Viewing angle control system and image display device

Abstract

The present invention addresses the problem of providing a viewing angle control system capable of switching between a light-blocking mode and a transmission mode when viewed from an oblique direction at a predetermined azimuth angle, wherein an image is more difficult to view in the light-blocking mode and easier to view in the transmission mode.　A viewing angle control system (10a) according to the present invention has a light absorption anisotropic layer (12), a liquid crystal cell (14), and a polarizer (16) in this order. The angle formed by the transmittance central axis of the light absorption anisotropic layer (12) and the normal of the light absorption anisotropic layer (12) is 0-45°. The viewing angle control system has an optical compensation layer (18) between the light absorption anisotropic layer (12) and the liquid crystal cell (14) and / or between the liquid crystal cell (14) and the polarizer (16), and does not include another light absorption anisotropic layer or another polarizer between the light absorption anisotropic layer (12) and the polarizer (16).

Description

Viewing angle control system, image display device

[0001] The present invention relates to a viewing angle control system, and also to an image display device including the viewing angle control system.

[0002] In recent years, display devices such as liquid crystal display devices have been widely used as displays for personal computers, smartphones, and the like. Displays are also often adopted in mobile devices. Devices with such displays are often used in public places, and therefore there is a demand for technology to prevent others from peeking at them.

[0003] Furthermore, in recent years, liquid crystal display devices have come to be used as in-vehicle displays inside automobiles. As in-vehicle displays have become larger, images displayed on the displays may be reflected on the windshield or other surfaces, obstructing the driver's field of vision, and therefore there is a demand for technology to prevent such reflections.

[0004] Furthermore, it is also preferable that the width of the viewing angle of such a display can be switched as needed. For example, Patent Document 1 discloses a viewing angle control system that is capable of switching the width of the viewing angle and includes a substrate in which dyes are vertically aligned and a switching cell.

[0005] US Patent Application Publication No. 2021 / 0349335

[0006] The viewing angle control system is required to be applied to an image display device and be able to switch between a transmissive mode in which an image is visible and a shading mode in which the image is difficult to view when observed from an oblique direction at a specific azimuth angle. Recently, there has been a demand for an image to be more easily visible in the transmissive mode and more difficult to view in the shading mode. The inventors have studied the transmissive mode and the shading mode and found that the technology described in Patent Document 1 does not meet the standards currently required and that further improvement is necessary.

[0007] Therefore, an object of the present invention is to provide a viewing angle control system that can be applied to an image display device and can switch between a light-shielding mode and a light-transmitting mode when viewed from an oblique direction at a predetermined azimuth angle, making the image less visible in the light-shielding mode and more visible in the light-transmitting mode. Another object of the present invention is to provide an image display device using the viewing angle control system.

[0008] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, they have found that the above problems can be solved by the following configuration.

[0009] [1] A viewing angle control system comprising, in this order, an optically absorptive anisotropic layer, a liquid crystal cell, and a polarizer, wherein the angle between the transmittance central axis of the optically absorptive anisotropic layer and a normal to the optically absorptive anisotropic layer is 0 to 45°, and an optical compensation layer is provided between the optically absorptive anisotropic layer and the liquid crystal cell and / or between the liquid crystal cell and the polarizer, and wherein no other optically absorptive anisotropic layer or other polarizer is provided between the optically absorptive anisotropic layer and the polarizer. [2] The viewing angle control system according to [1], wherein the liquid crystal cell is an in-plane switching liquid crystal cell. [3] The viewing angle control system according to [1], wherein the liquid crystal cell is a vertical alignment liquid crystal cell or an electric field controlled birefringence liquid crystal cell. [3] The viewing angle control system according to any one of [1] to [3], wherein the optical compensation layer is disposed between the optically absorptive anisotropic layer and the liquid crystal cell. [5] An image display device including the viewing angle control system according to any one of [1] to [4].

[0010] According to the present invention, a viewing angle control system can be provided that is applied to an image display device and can switch between a light-shielding mode and a light-transmitting mode when viewed from an oblique direction at a predetermined azimuth angle, making it harder to see an image in the light-shielding mode and easier to see an image in the light-transmitting mode.Furthermore, according to the present invention, an image display device using the viewing angle control system can also be provided.

[0011] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

[0012] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0013] The meaning of each description in this specification is as follows: In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0014] In this specification, "parallel" and "orthogonal" do not mean "parallel" or "orthogonal" in the strict sense, but mean a range of ±5° from parallel or orthogonal. Furthermore, in this specification, unless otherwise specified, "polar angle" means the angle with respect to the normal direction of the film.

[0015] In this specification, the liquid crystal composition and liquid crystalline compound conceptually include those that no longer exhibit liquid crystallinity due to curing or the like.

[0016] In addition, in this specification, each component may use a single substance corresponding to the component, or two or more substances may be used in combination. Here, when two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified. In addition, in this specification, "(meth)acrylate" is a notation representing "acrylate" or "methacrylate", "(meth)acrylic" is a notation representing "acrylic" or "methacrylic", and "(meth)acryloyl" is a notation representing "acryloyl" or "methacryloyl".

[0017] In the present invention, the refractive indices nx and ny are the refractive indices in the in-plane direction of the optical member, and typically, nx is the refractive index in the slow axis direction, and ny is the refractive index in the fast axis direction (i.e., the direction perpendicular to the slow axis). Also, nz is the refractive index in the thickness direction. nx, ny, and nz can be measured, for example, using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) with a sodium lamp (λ = 589 nm) as a light source. Furthermore, when measuring wavelength dependency, measurements can be performed using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. Values ​​in the Polymer Handbook (John Wiley & Sons, Inc.) and catalogs for various optical films can also be used.

[0018] In this specification, Re(λ) and Rth(λ) respectively represent the in-plane retardation and thickness direction retardation at wavelength λ, and are expressed by the following formulas (1) and (2) using refractive indices nx, ny, and nz and film thickness d (μm). Formula (1): Re(λ)=(nx-ny)×d×1000(nm) Formula (2): Rth(λ)=((nx+ny) / 2-nz)×d×1000(nm) Unless otherwise specified, the wavelength λ is 550 nm. The slow axis orientation, Re(λ), and Rth(λ) can be measured using, for example, an AxoScan OPMF-1 (manufactured by OptoScience). Note that when simply referring to Re and Rth, the values ​​at λ=550 nm are indicated.

[0019] In this specification, Δnd refers to the retardation caused by a layer in which rod-shaped or discotic liquid crystal compounds are twisted and aligned along the thickness direction, and is expressed as the product of the thickness d of the liquid crystal layer and the birefringence Δn of the liquid crystal. The twist angle of the liquid crystal compound from one surface to the other surface of the layer in which the liquid crystal compound is twisted and aligned is also referred to as the twist angle of the liquid crystal compound. Unless otherwise specified, Δn is the value at a wavelength of 550 nm.

[0020] <Viewing Angle Control System> The viewing angle control system of the present invention has an optically absorptive anisotropic layer, a liquid crystal cell, and a polarizer, in this order. Here, the angle between the central axis of transmittance of the optically absorptive anisotropic layer and the normal to the optically absorptive anisotropic layer is 0 to 45°. In addition, an optical compensation layer is provided between the optically absorptive anisotropic layer and the liquid crystal cell and / or between the liquid crystal cell and the polarizer, and no other optically absorptive anisotropic layer or other polarizer is provided between the optically absorptive anisotropic layer and the polarizer.

[0021] The viewing angle control system of the present invention is used as a component of an image display device, constituting the image display device of the present invention. FIG. 1 is a cross-sectional schematic diagram showing one embodiment of an image display device using the viewing angle control system of the present invention. The image display device 100a shown in FIG. 1 includes a viewing angle control system 10a and a display panel 20. Note that the side of the image display device 100a opposite the display panel 20 side of the viewing angle control system 10a is the viewing side. The viewing angle control system 10a includes, in this order from the opposite side (viewing side) to the display panel 20 side, an optically absorptive anisotropic layer 12, a liquid crystal cell 14, an optical compensation layer 18, and a polarizer 16. Note that the angle between the transmittance central axis of the optically absorptive anisotropic layer 12 and the normal to the optically absorptive anisotropic layer 12 is 0 to 45°. The liquid crystal cell 14 shown in FIG. 1 is an in-plane switching (IPS) liquid crystal cell capable of controlling the alignment direction of liquid crystal compounds in the in-plane direction. In the image display device 100a, by controlling the alignment direction of the liquid crystal compound in the liquid crystal cell 14, it is possible to switch between a light blocking mode and a transmission mode when viewed from an oblique direction at a predetermined azimuth angle.

[0022] The image display device 100a shown in FIG. 1 is switchable between a light-blocking mode and a transmission mode. FIG. 2 is a cross-sectional schematic diagram of the image display device 100a for illustrating the switchable light-blocking mode and the transmission mode. The white arrows in FIG. 2 indicate panel light emitted from the display panel 20 and emitted in an oblique direction at a predetermined azimuth angle. The configuration of the image display device 100a is the same as that shown in FIG. 1. However, in FIG. 2, the transmission axis direction A16 of the polarizer 16 is the back-to-front direction of the paper. Furthermore, the angle between the transmittance central axis of the optically absorptive anisotropic layer 12 and the normal to the optically absorptive anisotropic layer 12 is 0°. When the panel light passes through the polarizer 16, only light polarized in the back-to-front direction of the paper passes through and enters the optical compensation layer 18. Panel light incident on the optical compensation layer 18 undergoes optical transformation to compensate for the retardation, as described below, but exits the optical compensation layer 18 while maintaining its polarization direction in a substantially back-to-front direction and enters the liquid crystal cell 14. In the liquid crystal cell 14, the orientation direction (direction of the in-plane slow axis) of the liquid crystal compound is controlled to form a predetermined angle (e.g., 45°) with the polarization direction of the panel light incident on the liquid crystal cell 14. The liquid crystal compound contained in the liquid crystal cell 14 converts the panel light into light polarized in the left-to-right direction of the page and then exits the liquid crystal cell 14. Here, as described above, the angle between the transmittance central axis of the optically absorptive anisotropic layer 12 and the normal to the optically absorptive anisotropic layer 12 is 0°. That is, for light emitted obliquely, the optically absorptive anisotropic layer 12 has a low tendency to absorb light polarized in the back-to-front direction of the page, but a high tendency to absorb light polarized in the left-to-right direction of the page. In this case, panel light polarized in the left-right direction of the paper and incident on the optically absorptive anisotropic layer 12 is absorbed by the optically absorptive anisotropic layer 12 and is less likely to exit to the viewing side. In other words, the above mode is a light-blocking mode.

[0023] 2, the orientation direction of the liquid crystal compound contained in the liquid crystal cell 14 is controlled so as not to change the polarization direction of the panel light incident on the liquid crystal cell 14, thereby maintaining the polarization direction of the panel light in the direction toward the front of the page. For example, the orientation direction of the liquid crystal compound (direction of the in-plane slow axis) is controlled to form a predetermined angle (e.g., 0°) with the polarization direction of the panel light incident on the liquid crystal cell 14. In this way, light polarized in the direction toward the front of the page is not easily absorbed by the light absorption anisotropic layer 12, and the panel light is emitted toward the viewing side. In other words, the above mode is the viewing mode. Therefore, as described above, the light-blocking mode and the transmission mode can be switched by controlling the orientation direction of the liquid crystal compound contained in the liquid crystal cell 14.

[0024] Furthermore, even when the angle between the central transmittance axis of the optically absorptive anisotropic layer 12 and the normal to the optically absorptive anisotropic layer 12 is not 0°, the light-blocking mode and the transmissive mode can be switched by controlling the alignment direction of the liquid crystal compound contained in the liquid crystal cell 14 according to the above-described principle. The direction in which the central transmittance axis of the optically absorptive anisotropic layer 12 is projected from the normal to the optically absorptive anisotropic layer 12 onto the surface of the optically absorptive anisotropic layer 12 is the left-right direction on the paper. In other words, when the angle between the central transmittance axis of the optically absorptive anisotropic layer 12 and the normal to the optically absorptive anisotropic layer 12 is not 0°, the direction in which the central transmittance axis of the optically absorptive anisotropic layer 12 is projected from the normal to the optically absorptive anisotropic layer 12 onto the surface of the optically absorptive anisotropic layer 12 is perpendicular to the transmission axis direction A16 of the polarizer 16. 2 , the angle formed by the direction of the central axis of transmittance of the optically absorptive anisotropic layer 12 is a predetermined angle other than 0°. In the direction of the central axis of transmittance of the optically absorptive anisotropic layer 12, the panel light emitted from the display panel 20 is easily transmitted, making it easy to view the image displayed on the display panel 20.

[0025] 1 and 2 illustrate an embodiment of the viewing angle control system 10a having, from the side opposite the display panel 20 (the viewing side), an optically absorptive anisotropic layer 12, a liquid crystal cell 14, an optical compensation layer 18, and a polarizer 16, in this order. However, the viewing angle control system of the present invention is not limited to the above embodiment, and an optically anisotropic layer 18 may be disposed between the optically absorptive anisotropic layer 12 and the liquid crystal cell 14. The image display device of the above embodiment will be described with reference to FIG. 3. FIG. 3 is a cross-sectional schematic diagram showing one embodiment of an image display device using the viewing angle control system of the present invention. The image display device 100b shown in FIG. 3 includes the viewing angle control system 10b and a display panel 20. The viewing side of the image display device 100b is the side opposite the display panel 20 side of the viewing angle control system 10b. The viewing angle control system 10b has, in this order from the side opposite to the display panel 20 (the viewing side), an optically absorptive anisotropic layer 12, an optical compensation layer 18, a liquid crystal cell 14, and a polarizer 16. The angle between the optically absorptive anisotropic layer 12 and the normal to the optically absorptive anisotropic layer 12 is 0 to 45°.

[0026] In the above embodiment, the light-shielding mode and the light-transmitting mode can be switched by controlling the alignment direction of the liquid crystal compound contained in the liquid crystal cell 14, based on the same principle as that explained in FIGS.

[0027] 1 to 3, even if the orientation direction of the transmission axis of the polarizer 16 is different from that of the above-described embodiment, it is easily understood that the above-described light-blocking mode and transmission mode can be switched by controlling the alignment direction of the liquid crystal compound in the liquid crystal cell 14. That is, by adjusting the alignment direction of the liquid crystal compound in the liquid crystal cell 14, it is possible to emit light with a desired polarization direction, and since the polarization direction is switchable, it is possible to switch between the light-blocking mode and the transmission mode.

[0028] The above-described light-blocking mode and transmission mode can be switched by controlling the orientation direction of the liquid crystal compound contained in the liquid crystal cell 14. That is, switching between the light-blocking mode and the transmission mode is possible when viewed from an oblique direction at a predetermined azimuth angle. Here, in an image display device employing the viewing angle control system of the present invention, images are less visible in the light-blocking mode and more visible in the transmission mode. While the reason for this is not entirely clear, the inventors speculate as follows: When viewed from an oblique direction at a predetermined azimuth angle, panel light emitted in an oblique direction is handled, as described above. Optical components such as liquid crystal cells have a finite thickness, and therefore may have phase differences not only in the in-plane direction but also in the thickness direction. When light is incident from an oblique direction, the light experiences not only a phase difference in the in-plane direction but also, for example, a phase difference in the thickness direction, and undergoes polarization conversion different from that when incident from the front direction. Here, in the viewing angle control system of the present invention, since an optical compensation layer is provided between the optically absorptive anisotropic layer and the liquid crystal cell and / or between the liquid crystal cell and the polarizer, it is possible to compensate for the retardation, for example, and bring the polarization state closer to one that is easily absorbed by the optically absorptive anisotropic layer or one that is not easily absorbed by the optically absorptive anisotropic layer, which is thought to make it more difficult to view an image in the light-blocking mode and more easily viewable in the transmission mode.

[0029] The method for switching the alignment direction of the liquid crystal compound is not limited to the above embodiment, and any known method can be adopted. In the above embodiment, the liquid crystal cell 14 is an IPS-type liquid crystal cell, but a liquid crystal cell of a type described below may also be used.

[0030] In addition, in the embodiments shown in Figures 1 to 3, the optical compensation layer is disposed either between the light absorption anisotropic layer and the liquid crystal cell or between the liquid crystal cell and the polarizer. However, the optical compensation layer may be disposed between both of the above.

[0031] The viewing angle control system of the present invention does not include any other optically absorptive anisotropic layer or any other polarizer between the optically absorptive anisotropic layer and the polarizer. For example, in the embodiment shown in Fig. 1, the viewing angle control system 10a means that the liquid crystal cell 14 does not include any other polarizer, and that no other polarizer is included between the polarizer 16 and the liquid crystal cell 14, or between the optically absorptive anisotropic layer 12 and the liquid crystal cell 14. This also means that no other optically absorptive anisotropic layer is included between the liquid crystal cell 14 and the polarizer 16. At least one of another polarizer and another optically absorptive anisotropic layer may be disposed between the polarizer 16 and the display panel 20.

[0032] The configurations included in the viewing angle control system of the present invention will be described below. Note that in the embodiments shown in Figures 1 to 3 and the embodiments described above, the configurations included in the viewing angle control system can be modified as shown in the following configuration examples, and modified configurations can also be combined. In addition, hereinafter, the fact that an image is more difficult to view in the light-blocking mode will also be referred to as "excellent light-blocking," and the fact that an image is more easily viewable in the transmission mode will also be referred to as "excellent transparency."

[0033] [Light-Absorbing Anisotropic Layer] In the light-absorbing anisotropic layer included in the viewing angle control system of the present invention, the angle between the central transmittance axis of the light-absorbing anisotropic layer and the normal to the light-absorbing anisotropic layer is 0 to 45°. The light-absorbing anisotropic layer preferably contains a dichroic material. When the light-absorbing anisotropic layer contains a dichroic material, the central transmittance axis and the orientation direction of the dichroic material usually coincide. The angle can be adjusted depending on the direction in which the image is desired to be viewed. For example, when an image display device is provided with an anti-peeping function, it is preferable to maximize the transmittance in the front direction. In this case, the angle is preferably 0 to 10°. The central transmittance axis of the light-absorbing anisotropic layer may be oriented in different directions depending on the location within the plane of the light-absorbing anisotropic layer. For example, in an in-vehicle display having a curved display surface, in order to prevent light emitted from any position from being reflected on the windshield or the like and to ensure that the displayed image is properly visible to the driver, it is preferable to adjust the direction of the central axis of transmittance of the light-absorbing anisotropic layer to match the curved surface.

[0034] The term "central transmittance axis" refers to the direction in which the transmittance is highest when the transmittance is measured by varying the tilt angle (polar angle) and tilt direction (azimuthal angle) relative to the normal direction of the optically absorbing anisotropic layer surface. When measuring this angle, an AxoScan OPMF-2 (manufactured by Axometrics) is used to first detect the azimuthal angle at which the central transmittance axis is tilted. Then, in the direction of this azimuthal angle, the Mueller matrix is ​​measured while varying the polar angle to derive the transmittance. The direction in which the transmittance is highest (polar angle) is defined as the direction of the central transmittance axis of the optically absorbing anisotropic layer. This polar angle is the angle between the central transmittance axis in the optically absorbing anisotropic layer and the normal direction to the optically absorbing anisotropic layer. The transmittance central axis (polar angle) of the optically absorptive anisotropic layer is measured at 15 arbitrarily selected points in the optically absorptive anisotropic layer, and the average of the polar angles is taken as the transmittance central axis of the optically absorptive anisotropic layer. In the present invention, these optical measurements are performed using light with a wavelength of 550 nm, unless otherwise specified.

[0035] The light transmittance of the optically absorptive anisotropic layer in a direction parallel to the central axis of transmittance is preferably 50% or more, more preferably 70% or more. The upper limit of the transmittance is not particularly limited, but may be, for example, 95% or less, and is often 90% or less. The transmittance in a direction tilted 30° from the central axis of transmittance of the optically absorptive anisotropic layer is preferably 30% or less, more preferably 15% or less. The lower limit of the transmittance is not particularly limited, but may be, for example, 0.5% or more, and is often 5% or more.

[0036] The optically absorptive anisotropic layer of the present invention preferably contains at least one dichroic material (e.g., a dichroic dye). The dichroic material is not particularly limited as long as it exhibits dichroism, and examples thereof include dichroic dyes, dichroic azo dye compounds, ultraviolet-absorbing materials, infrared-absorbing materials, nonlinear optical materials, carbon nanotubes, anisotropic metal nanoparticles, and inorganic materials. The optically absorptive anisotropic layer may contain two or more dichroic materials. For example, it preferably contains a cyan dye exhibiting dichroism in the red wavelength range, a magenta dye exhibiting dichroism in the green wavelength range, and a yellow dye exhibiting dichroism in the blue wavelength range. The inclusion of multiple dichroic materials can neutralize the color and provide a viewing angle control effect across the entire wavelength range of visible light. A dichroic material is a material that exhibits dichroism, and dichroism refers to the property of varying absorbance depending on the polarization direction. The degree of orientation of the dichroic material at a wavelength of 550 nm is preferably 0.95 or greater. When the degree of orientation of the dichroic material is 0.95 or more, the transmittance in the direction of the absorption axis (i.e., the direction in which light is to be transmitted) can be increased. Furthermore, in order to achieve a neutral color, the degree of orientation of the dichroic material at a wavelength of 420 nm is preferably 0.93 or more. The thickness of the optically absorptive anisotropic layer is not particularly limited, but from the viewpoint of flexibility, it is preferably 100 to 8000 nm, and more preferably 300 to 5000 nm. Hereinafter, a dichroic dye will be described as an example of the dichroic material.

[0037] (Dichroic Dye) As the dichroic substance, a dichroic dye is preferred, and a dichroic azo dye compound is more preferred. In the present invention, a dichroic azo dye compound refers to an azo dye compound whose absorbance varies depending on the direction. A dichroic azo dye compound may or may not exhibit liquid crystallinity. When a dichroic azo dye compound exhibits liquid crystallinity, it may exhibit either a nematic liquid crystal phase or a smectic liquid crystal phase. The temperature range in which the liquid crystal phase is exhibited is preferably room temperature (approximately 20 to 28°C) to 300°C, and more preferably 50 to 200°C from the viewpoints of handleability and manufacturing suitability.

[0038] In the present invention, from the viewpoint of improving pressure resistance, it is preferable that the dichroic azo dye compound in the optically absorptive anisotropic layer-forming composition used in forming the optically absorptive anisotropic layer described below has a crosslinkable group. Specific examples of the crosslinkable group include a (meth)acryloyl group, an epoxy group, an oxetanyl group, and a styryl group, and among these, a (meth)acryloyl group is preferred.

[0039] Examples of preferred dichroic azo dye compounds for use in the present invention include a first dichroic azo dye compound, a second dichroic azo dye compound, and a third dichroic azo dye compound. The first dichroic azo dye compound is a dichroic azo dye compound having a maximum absorption wavelength in the wavelength range of 560 nm to 700 nm. The second dichroic azo dye compound is a dichroic azo dye compound having a maximum absorption wavelength in the wavelength range of 455 nm to less than 560 nm. The third dichroic azo dye compound is a dichroic azo dye compound having a maximum absorption wavelength in the wavelength range of 380 nm to 455 nm. Specific examples of the first dichroic azo dye compound, the second dichroic azo dye compound, and the third dichroic azo dye compound include, for example, the compounds described in paragraphs

[0161] to

[0171] of WO 2022 / 138548, the compounds described in paragraphs

[0172] to

[0180] of WO 2022 / 138548, and the compounds described in paragraphs

[0183] to

[0206] of WO 2022 / 138548.

[0040] The content of the dichroic material is preferably from 1 to 30% by mass, more preferably from 5 to 25% by mass, and even more preferably from 10 to 20% by mass, based on the total solid mass of the light absorption anisotropic layer.

[0041] (Liquid Crystal Compound) The optically absorptive anisotropic layer is preferably formed using a liquid crystal composition containing a dichroic substance and a liquid crystal compound. Therefore, the optically absorptive anisotropic layer preferably contains a component derived from the liquid crystal compound. By forming the optically absorptive anisotropic layer using the liquid crystal composition, the dichroic substance can be aligned with a high degree of orientation while preventing precipitation of the dichroic substance. As the liquid crystal compound, either a low-molecular-weight liquid crystal compound or a high-molecular-weight liquid crystal compound can be used, and it is also preferable to use both in combination. Here, "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound that does not have a repeating unit in its chemical structure. Furthermore, "high-molecular-weight liquid crystal compound" refers to a liquid crystal compound that has a repeating unit in its chemical structure.

[0042] The low-molecular-weight liquid crystal compound may be either a compound exhibiting a nematic liquid crystal phase or a compound exhibiting a smectic liquid crystal phase, but from the viewpoint of increasing the degree of orientation, a compound exhibiting a smectic liquid crystal phase is preferred. For example, the liquid crystal compounds described in JP-A-2013-228706 can be mentioned.

[0043] Examples of polymeric liquid crystalline compounds include the thermotropic liquid crystalline polymers described in JP 2011-237513 A. Furthermore, from the viewpoint of excellent strength (particularly the flex resistance of the film), the polymeric liquid crystalline compound preferably has a repeating unit having a crosslinkable group at its terminal. Examples of crosslinkable groups include the polymerizable groups described in paragraphs

[0040] to

[0050] of JP 2010-244038 A. Among these, from the viewpoint of improving reactivity and synthetic suitability, acryloyl groups, methacryloyl groups, epoxy groups, oxetanyl groups, and styryl groups are preferred, with acryloyl groups and methacryloyl groups being more preferred.

[0044] When the light absorption anisotropic layer contains a polymeric liquid crystalline compound, the polymeric liquid crystalline compound preferably forms a nematic liquid crystalline phase. The temperature range in which the polymeric liquid crystalline compound exhibits the nematic liquid crystalline phase is preferably from room temperature (23°C) to 450°C, and from the viewpoints of handling and manufacturing suitability, preferably from 50 to 400°C.

[0045] The content of the component derived from the liquid crystal compound in the light absorption anisotropic layer is preferably 25 to 2,000 parts by mass, more preferably 100 to 1,300 parts by mass, and even more preferably 200 to 900 parts by mass, relative to 100 parts by mass of the dichroic substance. When the content of the liquid crystal compound is within the above range, the degree of orientation of the dichroic substance is further improved. The liquid crystal compound may be contained alone, or two or more types may be contained. When two or more types of liquid crystal compounds are contained, the content of the component derived from the liquid crystal compound means the total content of the liquid crystal compounds.

[0046] (Additives) The liquid crystal composition used for forming the light absorption anisotropic layer may further contain additives such as a solvent, a vertical alignment agent, an interfacial improver, a leveling agent, a polymerizable component, a polymerization initiator (e.g., a radical polymerization initiator), a durability improver, etc. Known additives can be used as appropriate.

[0047] The viewing angle control system of the present invention may include another layer different from the optically absorbing anisotropic layer and the layer described below. However, the other layer is a layer that is in direct contact with the optically absorbing anisotropic layer or indirectly in contact with the optically absorbing anisotropic layer via a layer different from the optically absorbing anisotropic layer and the layer described below. Hereinafter, the other layer that is in direct or indirect contact with the optically absorbing anisotropic layer will be described.

[0048] (Substrate Layer) The viewing angle control system of the present invention may include a substrate layer as another layer. The substrate layer is not particularly limited, but a transparent film or sheet is preferred. Known transparent resin films, transparent resin plates, transparent resin sheets, glass, and the like can be used. Examples of transparent resin films that can be used include cellulose acylate films (e.g., cellulose triacetate films, cellulose diacetate films, cellulose acetate butyrate films, and cellulose acetate propionate films), polyethylene terephthalate films, polyethersulfone films, polyacrylic resin films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, and (meth)acrylonitrile films. Among these, cellulose acylate films are preferred because they have high transparency, low optical birefringence, and are easy to manufacture. These films are commonly used as protective films for polarizers, and cellulose triacetate films are particularly preferred. The thickness of the transparent resin film is preferably 20 μm to 100 μm.

[0049] (Alignment Film) The viewing angle control system of the present invention may have an alignment film between the substrate layer and the light-absorbing anisotropic layer as another layer. The alignment film may be any layer that can align the dichroic substance (liquid crystal compound) in a desired state on the alignment film. For example, a film formed from a polyfunctional acrylate compound or polyvinyl alcohol may be used. Polyvinyl alcohol is particularly preferred. The alignment film may be a photo-alignment film. Note that by irradiating a photo-alignment film containing an azo compound or a cinnamoyl compound with UV light from an oblique direction, the dichroic substance can be aligned at an angle relative to the normal direction of the film.

[0050] (Barrier Layer) The viewing angle control system of the present invention may include a barrier layer as another layer. Here, the barrier layer is also called a gas barrier layer (oxygen barrier layer), and has the function of protecting the light absorption anisotropic layer from gases such as oxygen in the atmosphere, moisture, or compounds contained in adjacent layers. For details of the barrier layer, see, for example, paragraphs

[0014] to

[0054] of JP 2014-159124 A, paragraphs

[0042] to

[0075] of JP 2017-121721 A, paragraphs

[0045] to

[0054] of JP 2017-115076 A, paragraphs

[0010] to

[0061] of JP 2012-213938 A, and paragraphs

[0021] to

[0031] of JP 2005-169994 A.

[0051] (Refractive Index Adjustment Layer) The optically absorptive anisotropic layer may have a problem of internal reflection due to its high refractive index. In such a case, a refractive index adjustment layer may be used. The refractive index adjustment layer is preferably disposed in contact with the optically absorptive anisotropic layer and serves as a layer for so-called index matching. The in-plane average refractive index of the refractive index adjustment layer at a wavelength of 550 nm is preferably 1.55 or more and 1.70 or less.

[0052] (Method for forming optically absorbing anisotropic layer) The method for forming the optically absorbing anisotropic layer is not particularly limited, and examples thereof include a method including, in this order, a step of applying a composition for forming an optically absorbing anisotropic layer to form a coating film (hereinafter also referred to as a "coating film forming step") and a step of orienting a liquid crystalline component and a dichroic substance contained in the coating film (hereinafter also referred to as an "orientation step"). Note that the liquid crystalline component is a component that includes not only the above-mentioned liquid crystalline compound, but also the dichroic substance having liquid crystallinity, if the above-mentioned dichroic substance has liquid crystallinity.

[0053] -Coating film forming step- The coating film forming step is a step of forming a coating film by applying a composition for forming an optically absorbing anisotropic layer. The composition for forming an optically absorbing anisotropic layer can be easily applied by using a composition for forming an optically absorbing anisotropic layer that contains a solvent, or by using a composition for forming an optically absorbing anisotropic layer that has been converted into a liquid such as a molten liquid by heating or the like. Specific examples of methods for applying the composition for forming an optically absorbing anisotropic layer include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0054] Orientation Process—The orientation process is a process for orienting the liquid crystalline component contained in the coating film. This results in an optically absorptive anisotropic layer. The orientation process may include a drying process. Components such as the solvent can be removed from the coating film by the drying process. The drying process may be performed by leaving the coating film at room temperature for a predetermined time (e.g., natural drying), or by heating and / or blowing air. Here, the liquid crystalline component contained in the composition for forming an optically absorptive anisotropic layer may be aligned by the above-described coating film formation process or drying process. For example, in an embodiment in which the composition for forming an optically absorptive anisotropic layer is prepared as a coating liquid containing a solvent, the coating film is dried to remove the solvent from the coating film, thereby obtaining a coating film with optical absorptive anisotropy (i.e., an optically absorptive anisotropic layer). When the drying process is performed at a temperature equal to or higher than the temperature at which the liquid crystalline component contained in the coating film transitions from a liquid crystal phase to an isotropic phase, the heat treatment described below may not be performed.

[0055] The transition temperature from the liquid crystal phase to the isotropic phase of the liquid crystalline component contained in the coating film is preferably 10 to 250°C, more preferably 25 to 190°C, from the viewpoint of manufacturability, etc. A transition temperature of 10°C or higher is preferred because it eliminates the need for a cooling process or the like to lower the temperature to a temperature range in which the liquid crystal phase is exhibited. Furthermore, a transition temperature of 250°C or lower is preferred because it does not require a high temperature even when heating to an isotropic phase in order to suppress alignment defects, thereby reducing waste of thermal energy and deformation and deterioration of the substrate.

[0056] The orientation step preferably includes a heat treatment. This allows the liquid crystalline component contained in the coating film to be oriented, and the heat-treated coating film can be suitably used as a light absorption anisotropic layer. From the viewpoint of manufacturability, the heat treatment is preferably performed at a temperature of 10 to 250°C, more preferably 25 to 190°C. The heating time is preferably 1 to 300 seconds, more preferably 1 to 60 seconds.

[0057] The alignment step may include a cooling treatment carried out after the heating treatment. The cooling treatment is a treatment in which the coated film after heating is cooled to about room temperature (20 to 25°C). This makes it possible to fix the alignment of the liquid crystalline component contained in the coated film. The cooling method is not particularly limited and can be carried out by a known method.

[0058] Other Steps The method for forming the optically absorbing anisotropic layer may include a step of curing the optically absorbing anisotropic layer (hereinafter also referred to as a "curing step") after the above-described alignment step. For example, when the compound contained in the optically absorbing anisotropic layer has a crosslinkable group (polymerizable group), the curing step is performed by heating and / or light irradiation (exposure). Among these, from the viewpoint of productivity, the curing step is preferably performed by light irradiation. Various light sources, such as infrared light, visible light, or ultraviolet light, can be used as the light source for curing, but ultraviolet light is preferred. Furthermore, ultraviolet light may be irradiated while heating during curing, or ultraviolet light may be irradiated through a filter that transmits only specific wavelengths. When exposure is performed while heating, the heating temperature during exposure is preferably 25 to 140°C, although this depends on the transition temperature of the liquid crystal component contained in the liquid crystal film. Furthermore, exposure may be performed under a nitrogen atmosphere. When the curing of the liquid crystal film proceeds by radical polymerization, exposure under a nitrogen atmosphere is preferred because inhibition of polymerization by oxygen is reduced.

[0059] The optically absorptive anisotropic layer may contain a dichroic dye and a guest-host liquid crystal material, and may be capable of electrically driving the alignment direction of the dichroic dye, as described in, for example, JP-A No. 2013-541727. In this case, it becomes possible to electrically switch the alignment direction of the dichroic dye.

[0060] [Liquid Crystal Cell] The liquid crystal cell included in the viewing angle control system of the present invention is disposed between the light absorption anisotropic layer and the polarizer, and switches between a light-blocking mode and a transmission mode by controlling the alignment direction of the liquid crystal compound included in the liquid crystal cell. The liquid crystal cell is not particularly limited as long as it can switch between a light-blocking mode and a transmission mode, and any known liquid crystal cell can be used. The liquid crystal cell may have multiple regions in which the alignment direction of the liquid crystal compound can be controlled. When the liquid crystal cell has multiple regions in which the alignment direction of the liquid crystal compound can be controlled, it is possible to independently control the alignment direction of the liquid crystal compound in each region and switch between a light-blocking mode and a transmission mode for the regions of the display panel corresponding to each region.

[0061] The type of the liquid crystal cell is not particularly limited, and any known type can be used. Examples of the type of the first liquid crystal cell include the IPS type described above, a twisted nematic (TN) type, a vertical alignment (VA) type, an electrically controlled birefringence (ECB) type, and an optically compensated bend (OCB) type. The liquid crystal cell may be of the STN (Super Twisted Nematic) type having a twist angle of 180° or more, or the VATN (Vertically Aligned Twisted Nematic) type disclosed in Japanese Patent Laid-Open No. 10-123576, in which rod-shaped liquid crystal molecules are substantially vertically aligned when no voltage is applied and the liquid crystal layer is twisted at 60 to 120° when a voltage is applied. Of these, the liquid crystal cell type is preferably selected from the group consisting of the TN type, the IPS type, the ECB type, and the VA type, and the IPS type is preferred.

[0062] In TN liquid crystal cells, when no voltage is applied, rod-shaped liquid crystal molecules are aligned substantially horizontally and are further aligned in a twisted manner at an angle of 60 to 120 degrees along the thickness direction. TN liquid crystal cells are most commonly used as color TFT (Thin Film Transistor) liquid crystal display devices, and are described in numerous literature.

[0063] In VA-mode liquid crystal cells, rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied. VA-mode liquid crystal cells include (1) narrowly defined VA-mode liquid crystal cells (described in Japanese Patent Laid-Open No. 2-176625) in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and substantially horizontally when voltage is applied, as well as (2) multi-domain VA-mode (MVA-mode) liquid crystal cells (described in SID97, Digest of Tech. Papers (Proceedings) 28 (1997) 845), (3) n-ASM-mode liquid crystal cells in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and aligned in a twisted multi-domain manner when voltage is applied (described in Proceedings of the Japan Liquid Crystal Symposium 58-59 (1998)), and (4) SURVIVAL-mode liquid crystal cells (presented at LCD International 98). In addition, any of a PVA (Patterned Vertical Alignment) method, an optical alignment method, and a PSA (Polymer-Sustained Alignment) method may be used. Details of these methods are described in detail in JP-A-2006-215326 and JP-A-2008-538819.

[0064] In an IPS liquid crystal cell, rod-shaped liquid crystal molecules are aligned substantially parallel to the substrates, and when a voltage is applied between the electrodes to generate an electric field parallel to the substrate surfaces, the liquid crystal molecules respond in a planar manner.

[0065] In ECB liquid crystal cells, an electric field is generated perpendicular to the substrate surface, and the alignment direction of the liquid crystal molecules is changed by the electric field. In ECB liquid crystal cells, the liquid crystal molecules generally align along the thickness direction of the cell when an electric field is generated.

[0066] When the liquid crystal cell is of an IPS mode, the in-plane retardation (Re(550)) of the liquid crystal cell is preferably 100 to 500 nm, more preferably 120 to 450 nm. When the liquid crystal cell is of an IPS mode, the alignment direction of the liquid crystal compound can be controlled in the in-plane direction, and it is preferable that the angle between the absorption axis of the polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to at least 0 to 5° or 85 to 95°. When the alignment direction of the liquid crystal compound is controlled within the above range, it is possible to emit light from the polarizer without changing its polarization state. When the liquid crystal cell is of an IPS mode, when the polarization direction of light emitted from the polarizer is changed by the liquid crystal cell, the angle between the absorption axis of the polarizer and the in-plane slow axis of the liquid crystal cell can be appropriately adjusted depending on the in-plane retardation value of the liquid crystal cell. When the polarization direction is changed, the angle between the absorption axis of the polarizer and the in-plane slow axis of the liquid crystal cell is preferably controllable to 15 to 75°, more preferably 20 to 70°. In terms of superiority in at least one of light-blocking property and transmittance, the angle is more preferably 20 to 40° or 50 to 70°, and particularly preferably 20 to 30° or 60 to 70°.

[0067] When the liquid crystal cell is of the IPS mode, it is preferable that the following requirement 1 or requirement 2 is satisfied. Requirement 1: The in-plane retardation (Re(550)) of the IPS mode liquid crystal cell at a wavelength of 550 nm is 300 to 450 nm. Requirement 2: The IPS mode liquid crystal cell is switchable between two states, and in one of the two states, the angle between the in-plane slow axis of the liquid crystal cell and the absorption axis of the polarizer is 0 to 5° or 85 to 95°, and in the other of the two states, the angle between the in-plane slow axis of the liquid crystal cell and the absorption axis of the polarizer is 20 to 35°.

[0068] When the liquid crystal cell is of the VA mode or ECB mode, it is preferable that the following requirements 3 and 4 be satisfied. Furthermore, it is more preferable that the following requirements 3, 4, and 5 be satisfied. Requirement 3: The VA mode or ECB mode liquid crystal cell has a Δnd of 500 to 900 nm at a wavelength of 550 nm. Requirement 4: The VA mode or ECB mode liquid crystal cell is switchable between two states, and in one of the two states, the angle between the in-plane slow axis of the liquid crystal cell and the absorption axis of the polarizer is 0 to 10°. Requirement 5: In one of the two states in the above requirement 4, the voltage of the liquid crystal cell is 1.5 to 3.5 V, and in the other of the two states, the voltage is OFF.

[0069] The liquid crystal cell may be capable of controlling the liquid crystal molecules to a state intermediate between the light-blocking mode and the transmissive mode (grayscale display). That is, the liquid crystal cell may control the alignment direction of the liquid crystal molecules to a state intermediate between the alignment direction of the liquid crystal molecules in the light-blocking mode and the alignment direction of the liquid crystal molecules in the transmissive mode. During grayscale display, the liquid crystal molecules are aligned in a predetermined direction. Therefore, the magnitude of birefringence caused by the liquid crystal molecules when observed obliquely differs between the alignment direction and the direction perpendicular to the alignment direction, resulting in differences in brightness and color tone. Here, a region of the liquid crystal cell in which the alignment direction of the liquid crystal molecules can be controlled (e.g., a region corresponding to a single pixel of a display panel) may be further divided into multiple regions, known as a multi-domain structure. The multi-domain structure averages the viewing angle characteristics of brightness and color tone, making it easier to reduce differences in brightness and color tone. Specifically, by averaging each of the above-mentioned regions of the liquid crystal cell (e.g., a region corresponding to a single pixel) into two or more regions with different initial alignment states of the liquid crystal molecules, the viewing angle-dependent bias in brightness and color tone can be reduced. Furthermore, the same effect can be obtained by configuring each of the above-mentioned regions with two or more different regions in which the alignment direction of the liquid crystal compound changes continuously under applied voltage.

[0070] In any of the liquid crystal cell modes described above, the region of the liquid crystal cell (e.g., a region corresponding to a single pixel) may be divided into a plurality of regions, which is called a multi-domain structure. The multi-domain structure is preferable because it averages the viewing angle characteristics in the vertical and horizontal directions, etc., and improves the display quality.

[0071] [Optical Compensation Layer] The viewing angle control system of the present invention has an optical compensation layer between the light absorption anisotropic layer and the liquid crystal cell, and at least one between the liquid crystal cell and the polarizer. The optical compensation layer preferably exhibits a thickness direction retardation (Rth). The absolute value of Rth of the optical compensation layer is preferably 50 nm or more, more preferably 100 nm or more. The absolute value of Rth of the optical compensation layer is preferably 600 nm or less, more preferably 500 nm or less. The in-plane retardation (Re) of the optical compensation layer is preferably 0 nm or more, more preferably 3 nm or more. The Re of the optical compensation layer is preferably 300 nm or less, more preferably 250 nm or less. The Nz factor of the optical compensation layer is preferably -100 to 100, more preferably -75 to 75. Here, the Nz factor refers to a value expressed as Nz = (nx - nz) / (nx - ny). The optical compensation layer is preferably an A plate, a B plate or a C plate, more preferably a B plate or a C plate, and even more preferably a B plate.

[0072] There are two types of A plates: positive A plates (positive A plates, +A plates) and negative A plates (negative A plates, -A plates). When the refractive index in the in-plane slow axis direction of the film is nx, the refractive index in the in-plane direction perpendicular to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, the positive A plate satisfies the relationship of formula (A1), and the negative A plate satisfies the relationship of formula (A2). Note that the positive A plate exhibits a positive Rth value, while the negative A plate exhibits a negative Rth value. Note that the in-plane slow axis direction of the film is the direction in which the in-plane refractive index is maximum. Formula (A1) nx>ny≒nz Formula (A2) ny<nx≒nz Note that the above "≒" encompasses not only the case where both are completely identical, but also the case where both are substantially identical. The term "substantially the same" means that, for example, "ny ≒ nz" includes cases where (ny - nz) x d is -10 to 10 nm, preferably -5 to 5 nm, and "nx ≒ nz" also includes cases where (nx - nz) x d is -10 to 10 nm, preferably -5 to 5 nm. In (ny - nz) x d, d is the thickness of the film.

[0073] B plates have different values ​​for nx, ny, and nz. There are two types of B plates: a B plate with a negative Rth that satisfies the relationship of formula (B1), and a B plate with a positive Rth that satisfies the relationship of formula (B2). Formula (B1) (nx+ny) / 2>nz Formula (B2) (nx+ny) / 2<nz

[0074] There are two types of C plates: positive C plates (positive C plates, +C plates) and negative C plates (negative C plates, -C plates). Positive C plates satisfy the relationship of formula (C1), while negative C plates satisfy the relationship of formula (C2). Note that a positive C plate exhibits a negative Rth value, while a negative C plate exhibits a positive Rth value. Formula (C1) nz>nx≒ny Formula (C2) nz<nx≒ny Note that the above "≒" encompasses not only the case where both are completely identical, but also the case where both are substantially identical. "Substantially the same" means, for example, that "nx≒ny" also includes the case where (nx-ny)×d is 0 to 10 nm, preferably 0 to 5 nm. Note that in (ny-nz)×d, d is the film thickness.

[0075] The values ​​of Re, Rth, and Nz factor of the optical compensation layer can be adjusted as appropriate depending on the characteristics of the liquid crystal cell used. Preferred combinations of the characteristics of the liquid crystal cell used and the characteristics of the optical compensation layer (first to ninth embodiments) will be described below. Note that in each embodiment described below, only the values ​​of Re and Nz factor are shown, but the following relationship holds between Rth, Re, and Nz factor. Note that in the following formula, Nz represents the value of the Nz factor: Rth=Re(Nz-0.5)

[0076] (First Aspect) In the first aspect, the liquid crystal cell is of an IPS mode, and the Re of the liquid crystal cell is 250 to 300 nm. In the liquid crystal cell of the first aspect, the angle between the absorption axis of a polarizer (described later) and the in-plane slow axis of the liquid crystal cell can be controlled to a state of 85 to 95° or a state of 40 to 50°. In the first aspect, the optical compensation layer preferably satisfies the following relationships (1A) and (1B), and more preferably satisfies the following relationships (1C) and (1D). (1A) 125 nm ≦ Re ≦ 250 nm (1B) −0.2 ≦ Nz ≦ 1.6 (1C) 175 nm ≦ Re ≦ 250 nm (1D) −0.2 ≦ Nz ≦ 1.2

[0077] (Second Aspect) In the second aspect, the liquid crystal cell is of an IPS mode, and the Re of the liquid crystal cell is 250 to 300 nm. In the liquid crystal cell of the third aspect, the angle between the absorption axis of a polarizer (described later) and the in-plane slow axis of the liquid crystal cell can be controlled to 85 to 95° or 40 to 50°. In the second aspect, the optical compensation layer preferably satisfies the following relationships (2A) and (2B), and more preferably satisfies the following relationships (2C) and (2D). (2A) 50 nm ≦ Re ≦ 200 nm (2B) 2.0 ≦ Nz ≦ 8.0 (2C) 100 nm ≦ Re ≦ 200 nm (2D) 2.0 ≦ Nz ≦ 6.5

[0078] (Third Aspect) In the third aspect, the liquid crystal cell is of an IPS mode, and the Re of the liquid crystal cell is 115 to 165 nm. In the liquid crystal cell of the third aspect, the angle between the absorption axis of a polarizer (described later) and the in-plane slow axis of the liquid crystal cell can be controlled to a state of 85 to 95° or a state of 40 to 50°. In the third aspect, the optical compensation layer preferably satisfies the following relationships (3A) and (3B), and more preferably satisfies the following relationships (3C) and (3D). Note that satisfying the relationship (3B) or (3D) means satisfying either one of the inequalities described in the following relationships. (3A) 0 nm ≦ Re ≦ 60 nm (3B) Nz ≦ -0.3, 1.3 ≦ Nz (3C) 0 nm ≦ Re ≦ 30 nm (3D) Nz ≦ -2.8, 3.8 ≦ Nz

[0079] (Fourth Aspect) In the fourth aspect, the liquid crystal cell is of an IPS mode, and the Re of the liquid crystal cell is 375 to 425 nm. In the liquid crystal cell of the fourth aspect, the angle between the absorption axis of a polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to be 85 to 95° or 40 to 50°. In the fourth aspect, the optical compensation layer preferably satisfies the following relationships (4A) and (4B), and more preferably satisfies the following relationships (4C) and (4D). Note that satisfying relationship (4B) or (4D) means satisfying either one of the inequalities described in the following relationships. (4A) 0nm ≦ Re ≦ 125nm (4B) Nz ≦ -0.3, 1.3 ≦ Nz (4C) 0nm ≦ Re ≦ 100nm (4D) Nz ≦ -0.5, 1.5 ≦ Nz

[0080] (Fifth Aspect) In the fifth aspect, the liquid crystal cell is of an IPS mode, and has an Re of 250 to 300 nm. In the liquid crystal cell of the fifth aspect, the angle between the absorption axis of a polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to be 85 to 95° or 20 to 35°. In the fifth aspect, the optical compensation layer preferably satisfies the following relationships (5A) and (5B), more preferably satisfies the following relationships (5C) and (5D), and even more preferably satisfies the following relationships (5E) and (5F). (5A) 20nm≦Re≦250nm (5B) -5.0≦Nz≦10.0 (5C) 100nm≦Re≦250nm (5D) 0.5≦Nz≦5.0 (5E) 125nm≦ Re≦250nm (5F) 0.5≦Nz≦1.5

[0081] (Sixth Aspect) In the sixth aspect, the liquid crystal cell is of an IPS mode, and the Re of the liquid crystal cell is 325 to 375 nm. In the liquid crystal cell of the sixth aspect, the angle between the absorption axis of a polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to be 85 to 95° or 20 to 35°. In the sixth aspect, the optical compensation layer preferably satisfies the following relationships (6A) and (6B), more preferably satisfies the following relationships (6C) and (6D), and more preferably satisfies the following relationships (6E) and (6F). (6A) 125nm≦Re≦250nm (6B) 1.5≦Nz≦4.1 (6C) 150nm≦Re≦250nm (6D) 1.5≦Nz≦3.0 (6E) 175nm≦ Re≦250nm (6F) 1.6≦Nz≦2.5

[0082] (Seventh Aspect) In the seventh aspect, the liquid crystal cell is a VA mode or an ECB mode, and the Δnd of the liquid crystal cell is 210 to 300 nm. In the liquid crystal cell of the seventh aspect, the angle between the absorption axis of a polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to a state of 35 to 55° (horizontal alignment mode), and the alignment direction of the liquid crystal compound in the liquid crystal cell can be controlled to a state parallel to the thickness direction of the liquid crystal cell (vertical alignment mode). In the seventh aspect, the optical compensation layer preferably satisfies the following relationships (7A) and (7B), and more preferably satisfies the following relationships (7C) and (7D). It is also preferable that the following relationships (7C) and (7E) are satisfied. (7A) 125nm≦Re≦250nm (7B) 1.5≦Nz≦6.5 (7C) 150nm≦Re≦225nm (7D) 2.5≦Nz≦4.5 (7E) 2.5≦ Nz≦3.0

[0083] (Eighth Aspect) In the eighth aspect, the liquid crystal cell is a VA mode or an ECB mode, and Δnd of the liquid crystal cell is 210 to 300 nm. In the liquid crystal cell of the eighth aspect, the angle between the absorption axis of a polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to a state of 35 to 55° (horizontal alignment mode), and the alignment direction of the liquid crystal compound in the liquid crystal cell can be controlled to a state parallel to the thickness direction of the liquid crystal cell (vertical alignment mode). In the eighth aspect, the optical compensation layer preferably satisfies the following relationships (8A) and (8B), and more preferably satisfies the following relationships (8C) and (8D). Note that satisfying the relationships (8B) and (8D) means satisfying either one of the inequalities described in the following relationships. (8A) 50nm≦Re≦200nm (8B) -7.5≦Nz≦1.0 (8C) 75nm≦Re≦150nm (8D) -4.0≦Nz≦1.0

[0084] (Ninth Aspect) In the ninth aspect, the liquid crystal cell is a VA mode or an ECB mode, and the Δnd of the liquid crystal cell is 500 to 900 nm. In the liquid crystal cell of the ninth aspect, the angle between the absorption axis of a polarizer described below and the in-plane slow axis of the liquid crystal cell can be controlled to a state of 0 to 10° or 80 to 100° (horizontal alignment mode), and the alignment direction of the liquid crystal compound in the liquid crystal cell can be controlled to a state parallel to the thickness direction of the liquid crystal cell (vertical alignment mode). In the ninth aspect, the optical compensation layer preferably satisfies the following relationships (9A) and (9B), and more preferably satisfies the following relationships (9C) and (9D). It is also preferable that the optical compensation layer satisfies the following relationships (9C) and (9E). Note that satisfying relationship (9B) or (9D) means satisfying either one of the inequalities described in the following relationships. (9A) 50nm ≦ Re ≦ 200nm (9B) Nz ≦ -0.5, 1.5 ≦ Nz (9C) 75nm ≦ Re ≦ 150nm (9D) -7.5 ≦ Nz ≦ -1.0, 2.0 ≦ Nz ≦ 8.5 (9E) 2.0 ≦ Nz ≦ 2.3

[0085] In the ninth embodiment, the liquid crystal cell is preferably multi-domain. In the multi-domain liquid crystal cell, the alignment direction of the liquid crystal compound in the liquid crystal cell differs between one domain and the other domain, but the alignment direction of the liquid crystal compound may change continuously between the domains.

[0086] When the optical compensation layer has an in-plane slow axis, it is preferable to adjust the orientation relationship so that the angle between the direction of the in-plane slow axis of the optical compensation layer and the direction of the absorption axis of the polarizer is 0±5° or 90±5°.

[0087] [Polarizer] The polarizer included in the viewing angle control system of the present invention is not particularly limited, and a known polarizer (linear polarizer) can be used. For example, examples of linear polarizers (absorbing polarizers) include polarizers in which a dichroic substance is dyed onto polyvinyl alcohol or other polymer resin and stretched to align it horizontally, and polarizers in which a dichroic substance is oriented horizontally by utilizing the alignment properties of liquid crystals.

[0088] The polarizer may be a reflective polarizer or a laminate of an absorbing polarizer and a reflective polarizer. A reflective polarizer is a polarizer that reflects one polarized light and transmits the other polarized light. Note that a reflective polarizer has a reflection axis and a transmission axis in its plane, but the reflection axis functions similarly to the absorption axis in a normal polarizer (absorption polarizer) in the sense that it does not transmit polarized light in that direction. Therefore, in this specification, the reflection axis of a reflective polarizer can be read as the absorption axis.

[0089] [Other Layers] The viewing angle control system of the present invention may include layers (other layers) other than those described above. Examples of the other layers include a protective film, an adhesive layer, an adhesive layer, a diffusion sheet, a prism sheet, and a reflection sheet. Known layers can be used as the other layers.

[0090] <Image Display Device> The image display device of the present invention includes the viewing angle control system of the present invention. The image display device is not particularly limited, and examples thereof include a liquid crystal display device, an electroluminescence display device, and a plasma display device. The image display device may be used, for example, as a display, a head-up display, a head-mounted display, etc. The image display device of the present invention may be used in combination with a configuration commonly used in this field. For example, the image display device of the present invention may be combined with a protective film, a depolarizing film, an optical compensation film, etc.

[0091] As shown in Figures 1 and 2, the image display device of the present invention includes a viewing angle control system and a display panel. Examples of the display panel include a display panel using a liquid crystal display element, an electroluminescent display element, or a plasma display element. When a liquid crystal display element is used as the display element, it may be equipped with a backlight, or it may be a transmissive liquid crystal display element without a backlight. Examples of the electroluminescent display element include an organic electroluminescent (organic EL) display element, an inorganic electroluminescent (inorganic EL) display element, and a light-emitting diode display element, with an organic EL display element or a light-emitting diode display element being preferred.

[0092] As described above, the image display device of the present invention can switch between a light-blocking mode and a transmission mode when viewed from an oblique direction at a predetermined azimuth angle. Furthermore, the image display device of the present invention has excellent light-blocking and transmission properties. Due to the above characteristics, the image display device of the present invention can be used as an image display device capable of changing visibility from an oblique direction at a predetermined azimuth angle. For example, when the image display device of the present invention is applied to an in-vehicle display, by setting the predetermined azimuth angle to the driver's side, it is possible to switch whether or not an image displayed on the display panel is visible when viewed from the driver's side. It is also preferable that the above switching be controlled based on the driving state of the vehicle. The image display device can also be preferably applied to image display devices for mobile applications (e.g., laptop PCs, smartphones, tablet devices, portable game consoles, etc.).

[0093] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0094] Example 1 A laminate was obtained in the following procedure, and an image display device used in Example 1 was produced. [Preparation of Optical Film 1] Optical film 1 having a light absorption anisotropic layer was produced in the following procedure.

[0095] (Formation of Alignment Film Layer) The following composition for forming an alignment film 1 was applied to the surface of a commercially available cellulose acylate film (manufactured by Fujifilm Corporation, product name Fujitac TG60UL) using a wire bar. The support on which the coating film was formed was dried with hot air at 140°C for 120 seconds to form an alignment film AL1, thereby obtaining an alignment film-coated cellulose acylate film 1. The thickness of the alignment film AL1 was 1 μm.

[0096] ------------------------------------------------------------------ Composition 1 for forming alignment film -------------------------------------------------- Polymer PA-1 (described below) 100.00 parts by mass Acid generator PAG-1 (described below) 8.25 parts by mass Stabilizer DIPEA (described below) 0.6 parts by mass Butyl acetate 1001.42 parts by mass Methyl ethyl ketone 250.36 parts by mass

[0097] Polymer PA-1 (wherein the numerical value for each repeating unit represents the content (% by mass) of each repeating unit relative to all repeating units)

[0098] Acid generator PAG-1

[0099] Stabilizer DIPEA

[0100] (Formation of Optically Absorbent Anisotropic Layer A1) The following composition for forming an optically absorbent anisotropic layer P1 was continuously applied onto the obtained cellulose acylate film 1 with an alignment layer using a wire bar, heated at 120°C for 60 seconds, and then cooled to room temperature (23°C). Next, the composition was heated at 85°C for 60 seconds and cooled again to room temperature. Thereafter, an LED lamp (center wavelength 365 nm) was used to illuminate the layer from the direction normal to the film at an illuminance of 200 mW / cm. ２ The optically absorptive anisotropic layer A1 was formed on the alignment film AL1 by irradiating the alignment film AL1 with light for 2 seconds under the irradiation conditions of: The thickness of the optically absorptive anisotropic layer A1 was 4.5 μm.

[0101] 0.17 parts by mass of dichroic substance D-2 below; 1.13 parts by mass of dichroic substance D-3 below; 8.67 parts by mass of polymer liquid crystal compound P-1 below; 1.97 parts by mass of liquid crystal compound L-1 below; 0.20 parts by mass of IRGACURE OXE-02 (manufactured by BASF); 0.16 parts by mass of alignment agent E-1 below; 0.16 parts by mass of alignment agent E-2 below; 0.007 parts by mass of surfactant F-2 below; 78.17 parts by mass of cyclopentanone; 8.69 parts by mass of benzyl alcohol ----------------------------------------------------------------------------------

[0102] Dichroic substance D-1

[0103] Dichroic substance D-2

[0104] Dichroic substance D-3

[0105] Polymer liquid crystal compound P-1

[0106] Liquid crystal compound L-1 [a mixture of the following liquid crystal compounds (RA), (RB) and (RC) in a mass ratio of 84:14:2]

[0107] Orientation agent E-1

[0108] Orientation agent E-2

[0109] Surfactant F-2 (In the following formula, TMS represents a trimethylsilyl group.)

[0110] (Formation of Protective Layer B1) The following protective layer-forming composition B1 was continuously applied to the obtained optically absorptive anisotropic layer A1 using a wire bar to form a coating film. The support on which the coating film had been formed was then dried with hot air at 60°C for 60 seconds and then with hot air at 100°C for 120 seconds to form a protective layer B1, thereby producing an optical film 1 having an optically absorptive anisotropic layer. The thickness of the protective layer was 0.5 μm.

[0111] -------------------------------------------------- Protective layer forming composition B1 -------------------------------------------------- 3.80 parts by mass of modified polyvinyl alcohol PVA-1 shown below 0.20 parts by mass IRGACURE 2959 0.08 parts by mass of dye compound G-1 shown below Water 70 parts by mass Methanol 30 parts by mass --------------------------------------------------

[0112] Modified polyvinyl alcohol PVA-1

[0113] Pigment compound G-1

[0114] [Preparation of Laminated Optical Film 1] Two sheets of the optical film 1 prepared by the above procedure were prepared and bonded together using a commercially available pressure-sensitive adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) so that the protective layers B1 faced each other, thereby preparing a laminated optical film 1 including a light absorption anisotropic layer.

[0115] The azimuth angle and polar angle of the central axis of transmittance of the laminated optical film 1 were examined by the following procedure. Using an AxoScan OPMF-2 (manufactured by Axometrics), the transmittance was measured while changing the azimuth angle and polar angle at which light was incident on the laminated optical film 1, as described above, to determine the direction of the central axis of transmittance of the laminated optical film 1. The angle between the central axis of transmittance of the laminated optical film 1 (lightly absorptive anisotropic layer) and the normal to the laminated optical film was 0°.

[0116] [Preparation of Optical Compensation Layer 1] (Extrusion Molding) A cycloolefin resin, ARTON G7810 (manufactured by JSR Corporation), was dried at 100° C. for 2 hours or more and melt-extruded using a twin-screw kneading extruder at 280° C. At this time, a screen filter, a gear pump, and a leaf disc filter were arranged in this order between the extruder and the die, and these were connected by melt piping. The resin was extruded through a T-die with a width of 1000 mm and a lip gap of 1 mm, and cast onto three consecutive casting rolls set at 180° C., 175° C., and 170° C. to obtain an unstretched film 1 with a width of 900 mm and a thickness of 94 μm.

[0117] (Stretching and Heat Fixing) The unstretched film 1 being transported was subjected to a stretching step and a heat fixation step by the following methods.

[0118] (a) Longitudinal Stretching Unstretched Film 1 was longitudinally stretched using a roll-to-roll longitudinal stretching machine with an aspect ratio (L / W) of 0.2 while being transported under the following conditions. -Conditions- Preheating temperature: 170°C Stretching temperature: 170°C Stretching ratio: 230% (b) Transverse Stretching The longitudinally stretched film was transversely stretched using a tenter while being transported under the following conditions. -Conditions- Preheating temperature: 170°C Stretching temperature: 170°C Stretching ratio: 10%

[0119] (c) Heat Setting Following the stretching step, the stretched film was heat-treated and heat-set under the following conditions while holding both ends of the stretched film by holding the ends with tenter clips so that the width was constant (within a range of expansion or contraction of 3%): Heat setting temperature: 165°C, Heat setting time: 30 seconds. The preheating temperature, stretching temperature, and heat setting temperature were average values ​​measured at five points in the width direction using a radiation thermometer.

[0120] (Winding) After heat setting, both ends were trimmed and the film was wound up under a tension of 25 kg / m to obtain a film roll of a stretched film having a width of 1340 mm and a wound length of 2000 m. The obtained stretched film had an Re of 150 nm, an Rth of 150 nm, and an Nz factor of 1.5. The stretched film obtained by the above procedure was designated as optical compensation layer 1.

[0121] [Preparation of Polarizing Plate] A polarizing plate having a polarizer thickness of 8 μm and one surface of the polarizer (other optically absorptive anisotropic layer) exposed was prepared in the same manner as in the preparation of polarizing plate 02 with a one-side protective film described in WO 2015 / 166991.

[0122] [Preparation of IPS Liquid Crystal Cell 1] An IPS liquid crystal cell having a liquid crystal layer between two glass substrates was prepared. To form the liquid crystal cell, a photo-alignment treatment was performed on the glass substrates with reference to Example 11 of JP 2005-351924 A to form an alignment layer, and a liquid crystal layer in which the liquid crystal compound was aligned was formed within the liquid crystal cell. The tilt angle of the liquid crystal compound with respect to the substrate surface was 0.1°. The Δn of the liquid crystal compound in the liquid crystal layer was 0.08625 at a wavelength of 550 nm, and Δnd was adjusted by adjusting the distance (gap; d) between the substrates. The in-plane retardation of Liquid Crystal Cell 1 was 275 nm (λ / 2). Using the above procedure, IPS Liquid Crystal Cell 1, an IPS-mode liquid crystal cell, was obtained.

[0123] [Preparation of Viewing Angle Control System 1] The prepared optical compensation layer 1 was bonded to one surface of the prepared IPS liquid crystal cell 1 using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). Next, the prepared polarizing plate was bonded to the polarizer surface using a commercially available adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.) so that the polarizer surface faced the surface of the optical compensation layer 1 opposite the IPS liquid crystal cell 1 side. At this time, the orientation relationship during bonding was adjusted so that the absorption axis of the polarizing plate and the slow axis of the optical compensation layer 1 were parallel. Next, the prepared laminated optical film 1 was bonded to the surface of the IPS liquid crystal cell opposite the surface to which the polarizing plate was bonded using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), thereby obtaining a viewing angle control system 1. During the above bonding, the liquid crystal layer in the IPS liquid crystal cell 1 was set so that the angle between the in-plane slow axis of the liquid crystal layer and the absorption axis of the polarizer when a voltage was applied was 45°, and the angle between the in-plane slow axis of the liquid crystal layer and the absorption axis of the polarizer when no voltage was applied was 0°.

[0124] [Fabrication of Image Display Device A1] Cosmoshine Super Birefringent Type (SRF, registered trademark, manufactured by Toyobo Co., Ltd.) (depolarizing film) was attached to the display screen of a Dynabook (registered trademark, manufactured by Toshiba Corporation), a notebook computer equipped with a liquid crystal display device, using a commercially available adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.). The viewing angle control system 1 prepared above was then placed on the depolarizing film to fabricate an image display device A1 with a viewing angle control function. In the fabricated image display device A1, the angle between the in-plane slow axis of the liquid crystal layer in the IPS liquid crystal cell 1 and the absorption axis of the polarizer could be switched between 45° and 0° by turning on and off the voltage applied to the IPS liquid crystal cell 1. When the vertical direction of the image display area of ​​the above-mentioned notebook computer is set to an azimuth angle of 0°, it was confirmed that when the image display device A1 was viewed from an oblique direction at azimuth angles of 90° and 270°, it was possible to switch between light-blocking mode and transmissive mode by turning the voltage applied to the IPS liquid crystal cell 1 on and off.

[0125] Example 2 Preparation of Optical Compensation Layer 2 In the preparation of optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 200 nm, an Rth of 100 nm, and an Nz factor of 1.0. This stretched film was designated as optical compensation layer 2.

[0126] [Fabrication of Image Display Device A2] An image display device A2 was fabricated in the same manner as in Example 1, except that in fabricating the viewing angle control system 1 of Example 1, the optical compensation layer 1 was changed to the optical compensation layer 2 described above.

[0127] Example 3 Preparation of Optical Compensation Layer 3 In the preparation of optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 65 nm, an Rth of 420 nm, and an Nz factor of 7.0. This stretched film was designated as optical compensation layer 3.

[0128] [Preparation of Viewing Angle Control System 3] The prepared optical compensation layer 3 was bonded to one surface of the IPS liquid crystal cell 1 prepared in Example 1 using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). Next, the laminated optical film 1 including the light absorption anisotropic layer prepared in Example 1 was bonded to the surface of the bonded optical compensation layer 3 opposite to the IPS liquid crystal cell 1 side using a commercially available adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.). Next, the polarizing plate prepared in Example 1 was bonded to the surface of the IPS liquid crystal cell 1 opposite to the surface to which the optical compensation layer 3 was bonded using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), thereby preparing a viewing angle control system 3. At this time, the polarizing plate was bonded so that the absorption axis of the polarizing plate and the slow axis of the optical compensation layer 3 were parallel to each other. During the above bonding, the liquid crystal layer in the IPS liquid crystal cell 1 was set so that the angle between the in-plane slow axis of the liquid crystal layer and the absorption axis of the polarizer when a voltage was applied was 45°, and the angle between the in-plane slow axis of the liquid crystal layer and the absorption axis of the polarizer when no voltage was applied was 0°.

[0129] [Fabrication of Image Display Device A3] Image display device A3 was fabricated in the same manner as in Example 1, except that viewing angle control system 1 in Example 1 was changed to viewing angle control system 3 described above.

[0130] Example 4 Preparation of Optical Compensation Layer 4 In the preparation of the optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 120 nm, an Rth of 420 nm, and an Nz factor of 4.0. This stretched film was designated as the optical compensation layer 4.

[0131] [Fabrication of Image Display Device A4] Image display device A4 was fabricated in the same manner as in Example 3, except that in fabricating viewing angle control system 3 of Example 3, optical compensation layer 3 was changed to optical compensation layer 4 described above.

[0132] Comparative Example 1 [Fabrication of Image Display Device B1] Image display device B1 was fabricated in the same manner as image display device A1 in Example 1, except that optical compensation layer 1 was not attached.

[0133] Example 5 Preparation of Optical Compensation Layer 5 In the preparation of optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 50 nm, an Rth of 100 nm, and an Nz factor of 2.5. This stretched film was designated as optical compensation layer 5.

[0134] [Preparation of IPS Liquid Crystal Cell 5] IPS liquid crystal cell 5 was prepared in the same manner as in Example 1, except that in the preparation of IPS liquid crystal cell 1 in Example 1, the distance between the substrates (gap; d) was adjusted so that the in-plane retardation of the liquid crystal layer was 140 nm (λ / 4).

[0135] [Fabrication of Image Display Device A5] An image display device A5 was fabricated in the same manner as in Example 1, except that in the fabrication of viewing angle control system 1 of Example 1, optical compensation layer 1 was replaced with the above-fabricated optical compensation layer 5 and IPS liquid crystal cell 1 was replaced with the above-fabricated IPS liquid crystal cell 5. In the fabricated image display device A5, the angle formed between the in-plane slow axis of the liquid crystal layer in IPS liquid crystal cell 5 and the absorption axis of the polarizer could be switched between 45° and 0° by turning on and off the voltage applied to IPS liquid crystal cell 5. When the up and down direction of the image display region of the notebook computer was defined as an azimuth angle of 0°, it was confirmed that the light-blocking mode and the transmissive mode could be switched by turning on and off the voltage applied to IPS liquid crystal cell 5.

[0136] Example 6 Preparation of Optical Compensation Layer 6 The following composition for forming the optical compensation layer 6 was prepared, and a uniform solution was obtained. Composition for Forming Optical Compensation Layer 6 Discotic liquid crystal compound CA-1 80 parts by mass Discotic liquid crystal compound CA-2 20 parts by mass Discotic liquid crystal compound CB-1 5.6 parts by mass Polymerizable monomer CS1 5.6 parts by mass Polymer CC-1 0.2 parts by mass Polymerization initiator (Irgacure 907, manufactured by BASF) 3 parts by mass Toluene 170 parts by mass Methyl ethyl ketone 73 parts by mass

[0137] Discotic Liquid Crystal Compound CA-1 (1,3,5-Substituted Benzene-Type Polymerizable Discotic Liquid Crystal Compound)

[0138] Discotic Liquid Crystal Compound CA-2 (1,3,5-Substituted Benzene-Type Polymerizable Discotic Liquid Crystal Compound)

[0139] Discotic liquid crystal compound CB-1 (polymerizable triphenylene-type discotic liquid crystal compound)

[0140] Polymerizable monomer CS1

[0141] Polymer CC-1 (hereinafter, copolymerization ratios in chemical structural formulas are shown in mass %)

[0142] A commercially available cellulose triacetate film (Fujitac ZRD40, manufactured by Fujifilm Corporation) was used as the support after being subjected to a saponification treatment. The composition for forming the optical compensation layer 6 was applied to the surface of the support, and the solvent was dried by a process of continuously heating from room temperature to 100°C. The coating film was then further heated for approximately 90 seconds in a drying zone at 100°C. After that, the temperature was lowered to 60°C, and the coating film was then dried under atmospheric pressure at 300 mJ / cm. ２ The coating film was cured by UV exposure to form a cured film. After allowing the cured film to cool to room temperature, the orientation state of the cured film was observed, and it was found that the discotic liquid crystal compound was horizontally aligned without any defects. The resulting laminate film of the cured film and the support had an Re of 3 nm, an Rth of 200 nm, and an Nz factor of 67.2. The above laminate film was used as optical compensation layer 6.

[0143] [Fabrication of Image Display Device A6] An image display device A6 was fabricated in the same manner as in Example 5, except that in fabricating the viewing angle control system 5 of Example 5, the optical compensation layer 5 was changed to the optical compensation layer 6 described above.

[0144] Example 7 Preparation of Optical Compensation Layer 7 In the preparation of the optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 75 nm, an Rth of 150 nm, and an Nz factor of 2.5. This stretched film was designated as the optical compensation layer 7.

[0145] [Preparation of IPS Liquid Crystal Cell 7] IPS liquid crystal cell 7 was prepared in the same manner as in Example 1, except that in the preparation of IPS liquid crystal cell 1 in Example 1, the distance between the substrates (gap; d) was adjusted so that the in-plane retardation of the liquid crystal layer was 400 nm.

[0146] [Fabrication of image display device A7] Image display device A7 was fabricated in the same manner as in Example 5, except that in the fabrication of viewing angle control system 5 in Example 5, optical compensation layer 5 was changed to the above-mentioned optical compensation layer 7, and IPS liquid crystal cell 5 was changed to the above-mentioned IPS liquid crystal cell 7.

[0147] Example 8 Preparation of Optical Compensation Layer 8 A 40 μm-thick cellulose acylate film (TAC substrate; manufactured by Fujifilm Corporation, TG40) was subjected to a saponification treatment, and a composition for forming the optical compensation layer 8 prepared according to the table below was applied with a wire bar to form a coating film. The coating film was heated with warm air at 40° C. for 60 seconds to dry the solvent of the composition and to ripen the liquid crystal compound into an aligned state. Subsequently, the film was irradiated with ultraviolet light (300 mJ / cm ) at 40° C. in a nitrogen-purged atmosphere (oxygen concentration 100 ppm). ２ ) was performed to fix the alignment of the liquid crystalline compound, thereby obtaining a cured film. The obtained laminated film of the cured film and the support had an Re of 4 nm, an Rth of −300 nm, and an Nz factor of −74.5. The above laminated film was used as optical compensation layer 8.

[0148] -------------------------------- Composition for forming optical compensation layer 8 -------------------------------------------------- Rod-shaped liquid crystal compound-1 described below: 83 parts by mass Rod-shaped liquid crystal compound-2 described below: 15 parts by mass Rod-shaped liquid crystal compound-3 described below: 2 parts by mass Polymerizable monomer (M-1) described below: 8 parts by mass Polymerization initiator (Irgacure 127, manufactured by BASF) 2 parts by mass Polymerization initiator (Irgacure OXE01, manufactured by BASF) 4 parts by mass Surfactant F-1 described below: 0.18 parts by mass Surfactant F-2 described below: 0.24 parts by mass Onium compound S01 described below: 2 parts by mass Polymer compound A-1 described below: 5 parts by mass Toluene 621 parts by mass Methyl ethyl ketone 69 parts by mass ----------------------------------------------------------------------------------

[0149] Rod-shaped liquid crystal compound-1

[0150] Rod-shaped liquid crystal compound-2

[0151] Rod-shaped liquid crystal compound-3

[0152] Polymerizable Monomer (M-1)

[0153] Surfactant F-1

[0154] Surfactant F-2

[0155] Onium Compound S01

[0156] Polymer compound A-1

[0157] [Fabrication of Image Display Device A8] Image display device A8 was fabricated in the same manner as in Example 7, except that in fabricating viewing angle control system 7 of Example 7, optical compensation layer 7 was changed to optical compensation layer 8 described above.

[0158] Example 9 Preparation of Optical Compensation Layer 9 In the preparation of optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 75 nm, an Rth of 500 nm, and an Nz factor of 7.2. This stretched film was designated optical compensation layer 9.

[0159] [Preparation of IPS Liquid Crystal Cell 9] IPS liquid crystal cell 9 was prepared in the same manner as in Example 1, except that in the preparation of IPS liquid crystal cell 1 of Example 1, the angle between the in-plane slow axis of the liquid crystal layer when the voltage was ON and the in-plane slow axis when the voltage was OFF was set to 60°.

[0160] [Fabrication of Image Display Device A9] Image display device A9 was fabricated in the same manner as in Example 3, except that in the fabrication of image display device A3 of Example 3, IPS liquid crystal cell 1 was replaced with the above-described IPS liquid crystal cell 9, and optical compensation layer 3 was replaced with the above-described optical compensation layer 9. In the fabricated image display device A9, the angle between the in-plane slow axis of the liquid crystal layer in the IPS liquid crystal cell and the absorption axis of the polarizer could be switched between 60° and 0° by turning on and off the voltage applied to the IPS liquid crystal cell 9. When the up-down direction of the image display region of the notebook computer was defined as an azimuth angle of 0°, the image display device A9 was viewed obliquely at azimuth angles of 90° and 270°, and it was confirmed that the light-blocking mode and the transmissive mode could be switched by turning on and off the voltage applied to the IPS liquid crystal cell 9.

[0161] Example 10 [Preparation of Optical Compensation Layer 10] A stretched film having an Re of 120 nm, an Rth of 420 nm, and an Nz factor of 4.0 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was designated as the optical compensation layer 10.

[0162] [Fabrication of Image Display Device A10] An image display device A10 was fabricated in the same manner as in Example 9, except that in fabricating the viewing angle control system 9 of Example 9, the optical compensation layer 9 was changed to the optical compensation layer 10 described above.

[0163] Example 11 [Preparation of Optical Compensation Layer 11] A stretched film having an Re of 200 nm, an Rth of 180 nm, and an Nz factor of 1.4 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was designated as the optical compensation layer 11.

[0164] [Preparation of IPS Liquid Crystal Cell 11] IPS liquid crystal cell 11 was prepared in the same manner as in Example 1, except that in the preparation of IPS liquid crystal cell 1 of Example 1, the angle between the in-plane slow axis of the liquid crystal layer when the voltage was ON and the in-plane slow axis when the voltage was OFF was 25°.

[0165] [Fabrication of Image Display Device A11] An image display device A11 was fabricated in the same manner as in Example 5, except that in the fabrication of the image display device A5 of Example 5, the IPS liquid crystal cell 5 was replaced with the above-described IPS liquid crystal cell 11, the optical compensation layer 5 was replaced with the above-described optical compensation layer 11, and the layers were laminated so that the absorption axis of the polarizer and the slow axis of the optical compensation layer 11 were perpendicular to each other. For the fabricated image display device A11, the angle between the in-plane slow axis of the liquid crystal layer in the IPS liquid crystal cell and the absorption axis of the polarizer could be switched between 65° and 90° by turning on and off the voltage applied to the IPS liquid crystal cell. When the up-down direction of the image display region of the notebook computer was defined as an azimuth angle of 0°, the image display device A11 was viewed obliquely at azimuth angles of 90° and 270°, and it was confirmed that the light-blocking mode and the transmission mode could be switched by turning on and off the voltage applied to the IPS liquid crystal cell 11.

[0166] Example 12 [Preparation of Optical Compensation Layer 12] A stretched film having an Re of 150 nm, an Rth of 500 nm, and an Nz factor of 3.8 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was designated as the optical compensation layer 12.

[0167] [Fabrication of IPS Liquid Crystal Cell 12] IPS liquid crystal cell 12 was fabricated in the same manner as in Example 1, except that in the fabrication of IPS liquid crystal cell 1 of Example 1, the distance between the substrates (gap; d) was adjusted so that the in-plane retardation of the liquid crystal layer was 350 nm, and the angle between the in-plane slow axis of the liquid crystal layer when the voltage was ON and the in-plane slow axis when the voltage was OFF was 65°.

[0168] [Fabrication of Image Display Device A12] Image display device A12 was fabricated in the same manner as in Example 5, except that in the fabrication of image display device A5 of Example 5, the IPS liquid crystal cell 5 was replaced with the IPS liquid crystal cell 12, and the optical compensation layer 5 was replaced with the optical compensation layer 12. In the fabricated image display device A12, the angle between the in-plane slow axis of the liquid crystal layer in the IPS liquid crystal cell and the absorption axis of the polarizer could be switched between 65° and 0° by turning on and off the voltage applied to the IPS liquid crystal cell. When the up-down direction of the image display region of the notebook computer was defined as an azimuth angle of 0°, the image display device A12 was viewed from an oblique direction at azimuth angles of 90° and 270°, and it was confirmed that the light-blocking mode and the transmissive mode could be switched by turning on and off the voltage applied to the IPS liquid crystal cell 12.

[0169] Example 13 [Preparation of Optical Compensation Layer 13] A stretched film having an Re of 150 nm, an Rth of 300 nm, and an Nz factor of 2.5 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was used as the optical compensation layer 13.

[0170] [Fabrication of Image Display Device A13] An image display device A13 was fabricated in the same manner as in Example 12, except that in the fabrication of the viewing angle control system 12 of Example 12, the optical compensation layer 12 was changed to the optical compensation layer 13 described above.

[0171] Example 14 Preparation of Optical Compensation Layer 14 A stretched film having an Re of 200 nm, an Rth of 300 nm, and an Nz factor of 2.0 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was used as the optical compensation layer 14.

[0172] [Fabrication of Image Display Device A14] An image display device A14 was fabricated in the same manner as in Example 12, except that in the fabrication of the viewing angle control system 12 of Example 12, the optical compensation layer 12 was changed to the above-described optical compensation layer 14.

[0173] Comparative Example 2 [Preparation of Image Display Device B2] Image display device B2 was prepared in the same manner as image display device A5 in Example 5, except that optical compensation layer 5 was not attached.

[0174] Example 15 Preparation of Optical Compensation Layer 15 A stretched film having an Re of 200 nm, an Rth of 400 nm, and an Nz factor of 2.5 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of Optical Compensation Layer 1 in Example 1. This stretched film was designated Optical Compensation Layer 15.

[0175] [Fabrication of VA Liquid Crystal Cell 13] A glass substrate with electrodes was immersed in a solution of household neutral detergent diluted with 50 cc of water for 30 seconds and allowed to air dry. A liquid crystal alignment film (JALS-2021-R1, manufactured by JSR Corporation) was formed on a separately cleaned glass substrate, and the formed alignment film was then rubbed. The glass substrate with electrodes and the glass substrate with the alignment film were assembled with the rubbed surface facing inward to form a liquid crystal cell. The liquid crystal cell was fabricated by dropping and sealing a liquid crystal material with negative dielectric anisotropy (MLC6608, manufactured by Merck) between the substrates, forming a vertically aligned liquid crystal layer between the substrates. The cell gap between the substrates was adjusted to achieve a Δnd of 275 nm at a wavelength of 550 nm. This procedure yielded VA liquid crystal cell 13, a VA-mode liquid crystal cell. In the VA liquid crystal cell 13, the alignment direction of the liquid crystal material (liquid crystal compound) changes from vertical alignment to horizontal alignment when a voltage is applied.

[0176] [Fabrication of Image Display Device A15] Image display device A15 was fabricated in the same manner as in Example 1, except that in the fabrication of image display device A1 in Example 1, IPS liquid crystal cell 1 was changed to the above-described VA liquid crystal cell 13, optical compensation layer 1 was changed to the above-described optical compensation layer 15, and the polarizing plate and the optical compensation layer 15 were attached so that their absorption axes were parallel to each other. The polarizing plate and the VA liquid crystal cell 13 were attached so that the angle between the alignment direction of the liquid crystal in the state where a voltage was applied to the VA liquid crystal cell 13 and the absorption axis of the polarizing plate formed a 45° angle. It was confirmed that the fabricated image display device A15 was able to change the alignment direction of the liquid crystal compound by turning on and off the voltage (20 V) applied to the VA liquid crystal cell 13, thereby enabling switching between a light-blocking mode (ON) and a transmission mode (OFF).

[0177] Example 16 [Preparation of Optical Compensation Layer 16] A stretched film having an Re of 200 nm, an Rth of 600 nm, and an Nz factor of 3.5 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was designated as the optical compensation layer 16.

[0178] [Fabrication of Image Display Device A16] Image display device A16 was fabricated in the same manner as in Example 1, except that in fabricating image display device A3 of Example 3, IPS liquid crystal cell 1 was replaced with the above-described VA liquid crystal cell 13, optical compensation layer 3 was replaced with the above-described optical compensation layer 16, and the layers were laminated so that the absorption axis of the polarizing plate and the slow axis of the optical compensation layer 16 were perpendicular to each other. The layers were laminated so that the angle between the alignment direction of the liquid crystal in a state where a voltage was applied to the VA liquid crystal cell 13 and the absorption axis of the polarizing plate was 45°. It was confirmed that the fabricated image display device A16 was able to change the alignment direction of the liquid crystal compound by turning on (20 V) and off the voltage applied to the VA liquid crystal cell 13, thereby enabling switching between a light-blocking mode (ON) and a transmission mode (OFF).

[0179] Example 17 Preparation of Optical Compensation Layer 17-1 (Formation of Alignment Film 2) The following composition for forming an alignment film 2 was continuously applied to one side of a 40 μm-thick cellulose acylate film (TAC substrate; manufactured by Fujifilm Corporation, TG40) using a #14 wire bar. The film was dried with hot air at 60° C. for 60 seconds and then with hot air at 100° C. for 120 seconds.

[0180] -------------------------------------------------- Composition of composition 2 for forming alignment film ------------------------------------------------------------------ Modified polyvinyl alcohol PVA-1 described above: 10 parts by mass Water: 308 parts by mass Methanol: 70 parts by mass Isopropanol: 29 parts by mass Photopolymerization initiator (Irgacure 2959, manufactured by BASF): 0.8 parts by mass

[0181] (Formation of Retardation Layer A) The prepared alignment film 2 was continuously subjected to rubbing treatment. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film and the rotation axis of the rubbing roller was 90° (the film width direction was 0°, the film longitudinal direction was 90°, and when observed from the alignment film side, the clockwise direction with the film width direction as the reference is represented as a positive value, so the rotation axis of the rubbing roller was 0°).

[0182] A retardation layer coating solution A containing a discotic liquid crystal compound of the following composition was continuously applied to the above-prepared alignment film 2 using a wire bar to prepare a retardation layer A. To dry the solvent in the coating solution and ripen the alignment of the discotic liquid crystal compound, the film was heated with hot air at 130°C for 90 seconds, followed by hot air at 100°C for 60 seconds, and then irradiated with UV at 80°C to fix the alignment of the liquid crystal compound. The thickness of the retardation layer A was 1.0 μm, and the Re at 550 nm was 125 nm. The average tilt angle of the discotic liquid crystal compound's disc surface with respect to the film surface was 90°, confirming that the discotic liquid crystal compound was aligned perpendicular to the film surface. Furthermore, the angle of the slow axis of the retardation layer A was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was 0° (the longitudinal direction was 90°), the slow axis was 0° when viewed from the retardation layer A side.

[0183] -------------------------------- Composition of retardation layer coating solution A------------------------------------------------ 80 parts by mass of discotic liquid crystal-1 below 20 parts by mass of discotic liquid crystal-2 below 0.55 parts by mass of alignment film interface aligning agent-1 below 0.05 parts by mass of alignment film interface aligning agent-2 below 0.20 parts by mass of surfactant F-4 below 10 parts by mass of modified trimethylolpropane triacrylate 3.0 parts by mass of photopolymerization initiator (Irgacure 907, manufactured by BASF) 200 parts by mass of methyl ethyl ketone------------------------------------------------

[0184] Discotic Liquid Crystal-1

[0185] Discotic Liquid Crystal-2

[0186] Alignment film interface alignment agent-1

[0187] Alignment film interface alignment agent-2

[0188] Surfactant F-4

[0189] [Preparation of Optical Compensation Layer 17-2] Optical compensation layer 17-2 was prepared in the same manner as in Example 8, except that in the preparation of optical compensation layer 8 in Example 8, the composition for forming optical compensation layer 8 was changed to the composition for forming optical compensation layer 17-2 described below, and the coating film thickness was adjusted so that Rth was −90 nm.

[0190] -------------------------------- Composition for forming optical compensation layer 17-2------------------------------------------------ Rod-shaped liquid crystal compound-1 83 parts by mass Rod-shaped liquid crystal compound-2 15 parts by mass Rod-shaped liquid crystal compound-3 2 parts by mass Polymerizable monomer (M-1) 8 parts by mass Polymerization initiator (Irgacure 127, manufactured by BASF) 2 parts by mass Polymerization initiator (Irgacure OXE01, manufactured by BASF) 4 parts by mass Surfactant F-1 0.62 parts by mass Surfactant F-2 0.82 parts by mass Onium compound S01 2 parts by mass Polymer compound A-1 5 parts by mass Toluene 621 parts by mass Methyl ethyl ketone 69 parts by mass ----------------------------------------------------------------------------------

[0191] [Preparation of Optical Compensation Layer 17] Optical compensation layer 17-1 and optical compensation layer 17-2 prepared by the above procedure were prepared and bonded together using a commercially available pressure-sensitive adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) so that the coating layers faced each other, to prepare optical compensation layer 17. The prepared optical compensation layer 17 had an Re of 125 nm, an Rth of −150 nm, and an Nz factor of −0.7.

[0192] [Fabrication of Image Display Device A17] Image display device A17 was fabricated in the same manner as in Example 16, except that in the fabrication of image display device A16 of Example 16, optical compensation layer 16 was changed to the above-described optical compensation layer 17, the optical compensation layer 17-1 layer included in optical compensation layer 17 was disposed on the light absorption anisotropic layer 1 side, and the layers were laminated so that the absorption axis of the polarizing plate and the slow axis of optical compensation layer 17 were perpendicular to each other. It was confirmed that the fabricated image display device A17 changed the alignment direction of the liquid crystal compound by turning on (20 V) and off the voltage applied to VA liquid crystal cell 13, and was therefore capable of switching between a light-blocking mode (ON) and a transmission mode (OFF).

[0193] Example 18 [Preparation of ECB Liquid Crystal Cell 14] A polyimide film was provided as an alignment film on a glass substrate with an ITO electrode, and the alignment film was subjected to a rubbing treatment. The two resulting glass substrates were bonded together, facing each other with the rubbing directions parallel to each other. A liquid crystal material (MLC-9100 manufactured by Merck) with positive dielectric anisotropy was injected dropwise between the upper and lower substrates and sealed therein to prepare a liquid crystal cell. During this process, the cell gap between the substrates was adjusted so that Δnd at a wavelength of 550 nm was 275 nm. Using the above procedure, ECB liquid crystal cell 14, an ECB-type liquid crystal cell, was obtained.

[0194] [Fabrication of Image Display Device A18] Image display device A18 was fabricated in the same manner as in Example 17, except that in the fabrication of image display device A17 of Example 17, liquid crystal cell 13 was changed to liquid crystal cell 14. It was confirmed that the fabricated image display device A18 was capable of switching between a light-shielding mode (OFF) and a transmission mode (ON) by changing the alignment direction of the liquid crystal compound by turning on (10 V) and off the voltage applied to the ECB liquid crystal cell.

[0195] Comparative Example 3 [Fabrication of Image Display Device B3] Image display device B3 was fabricated in the same manner as image display device A15 in Example 15, except that the optical compensation layer 15 was not attached.

[0196] Comparative Example 4 [Fabrication of Image Display Device B4] Image display device B4 was fabricated in the same manner as image display device A18 in Example 18, except that the optical compensation layer 17 was not attached.

[0197] Example 19 Preparation of Optical Compensation Layer 19 In the preparation of optical compensation layer 1 in Example 1, the film thickness, stretching temperature, and stretching ratio were adjusted to obtain a stretched film having an Re of 150 nm, an Rth of 300 nm, and an Nz factor of 2.5. This stretched film was designated optical compensation layer 19.

[0198] [Preparation of Multi-Domain Alignment Film] A commercially available polyimide alignment film (SE-150 manufactured by Nissan Chemical Industries, Ltd.) was coated on a glass substrate with electrodes and heated at 250° C. for 1 hour. This alignment film was divided into two regions by mask rubbing treatment, and a multi-domain alignment film was prepared in which the rubbing axis was oriented at 90° in region 1 and 270° in region 2.

[0199] [Preparation of Multi-Domain Substrate] A coating solution was prepared by dissolving 100 parts by mass of the following discotic liquid crystal compound 1, 0.8 parts by mass of the following polymer compound 2, parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by Ciba-Geigy), and parts by mass of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) in 200 parts by mass of methyl ethyl ketone. This coating solution was spin-coated onto the surface of the above-mentioned multi-domain alignment film. This was heated in a constant temperature zone at 120°C for 2 minutes to align the discotic liquid crystal compound. Next, in an atmosphere of 70°C, 120 W / cm ２ The substrate was irradiated with UV light for 1 minute using a high-pressure mercury lamp under the conditions of 1.0 to 1.5, thereby polymerizing the discotic liquid crystal compound and fixing the alignment state. The substrate was then allowed to cool to room temperature. Thus, a multi-domain substrate was fabricated. Observation of the multi-domain substrate with a polarizing microscope confirmed that the discotic liquid crystal compound was aligned in each domain along the respective rubbing directions.

[0200] Discotic liquid crystal compound 1

[0201] High molecular compound 2

[0202] [Preparation of VA Liquid Crystal Cell 15] VA Liquid Crystal Cell 15 was prepared in the same manner as in Example 15, except that in the preparation of VA Liquid Crystal Cell 13 of Example 15, the substrate was the multi-domain substrate prepared above, and the distance between the substrates (gap; d) was adjusted so that the Δnd of the liquid crystal layer was 700 nm.

[0203] [Fabrication of Image Display Device A19] Image display device A19 was fabricated in the same manner as in Example 15, except that in the fabrication of image display device A15 of Example 15, liquid crystal cell 13 was changed to liquid crystal cell 15, optical compensation layer 15 was changed to the above-mentioned optical compensation layer 19, and the polarizing plate and the optical compensation layer 19 were laminated so that their absorption axes were parallel to each other. In this case, the polarizing plate and the liquid crystal cell were laminated so that the alignment direction of the liquid crystal in a state where a voltage of 20 V was applied to the VA liquid crystal cell 15 was parallel to the absorption axis of the polarizing plate. It was confirmed that the alignment direction of the liquid crystal compound in the fabricated image display device A19 changed when the voltage applied to the VA liquid crystal cell 15 was turned ON (2.4 V) and OFF, enabling switching between a light-blocking mode (OFF) and a transmission mode (ON).

[0204] Example 20 Preparation of Optical Compensation Layer 20-1 Optical compensation layer 20-1 was prepared in the same manner as in Example 17, except that in the preparation of optical compensation layer 17-1 in Example 17, the coating film thickness was adjusted so that Re was 150 nm and Rth was −75 nm.

[0205] [Preparation of Optical Compensation Layer 20] The optical compensation layer 20-1 and the optical compensation layer 8 prepared by the above procedure were prepared and bonded together using a commercially available pressure-sensitive adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) so that the coating layers faced each other, to prepare the optical compensation layer 20. The prepared optical compensation layer 17 had an Re of 150 nm, an Rth of −375 nm, and an Nz factor of −2.0.

[0206] [Fabrication of Image Display Device A20] Image display device A20 was fabricated in the same manner as in Example 19, except that in the fabrication of image display device A19 of Example 19, optical compensation layer 19 was changed to the above-described optical compensation layer 120, the optical compensation layer 20-1 layer included in optical compensation layer 20 was disposed on the liquid crystal cell 15 side, and the optical compensation layer 17 was attached so that the absorption axis of the polarizing plate and the slow axis of optical compensation layer 17 were perpendicular to each other. It was confirmed that the fabricated image display device A20 changed the alignment direction of the liquid crystal compound by turning on (2.4 V) and off the voltage applied to VA liquid crystal cell 15, and was therefore capable of switching between a light-blocking mode (OFF) and a transmission mode (ON).

[0207] Example 21 [Preparation of Optical Compensation Layer 21] A stretched film having an Re of 75 nm, an Rth of 125 nm, and an Nz factor of 2.2 was obtained by adjusting the film thickness, stretching temperature, and stretching ratio in the preparation of the optical compensation layer 1 in Example 1. This stretched film was designated as the optical compensation layer 21.

[0208] [Fabrication of Image Display Device A21] Image display device A21 was fabricated in the same manner as in Example 16, except that in the fabrication of image display device A16 of Example 16, optical compensation layer 16 was changed to the above-described optical compensation layer 21, liquid crystal cell 13 was changed to liquid crystal cell 15, and the polarizing plate and the slow axis of optical compensation layer 17 were attached so that they were perpendicular to each other. It was confirmed that the fabricated image display device A21 changed the alignment direction of the liquid crystal compound by turning on (2.4 V) and off the voltage applied to VA liquid crystal cell 15, and was therefore capable of switching between a light-blocking mode (OFF) and a transmission mode (ON).

[0209] Comparative Example 5 [Preparation of Image Display Device B5] Image display device B5 was prepared in the same manner as image display device A19 in Example 19, except that the optical compensation layer 19 was not attached.

[0210] <Evaluation of Viewing Angle Control System> [Evaluation of Visibility in the Left-Right Direction] The light-blocking properties and transmittance properties of the image display devices of Examples 1 to 21 and Comparative Examples 1 to 5 were evaluated using the following procedure. That is, for each of the image display devices, the visibility of the displayed image was evaluated in the light-blocking mode and the transmittance mode when viewed from an azimuth angle of 90° (rightward) and a polar angle of 45°, with the up-down direction of the image display area of ​​the notebook computer being defined as an azimuth angle of 0°. The visibility (light-blocking properties) in the light-blocking mode and the visibility (transmittance) in the transmittance mode were evaluated based on the following criteria. The results are shown in the table below. A similar evaluation was performed when viewed from an azimuth angle of 270° (leftward) and a polar angle of 45°, and the evaluation results were similar to those for the rightward direction.

[0211] (Visibility in light-blocking mode) A: The image cannot be recognized. B: The image is difficult to recognize. C: The image can be recognized to some extent. D: The image can be recognized. In practice, ratings A to C are preferable.

[0212] (Visibility in transmission mode) A: The image is recognizable and appears bright. B: The image is recognizable, but appears slightly dark. C: The image is dark and difficult to recognize. In practical terms, an A or B rating is preferable.

[0213] [Evaluation of Visibility in Other Directions] For the image display devices of Examples 5 to 14 and Comparative Example 2, the visibility of the displayed image was evaluated when observed not only from the left-right direction but also from the up-down direction (azimuth angles of 0° and 180°), the diagonally upper right direction (azimuth angle of 45°), the diagonally lower right direction (azimuth angle of 135°), the diagonally lower left direction (azimuth angle of 225°), and the diagonally upper left direction (azimuth angle of 315°). Specifically, when the left-right direction was in the transmissive mode in the above evaluation, the visibility of the displayed image (visibility in other directions) was evaluated according to the following criteria when the displayed image was observed from each of the above azimuth angles and a polar angle of 45°. The results are shown in the table below.

[0214] (Visibility from other directions in transmissive mode) A+: The image is bright and recognizable from any of the above directions. A: The image is recognizable from any of the above directions, but there are some directions in which it appears a little dark. B: The image is recognizable from any of the above directions, but it is dark overall. C: Of the above directions, there are some directions in which the image is dark and difficult to recognize.

[0215] <Results> The configurations of the image display devices of the examples and comparative examples and the evaluation results are shown in Tables 1 to 4. The "switching angle" column of the liquid crystal cell indicates the angle at which the in-plane slow axis of the liquid crystal cell can be set relative to the absorption axis direction of the polarizer in the polarizing plate.

[0216]

[0217]

[0218]

[0219]

[0220]

[0221] The results shown in Tables 1 to 4 show that the image display devices of the comparative examples not including an optical compensation layer were inferior in light blocking properties to the image display devices of the examples including an optical compensation layer.

[0222] 10a, 10b Viewing angle control system 12 Light absorption anisotropic layer 14 Liquid crystal cell 16 Polarizer 18 Optical compensation layer 20 Display panel 100a, 100b Image display device

Claims

1. A viewing angle control system comprising, in this order, an optically absorptive anisotropic layer, a liquid crystal cell, and a polarizer, wherein the angle between the central axis of transmittance of the optically absorptive anisotropic layer and a normal to the optically absorptive anisotropic layer is 0 to 45°, and an optical compensation layer is provided between the optically absorptive anisotropic layer and the liquid crystal cell and / or between the liquid crystal cell and the polarizer, and wherein no other optically absorptive anisotropic layer or other polarizer is provided between the optically absorptive anisotropic layer and the polarizer.

2. The viewing angle control system according to claim 1, wherein the liquid crystal cell is an in-plane switching type liquid crystal cell.

3. The viewing angle control system according to claim 1, wherein the liquid crystal cell is a vertical alignment type liquid crystal cell or an electric field controlled birefringence type liquid crystal cell.

4. The viewing angle control system according to any one of claims 1 to 3, wherein the optical compensation layer is disposed between the light absorption anisotropic layer and the liquid crystal cell.

5. An image display device comprising the viewing angle control system according to any one of claims 1 to 3.

Images