Depolarization element and near-eye display

Abstract

The purpose of the present invention is to provide a depolarization element having depolarization characteristics that prevent occurrence of color unevenness even when an image display device is observed through a near-eye display having polarization characteristics. A depolarization element according to the present invention has a first retardation layer and a second retardation layer. The in-plane retardation of the first retardation layer at a wavelength of 550 nm is from 3000 nm to 100000 nm. The second retardation layer is a patterned retardation layer in which at least one of an in-plane slow-axis orientation and a phase difference has a distribution.

Description

Polarization depolarization element and near-eye display

[0001] This invention relates to a polarizing element and a near-eye display.

[0002] Conventionally, phase difference films such as quarter-wave plates have been used to impart optical functions to image display devices. For example, when an observer wearing polarized sunglasses views an image displayed on an image display device that uses a polarizing plate on the light-emitting side, the screen appears completely black, which is a problem (blackout). In response to this, it is known that by installing a quarter-wave plate on the light-emitting side of an image display device such that the angle between the absorption axis of the polarizer of the polarizing plate of the image display device and the slow axis of the quarter-wave plate is approximately 45 degrees, the emitted light is made approximately circularly polarized, thereby preventing blackout (Patent Document 1).

[0003] Japanese Patent Publication No. 2019-174636

[0004] Polarized sunglasses absorb one type of linearly polarized light and transmit the other type of linearly polarized light whose polarization direction is perpendicular to it. Therefore, blackout can be suppressed by converting the light emitted from an image display device into circularly polarized light. On the other hand, near-eye displays such as AR (Augmented Reality) glasses, which have polarization properties, are also known as glasses that absorb or reflect a predetermined type of polarization. It has been found that when viewing an image display device while wearing such a near-eye display, blackout or color unevenness may occur. This is thought to be due to the interaction between the polarization state of the light emitted by the image display device and the polarization properties of the near-eye display.

[0005] Therefore, the present invention aims to provide a depolarizing element having depolarizing properties that prevent color unevenness even when an image display device is observed with a near-eye display having polarization properties attached. The present invention also aims to provide a near-eye display that uses this depolarizing element.

[0006] The inventors of the present invention have conducted extensive research on the above-mentioned problems and have found that the above problems can be achieved with the following configuration.

[0007] [1] A depolarizing element comprising a first phase difference layer and a second phase difference layer, wherein the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is from 3000 nm to 100000 nm, and the second phase difference layer is a patterned phase difference layer having a distribution of at least one of the slow phase axis orientation and phase difference in the plane. [2] The depolarizing element according to [1], wherein the second phase difference layer is a patterned phase difference layer having a distribution of the slow phase axis orientation in the plane. [3] The depolarizing element according to [2], wherein the patterned phase difference layer has regions 1 and 2 with different slow phase axis orientations, and regions 1 and 2 are arranged alternately in a stripe pattern. [4] The depolarizing element according to [2] or [3], wherein the phase difference of the second phase difference layer at a wavelength of 550 nm is λ / 4. [5] The depolarizing element according to [1], wherein the second phase difference layer is a patterned phase difference layer having a distribution of phase difference in the plane. [6] The depolarizing element according to [5], wherein the pattern phase difference layer has regions 1 and 2 with different phase differences, and regions 1 and 2 are alternately arranged in a stripe pattern. [7] The depolarizing element according to [6], wherein in the second phase difference layer, the difference between the phase difference of region 1 at a wavelength of 550 nm and the phase difference of region 2 at a wavelength of 550 nm is λ / 2. [8] A depolarizing element having a phase difference layer, wherein the in-plane retardation of the phase difference layer at a wavelength of 550 nm is from 3000 nm to 100000 nm, and the phase difference layer is a pattern phase difference layer having a distribution of phase differences in the plane. [9] The depolarizing element according to [8], wherein the pattern phase difference layer has regions 1 and 2 with different phase differences, and regions 1 and 2 are alternately arranged in a stripe pattern.

[10] The depolarization element according to [9], wherein in the phase difference layer, the difference between the phase difference at a wavelength of 550 nm in region 1 and the phase difference at a wavelength of 550 nm in region 2 is λ / 2.

[11] A near-eye display having the depolarization element according to any one of [1] to

[10] .

[12] A near-eye display comprising the depolarization element according to any one of [1] to

[10] and a polarizer, wherein the polarizer is positioned on the user side when the user wears the near-eye display.

[0008] According to the present invention, it is possible to provide a depolarizing element having depolarizing properties that prevent color unevenness even when an image display device is observed with a near-eye display having polarization properties attached. Furthermore, according to the present invention, it is possible to provide a near-eye display using this depolarizing element.

[0009] This is a schematic diagram showing an example of a polarization depolarization element of the present invention, representing a polarization depolarization element having a first phase difference layer and a second phase difference layer. This is a schematic diagram showing an example of a second phase difference layer in a polarization depolarization element of the present invention, representing a pattern phase difference layer having alternating regions 1 and 2, where the lagging axis orientations of regions 1 and 2 are different. This is a schematic diagram showing an example of a second phase difference layer in a polarization depolarization element of the present invention, representing a pattern phase difference layer having alternating regions 1 and 2, where the phase difference between regions 1 and 2 is different. This is a schematic diagram showing an example of a phase difference layer in a polarization depolarization element of the present invention, representing a pattern phase difference layer having alternating regions 1 and 2, where the phase difference between regions 1 and 2 is different.

[0010] The present invention will now be described in detail. The following descriptions of constituent elements may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In this specification, numerical ranges expressed using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits.

[0011] In this specification, "orthogonal" does not mean exactly 90°, but rather 90°±10°, preferably 90°±5°. Similarly, "parallel" does not mean exactly 0°, but rather 0°±10°, preferably 0°±5°. Furthermore, "45°" does not mean exactly 45°, but rather 45°±10°, preferably 45°±5°.

[0012] In this specification, "absorption axis" refers to the polarization direction in which absorbance is maximum when linearly polarized light is incident on the surface. "Reflection axis" refers to the polarization direction in which reflectance is maximum when linearly polarized light is incident on the surface. "Transmission axis" refers to the direction perpendicular to the absorption axis or reflection axis in the surface. Furthermore, "latent axis" refers to the direction in the surface where refractive index is maximum. In this specification, phase difference refers to in-plane retardation unless otherwise specified, and is denoted as Re(λ). Here, Re(λ) represents the in-plane retardation at wavelength λ, and unless otherwise specified, wavelength λ is 550 nm. The retardation in the thickness direction at wavelength λ is denoted as Rth(λ) in this specification. Unless otherwise specified, wavelength λ is 550 nm. Re(λ) and Rth(λ) can be measured at wavelength λ using an AxoScan OPMF-1 (manufactured by Axometrics). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d (μm)) into AxoScan, the following can be calculated: Re(λ) = R0(λ) and Rth(λ) = ((nx + ny) / 2 - nz) × d in the slow phase axis direction (°).

[0013] The polarization-depolarizing element of the present invention will be described below.

[0014] The depolarization element of the present invention comprises a first phase difference layer and a second phase difference layer, wherein the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is from 3,000 nm to 100,000 nm, and the second phase difference layer is a patterned phase difference layer having a distribution of at least one of the slow axis orientation and phase difference in the plane. Preferred embodiments of the depolarization element will be described below. One embodiment of the depolarization element of the present invention has a first phase difference layer and a second phase difference layer, as conceptually shown in Figure 1. The first phase difference layer has a high retardation value of 3,000 nm to 100,000 nm in-plane retardation at a wavelength of 550 nm. The depolarization mechanism by the phase difference layer having high retardation is due to the large change in retardation with respect to wavelength changes. As a result, the polarization state of transmitted light changes significantly with respect to wavelength changes. Consider a configuration in which a phase difference layer having high retardation is placed between a polarizing element and an image display device. When the spectral radiance spectrum of an image display device is measured through a polarizing element, the spectral radiance becomes zero at certain wavelengths because the polarization characteristics cause absorption by the polarizing element. However, at different wavelengths in the vicinity, the polarization characteristics cause transmission through the polarizing element, resulting in high spectral radiance. This mechanism prevents all wavelengths of light from being cut off, allowing some wavelengths to pass through, thus suppressing blackout.

[0015] On the other hand, this mechanism can cause color unevenness when the spectral radiance spectrum of an image display device has a narrow-band spectral light at a certain wavelength. In the transmission spectrum obtained by the combination of the image display device, the first phase difference layer, and the polarizing element, if the wavelength range with low transmittance exactly overlaps with this narrow-band spectral light, this narrow-band spectral light does not reach the human eye. Conversely, if the wavelength range with high transmittance exactly overlaps with this narrow-band spectral light, this narrow-band spectral light reaches the human eye. The transmission characteristics of the combination of the image display device, the first phase difference layer, and the polarizing element are mainly determined by the retardation value in that direction. If the difference in retardation between the normal direction and the oblique direction is large, the transmission characteristics of the combination of the image display device, the first phase difference layer, and the polarizing element will change with respect to the angle, causing the color to change with the angle and appearing as color unevenness.

[0016] One aspect of the depolarizing element of the present invention (first embodiment) further improves this color unevenness by having a second phase difference layer. Preferably, the second phase difference layer is a patterned phase difference layer in which the slow axis orientation is distributed within the plane. This makes it possible to have a characteristic in which the color changes within the plane, in addition to the characteristic in which the color changes with angle. When an image display device is observed through a depolarizing element with such characteristics, the color unevenness that occurs with respect to angle changes is averaged out in the eye, thereby reducing color unevenness.

[0017] A second embodiment of the depolarizing element of the present invention has a first phase difference layer and a second phase difference layer, wherein the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is preferably from 3,000 nm to 100,000 nm, and the second phase difference layer is preferably a patterned phase difference layer having an in-plane phase difference distribution. By having a second phase difference layer in addition to the first phase difference layer, it is possible to provide a characteristic of color change within the plane in addition to the characteristic of color change depending on the angle. When an image display device is observed through a depolarizing element with such characteristics, it is possible to reduce color unevenness by averaging out the color unevenness that occurs with respect to angle changes in the eye.

[0018] A third aspect (third embodiment) of the depolarizing element of the present invention is a patterned phase difference layer having a high in-plane retardation value from 3,000 nm to 100,000 nm at a wavelength of 550 nm, and having a phase difference distribution in the plane. This makes it possible to give the image a characteristic of color changing in the plane, in addition to the characteristic of color changing with angle. When an image display device is observed through a depolarizing element with such characteristics, the color unevenness that occurs with respect to angle changes is averaged out in the eye, thereby reducing color unevenness.

[0019] In addition to the above embodiments, a preferred embodiment is also one in which the depolarization element has a first phase difference layer and a second phase difference layer, the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is from 3,000 nm to 100,000 nm, and the second phase difference layer is a patterned phase difference layer having an in-plane phase difference distribution and a slow phase axis orientation distribution.

[0020] The depolarization elements of the present invention are suitable for applications in which an image display device is observed while wearing a near-eye display having polarization characteristics, such as AR glasses. By observing the display image of the image display device with a near-eye display having the depolarization elements of the present invention, it is possible to achieve image display with suppressed color unevenness. Color unevenness is thought to occur due to the interaction between the polarization state of the light emitted by the image display device and the polarization characteristics of the AR glasses. Since the depolarization elements of the present invention can effectively depolarize the incident light, the occurrence of color unevenness can be suppressed. The depolarization elements of the present invention, having such characteristics, are useful in fields where advanced optical performance utilizing polarization, such as AR glasses, is required.

[0021] Preferred embodiments of the components of the present invention will be described below.

[0022] [First Phase Difference Layer] The first and second embodiments described above include a first phase difference layer. The first phase difference layer will be described below.

[0023] <In-plane retardation in the normal direction of the first phase difference layer> The first phase difference layer included in the depolarization element of the present invention is preferably a high retardation film having a phase difference of several times or more the wavelength of light in the visible range. The in-plane retardation of the first phase difference layer at a wavelength of 550 nm is 3,000 nm to 100,000 nm, preferably 5,000 nm to 50,000 nm, and more preferably 7,000 nm to 20,000 nm. If the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is 3,000 nm or more, the depolarization ability due to wavelength scrambling is increased, which can suppress color unevenness and blackout. On the other hand, if the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is 100,000 nm or less, it can suppress a decrease in transmittance and deterioration of transmitted image clarity due to the thickness of the phase difference layer being too thick. The in-plane retardation of the first phase difference layer at a wavelength of 550 nm is the in-plane retardation measured when light is incident on the first phase difference layer from the direction normal to the first phase difference layer. Here, the retardation of the first phase difference layer can be adjusted by the formation conditions of the phase difference layer, the forming material, the film thickness of the phase difference layer, and the stacking of multiple phase difference layers.

[0024] <Configuration of the First Phase Difference Layer> The first phase difference layer may consist of only one layer, or it may have two or more phase difference layers. There is no limit to the number of phase difference layers in the first phase difference layer, but it is preferable to have fewer than 20 layers, more preferably fewer than 10 layers, even more preferably fewer than 6 layers, and most preferably fewer than 3 layers, in order to reduce interface reflection and obtain high transmitted image clarity.

[0025] By stacking multiple phase difference layers, high retardation values ​​can be obtained while precisely controlling retardation in the oblique direction, thereby achieving a suitable depolarization effect for light sources with various polarization states and spectra. In other words, in a configuration with multiple stacked phase difference layers, as described above, each phase difference layer can have a different retardation. Therefore, by adjusting the film thickness of each layer according to the retardation of the combined phase difference layers, the difference between the retardation in the normal direction and the retardation in the oblique direction of the depolarization element can be reduced, further suppressing blackout and color unevenness.

[0026] As described above, if the first phase difference layer has multiple phase difference layers, there is no limit to the number of phase difference layers as long as the above retardation is satisfied. Here, in terms of the depolarization function, a larger number of stacked phase difference layers is preferable because it results in higher retardation and thus better blackout suppression. On the other hand, in terms of the brightness of the image observed through the depolarization element and the clarity of the transmitted image, a smaller number of stacked phase difference layers is advantageous.

[0027] <Optical Properties of Laminated Phase Difference Layers> It is preferable that each phase difference layer in a laminated phase difference layer be designed to exhibit a desired retardation at a specific wavelength. This effectively eliminates the polarization state of light, regardless of the polarization state of the incident light. This retardation can be adjusted by known methods, such as the thickness of the film and the degree of optical anisotropy (birefringence) of the optical anisotropic material.

[0028] <Material of the First Phase Difference Layer> There are no particular restrictions on the composition and material of the film that satisfies the optical properties of the first phase difference layer used in the depolarization element of the present invention. The materials constituting the first phase difference layer will be described below.

[0029] As the material constituting the first phase difference layer, for example, a thermoplastic resin (e.g., polyester resin or polycarbonate resin) that is excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be used as the main component. In this specification, the main component refers to a material that constitutes 50% or more by mass of the first phase difference layer relative to the total mass of the first phase difference layer.

[0030] The first phase difference layer may contain one or more suitable additives in addition to the thermoplastic resin material described above. Examples of additives include ultraviolet absorbers, particles, lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, lightfastness agents, impact resistance modifiers, lubricants, dyes, and pigments. The content of the thermoplastic resin in the first phase difference layer is preferably 50 to 100% by mass, more preferably 50 to 99% by mass, even more preferably 60 to 98% by mass, and particularly preferably 70 to 97% by mass, based on the total mass of the first phase difference layer. When the content of the thermoplastic resin in the first phase difference layer is 50% by mass or more, the high transparency and other properties inherent to the thermoplastic resin can be fully expressed.

[0031] The first phase difference layer may be a single-layer film or a multilayer film. Furthermore, both or one side of these single-layer or multilayer films may be surface-treated. This surface treatment may include surface modification by corona treatment, saponification, heat treatment, ultraviolet irradiation, electron beam irradiation, etc., or thin film formation by coating or vapor deposition of polymers, metal compounds, etc. Additionally, to improve adhesion with other components, an easy-adhesion layer, as described later, may be formed.

[0032] The first phase difference layer is preferably a polyester film mainly composed of polyester resin. That is, in the polyester film, the polyester resin content is 50% by mass or more relative to the total mass of the first phase difference layer. Furthermore, it is preferable that the first phase difference layer is a polyester film stretched in at least one axial direction. Examples of polyester resins include polyethylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, and 1,4-cyclohexanedimethylene terephthalate, and two or more of these may be used as needed. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferably used. From the viewpoint of material cost, it is more preferable to use polyethylene terephthalate.

[0033] Polyethylene terephthalate is a polyester having structural units derived from terephthalic acid as a dicarboxylic acid component and structural units derived from ethylene glycol as a diol component, preferably with 80 mol% or more of the total repeating units being ethylene terephthalate, and may also contain structural units derived from other copolymer components. Examples of other copolymer components include dicarboxylic acid components such as isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxyphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfisoisophthalic acid, and 1,4-dicarboxycyclohexane, and diol components such as propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Two or more of these dicarboxylic acid and diol components can be used in combination as needed. Furthermore, it is possible to use oxycarboxylic acids such as p-oxybenzoic acid in combination with the above-mentioned carboxylic acid and diol components. Other copolymer components may include dicarboxylic acid and / or diol components containing small amounts of amide bonds, urethane bonds, ether bonds, and carbonate bonds. As for the production method of polyethylene terephthalate, any production method can be applied, such as the so-called direct polymerization method in which terephthalic acid and ethylene glycol, and optionally other dicarboxylic acids and / or other diols, are reacted directly, or the so-called transesterification method in which dimethyl ester of terephthalic acid and ethylene glycol, and optionally dimethyl ester of other dicarboxylic acids and / or other diols are transesterified.

[0034] The first phase difference layer may also preferably contain polycarbonate resin as its main component. In other words, in the first phase difference layer, it is preferable that the polycarbonate resin content is 50% by mass or more relative to the total mass of the first phase difference layer.

[0035] As the polycarbonate resin, known resins can be used. For example, polycarbonate resins having a bisphenol A skeleton can be mentioned, which are obtained by reacting a dihydroxy component and a carbonate precursor by an interfacial polymerization method or a melt polymerization method. For example, those described in JP-A-2006-277914, JP-A-2006-106386, and JP-A-2006-284703 can be preferably used. As commercially available products, "Tufron MD1500" (manufactured by Idemitsu Kosan Co., Ltd.) etc. can be used. Two or more of them may be used as necessary.

[0036] It is preferable that the first retardation layer contains an ultraviolet absorber in order to prevent deterioration of liquid crystal etc. of the liquid crystal display device by ultraviolet rays. The ultraviolet absorber is a compound having ultraviolet absorption ability and is not particularly limited as long as it can withstand the heat added in the manufacturing process of the first retardation layer.

[0037] As the ultraviolet absorber, there are organic ultraviolet absorbers and inorganic ultraviolet absorbers. From the viewpoint of transparency, organic ultraviolet absorbers are preferable. As the organic ultraviolet absorber, for example, benzotriazole-based, hydroxyphenyltriazine-based, and benzoxazine-based ultraviolet absorbers can be preferably used. As the ultraviolet absorber, for example, 2,2'-(p-phenylene)di-3,1-benzoxazin-4-one (manufactured by Fuji Film Fine Chemicals Co., Ltd., product name UVSORB 101) can be preferably used. Also, in order to widen the absorption width of ultraviolet rays, two or more ultraviolet absorbers having different maximum absorption wavelengths may be used in combination. The addition amount of the ultraviolet absorber is preferably 0.01 to 2% by mass, more preferably 0.01 to 1.5% by mass, based on the total mass of the resin contained in the first retardation layer.

[0038] Further, when the first retardation layer is a film having a multilayer structure, a structure having at least three layers is preferable, and the ultraviolet absorber is preferably blended in the intermediate layer. By blending the ultraviolet absorber in the intermediate layer, it is possible to prevent the ultraviolet absorber from bleeding out to the film surface, and as a result, properties such as the adhesiveness of the film can be maintained.

[0039] <Method for Manufacturing the First Retardation Layer>The method for manufacturing the first retardation layer is not particularly limited, but in order to impart the above characteristics, it is preferably manufactured by the following method. First, a resin (for example, a polyester resin) used for the first retardation layer is melt-extruded into a film shape, cooled and solidified by a casting drum to form an unstretched film, and then, if necessary, a coating liquid for forming an easy-adhesion layer is applied. It is preferable to stretch this unstretched film in the width direction 3 to 10 times, preferably 3 to 7 times, at a temperature of Tg to (Tg + 60)°C of the polyester film. The first retardation layer is preferably a polyester film stretched at least uniaxially, and a polyester film stretched at least uniaxially in the width direction is more preferable from the viewpoint of greatly expressing the in-plane retardation Re. Here, the glass transition temperature of the film is denoted as Tg.

[0040] Next, it is preferable to perform a heat treatment (referred to as heat setting here) on the obtained film at 140°C or higher and 220°C or lower for 1 to 60 seconds. The temperature of the heat setting is more preferably 150°C or higher and 220°C or lower, and still more preferably 150°C or higher and less than 220°C.

[0041] Furthermore, it is preferable to perform a reheat treatment (referred to as relaxation treatment here) on the obtained film while shrinking it by 0 to 20% in the longitudinal direction or / and the width direction at a temperature 10 to 20°C lower than the heat setting temperature. In this method, since the film is less likely to come into contact with the roll, it is less likely to form minute scratches or the like on the film surface, which is advantageous for application to optical uses. When the heat setting temperature is 150°C or higher and less than 220°C, the deviation of the orientation direction of the resin used for the first retardation layer becomes small, and the thermal dimensional change also becomes small, which is preferable.

[0042] [Second Retardation Layer] The above-described first embodiment and the above-described second embodiment include a second retardation layer. Hereinafter, the second retardation layer will be described.

[0043] One preferred aspect of the second phase difference layer is a patterned phase difference layer in which the slow axis orientation has an in-plane distribution. Here, "having an in-plane distribution of slow axis orientation" means that, as shown in Figure 2, the slow axis indicated by the arrow at a certain point 21 (region 1) on the second phase difference layer 12 and the slow axis indicated by the arrow at another point 22 (region 2) have different orientations. The pattern of the distribution of the slow axis orientation can be random, stripe, continuous change, or checkerboard, but the stripe shape is particularly preferred because it has a high effect in eliminating color unevenness. The stripe shape is also preferred because it generates less light diffraction and the transmitted image is less likely to be blurred. In other words, the second phase difference layer preferably has a region 1 and a region 2 in which the slow axis orientations are different from each other, and the region 1 and region 2 are arranged alternately in a stripe pattern. More specifically, in the stripe pattern, it is preferable that the region 1 and region 2, which extend in a single direction and have different slow axis orientations from each other, are arranged alternately in a direction perpendicular to the aforementioned single direction. Furthermore, it is preferable that the area of ​​region 1 and the area of ​​region 2 are close, and the area ratio of the area of ​​region 1 to the area of ​​region 2 is preferably 2.0 times or less, more preferably 1.5 times or less, even more preferably 1.1 times or less, and most preferably 1.0 times. Here, the area ratio represents the value obtained by dividing the area of ​​the larger of the two regions (area of ​​region 1 and area 2) by the area of ​​the smaller of the two regions (area of ​​the larger region / area of ​​the smaller region). Note that if the area of ​​region 1 and the area of ​​region 2 are equal, the above area ratio is 1.0. Note that if region 1 and region 2 are arranged in a stripe pattern, the width ratio of the width of region 1 to the width of region 2 is preferably 2.0 times or less, more preferably 1.5 times or less, even more preferably 1.1 times or less, and most preferably 1.0 times. Here, the width ratio represents the value obtained by dividing the width of the larger of the two regions (width of region 1 and width of region 2) by the width of the smaller of the two regions (width of the larger region / width of the smaller region). Furthermore, if the width of region 1 and the width of region 2 are equal, the above width ratio becomes 1.0.

[0044] The preferred range for the size of the pattern (region) of the slow axis distribution in the second phase difference layer can be estimated from the following viewpoints: (1) Reduction of image blur; the degree of image blur can be determined from the scattering angle θ (∝ 1 / domain size). It is preferable that the angle of light diffusion is smaller than the resolution of the eye, as this reduces image blur. From the viewpoint of reducing image blur, the preferred range for the period of the pattern can be expressed by equation as follows: Period of pattern [μm] > 100 μm. (2) Sufficiently smaller than the pupil size; when the depolarization element is placed near the eye, it is preferable that the period is smaller than the pupil size (approximately 2000 μm in diameter in a bright environment) as this allows for the elimination of color unevenness using the distribution of the slow axis orientation. From the viewpoint of pupil size, the preferred range for the period of the pattern can be expressed by equation as follows: Period of pattern [μm] < 2000 μm. In other words, it is preferable that the period of the pattern be greater than 100 μm and less than 2000 μm. In particular, from the standpoint of preventing blurring of the transmitted image, the period of the pattern is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1250 μm or more. The upper limit is preferably 1750 μm or less. As described above, when the second phase difference layer has regions 1 and 2 with different slow axis orientations, and regions 1 and 2 are arranged alternately in a stripe pattern, the width of regions 1 and 2 (stripe width) is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1250 μm or more. The upper limit is preferably less than 2000 μm, and even more preferably 1750 μm or less.

[0045] In the first embodiment of the second phase difference layer (the second phase difference layer in the first embodiment), the phase difference at a wavelength of 550 nm is preferably λ / 4. Here, the phase difference is not limited to the value of λ / 4, but can be tolerated within a certain range, preferably within ±30% of λ / 4, more preferably within ±20% of λ / 4, and most preferably within ±15% of λ / 4. In other words, the phase difference at a wavelength of 550 nm is preferably 96 to 178 nm, more preferably 110 to 165 nm, and even more preferably 117 to 158 nm.

[0046] In one embodiment of the second phase difference layer, a manufacturing method for imparting an in-plane distribution to the slow axis orientation includes irradiating a photo-alignment film that responds to the polarization direction of polarized exposure with light of different polarization directions within the plane. Specifically, two different polarizations may be irradiated through a light-shielding mask having a pattern. Alternatively, a linear polarization distribution may be imparted by interfering laser light of right-circular polarization and left-circular polarization. Furthermore, an axis distribution may be drawn by irradiating different polarizations in each region using a polarization light source with a small exposure spot, such as a laser.

[0047] The second aspect of the second phase difference layer (the second phase difference layer in the second embodiment) is preferably a patterned phase difference layer having an in-plane distribution of phase differences. Here, "having an in-plane distribution of phase differences" means that, as shown in Figure 3, the phase difference Re1 at a certain point 31 (region 1) on the second phase difference layer 12 and the phase difference Re2 at another point 32 (region 2) have different values. The pattern of the phase difference distribution can be random, stripe, continuous change, checkerboard, etc., but a stripe shape is particularly preferred because it has a high effect in eliminating color unevenness. Furthermore, a stripe shape is preferred because it generates less light diffraction and the transmitted image is less likely to be blurred. In other words, the second phase difference layer preferably has regions 1 and 2 with different phase differences from each other, and regions 1 and 2 are arranged alternately in a stripe pattern. More specifically, in the stripe pattern, it is preferable that regions 1 and 2, which extend in one direction and have different phase differences from each other, are arranged alternately in a direction perpendicular to the aforementioned one direction.

[0048] The preferred range for the size of the phase difference distribution pattern in the second phase difference layer can be estimated from the following viewpoints: (1) Reduction of image blur; the degree of image blur can be determined from the scattering angle θ (∝ 1 / domain size). It is preferable that the angle of light diffusion be smaller than the resolution of the eye, as this reduces image blur. From the viewpoint of reducing image blur, the preferred range for the period of the pattern can be expressed by equation as follows: Pattern period [μm] > 100 μm. (2) Sufficiently smaller than the pupil size; when the depolarization element is placed near the eye, it is preferable that the period be smaller than the pupil size (approximately 2000 μm in diameter in a bright environment) as this allows for the elimination of color unevenness using the phase difference distribution. From the viewpoint of pupil size, the preferred range for the period of the pattern can be expressed by equation as follows: Pattern period [μm] < 2000 μm. In other words, it is preferable that the period of the pattern be greater than 100 μm and less than 2000 μm. In particular, from the standpoint of preventing blurring of the transmitted image, the pattern period is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1250 μm or more. The upper limit is preferably 1750 μm or less. As described above, when the second phase difference layer has regions 1 and 2 with different phase differences from each other, and regions 1 and 2 are arranged alternately in a stripe pattern, the width of regions 1 and 2 (stripe width) is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1250 μm or more. The upper limit is preferably less than 2000 μm, and even more preferably 1750 μm or less.

[0049] As the second phase difference layer, a phase difference layer having a stripe shape with alternating regions 1 and 2 having different phase differences is preferred. In the second embodiment of the second phase difference layer, it is preferable that the phase difference of one region 1 at a wavelength of 550 nm is λ / 2, and the phase difference of the other region 2 at a wavelength of 550 nm is 0. In other words, it is preferable that the difference in phase differences between region 1 and region 2 at a wavelength of 550 nm is λ / 2. Here, the phase difference of region 1 at a wavelength of 550 nm is not limited to the value of λ / 2, but can be within a certain range, preferably within ±30% of λ / 2, more preferably within ±20% of λ / 2, and most preferably within ±15% of λ / 2. In other words, the phase difference at a wavelength of 550 nm is preferably 192 to 357 nm, more preferably 220 to 330 nm, and even more preferably 233 to 316 nm. The phase difference in region 2 at a wavelength of 550 nm is preferably within ±80 nm, more preferably within ±50 nm, and even more preferably within ±30 nm. In the second embodiment of the second phase difference layer, the manufacturing method for imparting an in-plane distribution to the phase difference may be, for example, to solidify a portion first by mask exposure, and then to create an isotropic layer in the remaining region by exceeding the iso point. Alternatively, regions with and without the phase difference layer made of liquid crystal material may be painted separately using inkjet or the like.

[0050] <Material for the Second Phase Difference Layer> There are no restrictions on the material used to form the second phase difference layer; various known materials used for forming phase difference layers can be used. Examples include birefringent particles, birefringent polymers, and liquid crystal compounds. Among these, liquid crystal compounds that can form a second phase difference layer with uniform thickness and a high aspect ratio (in-plane length / thickness), and that also have high optical anisotropy, are preferred. Liquid crystal compounds having polymerizable groups are particularly suitable. By using liquid crystal compounds to form the second phase difference layer, in addition to excellent phase difference characteristics, processability and durability can also be improved.

[0051] Liquid crystal compounds can be easily immobilized by heating and UV irradiation, and maintain stable optical properties over long periods. Moreover, liquid crystal compounds allow for precise adjustment of desired phase difference characteristics, and because they exhibit a liquid crystal phase within a specific temperature range, their phase difference characteristics can be optimized through temperature control during the manufacturing process.

[0052] There are no restrictions on the birefringence wavelength dispersion characteristics of liquid crystal compounds, but inverse wavelength dispersion is preferred. Inverse wavelength dispersion represents Re(450) / Re(550) < 1.00 and Re(650) / Re(550) ≥ 1.00. This allows for a larger phase change with respect to wavelength changes. Here, phase is an index representing the state of the light wave and is a value obtained by Re(λ) / λ × 2π. Therefore, by fabricating the second phase difference layer using a liquid crystal compound with forward wavelength dispersion, color changes when observing an image display device that emits polarized light with a polarizing element attached can be suppressed.

[0053] Furthermore, when selecting liquid crystal compounds, it is preferable to pay attention to physical properties such as heat resistance, light resistance, and moisture resistance, and to select materials with durability appropriate to the usage environment. This makes it possible to ensure long-term reliability in wearable devices such as AR glasses and other optical devices.

[0054] <Method for Manufacturing the Second Phase Difference Layer> There are no limitations on the method for manufacturing the second phase difference layer, and known methods can be used depending on the material used to form the second phase difference layer. As an example, a method is exemplified in which a liquid crystalline material having crosslinkable groups is uniformly coated onto a support, then heat-treated at a specific temperature, and cured by ultraviolet irradiation or the like to produce the second phase difference layer. In other words, a liquid crystalline material having crosslinkable groups is a liquid crystal composition containing a liquid crystal compound having crosslinkable groups.

[0055] A common method for manufacturing a second phase difference layer using liquid crystal compounds involves using a substrate layer (alignment film) that has liquid crystal alignment restricting force and a uniform orientation restricting direction, and then applying and curing a liquid crystal composition onto this substrate layer to form a phase difference layer. Methods for making the orientation restricting direction uniform in the plane include rubbing the substrate layer and uniform linearly polarized light irradiation of the photo-alignment film.

[0056] Furthermore, in order to create a phase difference in the second phase difference layer, it is preferable to orient the rod-shaped liquid crystal compounds horizontally and the disc-shaped liquid crystal compounds vertically. To achieve this, it is preferable to control the surface energy of the underlying layer. Specifically, when creating the second phase difference layer containing rod-shaped liquid crystal compounds, it is preferable to make the underlying layer hydrophobic. On the other hand, when creating the second phase difference layer containing disc-shaped liquid crystal compounds, it is preferable to make the underlying layer hydrophilic.

[0057] The depolarizing element of the present invention may consist only of a phase difference layer, or it may have the support (substrate) and underlayer described above. As the support, various known materials can be used as long as they can support the first phase difference layer and the second phase difference layer and transmit the target light, such as visible light. For example, examples of materials for forming a transparent support include cellulose polymers (hereinafter referred to as cellulose acylate), such as triacetylcellulose, thermoplastic norbornene resins (such as Zeonex and Zeonor from Nippon Zeon Co., Ltd., and Arton from JSR Corporation), acrylic resins, and polyester resins, as well as glass. Furthermore, in addition to these layers, the depolarizing element of the present invention may have various layers (films) such as an anti-reflective layer, a phase difference layer, a polarizer layer, a color absorption layer, a transparent conductive layer, and an antistatic layer, as needed.

[0058] [Phase Difference Layer] The third embodiment described above includes a phase difference layer. The phase difference layer will be described below.

[0059] The phase difference layer is a patterned phase difference layer in which the phase difference has an in-plane distribution. Here, "the phase difference has an in-plane distribution" means that, as shown in Figure 4, the phase difference Re1 at a certain point 41 (region 1) on the phase difference layer 13 and the phase difference Re2 at another point 42 (region 2) have different values. The pattern of the phase difference can be selected from random, stripe, continuous change, and checkerboard, but the stripe shape is particularly preferred because it has a high effect in eliminating color unevenness. The stripe shape is also preferred because it generates less light diffraction and the transmitted image is less likely to be blurred. In other words, it is preferable that the phase difference layer has regions 1 and 2 with different phase differences from each other, and that regions 1 and 2 are arranged alternately in a stripe shape. More specifically, in the stripe shape, it is preferable that regions 1 and 2, which extend in one direction from each other and have different phase differences from each other, are arranged alternately in a direction perpendicular to the aforementioned one direction.

[0060] The preferred range for the size of the phase difference distribution pattern in the phase difference layer can be estimated from the following viewpoints: (1) Image blur reduction; the degree of image blur can be determined from the scattering angle θ (∝ 1 / domain size). It is preferable that the angle of light diffusion is smaller than the resolution of the eye, as this reduces image blur. From the viewpoint of image blur reduction, the preferred range for the pattern period can be expressed by equation as follows: Pattern period [μm] > 100 μm. (2) Sufficiently smaller than pupil size; when the depolarization element is placed near the eye, it is preferable that the period is smaller than the pupil size (approximately 2000 μm in diameter in a bright environment) as this allows for the elimination of color unevenness using the phase difference distribution. From the viewpoint of pupil size, the preferred range for the pattern period can be expressed by equation as follows: Pattern period [μm] < 2000 μm. In other words, it is preferable that the pattern period be greater than 100 μm and less than 2000 μm. In particular, from the standpoint of preventing blurring of the transmitted image, the pattern period is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1250 μm or more. The upper limit is preferably 1750 μm or less. As described above, when the second phase difference layer has regions 1 and 2 with different phase differences from each other, and regions 1 and 2 are arranged alternately in a stripe pattern, the width of regions 1 and 2 (stripe width) is preferably 500 μm or more, more preferably 1000 μm or more, and even more preferably 1250 μm or more. The upper limit is preferably less than 2000 μm, and even more preferably 1750 μm or less.

[0061] <Phase difference of the phase difference layer> The in-plane retardation in the normal direction of the phase difference layer at a wavelength of 550 nm is from 3,000 nm to 100,000 nm, preferably from 5,000 nm to 50,000 nm, and more preferably from 7,000 nm to 20,000 nm. If the in-plane retardation of the phase difference layer at a wavelength of 550 nm is 3,000 nm or more, the polarization depolarization ability due to wavelength scrambling is increased, which can suppress color unevenness and blackout. On the other hand, if the in-plane retardation of the phase difference layer at a wavelength of 550 nm is 100,000 nm or less, it can suppress the decrease in transmittance and deterioration of transmitted image clarity due to the phase difference layer being too thick.

[0062] As the phase difference layer, a phase difference layer having a stripe shape with alternating regions 1 and 2 having different phase differences is preferred. In the phase difference layer, the difference between the phase difference of one region 1 and the phase difference of another region 2 is preferably λ / 2. Here, the difference in phase difference is not limited to the value of λ / 2, but can be within a certain range, preferably within ±30% of λ / 2, more preferably within ±20% of λ / 2, and even more preferably within ±15% of λ / 2. In other words, the phase difference at a wavelength of 550 nm is preferably 192 to 357 nm, more preferably 220 to 330 nm, and even more preferably 233 to 316 nm.

[0063] <Method for imparting an in-plane distribution of phase difference to a phase difference layer> As a method for imparting an in-plane distribution of phase difference to a phase difference layer, the film thickness in a part of the phase difference layer may be reduced by plasma etching or the like. Alternatively, a film thickness distribution may be imparted by pressing at high temperature and high pressure or the like.

[0064] <Method of manufacturing the phase difference layer> The composition and manufacturing method of the phase difference layer are the same as those of the first phase difference layer described above.

[0065] <Near-Eye Display> The near-eye display of the present invention has the polarization depolarization element of the present invention. As a near-eye display, various known near-eye displays other than those having the polarization depolarization element of the present invention can be used. Specific examples of near-eye displays include AR glasses, VR (Virtual reality) glasses, and MR (Mixed reality) glasses. A preferred near-eye display is one that includes the polarization depolarization element of the present invention and a polarizer, wherein the polarizer is positioned on the user's side when the user wears the near-eye display.

[0066] The present invention will be specifically described below based on examples. The materials, reagents, amounts and proportions of substances, and procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the present invention is not limited to the following examples.

[0067] [Preparation of the first phase difference layer] <First phase difference layer used in comparative examples and examples> A polyethylene terephthalate (PET) film with a thickness of 100 μm was prepared by the following method.

[0068] —Synthesis of raw material polyester— —Raw material polyester 1— As shown below, raw material polyester 1 (Sb catalyst-based PET) was obtained by a continuous polymerization apparatus using a direct esterification method in which terephthalic acid and ethylene glycol were directly reacted to remove water by distillation, followed by polycondensation under reduced pressure.

[0069] (1) Esterification reaction: In the first esterification reactor, 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol were mixed over 90 minutes to form a slurry, which was continuously supplied to the first esterification reactor at a flow rate of 3800 kg / h. Furthermore, an ethylene glycol solution of antimony trioxide was continuously supplied, and the reaction was carried out at a reactor temperature of 250°C, under stirring, with an average residence time of approximately 4.3 hours. At this time, antimony trioxide was continuously added so that the amount of Sb added was 150 ppm by mass in terms of elemental value.

[0070] The reactants were transferred to a second esterification reactor and reacted under stirring at a reactor temperature of 250°C for an average residence time of 1.2 hours. Ethylene glycol solutions of magnesium acetate and ethylene glycol solutions of trimethyl phosphate were continuously supplied to the second esterification reactor so that the amounts of Mg and P added were 65 ppm by mass and 35 ppm by mass, respectively, on an elemental basis.

[0071] (2) Polycondensation reaction The esterification reaction product obtained above is continuously supplied to the first polycondensation reaction vessel and stirred, at a reaction temperature of 270°C and a reaction vessel pressure of 20 torr (2.67 × 10⁻¹⁰). －３ Polycondensation was performed at MPa with an average residence time of approximately 1.8 hours.

[0072] Furthermore, the mixture is transferred to a second condensation reactor, where it is stirred, with a reactor temperature of 276°C and a reactor pressure of 5 torr (6.67 × 10⁻¹⁰). －４ The reaction (polycondensation) was carried out under conditions of MPa with a residence time of approximately 1.2 hours.

[0073] Next, the mixture is transferred to a third condensation reactor, where the reactor temperature is 278°C and the reactor pressure is 1.5 torr (2.0 × 10⁻⁶). －４ The reaction (polycondensation) was carried out under conditions of MPa with a residence time of 1.5 hours to obtain the reactant (polyethylene terephthalate (PET)).

[0074] Next, the resulting reaction product was extruded in strand form into cold water and immediately cut to produce polyester pellets (cross-section: major diameter approximately 4 mm, minor diameter approximately 2 mm, length: approximately 3 mm). The resulting polymer had an intrinsic viscosity IV = 0.63. This polymer was designated as raw material polyester 1.

[0075] The intrinsic viscosity IV was determined by dissolving the raw material polyester 1 in a 1,1,2,2-tetrachloroethane / phenol (= 2 / 3 [mass ratio]) mixed solvent and measuring the viscosity of the solution in this mixed solvent at 25°C.

[0076] --Raw material polyester 2-- 10 parts by mass of dried ultraviolet absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazinon-4-one)) and 90 parts by mass of raw material polyester 1 (IV = 0.63) were mixed, and raw material polyester 2 containing the ultraviolet absorber was obtained using a kneading extruder.

[0077] ―Film Forming Process― Raw material polyester 1 (90 parts by mass) and raw material polyester 2 (10 parts by mass) containing an ultraviolet absorber were dried to a moisture content of 20 ppm by mass or less, and then placed into the hopper 1 of a 50 mm diameter single-screw kneading extruder 1, and melted at 300°C in the extruder 1. The molten resin was extruded from the die through a gear pump and filter (pore size 20 μm) under the following extrusion conditions. The extrusion conditions for the molten resin were set to a pressure fluctuation of 1% and a temperature distribution of the molten resin of 2%, and the molten resin was extruded from the die. Specifically, the back pressure was increased by 1% relative to the average pressure inside the extruder barrel, and the extruder piping temperature was heated to a temperature 2% higher than the average temperature inside the extruder barrel. The molten resin extruded from the die was extruded onto a cooling cast drum set to a temperature of 25°C, and adhered to the cooling cast drum using an electrostatic application method. The film was peeled off using a peeling roll positioned opposite the cooling cast drum to obtain an unstretched polyester film 1.

[0078] —Transverse stretching process— —Preheating section— The preheating temperature was set to 90°C, and the unstretched polyester film 1 was heated to a temperature at which it could be stretched.

[0079] --Stretching Section-- A preheated, unstretched polyester film 1 was guided into a tenter (transverse stretcher), and while holding the ends of the film with clips, it was transversely stretched in the TD direction (film width direction, transverse direction) under the following conditions and by the following method and conditions to obtain a transversely stretched polyester film 1. <Conditions> ・Transverse stretching temperature: 90°C ・Transverse stretching ratio: 4.3 times

[0080] --Thermal Fixation Section-- Next, a thermal fixation process was performed while controlling the surface temperature of the transversely stretched polyester film 1 to the following temperature: <Conditions> ・Thermal fixation temperature: 180°C ・Thermal fixation time: 15 seconds

[0081] --Thermal Relaxation Section-- The heat-set transversely stretched polyester film 1 was heated to the following temperature to relax the film. • Thermal relaxation temperature: 170°C • Thermal relaxation rate: 2% in the TD direction (film width direction, transverse direction)

[0082] --Cooling Section-- Next, the transversely stretched polyester film 1, after heat relaxation, was cooled at a cooling temperature of 50°C.

[0083] The in-plane retardation of the transversely stretched polyester film 1 obtained in this manner after thermal relaxation was measured using Axoscan, and the in-plane retardation Re(550) = 10000 nm at a wavelength of 550 nm of the first phase difference layer was found to be 10000 nm.

[0084] [Fabrication of the first phase difference layer 2] The first phase difference layer 2 was fabricated using the same method as the first phase difference layer, except that the film thickness conditions were changed so that the in-plane retardation Re(550) = 2500 nm at a wavelength of 550 nm.

[0085] [Production of the Second Retardation Layer] <Second Retardation Layer 1> The patterned retardation layer, which is the second retardation layer, was produced by the following method. As a support, a PET film with a thickness of 100 μm (manufactured by Toyobo Co., Ltd., Cosmo Shine A4265) was prepared. This PET film has an easy adhesion layer on one side. On this support, the coating liquid PA-1 for forming an alignment film shown below was applied with a wire bar and then dried with warm air at 120°C for 60 seconds. Then, in a low-oxygen atmosphere (100 ppm or less), at 70°C, with an illuminance of 100 mW / cm ２ , the film was cured by irradiating linearly polarized ultraviolet light with an irradiation dose of 100 mJ / cm ２ . This ultraviolet light was obtained by passing through a long-pass filter having a transmission band at a wavelength of 340 nm or more. Next, the cured coating film was irradiated with linearly polarized ultraviolet light (wavelength 313 nm) with an illuminance of 7 mW / cm ２ and an irradiation dose of 7.9 mJ / cm ２ from the alignment film side to form a provisional photo-alignment film. The linearly polarized ultraviolet light with a wavelength of 313 nm was obtained by passing the ultraviolet light emitted from a mercury lamp through a band-pass filter having a transmission band at a wavelength of 313 nm and a wire grid polarizer. Next, a stripe-shaped mask with a period of 1.5 mm was prepared, and after overlapping the mask on the provisional photo-alignment film, linearly polarized ultraviolet light (wavelength 313 nm) with an illuminance of 7 mW / cm ２ and an irradiation dose of 7.9 mJ / cm ２ was irradiated from the alignment film side to perform the second polarization exposure. Here, the polarization direction of the second polarization exposure was exposed so as to be orthogonal to the polarization direction of the first polarization exposure. Also, the stripe-shaped mask used was one in which the transmittance to ultraviolet light was less than 1% in region 1, 80% or more in region 2, and regions 1 and 2 were arranged alternately with the same width in a stripe shape. Thereby, a photo-alignment film E1 with an alignment direction changing by 90° at a period of 1.5 mm was obtained. At this time, both the width of region 1 and the width of region 2 were 0.75 mm.

[0086] (Coating Liquid PA-1 for Forming Alignment Film) The composition shown below was stirred and dissolved at room temperature in a container to prepare the coating liquid PA-1 for forming an alignment film.

[0087] ------------------------------------------------------------------- (Coating solution PA-1 for forming orientation film) ------------------------------------------------------------------- ・100.00 parts by mass of the polymer M-PA-1 below ・5.00 parts by mass of the photopolymerization initiator A below ・2625.00 parts by mass of n-butyl acetate -------------------------------------------------------------------

[0088] Polymer M-PA-1

[0089]

[0090] Photopolymerization initiator A

[0091]

[0092] Composition F1, having the composition described below, was applied to the photo-alignment film E1 using a bar coater. The coating formed on the photo-alignment film E1 was heated to 120°C with hot air, then cooled to 60°C, and then heated at a wavelength of 365 nm and a pressure of 100 mJ / cm² using a high-pressure mercury lamp under a nitrogen atmosphere. ２ The coating is irradiated with ultraviolet light, followed by heating to 120°C while applying 500 mJ / cm² of UV light. ２ By irradiating the coating with ultraviolet light, the orientation of the liquid crystalline compound was fixed, and a phase difference film 1 having a second phase difference layer 1 was fabricated. The thickness of the second phase difference layer 1 was 2.7 μm, and the Re(550) was 155 nm. The second phase difference layer 1 was a patterned phase difference layer having regions 1 and 2 with different slow axis orientations. Regions 1 and 2 were arranged alternately in a stripe pattern.

[0093] ------------------------------------------------------------------- Composition F1 ------------------------------------------------------------------- ・43.50 parts by mass of the polymerizable liquid crystalline compound LA-1 below ・43.50 parts by mass of the polymerizable liquid crystalline compound LA-2 below ・8.00 parts by mass of the polymerizable liquid crystalline compound LA-3 below ・5.00 parts by mass of the polymerizable liquid crystalline compound LA-4 below ・0.55 parts by mass of the polymerization initiator PI-1 below ・0.20 parts by mass of the leveling agent T-1 below ・235.00 parts by mass of cyclopentanone -------------------------------------------------------------------

[0094] Polymerizable liquid crystalline compound LA-1 (tBu represents a tert-butyl group)

[0095]

[0096] Polymerizable liquid crystal compound LA-2

[0097]

[0098] Polymerizable liquid crystal compound LA-3

[0099]

[0100] Polymerizable liquid crystalline compound LA-4 (Me represents a methyl group)

[0101]

[0102] Polymerization initiator PI-1

[0103]

[0104] Leveling agent T-1

[0105]

[0106] <Second Phase Difference Layer 2> The second phase difference layer 2 was fabricated by the following method. A PET film with a thickness of 100 μm (Cosmoshine A4265, manufactured by Toyobo Co., Ltd.) was prepared as a support. This PET film has an easy-adhesion layer on one side. The orientation film forming coating liquid PA-1 was applied to the side of this support without the easy-adhesion layer using a wire bar, and then dried with hot air at 120°C for 60 seconds. After that, under a low-oxygen atmosphere (100 ppm or less), at 70°C and with an illuminance of 100 mW / cm² ２ , irradiation amount 100mJ / cm ２ The film was cured by irradiating it with linearly polarized ultraviolet light. This ultraviolet light was obtained by passing it through a long-pass filter with a transmission band of wavelength 340 nm or higher. Next, the cured coating was irradiated with an irradiance of 7 mW / cm². ２ , irradiation amount 7.9mJ / cm ２ A photo-aligned film was formed by irradiating it with linearly polarized ultraviolet light (wavelength 313 nm) from the alignment film side. Linearly polarized ultraviolet light with a wavelength of 313 nm was obtained by transmitting ultraviolet light emitted from a mercury lamp through a bandpass filter having a transmission band at 313 nm and a wire grid polarizer. This resulted in the acquisition of photo-aligned film E2.

[0107] Composition F1 was applied onto the photo-alignment film E2 using a bar coater. The coating formed on the photo-alignment film E2 was heated to 120°C with hot air, then cooled to 60°C, and then heated at a wavelength of 365 nm and a pressure of 100 mJ / cm² using a high-pressure mercury lamp under a nitrogen atmosphere. ２ The coating was irradiated with ultraviolet light. During this process, a striped mask with a period of 1.5 mm was placed over the liquid crystal coating. The striped mask used had a transmittance of less than 1% for region 1 and 80% or more for region 2, with regions 1 and 2 having the same width and arranged alternately in stripes. This created areas that were exposed to curing ultraviolet light and areas that were not, with a period of 1.5 mm. This resulted in the creation of a striped pattern of a first region where the liquid crystal orientation was fixed and a second region where the liquid crystal orientation was not fixed and remained fluid, with a period of 1.5 mm. Next, the striped mask was removed, and the coating was heated to 150°C to make the liquid crystal orientation in the second region isotropic. 500 mJ / cm² was then applied to the coating in this state. ２By irradiating with ultraviolet light, the liquid crystal in the second region was fixed in an isotropic state. This created a second phase difference layer 2 having a first region with a phase difference and a second region without a phase difference. The thickness of the coating film was 5.4 μm, and the in-plane retardation Re(550) of the first region at a wavelength of 550 nm was 310 nm. The second phase difference layer 2 was a patterned phase layer having regions 1 and 2 with different phase differences. Regions 1 and 2 were arranged alternately in a stripe pattern.

[0108] <Second Phase Difference Layers 3-5> The second phase difference layers 3-5 were fabricated using the same method as the second phase difference layer 1, except that the width of each region was changed to the widths shown in Tables 1 and 2.

[0109] [Fabrication of a Phase Difference Layer Having a Phase Difference Distribution] To fabricate a phase difference layer having a phase difference distribution, first, a first phase difference layer (polyester film, in-plane retardation of 10,000 nm) was prepared. Next, a striped mask with a period of 1.5 mm was laminated to the surface of the obtained polyester film. This mask has a laminated structure of PET and adhesive, with a first region containing PET and adhesive and a second region without PET and adhesive arranged in a striped pattern. The adhesive side was laminated to the first phase difference layer. By performing plasma etching through this mask, the polyester material in the areas where the polyester film without PET and adhesive is exposed can be removed, reducing the thickness and phase difference. Plasma treatment was performed using a high-frequency plasma device at a condition of 13.56 MHz to etch the mask, and the mask was peeled off to obtain a phase difference layer having a phase difference distribution. The plasma treatment was performed by introducing a gas with an oxygen:argon composition of 1:1 and applying a high frequency of 50 W at a pressure of 3.0 Pa for 300 seconds. The thickness of the first region of the resulting phase difference layer was 100 μm, and the thickness of the etched second region was 96.7 μm.

[0110] [Measurement] For each fabricated phase difference layer, in-plane retardation and slow axis orientation were measured. Here, the first phase difference layer and the phase difference layer were measured using the laminate obtained by bonding the first phase difference layer and the phase difference layer to glass. The second phase difference layers 1 to 5 were measured using the laminate obtained by transferring the second phase difference layers 1 to 5 to glass. As for the transfer method, the coated side was first bonded to the glass via an adhesive, and then the PET support was peeled off. This created a measurement sample consisting of glass / adhesive / phase difference layer.

[0111] Using a Nikon ECLIPSE LV100POL polarizing microscope, the phase difference and lagging axis distribution (in-plane distribution of axis angles) were measured using the rotational compensator method (reference: Spectroscopic Ellipsometry, by Hiroyuki Fujiwara). The phase difference was measured as the in-plane phase difference Re.

[0112] The measurement results for each phase difference layer are shown in Tables 1 and 2. The angle of the lagging axis orientation in the regions in Tables 1 and 2 represents the angle with the longitudinal direction of each phase difference layer.

[0113]

[0114]

[0115] [Fabrication of the depolarizing element of Example 1] The first phase difference layer was bonded to the glass via an adhesive, and then the second phase difference layer 1 was bonded via an adhesive. The PET support was then peeled off and removed to obtain the depolarizing element 1 of Example 1.

[0116] [Fabrication of Depolarization Elements for Examples 2-6 and Comparative Examples 1-3] Following the same procedure as in Example 1, the depolarization elements for Examples 2-6 and Comparative Examples 1-3 were fabricated using the configurations shown in Tables 3 and 4.

[0117] [Evaluation of Blackout and Color Unevenness] For each example and comparative example, a linear polarizing plate was placed in conjunction with the image, with the linear polarizing plate positioned towards the eye. A solid white image was displayed on an Apple iPad Pro (2021 model, 11-inch, LCD display) and observed. Blackout and color unevenness were visually evaluated according to the criteria described below. The results are shown in Tables 3 and 4. In Comparative Examples 1 to 3, it was confirmed that the image display device exhibited significant color unevenness. On the other hand, in Examples 1 to 6, it was confirmed that the color unevenness was within acceptable limits.

[0118] The evaluation was conducted according to the following criteria: (Blackout suppression) A: No blackout. B: Blackout occurs. (Color unevenness) A: No color unevenness. B: Slight color variation. C: Color variation exists but is within acceptable limits. D: Color unevenness is clearly visible.

[0119]

[0120]

[0121] [Evaluation of Blackout and Color Unevenness in Near-Eye Displays] Instead of a polarizing plate, XREAL Air2 Pro AR glasses manufactured by XREAL Corporation were used as polarizing elements. The depolarizing elements of each example and comparative example were bonded to these glasses to create near-eye displays with the depolarizing elements of the examples and comparative examples. It was confirmed that these AR glasses have the properties of a circular polarizer, cutting the left circularly polarized component of ambient light and transmitting the right circularly polarized component. A solid white image was displayed on an Apple iPad Pro (2021 model, 11-inch, using an LCD display) through this near-eye display and observed. It was confirmed that this image display device mainly emits left circularly polarized light. Therefore, when the iPad Pro was observed through an XREAL Air2 Pro without a depolarizing element, a blackout occurred. When this was observed with an XREAL Air2 Pro having the depolarizing elements of each example and comparative example, it was confirmed that the same results as in Table 2 were obtained for both blackout and color unevenness. Furthermore, when observed with the XREAL Air2 Pro equipped with the depolarizing element of Example 6, in which the width of each region is 0.04 mm (i.e., the period is smaller than 0.1 mm), the results for both blackout and color unevenness were similar to those in Table 4 and were good, but the outside world was visible as blurred.

[0122] 1 Polarization depolarization element 11 First phase difference layer 12 Second phase difference layer 13 Phase difference layer 21 Region with first axial orientation 22 Region with second axial orientation 31 Region with first phase difference 32 Region with second phase difference 41 Region with first phase difference 42 Region with second phase difference

Claims

1. A depolarization element comprising a first phase difference layer and a second phase difference layer, wherein the in-plane retardation of the first phase difference layer at a wavelength of 550 nm is from 3000 nm to 100000 nm, and the second phase difference layer is a patterned phase difference layer having a distribution of at least one of the slow phase axis orientation and phase difference in the plane.

2. The depolarization element according to claim 1, wherein the second phase difference layer is a patterned phase difference layer having a distribution of slow axis orientations in the plane.

3. The depolarization element according to claim 2, wherein the pattern phase difference layer has a region 1 and a region 2 whose slow axis orientations are different from each other, and the region 1 and the region 2 are arranged alternately in a stripe pattern.

4. The depolarization element according to claim 2, wherein the phase difference of the second phase difference layer at a wavelength of 550 nm is λ / 4.

5. The depolarization element according to claim 1, wherein the second phase difference layer is a patterned phase difference layer having a distribution of phase differences in its plane.

6. The depolarizing element according to claim 5, wherein the pattern phase difference layer has regions 1 and 2 having different phase differences from each other, and regions 1 and 2 are arranged alternately in a stripe pattern.

7. The depolarization element according to claim 6, wherein in the second phase difference layer, the difference between the phase difference of region 1 at a wavelength of 550 nm and the phase difference of region 2 at a wavelength of 550 nm is λ / 2.

8. A depolarizing element having a phase difference layer, wherein the in-plane retardation of the phase difference layer at a wavelength of 550 nm is from 3,000 nm to 100,000 nm, and the phase difference layer is a patterned phase difference layer having a phase difference distribution in the plane.

9. The depolarizing element according to claim 8, wherein the pattern phase difference layer has regions 1 and 2 having different phase differences from each other, and regions 1 and 2 are arranged alternately in a stripe pattern.

10. The depolarization element according to claim 9, wherein in the phase difference layer, the difference between the phase difference of region 1 at a wavelength of 550 nm and the phase difference of region 2 at a wavelength of 550 nm is λ / 2.

11. A near-eye display having a polarization-depolarizing element according to any one of claims 1 to 10.

12. A near-eye display comprising a polarization-depolarizing element according to any one of claims 1 to 10 and a polarizer, wherein the polarizer is positioned on the user's side when the user wears the near-eye display.

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