. the number of liquid crystal layer groups 226, is determined according to the width of the wavelength region required by the optical element 210. In the case of a wide bandwidth, a smaller number of layers is selected, and in the case of a narrow bandwidth, a larger number of layers is appropriately selected.

[0128] This liquid crystal polarizing interference element 216 can be fabricated using known methods.

[0129] As an example, a method can be described using a coating method to form the first liquid crystal layer 220 and the second liquid crystal layer 224.

[0130] First, an orientation film oriented in one direction is formed on a suitably selected support.

[0131] Regarding alignment films, known alignment films include friction-treated films composed of organic compounds such as polymers, tilted vapor-deposited films of inorganic compounds, films with microgrooves, films formed by accumulating LB (Langmuir-Blodgett) films based on the Langmuir-Blodgett process using organic compounds such as ω-trisanoic acid, dioctadecylmethylammonium chloride, and methyl stearate, and films formed by coating a coating solution containing a photo-alignment material onto the surface of a support, drying it, and exposing the coating film to a polarizer such as a wire grid polarizer.

[0132] On the other hand, a composition (liquid crystal composition) for forming a first liquid crystal layer 220 and a composition for forming a second liquid crystal layer 224 are prepared, the compositions comprising a liquid crystal compound and a chiral agent having the function of inducing the liquid crystal compound to twist and align in the thickness direction.

[0133] The twisting directions of the liquid crystal compound 218 in the thickness direction of the first liquid crystal layer 220 and the second liquid crystal layer 224 are opposite, but the twisting direction of the liquid crystal compound in the thickness direction can be selected by choosing a chiral reagent. Furthermore, the twisting angle of the liquid crystal compound 218 in the thickness direction can be adjusted by adjusting the amount of chiral reagent added.

[0134] Furthermore, there are no limitations on the solvent used to prepare the composition; it can be appropriately selected according to the purpose, but organic solvents are preferred. Examples of organic solvents include ketones, haloalkanes, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. One or more of these can be used individually or simultaneously. Among these, ketones are preferred, taking into account the environmental impact.

[0135] The composition for forming the first liquid crystal layer 220 is coated on the surface of the formed alignment film to orient the liquid crystal compound 218, and then dried. If necessary, the composition is cured by ultraviolet irradiation or the like to form the first liquid crystal layer 220.

[0136] Next, the composition for forming the second liquid crystal layer 224 is coated onto the surface of the formed first liquid crystal layer 220 and dried. The composition is then cured by ultraviolet irradiation or the like as needed to form the second liquid crystal layer 224 and to form the first group of liquid crystal layers.

[0137] Here, if a liquid crystal layer is formed on a liquid crystal layer by a coating method, the upper liquid crystal layer follows the orientation of the liquid crystal compound on the surface of the lower liquid crystal layer.

[0138] Therefore, at the interface between the first liquid crystal layer 220 and the second liquid crystal layer 224, the orientation direction of the liquid crystal compound 218 of the first liquid crystal layer 220 is parallel (consistent) with the orientation direction of the liquid crystal compound 218 of the second liquid crystal layer 224.

[0139] Next, the composition for forming the first liquid crystal layer 220 is coated onto the surface of the formed second liquid crystal layer 224 and dried. If necessary, the composition is cured by ultraviolet irradiation or the like to form the first liquid crystal layer 220.

[0140] In the liquid crystal polarization interference element 216 constituting the optical element 210 of the present invention, the twist angles of the thickness direction twist of the liquid crystal compound 218 in the first liquid crystal layer 220 and the twist angles of the thickness direction twist of the liquid crystal compound 218 in the second liquid crystal layer are equal, and the twist directions are opposite. Therefore, if the orientation angle of the liquid crystal compound 218 at the interface between the first liquid crystal layer 220 formed on the surface of the alignment film and the alignment film is set to 0°, the orientation angle of the liquid crystal compound 218 on the upper surface of the second liquid crystal layer 224 also returns to 0°.

[0141] Furthermore, as described above, if a liquid crystal layer is formed on a liquid crystal layer by a coating method, the liquid crystal compound in the vicinity of the interface between the upper liquid crystal layer and the lower layer follows the orientation of the liquid crystal compound on the surface of the lower liquid crystal layer.

[0142] Therefore, at the interface between the second liquid crystal layer 224 and the first liquid crystal layer 220, the orientation direction of the liquid crystal compound 218 of the second liquid crystal layer 224 is parallel to the orientation direction of the liquid crystal compound 218 of the first liquid crystal layer 220 at 0°.

[0143] Next, a second liquid crystal layer 224 is formed on the surface of the first liquid crystal layer 220. Then, the first liquid crystal layer 220 is formed on the surface of the second liquid crystal layer 224. The process of forming the second liquid crystal layer 224 on the surface of the first liquid crystal layer 220 is repeated only until the number of liquid crystal layers formed, i.e. the number of liquid crystal layer groups formed, is used to fabricate a liquid crystal polarization interference element 216.

[0144] Furthermore, for example, the angle between the orientation direction of the liquid crystal compound 218 in the initially formed first liquid crystal layer 220 and the in-plane slow axis of the first λ / 4 sheet 212 is set to 45°, and the second λ / 4 sheet 214 is arranged such that the in-plane slow axis of the first λ / 4 sheet 212 is orthogonal to the in-plane slow axis of the second λ / 4 sheet 212, and the liquid crystal polarization interference element 216 is sandwiched in the thickness direction (stack direction), thus setting it as follows. Figure 1 The optical component 210 shown.

[0145] In addition, in the above, the angle between the orientation direction of the liquid crystal compound 218 in the first liquid crystal layer 220 and the in-plane slow axis of the first λ / 4 sheet 212 is set to 45°, but the angle can be 45°±15°, preferably 45°±10°.

[0146] Furthermore, in the liquid crystal polarization interference element 216 of the optical element 210 of the present invention, the first liquid crystal layer 220 and the second liquid crystal layer 224 are not limited to directly stacked layers formed by the coating method as described above. That is, the liquid crystal polarization interference element 216 can be an element formed by fabricating sheet-like first liquid crystal layer 220 and second liquid crystal layer 224, stacking them alternately, and bonding them with an adhesive that is transparent to transmitted light, such as OCA and acrylic adhesive.

[0147] From the viewpoint of transmittance of transmitted light, the first liquid crystal layer 220 and the second liquid crystal layer 224, which are directly stacked based on a coating method and do not have an adhesive layer, are preferred.

[0148] In the optical element 210 (liquid crystal polarizing interference element 216) of the present invention, there is no limitation on the liquid crystal compound 218 (rod-shaped liquid crystal compound), and various known liquid crystal compounds can be used.

[0149] As rod-shaped liquid crystal compounds, preferred materials include imine derivatives, azo derivatives, cyanobiphenyl derivatives, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane derivatives, cyano-substituted phenylpyrimidine derivatives, alkoxy-substituted phenylpyrimidine derivatives, phenyl dioxane derivatives, diphenylacetylene derivatives, and alkenylcyclohexylbenzyl nitrile derivatives. Not only low-molecular-weight liquid crystal molecules like those mentioned above can be used, but also high-molecular-weight liquid crystal molecules.

[0150] In the first liquid crystal layer 220 and the second liquid crystal layer 224, it is more preferable to fix the orientation of the rod-shaped liquid crystal compound by polymerization. As a polymerizable rod-shaped liquid crystal compound, it can be used in Makromol. Chem., Vol. 190, pp. 2255 (1989), Advanced Materials. Compounds described in 5 volumes, 107 pages (1993), U.S. Patent No. 4,683,327, U.S. Patent No. 5,622,648, U.S. Patent No. 5,770,107, International Publication No. 95 / 22586, International Publication No. 95 / 24455, International Publication No. 97 / 00600, International Publication No. 98 / 23580, International Publication No. 98 / 52905, Japanese Patent Application Publication No. 1-272,551, Japanese Patent Application Publication No. 6-16616, Japanese Patent Application Publication No. 7-110,469, Japanese Patent Application Publication No. 11-80081, and Japanese Patent Application Publication No. 2001-64627. Furthermore, as rod-shaped liquid crystal compounds, compounds described in Japanese Patent Application Publication No. 11-513019 and Japanese Patent Application Publication No. 2007-279688 are preferred.

[0151] As mentioned above, chiral agents have the function of inducing twisted orientation of liquid crystal compounds along the thickness direction. The direction of helical twist or the helical pitch induced by the chiral agent varies depending on the compound; therefore, it can be selected according to the purpose.

[0152] There are no particular restrictions on the use of chiral reagents, and well-known compounds can be used (e.g., described in Liquid Crystal Devices Handbook, Chapter 3, Item 4-3, TN (twisted nematic), STN (Super Twisted Nematic) chiral reagents, page 199, edited by Committee 142 of the Japan Society for the Promotion of Science, 1989), isosorbide (a chiral reagent with an isosorbide structure), and isomannitol derivatives, etc.

[0153] Furthermore, chiral reagents that undergo deisomerization, dimerization, and isomerization and dimerization through light irradiation, and chiral reagents that reduce helical twisting power (HTP) can also be preferentially utilized.

[0154] Chiral reagents typically contain asymmetric carbon atoms, but axially chiral compounds or planar chiral compounds that do not contain asymmetric carbon atoms can also be used as chiral reagents. Examples of axially chiral compounds or planar chiral compounds include binaphthyl, helicene, p-cycloaranes, and their derivatives. Chiral reagents may also have polymerizable groups. When both the chiral reagent and the liquid crystal compound have polymerizable groups, a polymer having repeating units derived from the polymeric liquid crystal compound and repeating units derived from the chiral reagent can be formed by the polymerization reaction of the polymerizable chiral reagent and the polymeric liquid crystal compound. In this manner, the polymerizable groups possessed by the polymerizable chiral reagent are preferably groups of the same kind as those possessed by the polymeric liquid crystal compound. Therefore, the polymerizable groups of the chiral reagent are preferably unsaturated polymerizable groups, epoxy groups, or aziridinyl groups, more preferably unsaturated polymerizable groups, and even more preferably olefinic unsaturated polymerizable groups.

[0155] Furthermore, the chiral reagent can also be a liquid crystal compound.

[0156] When the chiral reagent has a photoisomerizing group, it is preferable that a pattern corresponding to the desired reflection wavelength is formed by irradiation with a photomask such as activated light after coating and orientation. As the photoisomerizing group, it is preferable to be an isomerization site of a compound exhibiting photochromic properties, an azo group, an oxyazo group, or a cinnamyl group. As specific compounds, the compounds described in Japanese Patent Application Publication Nos. 2002-080478, 2002-080851, 2002-179668, 2002-179669, 2002-179670, 2002-179681, 2002-179682, 2002-338575, 2002-338668, 2003-313189, and 2003-313292 may be used.

[0157] The twist angle in the thickness direction of liquid crystal compound 218 varies depending on the amount of chiral reagent added.

[0158] Therefore, by selecting a chiral reagent and appropriately setting the amount added, the twisting direction and twisting angle of the liquid crystal compound 218 in the first liquid crystal layer 220 and the second liquid crystal layer 224 can be arbitrarily set.

[0159] In the composition used to form the first liquid crystal layer 220 and the second liquid crystal layer 224, in addition to the liquid crystal compound and the chiral reagent, polymerization initiators, leveling agents, crosslinking agents and surfactants may be added as needed.

[0160] exist Figure 1 In the optical components 210 shown, all first liquid crystal layers 220 are identical, and all second liquid crystal layers 224 are also identical. That is, in Figure 1 In the optical element 210 shown, the Δnd of all first liquid crystal layers 220 and the twist angle of liquid crystal compound 218 are equal, and the Δnd of all second liquid crystal layers 224 and the twist angle of liquid crystal compound 218 are equal.

[0161] However, the present invention is not limited to this, and the distribution of Δnd of the liquid crystal layer and the twist angle of the liquid crystal compound 218 in the thickness direction can also be present. That is, in the optical elements of the present invention, if Δnd is equal in the first liquid crystal layer and the second liquid crystal layer, and the twist directions of the liquid crystal compound 218 are opposite and the twist angles (absolute values ​​of the twist angles) are equal, then substances with different Δnd and twist angles of the liquid crystal compound 218 can exist between the liquid crystal layer groups.

[0162] As an example, a structure in which the Δnd of the liquid crystal layer and the twist angle of the liquid crystal compound 218 are different in the central liquid crystal layer group in the thickness direction (stack direction) and the liquid crystal layer groups on both sides of the thickness direction can be illustrated.

[0163] Specifically, the Δnd of the liquid crystal layer on both sides of the liquid crystal layer group in the thickness direction can be made greater than the Δnd of the liquid crystal layer layer in the central liquid crystal layer group in the thickness direction, and the twist angle of the liquid crystal compound 218 can be made smaller than the twist angle of the liquid crystal layer layer in the central liquid crystal layer group in the thickness direction.

[0164] As an example, in the case where the optical element (liquid crystal polarizing interference element) has 8 liquid crystal layers, i.e., 4 groups of liquid crystal layers,

[0165] In the first group of liquid crystal layers, the Δnd of the first liquid crystal layer (layer 1) is set to Δnd1, and the twist angle of the liquid crystal compound is set to φ1. Similarly, the Δnd of the second liquid crystal layer (layer 2) is set to Δnd1, and the twist angle of the liquid crystal compound is set to -φ1.

[0166] In the second group of liquid crystal layers, the Δnd of the first liquid crystal layer (third layer) is set to Δnd2, which is less than Δnd1, and the twist angle of the liquid crystal compound is set to φ2, which is greater than φ1. The Δnd of the second liquid crystal layer (fourth layer) is set to Δnd2, and the twist angle of the liquid crystal compound is set to -φ2.

[0167] In the third group of liquid crystal layers, the Δnd of the first liquid crystal layer (the fifth layer) is set to Δnd2, and the twist angle of the liquid crystal compound is set to φ2. The Δnd of the second liquid crystal layer (the sixth layer) is set to Δnd2, and the twist angle of the liquid crystal compound is set to -φ2.

[0168] In the fourth group of liquid crystal layers, an example can be shown where the Δnd of the first liquid crystal layer (the seventh layer) is set to Δnd1, the twist angle of the liquid crystal compound is set to φ1, the Δnd of the second liquid crystal layer (the eighth layer) is set to Δnd1, and the twist angle of the liquid crystal compound is set to -φ1.

[0169] As described above, the liquid crystal polarizing interference element acts as a λ / 2 phase retardation plate for light in a specific wavelength region that is the target, but does not act as a phase retardation layer for other light. On the other hand, when linear polarizers arranged in orthogonal Nicol positions are placed above and below the liquid crystal polarizing interference element, such as... Figure 3Conceptually, the liquid crystal polarization interferometer functions as a bandpass filter centered on a specific wavelength region. That is, in the above-described manner, it functions as a bandpass filter with high transmittance in a specific wavelength region and low transmittance in other wavelength regions. However, sometimes, within the specific wavelength region that is the target, transmission wavelength regions, referred to as side lobes (as shown by arrow S in the figure), are generated at positions shorter and longer than the target wavelength region. In other words, in the liquid crystal polarization interferometer, polarization components generated by the function of the λ / 2 phase difference plate are sometimes produced in wavelength regions other than the specific wavelength region.

[0170] In contrast, as described above, by making the Δnd of the liquid crystal layers on both sides of the thickness direction greater than the Δnd of the liquid crystal layer in the central liquid crystal layer group in the thickness direction, and by making the twist angle of the liquid crystal compound 218 smaller than the twist angle of the liquid crystal layer in the central liquid crystal layer group in the thickness direction, the sidelobe can be reduced. That is, the polarization component generated by the function of the λ / 2 phase retardation plate can be reduced.

[0171] In addition, as an example, the Δnd of the liquid crystal layer can be adjusted by changing the thickness of the liquid crystal layer, but it can also be adjusted by changing the liquid crystal compound used.

[0172] Furthermore, the twist angle of the liquid crystal compound can be adjusted by changing the type and / or amount of the chiral reagent.

[0173] In a structure in which the Δnd of the liquid crystal layer groups on both sides of the thickness direction is greater than the Δnd of the liquid crystal layer group in the center of the thickness direction, and the twist angle of the liquid crystal compound 218 is smaller than the twist angle of the liquid crystal layer group in the center of the thickness direction, compared with the two sides, there is no restriction on the number of liquid crystal layers in the center where the Δnd of the liquid crystal layer is increased and the twist angle of the liquid crystal compound 218 is decreased. That is, the division method of the liquid crystal layer groups on both sides and the center is not limited. It can be set appropriately according to the number of liquid crystal layers (liquid crystal layer groups) of the liquid crystal polarization interference element of the optical element.

[0174] Furthermore, the optimal Δnd and twist angle of the liquid crystal layer and liquid crystal compound 218 in the liquid crystal layer group on both sides of the thickness direction, and the optimal Δnd and twist angle of the liquid crystal layer and liquid crystal compound 218 in the central liquid crystal layer group in the thickness direction, can be achieved by simulating the liquid crystal polarization interference element acting as a λ / 2 phase difference plate and reducing the side lobes when set as a bandpass filter as described above.

[0175] In addition, it is preferable to control the change in the twist angle of the liquid crystal compound 218 from both sides toward the center in the stacking direction (thickness direction) and the distribution of Δnd in the thickness direction of the liquid crystal layer of the liquid crystal layer group as smoothly and precisely as possible.

[0176] exist Figure 1 In the optical element 210 shown, in each liquid crystal layer, the liquid crystal compound 218 is a rod-shaped liquid crystal compound, and the liquid crystal layer is composed only of rod-shaped liquid crystal compounds, but the present invention is not limited thereto.

[0177] That is, in the optical elements of the present invention, the liquid crystal layer can be as follows: Figure 4 Like the first liquid crystal layer 232 and the second liquid crystal layer 234 of the optical element 230 shown, in addition to having liquid crystal compound 218, it also has a disk-shaped liquid crystal compound.

[0178] That is, either the rod-shaped liquid crystal compound or the disk-shaped liquid crystal compound can be included in the liquid crystal compound in the first liquid crystal layer 232, and the other can be included in the liquid crystal compound in the second liquid crystal layer 234.

[0179] Furthermore, in the following description, to clearly distinguish it from the disc-shaped liquid crystal compound 240, liquid crystal compound 218 will also be referred to as rod-shaped liquid crystal compound 218. And, in Figure 4 In the optical components 230 shown, the same symbols are used to mark the same parts. The following mainly describes the different parts.

[0180] exist Figure 4 In the optical component 230 shown, the first liquid crystal layer 232 and the second liquid crystal layer 234 are liquid crystal layers formed by fixing rod-shaped liquid crystal compound 218 and disk-shaped liquid crystal compound 240 that are twisted and oriented along the thickness direction.

[0181] Furthermore, in the optical element 230, the twisting directions of the liquid crystal compounds in the first liquid crystal layer 232 and the second liquid crystal layer 234 are opposite, and the twisting angles of the liquid crystal compounds are the same. That is, the combined twisting angle of the rod-shaped liquid crystal compound 218 and the disk-shaped liquid crystal compound 240 in the first liquid crystal layer 232 and the second liquid crystal layer 234 is, in the same way as in the previous example, a relationship between "φ" and "-φ".

[0182] Furthermore, in the optical element 230, the orientation direction of the liquid crystal compound is also parallel at the interface between the first liquid crystal layer 232 and the second liquid crystal layer 234.

[0183] exist Figure 4In the optical element 230 shown, the first liquid crystal layer 232 is firstly provided with a rod-shaped liquid crystal compound 218 twisted along the thickness direction from bottom to top in the figure, and then provided with a disk-shaped liquid crystal compound 240 twisted along the thickness direction.

[0184] Conversely, in the second liquid crystal layer 234, in the thickness direction from bottom to top in the figure, the disk-shaped liquid crystal compound 240 is first oriented in a twisted manner along the thickness direction, and then the rod-shaped liquid crystal compound 218 is oriented in a twisted manner along the thickness direction. In the first liquid crystal layer 232 and the second liquid crystal layer 234, the twisted orientations of the liquid crystal compounds are opposite.

[0185] The optical element 230 also includes a liquid crystal polarization interference element 246 formed by alternating layers of a first liquid crystal layer 232 and a second liquid crystal layer 234, and the liquid crystal polarization interference element 246 has two or more groups of liquid crystal layers composed of the first liquid crystal layer 232 and the second liquid crystal layer 234.

[0186] exist Figure 4 In the example shown, in the liquid crystal layer group 236, the order from bottom to top in the thickness direction is: the first liquid crystal layer 232 is a "rod-shaped liquid crystal compound / disc-shaped liquid crystal compound", and the second liquid crystal layer 234 is a "disc-shaped liquid crystal compound / rod-shaped liquid crystal compound". However, the present invention is not limited to this. For example, in the optical elements of the present invention, in the liquid crystal layer group, the order from bottom to top in the thickness direction can be: the first liquid crystal layer is a "rod-shaped liquid crystal compound / disc-shaped liquid crystal compound", and the second liquid crystal layer is a "rod-shaped liquid crystal compound / disc-shaped liquid crystal compound".

[0187] Furthermore, under the condition that the sum of Δnd of each liquid crystal layer and the twist angle of the liquid crystal compound remains unchanged, the number, order and thickness of the regions composed of rod-shaped liquid crystal compound 218 and the regions composed of disk-shaped liquid crystal compound 240 can be appropriately changed.

[0188] like Figure 5 As conceptually shown, in a bandpass filter using the aforementioned liquid crystal polarizing interference element 216, when light is incident from an oblique direction, a wavelength shift occurs, causing the transmission wavelength region to move towards the shorter wavelength side.

[0189] In contrast, as with the liquid crystal polarization interference element 246, the first liquid crystal layer 232 and the second liquid crystal layer 234 have regions composed of rod-shaped liquid crystal compounds 218 and regions composed of disk-shaped liquid crystal compounds 240, thereby reducing the phase difference (Rth) in the thickness direction of the first liquid crystal layer 232 and the second liquid crystal layer 234, resulting in wavelength shift (color change) when light is incident from an oblique direction. That is, even if circularly polarized light is incident from a direction oblique to the normal direction of the surface of the optical element 230, it is possible to convert only the circularly polarized light in the set specific wavelength region into circularly polarized light with the opposite rotation direction.

[0190] When the first liquid crystal layer 232 and the second liquid crystal layer 234 are composed of a region containing a rod-shaped liquid crystal compound 218 and a region containing a disk-shaped liquid crystal compound 240, there is no limitation on the thickness ratio of the region composed of the rod-shaped liquid crystal compound 218 to the region composed of the disk-shaped liquid crystal compound 240.

[0191] Here, when the first liquid crystal layer 232 and the second liquid crystal layer 234 are composed of a region containing a rod-shaped liquid crystal compound 218 and a region containing a disk-shaped liquid crystal compound 240, it is preferable that the Δnd of the liquid crystal layer occupies half in the region containing the rod-shaped liquid crystal compound 218 and half in the region containing the disk-shaped liquid crystal compound 240, depending on the Δn of the liquid crystal compound used.

[0192] Furthermore, from the viewpoint of reducing interface reflection, the Δn of the rod-shaped liquid crystal compound 218 and the disk-shaped liquid crystal compound 240 is preferably the same, but compounds with different Δn can also be used.

[0193] Furthermore, regarding the liquid crystal polarization interference element 246, which is composed of a liquid crystal layer having regions composed of rod-shaped liquid crystal compounds 218 and regions composed of disk-shaped liquid crystal compounds 240, it can also be formed by coating using a composition that forms the regions composed of rod-shaped liquid crystal compounds 218 in the first liquid crystal layer 232, a composition that forms the regions composed of disk-shaped liquid crystal compounds 240 in the first liquid crystal layer 232, a composition that forms the regions composed of disk-shaped liquid crystal compounds 240 in the second liquid crystal layer 234, and a composition that forms the regions composed of rod-shaped liquid crystal compounds 218 in the second liquid crystal layer 234.

[0194] In the case where a region composed of a disc-shaped liquid crystal compound 240 is formed on a region composed of a rod-shaped liquid crystal compound 218, and in the case where a region composed of a rod-shaped liquid crystal compound 218 is formed on a region composed of a disc-shaped liquid crystal compound 240, the liquid crystal compound in the region formed in the upper region follows the orientation direction (length direction) of the liquid crystal compound in the lower region, just as described above.

[0195] Therefore, even in a single liquid crystal layer, the liquid crystal compounds are continuously twisted and oriented in the thickness direction, and the orientation directions of the liquid crystal compounds at the interface between the first liquid crystal layer 232 and the second liquid crystal layer 234 are parallel.

[0196] Furthermore, in this invention, as described above, not only can liquid crystal layers (regions) be directly stacked by coating, but sheet-like liquid crystal layers can also be stacked and bonded using OCA or the like.

[0197] Furthermore, in this invention, a liquid crystal layer group consisting of a first liquid crystal layer 232 and a second liquid crystal layer 234 can be formed in one step by coating a composition comprising a disk-shaped liquid crystal compound 240 and a rod-shaped liquid crystal compound 218.

[0198] In this invention, when the first liquid crystal layer 232 and the second liquid crystal layer 234 have regions composed of a disk-shaped liquid crystal compound 240, there is no limitation on the disk-shaped liquid crystal compound used, and various known disk-shaped liquid crystal compounds can be used.

[0199] As a disc-shaped liquid crystal compound, the disc-shaped liquid crystal compound described in Japanese Patent Application Publication No. 2007-108732 and Japanese Patent Application Publication No. 2010-244038 is preferred.

[0200] Furthermore, when a disk-shaped liquid crystal compound is used in the liquid crystal layer, such as... Figure 4 As shown, the disk-shaped liquid crystal compound 240 is arranged upright in the thickness direction, and the optical axis derived from the liquid crystal compound is defined as the axis perpendicular to the disk surface, the so-called fast axis.

[0201] and, Figure 4 The first liquid crystal layer 232 and the second liquid crystal layer 234 shown each have a region composed of a rod-shaped liquid crystal compound 218 and a region composed of a disk-shaped liquid crystal compound 240, but the present invention is not limited thereto.

[0202] That is, in the present invention, when the first liquid crystal layer and the second liquid crystal layer have regions composed of rod-shaped liquid crystal compounds and regions composed of disk-shaped liquid crystal compounds, one liquid crystal layer may have multiple regions composed of rod-shaped liquid crystal compounds and / or may have multiple regions composed of disk-shaped liquid crystal compounds.

[0203] The twist angle and twist direction of the liquid crystal compounds in the first liquid crystal layer 232 and the second liquid crystal layer 234 constituting the liquid crystal polarization interference element 246 can be detected by cutting the liquid crystal polarization interference element 246 along an inclined direction and analyzing the orientation direction of the liquid crystal on the surface of its cross-section. Each of these methods is described in detail in the aforementioned literature by Yohei Takahashi et al.

[0204] In the optical elements of the present invention, the first liquid crystal layer and the second liquid crystal layer may contain infrared absorbing pigments.

[0205] By including infrared-absorbing pigments in the first and second liquid crystal layers, the wavelength dispersion of the liquid crystal in the liquid crystal layers can be made paradispersive. As a result, the wavelength region of light in which the liquid crystal polarization interference element functions as a λ / 2 waveplate can be narrowed. That is, by adding infrared-absorbing pigments to the first and second liquid crystal layers to make the wavelength dispersion of the liquid crystal in the liquid crystal layers strong paradispersive, an optical element with a narrower wavelength region for converting circularly polarized light into circularly polarized light with the opposite rotation direction can be obtained.

[0206] As infrared absorbing pigments, various infrared absorbing pigments can be utilized to reduce the difference in refractive index between the x and y directions by being oriented in the same direction as the liquid crystal compound.

[0207] Infrared-absorbing pigments are not particularly limited as long as they absorb infrared light (e.g., light with wavelengths of 700–900 m). Among these, dichroic pigments are preferred. Furthermore, dichroic pigments refer to pigments that exhibit different absorbance along their long axis and short axis.

[0208] As infrared absorbing pigments, diketopyrrolopyrrole pigments, diimino pigments, phthalocyanine pigments, naphthalene phthalocyanine pigments, azo pigments, polymethyl pigments, anthraquinone pigments, pyranonium pigments, squaric acid cyanine pigments, triphenylmethane pigments, anthocyanin pigments, and aminoonium pigments can be used.

[0209] Furthermore, metal complex pigments and boron complex pigments can also be used as infrared absorbing pigments.

[0210] The details regarding infrared-absorbing pigments are described in International Publication No. 2019 / 044859.

[0211] There is no limit to the amount of infrared absorbing pigment added to the first and second liquid crystal layers, as long as it is appropriately set according to the width of the wavelength region required by the optical components to convert circularly polarized light into circularly polarized light with the opposite rotation direction.

[0212] In the optical elements of the present invention, the first liquid crystal layer and the second liquid crystal layer may contain a liquid crystal elastomer.

[0213] Regarding the first and second liquid crystal layers containing liquid crystal elastomers, even if a liquid crystal elastomer is used to form the liquid crystal layer, a liquid crystal layer formed from a conventional liquid crystal compound that is not an elastomer may also contain a liquid crystal elastomer.

[0214] Thus, by including liquid crystal elastomers in the first and second liquid crystal layers, the first and second liquid crystal layers can be elastic, and the thickness of the liquid crystal layers can be changed by stretching or contracting the optical elements in the planar direction.

[0215] By changing the thickness of the liquid crystal layer, the Δnd of the liquid crystal layer can be changed. As a result, in the optical element, the wavelength region of light that converts circularly polarized light into circularly polarized light with the opposite rotation direction can be changed. That is, the first and second liquid crystal layers contain a liquid crystal elastomer, thereby making the wavelength region variable by stretching and contracting the liquid crystal layer, i.e., the optical element, enabling active wavelength control in the optical element.

[0216] There are no restrictions on liquid crystal elastomers; various known liquid crystal elastomers can be used.

[0217] As an example of a liquid crystal elastomer, the liquid crystal elastomer prepared by means of a liquid crystal monomer, a chiral reagent, a crosslinking agent, and a plasticizer as described in Japanese Patent Application Publication No. 2020-131638 can be used. This imparts mechanical properties to the liquid crystal elastomer and gives it rubber elasticity, enabling deformation corresponding to the external force required for active wavelength control.

[0218] Furthermore, when forming the first and second liquid crystal layers using a conventional liquid crystal compound that is not an elastomer and adding a liquid crystal elastomer to impart elasticity, there is no limit to the amount of liquid crystal elastomer added. It is only necessary to appropriately set the control range of the wavelength region that converts circularly polarized light into circularly polarized light with the opposite rotation direction according to the required elasticity.

[0219] The optical element of this invention can be used at any wavelength. That is, the optical element of this invention can be used with any electromagnetic wave, such as ultraviolet light, visible light, infrared light, terahertz waves, and millimeter waves.

[0220] The optical elements of the present invention have been described in detail above, but the present invention is not limited to the above examples. Various improvements or modifications can be made without departing from the spirit of the present invention.

[0221] [Piece 1λ / 4 and piece 2λ / 4]

[0222] The optical elements of the present invention have a first λ / 4 piece and a second λ / 4 piece.

[0223] As described above, the first λ / 4 plate and the second λ / 4 plate are plates that have the function of converting linearly polarized light of a specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). There are no particular limitations on the first λ / 4 plate 212 and the second λ / 4 plate 214, and known λ / 4 plates can be used.

[0224] The in-plane delay Re(550) of the first λ / 4 piece 212 and the second λ / 4 piece 214 at a wavelength of 550 nm is preferably 100-200 nm, more preferably 120-160 nm, and even more preferably 130-150 nm.

[0225] The λ / 4 sheet can be composed of one layer or two or more layers. Preferably, the λ / 4 sheet has a layer containing a liquid crystal compound. When the λ / 4 sheet has a layer containing a liquid crystal compound, the layer containing the liquid crystal compound can be a layer formed by fixing a liquid crystal compound horizontally oriented in one direction, or a layer formed by fixing a liquid crystal compound twistedly oriented in the thickness direction.

[0226] Furthermore, a λ / 4 sheet can be a so-called broadband λ / 4 sheet formed by stacking layers that produce a λ / 4 phase difference and layers that produce a λ / 2 phase difference.

[0227] Preferably, at least one of the first λ / 4 sheet 212 and the second λ / 4 sheet 214 is a laminate composed of a liquid crystal layer A formed by fixing a liquid crystal compound twisted and oriented along the thickness direction and a liquid crystal layer B formed by fixing a liquid crystal compound twisted and oriented along the thickness direction. More preferably, the first λ / 4 sheet 212 and the second λ / 4 sheet 214 are a laminate composed of the liquid crystal layer A and the liquid crystal layer B.

[0228] Furthermore, when the first λ / 4 sheet 212 is a laminate composed of the liquid crystal layer A and the liquid crystal layer B, it is preferable that the orientation direction of the liquid crystal compound on the surface of the first liquid crystal layer 220 side of the first λ / 4 sheet 212 is parallel to the orientation direction of the liquid crystal compound on the surface of the first liquid crystal layer 220 on the surface of the first liquid crystal layer 220.

[0229] Furthermore, when the second λ / 4 sheet 214 is a laminate composed of the liquid crystal layer A and the liquid crystal layer B, it is preferable that the orientation direction of the liquid crystal compound 18 on the surface of the second liquid crystal layer 224 side of the second λ / 4 sheet 214 is parallel to the orientation direction of the liquid crystal compound on the surface of the second liquid crystal layer 224 side of the second liquid crystal layer 224.

[0230] The preferred λ / 4-piece configuration (Method 1 and Method 2) will be explained below.

[0231] (Method 1)

[0232] The preferred first embodiment of the λ / 4 sheet used in the optical components of the present invention is a laminate consisting of a liquid crystal layer A formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction and a liquid crystal layer B formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction.

[0233] In this first embodiment, the twisting direction of the liquid crystal compound in liquid crystal layer A is the same as the twisting direction of the liquid crystal compound in liquid crystal layer B, the twisting angle of the liquid crystal compound in liquid crystal layer A is 26.5±10.0°, and the twisting angle of the liquid crystal compound in liquid crystal layer B is 78.6±10.0°.

[0234] Furthermore, the in-plane slow axis of the surface of liquid crystal layer A on the side of liquid crystal layer B is parallel to the in-plane slow axis of the surface of liquid crystal layer B on the side of liquid crystal layer A.

[0235] Furthermore, the refractive index anisotropy Δn of liquid crystal layer A was measured at a wavelength of 550 nm. A With respect to the thickness d of liquid crystal layer A A The product Δn A ·d A The value and the refractive index anisotropy Δn of liquid crystal layer B measured at a wavelength of 550 nm. B With respect to the thickness d of liquid crystal layer B B The product Δn B ·d B The values ​​of satisfy the following equations (A1) and (B1) respectively.

[0236] Equation (A1) 252nm≤Δn A ·d A ≤312nm

[0237] Equation (B1) 110nm≤Δn B ·d B ≤170nm

[0238] The twist angle of the liquid crystal compound in liquid crystal layer A is preferably 26.5±8.0°, more preferably 26.5±6.0°.

[0239] The twist angle of the liquid crystal compound in liquid crystal layer B is preferably 78.6±8.0°, more preferably 78.6±6.0°.

[0240] The torsion angle can be measured using the Axoscan (polarimeter) device from Axometrics and the company's analysis software.

[0241] Furthermore, regarding the aforementioned Δn A ·d A The value and Δn B ·d B The value of is preferably satisfied by the following equations (A2) and (B2).

[0242] Equation (A2) 262nm≤Δn A ·d A ≤302nm

[0243] Equation (B2) 120nm≤Δn B ·d B ≤160nm

[0244] Regarding Δn A ·d A The value and Δn B ·d B Similar to the method for measuring the torsion angle, the Axoscan (polarimeter) device from Axometrics can be used, along with the company's analysis software, for measurement.

[0245] Furthermore, regarding the aforementioned Δn A ·d A The value and Δn B ·d B The value of is more preferably satisfied by the following equations (A3) and (B3).

[0246] Equation (A3) 272nm≤Δn A ·d A ≤292nm

[0247] Formula (B3)130nm≤Δn B ·d B ≤150nm

[0248] An alignment film that can restrict the orientation direction of the liquid crystal compound can be disposed between liquid crystal layer A and liquid crystal layer B. However, from the viewpoint of better adhesion between liquid crystal layer A and liquid crystal layer B, it is preferable not to dispose of an alignment film between liquid crystal layer A and liquid crystal layer B.

[0249] The type of liquid crystal compound used to form liquid crystal layer A and liquid crystal layer B is not particularly limited. For example, liquid crystal layer A and liquid crystal layer B can also be obtained by immobilizing a low molecular weight liquid crystal compound in a nematic orientation in a liquid crystal state through photocrosslinking or thermal crosslinking; and liquid crystal layer B obtained by immobilizing a high molecular weight liquid crystal compound in a nematic orientation in a liquid crystal state through cooling.

[0250] Generally, liquid crystal compounds can be classified into rod-shaped types (rod-shaped liquid crystal compounds) and disc-shaped types (disc-shaped liquid crystal compounds) according to their shape. Furthermore, there are low-molecular-weight and high-molecular-weight types. A high-molecular-weight compound typically refers to a substance with a degree of polymerization of 100 or higher (Polymer Physics / Phase Transition Dynamics, edited by Masao Doi, p. 2, Iwanami Shoten, 1992). In this invention, any liquid crystal compound can be used, but rod-shaped or disc-shaped liquid crystal compounds are preferred. Two or more rod-shaped liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or mixtures of rod-shaped and disc-shaped liquid crystal compounds can be used.

[0251] Furthermore, as a rod-shaped liquid crystal compound, for example, the compound described in paragraphs

[0026] to

[0098] of Japanese Patent Application Publication No. 11-513019 or Japanese Patent Application Publication No. 2005-289980 can be preferred, and as a disc-shaped liquid crystal compound, for example, the compound described in paragraphs

[0020] to

[0067] of Japanese Patent Application Publication No. 2007-108732 or Japanese Patent Application Publication No. 2010-244038 can be preferred, but it is not limited to these.

[0252] From the viewpoint of reducing temperature or humidity changes, liquid crystal layer A or liquid crystal layer B is more preferably formed using rod-shaped or disc-shaped liquid crystal compounds having polymerizable groups. The liquid crystal compound can be a mixture of two or more compounds; in this case, it is preferable that at least one compound has two or more polymerizable groups.

[0253] That is, liquid crystal layer A or liquid crystal layer B is preferably a layer formed by fixing rod-shaped liquid crystal compound or disk-shaped liquid crystal compound with polymerizable groups through polymerization or the like. In this case, after becoming a layer, it is not necessary to display liquid crystal properties.

[0254] The types of polymerizable groups contained in the disc-shaped and rod-shaped liquid crystal compounds are not particularly limited, but functional groups capable of undergoing addition polymerization are preferred, and polymerizable olefinic unsaturated groups or cyclic polymerizable groups are preferred. More specifically, (meth)acryloyl, vinyl, styrene, allyl, etc. are preferred, and (meth)acryloyl is more preferred.

[0255] λ / 4 wafers can be manufactured using various methods. One such method is described below.

[0256] First, a support such as a polymer film and a glass plate is prepared. An alignment film is formed on the support as needed. A liquid crystal compound having polymerizable groups and a liquid crystal layer A forming composition, including additives such as chiral reagents as needed, are coated onto the surface of the support or the alignment film to form a coating film. The coating film is then heated as needed to twist and align the molecules of the liquid crystal compound. Afterward, it is cooled to a curing temperature and polymerized by a curing treatment (ultraviolet irradiation (light irradiation treatment) or heat treatment) to fix the twisted orientation, thereby obtaining a liquid crystal layer A with optical rotation. The coating of the liquid crystal composition can be carried out using known methods (e.g., wire rod coating, extrusion coating, direct gravure coating, reverse gravure coating, mold coating) to apply a coating liquid containing the solvent described later. Furthermore, it can be formed by inkjet printing.

[0257] Next, a liquid crystal compound having polymerizable groups and a liquid crystal layer B forming composition containing additives such as chiral reagents, which are applied to liquid crystal layer A (or, if necessary, the surface of an alignment film formed thereon), are coated to form a coating film. Then, the liquid crystal compound having polymerizable groups in the aligned state is cured (heat treatment or light irradiation treatment) to form liquid crystal layer B.

[0258] In addition, liquid crystal layer A can be directly coated on Figure 1 The liquid crystal layer B is formed on the liquid crystal polarization interference element 216 shown in the figure. Furthermore, the liquid crystal layer B can be directly coated on the liquid crystal polarization interference element 216, and the liquid crystal layer A is formed on the side of the liquid crystal layer B opposite to the side of the liquid crystal polarization interference element 216.

[0259] Thus, if liquid crystal layer A is formed by directly coating it onto the liquid crystal polarization interference element 216, the orientation direction of the liquid crystal compound on the surface of liquid crystal layer A of the liquid crystal polarization interference element 216 easily becomes parallel to the orientation direction of the liquid crystal compound on the surface of liquid crystal layer A on the surface of liquid crystal polarization interference element 216. Furthermore, if liquid crystal layer B is formed by directly coating it onto the liquid crystal polarization interference element 216, the orientation direction of the liquid crystal compound on the surface of liquid crystal layer B on the surface of liquid crystal polarization interference element 216 easily becomes parallel to the orientation direction of the liquid crystal compound on the surface of liquid crystal layer B on the surface of liquid crystal polarization interference element 216.

[0260] The oriented (preferably vertically oriented) liquid crystal compound is preferably maintained in its oriented state and immobilized. Immobilization is preferably carried out by initiating a polymerization reaction of the polymerizable groups introduced into the liquid crystal compound using a polymerization initiator. The polymerization reaction may include a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. Photopolymerization is preferred.

[0261] The amount of polymerization initiator used is preferably 0.01 to 20% by mass of the solid component of the composition, more preferably 0.5 to 5% by mass.

[0262] When forming liquid crystal layers A and B, chiral reagents may be used together with the aforementioned liquid crystal compound as needed. The chiral reagent is added to orient the liquid crystal compound to a twisted shape. However, if the liquid crystal compound contains optically active compounds such as asymmetric carbon atoms within its molecule, the addition of a chiral reagent is unnecessary. Furthermore, depending on the manufacturing method and the twist angle, the addition of a chiral reagent may or may not be required.

[0263] As a chiral reagent, there are no particular restrictions on its structure, as long as it is a substance compatible with the liquid crystal compound used simultaneously. Any known chiral reagent can also be used (e.g., "Handbook of Liquid Crystal Devices," Chapter 3, Items 4-3, TN and STN using chiral reagents, page 199, mid-1989, edited by Committee 142 of the Japan Society for the Promotion of Science). Chiral reagents typically contain asymmetric carbon atoms, but axially chiral compounds or planar chiral compounds that do not contain asymmetric carbon atoms can also be used as chiral reagents. Examples of axially chiral compounds or planar chiral compounds include naphthalene, helicene, p-xylene dimers, and their derivatives. Furthermore, the chiral reagent can possess liquid crystal properties.

[0264] Plasticizers, surfactants, polymerizable monomers, etc., can be used simultaneously with the aforementioned liquid crystal compounds to improve the uniformity of the coated film, the film strength, and the orientation of the liquid crystal compound. These raw materials preferably have compatibility with the liquid crystal compound and do not hinder orientation.

[0265] Furthermore, in order to make the liquid crystal compound be in a horizontally or vertically oriented state, additives (orientation control agents) that promote horizontal and vertical orientation can be used. As additives, various known additives can be used.

[0266] Examples of polymerizable monomers include free radical polymerizable compounds and cationic polymerizable compounds. Multifunctional free radical polymerizable monomers are preferred, and compounds copolymerized with the aforementioned liquid crystal compounds containing polymerizable groups are even more preferred. For example, compounds described in paragraphs

[0018] to

[0020] of Japanese Patent Application Publication No. 2002-296423 can be cited. The amount of the aforementioned compound added is typically in the range of 1 to 50% by mass relative to the liquid crystal molecules, preferably in the range of 5 to 30% by mass.

[0267] As surfactants, conventionally known compounds can be cited, with fluorinated compounds being particularly preferred. Specifically, for example, compounds described in paragraphs

[0028] to

[0056] of Japanese Patent Application Publication No. 2001-330725 and compounds described in paragraphs

[0069] to

[0126] of Japanese Patent Application No. 2003-295212 can be cited.

[0268] The polymer used with the liquid crystal compound preferably has the ability to thicken the coating liquid. Examples of polymers include cellulose esters. A preferred example of a cellulose ester is the compound described in paragraph

[0178] of Japanese Patent Application Publication No. 2000-155216. To avoid hindering the orientation of the liquid crystal compound, the amount of the polymer added is preferably in the range of 0.1 to 10% by mass relative to the liquid crystal molecules, more preferably in the range of 0.1 to 8% by mass.

[0269] The disk-nematic liquid crystal phase-solid phase transition temperature of the liquid crystal compound is preferably 70 to 300°C, and more preferably 70 to 170°C.

[0270] Organic solvents are preferably used as solvents for preparing the composition (coating solution). Examples of organic solvents include amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents can be used simultaneously.

[0271] In the first method, a liquid crystal layer A forming composition or a liquid crystal layer B forming composition can be coated on the surface of the alignment film to orient the molecules of the liquid crystal compound (e.g., a discoid liquid crystal compound).

[0272] Alignment films can be formed by methods such as triboelectric treatment with organic compounds (preferably polymers), tilted evaporation of inorganic compounds, formation of layers with microgrooves, or accumulation of organic compounds (e.g., ω-trisanoic acid, dioctadecylmethylammonium chloride, methyl stearate) based on the Langmuir-Blodgett process (LB film). Furthermore, alignment films that acquire alignment functionality by applying an electric field, a magnetic field, or irradiation with light (preferably polarized light) are also known.

[0273] The orientation film is preferably formed by friction treatment of the polymer.

[0274] Examples of polymers include, for example, methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly(N-hydroxymethylacrylamide), polyesters, polyimides, vinyl acetate copolymers, carboxymethyl cellulose, polycarbonates, etc., as described in paragraph

[0022] of Japanese Patent Application Publication No. 8-338913. Silane coupling agents can be used as polymers. Water-soluble polymers are preferred (e.g., poly(N-hydroxymethylacrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol), more preferably gelatin, polyvinyl alcohol and modified polyvinyl alcohol, and most preferably polyvinyl alcohol and modified polyvinyl alcohol.

[0275] Regarding the alignment film, it can basically be formed by coating a solution containing the aforementioned polymer as the alignment film forming material and any additives (e.g., crosslinking agents) onto a transparent support, followed by heating and drying (to crosslink it), and then performing a friction treatment.

[0276] Friction processing is a widely used method in the liquid crystal alignment process of LCDs. Specifically, it involves rubbing the surface of the alignment film in a specific direction using materials such as paper or gauze, felt, rubber, nylon, or polyester fibers to achieve alignment. Typically, this is achieved by rubbing the film several times with a cloth containing evenly packed fibers of uniform length and thickness.

[0277] In the first embodiment where the λ / 4 sheet is preferably used in the optical elements of the present invention, the liquid crystal layer A is preferably disposed on the optical laminate side.

[0278] (Method 2)

[0279] The second preferred embodiment of the λ / 4 sheet used in the optical components of the present invention is a laminate consisting of a liquid crystal layer A formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction and a liquid crystal layer B formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction.

[0280] In the second embodiment, the twisting direction of the liquid crystal compound in liquid crystal layer A is the same as that of the liquid crystal compound in liquid crystal layer B, the twisting angle of the liquid crystal compound in liquid crystal layer A is 59.7±10.0°, and the twisting angle of the liquid crystal compound in liquid crystal layer B is 127.6±10.0°.

[0281] Furthermore, the in-plane slow axis of the surface of liquid crystal layer A on the side of liquid crystal layer B is parallel to the in-plane slow axis of the surface of liquid crystal layer B on the side of liquid crystal layer A.

[0282] Furthermore, the refractive index anisotropy Δn of liquid crystal layer A was measured at a wavelength of 550 nm. A With respect to the thickness d of liquid crystal layer A A The product Δn A ·dA The value and the refractive index anisotropy Δn of liquid crystal layer B measured at a wavelength of 550 nm. B With respect to the thickness d of liquid crystal layer B B The product Δn B ·d B The values ​​of satisfy the following equations (A4) and (B4) respectively.

[0283] Equation (A4) 111nm≤Δn A ·d A ≤171nm

[0284] Equation (B4) 252nm≤Δn B ·d B ≤312nm

[0285] The twist angle of the liquid crystal compound in liquid crystal layer A is preferably 59.7±8.0°, more preferably 59.7±6.0°.

[0286] The twist angle of the liquid crystal compound in liquid crystal layer B is preferably 127.6±8.0°, more preferably 127.6±6.0°.

[0287] The torsion angle can be measured using the Axoscan (polarimeter) device from Axometrics and the company's analysis software.

[0288] Furthermore, regarding the aforementioned Δn A ·d A The value and Δn B ·d B The value of is preferably satisfied by the following equations (A5) and (B5).

[0289] Equation (A5) 121nm≤Δn A ·d A ≤161nm

[0290] Equation (B5) 262nm≤Δn B ·d B ≤302nm

[0291] Regarding Δn A ·d A The value and Δn B ·d B Similar to the method for measuring the torsion angle, the Axoscan (polarimeter) device from Axometrics can be used, along with the company's analysis software, for measurement.

[0292] Furthermore, regarding the aforementioned Δn A ·d A The value and Δn B ·d BThe value of is more preferably satisfied by the following equations (A6) and (B6).

[0293] Equation (A6) 131nm≤Δn A ·d A ≤151nm

[0294] Equation (B6) 272nm≤Δn B ·d B ≤292nm

[0295] An alignment film that can restrict the orientation direction of the liquid crystal compound can be disposed between liquid crystal layer A and liquid crystal layer B. However, from the viewpoint of better adhesion between liquid crystal layer A and liquid crystal layer B, it is preferable not to dispose of an alignment film between liquid crystal layer A and liquid crystal layer B.

[0296] Furthermore, regarding the materials constituting liquid crystal layer A and liquid crystal layer B, examples of the materials constituting liquid crystal layer A and liquid crystal layer B described above can be given respectively.

[0297] Furthermore, the manufacturing methods of liquid crystal layer A and liquid crystal layer B are not particularly limited, and the manufacturing methods of liquid crystal layer A and liquid crystal layer B described above can be used as examples.

[0298] In the second embodiment where the λ / 4 sheet is preferably used in the optical elements of the present invention, the liquid crystal layer A is preferably disposed on the optical laminate side.

[0299] <Optical Components>

[0300] The optical element of the present invention comprises: a plurality of optically anisotropic layers formed using a composition comprising a liquid crystal compound, and having a liquid crystal alignment pattern that changes as the orientation of the optical axis originating from the liquid crystal compound rotates continuously in at least one in-plane direction; and the aforementioned optical element of the present invention disposed between at least one pair of adjacent optically anisotropic layers among the plurality of optically anisotropic layers.

[0301] Here, in the liquid crystal alignment pattern of the optical anisotropy layer, when the length of a 180° rotation of the orientation of the optical axis originating from the liquid crystal compound in one direction, which changes while rotating continuously, is defined as one cycle, the length of one cycle of at least one optical anisotropy layer is different from that of other optical anisotropy layers.

[0302] Furthermore, as described above, the optical element of the present invention acts as a wavelength-selective phase retardation plate for circularly polarized light. Hereinafter, the optical element of the present invention will sometimes be referred to as a "wavelength-selective phase retardation plate".

[0303] In the optical element of the present invention, the wavelength dependence of the refraction angle of the incident and transmitted light is small, and light of different wavelengths incident from the same direction can be emitted in almost the same direction.

[0304] An example of the optical element of the present invention is shown in Figure 6 .

[0305] Figure 6 The optical element 10 shown has a first optical anisotropy component 12 and a second optical anisotropy component 14, and a wavelength selective phase difference plate 18G disposed between the first optical anisotropy component 12 and the second optical anisotropy component 14.

[0306] As described above, the optical element of the present invention is an optical element formed by arranging an optically anisotropic layer having a predetermined liquid crystal alignment pattern derived from the optical axis rotation of the liquid crystal compound along the thickness direction using a composition containing a liquid crystal compound. The first optically anisotropic component 12 has a support 20, an alignment film 24A, and a first optically anisotropic layer 26A. Furthermore, the second optically anisotropic component 14 has a support 20, an alignment film 24B, and a second optically anisotropic layer 26B.

[0307] Furthermore, in the optical element of the present invention, as described above, the wavelength-selective retardation plate converts circularly polarized light in a specific wavelength region (the first wavelength region) into circularly polarized light with the opposite rotation direction, while light in the second wavelength region is directly transmitted (passes through unimpeded). In the optical element 10 of the example figure, the wavelength-selective retardation plate 18G converts the rotation direction of the circularly polarized light of green light into the opposite rotation direction, while other light is transmitted as circularly polarized light with the same rotation direction.

[0308] Although the illustration is omitted, the first optical anisotropic component 12 and the wavelength selective phase difference plate 18G, and the wavelength selective phase difference plate 18G and the second optical anisotropic component 14 are bonded together by bonding layers disposed between the layers.

[0309] Alternatively, the first optical anisotropic component 12, the wavelength selective phase difference plate 18G, and the second optical anisotropic component 14 can be stacked and held by a frame or clamp, thereby forming the optical element of the present invention.

[0310] Furthermore, as shown in the example figure, the optical element of the present invention is not limited to a structure in which the first optical anisotropic component 12, the wavelength selective phase difference plate 18G and the second optical anisotropic component 14 are closely packed and stacked, but can also utilize a structure in which one or more of these components are arranged separately.

[0311] Furthermore, the optical element 10 in the example figure has a support 20 in each optical anisotropic component, but the optical element of the present invention may not have a support 20 in each optical anisotropic component.

[0312] For example, the optical element of the present invention may have the following structure: a wavelength selective phase difference plate 18G is formed on the surface of the second optical anisotropic component 14 (the second optical anisotropic layer 26B), an alignment film 24A is formed thereon, and a first optical anisotropic layer 26A is formed thereon.

[0313] Alternatively, the support 20 of the second optical anisotropic component 14 can be peeled off from the above structure, and the optical element of the present invention can be composed only of the wavelength selective retardation plate, the alignment film and the optical anisotropic layer. Or the alignment film can be peeled off, and the optical element of the present invention can be composed only of the wavelength selective retardation plate and the optical anisotropic layer.

[0314] That is, in the optical element of the present invention, a plurality of optical anisotropic layers are arranged, and at least one pair of two adjacent optical anisotropic layers are provided with a wavelength selective phase retardation plate. Furthermore, the optical anisotropic layers have liquid crystal alignment patterns derived from the orientation of the optical axis of the liquid crystal compound rotating in one direction. Moreover, various layer structures can be utilized as long as the period of the liquid crystal alignment pattern of at least one optical anisotropic layer is different (described later).

[0315] [Optical anisotropic components]

[0316] The optical element 10 of the present invention has a wavelength selective phase difference plate 18G disposed between the first optical anisotropic component 12 and the second optical anisotropic component 14.

[0317] As described above, the first optical anisotropic component 12 has a support 20, an alignment film 24A, and a first optical anisotropic layer 26A. Furthermore, the second optical anisotropic component 14 has a support 20, an alignment film 24B, and a second optical anisotropic layer 26B.

[0318] (Support structure)

[0319] In the first optical anisotropic component 12 and the second optical anisotropic component 14, the support 20 supports the alignment film 24A and the alignment film 24B, as well as the first optical anisotropic layer 26A and the second optical anisotropic layer 26B.

[0320] In the following description, without needing to distinguish between alignment film 24A and alignment film 24B, alignment film 24A and alignment film 24B will be collectively referred to as "alignment film". Furthermore, in the following description, without needing to distinguish between the first optical anisotropic layer 26A and the second optical anisotropic layer 26B, the first optical anisotropic layer 26A and the second optical anisotropic layer 26B will also be collectively referred to as "optical anisotropic layer".

[0321] As long as it can support the alignment film and the optical anisotropic layer, the support 20 can utilize various sheet-like materials (films, plates).

[0322] (Orientation film)

[0323] In the first optical anisotropy component 12, an alignment film 24A is formed on the surface of the support 20. In the second optical anisotropy component 14, an alignment film 24B is formed on the surface of the support 20.

[0324] Alignment film 24A is an alignment film used to align liquid crystal compound 30 into a predetermined liquid crystal alignment pattern when forming the first optical anisotropic layer 26A of the first optical anisotropic component 12. Alignment film 24B is an alignment film used to align liquid crystal compound 30 into a predetermined liquid crystal alignment pattern when forming the second optical anisotropic layer 26B of the second optical anisotropic component 14.

[0325] Although described later, in the optical element 10 of the present invention, the optical anisotropy layer has an optical axis 30A derived from the liquid crystal compound 30 (see reference). Figure 6 The orientation of the liquid crystal alignment pattern changes as it rotates continuously in one direction (arrow X, described later). Therefore, the alignment film of each optically anisotropic component is formed in such a way that the optically anisotropic layer can form the liquid crystal alignment pattern.

[0326] Furthermore, in the optical element of the present invention, when the orientation of the optical axis 30A in the liquid crystal alignment pattern changes continuously in one direction, and the length of a 180° rotation of the orientation of the optical axis 30A is set as one cycle (the rotation cycle of the optical axis), the other optical anisotropies of at least one optical anisotropy layer are different from the length of one cycle of the liquid crystal alignment pattern. Figure 6 In the optical element 10 shown, one period (one period Λ) of the liquid crystal alignment pattern in the first optical anisotropy layer 26A. A ) compared to one period (one period Λ) of the liquid crystal alignment pattern in the second optical anisotropy layer 26B B )short.

[0327] In the following description, "orientation rotation of optical axis 30A" will also be referred to as "rotation of optical axis 30A".

[0328] Orientation films can utilize a variety of known orientation films.

[0329] Examples include triboelectric films composed of organic compounds such as polymers, tilted vapor-deposited films of inorganic compounds, films with microgrooves, and films formed by accumulating organic compounds such as ω-trisanoic acid, dioctadecylmethylammonium chloride, and methyl stearate using the Langmuir-Blodgett (LB) process.

[0330] Orientation films based on friction processing can be formed by rubbing the surface of a polymer layer several times in a specified direction with paper or cloth.

[0331] Examples of materials used in the alignment film include polyimide, polyvinyl alcohol, polymers with polymerizable groups as described in Japanese Patent Application Publication No. 9-152509, and materials used in the formation of alignment films as described in Japanese Patent Application Publication Nos. 2005-97377, 2005-99228, and 2005-128503.

[0332] In the optical element 10 of the present invention, the alignment film is preferably a so-called photoalignment film formed by irradiating polarized or unpolarized light with a raw material that is photooriented. That is, in the optical element 10 of the present invention, as the alignment film, a photoalignment film formed by coating a photoalignment material on a support 20 is preferably used.

[0333] Polarized light irradiation can be applied to the photo-alignment film from a vertical or inclined direction, while unpolarized light irradiation can be applied to the photo-alignment film from an inclined direction.

[0334] Examples of photoalignment materials that can be used in the photoalignment film of the present invention include, for example, Japanese Patent Application Publication Nos. 2006-285197, 2007-76839, 2007-138138, 2007-94071, 2007-121721, 2007-140465, and 2007-15. Azo compounds described in Japanese Patent Publication No. 6439, Japanese Patent Application Publication No. 2007-133184, Japanese Patent Application Publication No. 2009-109831, Japanese Patent Publication No. 3883848 and Japanese Patent Publication No. 4151746, aromatic ester compounds described in Japanese Patent Application Publication No. 2002-229039, and Japanese Patent Application Publication No. 2002-265541 and Japanese Patent Application Publication No. 2002-317013. The described maleimide and / or alkenyl-substituted nadicimide compounds having photooriented units, the photocrosslinkable silane derivatives described in Japanese Patent Nos. 4205195 and 4205198, the photocrosslinkable polyimides, photocrosslinkable polyamides and photocrosslinkable polyamides described in Japanese Patent Nos. 2003-520878, 2004-529220 and 4162850, are all examples of such compounds. Esters and photodimerizable compounds, particularly cinnamic acid esters, chalcone compounds and coumarin compounds, as described in Japanese Patent Application Publication Nos. 9-118717, 10-506420, 2003-505561, International Publication No. 2010 / 150748, 2013-177561 and 2014-12823, are preferred examples.

[0335] Among them, azo compounds, photocrosslinked polyimides, photocrosslinked polyamides, photocrosslinked esters, cinnamic acid ester compounds and chalcone compounds can be preferentially utilized.

[0336] There is no limit to the thickness of the alignment film; the required thickness for the alignment function can be obtained by appropriately setting the thickness according to the forming material of the alignment film.

[0337] The thickness of the alignment film is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm.

[0338] There are no restrictions on the method for forming the alignment film; various known methods corresponding to the materials used to form the alignment film can be used. As an example, a method can be illustrated by coating the alignment film onto the surface of the support 20, allowing it to dry, and then exposing the alignment film to a laser beam to form an alignment pattern.

[0339] exist Figure 17The image conceptually illustrates an example of an exposure apparatus for forming an alignment pattern by exposing an alignment film. Additionally, in... Figure 17 In the example shown, the exposure of the alignment film 24A of the first optical anisotropic component 12 is illustrated, but the alignment film 24B of the second optical anisotropic component 14 can also form an alignment pattern using the same exposure apparatus.

[0340] Figure 17 The exposure apparatus 60 shown includes: a light source 64 with a laser 62; a λ / 2 plate (not shown) for changing the polarization direction of the laser beam M emitted from the laser 62; a beam splitter 68 for separating the laser beam M emitted from the laser 62 and passing through the λ / 2 plate (not shown) into two beams, MA and MB; mirrors 70A and 70B respectively disposed on the optical paths of the two separated beams MA and MB; and λ / 4 plates 72A and 72B.

[0341] Additionally, although not illustrated, light source 64 includes a polarizer, emitting linearly polarized light P0. λ / 4 plates 72A and 72B have mutually orthogonal optical axes. λ / 4 plate 72A converts the linearly polarized light P0 (ray MA) into right-handed circularly polarized light P... R The λ / 4 72B plate converts linearly polarized light P0 (ray MB) into left-handed circularly polarized light P L .

[0342] A support 20 having an alignment film 24A before the alignment pattern is formed is disposed in the exposure unit, and two light rays MA and MB are made to cross and interfere on the alignment film 24A, thereby exposing the alignment film 24A with their interference light.

[0343] Through this interference, the polarization state of the light incident on the alignment film 24A changes periodically in the form of interference fringes. Thus, an alignment pattern with periodically changing alignment states can be obtained in the alignment film 24A.

[0344] In the exposure apparatus 60, the period of the alignment pattern can be adjusted by changing the cross angle α of the two light rays MA and MB. That is, in the exposure apparatus 60, by adjusting the cross angle α, in an alignment pattern in which the optical axis 30A originating from the liquid crystal compound 30 rotates continuously in one direction, the length of one cycle (one cycle Λ) of the optical axis 30A rotating 180° in the direction in which the optical axis 30A rotates can be adjusted.

[0345] By forming an optically anisotropic layer on an alignment film having an alignment pattern that periodically changes in such an alignment state, as described later, a first optically anisotropic layer 26A having a liquid crystal alignment pattern that continuously rotates in one direction from the optical axis 30A of the liquid crystal compound 30 can be formed.

[0346] Furthermore, the rotation direction of the optical axis 30A can be reversed by rotating the optical axes of the λ / 4 plates 72A and 72B by 90° respectively.

[0347] Furthermore, in the optical element of the present invention, the alignment film is an alignment film provided in a preferred manner, and is not a necessary component.

[0348] For example, an orientation pattern can be formed on the support 20 by a method of rubbing the support 20 or by processing the support 20 with a laser beam, etc., so that the first optical anisotropy layer 26a and the like can be configured to have a liquid crystal orientation pattern that changes as the orientation of the optical axis 30A originating from the liquid crystal compound 30 rotates continuously in at least one direction in the plane.

[0349] <<Optical Anisotropic Layer>>

[0350] In the first optical anisotropy component 12, a first optical anisotropy layer 26A is formed on the surface of the alignment film 24A. In the second optical anisotropy component 14, a second optical anisotropy layer 26B is formed on the surface of the alignment film 24B.

[0351] In addition, Figure 6 (and later) Figures 9-11 In order to simplify the drawings and clearly show the structure of the optical element 10, only the liquid crystal compound 30 (liquid crystal compound molecules) on the surface of the alignment film is shown in both the first optical anisotropic layer 26A and the second optical anisotropic layer 26B. However, as shown in the figure... Figure 7 As illustrated conceptually using the first optical anisotropy layer 26A as an example, the first optical anisotropy layer 26A and the second optical anisotropy layer 26B, like optical anisotropy layers formed using a composition containing a conventional liquid crystal compound, have a structure formed by stacking oriented liquid crystal compounds 30.

[0352] As described above, in the optical element 10 of the present invention, the optical anisotropy layers (the first optical anisotropy layer 26A and the second optical anisotropy layer 26B) are formed using a composition containing a liquid crystal compound.

[0353] When the in-plane delay is set to λ / 2, the optical anisotropic layer functions as a general λ / 2 sheet, that is, it imparts a half-wavelength, or 180° phase difference to the two orthogonal linearly polarized light components contained in the light incident on the optical anisotropic layer.

[0354] The optical anisotropic layer has a liquid crystal alignment pattern that changes as the orientation of the optical axis originating from the liquid crystal compound rotates continuously in a direction indicated by arrow X within the plane of the optical anisotropic layer.

[0355] Furthermore, the optical axis 30A originating from the liquid crystal compound 30 is the axis where the refractive index becomes the highest in the liquid crystal compound 30, also known as the slow axis. For example, in the case where the liquid crystal compound 30 is a rod-shaped liquid crystal compound, the optical axis 30A is along the long axis direction of the rod shape.

[0356] In the following description, "a direction indicated by arrow X" will also be referred to as "arrow X direction". Furthermore, in the following description, the optical axis 30A derived from the liquid crystal compound 30 will also be referred to as "optical axis 30A of liquid crystal compound 30" or "optical axis 30A".

[0357] In the optical anisotropic layer, the liquid crystal compound 30 is oriented in two dimensions in-plane, parallel to both the X-direction of the arrow and the Y-direction orthogonal to the X-direction. Furthermore, in... Figure 6 , Figure 7 The following Figures 9-11 In this case, the Y direction becomes the direction orthogonal to the plane of the paper.

[0358] Figure 8 The diagram shows a top view of the first optical anisotropy layer 26A.

[0359] Additionally, a top view refers to... Figure 6 The image shows the optical element 10 viewed from above, specifically from the thickness direction (i.e., the stacking direction of each layer (film)). In other words, it is a view of the first optical anisotropic layer 26A viewed from a direction orthogonal to the main surface.

[0360] Furthermore, in Figure 8 In order to clearly illustrate the structure of the optical element 10 of the present invention, and in conjunction with Figure 3 Similarly, only the liquid crystal compound 30 on the surface of the alignment film 24A is shown. However, as Figure 7 As shown, the first optical anisotropy layer 26A has a structure in the thickness direction formed by stacking liquid crystal compounds 30 from the surface of the alignment film 24A, as described above.

[0361] In addition, Figure 8 In this paper, the first optical anisotropic layer 26A is used as a representative example for explanation. However, the second optical anisotropic layer 26B has the same structure and function except that the length of one period (one period Λ) of the liquid crystal alignment pattern is different.

[0362] Furthermore, the rotation direction of the orientation of the optical axis 30A is opposite in the first optical anisotropy layer 26A and the second optical anisotropy layer 26B. That is, when the orientation of the optical axis 30A in the first optical anisotropy layer 26A rotates clockwise, the orientation of the optical axis 30A in the second optical anisotropy layer rotates counterclockwise.

[0363] The first optical anisotropic layer 26A has a liquid crystal alignment pattern that changes as it rotates continuously along the direction of arrow X within the plane of the first optical anisotropic layer 26A, originating from the optical axis 30A of the liquid crystal compound 30.

[0364] The orientation of the optical axis 30A of the liquid crystal compound 30 changes as it rotates continuously in the direction of arrow X (a specified direction). Specifically, the angle between the optical axis 30A of the liquid crystal compound 30 arranged along the direction of arrow X and the direction of arrow X varies depending on the position of the direction of arrow X. The angle between the optical axis 30A and the direction of arrow X changes sequentially from θ to θ+180° or θ-180°.

[0365] Furthermore, the angle difference between the optical axes 30A of adjacent liquid crystal compounds 30 in the direction of arrow X is preferably 45° or less, more preferably 15° or less, and even more preferably a smaller angle.

[0366] On the other hand, in the liquid crystal compound 30 forming the first optical anisotropic layer 26A, the liquid crystal compounds 30 with the same orientation of the optical axis 30A are arranged at equal intervals in the Y direction orthogonal to the direction of arrow X, that is, in the Y direction orthogonal to a direction in which the optical axis 30A is continuously rotated.

[0367] In other words, in the liquid crystal compound 30 forming the first optical anisotropic layer 26A, the orientation of the optical axis 30A of the liquid crystal compounds 30 arranged in the Y direction is equal to the angle formed by the arrow X direction.

[0368] In the optical element 10 of the present invention, in the liquid crystal alignment pattern of the liquid crystal compound 30, the length (distance) by which the optical axis 30A of the liquid crystal compound 30 is rotated 180° in the direction of arrow X, where the orientation of the in-plane optical axis 30A changes continuously by rotation, is defined as the length Λ of one cycle in the liquid crystal alignment pattern. In other words, the length of one cycle in the liquid crystal alignment pattern is defined by the distance from θ to θ+180° when the angle between the optical axis 30A of the liquid crystal compound 30 and the direction of arrow X reaches θ.

[0369] That is, the distance between the centers of two liquid crystal compounds 30 with equal angles relative to the arrow X direction in the arrow X direction is set as the length Λ of one period. Specifically, as... Figure 8As shown, the distance between the centers of the two liquid crystal compounds 30 whose arrow X direction is aligned with the direction of the optical axis 30A is defined as the length Λ of one period. In the following description, this length Λ of one period is also referred to as "one period Λ".

[0370] Furthermore, in the following description, in order to identify one period Λ in each optical anisotropy layer, one period Λ in the first optical anisotropy layer 26A will also be referred to as "Λ". A "Λ" refers to one period Λ in the second optical anisotropy layer 26B. B ".

[0371] In the optical element 10 of the present invention, the liquid crystal alignment pattern of the optical anisotropic layer changes in one direction by continuously rotating in the direction of arrow X, i.e., the direction of optical axis 30A, and repeats one cycle Λ.

[0372] As described above, in the optical anisotropy layer, the optical axis 30A of the liquid crystal compounds arranged along the Y direction forms an angle equal to that of the arrow X direction (a direction in which the optical axis of the liquid crystal compound 30 is rotated). The region in the Y direction where the liquid crystal compounds 30, whose optical axis 30A forms an angle equal to that of the arrow X direction, are disposed is designated as region R.

[0373] At this point, the value of the in-plane retardation (Re) in each region R is preferably half the wavelength, i.e., λ / 2. These in-plane retardations are calculated by multiplying the refractive index difference Δn associated with the refractive index anisotropy of region R by the thickness of the optical anisotropy layer. The refractive index difference caused by the refractive index anisotropy of region R in the optical anisotropy layer is defined as the 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 orthogonal to the slow axis. That is, the refractive index difference Δn caused by 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 plane of region R perpendicular to the optical axis 30A. In other words, the aforementioned refractive index difference Δn is equal to the refractive index difference of the liquid crystal compound.

[0374] If circularly polarized light is incident on such an optical anisotropy layer (first optical anisotropy layer 26A and second optical anisotropy layer 26B), the light is refracted and the direction of the circularly polarized light is reversed.

[0375] exist Figure 9 The effect is conceptually illustrated using the first optical anisotropic layer 26A as an example. Furthermore, in the first optical anisotropic layer 26A, the product of the refractive index difference of the liquid crystal compound and the thickness of the optical anisotropic layer is assumed to be λ / 2.

[0376] like Figure 9As shown, when the product of the refractive index difference of the liquid crystal compound in the first optical anisotropy layer 26a and the thickness of the optical anisotropy layer is λ / 2, if the incident light L1, which is left-handed circularly polarized light, is incident on the first optical anisotropy layer 26a, the incident light L1 passes through the first optical anisotropy layer 26a and is given a phase difference of 180°, thereby converting the transmitted light L2 into right-handed circularly polarized light.

[0377] On the other hand, such as Figure 10 Conceptually, when the product of the refractive index difference of the liquid crystal compound in the first optical anisotropic layer 26A and the thickness of the optical anisotropic layer is λ / 2, if the incident light L4 of right-hand circularly polarized light is incident on the first optical anisotropic layer 26A, the incident light L4 is given a phase difference of 180° by passing through the first optical anisotropic layer 26A, thereby being converted into transmitted light L5 of left-hand circularly polarized light.

[0378] In the first optical anisotropy layer 26A, the in-plane retardation value of the plurality of regions R is preferably half a wavelength, but the in-plane retardation Re(550) = Δn of the plurality of regions R of the first optical anisotropy layer 26A relative to incident light with a wavelength of 550 nm is... 550 ×d is preferably within the range specified in equation (1) below. Here, Δn 550 Let d be the refractive index difference caused by the anisotropy of the refractive index in region R when the wavelength of the incident light is 550 nm, and d be the thickness of the first optical anisotropy layer 26A.

[0379] 200nm≤Δn 550 ×d≤350nm……(1)

[0380] That is, if the in-plane delay Re(550) of multiple regions R of the first optical anisotropic layer 26A is Δn 550 If ×d satisfies equation (1), then a sufficient amount of circularly polarized light components of the light incident on the first optical anisotropic layer 26A can be converted into circularly polarized light traveling in a direction inclined to the positive or negative direction relative to the arrow X. In-plane delay Re(550)=Δn 550 ×d is more preferably 225nm≤Δn 550 ×d≤340nm, more preferably 250nm≤Δn 550 ×d≤330nm.

[0381] Furthermore, Equation (1) above represents the range of incident light with a wavelength of 550 nm, and the in-plane delay Re(λ) = Δn of multiple regions R of the optical anisotropy layer with a wavelength of λ nm is given by Equation (1). λ ×d is preferably set appropriately within the range specified in the following formula (1-2).

[0382] 0.7λnm≤Δn λ ×d≤1.3λnm……(1-2)

[0383] Furthermore, the in-plane delay values ​​of multiple regions R in the first optical anisotropy layer 26A can also be used outside the range of the above equation (1). Specifically, by setting it as Δn 550 ×d < 200nm or 350nm < Δn 550 ×d can be divided into light traveling in the same direction as the incident light and light traveling in a different direction than the incident light. When Δn 550 When ×d approaches 0nm or 550nm, the component of light traveling in the same direction as the incident light increases, while the component of light traveling in a different direction from the incident light decreases.

[0384] Furthermore, the in-plane delay Re(450) = Δn of region R of the first optical anisotropy layer 26A relative to incident light with a wavelength of 450 nm is... 450 ×d, the in-plane delay Re(550) = Δn of region R of the first optical anisotropy layer 26A relative to the incident light with a wavelength of 550nm. 550 ×d preferably satisfies the following equation (2). Here, Δn 450 Let be the refractive index difference caused by the anisotropy of the refractive index in region R when the wavelength of the incident light is 450 nm.

[0385] (Δn 450 ×d) / (Δn 550 ×d)<1.0……(2)

[0386] Equation (2) indicates that the liquid crystal compound 30 contained in the first optical anisotropic layer 26A has inverse dispersion. That is, by satisfying equation (2), the first optical anisotropic layer 26A can correspond to incident light with a wide wavelength.

[0387] Here, by changing one period Λ of the liquid crystal alignment pattern formed in the first optical anisotropy layer 26A, the refraction angles of transmitted light L2 and L5 can be adjusted. Specifically, the shorter the period Λ of the liquid crystal alignment pattern, the stronger the interference between the light passing through adjacent liquid crystal compounds 30, thus enabling the transmitted light L2 and L5 to be refracted more.

[0388] Furthermore, the refraction angles of transmitted light L2 and L5 relative to incident light L1 and L4 vary depending on the wavelengths of incident light L1 and L4 (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 incident light is red, green, or blue, red light exhibits the greatest refraction, while blue light exhibits the least.

[0389] Furthermore, by setting the rotation direction of the optical axis 30A of the liquid crystal compound 30 rotating in the direction of arrow X to the opposite direction, it is possible to set the direction of refraction of transmitted light to the opposite direction.

[0390] The optical anisotropy layer is composed of a cured layer of a liquid crystal composition containing a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound, and has a liquid crystal alignment pattern in which the optical axis of the rod-shaped liquid crystal compound or the optical axis of the disk-shaped liquid crystal compound is aligned as described above.

[0391] By forming an alignment film on the support 20, coating the alignment film with a liquid crystal composition, and curing it, an optically anisotropic layer composed of a cured layer of the liquid crystal composition can be obtained. Furthermore, while optically anisotropic layers function as a so-called λ / 2 sheet, the present invention includes a laminate integrally comprising the support 20 and the alignment film, which functions as a λ / 2 sheet.

[0392] Furthermore, the liquid crystal composition used to form the optical anisotropic layer contains rod-shaped liquid crystal compounds or disk-shaped liquid crystal compounds, and may further contain other components such as leveling agents, orientation control agents, polymerization initiators, and orientation aids.

[0393] Furthermore, the optical anisotropy layer preferably has a broadband wavelength relative to the incident light, and it is preferably constructed using a liquid crystal material with an inverse dispersion birefringence. It is also preferable to make the optical anisotropy layer substantially broadband relative to the incident light wavelength by imparting a twist component to the liquid crystal composition and by stacking different phase retardation layers. For example, a method for achieving a broadband patterned λ / 2 sheet in the optical anisotropy layer by stacking two liquid crystal layers with different twist directions is shown in Japanese Patent Application Publication No. 2014-089476, etc., and can preferably be used in this invention.

[0394] -Rod-shaped liquid crystal compounds-

[0395] As rod-shaped liquid crystal compounds, preferred materials include imine derivatives, azo derivatives, cyanobiphenyl derivatives, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane derivatives, cyano-substituted phenylpyrimidine derivatives, alkoxy-substituted phenylpyrimidine derivatives, phenyl dioxane derivatives, diphenylacetylene derivatives, and alkenylcyclohexylbenzyl nitrile derivatives. Not only low-molecular-weight liquid crystal molecules like those mentioned above can be used, but also high-molecular-weight liquid crystal molecules.

[0396] More preferably, the orientation of the rod-shaped liquid crystal compound is fixed by polymerization. As a polymerizable rod-shaped liquid crystal compound, it can be used in Makromol. Chem., Vol. 190, pp. 2255 (1989), Advanced Materials. Compounds described in 5 volumes, 107 pages (1993), U.S. Patent No. 4,683,327, U.S. Patent No. 5,622,648, U.S. Patent No. 5,770,107, International Publication No. 95 / 22586, International Publication No. 95 / 24455, International Publication No. 97 / 00600, International Publication No. 98 / 23580, International Publication No. 98 / 52905, Japanese Patent Application Publication No. 1-272,551, Japanese Patent Application Publication No. 6-16616, Japanese Patent Application Publication No. 7-110,469, Japanese Patent Application Publication No. 11-80081, and Japanese Patent Application Publication No. 2001-64627. Furthermore, as rod-shaped liquid crystal compounds, compounds described in Japanese Patent Application Publication No. 11-513019 and Japanese Patent Application Publication No. 2007-279688 are preferred.

[0397] -Disc-shaped liquid crystal compound-

[0398] As a disc-shaped liquid crystal compound, the disc-shaped liquid crystal compound described in Japanese Patent Application Publication No. 2007-108732 and Japanese Patent Application Publication No. 2010-244038 is preferred.

[0399] Furthermore, in the case where a disk-shaped liquid crystal compound is used in the optical anisotropy layer, the liquid crystal compound 30 stands upright in the thickness direction within the optical anisotropy layer, and the optical axis 30A derived from the liquid crystal compound is defined as an axis perpendicular to the disk surface, the so-called fast axis (see reference). Figure 20 ).

[0400] Wavelength-selective phase décor plate

[0401] The optical element 10 of the present invention has a wavelength selective phase difference plate 18G disposed between the first optical anisotropic component 12 and the second optical anisotropic component 14.

[0402] In the optical element of this invention, the wavelength-selective phase difference plate refers to a component that converts circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction.

[0403] In the optical element illustrated in the figure, the wavelength-selective phase retardation plate 18G selectively converts the circularly polarized light of green light into circularly polarized light with the opposite rotation direction, converts the right-hand circularly polarized light of green light into the left-hand circularly polarized light of green light, and converts the left-hand circularly polarized light of green light into the right-hand circularly polarized light of green light, while other light remains in the rotation direction and is transmitted (passes through unimpeded).

[0404] In other words, a wavelength-selective retardation plate refers to a plate that shifts the phase by π only in a specific wavelength region. Such a wavelength-selective retardation plate can also be called a λ / 2 plate that only acts in a specific wavelength region.

[0405] Regarding the wavelength-selective phase retardation plate (optical component), please refer to the above description.

[0406] [The function of optical components]

[0407] As described above, an optically anisotropic layer formed using a composition containing a liquid crystal compound, having a liquid crystal alignment pattern rotating in the direction of arrow X along the optical axis 30A, refracts circularly polarized light, but the angle of refraction varies depending on the wavelength of the light. Specifically, the longer the wavelength of the light, the larger the angle of refraction. Therefore, for example, in the case of incident red, green, and blue light, red light refracts the most, while blue light refracts the least.

[0408] Therefore, for example, in the light guide plate of AR glasses, when an optical element based on the optical anisotropy layer of the above-mentioned liquid crystal alignment pattern with the orientation rotation of the optical axis 30A is used as a light-incident light guide plate and a diffraction element emitted from the light guide plate, in a panchromatic image, the transmission directions of red light, green light and blue light are different, resulting in the observation of a so-called color-shifted image where the red image, green image and blue image are inconsistent.

[0409] Here, for example, as described in Bernard C. Kress et al., Towards the Ultimate Mixed Reality Experience: HoloLens Display Architecture Choices, SID 2017 DIGEST, pp. 127-131, a structure in which three light guide plates are stacked, corresponding to the red, green, and blue images respectively, can eliminate color shift. However, this structure results in the light guide plates becoming thicker and heavier overall, thus complicating the structure.

[0410] In contrast, in the optical element of the present invention, a plurality of optical anisotropic layers are arranged, and a wavelength selective retardation plate is provided between at least one pair of two adjacent optical anisotropic layers within the arranged optical anisotropic layers. Furthermore, the optical anisotropic layers have liquid crystal alignment patterns derived from the orientation of the optical axis of the liquid crystal compound rotating in one direction, and as long as one period of the liquid crystal alignment pattern of at least one optical anisotropic layer is different from that of the other optical anisotropic layers.

[0411] According to this optical element of the present invention, the wavelength dependence of the refraction angle of light can be significantly reduced, and light of different wavelengths can be refracted and transmitted / emitted in approximately the same direction. Therefore, by using the optical element of the present invention (as an example, optical element 32 described later) for example as a diffraction element that causes light to be incident on a light guide plate and / or causes light to be emitted from a light guide plate in AR glasses, red, green, and blue images can be transmitted through a single light guide plate without color shift, thereby displaying an appropriate image to the user.

[0412] The following is for reference. Figure 11 and Figure 12 The conceptual diagram provides a detailed explanation of the function of the optical element 10.

[0413] Furthermore, in the optical element of the present invention, essentially only the optical anisotropy layer and the wavelength-selective retardation plate exhibit optical effects. Therefore, in order to simplify the drawings and clearly illustrate the structure and effects, Figure 11 (and later) Figure 12 In the diagram, both the first optical anisotropic component 12 and the second optical anisotropic component 14 show only the first optical anisotropic layer 26A and the second optical anisotropic layer 26B, and the components are shown separately in the arrangement direction.

[0414] As described above, in the optical element 10, a wavelength-selective phase difference plate 18G is provided between the first optical anisotropy member 12 having a first optical anisotropy layer 26A and the second optical anisotropy member 14 having a second optical anisotropy layer 26B, which converts the rotation direction of the circularly polarized light of green light into the opposite direction.

[0415] As an example, optical element 10 targets circularly polarized blue light and circularly polarized green light, causing the incident light to refract and transmit in a predetermined direction. Furthermore, in Figure 11 In this case, the incident light is set as right-handed circularly polarized light. However, even if the incident light is left-handed circularly polarized light, the direction of refraction is simply reversed, and the effect is the same.

[0416] In optical element 10, if the right-handed circularly polarized light G of green light... R And right-handed circularly polarized blue light B R (refer to Figure 10 When incident light L4 is incident on the first optical anisotropy layer 26A, it is refracted at a predetermined angle relative to the incident direction in the direction opposite to arrow X, as described above, and converted into left-handed circularly polarized light G, which is green light. 1L and left-handed circularly polarized blue light B 1L (refer to Figure 10 Transmitted light L5).

[0417] Here, as mentioned above, the refraction angle caused by the first optical anisotropic layer 26A is larger in green light with a longer wavelength, therefore... Figure 12 As shown, the angle θ of the green light (G) relative to the angle of refraction of the incident light is... G1 Angle θ greater than that of blue light (B) B1 Furthermore, within one period Λ of the optical anisotropy layer, one period Λ of the first optical anisotropy layer 26A A It is shorter, so the refraction angle of each light is greater than that of the transmission second optical anisotropic layer 26B.

[0418] Left-handed circularly polarized light G of green light that has been transmitted through the first optical anisotropic layer 26A 1L and left-handed circularly polarized blue light B 1L It is then incident on a wavelength-selective phase difference plate 18G.

[0419] As described above, the wavelength-selective phase retardation plate 18G converts only the circularly polarized green light into circularly polarized light with the opposite rotation direction, while other light remains in its rotation direction and is transmitted (passes through unimpeded).

[0420] Therefore, if the left-handed circularly polarized light G of green light 1L and left-handed circularly polarized blue light B 1L If the light is incident on a wavelength-selective phase détragraph 18G and transmitted, then the left-handed circularly polarized blue light B... 1L Direct transmission. In contrast, the left-handed circularly polarized green light G... 1L Right-handed circularly polarized light G, converted into green light 1R .

[0421] Right-handed circularly polarized light G of green light transmitted through a wavelength-selective phase retardation plate 18G 1R and left-handed circularly polarized blue light B 1L It then enters the second optical anisotropic layer 26B.

[0422] Right-handed circularly polarized green light G incident on the second optical anisotropy layer 26B 1R and left-handed circularly polarized blue light B 1L Similarly, it is refracted, converting circularly polarized light into circularly polarized light with the opposite rotation direction, becoming the left-handed circularly polarized light G of green light. 2L And right-handed circularly polarized blue light B 2R And it was fired.

[0423] Here, the right-handed circularly polarized light G of green light incident on the second optical anisotropy layer 26B 1R Left-handed circularly polarized light B of blue light 1LThe circularly polarized light rotates in opposite directions. Furthermore, as described above, in the first optical anisotropy layer 26A and the second optical anisotropy layer 26B, the optical axis 30A of the liquid crystal compound 30 rotates in opposite directions.

[0424] Therefore, as Figure 11 and Figure 12 As shown, the left-handed circularly polarized light B of blue light 2L Further refracting in the direction opposite to arrow X, such as Figure 12 As shown on the left, relative to the incident light (right-hand circularly polarized light B of blue light) R ) by angle θ B2 Shoot it out.

[0425] In contrast, the right-handed circularly polarized light G of green light 1R The circularly polarized light, unlike blue light, rotates in the opposite direction. Therefore, as... Figure 12 As shown on the right, in the second optical anisotropy layer 26B, unlike the first optical anisotropy layer 26A, the light is refracted in the direction of arrow X to reflect it back. As a result, the left-handed circularly polarized green light G... 2L Relative to the incident light (right-hand circularly polarized light G of green light) R (at an angle smaller than the initial θ) G1 And with the left-handed circularly polarized light B of blue light 2L Angle θ B2 Almost the same angle θ G2 Shoot it out.

[0426] Thus, in the optical element 10 of the present invention, green light, which has a long wavelength and high refraction due to the optical anisotropy layer, is refracted in the first optical anisotropy layer 26A in the direction opposite to the arrow X, and then refracted in the second optical anisotropy layer 26B in the direction of the arrow X to be reflected back. In contrast, blue light, which has a short wavelength and low refraction due to the optical anisotropy layer, is refracted in the first optical anisotropy layer 26A and the second optical anisotropy layer 26B in the direction opposite to the arrow X.

[0427] That is, in optical element 10, depending on the magnitude of refraction caused by the optical anisotropy layer due to wavelength, longer wavelength light with greater refraction is refracted in the opposite direction and reflected back on the second refraction after the initial refraction. Conversely, shorter wavelength light with less refraction is refracted in the same direction on the second refraction as on the first refraction. Thus, the refraction angle θ of green light relative to the incident light can be adjusted. G2 and the angle of refraction θ of blue light relative to the incident light B2 It becomes an extremely close angle.

[0428] Therefore, according to the optical element 10 of the present invention, incident blue light and green light can be refracted at approximately the same angle and emitted in approximately the same direction.

[0429] As described above, the longer the wavelength of light, the greater the angle of the refracted light caused by the first optical anisotropic layer 26A and the second optical anisotropic layer 26B.

[0430] Furthermore, the shorter the period Λ of the optical axis 30A rotating 180° in the direction of arrow X in the liquid crystal alignment pattern, the larger the angle of the refracted light caused by the first optical anisotropic layer 26A and the second optical anisotropic layer 26B. In the optical element 10, as an example, such as... Figure 6 As shown, one period Λ of the liquid crystal alignment pattern in the first optical anisotropy layer 26A A Compared to one period Λ of the liquid crystal alignment pattern in the second optical anisotropy layer 26B B Short. That is, the first optical anisotropy layer 26A on the light incident side causes the light to refract more.

[0431] Therefore, by adjusting one period Λ of the liquid crystal alignment pattern for the wavelength of the light being targeted, it is possible to preferably make the emission direction of light of different wavelengths the same.

[0432] As shown in the example optical element 10, when two wavelength regions of light are considered, if the design wavelength of the longer wavelength light is set to λa and the design wavelength of the shorter wavelength light is set to λb (λa > λb), and one period of the liquid crystal alignment pattern in the first optical anisotropic layer is set to Λ1 and one period of the liquid crystal alignment pattern in the second optical anisotropic layer is set to Λ2, then when the following formula Λ2 = [(λa + λb) / (λa - λb)]Λ1 is satisfied, the emission directions of the light in the two wavelength regions can be made approximately the same. Furthermore, in this formula, either the first optical anisotropic layer 26A or the second optical anisotropic layer 26B can be designated as the first layer.

[0433] If this is taken into account, in the present invention, the optical element 10 that takes light of two wavelengths (wavelength regions) as its target preferably satisfies the following formula.

[0434] 0.6*{[(λa+λb) / (λa-λb)]Λ1}≤Λ2

[0435] ≤3.0*{[(λa+λb) / (λa-λb)]Λ1}

[0436] Therefore, the wavelength dependence of refraction can be minimized, so that the emission directions of light in the two wavelength regions are approximately the same.

[0437] Furthermore, in this invention, the optical element 10, which targets light of two wavelengths (wavelength regions), more preferably satisfies the following formula:

[0438] 0.7*{[(λa+λb) / (λa-λb)]Λ1}≤Λ2

[0439] ≤1.8*{[(λa+λb) / (λa-λb)]Λ1}

[0440] Further preferred options satisfy the following formula:

[0441] 0.8*{[(λa+λb) / (λa-λb)]Λ1}≤Λ2

[0442] ≤1.3*{[(λa+λb) / (λa-λb)]Λ1}

[0443] It is particularly preferred to satisfy the following formula.

[0444] 0.9*{[(λa+λb) / (λa-λb)]Λ1}≤Λ2

[0445] ≤1.15*{[(λa+λb) / (λa-λb)]Λ1}

[0446] <Second Method of Optical Elements>

[0447] The optical element 10 described above targets light in two wavelength regions (design wavelengths), namely green light and blue light. However, the optical element of the present invention is not limited to these two wavelength regions. It can also target light in three or more wavelength regions, so that the incident light is refracted and emitted.

[0448] Figure 13 One example is shown in the image.

[0449] in addition, Figure 13 The optical element 32 shown is mostly used in... Figure 6 The optical element 10 shown is the same part, so the same parts are marked with the same symbols. The following mainly describes the different parts.

[0450] Figure 13 In addition to the first optical anisotropy component 12, the second optical anisotropy component 14 and the wavelength selective phase retardation plate 18G of the aforementioned optical element 10, the optical element 32 also has a third optical anisotropy component 16 and a wavelength selective phase retardation plate 18R.

[0451] The third optical anisotropic component 16 has the same structure as the first optical anisotropic component 12, and includes a support 20, an alignment film 24C, and a third optical anisotropic layer 26C. The alignment film 24C and the third optical anisotropic layer 26C are the same as the aforementioned alignment film 24A and the first optical anisotropic layer 26A, except that one period Λ is different.

[0452] Furthermore, the wavelength-selective phase difference plate 18R selectively converts the circularly polarized light of red light into circularly polarized light with the opposite rotation direction, converts the right-hand circularly polarized light of red light into the left-hand circularly polarized light of red light, and converts the left-hand circularly polarized light of red light into the right-hand circularly polarized light of red light, while other light is directly transmitted (passes through without obstruction).

[0453] In optical element 32, in the first optical anisotropy layer 26A and the third optical anisotropy layer 26C, the rotation direction of the optical axis 30A of the liquid crystal compound 30 along the direction of arrow X is equal, and in the second optical anisotropy layer 26B, the rotation direction of the optical axis 30A of the liquid crystal compound 30 along the direction of arrow X is opposite to that of the other two optical anisotropy layers.

[0454] Furthermore, in the optical element 32, within one period Λ of the arrow X direction in which the optical axis 30A of the liquid crystal compound 30 rotates 180° in the liquid crystal alignment pattern, one period Λ of the first optical anisotropy layer 26A... A The shortest, one period Λ of the second optical anisotropy layer 26B B The optical element 32 has the first optical anisotropy component 12 side as the light incident side. That is, in the optical element 32, the first optical anisotropy layer 26A on the light incident side maximizes the refraction of light.

[0455] Furthermore, an optical element 32 is provided with a wavelength-selective retardation plate 18R that selectively converts the rotation direction of circularly polarized light of red light between the first optical anisotropy member 12 (first optical anisotropy layer 26A) and the second optical anisotropy member 14 (second optical anisotropy layer 26B). Additionally, an optical element 32 is provided with a wavelength-selective retardation plate 18G that selectively converts the rotation direction of circularly polarized light of green light between the second optical anisotropy member 14 and the third optical anisotropy member 16 (third optical anisotropy layer 26C).

[0456] The following is for reference. Figure 14 and Figure 15 The function of optical element 32 will be explained in detail.

[0457] As an example, optical element 10 targets circularly polarized light of red, green, and blue light, causing the incident light to refract and transmit in a predetermined direction. Furthermore, similar to the above... Figure 11 Similarly, in Figure 14 In this case, the incident light is set as right-handed circularly polarized light. However, even if the incident light is left-handed circularly polarized light, the direction of refraction is simply reversed, and the effect is the same.

[0458] In optical element 10, if the right-handed circularly polarized light R of red light... R Right-handed circularly polarized green light G R And right-handed circularly polarized blue light B R (refer to Figure 10 When incident light L4 is incident on the first optical anisotropy layer 26A, it is refracted at a predetermined angle relative to the incident direction in the direction opposite to arrow X, as described above, and converted into left-handed circularly polarized light R (red light). 1L Left-handed circularly polarized green light G 1L and left-handed circularly polarized blue light B 1L (refer to Figure 10 Transmitted light L5).

[0459] Here, as mentioned above, regarding the refraction angle caused by the first optical anisotropic layer 26A, the longest wavelength red light has the largest refraction angle, and the shortest wavelength blue light has the smallest. Therefore, as Figure 15 As shown, in the angle of refraction relative to the incident light, the angle θ of the red light (R) is... R1 The angle θ of the maximum green light (G) G1 At the center, the angle θ of the blue light (B) B1 Minimum. Additionally, regarding one period Λ of the optical anisotropy layer, one period Λ of the first optical anisotropy layer 26A... A The shortest, therefore the refraction angle of each light is the largest when transmitting through the first optical anisotropic layer 26A.

[0460] Left-handed circularly polarized light R, which has been transmitted through the first optical anisotropy layer 26A. 1L Left-handed circularly polarized green light G 1L and left-handed circularly polarized blue light B 1L It is then incident on the wavelength-selective phase difference plate 18R.

[0461] As described above, the wavelength-selective phase difference plate 18R converts only the circularly polarized red light into circularly polarized light with the opposite rotation direction, while other light is transmitted directly (passes through without obstruction).

[0462] Therefore, if the left-handed circularly polarized light R of red light 1L Left-handed circularly polarized green light G 1L and left-handed circularly polarized blue light B 1L When incident on and transmitted through a wavelength-selective phase difference plate 18R, the left-handed circularly polarized green light G... 1Land left-handed circularly polarized blue light B 1L Direct transmission. In contrast, the left-handed circularly polarized light R of red light... 1L Right-handed circularly polarized light R, converted into red light 1R .

[0463] Right-handed circularly polarized light R of red light transmitted through wavelength-selective phase difference plate 18R 1R Left-handed circularly polarized green light G 1L and left-handed circularly polarized blue light B 1L It then enters the second optical anisotropic layer 26B.

[0464] Right-handed circularly polarized light R of red light incident on the second optical anisotropy layer 26B 1R Left-handed circularly polarized green light G 1L and left-handed circularly polarized blue light B 1L Similarly, it is refracted, converting circularly polarized light into circularly polarized light with the opposite rotation direction, becoming the left-handed circularly polarized light R of red light. 2L Right-handed circularly polarized green light G 2R And right-handed circularly polarized blue light B 2R And it was fired.

[0465] Here, the green and blue light incident on the second optical anisotropy layer 26B are both left-handed circularly polarized light. In contrast, the red light incident on the second optical anisotropy layer 26B is right-handed circularly polarized light, whose direction of circular polarization has been converted by the wavelength-selective phase retardation plate 18R, and whose direction of circular polarization is different from that of the green and blue light.

[0466] Furthermore, as described above, in the first optical anisotropy layer 26A and the second optical anisotropy layer 26B, the rotation directions of the optical axis 30A of the liquid crystal compound 30 are opposite.

[0467] Therefore, as Figure 14 and Figure 15 As shown, the left-handed circularly polarized light G of green light incident on the second optical anisotropic layer 26B 2L and left-handed circularly polarized blue light B 2L Further refracting in the direction opposite to arrow X, such as Figure 15 As shown, relative to the incident light (right-hand circularly polarized light G of green light) R And right-handed circularly polarized blue light B R ), with angle θ G2 and angle θ B2 Shoot it out.

[0468] In contrast, such as Figure 15As shown on the right, the right-hand circularly polarized light R, which is the opposite direction of the circularly polarized light incident on the second optical anisotropic layer 26B, is a red light. 1R The light emitted from the second optical anisotropy layer 26B is refracted in the direction of arrow X, opposite to the first optical anisotropy layer 26A, so that it is reflected back. As a result, the left-handed circularly polarized light R of the red light emitted from the second optical anisotropy layer 26B... 2L Relative to the incident light (right-hand circularly polarized light R of red light) R (with an angle less than angle θ) R1 Angle θ R2 Shoot it out.

[0469] In addition, regarding one period Λ of the optical anisotropy layer, one period Λ of the second optical anisotropy layer 26B B The longest, therefore the refraction angle of each light is the smallest when transmitting through the second optical anisotropic layer 26B.

[0470] Left-handed circularly polarized light R, which has been transmitted through the second optical anisotropy layer 26B. 2L Right-handed circularly polarized green light G 2R And right-handed circularly polarized blue light B 2R It is then incident on a wavelength-selective phase difference plate 18G.

[0471] As described above, the wavelength-selective phase détachometer 18G converts only the circularly polarized green light into circularly polarized light with the opposite rotation direction, while other light is transmitted directly.

[0472] Therefore, if the left-handed circularly polarized light R of red light 2L Right-handed circularly polarized green light G 2R And right-handed circularly polarized blue light B 2R If the light is incident on and transmitted through a wavelength-selective phase difference plate 18G, then the left-handed circularly polarized light R of the red light... 2L And right-handed circularly polarized blue light B 2R Direct transmission. In contrast, the right-handed circularly polarized green light G... 2R Left-handed circularly polarized light G, converted into green light 2L .

[0473] Left-handed circularly polarized light R of red light transmitted through a wavelength-selective phase retardation plate of 18G 2L Left-handed circularly polarized green light G 2L And right-handed circularly polarized blue light B 2R It then enters the third optical anisotropy layer 26C.

[0474] Left-handed circularly polarized red light incident on the third optical anisotropy layer 26C 2L Left-handed circularly polarized green light G 2L And right-handed circularly polarized blue light B2R Similarly, it is refracted, converting circularly polarized light into circularly polarized light with the opposite direction of rotation, becoming right-handed circularly polarized light R of red light. 3R Right-handed circularly polarized green light G 3R and left-handed circularly polarized blue light B 3L And it was fired.

[0475] Here, the blue light incident on the third optical anisotropy layer 26C is right-handed circularly polarized blue light B. 2R Furthermore, the red light first undergoes a wavelength-selective phase difference plate 18R to convert the direction of the circularly polarized light. Therefore, the red light incident on the third optical anisotropy layer 26C is left-handed circularly polarized light R, with a direction different from that of the blue light. 2L Furthermore, the green light incident on the third optical anisotropy layer 26C is a left-handed circularly polarized light G of green light whose direction of circular polarization has been converted by the wavelength-selective phase retardation plate 18G. 2L .

[0476] That is, the light incident on the third optical anisotropy layer 26C is: blue light is right-handed circularly polarized light, and red and green light are left-handed circularly polarized light whose direction has been converted by a wavelength-selective phase difference plate.

[0477] Furthermore, as described above, in the second optical anisotropy layer 26B and the third optical anisotropy layer 26C, the rotation directions of the optical axis 30A of the liquid crystal compound 30 are opposite.

[0478] Therefore, as Figure 14 and Figure 15 As shown, the right-handed circularly polarized light B of blue light incident on the third optical anisotropy layer 26C. 2R Further refracting in the direction opposite to arrow X, such as Figure 15 As shown, relative to the incident light (right-hand circularly polarized light B of blue light) R ) by angle θ B3 Shoot it out.

[0479] In contrast, when the direction of circularly polarized light is opposite to that of red light, the left-handed circularly polarized light R... 2L When incident on the third optical anisotropy layer 26C, it is further refracted in a manner returning to the direction of arrow X. As a result, the right-handed circularly polarized light R emitted from the third optical anisotropy layer 26C... 3R Relative to the incident light (right-hand circularly polarized light R of red light) R (The angle is smaller than the previous angle θ) R2 Angle θ R3 Shoot it out.

[0480] Similarly, if the circularly polarized light is the opposite of the blue light, then the left-handed circularly polarized light G of the green light is...2L When incident on the third optical anisotropic layer 26C, then as Figure 14 As shown in the center, contrary to the previous method, it is refracted in a manner returning to arrow X. As a result, the right-handed circularly polarized light G emitted from the third optical anisotropy layer 26C... 3R Relative to the incident light (right-hand circularly polarized light G of green light) R (with an angle less than angle θ) G2 Angle θ G3 Shoot it out.

[0481] That is, in optical element 32, the red light with the longest wavelength and the largest refraction caused by the optical anisotropy layer is refracted twice by the second optical anisotropy layer 26B and the third optical anisotropy layer 26C in the opposite direction of arrow X after being refracted by the first optical anisotropy layer 26A in the opposite direction of arrow X.

[0482] Furthermore, the second longest wavelength green light, which is refracted by the optical anisotropy layer, is refracted in the opposite direction to arrow X by the first optical anisotropy layer 26A and the second optical anisotropy layer 26B, and then refracted once in the opposite direction to arrow X by the third optical anisotropy layer 26C.

[0483] Furthermore, the blue light with the shortest wavelength and the least refraction caused by the optical anisotropy layer is refracted three times in the opposite direction to arrow X by the first optical anisotropy layer 26A, the second optical anisotropy layer 26B, and the third optical anisotropy layer 26C.

[0484] Thus, the optical element 32 of the present invention first refracts all light in the same direction to a large extent, and then, based on the magnitude of refraction caused by the optical anisotropy layer according to the wavelength, refracts the longest wavelength light the most times so that it returns in the opposite direction to the initial refraction. As the wavelength decreases, the number of refractions returning in the opposite direction to the initial refraction is reduced, and the shortest wavelength light minimizes the number of refractions returning in the opposite direction to the initial refraction. Therefore, the refraction angle θ of red light relative to the incident light can be minimized. R3 The angle of refraction θ of green light relative to the incident light G3 and the angle of refraction θ of blue light relative to the incident light B3 It becomes an extremely close angle.

[0485] Therefore, according to the optical element 32 of the present invention, incident red light, blue light and green light can be refracted at approximately the same angle and emitted in approximately the same direction.

[0486] As shown in the example optical element 32, when taking light from three wavelength regions as the target, the design wavelength of the longest wavelength light is set as λa, the design wavelength of the middle wavelength light is set as λb, and the design wavelength of the shortest wavelength light is set as λc (λa>λb>λc). When one period of the liquid crystal alignment pattern in the first optical anisotropic layer is set as Λ1, one period of the liquid crystal alignment pattern in the second optical anisotropic layer is set as Λ2, and one period of the liquid crystal alignment pattern in the third optical anisotropic layer is set as Λ3, if the following two equations are satisfied, Λ2=[(λa+λc)λb / (λa-λb)λc]Λ1 and Λ3=[(λa+λc)λb / (λb-λc)λa]Λ1, the emission directions of light from the two wavelength regions can be made approximately the same. In addition, in this formula, either the first optical anisotropic layer 26A or the third optical anisotropic layer 26C can be designated as the first layer.

[0487] Taking this into account, in the present invention, among the optical elements 32 that take light of three wavelengths (wavelength regions) as objects, it is preferable to satisfy at least one of the following two formulas, and more preferably to satisfy both.

[0488] 0.6*{[(λa+λc)λb / (λa-λb)λc]Λ1}≤Λ2

[0489] ≤3.0*{[(λa+λc)λb / (λa-λb)λc]Λ1}

[0490] 0.6*{[(λa+λc)λb / (λb-λc)λa]Λ1}≤Λ3

[0491] ≤3.0*{[(λa+λc)λb / (λb-λc)λa]Λ1}

[0492] Therefore, the wavelength dependence of refraction can be minimized, so that the emission directions of light in the two wavelength regions are approximately the same.

[0493] Furthermore, in this invention, the optical element 32, which targets light of three wavelengths (wavelength regions), more preferably satisfies the following two formulas.

[0494] 0.7*{[(λa+λc)λb / (λa-λb)λc]Λ1}≤Λ2

[0495] ≤1.8*{[(λa+λc)λb / (λa-λb)λc]Λ1}

[0496] 0.7*{[(λa+λc)λb / (λb-λc)λa]Λ1}≤Λ3

[0497] ≤1.8*{[(λa+λc)λb / (λb-λc)λa]Λ1}

[0498] Further optimization is to satisfy the following two equations,

[0499] 0.8*{[(λa+λc)λb / (λa-λb)λc]Λ1}≤Λ2

[0500] ≤1.3*{[(λa+λc)λb / (λa-λb)λc]Λ1}

[0501] 0.8*{[(λa+λc)λb / (λb-λc)λa]Λ1}≤Λ3

[0502] ≤1.3*{[(λa+λc)λb / (λb-λc)λa]Λ1}

[0503] It is particularly preferred to satisfy the following two formulas.

[0504] 0.9*{[(λa+λc)λb / (λa-λb)λc]Λ1}≤Λ2

[0505] ≤1.15*{[(λa+λc)λb / (λa-λb)λc]Λ1}

[0506] 0.9*{[(λa+λc)λb / (λb-λc)λa]Λ1}≤Λ3

[0507] ≤1.15*{[(λa+λc)λb / (λb-λc)λa]Λ1}

[0508] In the optical element of the present invention, as described above, a plurality of optical anisotropic layers are arranged. Depending on the wavelength of the light, longer wavelength light, which is refracted more by the optical anisotropic layers, is refracted more times in the direction opposite to that of the initial optical anisotropic layer. This enables light of different wavelengths to be refracted at approximately the same angle and emitted in approximately the same direction.

[0509] Therefore, in the optical element of the present invention, when multiple wavelength conversion phase difference layers are provided, and with Figure 13 and Figure 14 Similarly, in the optical element 32 shown, the wavelength-selective retardation plate preferably converts circularly polarized light into light with an opposite rotational direction in the arrangement direction of the optical anisotropic layers, with the wavelength region gradually becoming shorter.

[0510] Furthermore, in the optical element of the present invention, the refraction caused by the initial optical anisotropy layer is increased, and then gradually refracted in the same direction and gradually refracted in the opposite direction. This makes it easier to control the refraction of each light and to make the refraction of each light more uniform. Taking this into account, it is consistent with... Figure 13 and Figure 14Similarly, in the optical element 32 shown, the optical anisotropy layer preferably has the shortest period Λ of the liquid crystal alignment pattern of the optical anisotropy layer located at the very end of the alignment direction. That is, it is preferable to maximize the refraction caused by the optical anisotropy layer located at the very end of the alignment direction.

[0511] Furthermore, in the optical element of the present invention, one period Λ of the liquid crystal alignment pattern of the optical anisotropy layer can be a structure that gradually increases in the alignment direction of the optical anisotropy layer. Or, as... Figure 13 and Figure 14 As shown in the optical element 32, a structure is formed where an optical anisotropy layer with a period Λ between the optical anisotropy layer with the largest period Λ of the liquid crystal alignment pattern and the optical anisotropy layer with the smallest period Λ of the liquid crystal alignment pattern is provided. The variation of the period Λ of the liquid crystal alignment pattern in the optical anisotropy layers can be irregular in the arrangement direction of the optical anisotropy layers. That is, in the optical element of the present invention, the period Λ of the liquid crystal alignment pattern of each optical anisotropy layer can be appropriately set according to the wavelength of light and the refractive index caused by the optical anisotropy layer.

[0512] In the optical element of the present invention, when multiple wavelength conversion phase difference layers are provided, it is essentially the same as... Figure 13 and Figure 14 Similarly, in the optical element 32 shown, optical anisotropic layers and wavelength conversion phase difference layers are arranged alternately. In this case, the number of wavelength conversion phase difference layers is preferably one less than the number of optical anisotropic layers.

[0513] However, the present invention is not limited thereto. For example, it may also be configured to arrange multiple optical anisotropic layers in a continuous manner so that light refracted by the multiple optical anisotropic layers is incident on the wavelength conversion phase difference layer.

[0514] Furthermore, multiple wavelength conversion phase difference layers can be disposed between two optical anisotropic layers. However, when multiple wavelength conversion phase difference layers that convert circularly polarized light in the same wavelength region into circularly polarized light with opposite rotation directions are disposed between two optical anisotropic layers, the number of such layers is preferably set to an odd number.

[0515] In the optical element of the present invention, there may be an optical anisotropy layer with one period Λ of the liquid crystal alignment pattern.

[0516] However, from the viewpoint that it is easy to make the refraction of light in multiple wavelength regions uniform, i.e., the emission angle is uniform, it is preferable that the liquid crystal alignment pattern is different in one period Λ in all optical anisotropy layers.

[0517] In the optical element of the present invention, there is no limitation on one period Λ in the orientation pattern of the optical anisotropic layer, and it can be appropriately set according to the purpose of the optical element.

[0518] In the optical element of the present invention, a wavelength-selective retardation plate may be provided to selectively convert circularly polarized light of the shortest wavelength design wavelength into circularly polarized light of the opposite rotation direction. For example, a third wavelength-selective retardation plate B that selectively converts circularly polarized blue light into circularly polarized light of the opposite rotation direction may be disposed after the third optical anisotropy layer 26C (downstream of the light travel direction).

[0519] As described above, the third wavelength selective phase difference plate B converts only the circularly polarized blue light into circularly polarized light with the opposite rotation direction, while other light is transmitted directly.

[0520] Therefore, if the right-handed circularly polarized light R of red light 3R Right-handed circularly polarized green light G 3R and left-handed circularly polarized blue light B 3L If the light is incident on and transmitted through the third wavelength selective phase difference plate B, then the right-hand circularly polarized light R of the red light will... 3R and right-handed circularly polarized green light G 3R Direct transmission. In contrast, left-handed circularly polarized blue light B... 3L Right-handed circularly polarized light B, converted into blue light 3R .

[0521] Therefore, it is possible to set the circularly polarized light emitted from the optical element—blue, green, and red—to be circularly polarized light with the same rotation direction.

[0522] Here, as an example, the optical elements of the present invention are preferably used in AR glasses as diffractive elements that refract light displayed on the display and guide it to the light guide plate, and as diffractive elements that refract light propagating from the light guide plate and emit it from the light guide plate to a position based on the user's viewing position. In particular, the optical element 32, which can correspond to a panchromatic image, can preferably be used as a diffractive element in AR glasses.

[0523] At this point, in order to achieve total internal reflection of the light through the light guide plate, the light needs to be refracted at a relatively large angle relative to the incident light and guided into the light guide plate. Furthermore, in order to reliably emit the light propagating in the light guide plate, the light also needs to be refracted at a relatively large angle relative to the incident light.

[0524] Furthermore, as described above, regarding the light transmission angle caused by the optical anisotropic layer, the angle of the transmitted light relative to the incident light can be increased by shortening one period Λ in the liquid crystal alignment pattern.

[0525] When this is taken into account, one period Λ in the liquid crystal alignment pattern of the optical anisotropy layer is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 3 μm or less.

[0526] Furthermore, considering factors such as the precision of the liquid crystal alignment pattern, it is preferable to set one period Λ in the liquid crystal alignment pattern of the optical anisotropy layer to be 0.1 μm or more.

[0527] exist Figures 9-15 In the optical element shown, the optical axis 30A of the liquid crystal compound 30 in the liquid crystal alignment pattern of the optical anisotropy layer rotates continuously only in the direction of arrow X.

[0528] However, the present invention is not limited thereto. Various structures can be used as long as the optical axis 30A of the liquid crystal compound 30 rotates continuously in one direction in the optical anisotropic layer.

[0529] As an example, liquid optical anisotropy layer 34 is shown, wherein, for example... Figure 17 As conceptually shown in the top view, the liquid crystal alignment pattern is a concentric circle pattern that changes in one direction from the inside to the outside as the orientation of the optical axis of the liquid crystal compound 30 rotates continuously. In other words, Figure 17 The liquid crystal alignment pattern of the optical anisotropy layer 34 shown is a liquid crystal alignment pattern that is radially arranged from the center of the optical anisotropy layer 34, where the orientation of the optical axis of the liquid crystal compound 30 changes as it rotates continuously.

[0530] In addition, Figure 17 In, with Figure 9 Similarly, only the liquid crystal compound 30 on the surface of the alignment film is shown, but in the optical anisotropy layer 34, as... Figure 7 As shown, the structure has a liquid crystal compound 30 stacked from the surface of the alignment film, as described above.

[0531] In addition, Figure 17 In the illustration, only one optical anisotropic layer 34 is shown. However, as described above, the optical element of the present invention has multiple optical anisotropic layers, and a wavelength-selective retardation plate is present between at least one pair of two optical anisotropic layers. Therefore, even in the case of optical anisotropic layers with such concentric liquid crystal alignment patterns, as an example, such as Figure 13 Like the optical element 32 shown, it also has a structure in which a first optical anisotropy layer, a wavelength-selective phase retardation plate for converting red light into circularly polarized light, a second optical anisotropy layer, a wavelength-selective phase retardation plate for converting green light into circularly polarized light, and a third optical anisotropy layer are arranged.

[0532] exist Figure 17In the optical anisotropic layer 34 shown, the optical axis of the liquid crystal compound 30 (not shown) is the length direction of the liquid crystal compound 30.

[0533] In the optical anisotropy layer 34, the orientation of the optical axis of the liquid crystal compound 30 changes along multiple directions from the center of the optical anisotropy layer 34 outward, such as the direction indicated by arrow A1, the direction indicated by arrow A2, the direction indicated by arrow A3, etc., as it rotates continuously.

[0534] Circularly polarized light incident on the optically anisotropic layer 34 having the liquid crystal alignment pattern experiences changes in absolute phase in different local regions of the liquid crystal compound 30 with different optical axis orientations. The amount of change in each absolute phase varies depending on the orientation of the optical axis of the liquid crystal compound 30 on which the circularly polarized light is incident.

[0535] The optical anisotropy layer 34, which has a concentric liquid crystal alignment pattern, i.e., a liquid crystal alignment pattern in which the optical axis rotates radially, can transmit incident light as diverging or converging light according to the rotation direction of the optical axis of the liquid crystal compound 30 and the direction of the incident circularly polarized light.

[0536] That is, by setting the liquid crystal alignment pattern of the optical anisotropic layer to a concentric circle, the optical element of the present invention can perform functions, for example, as a convex lens or a concave lens.

[0537] Here, when the liquid crystal alignment pattern of the optical anisotropic layer is set as a concentric circle and the optical element functions as a convex lens, it is preferable that one cycle Λ in which the optical axis rotates 180° in the liquid crystal alignment pattern gradually shortens from the center of the optical anisotropic layer 34 toward the direction of continuous rotation of the optical axis in the outward direction.

[0538] As described above, the shorter the period Λ in the liquid crystal alignment pattern, the larger the refraction angle of light relative to the incident direction. Therefore, by gradually shortening the period Λ in the liquid crystal alignment pattern in a direction that rotates continuously from the center of the optical anisotropic layer 34 toward the optical axis, the light focusing force caused by the optical anisotropic layer 34 can be further improved, and the performance as a convex lens can be improved.

[0539] Furthermore, in this invention, for example, when it is configured as a concave lens, depending on the application of the optical element, it is preferable to rotate the optical axis in the liquid crystal alignment pattern for one cycle Λ of 180° from the center of the optical anisotropy layer 34, so that the optical axis rotates in the opposite direction to the direction of continuous rotation and gradually shortens in the outward direction of one direction.

[0540] As described above, the shorter the period Λ in the liquid crystal alignment pattern, the larger the refraction angle of light relative to the incident direction. Therefore, by gradually shortening the period Λ in the liquid crystal alignment pattern in a direction that rotates continuously from the center of the optical anisotropic layer 34 toward the optical axis, the light divergence caused by the optical anisotropic layer 34 can be further improved, and the performance as a concave lens can be improved.

[0541] Furthermore, in this invention, it is preferable, for example, to reverse the rotation direction of the incident circularly polarized light by setting the optical element as a concave lens.

[0542] In this invention, when the optical element functions as a convex or concave lens, it is preferable to satisfy the following formula.

[0543] Φ(r)=(π / λ)[(r 2 +f 2 ) 1 / 2 -f]

[0544] Here, r is the distance from the center of the concentric circles, given by the following formula: r = (x 2 +y 2 ) 1 / 2 Let x and y represent the positions within the plane, and (x, y) = (0, 0) represent the center of the concentric circles. Φ(r) represents the angle of the optical axis at a distance r from the center, λ represents the wavelength, and f represents the designed focal length.

[0545] Alternatively, in this invention, one period Λ in the concentric liquid crystal alignment pattern can be made to gradually lengthen in the outward direction of a direction in which the center of the optical anisotropic layer 34 rotates continuously toward the optical axis.

[0546] Furthermore, depending on the intended use of the optical element and the desired distribution of light intensity in the transmitted light, a structure can be used in which a period Λ is gradually changed in one direction without continuous rotation toward the optical axis, while a region with a different period Λ is locally present in one direction with continuous rotation toward the optical axis.

[0547] Furthermore, the optical element of the present invention can have an optically anisotropic layer with a period Λ uniform across the entire surface and an optically anisotropic layer with regions different across a period Λ. This will be explained later. Figure 6 As shown, the same applies to structures where the optical axis rotates continuously in only one direction.

[0548] exist Figure 18 The present invention conceptually illustrates an example of an exposure apparatus for forming such concentric circle orientation patterns on orientation films (e.g., orientation films 24A, 24B, and 24C).

[0549] The exposure apparatus 80 includes: a light source 84 with a laser 82, a polarization beam splitter 86 that splits the laser beam M from the laser 82 into S-polarized MS and P-polarized MP, a reflector 90A disposed in the optical path of P-polarized MP and a reflector 90B disposed in the optical path of S-polarized MS, a lens 92 disposed in the optical path of S-polarized MS, a polarization beam splitter 94, and a λ / 4 plate 96.

[0550] The P-polarized light MP, split by polarization beam splitter 86, is reflected by mirror 90A and incident on polarization beam splitter 94. On the other hand, the S-polarized light MS, split by polarization beam splitter 86, is reflected by mirror 90B, converges through lens 92, and incident on polarization beam splitter 94.

[0551] P-polarized light MP and S-polarized light MS are combined by polarization beam splitter 94 and passed through λ / 4 plate 96 to become right-hand circularly polarized light and left-hand circularly polarized light corresponding to the polarization direction, so as to be incident on the alignment film 24 on the support 20.

[0552] Here, through the interference of right-handed and left-handed circularly polarized light, the polarization state of the light illuminating the alignment film 24 changes periodically in the form of interference fringes. Since the crossing angle between the left-handed and right-handed circularly polarized light changes from the inside to the outside of the concentric circles, an exposure pattern in which the pitch changes from the inside to the outside can be obtained. Thus, a concentric circular alignment pattern in which the alignment state changes periodically can be obtained in the alignment film 24.

[0553] In this exposure apparatus 80, one cycle Λ of the liquid crystal alignment pattern in which the optical axis of the liquid crystal compound 30 rotates 180° continuously in 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.

[0554] Furthermore, by adjusting the refractive power of lens 92 (F-value of lens 92), the length Λ of one cycle of the liquid crystal alignment pattern can be changed in one direction of continuous rotation of the optical axis.

[0555] Specifically, by adjusting the diffusion angle of the light diffused through lens 92 in a direction that allows continuous rotation of the optical axis, the length Λ of one period of the liquid crystal alignment pattern can be changed. More specifically, if the refractive power of lens 92 is reduced, the light becomes closer to parallel, and therefore the length Λ of one period of the liquid crystal alignment pattern gradually shortens from the inside to the outside, and the F-value increases. Conversely, if the refractive power of lens 92 is increased, the length Λ of one period of the liquid crystal alignment pattern shortens sharply from the inside to the outside, and the F-value decreases.

[0556] Thus, the structure that changes the optical axis rotation by 180° in one direction of continuous rotation of the optical axis for one cycle Λ can also be used in... Figures 6-15 The structure of the liquid crystal compound 30 shown changes when the optical axis 30A is rotated continuously in only one direction, the direction of arrow X.

[0557] For example, by gradually shortening one period Λ of the liquid crystal alignment pattern towards the direction of arrow X, an optical element that transmits light in a converging manner can be obtained. Furthermore, by reversing the direction of the 180° rotation of the optical axis in the liquid crystal alignment pattern, an optical element that transmits light in a manner that diffuses only in the direction of arrow X can be obtained. Additionally, even if the rotation direction of the incident circularly polarized light is reversed, an optical element that transmits light in a manner that diffuses only in the direction of arrow X can be obtained.

[0558] Furthermore, depending on the desired light distribution in the transmitted light and the intended use of the optical element, a structure can be used where a period Λ is not gradually changed in the direction of arrow X, but rather a region is locally different by a period Λ in the direction of arrow X. For example, as a method of locally changing a period Λ, a method of patterning the photo-alignment film by scanning and exposing the laser beam while arbitrarily changing the polarization direction of the converged laser beam can be used.

[0559] The optical element of the present invention can be used in various applications such as optical path changing components, light converging elements, light diffusing elements and diffraction elements in optical devices, and light transmitting in directions different from the incident direction.

[0560] As a preferred example, such as Figure 19 The diagram conceptually illustrates a method of using the light guide plate as a diffraction element, wherein, by being separately positioned from the light guide plate 42, light (projected image) illuminated by the display 40 is directed into the light guide plate 42 at an angle sufficient to achieve total internal reflection in the aforementioned AR glasses, and the light propagating in the light guide plate 42 is emitted from the light guide plate 42 to the viewing position of the user U based on the AR glasses. Furthermore, in Figure 19 In the image, an example corresponding to the panchromatic image is shown. Figure 13 The optical element 32 shown can also be preferably used, for example, when displaying a dual-color image with AR glasses. Figure 6 The optical element 10 shown.

[0561] As described above, in the optical element of the present invention, the angular dependence of the refraction angle during transmission is small, thus enabling the red, green, and blue light emitted by the display 40 to be refracted in the same direction. Therefore, even if the red, green, and blue images are transmitted through a single light guide plate 42, a full-color image without color shift can be emitted from the light guide plate to the viewing position of the user U based on the AR glasses. Therefore, according to the optical element of the present invention using the optical element of the present invention, the light guide plate of the AR glasses can be made thinner and lighter overall, thereby simplifying the structure of the AR glasses.

[0562] In addition, such as Figure 19 As shown, the light guide element of the present invention is not limited to the structure of two optical elements of the present invention that are separated from each other on the light guide plate 42. It can also be a structure in which only one optical element of the present invention is provided on the light guide plate in order to guide light onto the light guide plate 42 or to guide light out of the light guide plate 42.

[0563] In the above examples, the optical element of the present invention is used in an optical element having two or three optical anisotropic layers that transmits and refracts light of two colors, namely green and blue, or three colors, namely red, green and blue. However, the present invention is not limited to this and various structures can be used.

[0564] For example, the optical element of the present invention can also have the following structure: with Figure 13 Similarly, it has 3 layers of optical anisotropic layers and 2 layers of wavelength-selective retardation plates, and transmits and refracts two colors selected from red, green, and blue light, and infrared or ultraviolet light. Alternatively, the optical element of the present invention can have the following structure: having 4 or 5 (or 6 or more) layers of optical anisotropic layers and 3 or 4 layers (the number of optical anisotropic layers minus 1 layer) of wavelength-selective retardation plates, and in addition to transmitting and refracting red, green, and blue light, also transmitting and refracting infrared and / or ultraviolet light. Alternatively, the optical element of the present invention can also have the following structure: with... Figure 6 Similarly, it has a structure with two optical anisotropic layers and one wavelength-selective retardation plate, which transmits and refracts red and blue light or red and green light; or a structure that transmits and refracts one color selected from red, green and blue light and infrared or ultraviolet light. Alternatively, it can be a structure that refracts and transmits infrared and / or ultraviolet light.

[0565] Example

[0566] The present invention will now be described in further detail with reference to embodiments.

[0567] The materials, quantities, proportions, processing contents, and processing steps shown in the following embodiments can be appropriately modified as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as limited by the embodiments shown below.

[0568] <Example 1>

[0569] Synthesis of PA-1, a polymer with photooriented groups

[0570] The monomer m-1 shown below was synthesized using the method described in Langmuir, 32(36), 9245-9253, (2016) with 2-hydroxyethyl methacrylate (HEMA) (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) and the cinnamoyl chloride derivative described below.

[0571] Cinnamyl chloride derivatives

[0572] [Chemical Formula 1]

[0573]

[0574] Monomer m-1

[0575] [Chemical Formula 2]

[0576]

[0577] Five parts by mass of 2-butanone as a solvent were added to a flask equipped with a cooling tube, thermometer, and stirrer. The mixture was heated to reflux in a water bath while nitrogen was bubbled into the flask at a rate of 5 mL / min. A solution was then prepared by dropwise addition of five parts by mass of monomer m-1, five parts by mass of CYCLOMER M100 (methyl 3,4-epoxycyclohexyl methacrylate, manufactured by Daicel Corporation), one part by mass of 2,2'-azobis(isobutyronitrile) as a polymerization initiator, and five parts by mass of 2-butanone as a solvent over 3 hours. The mixture was then stirred while maintaining reflux for 3 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, and then 30 parts by mass of 2-butanone were added and diluted to obtain a polymer solution of approximately 20% by mass. The obtained polymer solution was added to a large excess of methanol to precipitate the polymer. The recovered precipitate was filtered off and washed with a large amount of methanol. The precipitate was then dried under air at 50°C for 12 hours to obtain polymer PA-1 with photooriented groups (see below). The obtained polymer PA-1 had an epoxy equivalent of 396 g / eq and a weight-average molecular weight of 28,000.

[0578] [Chemical Formula 3]

[0579]

[0580] [Fabrication of photoalignment film P-1]

[0581] Using a #2.4 wire rod, the following photo-aligned film forming composition PC-1 was continuously coated onto a commercially available triacetyl cellulose membrane "Z-TAC" (manufactured by FUJIFILM Corporation). The coated support was dried with warm air at 140°C for 120 seconds, followed by polarized ultraviolet irradiation (10 mJ / cm²). 2 (Using an ultra-high pressure mercury lamp), a photo-alignment film P-1 was formed.

[0582]

[0583] PAG (a heat-generating acid agent)

[0584] [Chemical Formula 4]

[0585]

[0586] [Formation of optical film A]

[0587] The following polymeric liquid crystal composition 1 was coated onto the photoalignment film P-1 using a #13 wire rod. After heating at 110°C for 100 seconds, the composition layer was irradiated with ultraviolet light (500 mJ / cm²) at 55°C under a nitrogen atmosphere using a metal halide lamp (manufactured by EYE GRAPHICS Co., Ltd.). 2 This process fixes the orientation of the liquid crystal compound, thus forming an optically anisotropic film A1.

[0588] Next, the polymeric liquid crystal composition 2 was coated onto the optically anisotropic film A1 using a #16 wire rod. After heating at 110°C for 100 seconds, the composition layer was irradiated with ultraviolet light (irradiation dose: 500 mJ / cm²) at 55°C under nitrogen atmosphere using a metal halide lamp. 2 The process of coating the polymeric liquid crystal composition 2 with ultraviolet light is repeated three times to form an optically anisotropic film A2.

[0589] Furthermore, the following polymeric liquid crystal composition 3 was coated onto the optical anisotropic film A2 using a wire rod of #13. After heating at 110°C for 100 seconds, the composition layer was irradiated with ultraviolet light (irradiation dose: 500 mJ / cm²) at 55°C under a nitrogen atmosphere using a metal halide lamp. 2 This formed an optically anisotropic film A3.

[0590] Based on the above, an optical film A was fabricated by sequentially stacking a support / optical alignment film P-1 / optical anisotropic film A1 / optical anisotropic film A2 / optical anisotropic film A3.

[0591] Furthermore, in the fabricated optical film A, optical anisotropic films A1 and A3 correspond to λ / 4 sheets. And optical anisotropic film A2 corresponds to... Figure 1 The liquid crystal polarizing interference element 216 is illustrated in the figure. Therefore, the optical film A produced corresponds to the aforementioned optical element.

[0592] Furthermore, each layer constituting optical film A is a layer formed by fixing the alignment state of the liquid crystal compound as shown in Table 1 in the following section. The phase difference of each layer constituting optical film A is also shown in Table 1 in the following section.

[0593]

[0594] Liquid crystal compound A-1

[0595] [Chemical Formula 5]

[0596]

[0597] Liquid crystal compound B-1

[0598] [Chemical Formula 6]

[0599]

[0600] Polymerization initiator S-1

[0601] [Chemical Formula 7]

[0602]

[0603] Chiral reagent A

[0604] [Chemical Formula 8]

[0605]

[0606] Chiral reagent B

[0607] [Chemical Formula 9]

[0608]

[0609] Compound L-1

[0610] [Chemical Formula 10]

[0611]

[0612] Compound T-1

[0613] [Chemical Formula 11]

[0614]

[0615] Furthermore, when the polymerizable liquid crystal composition 2 is coated, the liquid crystal compound A-1 (rod-shaped liquid crystal compound) is concentrated on the air interface side, and the liquid crystal compound B-1 (disc-shaped liquid crystal compound) is concentrated on the side opposite to the air interface side. That is, the layers containing the disc-shaped liquid crystal compound and the layers containing the rod-shaped liquid crystal compound are separated from the photoalignment film P-1 side. Chiral reagent A and chiral reagent B are present in each of the separated layers. Chiral reagent A exerts a right-handed helical torsion force on both the disc-shaped and rod-shaped liquid crystal compounds. On the other hand, chiral reagent B exerts a left-handed helical torsion force only on the rod-shaped liquid crystal compound. As a result, the layer containing the disc-shaped liquid crystal compound becomes right-handedly twisted, and the layer containing the rod-shaped liquid crystal compound becomes left-handedly twisted, thereby forming the optically anisotropic layer A2 described in Table 1 below.

[0616]

[0617]

[0618]

[0619] Chiral reagent C

[0620] [Chemical Formula 12]

[0621]

[0622] <Example 2>

[0623] The amounts of chiral reagents A, B, and C in the polymerizable liquid crystal composition and the diameter of the wire rod were changed. Otherwise, optical film B was fabricated using the same steps as in Example 1. Specifically, optical film B was fabricated by sequentially stacking a support / optical alignment film P-1 / optically anisotropic film B1 / optically anisotropic film B2 / optically anisotropic film B3. Optically anisotropic films B1, B2, and B3 correspond to λ / 4 sheets, respectively. Figure 1 The liquid crystal polarizing interference element 216 and λ / 4 sheet shown are optical film B, which corresponds to the aforementioned optical elements.

[0624] When fabricating optical film B, the conditions are adjusted to achieve the phase difference shown in Table 2 below. Furthermore, each layer constituting optical film B is formed by aligning the liquid crystal compound in the manner shown in Table 2 below.

[0625] <Example 3>

[0626] The amounts of chiral reagents A, B, and C in the polymerizable liquid crystal composition and the diameter of the wire rod were changed. Otherwise, the optical film C was fabricated using the same steps as in Example 1. Specifically, an optical film C was fabricated by sequentially stacking a support / optical alignment film P-1 / optically anisotropic film C1 / optically anisotropic film C2 / optically anisotropic film C3. Optically anisotropic film C1, optically anisotropic film C2, and optically anisotropic film C3 correspond to λ / 4 sheets, respectively. Figure 1 The liquid crystal polarizing interference element 216 and λ / 4 sheet shown are optical film C, which corresponds to the aforementioned optical elements.

[0627] When fabricating optical film C, the conditions are adjusted to achieve the phase difference shown in Table 3 below. Furthermore, each layer constituting optical film C is formed by fixing the alignment state of the liquid crystal compound as shown in Table 3 below.

[0628] <Example 4>

[0629] First, a film with a support / photoalignment film P-1 stacked on it was fabricated using the same steps as in Example 1.

[0630] (Formation of optical film D)

[0631] The following polymerizable liquid crystal composition 4 was coated onto the photoalignment film P-1 using a #4 wire rod. After heating at 100°C for 80 seconds, the composition layer was irradiated with ultraviolet light (irradiation dose: 19 mJ / cm²) at 40°C using a 365 nm LED lamp (manufactured by AcroEdge Co., Ltd.) in oxygen-containing air (oxygen concentration: approximately 20 vol%). 2 Next, the obtained composite layer was heated at 90°C for 10 seconds, and then irradiated with ultraviolet light at 55°C under nitrogen atmosphere using a metal halide lamp (irradiation dose: 500 mJ / cm). 2 This fixes the orientation of the liquid crystal compound, forming an optically anisotropic film 4.

[0632] Next, the polymerizable liquid crystal composition 5 was coated onto the optically anisotropic film 4 using a #7 wire rod. After heating at 100°C for 80 seconds, the composition layer was irradiated with ultraviolet light (irradiation dose: 35 mJ / cm²) using a 365 nm LED lamp at 40°C in oxygen-containing air. 2By irradiating with ultraviolet light as described above, polymerization occurs only on the side of the composition layer opposite to the air interface side, and the chiral reagent C contained on the air interface side is deactivated. After heating the obtained composition layer at 90°C for 10 seconds, the composition layer is irradiated with ultraviolet light using a metal halide lamp at 55°C under a nitrogen atmosphere. That is, the twisting direction of the liquid crystal compound on the air interface side of the composition layer is set to be opposite to the direction of the layer on the opposite side of the air interface side, and the entire composition layer is polymerized. The process from coating the polymerizable liquid crystal composition 5 to ultraviolet irradiation based on the metal halide lamp is repeated three times to form an optically anisotropic film 5.

[0633] Furthermore, the polymerizable liquid crystal composition 6 was coated onto the optically anisotropic film 5 using a #4 wire rod. After heating at 100°C for 80 seconds, the composition layer was irradiated with ultraviolet light (irradiation dose: 38 mJ / cm²) using a 365 nm LED lamp at 40°C in oxygen-containing air. 2 Next, the obtained composite layer was heated at 90°C for 10 seconds, and then irradiated with ultraviolet light at 55°C under nitrogen atmosphere using a metal halide lamp (irradiation dose: 500 mJ / cm). 2 This fixes the orientation of the liquid crystal compound, forming an optically anisotropic film 6.

[0634] Based on the above, an optical film D was fabricated, consisting of a support, an optical alignment film P-1, an optically anisotropic film 4, an optically anisotropic film 5, and an optically anisotropic film 6 stacked sequentially. Furthermore, in the fabricated optical film D, optically anisotropic films 4 and 6 correspond to λ / 4 sheets. And optically anisotropic film 5 corresponds to... Figure 1 The liquid crystal polarizing interference element 216 is shown in the figure. Therefore, the optical film D produced corresponds to the aforementioned optical elements.

[0635] Furthermore, each layer constituting the optical film D is a layer formed by fixing the alignment state of the liquid crystal compound as shown in Table 4 in the following section. The phase difference between each layer of the optical film D is also shown in Table 4 in the following section.

[0636]

[0637] Rod-shaped liquid crystal compound A (a mixture of compounds shown below)

[0638] [Chemical Formula 13]

[0639]

[0640] Rod-shaped liquid crystal compound B

[0641] [Chemical Formula 14]

[0642]

[0643] Rod-shaped liquid crystal compound C

[0644] [Chemical Formula 15]

[0645]

[0646]

[0647]

[0648]

[0649] Chiral reagent D

[0650] [Chemical Formula 16]

[0651]

[0652] <Measurement of Optical Properties>

[0653] The optical properties of the optical films A to D fabricated above were determined using Axometrics' Axoscan and its multi-layer analysis software (Multi-Layer Analysis).

[0654] In addition, the orientation axis angle of the liquid crystal compound is 0° with the length direction of the film as the reference. When viewed from the side opposite to the substrate side, the clockwise direction (right turn) is negative and the counterclockwise direction (left turn) is positive.

[0655] Furthermore, regarding the twist angle of the liquid crystal compound, when observing the optical film from the side opposite to the substrate side, with the orientation direction of the liquid crystal compound on the support side (inner side) as a reference, the orientation direction of the liquid crystal compound on the air side (directly in front side) is recorded as negative when it is clockwise (right turn) and positive when it is counterclockwise (left turn).

[0656] [Table 1]

[0657]

[0658] [Table 2]

[0659]

[0660] [Table 3]

[0661]

[0662] [Table 4]

[0663]

[0664] <Fabrication of Circular Polarizers>

[0665] To conduct the "evaluation of the wavelength dependence of transmission" described later, circular polarizers B, G, and R were fabricated as follows. First, circular polarizer G was fabricated. First, a support identical to that in Example 1 was prepared.

[0666] (Formation of alignment film P-10)

[0667] Using a #2.4 wire bar, the coating solution for forming the alignment film P-10 is continuously applied to the support. The support with the coating solution for forming the alignment film P-10 is then dried on a heating plate at 80°C for 5 minutes, thereby forming the alignment film P-10.

[0668]

[0669]

[0670] (Synthesis of polymer A2)

[0671] 100 parts by mass of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 500 parts by mass of methyl isobutyl ketone, and 10 parts by mass of triethylamine were charged into a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, and mixed at room temperature. Then, 100 parts by mass of deionized water were added dropwise over 30 minutes via the dropping funnel, and the mixture was stirred under reflux and reacted at 80°C for 6 hours. After the reaction was complete, the organic phase was removed and washed with a 0.2% ammonium nitrate aqueous solution until the water became neutral. The solvent and water were then removed by distillation under reduced pressure, thereby obtaining an epoxy-containing polyorganosiloxane as a viscous, transparent liquid.

[0672] ¹H-NMR (Nuclear Magnetic Resonance) analysis of the epoxy-containing polyorganosiloxane confirmed the presence of an ethylene oxide-based peak at a theoretical intensity near a chemical shift (δ) of 3.2 ppm, indicating no side reactions involving epoxy groups occurred during the reaction. The epoxy-containing polyorganosiloxane has a weight-average molecular weight (Mw) of 2,200 and an epoxy equivalent of 186 g / mol.

[0673] Next, 10.1 parts by mass of the epoxy-containing polyorganosiloxane obtained above, 0.5 parts by mass of the acryloyl-containing carboxylic acid (TOAGOSEI CO.,LTD., ARONIX M-5300, ω-carboxylated polycaprolactone acrylate (degree of polymerization n≈2)), 20 parts by mass of butyl acetate, 1.5 parts by mass of the cinnamic acid derivative obtained by the method of Synthesis Example 1 of Japanese Patent Application Publication No. 2015-26050, and 0.3 parts by mass of tetrabutylammonium bromide were added to a 100 mL three-necked flask, and the mixture was stirred at 90 °C for 12 hours. After the reaction was completed, the solution was diluted with an equal volume (by mass) of butyl acetate and washed three times with water. The process of concentrating the solution and diluting it with butyl acetate was repeated twice to finally obtain a solution containing a polyorganosiloxane with photooriented groups (polymer A2 below). The weight-average molecular weight Mw of polymer A2 is 9,000. Furthermore, 1H-NMR analysis showed that the content of cinnamic acid groups in polymer A2 was 23.7% by mass.

[0674] Polymer A2

[0675] [Chemical Formula 17]

[0676]

[0677] Low molecular weight compound B2 (Nisshin OilliO Group, Ltd., NOMCORT TAB)

[0678] [Chemical Formula 18]

[0679]

[0680] Crosslinking agent C1 (represented by the following formula, manufactured by Nagase ChemteX Corporation, Denacol EX411))

[0681] [Chemical Formula 19]

[0682]

[0683] Compound D1 (represented by the following formula: Compound D1 (manufactured by Kawaken Fine Chemicals Co., Ltd., aluminum chelate A(W)))

[0684] [Chemical Formula 20]

[0685]

[0686] Compound D2 (represented by the following formula: Compound D2 (manufactured by Toyo Science Corp., Japan, triphenylsilanol))

[0687] [Chemical Formula 21]

[0688]

[0689] (Exposure of alignment film P-10)

[0690] The obtained alignment film P-10 was irradiated with polarized ultraviolet light (20 mJ / cm²). 2 The orientation film P-10 was exposed using an ultra-high pressure mercury lamp.

[0691] <Fabrication of Optical Anisotropic Layer (λ / 4 sheet)>

[0692] Composition C-1 was coated onto alignment film P-10. The coating was heated to 110°C on a hot plate and then cooled to 60°C. After cooling, it was subjected to a high-pressure mercury lamp at 500 mJ / cm² under a nitrogen atmosphere. 2 The coating was irradiated with ultraviolet light at a wavelength of 365 nm, thereby fixing the orientation of the liquid crystal compound and creating an optically anisotropic layer. The resulting optically anisotropic layer has a Δn... 530 ×d(Re(530)) is 132.5nm.

[0693]

[0694]

[0695] Liquid crystal compound L-2

[0696] [Chemical Formula 22]

[0697]

[0698] Liquid crystal compound L-3

[0699] [Chemical Formula 23]

[0700]

[0701] Liquid crystal compound L-4

[0702] [Chemical Formula 24]

[0703]

[0704] Polymerization initiator PI-1

[0705] [Chemical Formula 25]

[0706]

[0707] Leveling agent G-1

[0708] [Chemical Formula 26]

[0709]

[0710] <Fabrication of Circular Polarizer G>

[0711] A linear polarizer was attached to the support side of the aforementioned optical anisotropic layer (λ / 4 layer) using an adhesive to obtain a circular polarizer G.

[0712] <Fabrication of Circular Polarizer B and Circular Polarizer R>

[0713] In the fabrication of the circular polarizer G, the thickness of the optical anisotropy layer is adjusted to achieve the desired Δn of the optical anisotropy layer. 450 ×d(Re(450)) becomes 112.5nm. In addition, circular polarizer B was obtained in the same way as circular polarizer G.

[0714] In the fabrication of the circular polarizer G, the thickness of the optical anisotropy layer is adjusted to achieve the desired Δn of the optical anisotropy layer. 635 ×d(Re(635)) becomes 158.8nm. In addition, the circular polarizer R is obtained in the same way as the circular polarizer G.

[0715] <Wavelength Selectivity Evaluation>

[0716] The polarization conversion efficiency of red, green, and blue light incident on each of the fabricated optical films from the front (0° angle relative to the normal) and from a polar angle of 30° (30° angle relative to the normal) was evaluated.

[0717] Specifically, firstly, two circular polarizers R are arranged facing each other with their optical anisotropy layers facing each other. Furthermore, an optical film is placed between the two circular polarizers R. In this configuration, a laser beam with a center wavelength of red light (635 nm) is incident from the normal direction of the circular polarizer R and converted into circularly polarized light. This circularly polarized light is then incident from the normal direction of the optical film. The circularly polarized light exiting through the optical film is then incident on the circular polarizer R, and the intensity of the red light exiting through the circular polarizer R is measured. That is, the transmittance (T0) of the red laser is measured. R In the incident laser beam described above, the transmission axis of the linear polarizer of the circular polarizer R on the side initially incident on the laser beam is adjusted so that it is parallel to the polarization direction of the laser beam.

[0718] When the above operation is performed, if the optical film produces a phase difference of λ / 2 on the circularly polarized red light (becoming circularly polarized light with opposite rotation direction), the red light is absorbed by the linear polarizer of the circularly polarized plate R on the side opposite to the side of the incident laser beam. On the other hand, if no phase difference is produced on the circularly polarized red light (the rotation direction of the circularly polarized light is not changed), the red light will not be absorbed by the linear polarizer of the circularly polarized plate R on the side opposite to the side of the incident laser beam, and will be emitted as red light.

[0719] Using a circular polarizer G and a laser beam with a center wavelength that outputs green light (530 nm), the transmittance (T) of the green laser beam was measured in the same manner as described above. G ).

[0720] Furthermore, using a circular polarizer B and a laser beam with a center wavelength that outputs green light (450 nm), the transmittance (T) of the blue laser beam was measured in the same manner as described above. B ).

[0721] When in the above T R T G and T B The minimum transmittance value was set as T1, and all other values ​​were set as T2 and T3. The wavelength selectivity of the optical film was evaluated based on the following criteria. The optical film evaluated as A has excellent wavelength selectivity and is therefore preferred.

[0722] A: T1 is below 30%, and T2 and T3 are above 80%.

[0723] B: T1 is below 50%, and T2 and T3 are above 80%.

[0724] Furthermore, T2 and T3 being lower values ​​relative to T1 indicates that the optical film can convert circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction. Also, the measurement wavelength representing T1 indicates that the optical film converts circularly polarized light into circularly polarized light with the opposite rotation direction.

[0725] Furthermore, the same evaluation was conducted by simply changing the orientation of the optical films disposed between each circular polarizer so that the circularly polarized light was incident from a direction tilted 30° relative to the normal direction of the surface of the optical film.

[0726] The evaluation results are shown in Table 5 below.

[0727] [Table 5]

[0728]

[0729] The results shown in Table 5 confirm that the optical films (optical components) of each embodiment can convert only circularly polarized light in a specific wavelength region into circularly polarized light with the opposite rotation direction. Furthermore, in Embodiments 1 and 4, T... G In Example 2, T becomes T1 (minimum transmittance). R In Example 3, T becomes T1. B Become T1.

[0730] Based on a comparison of Example 4 with other examples, it was confirmed that when either a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound is included in the liquid crystal compound in the first liquid crystal layer, and the other is included in the liquid crystal compound in the second liquid crystal layer, the wavelength selectivity is excellent even when circularly polarized light is incident from a direction tilted relative to the normal direction of the surface of the optical film (optical element).

[0731] <Optical Components>

[0732] Following the steps below, a first optical anisotropic component, a second optical anisotropic component, and a third optical anisotropic component were fabricated.

[0733] [Forming of the first optical anisotropic component]

[0734] (Support structure)

[0735] A glass substrate was prepared as a support.

[0736] (Formation of the orientation film)

[0737] The following alignment film forming coating solution is applied to a support by spin coating. The support with the coating solution is then dried on a hot plate at 60°C for 60 seconds to form an alignment film.

[0738] Coating solution for oriented film formation

[0739]

[0740] -Raw material A for photoorientation-

[0741] [Chemical Formula 27]

[0742]

[0743] (Exposure of the alignment film)

[0744] use Figure 18 The exposure apparatus shown exposes the alignment film, thereby forming an alignment film PG-1 with an alignment pattern.

[0745] The exposure apparatus used a laser beam with an emission wavelength of 355 nm as the laser source. The exposure dose based on the interference light was set to 1000 mJ / cm². 2 .

[0746] (Formation of an anisotropic optical layer)

[0747] As a liquid crystal composition for forming the first optical anisotropic layer, the following composition E-1 was prepared.

[0748] Composition E-1

[0749]

[0750] Liquid crystal compound L-5

[0751] [Chemical Formula 28]

[0752]

[0753] Chiral reagent C1

[0754] [Chemical Formula 29]

[0755]

[0756] An optically anisotropic layer is formed by multi-coating composition E-1 onto an alignment film PG-1. Multi-coating refers to the repeated process of applying the following steps: first, a first layer of composition E-1 is coated onto the alignment film; after heating and UV curing, a liquid crystal immobilization layer is formed; then, subsequent layers are overlapped onto this liquid crystal immobilization layer, and the process is repeated with heating and UV curing. Through multi-coating, even as the total thickness of the optically anisotropic layer increases, the alignment direction of the alignment film is reflected from the lower surface to the upper surface of the optically anisotropic layer.

[0757] First, in the first layer, the above composition E-1 is coated onto the alignment film PG-1, and the coating is heated to 80°C on a hot plate. Then, under nitrogen atmosphere, a high-pressure mercury lamp at 300 mJ / cm² is used. 2 The coating is irradiated with ultraviolet light of wavelength 365nm, thereby fixing the orientation of the liquid crystal compound and forming a liquid crystal immobilization layer.

[0758] After the second layer, an additional layer is coated onto the liquid crystal immobilization layer. This layer is then heated under the same conditions as described above and cured with ultraviolet light to create the liquid crystal immobilization layer. This process of overlapping coatings is repeated until the total thickness reaches the desired value, forming an optically anisotropic layer and thus creating a liquid crystal diffraction element.

[0759] Furthermore, the birefringence Δn of the cured layer of liquid crystal composition E-1 was determined by measuring the retardation value and film thickness of the liquid crystal immobilization layer (cured layer). This liquid crystal immobilization layer was obtained by coating the liquid crystal composition E-1 onto a separately prepared support with an alignment film for retardation measurement, aligning the liquid crystal compound horizontally on the substrate, and then immobilizing it by irradiating it with ultraviolet light. Δn can be calculated by dividing the retardation Re value by the film thickness. The retardation value was measured at the target wavelength using an Axoscan (manufactured by Axometrix), and the film thickness was measured using a scanning electron microscope.

[0760] In the optically anisotropic layer, the Δn of the liquid crystal was confirmed using polarizing microscopy. 550 The thickness (Re(550)) ultimately becomes 150 nm, and it becomes a periodically oriented surface. Furthermore, in the liquid crystal alignment pattern of this optically anisotropic layer, one period of 180° rotation of the optical axis of the liquid crystal compound is 0.8 μm. Also, in this optically anisotropic layer, the twist angle in the thickness direction of the liquid crystal compound is 83°. Hereinafter, unless otherwise specified, “Δn” is described in the same manner. 550 Measurements such as ×d”.

[0761] The following composition E-2 was prepared as a liquid crystal composition for forming the second optical anisotropic layer.

[0762] Composition E-2

[0763]

[0764] The thickness of the optical anisotropic layer was adjusted using composition E-2. In addition, a second optical anisotropic layer was formed in the same manner as the first optical anisotropic layer.

[0765] In the optically anisotropic layer, the Δn of the liquid crystal was confirmed using polarizing microscopy. 550 The thickness (Re(550)) ultimately becomes 335 nm, forming a periodically oriented surface. Furthermore, in the liquid crystal alignment pattern of this optically anisotropic layer, one period of 180° rotation of the optical axis of the liquid crystal compound is 0.8 μm. Also, in this optically anisotropic layer, the twist angle in the thickness direction of the liquid crystal compound is 8°.

[0766] The following composition E-3 was prepared as a liquid crystal composition for forming the third optical anisotropy layer.

[0767] Composition E-3

[0768]

[0769] The thickness of the optical anisotropic layer was adjusted using composition E-3. In addition, a third optical anisotropic layer was formed in the same manner as the first optical anisotropic layer.

[0770] In the optically anisotropic layer, the Δn of the liquid crystal was confirmed using polarizing microscopy. 550 The thickness (Re(550)) ultimately becomes 170 nm, forming a periodically oriented surface. Furthermore, in the liquid crystal alignment pattern of this optically anisotropic layer, one period of 180° rotation of the optical axis of the liquid crystal compound is 0.8 μm. Also, in this optically anisotropic layer, the twist angle in the thickness direction of the liquid crystal compound is -78°. Thus, a first optically anisotropic component comprising the first liquid crystal diffraction element A1 was fabricated.

[0771] Chiral reagent C2

[0772] [Chemical Formula 30]

[0773]

[0774] [Fabrication of the second optical anisotropic component]

[0775] (Formation of the orientation film)

[0776] An alignment film was formed in the same manner as described above. Furthermore, the exposure of the alignment film was performed according to the steps shown below.

[0777] (Exposure of the alignment film)

[0778] use Figure 18 The exposure apparatus shown exposes the alignment film, thereby forming an alignment film PG-2 with an alignment pattern.

[0779] The exposure apparatus used a laser beam with an emission wavelength of 355 nm as the laser source. The exposure dose based on the interference light was set to 1000 mJ / cm². 2 .

[0780] Except for using the alignment film PG-2, a second optical anisotropic component including the second liquid crystal diffraction element A2 was fabricated by adjusting the phase difference of each optical anisotropic layer to the same steps as the first liquid crystal diffraction element A1.

[0781] In the fabricated second liquid crystal diffraction element A2, the Δn of the first optical anisotropy layer 550 The thickness (Re(550)) becomes 150 nm, the twist angle in the thickness direction of the liquid crystal compound is 83°, and the Δn of the second optical anisotropy layer... 550 The thickness (Re(550)) becomes 335 nm, the twist angle in the thickness direction of the liquid crystal compound is 8°, and the Δn of the third optical anisotropy layer...550 The thickness (Re(550)) is 170 nm, and the twist angle in the thickness direction of the liquid crystal compound is -78°. In addition, in the liquid crystal alignment pattern of the optical anisotropy layer of this liquid crystal diffraction element, one period of 180° rotation of the optical axis of the liquid crystal compound is 10.0 μm.

[0782] [Fabrication of the Third Optical Anisotropic Component]

[0783] (Formation of the orientation film)

[0784] An alignment film was formed on the support in the same manner as described above. Furthermore, the exposure of the alignment film was performed according to the steps shown below.

[0785] (Exposure of the alignment film)

[0786] use Figure 18 The exposure apparatus shown exposes the alignment film, thereby forming an alignment film PG-3 with an alignment pattern.

[0787] The exposure apparatus used a laser beam with an emission wavelength of 355 nm as the laser source. The exposure dose based on the interference light was set to 1000 mJ / cm². 2 .

[0788] In addition to using the alignment film PG-3, a third optical anisotropic component including the third liquid crystal diffraction element A3 was fabricated by adjusting the phase difference of each optical anisotropic layer to the same steps as the first liquid crystal diffraction element A1.

[0789] In the fabricated third liquid crystal diffraction element A3, the Δn of the first optical anisotropy layer 550 The thickness (Re(550)) becomes 150 nm, the twist angle in the thickness direction of the liquid crystal compound is 83°, and the Δn of the second optical anisotropy layer... 550 The thickness (Re(550)) becomes 335 nm, the twist angle in the thickness direction of the liquid crystal compound is 8°, and the Δn of the third optical anisotropy layer... 550 The thickness (Re(550)) is 170 nm, and the twist angle in the thickness direction of the liquid crystal compound is -78°. In addition, in the liquid crystal alignment pattern of the optical anisotropy layer of this liquid crystal diffraction element, one period of 180° rotation of the optical axis of the liquid crystal compound is 8.9 μm.

[0790] [Fabrication and Evaluation of Optical Components]

[0791] An optical element was fabricated by sequentially stacking the above-mentioned liquid crystal diffraction element A1 (optical anisotropic layer), the optical film (optical element) of Example 2, the above-mentioned liquid crystal diffraction element A2 (optical anisotropic layer), the optical film (optical element) of Example 1, and the above-mentioned liquid crystal diffraction element A3 (optical anisotropic layer).

[0792] Regarding the fabricated optical element, the angles of the transmitted and diffracted light relative to the incident light were measured for red, green, and blue light incident from the front (at an angle of 0° relative to the normal). The angle of the transmitted and diffracted light is the angle of the transmitted and diffracted light relative to the incident light when the incident direction of the incident light is set to 0°.

[0793] Specifically, a laser beam with center wavelengths of output red (635nm), green (532nm), and blue (450nm) light was perpendicularly incident on the fabricated optical element from a position 10cm away from the normal direction. The transmitted and diffracted light was captured by a screen positioned 100cm away, and the transmission angle was calculated. Furthermore, in this example, the design wavelength λa for the longest wavelength was set to 635nm, the design wavelength λb for the middle wavelength was set to 532nm, and the design wavelength λc for the shortest wavelength was set to 450nm.

[0794] In addition, the laser beam was incident perpendicularly onto the aforementioned circular polarizers B, G, and R, which correspond to each wavelength, to generate circularly polarized light. This light was then incident onto the fabricated optical element and evaluated.

[0795] Based on the average transmission angle θ of red, green, and blue light ave The maximum transmission angle θ among red, green, and blue light. max and minimum transmission angle θ min The wavelength dependence PE of the diffraction angle of the transmitted diffracted light is calculated using the following formula. The smaller the PE, the lower the wavelength dependence of the diffraction angle of the transmitted diffracted light.

[0796] PE[%]=[(θ max -θ min ) / θ ave ]×100

[0797] In the optical components fabricated, the calculated PE was confirmed to be below 5%, and the wavelength dependence of the diffraction angle of the transmitted diffracted light was low.

[0798] Symbol Explanation

[0799] 10 - Optical element; 12 - First optical anisotropic component; 14 - Second optical anisotropic component; 16 - Third optical anisotropic component; 18G, 18R, 100 - Wavelength selective retardation plate; 20 - Support; 24A, 24B, 24C - Alignment film; 26A - First optical anisotropic layer; 26B - Second optical anisotropic layer; 26C - Third optical anisotropic layer; 30 - Liquid crystal compound; 30A - Optical axis; 34 - Optical anisotropic layer; 40 - Display; 42 - Light guide plate; 60, 80 - Exposure device; 62, 82 - Laser; 64, 84 - Light source; 68 - Beam splitter; 70A, 70B 90A, 90B - Reflectors; 72A, 72B, 96 - λ / 4 plates; 86, 94 - Polarizing beam splitters; 92 - Lens; 112 - First waveplate; 114 - Second waveplate; 116 - Third waveplate; 210, 230 - Filters; 212 - First λ / 4 plate; 214 - Second λ / 4 plate; 216, 246 - Liquid crystal polarizing interference elements; 218 - Liquid crystal compound (rod-shaped liquid crystal compound); 220, 232 - First liquid crystal layer; 224, 234 - Second liquid crystal layer; 226, 236 - Liquid crystal layer group; D1 - Slow axis direction in the first plane; D2 - Slow axis direction in the second plane; D3 - Slow axis direction in the third plane; B R B 2R - Blue light, right-handed circularly polarized light, G R G 1R G 2R G 3R - Green light is right-handed circularly polarized light, R R R 1R R 3R -Right-handed circularly polarized light, B 1L B 3L - Blue light, left-handed circularly polarized light, G 1L G 2L -Left-handed circularly polarized green light, R 1L R 2L - Left-handed circularly polarized red light, M-laser beam, MA, MB-ray, MP-P-polarized light, MS-S-polarized light, P O - Linearly polarized light, P R - Right-handed circularly polarized light, P L - Left-handed circularly polarized light, Q1, Q2 - absolute phase, E1, E2 - equiphase surfaces, U - user.

Claims

1. An optical element comprising, sequentially, a first λ / 4 sheet, an optical laminate, and a second λ / 4 sheet, wherein, The optical laminate has two or more liquid crystal layer groups in the thickness direction. Each liquid crystal layer group consists of a first liquid crystal layer formed by fixing a liquid crystal compound that is twisted and oriented in the thickness direction, and a second liquid crystal layer formed by fixing a liquid crystal compound that is twisted and oriented in the thickness direction, wherein the twisting direction of the liquid crystal compound is opposite to the twisting direction of the liquid crystal compound in the first liquid crystal layer. In the liquid crystal layer group, the orientation direction of the liquid crystal compound on the surface of the first liquid crystal layer on the side of the second liquid crystal layer is parallel to the orientation direction of the liquid crystal compound on the surface of the second liquid crystal layer on the side of the first liquid crystal layer. The twist angle of the liquid crystal compound in the first liquid crystal layer is equal to the twist angle of the liquid crystal compound in the second liquid crystal layer.

2. The optical element according to claim 1, wherein, Either a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound is included in the liquid crystal compound in the first liquid crystal layer, and the other is included in the liquid crystal compound in the second liquid crystal layer.

3. The optical element according to claim 1, wherein, At least one of the first λ / 4 sheet and the second λ / 4 sheet is a laminate consisting of a liquid crystal layer A formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction and a liquid crystal layer B formed by fixing a liquid crystal compound oriented in a twisted manner along the thickness direction.

4. The optical element according to claim 3, wherein, The twist angle of the liquid crystal compound in liquid crystal layer A is 16.5–36.5°, and the refractive index difference Δn of liquid crystal layer A is... A With respect to the thickness d of the liquid crystal layer A A The product Δn A d A The wavelength range is 252–312 nm. The twist angle of the liquid crystal compound in liquid crystal layer B is 68.6–88.6°, and the refractive index difference Δn of liquid crystal layer B is... B With respect to the thickness d of the liquid crystal layer B B The product Δn B d B The wavelength range is 110–170 nm.

5. The optical element according to claim 3, wherein, The liquid crystal layer A is disposed on the optical laminate side. The orientation direction of the liquid crystal compound on the side surface of the liquid crystal layer A of the optical laminate is parallel to the orientation direction of the liquid crystal compound on the side surface of the optical laminate of the liquid crystal layer A.

6. The optical element according to claim 3, wherein, The orientation direction of the liquid crystal compound on the side surface of liquid crystal layer B of liquid crystal layer A is parallel to the orientation direction of the liquid crystal compound on the side surface of liquid crystal layer A of liquid crystal layer B.

7. An optical element having: Multiple optically anisotropic layers, formed using a composition comprising a liquid crystal compound, and having a liquid crystal alignment pattern that changes while continuously rotating in at least one in-plane direction originating from the optical axis of the liquid crystal compound; and The optical element according to any one of claims 1 to 6 is disposed between at least one pair of two adjacent optical anisotropic layers in the plurality of optical anisotropic layers, and, In the liquid crystal alignment pattern of the optical anisotropy layer, when the length of the 180° rotation of the orientation of the optical axis originating from the liquid crystal compound in one direction, where the orientation changes while rotating continuously, is defined as one cycle, the length of one cycle of at least one optical anisotropy layer is different from that of the other optical anisotropy layers.

Images