Optical film

Abstract

The present specification discloses geometric phase optical elements, methods of manufacture thereof, and uses thereof. The present specification discloses geometric phase optical elements suppressed to have no or very small wavelength dependencies, methods of making the same, and uses thereof. In the present specification, disclosed are a geometric phase optical element having no or small wavelength dependence by using a liquid crystal compound having a specific structure, controlling the thickness of a liquid crystal layer, and adjusting a manufacturing method thereof, a manufacturing method thereof, and a use thereof.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0120854, dated September 23, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to optical films and their uses. Background Art

[0003] A geometric phase optical element is an element that records the wavefront of light on a recording medium using a holographic polarization interference pattern, and is a flat optical element that can be manufactured in a thinner form than existing elements using dynamic phase difference. Such a geometric phase optical element is also called a so-called PBP (Pancharatnam Berry Phase) optical element.

[0004] Such a geometric phase optical element can be applied to various purposes, and its representative use is application to VR (Virtual Reality), AR (Augmented Reality) or MR (Mixed Reality) systems.

[0005] For example, the geometric phase optical element may be applied as part of an optical assembly in a HMD (head-mounted display), which may be part of a VR, AR and / or MR system.

[0006] The geometric phase optical element can act as a geometric phase grating and / or a geometric phase lens in the system.

[0007] When a geometric phase optical element is realized using a liquid crystal compound (e.g., a so-called reactive liquid crystal compound (reactive mesogen)), a problem known so far is that it is very difficult to ensure the orientation of the liquid crystal compound. In order to form a geometric phase optical element, an orientation in which the slow axis of the liquid crystal compound rotates along any one or more directions in a plane is required, and it is very difficult to achieve such an orientation.

[0008] Another problem with geometric phase optics is that the performance of the optics is highly wavelength dependent. When a geometric phase optic is wavelength dependent, the diffraction angle, refraction angle, or focal length varies depending on the wavelength of light, which leads to various problems including an optical defect known as CA (chromatic aberration).

[0009] A conventional technique for solving such a problem is a multilayer optical element constructed by laminating at least three geometric phase lenses corresponding to the respective wavelengths of RGB (eg, Non-Patent Document 1). In Non-Patent Document 1, the geometric phase lens is implemented using a so-called normal dispersion liquid crystal compound.

[0010] If a geometric phase lens can be implemented using a reverse dispersion liquid crystal compound, a geometric phase optical element can be provided that solves the problem of wavelength dependence while having a small number of layers (which are optionally single layers).

[0011] However, most of the known reverse dispersion liquid crystal compounds have poor orientation, so that they cannot stably achieve complex orientation such as geometric phase orientation.

[0012] [Prior art literature]

[0013] [Non-patent literature]

[0014] (Non-patent document 1) Tao Zhan et al., Adv. Optical Mater. 2019, 1901360 Summary of the invention

[0015] Technical issues

[0016] The present specification discloses a geometric phase optical element, a method for manufacturing the same, and uses thereof. The present specification discloses a geometric phase optical element suppressed to have no or very little wavelength dependence, a method for manufacturing the same, and uses thereof. In the present specification, a geometric phase optical element having no or little wavelength dependence by controlling the thickness of the liquid crystal layer and adjusting the manufacturing method by using a liquid crystal compound having a specific structure, a method for manufacturing the same, and uses thereof are disclosed.

[0017] Technical Solution

[0018] This specification discloses an optical film.

[0019] The optical film includes a liquid crystal layer. In the present specification, the liquid crystal layer means a layer containing an oriented liquid crystal compound. For example, based on the total weight of the liquid crystal layer, the lower limit of the content of the oriented liquid crystal compound in the liquid crystal layer can be about 50 weight%, 55 weight%, 60 weight%, 65 weight%, 70 weight%, 75 weight%, 80 weight%, 85 weight%, 90 weight%, or 95 weight%, and based on the total weight of the liquid crystal layer, the upper limit can be about 100 weight%, 98 weight%, 96 weight%, 94 weight%, 92 weight%, or 90 weight%. The content can be in a range greater than or equal to or greater than any one of the above lower limits; or in a range less than or equal to or less than any one of the above upper limits, and greater than or equal to or greater than any one of the above lower limits.

[0020] The liquid crystal layer may be a so-called active liquid crystal layer or a passive liquid crystal layer. In this specification, the term active liquid crystal layer means a liquid crystal layer in which the orientation of the liquid crystal compound in the liquid crystal layer can be changed by an external action (e.g., application of an external electric field) without being fixed, and the term passive liquid crystal layer means a liquid crystal layer in which the orientation of the liquid crystal compound is fixed and not changed by an external action. For example, a passive liquid crystal layer may be formed when a so-called RM (reactive mesogen) is oriented and then the orientation is fixed by polymerization or the like.

[0021] The liquid crystal layer may contain a so-called T-type liquid crystal compound as the liquid crystal compound. As is well known, the term T-type liquid crystal compound is a liquid crystal compound in which the liquid crystal element skeleton of the liquid crystal compound is formed in a T-type. The T-type liquid crystal compound may have excellent orientation, and in particular, may effectively achieve geometric phase orientation.

[0022] Based on the weight of the total liquid crystal compound contained in the liquid crystal layer, the lower limit of the content of the T-type liquid crystal compound can be about 50 weight%, 55 weight%, 60 weight%, 65 weight%, 70 weight%, 75 weight%, 80 weight%, 85 weight%, 90 weight%, or 95 weight%, and the upper limit thereof can be about 100 weight%, 98 weight%, 96 weight%, 94 weight%, 92 weight%, or 90 weight%. The content can be in a range greater than or equal to or greater than any one of the above lower limits; or in a range less than or equal to or less than any one of the above upper limits, and greater than or equal to or greater than any one of the above lower limits.

[0023] As the T-type liquid crystal compound, a liquid crystal compound having so-called reverse wavelength dispersion can be used.

[0024] In this specification, reverse wavelength dispersion means a property in which R(450) / R(550) of the liquid crystal compound in the following formula A is within a predetermined range. R(450) / R(550) within the predetermined range is R(450) / R(550) determined in a state where the liquid crystal compound is uniaxially aligned, which is evaluated in the manner described in "Test Example 1. Evaluation of R(450) / R(550)" of the Example section in this specification.

[0025] [Formula A]

[0026] R(450) / R(550)

[0027] In Formula A, R(450) is the in-plane phase difference of the liquid crystal compound for a wavelength of 450 nm, and R(550) is the in-plane phase difference of the liquid crystal compound for a wavelength of 550 nm.

[0028] In this specification, the term in-plane phase difference is a value determined according to the following Formula B.

[0029] [Formula B]

[0030] Rin=d×(nx-ny)

[0031] In formula B, Rin is the plane phase difference, nx and ny are the refractive indices of the layer formed by the liquid crystal compound in the x-axis direction (slow axis direction) and the y-axis direction (fast axis direction), respectively, and d is the thickness of the liquid crystal layer (unit: nm).

[0032] By substituting nx and ny according to the wavelength into the above formula B, the in-plane phase difference for a desired wavelength can be obtained.

[0033] The lower limit of R(450) / R(550) of the liquid crystal compound in the above formula A can be about 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, or 0.79, and the upper limit thereof can be about 1, 0.99, 0.98, 0.97, 0.96, 0.95, 0.94, 0.93, 0.92, 0.91, 0.90, 0.89, 0.88, 0.87, 0.86, 0.85, 0.84, 0.83, 0.82, 0.81, 0.80, or 0.79. R(450) / R(550) may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0034] The R(650) / R(550) of the liquid crystal compound can also be adjusted. R(650) is the in-plane phase difference of the liquid crystal compound for light with a wavelength of 650 nm, and R(550) is the in-plane phase difference of the liquid crystal compound for light with a wavelength of 550 nm. The method for measuring R(650) / R(550) is basically the same as the method for measuring R(450) / R(550), and only the measuring wavelength needs to be changed. The upper limit of R(650) / R(550) can be about 1.19, 1.18, 1.17, 1.16, 1.15, 1.14, 1.13, 1.12, 1.11, 1.1, or 1.08, and the lower limit can be about 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, or 1.09. R(650) / R(550) may be within a range greater than or equal to or greater than any of the above lower limits; within a range less than or equal to or less than any of the above upper limits; or within a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0035] The liquid crystal compound in the liquid crystal layer may be in an aligned state, and such an alignment may be a so-called geometric phase alignment.

[0036] In this specification, the term geometric phase orientation means an orientation in which a liquid crystal layer functions as a so-called geometric phase lens or a geometric phase grating by the orientation of liquid crystal compounds.

[0037] Orientation patterns are known which allow liquid crystal compounds to function as geometric phase lenses or geometric phase gratings.

[0038] When the liquid crystal compound is oriented in a way that it can function as a geometric phase lens, the relevant orientation can be referred to as a geometric phase lens orientation. In addition, when the liquid crystal compound is oriented in a way that it can function as a geometric phase grating, the relevant orientation can be referred to as a geometric phase grating orientation.

[0039] A geometric phase lens orientation can generally be defined as an orientation with an azimuth that varies spatially.

[0040] Figure 1 Schematic diagram of a liquid crystal layer 200 having a geometric phase lens orientation according to an example. The liquid crystal layer 200 generates a corresponding lens profile by the in-plane orientation of the liquid crystal compound. The in-plane orientation of the liquid crystal compound can be defined by an azimuth angle (θ), which generates an optical phase difference T, and the optical phase difference T can be defined by the azimuth angle as 2θ.

[0041] Figure 2is an example of a geometric phase lens orientation 210. In the geometric phase lens orientation, the azimuth angle (θ) of the liquid crystal compound continuously changes along the direction from the center 220 toward the edge 230 of the liquid crystal layer 200, thereby generating a changing pitch (Λ). Here, the pitch (Λ) means a distance required for the azimuth angle of the liquid crystal compound to rotate 180 degrees in the initial state, which may appear as a function of the distance (r) from the center 220 in the orientation of the geometric phase lens.

[0042] In one example, the azimuth angle may satisfy the relationship of the following Equation 9 according to the distance.

[0043] [Formula 9]

[0044] θ(r)={π×r 2} / {2×f×λ}

[0045] In Formula 9, θ(r) is the azimuth angle of the liquid crystal compound in the region of the liquid crystal layer spaced a distance r (unit: mm) from the center of the geometric phase lens orientation, r is the distance, f is the focal length of the geometric phase lens orientation, and λ is the wavelength of the incident light.

[0046] Figure 3 To illustrate the liquid crystal compound along Figure 1 FIG. 240 is a diagram showing the orientation of the y-axis of the liquid crystal layer 200. Figure 3 The spacing change rate can be determined as a function of the distance (r) from the center 220 of the liquid crystal layer. The spacing change rate becomes faster as the distance increases. For example, Figure 3 The spacings Λ0, Λ1 and Λ r With the relationship Λ0>Λ1>Λ r .

[0047] As described above, in the geometric phase lens alignment, the liquid crystal compound may be aligned to have a phase according to at least one direction along the plane of the liquid crystal layer (for example, perpendicular to Figure 1 The azimuth orientation that changes with the distance in the x-axis direction, y-axis direction or z-axis direction.

[0048] At this time, the change in azimuth angle can satisfy the above formula C.

[0049] In the above formula C, f can be appropriately adjusted according to the purpose of the optical film, and for example, its lower limit can be about 1mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, or 95mm, and its upper limit can be about 300mm, 250mm, 200mm, 150mm, 100mm, 95mm, 90mm, 85mm, 80mm, 75mm, 70mm, or 65mm. The focal length f can be in a range greater than or equal to or greater than any of the above lower limits; in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits. In a geometric phase lens, the focal length f can be adjusted by adjusting the change in spacing, and such an adjustment method is known.

[0050] In the above formula C, λ may be any wavelength within the range of 400 nm to 700 nm, or any wavelength within the range of 450 nm to 650 nm, or approximately 550 nm.

[0051] As reference Figure 2 As can be seen, azimuthal variations in the orientation of the geometric phase lens can occur radially in the plane of the liquid crystal layer.

[0052] Figure 4 Schematic diagram of a liquid crystal layer 300 with a geometric phase grating orientation according to an example of the present application is shown. The liquid crystal layer 300 generates a corresponding grating profile by the in-plane orientation of the liquid crystal compound. The in-plane orientation of the liquid crystal compound can be defined by an azimuth angle (θ), which generates an optical phase difference T, and the optical phase difference T can be defined by the azimuth angle as 2θ.

[0053] Figure 5 3 is a diagram showing an example of the orientation 310 of the liquid crystal compound in the geometric phase grating orientation. In the above orientation, the orientation of the liquid crystal compound can be defined as along any specific direction (in Figure 5 In the case of the y-axis direction, the azimuth angle (θ) is continuously changed, wherein the spacing (Λ) is substantially fixed. Here, the spacing has the same meaning as in the case of the geometric phase lens. In one example, Figure 5 As shown in FIG. 1 , the azimuth angle θ of the liquid crystal compound is along one direction (in Figure 5 In the case of y-axis direction), and changes along a direction perpendicular to the one direction (in Figure 5 in the x-axis direction in the case of the above) remains basically constant.

[0054] Figure 6 To illustrate the liquid crystal compound along Figure 4 FIG. 340 is a diagram showing the orientation of the y-axis of the liquid crystal layer 300. Figure 6 It can be seen from FIG. 3 that in the liquid crystal orientation of the geometric phase grating, the rate of change of the pitch is substantially fixed and is not a function of the distance from the center 320 of the grating orientation. For example, in Figure 6 In the figure, the spacings Λ0, Λ1 and Λ r Basically, the relationship Λ0=Λ1=Λ r .

[0055] In the geometric phase grating alignment, the liquid crystal compound may be aligned with an azimuth angle that changes along at least one direction in the plane direction of the liquid crystal layer. As described above, the pitch of the azimuth angle change along one direction of the azimuth angle change may be fixed.

[0056] In the geometric phase grating alignment, regarding the alignment of the liquid crystal compound, the azimuth angle of the liquid crystal compound can be kept constant along a plane direction perpendicular to one direction in which the azimuth angle changes.

[0057] Here, the situation where the pitch of the azimuth angle change is fixed and the azimuth angle is kept constant means that there is basically no change in the pitch and the azimuth angle, wherein the situation where there is basically no change can mean that even if some parts of the pitch and the azimuth angle change slightly, the liquid crystal layer or the optical film as a whole is effectively able to perform the function of a geometric phase grating.

[0058] In the geometric phase grating orientation, the pitch in one direction of the azimuth angle change can be adjusted according to the purpose of the geometric phase grating. That is, the refraction angle of the grating satisfies the following formula D according to the pitch and the reference wavelength, so that the appropriate pitch can be set in consideration of the desired refraction angle.

[0059] [Formula D]

[0060] sinθ=λ / Λ

[0061] In Formula D, θ is the refraction angle, λ is a reference wavelength which is any wavelength in the range of 400 nm to 700 nm, or any wavelength in the range of 450 nm to 650 nm, or about 550 nm, and Λ is the pitch (unit: nm).

[0062] In one example, the lower limit of the pitch of the orientation of the liquid crystal compound may be about 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, or 15 μm, and the upper limit thereof may be about 30 μm, 28 μm, 26 μm, 24 μm, 22 μm, 20 μm, 18 μm, 16 μm, 14 μm, 12 μm, 10 μm, 8 μm, 6 μm, 4 μm, or 2 μm. The pitch in the geometric phase grating orientation may be in a range greater than or equal to or greater than any of the above lower limits; in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0063] Whether the liquid crystal layer has a geometric phase orientation can be determined by a polarizing microscope. That is, as described above, in the geometric phase orientation, the liquid crystal compound rotates to have a varying azimuth angle, so that when observed by a polarizing microscope, it exhibits a pattern of relatively deep shadow lines and relatively shallow shadow lines repeating along the azimuth angle. Therefore, if the repetition of the line pattern is determined by a polarizing microscope, it can be considered that the liquid crystal layer has a geometric phase orientation. In addition, as described above, the spacing (Λ) of the geometric phase orientation is the distance required for the azimuth angle of the liquid crystal compound to rotate 180 degrees in the initial state, and when the azimuth angle of 90 degrees is completed, a deep line or a shallow line appears, so that in the pattern observed by a polarizing microscope, the distance between the two outermost deep shadow lines (or shallow shadow lines) of three adjacent deep shadow lines (or shallow shadow lines) can be approximately specified as the spacing.

[0064] Since the liquid crystal layer contains such a liquid crystal compound with a geometric phase orientation, and the liquid crystal compound has reverse wavelength dispersion while being the above-mentioned T-type liquid crystal compound, the liquid crystal layer or the optical film including it can play the role of a geometric phase lens or a geometric phase grating with little or no wavelength dependence.

[0065] For example, the liquid crystal layer may satisfy at least one of the conditions of the following formula 1 and the conditions of the following formula 2, or may satisfy both the conditions of the following formula 1 and the conditions of the following formula 2. In this case, the case where the liquid crystal layer satisfies the conditions of formula 1 and / or formula 2 means that the conditions of formula 1 and / or formula 2 are satisfied in the entire region of the liquid crystal layer, or the conditions of formula 1 and / or formula 2 are satisfied in at least a partial region of the liquid crystal layer (for example, at least a boundary of the liquid crystal layer).

[0066] For example, in a state where the liquid crystal layer is a single layer, the liquid crystal layer may satisfy the conditions of the following formula 1 and / or formula 2. At this time, in the case where the liquid crystal layer is substantially a single layer, and in the case where the liquid crystal layer includes a plurality of layers, if the type and composition of the liquid crystal compound contained in each liquid crystal layer are the same, the plurality of layers are considered to be a single layer as a whole. That is, as described below, there may be a case where a plurality of sub-liquid crystal layers are formed to form the liquid crystal layer, and even in this case, if the plurality of sub-liquid crystal layers are formed using liquid crystal compounds having the same type and composition, the plurality of sub-liquid crystal layers may be considered to be a single layer as a whole.

[0067] The conditions of Formula 1 are as follows.

[0068] [Formula 1]

[0069] T 平均 ≤5% and SD T ≤1.5

[0070] Formula 1 means that for the liquid crystal layer, SD T is 1.5 or less, and T 平均 Condition of 5% or less.

[0071] At the same time, in Formula 1, T 平均 T B , T G and T R The mean and SD T For the above T B , T G and T R The standard deviation of .

[0072] Here, T B is the linear light transmittance of the liquid crystal layer for light with a wavelength of 450nm, T G is the linear light transmittance of the liquid crystal layer for light with a wavelength of 550nm, and T R It is the linear light transmittance of the liquid crystal layer for light with a wavelength of 610nm.

[0073] Here, the light having wavelengths of 450 nm, 550 nm, and 610 nm may be unpolarized light or circularly polarized light (left-handed or right-handed circularly polarized light), and for example, in the case of Formula 1, it may be unpolarized light.

[0074] With respect to Formula 1, the term linear light transmittance is the transmittance of any region of the liquid crystal layer. Figure 7 The linear light transmittance is the light L incident on any region 1001 of the liquid crystal layer in a direction parallel to the normal line of the liquid crystal layer 100. I The ratio of the direction parallel to the normal through the region 1001 (i.e., given by Figure 7 Arrow L inE1 The light indicated is relative to the Figure 7 Arrow L in I Indicates the transmittance of light).

[0075] The geometric phase optical element plays a role in converging, dispersing or turning incident light by diffracting or refracting the incident light in a predetermined direction according to the state of the incident light. Figure 7 As shown in the example, the geometric phase optical element includes a light incident along the normal direction of the optical element (given by Figure 7 The light indicated by the arrow L1 in FIG. 1 is converted into light emitted in a direction different from the normal direction (indicated by the arrow L1 in FIG. 1 ). Figure 7 Arrow L in E2 Therefore, in theory, in the above region, the straight light transmittance needs to be low, where such a characteristic is also called so-called 0th order leakage. However, when the geometric phase optical element exhibits wavelength dependence, the straight light transmittance does not appear constant for each wavelength, and depending on the wavelength, the straight light transmittance may optionally appear very high.

[0076] However, the liquid crystal layer has little wavelength dependence, so T B 、T G and T R The mean and standard deviation are controlled to be low.

[0077] T in the above formula 1 B 、T G and T R The average value T 平均 is the arithmetic mean, which is therefore calculated as (T B +T G +T R ) / 3. As described in Formula 1, the average value T 平均 The upper limit of can be about 5%, or in another example, it can be about 4.5%, 4%, 3.5%, 3%, 2.5%, or 2%, and the lower limit can be about 0%, 0.5%, 1%, 1.5%, or 2%. The average value can be in the range of less than or equal to or less than any of the above upper limits; or in the range of less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0078] The standard deviation SD in formula 1 T is calculated as (((T 平均 -T B ) 2 +(T 平均 -T G ) 2 +(T平均 -T R ) 2 ) / 3) 0.5 As described in Equation 1, SD T The upper limit of can be about 1.5, and in another example, it can be about 1.4, 1.3, 1.2, 1.1, 1, 0.9, 0.8, or 0.65, and its lower limit can be about 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7. The standard deviation can be in the range of less than or equal to or less than any of the above upper limits; or in the range of less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0079] The T in formula 1 can be B , T G and T R Each of is adjusted so as to satisfy the mean value and standard deviation as described above. R The upper limit of T may be about 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, or 1.5%, and the lower limit thereof may be about 0%, 0.5%, 1%, 1.5%, 2%, or 2.5%. R It may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0080] T in Formula 1 G The upper limit of T may be about 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, or 1.5%, and the lower limit thereof may be about 0%, 0.5%, 1%, or 1.5%. G It may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0081] T in Formula 1 B The upper limit of T may be about 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, or 1.5%, and the lower limit thereof may be about 0%, 0.5%, 1%, 1.5%, 2%, or 2.5%. B It may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0082] The conditions of Formula 2 are as follows.

[0083] [Formula 2]

[0084] I 平均 ≤100×10 -3 cd and sd I ≤25×10 -3

[0085] Formula 2 means that for the liquid crystal layer, SD I is 0.025 or less, and I 平均 The condition is 0.1cd or less.

[0086] In formula 2, I 平均 For I B ,I G and I R The mean and SD I For I B ,I G and I R The standard deviation of .

[0087] I B is the linear light intensity of light with a wavelength of 450nm directed to the liquid crystal layer, I G is the linear light intensity of light with a wavelength of 550nm directed to the liquid crystal layer, and I R It is the linear light intensity of light with a wavelength of 610nm directed to the liquid crystal layer.

[0088] Light with wavelengths of 450 nm, 550 nm and 610 nm may be unpolarized light or circularly polarized light (left-handed or right-handed circularly polarized light), and in the case of Formula 2, for example, it may be circularly polarized light, ie, left-handed circularly polarized light or right-handed circularly polarized light.

[0089] With respect to Formula 2, the term linear light intensity is the intensity of any region of the liquid crystal layer. Figure 7 , the linear light intensity is the light L incident on any area 1001 in a direction parallel to the normal of the liquid crystal layer 100 I The intensity of light passing through the region 1001 of the liquid crystal layer parallel to the normal direction.

[0090] For the reasons described above, in the geometric phase optical element, theoretically, the linear light intensity needs to be low. When the geometric phase optical element exhibits wavelength dependence, the linear light intensity does not appear constant for each wavelength, and may optionally appear very high depending on the wavelength.

[0091] However, the liquid crystal layer has a small wavelength dependence, so I B ,I G and I R The mean and standard deviation are controlled to be low.

[0092] I in the above formula 2 B ,I G and I R The average value I 平均 is the arithmetic mean, so it is calculated as (I B +I G +I R ) / 3. As described in Formula 2, the average value I 平均 The upper limit of may be around 100, and in another example, it may be 95×10 -3 cd, 90×10 -3 cd, 85×10 -3 cd, 80×10 -3 cd, 75×10 -3 cd, 70×10 -3 cd, 65×10 -3 cd, 60×10 -3 cd, 55×10 -3 cd, 50×10 -3 cd, 45×10 -3 cd, 40×10 -3 cd, 35×10 -3 cd, 30×10 -3 cd, 25×10 -3 cd, 20×10 -3 cd, 15×10 -3 cd, or 10×10 -3 cd, and its lower limit can be 0×10 -3 cd, 2×10 -3 cd, 4×10 -3 cd, 6×10 - 3 cd、8×10 -3 cd, 10×10 -3 cd, 12×10 -3 cd, or 14×10 -3 The average value may be within a range of less than, equal to, or less than any of the above upper limits; or within a range of less than, equal to, or less than any of the above upper limits and greater than, equal to, or greater than any of the above lower limits.

[0093] The standard deviation SD in formula 2 I Calculated as (((I 平均 -I B ) 2 +(I 平均 -I G ) 2 +(I平均 -I R ) 2 ) / 3) 0.5 As described in Equation 2, SD I The upper limit can be 25×10 -3 In another example, it may be 20×10 -3 , 15×10 -3 , 10×10 -3 ,9×10 -3 , 8×10 -3 ,7×10 -3 , 6×10 -3 , 5×10 -3 , 4×10 -3 , 3×10 -3 , or 2.5×10 -3 Around, and its lower limit can be 0×10 -3 , 0.1×10 -3 , 0.5×10 -3 , 1×10 -3 , 1.5×10 -3 , 2×10 -3 , 2.5×10 -3 , 3×10 -3 , 3.5×10 -3 , 4×10 -3 , 4.5×10 -3 , 5×10 -3 , 5.5×10 -3 , 6×10 -3 , or 6.5×10 -3 The standard deviation may be within a range of less than, equal to, or less than any of the above upper limits; or within a range of less than, equal to, or less than any of the above upper limits and greater than, equal to, or greater than any of the above lower limits.

[0094] I in Formula 2 can be B ,I G and I R Each of is adjusted so that the mean and standard deviation as described above are satisfied.

[0095] For example, I in Formula 2 RThe upper limit may be about 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.009, 0.008, 0.007, or 0.006, and the lower limit may be about 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, or 0.02. R It may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0096] In formula 2, I G The upper limit may be about 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.009, 0.008, 0.007, or 0.006, and the lower limit may be about 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, or 0.02. G It may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0097] In formula 2, I B The upper limit may be about 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.009, 0.008, 0.007, or 0.006, and the lower limit may be about 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, or 0.02. B It may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0098] In this way, the liquid crystal layer can also exhibit a diffraction efficiency that has no wavelength dependence, or a diffraction efficiency that has low wavelength dependence.

[0099] For example, the liquid crystal layer may satisfy the following formula 3, or may include a region satisfying the following formula 3. Such a region of the liquid crystal layer may be a region satisfying the conditions of the above formula 1 and / or formula 2. In the state of being a single layer as described above, the liquid crystal layer may satisfy the following formula 3, or may include a region satisfying the following formula 3.

[0100] [Formula 3]

[0101] ΔF1 and ΔF2 ≤ 30%

[0102] In Equation 3, ΔF1 is the absolute value of F1 according to the following Equation 4, and ΔF2 is the absolute value of F2 according to the following Equation 5:

[0103] [Formula 4]

[0104] F1=100×(θ R -θ G ) / θ G

[0105] [Formula 5]

[0106] F2=100×(θ B -θ G ) / θ G

[0107] In equations 4 and 5, θ R To satisfy the refraction angle of the following formula 6, θ G The refraction angle satisfies the following equation 7, and θ B is a refraction angle satisfying the following formula 8. The refraction angle may be a refraction angle in the liquid crystal layer or in any region of the liquid crystal layer.

[0108] [Formula 6]

[0109] sinθ R =610 / Λ

[0110] [Formula 7]

[0111] sinθ G =550 / Λ

[0112] [Formula 8]

[0113] sinθ B =450 / ΛIn equations 6 to 8, Λ is the pitch of the geometric phase orientation in the liquid crystal layer or in any region of the liquid crystal layer (unit: nm). The meaning of the pitch of the geometric phase orientation is the same as that described in the geometric phase orientation.

[0114] The geometric phase optical element must play the role of diffracting or refracting the incident light at a predetermined refraction angle according to the state of the incident light. At this time, the refraction angle is the angle formed by the emission direction of the refracted light relative to the normal direction of the optical element. For example, referring to Figure 7 , the normal direction of the liquid crystal layer 100 is in the same direction as the light refracted and emitted by the liquid crystal layer 100 (indicated by arrow L E2 The angle formed between the emission directions of the indicated light) is called the refraction angle.

[0115] When the geometric phase optical element has strong wavelength dependence, the refraction angle varies according to the wavelength in the same region, and such a difference in the refraction angle for each wavelength causes an optical defect.

[0116] Since the liquid crystal layer includes a liquid crystal compound in a geometric phase orientation and has the above-mentioned reverse wavelength dispersion at the same time, it can satisfy Formula 3 or include a region satisfying Formula 3.

[0117] In Formula 3, as shown in Formula 3, the upper limit of ΔF1 can be about 30%, or can be about 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1%, and its lower limit can be about 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 10%, or 15%. ΔF1 may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0118] As shown in Formula 3, the upper limit of ΔF2 in Formula 3 can be about 30%, or can be about 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1%, and its lower limit can be about 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 10%, or 15%. ΔF2 may be in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits and greater than or equal to or greater than any of the above lower limits.

[0119] As described above, the liquid crystal layer may include a T-type liquid crystal compound, and the T-type liquid crystal compound may be a liquid crystal compound having reverse wavelength dispersion. In one example, the T-type liquid crystal compound may be a polymerizable liquid crystal compound, and when such a liquid crystal compound is polymerized, a passive liquid crystal layer may be formed.

[0120] When the liquid crystal layer is a passive liquid crystal layer, it may include a polymerization unit of a T-type liquid crystal compound which is a polymerizable liquid crystal compound. The polymerization unit means a unit formed by polymerizing or curing the polymerizable liquid crystal compound.

[0121] As used herein, the term liquid crystal compound may mean a compound comprising a portion capable of exhibiting liquid crystal properties (e.g., a liquid crystal element skeleton, etc.), and a polymerizable liquid crystal compound may mean a compound comprising one or more polymerizable functional groups and a portion capable of exhibiting liquid crystal properties. Such polymerizable liquid crystal compounds are widely known as so-called RMs (reactive liquid crystal elements). The polymerizable liquid crystal compound may be contained in a solidified layer in a polymerized form (i.e., the above-mentioned polymerization unit), which may mean that the liquid crystal compound is polymerized to form a skeleton such as a main chain or a side chain of a liquid crystal polymer in the solidified layer.

[0122] The polymerizable liquid crystal compound may be a monofunctional or multifunctional polymerizable liquid crystal compound. Here, a monofunctional polymerizable liquid crystal compound may refer to a compound having one polymerizable functional group, and a multifunctional polymerizable liquid crystal compound may refer to a compound comprising two or more polymerizable functional groups. In one example, the lower limit of the number of polymerizable functional groups in the multifunctional polymerizable liquid crystal compound may be about 2 or 3, and the upper limit thereof may be about 10, 9, 8, 7, 6, 5, 4, 3, or 2. The number of polymerizable functional groups may be in a range greater than or equal to or greater than any one of the above lower limits; in a range less than or equal to or less than any one of the above upper limits; or in a range less than or equal to or less than any one of the above upper limits, and greater than or equal to or greater than any one of the above lower limits.

[0123] When a polymerizable liquid crystal composition prepared by formulating a polymerizable liquid crystal compound with other components such as an initiator, a stabilizer and / or a non-polymerizable liquid crystal compound is cured in an aligned state on an alignment film, a cured layer (liquid crystal layer) expressing birefringence can be formed.

[0124] In order to ensure a desired geometric phase orientation, a reverse dispersion liquid crystal compound or a reverse dispersion polymerizable liquid crystal compound having a predetermined structure may be used.

[0125] It is known that the birefringence of liquid crystal compounds is mainly determined by the molecular conjugated structure, differential oscillator strength and order parameter, and in order for the liquid crystal compound to exhibit high birefringence, it requires a large electron density in the main axis direction, so most liquid crystal compounds have a highly conjugated shape in the long axis direction.

[0126] However, in order for the liquid crystal compound to exhibit reverse dispersion characteristics, it is necessary to adjust the birefringence characteristics between the long axis and the axis perpendicular to it. Therefore, most liquid crystal compounds designed to have reverse dispersion characteristics have an H-type molecular shape, and at the same time, the main axis (long axis) has a large phase difference and a small dispersion value, and the axis perpendicular to it has a small phase difference and a large dispersion value.

[0127] In the liquid crystal layer disclosed in this specification, a liquid crystal compound (T-type liquid crystal compound) in which the molecular structure or the mesogen skeleton structure is T-type is used as the liquid crystal compound. By using such a compound, a desired alignment can be effectively ensured.

[0128] As such a liquid crystal compound, a compound called a T-type liquid crystal compound can be used among known general liquid crystal compounds.

[0129] In order to more effectively obtain a desired liquid crystal layer, for example, a liquid crystal compound having a structure of the following Formula 1 may be used as the T-type liquid crystal compound.

[0130] [Chemical formula 1]

[0131]

[0132] In Chemical Formula 1, Q may be a carbon atom or a sulfur atom. Here, when Q is a sulfur atom, R2 and R3 do not exist in Chemical Formula 1.

[0133] In Chemical Formula 1, R 11 To R 14 and R3 to R5 may each independently be a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom. 11 To R 14 and R3 to R5 may each independently be a hydrogen atom or an alkyl group, or a hydrogen atom.

[0134] In Chemical Formula 1, R2 may be a substituent of the following Chemical Formula 2 or Chemical Formula 3, for example, a substituent of the following Chemical Formula 3.

[0135] [Chemical formula 2]

[0136] -A1-L1-Cy-A2-L2-R1

[0137] In Chemical Formula 2, A1 and A2 may each independently be an oxygen atom or a single bond. For example, if A1 is an oxygen atom, the oxygen atom may be connected to the skeleton of Chemical Formula 1, and if A1 is a single bond, L1 may be connected to the skeleton of Chemical Formula 1.

[0138] In Chemical Formula 2, L1 and L2 may each independently be -C(=O)-O-, -OC(=O)-, an alkylene group or an alkylidene group, Cy may be an arylene group or a cycloalkylene group, and P1 may be a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

[0139] [Chemical formula 3]

[0140]

[0141] In Chemical Formula 3, L3 and L4 may each independently be an alkylene group or an alkylidene group, and L3 is connected to the skeleton of Chemical Formula 1. In Chemical Formula 3, P2 may be a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, or a methacryloyl group, and may be, for example, a hydrogen atom, an alkyl group, an acryloyl group, or a methacryloyl group. In Chemical Formula 3, n is an arbitrary number. For example, the lower limit of n may be about 1 or 2, and the upper limit thereof may be 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1. n may be in a range greater than or equal to or greater than any of the above lower limits; in a range less than or equal to or less than any of the above upper limits; or in a range less than or equal to or less than any of the above upper limits, and greater than or equal to or greater than any of the above lower limits. In Chemical Formula 3, when n is 2 or greater, and thus there are a plurality of O-L4, the carbon numbers of L4 may be the same or different from each other.

[0142] In Chemical Formula 1, R 61 To R 65 Each of them may be independently a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, a halogen atom, a substituent of the following Chemical Formula 4, or a substituent of the following Chemical Formula 5. For example, R in Chemical Formula 1 61 To R 65 Two or more or both of may be a substituent of the following Chemical Formula 4 or a substituent of the following Chemical Formula 5, and for example may be a substituent of the following Chemical Formula 5.

[0143] For example, in Formula 1, R 61 and R 62 Any one of R 63 To R 65 Any of may be a substituent of the following Chemical Formula 4, or a substituent of the following Chemical Formula 5, and for example may be a substituent of the following Chemical Formula 5. As described above, when R of Chemical Formula 1 61 To R 65 When both of them are the substituents of Chemical Formula 4, or the substituents of Chemical Formula 5, or the substituents of Chemical Formula 5, the two substituents may be present at the para position relative to each other.

[0144] [Chemical formula 4]

[0145] -A3-L5-Cy-A4-L6-P3

[0146] In Chemical Formula 4, A3 and A4 may each independently be an oxygen atom, an alkylene group, an alkylidene group, or a single bond. For example, when A3 is an oxygen atom, an alkylene group, or an alkylidene group, A3 may be connected to the skeleton of Chemical Formula 1, and when it is a single bond, L5 may be connected to the skeleton of Chemical Formula 1.

[0147] In Chemical Formula 1, L5 and L6 may each independently be -C(=O)-O-, -OC(=O)-, an alkylene group or an alkylidene group, Cy may be an arylene group or a cycloalkylene group, and P3 may be a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group. In a suitable example, P3 may be an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

[0148] [Chemical formula 5]

[0149]

[0150] In Chemical Formula 5, A5, A6 and A7 may each independently be an oxygen atom or a single bond. For example, when A5 is an oxygen atom, an alkylene group, or an alkylidene group, A5 may be connected to the skeleton of Chemical Formula 1, and when it is a single bond, L7 may be connected to the skeleton of Chemical Formula 1.

[0151] In Chemical Formula 5, L7, L8, and L9 may each independently be -C(=O)-O-, -OC(=O)-, an alkylidene group, or an alkylene group.

[0152] In Chemical Formula 5, either Cy1 or Cy2 may be a cycloalkylene group, and the other may be an arylene group. For example, Cy1 may be an arylene group, and Cy2 may be a cycloalkylene group, or Cy1 may be a cycloalkylene group, and Cy2 may be an arylene group.

[0153] In Chemical Formula 5, P4 may be a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group, and for example, may be an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

[0154] In Chemical Formulae 1 to 5, the term single bond means that there is no independent atom at the relevant position. For example, if A2 in Chemical Formula 2 is a single bond, a structure in which A2 does not have an independent atom and Cy is directly connected to L2 can be realized.

[0155] In Chemical Formulae 1 to 5, the term alkyl or alkoxy may be a linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, which may be optionally substituted with one or more substituents.

[0156] In Chemical Formulae 1 to 5, the halogen atom may be fluorine, chlorine, or iodine.

[0157] In Chemical Formulae 1 to 5, an alkylene group is a divalent functional group formed by removing two hydrogen atoms from an alkane, which means a functional group in which hydrogen atoms are removed from different carbon atoms of the alkane, respectively. Such an alkylene group may be a linear or branched alkylene group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, which may be optionally substituted with one or more substituents.

[0158] In Chemical Formulae 1 to 5, an alkylidene group is a divalent functional group formed by removing two hydrogen atoms from an alkane, which means a functional group in which a hydrogen atom is removed from one carbon atom of an alkane. Such an alkylidene group may be a linear or branched alkylidene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, which may be optionally substituted with one or more substituents.

[0159] In Chemical Formulae 1 to 5, the arylene group may be an arylene group having 6 to 12 carbon atoms, or a phenylene group.

[0160] In Chemical Formulae 1 to 5, the cycloalkylene group may be a cycloalkylene group having 3 to 12 carbon atoms or 3 to 9 carbon atoms, or a cyclohexylene group.

[0161] In the substituent of Chemical Formula 2, A1 may be a single bond, L1 may be -C(=O)-O- or -OC(=O)-, A2 may be an oxygen atom, and L2 may be an alkylene group having 3 or more, 4 or more, or 5 or more carbon atoms. The carbon number of the alkylene group of the above L2 may be 12 or less, or 8 or less.

[0162] In one example of Chemical Formula 3, L3 and L4 may each independently be an alkylene group having 1 to 4 carbon atoms, and n may be a number in the range of 1 to 3, or a number in the range of 1 to 2, or may be 1 or 2. P2 may be a polymerizable functional group (acryloyl or methacryloyl), or may be a hydrogen atom or an alkyl group (e.g., an alkyl group having 1 to 4 carbon atoms). In addition, in the above case, when there are two or more units of [O-L4] in Chemical Formula 3, the carbon numbers of the alkylene or alkylidene groups of L4 in each unit may be the same or different from each other.

[0163] In Chemical Formula 4, A3 may be a single bond or an alkylene group having 1 to 4 carbon atoms, L5 may be -C(=O)-O- or -OC(=O)-, A4 may be an oxygen atom, and L6 may be an alkylene group having 3 or more, 4 or more, or 5 or more carbon atoms. The carbon number of the alkylene group of the above L6 may be 12 or less, or 8 or less.

[0164] In Chemical Formula 5, A5 may be an oxygen atom, L7 may be an alkylene group having 1 to 4 carbon atoms, A6 may be a single bond, L8 may be -C(=O)-O- or -OC(=O)-, A7 may be an oxygen atom, and L9 may be an alkylene group having 3 or more, 4 or more, or 5 or more carbon atoms. The carbon number of the alkylene group of the above L9 may be 12 or less, or 8 or less.

[0165] It has been determined that liquid crystal compounds can effectively satisfy desired physical properties (eg, orientation) through a unique T-type structure and a conjugated structure centered on a NN bond.

[0166] Such a liquid crystal compound is a known compound known in, for example, Korean Laid-Open Patent Publication No. 10-2018-0048837, etc.

[0167] In order to more appropriately achieve the desired orientation, as T-type liquid crystal compounds, the following can be used simultaneously: (1) a compound within the scope of Chemical Formula 1 (first liquid crystal compound), wherein R2 in Chemical Formula 1 is a substituent of Chemical Formula 2 in which P1 is a hydrogen atom, an alkyl group, or an aromatic group, or a substituent of Chemical Formula 3 in which P2 is a hydrogen atom, an alkyl group, or an aromatic group; and (2) a compound within the scope of Chemical Formula 1 (first liquid crystal compound), wherein R2 in Chemical Formula 1 is a substituent of Chemical Formula 2 in which P1 is an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group, or a substituent of Chemical Formula 3 in which P2 is an acryloyl group or a methacryloyl group.

[0168] In the first liquid crystal compound, when R2 is a substituent of Chemical Formula 2, P1 of Chemical Formula 2 may be a hydrogen atom, an alkyl group, or an aryl group, or may be a hydrogen atom or an alkyl group, or may be an alkyl group.

[0169] In the first liquid crystal compound, when R2 is a substituent of Chemical Formula 3, P2 of Chemical Formula 3 may be a hydrogen atom, an alkyl group, or an aryl group, or may be a hydrogen atom, an alkyl group, or may be an alkyl group.

[0170] In the first liquid crystal compound and the second liquid crystal compound, specific types of substituents and functional groups other than P1 of the substituent of Chemical Formula 2 or P2 of the substituent of Chemical Formula 3 are as described above.

[0171] In one example, Q of Chemical Formula 1 in the first liquid crystal compound may be a sulfur atom, and Q of Chemical Formula 1 in the second liquid crystal compound may be a carbon atom.

[0172] When using a first liquid crystal compound and a second liquid crystal compound, based on 100 parts by weight of the first liquid crystal compound, the lower limit of the weight ratio of the second liquid crystal compound can be 1 part by weight, 10 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 95 parts by weight, or about 100 parts by weight, and the upper limit thereof can be 1,000 parts by weight, 950 parts by weight, 900 parts by weight, 850 parts by weight, 800 parts by weight, 750 parts by weight, 700 parts by weight, 650 parts by weight, 600 parts by weight, 550 parts by weight, 500 parts by weight, 450 parts by weight, 400 parts by weight, 350 parts by weight, 300 parts by weight, 250 parts by weight, 200 parts by weight, 150 parts by weight, 140 parts by weight, 130 parts by weight, 120 parts by weight, 110 parts by weight, 105 parts by weight, or about 100 parts by weight. The content may be in a range greater than or equal to or greater than any one of the above lower limits; in a range less than or equal to or less than any one of the above upper limits; or in a range less than or equal to or less than any one of the above upper limits and greater than or equal to or greater than any one of the above lower limits.

[0173] If necessary, the liquid crystal layer may contain another type of reverse dispersion liquid crystal compound in addition to the T-type liquid crystal compound, or may further contain a normal dispersion liquid crystal compound. In this case, the specific type of other liquid crystal compounds that may be contained is not particularly limited.

[0174] As other liquid crystal compounds that can be applied, liquid crystal compounds known in, for example, Korean Registered Patent No. 1729819, Korean Registered Patent No. 1640670, Korean Registered Patent No. 1557202, Korean Registered Patent No. 1472187, Korean Registered Patent No. 1460862, Korean Registered Patent No. 1191124, Korean Registered Patent No. 1191125 and / or Korean Registered Patent No. 1191129 can be used, without being limited thereto.

[0175] The ratio of the normal dispersion liquid crystal compound and the like in the liquid crystal layer can be adjusted to a range capable of ensuring desired characteristics. For example, liquid crystal compounds other than the T-type liquid crystal compound can be included in a ratio of greater than 0 parts by weight to about 45 parts by weight or less relative to 100 parts by weight of the T-type liquid crystal compound.

[0176] In addition to the liquid crystal compound, the liquid crystal layer may further contain necessary additives. Examples of such additives may include known additives such as an initiator, an ultraviolet stabilizer, and / or an ultraviolet absorber.

[0177] Such a liquid crystal layer may have an adjusted thickness to be able to exhibit desired characteristics. For example, if the thickness of the liquid crystal layer is too low, the desired performance may not be obtained even when a liquid crystal compound is used. For example, the lower limit of the thickness of the liquid crystal layer may be about 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 4.0 μm, 4.1 μm, or 4.2 μm, and the upper limit thereof may be about 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4.9 μm, 4.8 μm, 4.7 μm, 4.6 μm, 4.5 μm, 4.4 μm, 4.3 μm, 4.2 μm, 4.1 μm, or 4 μm. The thickness may be in a range greater than or equal to or greater than any one of the above lower limits; or in a range less than or equal to or less than any one of the above upper limits, and greater than or equal to or greater than any one of the above lower limits.

[0178] If the optical film includes a liquid crystal layer, the optical film may further include other necessary layers. Examples of such other layers may include an alignment layer that induces alignment of a liquid crystal compound, a base material layer on which an alignment layer or a liquid crystal layer is formed, and / or a retardation film or a circular polarizing plate formed to allow circularly polarized light to be incident on the liquid crystal layer, but are not limited thereto.

[0179] This specification also discloses methods for making the optical film.

[0180] When the above liquid crystal compounds are applied to a liquid crystal layer forming a geometric phase orientation, relatively excellent orientation can be obtained, but it is difficult to achieve the desired orientation only by using liquid crystal compounds, and process conditions must be controlled, and in particular, the thickness of the liquid crystal layer must be controlled.

[0181] If necessary, the liquid crystal layer may be formed by coating a material including a liquid crystal compound (eg, a coating liquid) on a liquid crystal alignment surface, aligning the liquid crystal compound, and then curing the liquid crystal compound.

[0182] For the method of forming a liquid crystal layer disclosed in this specification, the same method as above can also be applied, but the thickness of the layer including the liquid crystal compound must be controlled in the process.

[0183] For example, a method for manufacturing an optical film includes the steps of forming a layer of a material including a liquid crystal compound on a liquid crystal alignment surface, and aligning the liquid crystal compound in a geometric phase to form a liquid crystal layer.

[0184] In this case, as the liquid crystal compound, at least the above-mentioned T-type liquid crystal compound is used.

[0185] In the manufacturing method disclosed herein, the layer of the material containing the liquid crystal compound or the liquid crystal layer in the above process must be controlled to have a thickness such that T / P of the following formula A is within a predetermined range.

[0186] [Formula A]

[0187] T / P

[0188] In Formula A, T is the thickness of the liquid crystal layer or the layer of a material containing a liquid crystal compound, and P is the pitch of the geometric phase orientation.

[0189] Here, when the geometric phase orientation is an orientation in which the above-mentioned spacing remains constant (geometric phase grating orientation, etc.), P is the spacing maintained constant, and when it is an orientation in which the above-mentioned spacing changes (geometric phase lens orientation, etc.), it is the minimum spacing among the changing spacings.

[0190] In Formula A, the same unit is used for T and P, and for example, μm is used.

[0191] For example, the upper limit of T / P in the above formula A can be about 0.45, 0.43, 0.41, 0.39, 0.37, 0.35, 0.33, 0.31, 0.29, or 0.27, and its lower limit can be about 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, or 0.34. T / P can be less than or equal to or less than any one of the above upper limits; or less than or equal to or less than any one of the above upper limits, while greater than or equal to or greater than any one of the above lower limits. When the T / P range is not met, it may become difficult to ensure the desired appropriate orientation.

[0192] The method of adjusting the thickness of the layer of the material containing the liquid crystal compound or the liquid crystal layer is not particularly limited, and for example, when applying a material such as a coating liquid containing a liquid crystal compound, the application thickness can be ensured by adjusting the thickness.

[0193] The liquid crystal layer can be formed by aligning the liquid crystal compound thus formed and then curing it, and in this case, a known curing method can be applied as the curing method.

[0194] Here, the specific type of the liquid crystal orientation surface applied is not particularly limited. Various alignment films for the orientation of liquid crystal compounds are known, and alignment films that induce geometric phase orientation are also known. Therefore, in one example, the liquid crystal orientation surface can be formed by a method of forming an alignment film on a suitable substrate, etc.

[0195] In some cases, for example, when the desired pitch is relatively small, it may be difficult to form a desired thickness in a single process while satisfying T / P of Formula A above.

[0196] In this case, the process of forming the liquid crystal layer may be repeated multiple times.

[0197] For example, a method for manufacturing an optical film may include: a first step of forming a layer of a material containing a liquid crystal compound on a liquid crystal orientation surface and orienting it to form a first sub-liquid crystal layer; and a second step of forming a layer of a material containing a liquid crystal compound on the first sub-liquid crystal layer and orienting it to form a second sub-liquid crystal layer.

[0198] Even in this case, at least a T-type liquid crystal compound can be used as the liquid crystal compound.

[0199] Furthermore, both the first step and the second step may form a layer of a material containing a liquid crystal compound or a liquid crystal layer (in this case, a sub-liquid crystal layer) so that the thickness satisfies the range of T / P of Formula A as described above.

[0200] In this method, coating, alignment, and optional curing processes are performed multiple times to form a liquid crystal layer having a desired thickness.

[0201] Therefore, the method for manufacturing an optical film includes the steps of forming a layer of a material containing a liquid crystal compound on a liquid crystal orientation surface and orienting the liquid crystal compound in a geometric phase to form a liquid crystal layer containing a liquid crystal compound oriented in a geometric phase, but the liquid crystal layer can be formed multiple times.

[0202] In the manufacturing process, the second step may be repeated two or more times. In this case, the additionally formed sub-liquid crystal layers may be sequentially formed on the sub-liquid crystal layers formed in the second step, and even in this case, each sub-liquid crystal layer is formed so that T / P of the above formula A is within the above range.

[0203] Here, the number of repetitions of the second step is not particularly limited, and, for example, it may be repeated until the sum of the thicknesses of the formed sub-liquid crystal layers becomes the final thickness of a desired liquid crystal layer.

[0204] The method of forming a liquid crystal layer or a sub-liquid crystal layer by coating a material containing a liquid crystal compound and aligning it is not particularly limited, and the liquid crystal layer or the sub-liquid crystal layer can be formed in a general manner except that the thickness of the liquid crystal layer or the sub-liquid crystal layer is controlled as described above. In addition, if necessary, in each step of forming the liquid crystal layer or the sub-liquid crystal layer, a step of fixing the alignment of the liquid crystal compound by polymerization or curing may be performed.

[0205] The present application also relates to an optical device including the optical film. The specific type of the optical device is not particularly limited, and it can be various types of optical devices that require a geometric phase lens and / or a geometric phase grating.

[0206] Representative examples of such optical devices include so-called VR (virtual reality) displays, AR (augmented reality) displays, or MR (mixed reality) displays. Therefore, the optical device can be a VR (virtual reality) display, an AR (augmented reality) display, or an MR (mixed reality) display, or a portion thereof.

[0207] The method of constructing an optical device using the optical film of the present application is not particularly limited, and if the optical film is applied, the optical device can be configured in a known manner.

[0208] In addition, the specific type of optical device is not limited to a VR (virtual reality) display, an AR (augmented reality) display, or an MR (mixed reality) display, and the optical film can be applied to various types of optical devices that require geometric phase lenses and / or geometric phase gratings.

[0209] Beneficial Effects

[0210] The present specification discloses a geometric phase optical element, a method for manufacturing the same, and uses thereof. The present specification discloses a geometric phase optical element suppressed to have no or very little wavelength dependence, a method for manufacturing the same, and uses thereof. In the present specification, a geometric phase optical element having no or little wavelength dependence by controlling the thickness of the liquid crystal layer and adjusting the manufacturing method by using a liquid crystal compound having a specific structure, a method for manufacturing the same, and uses thereof are disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0211] Figures 1 to 3 An exemplary diagram for illustrating the orientation of a geometric phase lens.

[0212] Figures 4 to 6 An exemplary diagram for illustrating the orientation of a geometric phase grating.

[0213] Figure 7 This is an exemplary diagram for explaining the linear light transmittance, etc.

[0214] Figures 8 to 10 These are polarizing micrographs of the geometric phase orientations of Examples 1 to 3, respectively.

[0215] Figures 11 to 20 These are polarizing micrographs of the geometric phase orientations of Comparative Examples 1 to 20, respectively.

[0216] Figure 21 to Figure 23 and Figure 27 to Figure 29 The results of evaluating the diffraction efficiency of the optical films of Examples 1 to 3 are shown.

[0217] Figure 24 to Figure 26 and Figure 30 to Figure 32 Results of evaluating the diffraction efficiencies of the optical films of Comparative Examples 8 to 10 are shown. DETAILED DESCRIPTION

[0218] Hereinafter, the present application will be described in detail through examples and comparative examples, but the scope of the present application is not limited to the following variable transmittance device.

[0219] Preparation Example 1.

[0220] A reactive liquid crystal compound having a structure of the following Chemical Formula A and a reactive liquid crystal compound having a structure of the following Chemical Formula B were used.

[0221] [Chemical formula A]

[0222]

[0223] [Chemical formula B]

[0224]

[0225] The reactive compound is a T-type reactive liquid crystal compound (T-type reactive liquid crystal element) known in Korean Patent Publication No. 10-2018-0048837, etc., which can be obtained from DIC or synthesized in the manner described in the above disclosure. A mixed solvent is prepared by mixing toluene (Tol) and BC (butyl carbitol) in a weight ratio of 8:2 (Tol:BC), and the reactive liquid crystal compounds of the above chemical formula A and chemical B are introduced into the mixed solvent. When introduced, the mixing ratio of the reactive liquid crystal compounds of chemical formula A and chemical B is set to 1:1 in a weight ratio (A:B), and the weight ratio of the mixed solvent and the reactive liquid crystal compound (solvent: liquid crystal) is set to 7:3. Subsequently, the coating liquid A is prepared by mixing about 5 parts by weight of an initiator (Irgacure 819, manufactured by Ciba) relative to 100 parts by weight of the reactive liquid crystal compound.

[0226] Preparation Example 2.

[0227] A coating liquid (coating liquid B) was prepared in the same manner as in Preparation Example 1, except that the weight ratio of the mixed solvent and the reactive liquid crystal compound (solvent:liquid crystal) was set to 91:9.

[0228] Example 1

[0229] Isotropic alkali-free glass (thickness: about 0.7 mm) is used as a substrate. In order to form an alignment film on the substrate, a coating liquid (Nissan, Smaple A-LC) for the alignment film is rod-coated and dried at about 65°C for about 4 minutes to form a layer (thickness: about 180 nm to 200 nm). Subsequently, the layer of the coating liquid for the alignment film is subjected to an orientation treatment to form an alignment film. For the orientation treatment, laser pattern exposure is performed to induce the orientation of the geometric phase grating. Laser pattern exposure is performed by overlapping straight light and diffuse light. The orientation treatment is performed in the manner described in the literature (Optics Express, Vol. 27, No. 3, pp. 2632 to 2642 (2019)), and an orientation treatment capable of forming a geometric phase grating with a pitch of about 15 μm is performed.

[0230] The coating liquid A of Preparation Example 1 was coated on the alignment film by bar coating, and then kept at about 100° C. for about 2 minutes, and then cooled (around about 40° C.) to align the liquid crystal compound, and then ultraviolet rays were applied at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The liquid crystal layer (geometric phase grating) is irradiated with a light amount of about 4 μm in thickness. Figure 8 The above step is the result of determining the orientation of the geometric phase grating of the liquid crystal compound by polarizing microscope. Polarizing microscope imaging was performed using an Olympus, BX53M device at a magnification of 50 times. Figure 8 It can be determined that a geometric phase grating with a pitch of about 15.84 μm has been formed through effective orientation.

[0231] Example 2

[0232] A geometric phase grating was formed in the same manner as in Example 1, except that the coating thickness of the coating liquid A of Preparation Example 1 was adjusted to form a liquid crystal layer (geometric phase grating) having a final thickness of about 4.3 μm on the alignment film. Fig. 9 The results of determining the orientation of the geometric phase grating by polarizing microscopy in the same manner as in Example 1. Fig. 9 It can be determined that a geometric phase grating with a pitch of about 15.40 μm has been formed through effective orientation.

[0233] Example 3

[0234] As a substrate, the same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 is used. In order to form an alignment film on the substrate, a coating liquid (Nissan, Smaple A-LC) for the alignment film is rod-coated and dried at about 65°C for about 4 minutes to form a layer (thickness: about 180 nm to 200 nm). Subsequently, the layer of the coating liquid for the alignment film is subjected to an orientation treatment to form an alignment film. For the orientation treatment, laser pattern exposure is performed to induce the orientation of the geometric phase lens. Laser pattern exposure is performed by overlapping straight light and diffuse light. The orientation treatment is performed in the manner described in the literature (Optics Express, Vol. 27, No. 3, pp. 2632 to 2642 (2019)), and an orientation treatment capable of forming a geometric phase lens with an end region spacing of about 1.7 μm or so is performed.

[0235] The coating liquid B of Preparation Example 2 was coated on the alignment film to a thickness of about 0.6 μm by spin coating (3,000 rpm), and then kept at about 100° C. for about 2 minutes, and then cooled (around about 40° C.) to align the liquid crystal compound, and then irradiated with ultraviolet rays at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The primary liquid crystal layer was irradiated with an amount of light of about 100 μm to form a primary liquid crystal layer (primary process). Subsequently, the coating liquid B was coated on the primary liquid crystal layer in the same manner as above to a thickness of about 0.6 μm, and then kept at about 100° C. for about 2 minutes and cooled in a nitrogen atmosphere (around about 40° C.), and then the primary liquid crystal layer was irradiated with ultraviolet rays (about 100 mJ / cm 2 ) is repeated 7 times to form a liquid crystal layer (geometric phase lens) with a final thickness of about 4.8 μm. Fig.10 In the same manner as in Example 1, the results of determining the orientation of the end region of the geometric phase lens were obtained by polarizing microscopy (Olympus, BX53M) (magnification: 100 times). Fig.10 It can be determined that a geometric phase lens with an end region spacing of about 1.67μm to 1.76μm has been formed through effective orientation.

[0236] Comparative Example 1

[0237] An alignment film was formed in the same manner as in Example 3 on the same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 as a substrate.

[0238] Subsequently, a liquid crystal layer was formed on the alignment film. As a coating liquid applied to form the liquid crystal layer, a coating liquid (Merck, M2032) containing an H-type reverse dispersion reactive liquid crystal compound (H-type reactive liquid crystal element) obtained from Merck was used. The coating liquid was applied to the alignment film in a bar coating manner to a thickness of about 0.9 μm, maintained at about 100° C. for about 2 minutes, and then cooled (at about 40° C.) to align the liquid crystal compound. Fig.11 The results of determining the orientation using a polarizing microscope (Olympus, BX53M) (magnification: 100 times). Fig.11 It can be confirmed that when the H-type reverse dispersion reactive liquid crystal compound (H-type reactive mesogen) has been applied, alignment is not effectively achieved.

[0239] Comparative Example 2

[0240] The same process as in Comparative Example 2 was performed except that the coating thickness was adjusted to about 0.6 μm. Fig.12 The orientation was determined by polarizing microscopy. Fig.12 It can be confirmed that when the H-type reverse dispersion reactive liquid crystal compound (H-type reactive mesogen) has been applied, alignment is not effectively achieved even if the thickness is further reduced.

[0241] Comparative Example 3

[0242] As a substrate, the same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 was used. An alignment film was formed on the substrate in the same manner as in Example 1, but the alignment film was allowed to form a geometric phase grating with a pitch of about 2.5 μm.

[0243] The coating liquid applied in Comparative Example 1 was coated on the alignment film to a thickness of about 0.6 μm by bar coating, and then kept at about 100° C. for about 2 minutes, cooled (around about 40° C.) to align the liquid crystal compound, and then irradiated with ultraviolet rays at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The primary liquid crystal layer is irradiated with an amount of light to form a primary liquid crystal layer (primary process). As a result of determining the orientation of the liquid crystal compound in the primary process, it can be determined that the orientation of the liquid crystal compound is achieved in the primary process. Subsequently, the coating liquid is further coated on the primary liquid crystal layer to a thickness of about 0.6 μm in the same manner as in the primary process, and the orientation is determined after the orientation treatment. Fig.13 As a result, and in this case, it can be determined that the alignment of the liquid crystal compound is not effectively achieved.

[0244] Comparative Example 4

[0245] The same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 was used as a substrate, and an alignment film was formed in the same manner as in Comparative Example 3.

[0246] The coating liquid applied in Comparative Example 1 was coated on the alignment film in a bar coating manner to a thickness of about 1.2 μm, and then kept at about 100° C. for about 2 minutes, cooled (around about 40° C.) to align the liquid crystal compound, and then irradiated with ultraviolet rays at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The result of determining the orientation of the liquid crystal compound in the above process is as follows: Fig.14 As shown, and in this case, it can be determined that the alignment of the liquid crystal compound is not effectively achieved.

[0247] Comparative Example 5

[0248] The same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 was used as a substrate, and an alignment film was formed in the same manner as in Example 1.

[0249] The coating liquid applied in Comparative Example 1 was coated on the alignment film in a bar coating manner to a thickness of about 1.6 μm, and then kept at about 100° C. for about 2 minutes, cooled (around about 40° C.) to align the liquid crystal compound, and then irradiated with ultraviolet rays at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The result of determining the orientation of the liquid crystal compound in the above process is as follows: Fig.15 As shown, and in this case, it can be determined that the alignment of the liquid crystal compound is not effectively achieved.

[0250] Comparative Example 6

[0251] The same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 was used as a substrate, and an alignment film was formed in the same manner as in Example 1.

[0252] The coating liquid applied in Comparative Example 1 was coated on the alignment film in a bar coating manner to a thickness of about 1.2 μm, and then kept at about 100° C. for about 2 minutes, cooled (around about 40° C.) to align the liquid crystal compound, and then irradiated with ultraviolet rays at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The result of determining the orientation of the liquid crystal compound in the above process is as follows: Fig.16 As shown, and in this case, it can be determined that the alignment of the liquid crystal compound is not effectively achieved.

[0253] Comparative Example 7

[0254] As a substrate, the same isotropic alkali-free glass (thickness: about 0.7 mm) as in Example 1 was used. An alignment film was formed on the substrate in the same manner as in Example 1, but the alignment film was formed to form a geometric phase grating with a pitch of about 2.5 μm. The coating liquid B of Preparation Example 2 was coated on the alignment film in the same manner as in Example 3 to a thickness of about 1.2 μm, and then after being kept at about 100° C. for about 2 minutes, it was cooled (in the vicinity of about 40° C.) to align the liquid crystal compound, and ultraviolet rays were irradiated at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The result of determining the orientation of the liquid crystal compound in the above process is as follows: Fig.17 As shown, and in this case, it can be determined that the alignment of the liquid crystal compound is not effectively achieved.

[0255] Comparative Example 8

[0256] An alignment film was formed on a substrate in the same manner as in Example 1. The coating liquid A of Preparation Example 1 was coated on the alignment film in the same manner as in Example 1, and then after being kept at about 100° C. for about 2 minutes, it was cooled (around about 40° C.) to align the liquid crystal compound, and then the liquid crystal compound was irradiated by a Fusion UV system at about 100 mJ / cm 2 Ultraviolet rays are irradiated with a light amount of to form a liquid crystal layer (geometric phase grating) with a thickness of about 1.6 μm. Fig.18 To determine the result of the orientation of the liquid crystal compound, and from Fig.18 It can be determined that a geometric phase grating with a pitch of about 14.96μm has been formed through effective orientation.

[0257] Comparative Example 9

[0258] An alignment film was formed on a substrate in the same manner as in Example 1. The coating liquid A of Preparation Example 1 was coated on the alignment film in the same manner as in Example 1, and then after being kept at about 100° C. for about 2 minutes, it was cooled (in the vicinity of about 40° C.) to align the liquid crystal compound, and then ultraviolet rays were irradiated at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The liquid crystal layer (geometric phase grating) is irradiated with a light amount of about 2.4 μm in thickness. Fig.19 To determine the result of the orientation of the liquid crystal compound, and from Fig.19 It can be determined that a geometric phase grating with a pitch of about 15.40 μm has been formed through effective alignment.

[0259] Comparative Example 10

[0260] An alignment film was formed on a substrate in the same manner as in Example 1. The coating liquid A of Preparation Example 1 was coated on the alignment film in the same manner as in Example 1, and then after being kept at about 100° C. for about 2 minutes, it was cooled (in the vicinity of about 40° C.) to align the liquid crystal compound, and then ultraviolet rays were irradiated at about 100 mJ / cm by a Fusion UV system under a nitrogen atmosphere. 2 The liquid crystal layer (geometric phase grating) is irradiated with a light amount of about 3.1 μm in thickness. Fig. 20 To determine the result of the orientation of the liquid crystal compound, and from Fig. 20 It can be determined that a geometric phase grating with a pitch of about 15.40 μm has been formed through effective alignment.

[0261] Test Example 1. Evaluation of R(450) / R(550)

[0262] The sample for evaluating R(450) / R(550) was prepared in the following manner. A coating liquid for alignment film (Smaple A-LC, manufactured by Nissan) was bar-coated on an isotropic alkali-free glass (thickness: about 0.7 mm) and dried at about 65°C for about 4 minutes to form a layer with a thickness of about 2 μm. Subsequently, ultraviolet rays (Fusion UV system, 100 mJ / cm2) linearly polarized using a WGP (wire grid polarizer) were used. 2 ) is irradiated on the layer to form an alignment film.

[0263] The coating liquids of Preparation Example 1 and Preparation Example 2 were each applied on the alignment layer in the same manner as in Example 1 to form a liquid crystal layer.

[0264] For the liquid crystal layer, R(450) and R(550) were each measured using an in-plane phase difference measurement device (Axoscan equipment) to evaluate R(450) / R(550).

[0265] As a result of determination in the above manner, R(450) / R(550) of the liquid crystal layer formed with the coating liquid A of Preparation Example 1 was about 0.79, and R(450) / R(550) of the liquid crystal layer formed with the coating liquid B of Preparation Example 3 was about 0.79. In addition, when the coating liquid containing the H-type reactive liquid crystal compound obtained from Merck used in Comparative Example was applied, R(450) / R(550) was about 0.73.

[0266] Test Example 2. Linear Light Transmittance Spectrum Evaluation

[0267] The linear transmittance spectra of non-polarized light of the optical films of Examples and Comparative Examples were evaluated in the following manner: The liquid crystal layer of the optical film was irradiated with non-polarized light using an Ocean Optics spectrometer (HR4000), and the spectrum was determined by evaluating the linear transmittance.

[0268] As in Figure 7 In the embodiment, non-polarized light L1 is irradiated for each wavelength in a direction parallel to the normal direction of the liquid crystal layer 100, and the linear light L E1 In the transmittance evaluation, the distance between the light source irradiating the light L1 and the liquid crystal layer 100 is set to about 20 mm, and the linear light L1 is measured at a distance of 100 mm from the liquid crystal layer 100 by a detector having a 1 mm light receiving component. E1 The transmittance.

[0269] Figure 21 to Figure 23 are the evaluation results of Examples 1 to 3, and Figure 24 to Figure 26 The results of Comparative Examples 8 to 10 are shown respectively. The above evaluation was not performed on Comparative Examples 1 to 7 in which the liquid crystal compound was not properly aligned. Figure 21 to Figure 26 , the x-axis represents wavelength, and the y-axis represents linear light transmittance.

[0270] In the following Table 1, the respective linear light transmittance and linear light intensity are summarized and described when the above method has been applied thereto. In the following Table 1, the transmittance is the linear light transmittance for each reference wavelength, where the unit is %, and the intensity is the linear light intensity for each reference wavelength.

[0271] [Table 1]

[0272]

[0273] Test Example 3. Linear Light Intensity Spectrum Evaluation

[0274] The intensity spectrum of right-handed circularly polarized linear light of the optical films of the embodiments and comparative examples was evaluated in the following manner. The liquid crystal layer of the optical film was irradiated with right-handed circularly polarized light using a spectrometer of AxoScan, and the spectrum was determined by evaluating the linear light intensity (unit: cd). This method was performed in the same manner as in Test Example 1, except that the irradiation light was changed from non-polarized light to right-handed circularly polarized light.

[0275] Figure 27 to Figure 29 are the evaluation results of Examples 1 to 3, and Figure 30 to Figure 32 The results of Comparative Examples 8 to 10 are shown respectively. The above evaluation was not performed on Comparative Examples 1 to 7 in which the liquid crystal compound was not properly aligned. Figures 27 to 32 , the x-axis represents wavelength, and the y-axis represents linear light intensity.

[0276] In the following Table 2, the respective straight light transmittances and straight light intensities are summarized and described when the above method has been applied thereto. In the following Table 2, the transmittance is the straight light transmittance for each reference wavelength, where the unit is %, and the intensity is the straight light intensity for each reference wavelength.

[0277] [Table 2]

[0278]

Claims

1. An optical film comprising a liquid crystal layer, wherein the liquid crystal layer comprises a T-type liquid crystal compound, wherein the T-type liquid crystal compound is aligned in a geometric phase, The liquid crystal layer satisfies at least one of the following conditions of Formula 1 and Formula 2: [Formula 1] T 平均 ≤5% and SD T ≤1.5 [Formula 2] I 平均 ≤0.1cd and SD I ≤0.025 Where T 平均 T B , T G and T R Mean, SD T T B , T G and T R The standard deviation of B is the linear light transmittance of the liquid crystal layer for non-polarized light with a wavelength of 450 nm, T G is the linear light transmittance of the liquid crystal layer for non-polarized light with a wavelength of 550 nm, and T R is the linear light transmittance of the non-polarized light with a wavelength of 610 nm relative to the liquid crystal layer; and 平均 For I B ,I G and I R Mean, SD I For I B ,I G and I R The standard deviation of B is the linear light intensity of circularly polarized light with a wavelength of 450nm relative to the liquid crystal layer, I G is the linear light intensity of circularly polarized light with a wavelength of 550 nm relative to the liquid crystal layer, and I R is the linear light intensity of circularly polarized light with a wavelength of 610 nm relative to the liquid crystal layer. 2 . The optical film according to claim 1 , wherein the liquid crystal layer satisfies both the conditions of Formula 1 and the conditions of Formula 2. 3 .

3. The optical film according to claim 1, wherein the liquid crystal layer satisfies the following formula 3: [Formula 3] ΔF1 and ΔF2 ≤ 30% Where ΔF1 is the absolute value of F1 according to the following equation 4, and ΔF2 is the absolute value of F2 according to the following equation 5: [Formula 4] F1=100×(θ R -θ G ) / θ G [Formula 5] F2=100×(θ B -θ G ) / θ G in, θ R is the refraction angle of the region satisfying the following equation 6, θ G is the refraction angle of the region satisfying the following equation 7, and θ B The refraction angle of the region satisfying the following equation 8, [Formula 6] sinth R =610 / L [Formula 7] sinth G =550 / L [Formula 8] sinth B =450 / L Wherein, Λ is the spacing of the geometric phase orientation of the region (unit: nm).

4. The optical film according to claim 1, wherein the orientation of the liquid crystal compound is a geometric phase lens orientation, wherein the geometric phase lens orientation has an azimuth angle that satisfies the following formula 9 and changes along at least one direction in the plane direction of the liquid crystal layer: [Formula 9] θ(r){π×r 2 } / {2×f×λ} in, θ(r) is the azimuth angle of the liquid crystal compound in a region of the liquid crystal layer spaced a distance r (unit: mm) from the center of the geometric phase lens orientation, r is the distance, f is the focal length of the geometric phase lens orientation, and λ is the wavelength of the incident light.

5. An optical film as claimed in claim 4, wherein the azimuthal variation in the geometric phase lens orientation occurs in a radial direction.

6. The optical film according to claim 1, wherein the orientation of the liquid crystal compound is a geometric phase grating orientation having an azimuth angle that changes along any one of the plane directions of the liquid crystal layer and having a constant pitch defined by the changing azimuth angle. 7 . The optical film according to claim 6 , wherein the geometric phase grating is oriented such that the azimuth angle is maintained along a plane direction perpendicular to a direction in which the varying azimuth angle is determined. 8 . The optical film of claim 6 , wherein a pitch defined by the varying azimuth angles is in a range of 0.1 μm to 20 μm. 9 . The optical film according to claim 1 , wherein the liquid crystal layer has a thickness of 3.5 μm or more.

10. The optical film according to claim 1, wherein a ratio (R(450) / R(550)) of the in-plane retardation (R(450)) of the T-type liquid crystal compound for light having a wavelength of 450 nm to the in-plane retardation (R(550)) for light having a wavelength of 550 nm is in the range of 0.6 to 0.

99.

11. The optical film according to claim 1, wherein the T-type liquid crystal compound is represented by the following Formula 1: [Chemical formula 1] in, Q is a carbon atom or a sulfur atom, and when Q is a sulfur atom, R2 and R3 are absent, R 11 To R 14 and R3 to R5 are each independently a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom, R2 is a substituent of the following Chemical Formula 2 or Chemical Formula 3, and R 61 To R 65 are each independently a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, a halogen atom, a substituent of the following Chemical Formula 4, or a substituent of the following Chemical Formula 5, but R 61 To R 65 Two or more of are substituents of the following Chemical Formula 4, or substituents of the following Chemical Formula 5; [Chemical formula 2] -A1-L1-Cy-A2-L2-P1 wherein A1 and A2 are each independently an oxygen atom or a single bond, and L1 and L2 are each independently -C(=O)-O-, -OC(=O)-, an alkylene group, or an alkylidene group, Cy is an arylene group or a cycloalkylene group, and P1 is a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group; [Chemical formula 3] wherein L3 and L4 are each independently an alkylene group or an alkylidene group, P2 is a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, or a methacryloyl group, and n is a number in the range of 1 to 10; [Chemical formula 4] -A3-L5-Cy-A4-L6-P3 wherein A3 and A4 are each independently an oxygen atom, an alkylene group, an alkylidene group, or a single bond, L5 and L6 are each independently -C(=O)-O-, -OC(=O)-, an alkylene group, or an alkylidene group, Cy is an arylene group or a cycloalkylene group, and P3 is a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group; [Chemical formula 5] wherein A5, A6 and A7 are each independently an oxygen atom or a single bond, L7, L8 and L9 are each independently -C(=O)-O-, -OC(=O)-, an alkylidene group or an alkylene group, either Cy1 and Cy2 is a cycloalkylene group, and the other is an arylene group, and P4 is a hydrogen atom, an alkyl group, an aryl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

12. The optical film according to claim 11, wherein The liquid crystal layer includes the following as T-type liquid crystal compounds: a compound in which R2 of Chemical Formula 1 is a substituent of Chemical Formula 2 in which P1 is a hydrogen atom, an alkyl group or an aryl group, or a compound in which R2 of Chemical Formula 1 is a substituent of Chemical Formula 3 in which P2 is a hydrogen atom, an alkyl group or an aryl group; and a compound in which R2 of Chemical Formula 1 is a substituent of Chemical Formula 2 in which P1 is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, or a compound in which R2 of Chemical Formula 1 is a substituent of Chemical Formula 3 in which P2 is an acryloyl group or a methacryloyl group.

13. A method for manufacturing an optical film, comprising: forming a layer of a material including a liquid crystal compound on the liquid crystal alignment surface, and aligning the liquid crystal compound in a geometric phase to form a liquid crystal layer, wherein the liquid crystal compound is a T-type liquid crystal compound, and The layer of the material containing a liquid crystal compound or the liquid crystal layer is formed to have a thickness satisfying the following Formula 10: [Formula 10] T / P≤0.45 Wherein, T is the thickness of the liquid crystal layer or the layer of the material containing the liquid crystal compound, and P is the pitch of the geometric phase orientation.

14. A method for manufacturing an optical film, comprising: forming a layer of a material including a liquid crystal compound on a liquid crystal alignment surface, and aligning the liquid crystal compound in a geometric phase to form a liquid crystal layer, The method comprises: A first step of forming a layer of the material containing the liquid crystal compound on the liquid crystal alignment surface and aligning the material to form a first sub-liquid crystal layer; and a second step of forming a layer of the material containing the liquid crystal compound on the first sub-liquid crystal layer and aligning the material to form a second sub-liquid crystal layer, wherein the liquid crystal compound is a T-type liquid crystal compound, and The layer or sub-liquid crystal layer of the material containing the liquid crystal compound is formed to have a thickness satisfying the following formula 10: [Formula 10] T / P≤0.45 Wherein, T is the thickness of the sub-liquid crystal layer or the layer of the material containing the liquid crystal compound, and P is the pitch of the geometric phase orientation.

15. The method according to claim 14, wherein the second step is repeated two or more times.

16. An optical device comprising the optical film according to any one of claims 1 to 12.

17. The optical device according to claim 16, wherein the optical device is a virtual reality display, an augmented reality display, or a mixed reality display, or a part thereof.

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