Optical member and ar glasses having optical member

Abstract

The present invention addresses the problem of providing an optical member and AR glasses using said optical member, wherein when the optical member is used in a head-mounted display through which the background is visible, such as AR glasses, the brightness of the background is excellent, and furthermore a visibility problem caused by external light which is incident from above the head of a user using the head-mounted display can be suppressed.　This optical member has: an optical film that has a polarization control layer and a light absorption anisotropic layer and exhibits prescribed optical characteristics; and a light guide plate that is positioned on the side of the optical film having the polarization control layer and is provided with a diffraction element in which the diffraction efficiency changes in accordance with the polarization direction, wherein the angle formed by the transmittance center axis of the light absorption anisotropic layer and the normal direction of the light absorption anisotropic layer is 0-45°, the polarization control layer is a λ / 4 film, and when the optical member has been positioned in a use mode, the angle formed by the slow axis of the λ / 4 film and the horizontal direction is 0-20°.

Description

Optical member and AR glasses having the optical member

[0001] The present invention relates to an optical element and AR glasses having the optical element.

[0002] In recent years, head-mounted displays such as augmented reality (AR) glasses that project an image superimposed on a background have appeared. The AR glasses have, for example, an image display element, a light guide plate, and a diffraction element. The image light emitted from the image display element is diffracted by the diffraction element, enters the light guide plate, is guided by the light guide plate, and the guided image light is diffracted by the diffraction element to display an image toward a viewer. Because the light guide plate is transparent, the AR glasses can project an image superimposed on a background.

[0003] Such AR glasses have the problem that external light incident from a specific oblique direction is diffracted toward the viewer while being color-separated by the diffraction element, and the color-separated external light is visible to the viewer, making it difficult to see the image displayed by the AR glasses, the outside scenery, etc. The angle of incidence (the oblique angle of incidence with respect to the main surface of the diffraction element) that is visible varies depending on the pitch of the diffraction element, but a particular problem occurs when external light that is incident at an angle between 40° and 80° with respect to the normal to the diffraction element is visible.

[0004] In response to this, some AR glasses use a so-called ND filter (Neutral Density filter) to reduce the transmittance of external light, thereby suppressing visibility problems caused by the incidence of external light.

[0005] International Publication No. 2023 / 112835

[0006] However, when an ND filter is used in a head-mounted display that allows the user to see the background, such as with AR glasses, the transmittance of the ND filter must be low in order to suppress visibility problems caused by the incidence of external light. Therefore, with AR glasses that use an ND filter, the transmittance of light incident from above as well as the transmittance of light incident from the front, i.e., the background, is reduced. As a result, while AR glasses that use an ND filter can suppress visibility problems caused by external light, the background may become dark, resulting in poor visibility of the background.

[0007] The object of the present invention is to solve these problems by providing an optical element that, when used in a head-mounted display in which the background can be seen, such as AR glasses, provides excellent background brightness and can also suppress visibility problems caused by external light entering from above the head of a user using the head-mounted display, and AR glasses that use this optical element.

[0008] The present inventors have found that the above problems can be solved by the following configuration.

[0009] [1] An optical element comprising: an optical film having a polarization control layer and a light-absorbing anisotropic layer; and a light guide plate disposed on the side of the optical film having the polarization control layer, the light guide plate having a diffraction element whose diffraction efficiency changes depending on the polarization direction, wherein the angle formed by the central axis of transmittance of the light-absorbing anisotropic layer and the normal direction of the light-absorbing anisotropic layer is 0 to 45°; the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film; the polarization control layer is a λ / 4 film; and when the optical element is arranged in a usage configuration, the angle formed by the slow axis of the λ / 4 film and the horizontal direction is 0 to 20°. [2] An optical element comprising: an optical film having a polarization control layer and a light-absorbing anisotropic layer; and a light guide plate disposed on the side of the optical film having the polarization control layer, and equipped with a diffraction element whose diffraction efficiency changes depending on the polarization direction, wherein the angle formed between the transmittance central axis of the light-absorbing anisotropic layer and the normal direction of the light-absorbing anisotropic layer is 0 to 45°; the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in any one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film; and the polarization control layer comprises a first λ / 4 film and a second λ / 4 film, and the angle formed between the slow axis of the first λ / 4 film and the slow axis of the second λ / 4 film is 30 to 60°. [3] The optical member according to [2], wherein the polarization control layer includes the first λ / 4 film, the second λ / 4 film, and a C plate.[4] An optical element comprising: an optical film having a polarization control layer and a light-absorbing anisotropic layer; and a light guide plate disposed on the side of the optical film having the polarization control layer, the light guide plate having a diffraction element whose diffraction efficiency changes depending on the polarization direction, wherein the angle between the transmittance central axis of the light-absorbing anisotropic layer and the normal direction of the light-absorbing anisotropic layer is 0 to 45°, the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in any one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film, and the polarization control layer is a layer containing one or more layers of a liquid crystal compound having a twist structure. [5] The optical element according to [4], wherein the polarization control layer has, in this order from the side where the diffraction element is disposed, a layer containing one or more layers of a liquid crystal compound having a twist structure and a C-plate. [6] AR glasses having the optical member according to any one of [1] to [5].

[0010] According to the present invention, an optical element can be provided that, when used in a head-mounted display that allows the background to be seen, such as AR glasses, provides excellent background brightness and also suppresses visibility problems caused by external light incident from above the user's head. Furthermore, according to the present invention, AR glasses using the optical element can also be provided.

[0011] 1A to 1C are side views conceptually showing an example of an image display device using a first optical member, a second optical member, and a third optical member, respectively.

[0012] The present invention will be described in detail below. 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.

[0013] In this specification, Re(λ) and Rth(λ) are the in-plane retardation (nm) and the thickness direction retardation (nm) at a wavelength λ, respectively. Re(λ) is measured using an Axometrics AxoScan by irradiating light with a wavelength λ nm in the normal direction of the film. Simply referring to Re and Rth indicates the value at λ = 550 nm. When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth(λ) is calculated by the following method. The measurement wavelength λ nm can be selected by manually changing the wavelength selection filter, or by converting the measured value using a program or the like. Rth(λ) is measured by measuring Re(λ) at seven points, with the in-plane slow axis as the tilt axis (rotation axis), by irradiating light with a wavelength of λ nm from each tilted direction in 10-degree increments from the normal direction to the film normal, and calculating Rth(λ) using AxoScan based on the measured retardation values, the assumed average refractive index, and the input film thickness value. In this case, the in-plane slow axis of the film is determined by AxoScan. If there is no in-plane slow axis of the film, any in-plane direction of the film is used as the rotation axis. In the above case, for a film having a direction in which the retardation value is zero at a certain tilt angle from the normal direction, with the in-plane slow axis as the rotation axis, the retardation value at a tilt angle greater than that tilt angle is calculated using AxoScan after changing its sign to negative. Incidentally, the retardation values ​​can be measured from two arbitrary tilted directions with the slow axis as the tilt axis (axis of rotation), and Rth can be calculated from the measured values, the assumed value of the average refractive index, and the input film thickness value using the following formulas (I) and (II). In this case, when there is no slow axis in the plane of the film, any direction in the plane of the film is taken as the axis of rotation.

[0014]

[0015] In the formula, Re(θ) represents the retardation value in a direction inclined at an angle θ from the normal direction, nx represents the refractive index in the in-plane slow axis direction, ny represents the refractive index in the in-plane direction perpendicular to nx, nz represents the refractive index in the direction perpendicular to nx and ny, and d represents the film thickness.

[0016] When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, i.e., when the film has no optic axis, Rth(λ) is calculated by the following method. Re(λ) is measured at 13 points by irradiating light of wavelength λ nm from each tilted direction from −60° to +60° in 10° increments with respect to the film normal, with the in-plane slow axis as the tilt axis (axis of rotation). Rth(λ) is calculated by AxoScan based on the measured retardation values, the assumed average refractive index, and the input film thickness. In this case, the in-plane slow axis of the film is determined by AxoScan.

[0017] In the above measurements, the assumed average refractive index can be determined from the Polymer Handbook (John Wiley & Sons, Inc.) or from catalogs of various optical compensation films. Furthermore, if the average refractive index is unknown, it can be measured using an Abbe refractometer. Examples of average refractive index values ​​for major optical compensation films are listed below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59). By inputting these assumed average refractive index values ​​and the film thickness, AxoScan calculates nx, ny, and nz. Nz = (nx - nz) / (nx - ny) is further calculated from the calculated nx, ny, and nz. Unless otherwise specified, Re, Rth, and the refractive index are measured at a wavelength of λ = 550 nm in the visible light range. In this specification, the term "major axis" refers to the major refractive index axis of the refractive index ellipsoid calculated by AxoScan. Unless otherwise specified, nx, ny, and nz refer to the major refractive index nz in the film thickness direction.

[0018] In this specification, the transmittance is measured using an Axometrics AxoScan by irradiating light with a wavelength of 550 nm.

[0019] In this specification, the degree of circular polarization is a value expressed as {|IR-IL| / (IR+IL)}×100(%), where IR is the intensity of the right-handed circularly polarized component of light and IL is the intensity of the left-handed circularly polarized component.

[0020] The degree of circular polarization can be measured using a spectroradiometer or spectrometer equipped with a circular polarizing plate. Ordinary light sources, such as incandescent lamps, mercury lamps, fluorescent lamps, and LEDs, emit almost natural light, and the polarization-producing properties of the circular polarizing filters or circular polarization separation layers attached to these can be measured using, for example, a polarization phase difference analyzer, such as AxoScan, manufactured by AXOMETRICS. Measurements can also be made by attaching a circular polarizing filter to an illuminometer or optical spectrometer. The ratio can be measured by attaching a right-handed circularly polarized light transmitting plate to measure the amount of right-handed circular polarization and attaching a left-handed circularly polarized light transmitting plate to measure the amount of left-handed circular polarization. Unless otherwise specified, the degree of circular polarization in this specification refers to the degree of circular polarization at a wavelength of 550 nm.

[0021] The optical members (first to third optical members) of the present invention will be described below. Note that, although the optical members and image display devices (AR glasses) of the present invention will be described below using examples of embodiments, the present invention is not limited to the examples shown below, and various improvements and modifications can be made without departing from the gist of the present invention.

[0022] [First Optical Member] The first optical member of the present invention is an optical member comprising: an optical film having a polarization control layer and a light-absorbing anisotropic layer; and a light guide plate disposed on the side of the optical film having the polarization control layer, and equipped with a diffraction element whose diffraction efficiency changes depending on the polarization direction, wherein the angle formed by the central axis of transmittance of the light-absorbing anisotropic layer and the normal direction of the light-absorbing anisotropic layer is 0 to 45°; the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in any one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film; the polarization control layer is a λ / 4 film; and when the optical member is arranged in a usage configuration, the angle formed by the slow axis of the λ / 4 film and the horizontal direction is 0 to 20°.

[0023] Here, the angle between the slow axis of the λ / 4 film and the horizontal direction when the optical member is arranged in a usage form means the angle between the in-plane slow axis of the λ / 4 film and the horizontal direction when using a head-mounted display (for example, an image display device such as AR glasses) including the optical member. More specifically, taking Fig. 1 described later as an example, when the optical member is used as a member of a head-mounted display, the optical member is used so that its in-plane direction is along the vertical direction as shown in Fig. 1, and the above angle means the angle between the in-plane slow axis of the λ / 4 film and the horizontal direction when used in that usage form.

[0024] An example of an embodiment of the first optical member will be described below with reference to the drawings. The configuration and function of the first optical member will be described below using an example of an image display device using the first optical member. The image display device includes the first optical member and a display element that projects an image onto an incident diffraction element in the first optical member.

[0025] Fig. 1 is a side view conceptually illustrating an example of an image display device using a first optical member. The image display device 10 shown in Fig. 1 is used as AR glasses as a suitable example. The first optical member can also be used for optical elements such as transparent screens, lighting devices (including backlights for liquid crystal displays), and sensors, in addition to AR glasses.

[0026] The image display device 10 shown in FIG. 1 includes an optical element 30 including an optical film 12 having a polarization control layer 14 and a light absorption anisotropic layer 16, a light guide element 28 disposed on the side of the optical film 12 having the polarization control layer 14, and a display element 32. The light guide element 28 includes a light guide plate 22 and an incident diffraction element 24 and an exit diffraction element 26 disposed on the principal surface of the light guide plate 22. In the image display device 10 shown in FIG. 1, the incident diffraction element 24 and the exit diffraction element 26 are disposed at different positions in the planar direction of the principal surface of the light guide plate 22, with the exit diffraction element 26 disposed below the incident diffraction element 24. Note that the principal surface refers to the largest surface of a sheet-like object (such as a plate-like object or film). The display element 32 is disposed at a position overlapping the incident diffraction element 24 in the planar direction of the principal surface of the light guide plate 22, facing the surface of the light guide plate 22 opposite the side on which the incident diffraction element 24 is disposed. The input diffraction element 24 and the output diffraction element 26 are reflective diffraction elements that diffract and reflect light. The output diffraction element 26 is a diffraction element whose diffraction efficiency varies depending on the polarization direction. In other words, the output diffraction element 26 is a polarization diffraction element that selectively diffracts polarized light and exhibits different diffraction efficiencies depending on the polarization direction of the light. Examples of the output diffraction element 24 include a diffraction element that has a high diffraction efficiency for one of right-handed polarized light (right-handed circularly polarized light) and left-handed polarized light (left-handed circularly polarized light) and a low diffraction efficiency or no diffraction for the other of right-handed polarized light (right-handed circularly polarized light) and left-handed polarized light (left-handed circularly polarized light), and a diffraction element that has a high diffraction efficiency for linearly polarized light and a low diffraction efficiency or no diffraction for circularly polarized light. In the image display device 10, an image (light corresponding to the image) displayed by the display element 32 enters the input diffraction element 24 from a direction perpendicular to the main surface of the light guide plate 22. The light that enters the input diffraction element 24 is diffracted by the input diffraction element 24 and enters the light guide plate 22. At this time, the incident diffraction element 24 diffracts the light at an angle that causes total reflection within the light guide plate 22, and also diffracts the light so that the diffracted light travels in a direction toward the output diffraction element 26. In the example shown in Figure 1, the incident diffraction element 24 diffracts the incident light in a downward direction in Figure 1. The diffracted light by the incident diffraction element 24 propagates within the light guide plate 22 while being totally reflected, and then enters the output diffraction element 6.The output diffraction element 26 diffracts the incident light at an angle that deviates from the angle at which the light is totally reflected within the light guide plate 22. In the example shown in FIG. 1 , the output diffraction element 26 diffracts the incident light toward the right side in FIG. 1 . That is, as shown in FIG. 1 , the output diffraction element 26 diffracts the incident light in a direction substantially perpendicular to the main surface of the light guide plate. The light diffracted by the output diffraction element 26 is output from the light guide plate 22 and directed toward the user U. This allows the image display device 10 to display the image illuminated by the display element 32.

[0027] The optical member 30 includes an optical film 12 having a polarization control layer 14 and a light absorption anisotropic layer 16. In the image display device 10 shown in Fig. 1, the optical film 12 is disposed on the side of the output diffraction element 26 opposite the light guide plate 22 side. In other words, the optical film 12 is disposed on the side opposite the output side of the output diffraction element 26. The optical film 12 is also disposed in a position overlapping with the output diffraction element 26 in the planar direction of the main surface of the light guide plate 22, so that the polarization control layer 14 faces the output diffraction element 26.

[0028] The optically absorptive anisotropic layer 16 has an angle of 0 to 45° between the central transmittance axis of the optically absorptive anisotropic layer 16 and the normal direction of the optically absorptive anisotropic layer 16. The optically absorptive anisotropic layer 16 typically contains a dichroic material, and the direction of the absorption axis of the dichroic material (the long axis direction of the molecule) is approximately the same as the central transmittance axis of the optically absorptive anisotropic layer 16. That is, in the optically absorptive anisotropic layer 16, the dichroic material is oriented so that its absorption axis is approximately perpendicular to the main surface. When the angle between the central transmittance axis of the optically absorptive anisotropic layer 16 and the normal direction of the optically absorptive anisotropic layer 16 is 0 to 45°, the transmittance of light incident from the front of the optical film 12 tends to be high, and when incident from an oblique direction, only S-polarized light passes through, resulting in low transmittance. The definition of the central transmittance axis of the optically absorptive anisotropic layer 16 and a method for measuring the same will be described later.

[0029] The polarization control layer 14 is a λ / 4 film, and is arranged so that the angle between the slow axis (in-plane slow axis) of the polarization control layer 14, which is a λ / 4 film, and the horizontal direction is 0 to 20 degrees. Note that the horizontal direction is the horizontal direction when the optical member is arranged in a usage configuration. More specifically, the angle refers to the angle between the slow axis (in-plane slow axis) of the polarization control layer 14 and the horizontal direction when a user properly wears a head-mounted display such as the image display device 10 and uses it properly under normal conditions. In order to further suppress deterioration of background visibility caused by external light incident from above the user U, the angle between the slow axis (in-plane slow axis) of the polarization control layer 14, which is a λ / 4 film, and the horizontal direction is preferably greater than 0 degrees and less than or equal to 20 degrees, and more preferably 5 to 15 degrees.

[0030] The optical film 12 has a degree of circular polarization of 50% or more in at least one azimuth angle in a direction that forms an angle of 60° with the normal direction of the optical film 12. In other words, when light is incident at an angle of 60° with respect to the normal direction of the optical film 12, the degree of circular polarization is 50% or more in at least one azimuth angle. The upper limit of the degree of circular polarization is not particularly limited, but is 100% or less. The degree of circular polarization is measured by irradiating light from the light absorption anisotropic layer side. When the optical film 12 has a degree of circular polarization of 50% or more in at least one azimuth angle in a direction that forms an angle of 60° with the normal direction of the optical film 12, as described below, light that passes through the polarization control layer 14 and is irradiated to the light-guiding member 28 is less likely to be diffracted, thereby improving the visibility of the background caused by external light entering from above the user U. The circular polarization degree of the optical film 12 is more preferably 60 to 100%, and even more preferably 75 to 100%, in order to provide better visibility of the background caused by external light incident from above the user U.

[0031] The transmittance in the normal direction of the optical film 12 is 55% or more. The upper limit of the transmittance in the normal direction of the optical film 12 is not particularly limited, but is 100% or less. The transmittance in a direction forming an angle of 30° with the normal direction of the optical film 12 is 25% or more. That is, the transmittance when light is incident at an angle of 30° with respect to the normal direction of the optical film 12 is 25% or more. The upper limit of the transmittance in a direction forming an angle of 30° with the normal direction of the optical film 12 is not particularly limited, but is 100% or less. The transmittance is measured by irradiating light from the optically absorptive anisotropic layer side. The transmittance can be achieved by adjusting the angle between the transmittance central axis of the optically absorptive anisotropic layer 16 and the normal direction of the optically absorptive anisotropic layer 16 to 0° to 45° and by appropriately adjusting the layer structure of the optical film 12. In addition, the optical film used in the optical component of Comparative Example 2 shown in the Examples section has two light-absorbing anisotropic layers, and therefore the transmittance in the direction forming an angle of 30° with the normal direction of the optical film does not meet the specified value.

[0032] When the image display device 10 is in use, external light (light incident from the light source 34 at an oblique angle relative to the image display device 10) incident from above the user U passes through the light absorption anisotropic layer 16 to become linearly polarized light vibrating in a predetermined direction. The light then enters the polarization control layer 14 and is converted into right-handed or left-handed circularly polarized light (however, circularly polarized light having a polarization direction with low diffraction efficiency or no diffraction by the output diffraction element 26). In other words, if the light selectively diffracted by the output diffraction element 26 is right-handed circularly polarized light, it is converted into left-handed circularly polarized light by the polarization control layer 14. The light transmitted through the polarization control layer 14 is irradiated onto the light-guiding member 28, but because the light is circularly polarized light with low diffraction efficiency or a polarization direction with no diffraction by the output diffraction element 26, diffraction by the output diffraction element 26 is suppressed, making it less likely to enter the user U's eyes. As a result, deterioration of background visibility due to external light incident from above the user U can be suppressed. As described above, it is preferable that the rotation direction of the larger component of right-handed circularly polarized light and left-handed circularly polarized light emitted through the optical member is opposite to the rotation direction of the circularly polarized light diffracted by the diffraction element. More specifically, it is preferable that the rotation direction of the larger component of right-handed circularly polarized light and left-handed circularly polarized light emitted through the optical film in a direction that forms an angle of 60° with the normal direction of the optical film so that the degree of circular polarization is 50% or more is opposite to the rotation direction of the circularly polarized light diffracted by the diffraction element.

[0033] The optical film 12 may be disposed so as to overlap at least a portion of the output diffraction element 26 when viewed from a direction perpendicular to the main surface of the light guide plate 22. However, it is preferable that the optical film 12 be disposed so as to cover the entire surface, as shown in FIG. 1 . In the example shown in FIG. 1 , the optical film 12 is disposed spaced apart from the light guide member 28. However, the present invention is not limited to this configuration, and the optical film 12 may be disposed in contact with the light guide member 28. In the example shown in FIG. 1 , the light guide member 28 is configured to include an input diffraction element 24 and an output diffraction element 26 on the main surface of the light guide plate 22. However, the light guide member 28 may further include an intermediate diffraction element. In the example shown in FIG. 1 , the light guide member 28 is configured to include reflective diffraction elements (the input diffraction element 24 and the output diffraction element 26) on the main surface of the light guide plate. However, the light guide member may be a light guide member having an input diffraction element and an output diffraction element, which are transmissive diffraction elements, on the main surface of the light guide plate.

[0034] [Second Optical Member] The second optical member of the present invention is an optical member comprising: an optical film having a polarization control layer and a light-absorbing anisotropic layer; and a light guide plate disposed on the side of the optical film having the polarization control layer, and equipped with a diffraction element whose diffraction efficiency changes depending on the polarization direction, wherein the angle formed by the central axis of transmittance of the light-absorbing anisotropic layer and the normal direction of the light-absorbing anisotropic layer is 0 to 45°, the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in any one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film, and the polarization control layer comprises a first λ / 4 film and a second λ / 4 film, and the angle formed by the slow axis of the first λ / 4 film and the slow axis of the second λ / 4 film is 30 to 60°.

[0035] An example of an embodiment of the second optical member will be described below with reference to the drawings. The configuration and function of the second optical member will be described below using an example of an image display device using the second optical member. The image display device includes the second optical member and a display element that projects an image onto an incident diffraction element in the second optical member.

[0036] Fig. 2 is a side view conceptually illustrating an example of an image display device using the second optical member. The image display device 40 shown in Fig. 2 is used as AR glasses as a suitable example. The second optical member can also be used for optical elements such as transparent screens, lighting devices (including backlights for liquid crystal displays), and sensors, in addition to AR glasses.

[0037] The image display device 40 shown in Fig. 2 has an optical member 50 including an optical film 48 having a polarization control layer 42 and a light absorption anisotropic layer 46, and a light guiding member 28 arranged on the side of the optical film 48 having the polarization control layer 42, and a display element 32. The configuration of the image display device 40 shown in Fig. 2 is the same as that of the image display device 10 shown in Fig. 1, except that the optical film 12 in the image display device 10 shown in Fig. 1 is changed to the optical film 48. Therefore, only the configuration and function of the optical member 50 will be described below.

[0038] The optical member 50 has an optical film 48 that has a polarization control layer 42 and a light absorption anisotropic layer 46. In the image display device 40 shown in Fig. 2, the optical film 48 is disposed on the side of the output diffraction element 26 opposite the light guide plate 22 side. In other words, the optical film 48 is disposed on the side opposite the output side of the output diffraction element 26. The optical film 48 is also disposed in a position that overlaps with the output diffraction element 26 in the planar direction of the main surface of the light guide plate 22, so that the polarization control layer 42 faces the output diffraction element 26.

[0039] The optically absorptive anisotropic layer 46 has an angle of 0 to 45° between the central transmittance axis of the optically absorptive anisotropic layer 46 and the normal direction of the optically absorptive anisotropic layer 46. The optically absorptive anisotropic layer 46 typically contains a dichroic material, and the direction of the absorption axis of the dichroic material (the long axis direction of the molecule) is approximately the same as the central transmittance axis of the optically absorptive anisotropic layer 46. That is, in the optically absorptive anisotropic layer 46, the dichroic material is oriented so that its absorption axis is approximately perpendicular to the main surface. When the angle between the central transmittance axis of the optically absorptive anisotropic layer 46 and the normal direction of the optically absorptive anisotropic layer 46 is 0 to 45°, the transmittance of light incident from the front of the optical film 48 tends to be high, and when incident from an oblique direction, only S-polarized light passes through, resulting in low transmittance. The definition of the central transmittance axis of the optically absorptive anisotropic layer 46 and a method for measuring the same will be described later.

[0040] The polarization control layer 42 is composed of a first λ / 4 film 44a and a second λ / 4 film 44b. The first λ / 4 film 44a and the second λ / 4 film 44b are arranged such that the angle between the slow axis (in-plane slow axis) of the first λ / 4 film 44a and the slow axis (in-plane slow axis) of the second λ / 4 film 44b is 30 to 60 degrees.

[0041] Furthermore, when the second optical member 50 is arranged in a usage configuration, the angle between the slow axis (in-plane slow axis) of the second λ / 4 film 44b and the horizontal direction is preferably 0 to 45°, more preferably 0 to 20°, and even more preferably 0 to 10°. Here, the angle between the slow axis (in-plane slow axis) of the first λ / 4 film and the horizontal direction when the optical member is arranged in a usage configuration refers to the angle between the slow axis (in-plane slow axis) of the first λ / 4 film and the horizontal direction when a head-mounted display (e.g., an image display device such as AR glasses) including the optical member is used. More specifically, this angle refers to the angle between the slow axis (in-plane slow axis) of the first λ / 4 film and the horizontal direction when a user properly wears a head-mounted display such as the image display device 40 and uses it properly under normal conditions.

[0042] By configuring the polarization control layer 42 as described above, the optical film 48 in the second optical member has the advantage that, compared to the optical film 12 in the first optical member, the angular width of the azimuthal angle at which the degree of circular polarization in the direction at an angle (polar angle) of 60° with the normal direction of the optical film 48 is 50% or more is wider.

[0043] The optical film 48 has a degree of circular polarization of 50% or more in at least one azimuth angle direction that forms a 60° angle with the normal direction of the optical film 48. In other words, when light is incident at an angle of 60° with respect to the normal direction of the optical film 48, the degree of circular polarization is 50% or more in at least one azimuth angle direction. The upper limit of the degree of circular polarization is not particularly limited, but is 100% or less. The degree of circular polarization is measured by irradiating light from the light absorption anisotropic layer side. When the optical film 48 has a degree of circular polarization of 50% or more in at least one azimuth angle direction that forms a 60° angle with the normal direction of the optical film 48, as described below, light that passes through the polarization control layer 42 and is irradiated to the light-guiding member 28 is less likely to be diffracted, resulting in excellent visibility of the background caused by external light entering from above the user U. The degree of circular polarization of the optical film 48 is more preferably 60 to 100%, and even more preferably 75 to 100%, in order to provide better visibility of the background caused by external light incident from above the user U.

[0044] The transmittance in the normal direction of the optical film 48 is 55% or more. The upper limit of the transmittance in the normal direction of the optical film 48 is not particularly limited, but is 100% or less. The transmittance in a direction forming an angle of 30° with the normal direction of the optical film 48 is 25% or more. That is, the transmittance when light is incident at an angle of 30° with respect to the normal direction of the optical film 48 is 25% or more. The upper limit of the transmittance in a direction forming an angle of 30° with the normal direction of the optical film 48 is not particularly limited, but is 100% or less. The transmittance is measured by irradiating light from the optically absorptive anisotropic layer side. The transmittance can be achieved by adjusting the angle between the transmittance central axis of the optically absorptive anisotropic layer 46 and the normal direction of the optically absorptive anisotropic layer 46 to 0° to 45° and by appropriately adjusting the layer structure of the optical film 48.

[0045] When the image display device 40 is in use, external light (light incident from the light source 34 at an oblique angle relative to the image display device 40) incident from above the user U passes through the light absorption anisotropic layer 46 to become linearly polarized light vibrating in a predetermined direction, and then enters the polarization control layer 42, where it is converted into right-handed or left-handed circularly polarized light (however, circularly polarized light having a polarization direction that is low in diffraction efficiency or not diffracted by the output diffraction element 26). In other words, if the light selectively diffracted by the output diffraction element 26 is right-handed circularly polarized light, it is converted into left-handed circularly polarized light by the polarization control layer 42. The light that passes through the polarization control layer 42 is irradiated onto the light-guiding member 28, but because the light is circularly polarized light having a polarization direction that is low in diffraction efficiency or not diffracted by the output diffraction element 26, diffraction by the output diffraction element 26 is suppressed, and the light is less likely to enter the user U's eyes. In other words, as a result, deterioration of background visibility due to external light incident from above the user U can be suppressed. As described above, it is preferable that the rotation direction of the larger component of right-handed circularly polarized light and left-handed circularly polarized light emitted through the optical member is opposite to the rotation direction of the circularly polarized light diffracted by the diffraction element. More specifically, it is preferable that the rotation direction of the larger component of right-handed circularly polarized light and left-handed circularly polarized light emitted through the optical film in a direction that forms an angle of 60° with the normal direction of the optical film so that the degree of circular polarization is 50% or more is opposite to the rotation direction of the circularly polarized light diffracted by the diffraction element.

[0046] The optical film 48 may be disposed so as to overlap at least a portion of the output diffraction element 26 when viewed from a direction perpendicular to the main surface of the light guide plate 22. However, it is preferable that the optical film 48 be disposed so as to cover the entire surface, as shown in FIG. 2 . In the example shown in FIG. 2 , the optical film 48 is disposed spaced apart from the light guide member 28. However, the present invention is not limited to this configuration, and the optical film 48 may be disposed in contact with the light guide member 28. In the example shown in FIG. 2 , the light guide member 28 is configured to include an input diffraction element 24 and an output diffraction element 26 on the main surface of the light guide plate 22. However, the light guide member 28 may further include an intermediate diffraction element. In the example shown in FIG. 2 , the light guide member 28 is configured to include reflective diffraction elements (the input diffraction element 24 and the output diffraction element 26) on the main surface of the light guide plate. However, the light guide member may be a light guide member having an input diffraction element and an output diffraction element, which are transmissive diffraction elements, on the main surface of the light guide plate. 2, the polarization control layer 42 has a two-layer structure of a first λ / 4 film 44a and a second λ / 4 film 44b, but the polarization control layer 42 may have another optically anisotropic layer between the first λ / 4 film 44a and the second λ / 4 film 44b. An example of the other optically anisotropic layer is a positive C plate.

[0047] [Third Optical Member] The third optical member of the present invention is an optical member comprising: an optical film having a polarization control layer and a light-absorbing anisotropic layer; and a light guide plate disposed on the side of the optical film having the polarization control layer, and equipped with a diffraction element whose diffraction efficiency changes depending on the polarization direction, wherein the angle formed by the central axis of transmittance of the light-absorbing anisotropic layer and the normal direction of the light-absorbing anisotropic layer is 0 to 45°, the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, in at least one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film, and the polarization control layer is one or more layers containing a liquid crystal compound having a twist structure.

[0048] An example of an embodiment of the third optical member will be described below with reference to the drawings. The configuration and function of the third optical member will be described below using an example of an image display device using the third optical member. The image display device includes the third optical member and a display element that projects an image onto the incident diffraction element of the third optical member.

[0049] Fig. 3 is a side view conceptually illustrating an example of an image display device using the third optical member. The image display device 60 shown in Fig. 3 is used as AR glasses as a suitable example. The third optical member can also be used for optical elements such as transparent screens, lighting devices (including backlights for liquid crystal displays), and sensors, in addition to AR glasses.

[0050] The image display device 60 shown in Fig. 3 has an optical member 68 including an optical film 62 having a polarization control layer 64 and a light absorption anisotropic layer 66, and a light guiding member 28 arranged on the side of the optical film 62 having the polarization control layer 64, and a display element 32. The configuration of the image display device 60 shown in Fig. 3 is the same as that of the image display device 10 shown in Fig. 1, except that the optical film 12 in the image display device 10 shown in Fig. 1 is changed to the optical film 62. Therefore, only the configuration and function of the optical member 68 will be described below.

[0051] The optical member 68 has an optical film 62 that has a polarization control layer 64 and a light absorption anisotropic layer 66. In the image display device 60 shown in Fig. 3, the optical film 62 is arranged on the side of the output diffraction element 26 opposite the light guide plate 22 side. In other words, the optical film 62 is arranged on the side opposite the output side of the output diffraction element 26. Furthermore, the optical film 62 is arranged in a position that overlaps with the output diffraction element 26 in the planar direction of the main surface of the light guide plate 22, so that the polarization control layer 64 faces the output diffraction element 26.

[0052] The optically absorptive anisotropic layer 66 has an angle of 0 to 45° between the central transmittance axis of the optically absorptive anisotropic layer 66 and the normal direction of the optically absorptive anisotropic layer 66. The optically absorptive anisotropic layer 66 typically contains a dichroic material, and the direction of the absorption axis of the dichroic material (the long axis direction of the molecule) is approximately the same as the central transmittance axis of the optically absorptive anisotropic layer 66. That is, in the optically absorptive anisotropic layer 66, the dichroic material is oriented so that its absorption axis is approximately perpendicular to the main surface. When the angle between the central transmittance axis of the optically absorptive anisotropic layer 66 and the normal direction of the optically absorptive anisotropic layer 66 is 0 to 45°, the transmittance of light incident from the front of the optical film 62 tends to be high, and when incident from an oblique direction, only S-polarized light passes through, resulting in low transmittance. The definition of the central transmittance axis of the optically absorptive anisotropic layer 66 and a method for measuring the same will be described later.

[0053] The polarization control layer 64 is one or more layers containing a liquid crystal compound having a twist structure (hereinafter also referred to as a "twist layer"). Specifically, the twist layer is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction (the twist angle of the liquid crystal compound is typically 360° or less, preferably less than 360°), and has the function of rotating linearly polarized light that is incident perpendicularly to the plane of the twist layer.

[0054] Furthermore, when the third optical member 68 is arranged in a usage configuration, the angle between the slow axis (in-plane slow axis) of the twist layer on the optically absorptive anisotropic layer 62 side and the horizontal direction is preferably 5 to 75°, more preferably 5 to 45°, and even more preferably 10 to 35°. Here, the angle between the slow axis (in-plane slow axis) of the twist layer on the optically absorptive anisotropic layer 62 side and the horizontal direction when the optical member is arranged in a usage configuration refers to the angle between the slow axis (in-plane slow axis) of the twist layer on the optically absorptive anisotropic layer 62 side and the horizontal direction when a head-mounted display (e.g., an image display device such as AR glasses) including the optical member is used. More specifically, this angle refers to the horizontal direction when a user properly wears a head-mounted display such as the image display device 60 and uses it properly under normal conditions.

[0055] The optical film 62 has a degree of circular polarization of 50% or more in at least one azimuth angle in a direction that forms a 60° angle with the normal direction of the optical film 62. In other words, when light is incident at an angle of 60° with respect to the normal direction of the optical film 62, the degree of circular polarization is 50% or more in at least one azimuth angle. The upper limit of the degree of circular polarization is not particularly limited, but is 100% or less. The degree of circular polarization is measured by irradiating light from the light absorption anisotropic layer side. When the optical film 62 has a degree of circular polarization of 50% or more in at least one azimuth angle in a direction that forms a 60° angle with the normal direction of the optical film 62, as described below, light that passes through the polarization control layer 64 and is irradiated to the light-guiding member 28 is less likely to be diffracted, thereby improving the visibility of the background caused by external light entering from above the user U. The circular polarization degree of the optical film 62 is more preferably 60 to 100%, and even more preferably 75 to 100%, in order to provide better visibility of the background caused by external light incident from above the user U.

[0056] The transmittance in the normal direction of the optical film 62 is 55% or more. The upper limit of the transmittance in the normal direction of the optical film 62 is not particularly limited, but is 100% or less. The transmittance in a direction forming an angle of 30° with the normal direction of the optical film 62 is 25% or more. That is, the transmittance when light is incident at an angle of 30° with respect to the normal direction of the optical film 62 is 25% or more. The upper limit of the transmittance in a direction forming an angle of 30° with respect to the normal direction of the optical film 62 is not particularly limited, but is 100% or less. The transmittance is measured by irradiating light from the optically absorptive anisotropic layer side. The transmittance can be achieved by adjusting the angle between the transmittance central axis of the optically absorptive anisotropic layer 66 and the normal direction of the optically absorptive anisotropic layer 66 to 0° to 45° and by appropriately adjusting the layer structure of the optical film 62.

[0057] When the image display device 60 is in use, external light (light incident from the light source 34 at an oblique angle relative to the image display device 60) incident from above the user U passes through the light absorption anisotropic layer 66 to become linearly polarized light vibrating in a predetermined direction, and then enters the polarization control layer 64, where it is converted into right-handed or left-handed circularly polarized light (however, circularly polarized light having a polarization direction with low diffraction efficiency or no diffraction by the output diffraction element 26). In other words, if the light selectively diffracted by the output diffraction element 26 is right-handed circularly polarized light, it is converted into left-handed circularly polarized light by the polarization control layer 64. The light that passes through the polarization control layer 64 is irradiated onto the light-guiding member 28, but because the light is circularly polarized light with low diffraction efficiency or a polarization direction with no diffraction by the output diffraction element 26, diffraction by the output diffraction element 26 is suppressed, and the light is less likely to enter the user U's eyes. In other words, as a result, deterioration in background visibility due to external light incident from above the user U can be suppressed. As described above, it is preferable that the rotation direction of the larger component of right-handed circularly polarized light and left-handed circularly polarized light emitted through the optical member is opposite to the rotation direction of the circularly polarized light diffracted by the diffraction element. More specifically, it is preferable that the rotation direction of the larger component of right-handed circularly polarized light and left-handed circularly polarized light emitted through the optical film in a direction that forms an angle of 60° with the normal direction of the optical film so that the degree of circular polarization is 50% or more is opposite to the rotation direction of the circularly polarized light diffracted by the diffraction element.

[0058] The optical film 62 may be disposed so as to overlap at least a portion of the output diffraction element 26 when viewed from a direction perpendicular to the main surface of the light guide plate 22. However, it is preferable that the optical film 62 be disposed so as to cover the entire surface, as shown in FIG. 3 . In the example shown in FIG. 3 , the optical film 62 is disposed spaced apart from the light guide member 28. However, the present invention is not limited to this configuration, and the optical film 62 may be disposed in contact with the light guide member 28. In the example shown in FIG. 3 , the light guide member 28 is configured to include an input diffraction element 24 and an output diffraction element 26 on the main surface of the light guide plate 22. However, the light guide member 28 may further include an intermediate diffraction element. In the example shown in FIG. 3 , the light guide member 28 is configured to include reflective diffraction elements (the input diffraction element 24 and the output diffraction element 26) on the main surface of the light guide plate. However, the light guide member may be a light guide member having an input diffraction element and an output diffraction element, which are transmissive diffraction elements, on the main surface of the light guide plate. 3, the polarization control layer 64 is a single-layer twisted layer, but the polarization control layer 64 may be a laminate of two or more twisted layers, or may further include another optically anisotropic layer on the side of the twisted layer opposite the light absorption anisotropic layer. An example of the other optically anisotropic layer is a positive C plate.

[0059] [Each component of the optical member] <Optical film> (Polarization control layer) The polarization control layer used in the optical member of the present invention is a layer that can polarize and control linearly polarized light incident obliquely to the plane of the polarization control layer into circularly polarized light. In particular, it is preferable that the linearly polarized light can be more circularly polarized when incident from an oblique direction that forms an angle of 40° or more with the normal direction of the polarization control layer. Note that typical examples of polarization control layers that circularly polarize linearly polarized light include λ / 4 films and twist layers.

[0060] The λ / 4 film used in the optical member of the present invention refers to a retardation layer having an in-plane retardation of about ¼ of the wavelength, specifically a retardation layer having an in-plane retardation Re(550) of 100 nm to 180 nm at a wavelength of 550 nm. Furthermore, the Rth of the λ / 4 film used in the optical member of the present invention is preferably −200 nm to 400 nm.

[0061] The λ / 4 film used in the optical member of the present invention is not particularly limited as long as the in-plane retardation is about ¼ of the wavelength, but is preferably a layer formed using a composition containing a liquid crystal compound.

[0062] Generally, liquid crystal compounds can be classified into rod-shaped and discotic types based on their shape. Furthermore, each can be divided into low-molecular-weight and high-molecular-weight types. High-molecular-weight compounds generally refer to those with a degree of polymerization of 100 or more (see "Polymer Physics: Phase Transition Dynamics," by Masao Doi, p. 2, Iwanami Shoten, 1992). While any liquid crystal compound can be used in the optical element of the present invention, rod-shaped or discotic liquid crystal compounds (discotic liquid crystal compounds) are preferred. Furthermore, monomers or liquid crystal compounds with relatively low molecular weights and a degree of polymerization of less than 100 are preferred. Examples of polymerizable groups possessed by polymerizable liquid crystal compounds include acryloyl groups, methacryloyl groups, epoxy groups, and vinyl groups. The orientation of such polymerizable liquid crystal compounds can be fixed by polymerization. After the liquid crystal compound is fixed by polymerization, it no longer needs to exhibit liquid crystallinity.

[0063] Preferred rod-shaped liquid crystal compounds include azomethines, azoxy compounds, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. These rod-shaped liquid crystal compounds are fixed by introducing a polymerizable group into the terminal structure of the rod-shaped liquid crystal compound (as with the discotic liquid crystals described below), followed by polymerization and curing. A specific example is described in JP-A No. 2006-209073, in which a polymerizable nematic rod-shaped liquid crystal compound is cured with ultraviolet light. In addition to the low-molecular-weight liquid crystal compounds described above, polymeric liquid crystal compounds can also be used. Polymeric liquid crystal compounds are polymers having side chains corresponding to the low-molecular-weight liquid crystal compounds described above. Optical compensation sheets using polymeric liquid crystal compounds are described in JP-A No. 5-053016, for example.

[0064] Examples of discotic liquid crystal compounds include benzene derivatives described in the research report by C. Destrade et al., Mol. Cryst., Vol. 71, p. 111 (1981), truxene derivatives described in the research report by C. Destrade et al., Mol. Cryst., Vol. 122, p. 141 (1985) and Physicslett, A, Vol. 78, p. 82 (1990), cyclohexane derivatives described in the research report by B. Kohne et al., Angew. Chem., Vol. 96, p. 70 (1984), and compounds described in the research report by J. M. Lehn et al., J. Chem. Commun., p. 1794 (1985), and the research report by J. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994) include azacrown and phenylacetylene macrocycles.

[0065] The discotic liquid crystal compound molecules also include compounds exhibiting liquid crystallinity in which linear alkyl groups, alkoxy groups, or substituted benzoyloxy groups are radially substituted as side chains around the mother nucleus at the center of the molecule. The molecules or molecular aggregates are preferably compounds that have rotational symmetry and can impart a certain orientation. A retardation layer formed from a composition containing a discotic liquid crystal compound does not necessarily exhibit liquid crystallinity when finally incorporated into the retardation layer. For example, low-molecular-weight discotic liquid crystal molecules having heat- or light-reactive groups lose their liquid crystallinity when polymerized by heating or light irradiation. However, retardation layers containing such highly polymerized compounds can also be used in the optical element of the present invention. Preferred examples of discotic liquid crystal compounds include those described in JP-A-8-050206. Furthermore, the polymerization of discotic liquid crystal molecules is described in JP-A-8-027284.

[0066] In order to fix discotic liquid crystal molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystal molecule. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferred, and this allows the alignment state to be maintained even during the polymerization reaction. Examples thereof include compounds described in paragraphs

[0151] to

[0168] of JP-A No. 2000-155216.

[0067] The liquid crystal compound may have forward wavelength dispersion or reverse wavelength dispersion.

[0068] C Plates There are two types of C plates used in the optical member of the present invention: 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). A positive C plate exhibits a negative Rth, while a negative C plate exhibits a positive Rth. Formula (C1) nz>nx≒ny Formula (C2) nz<nx≒ny Note that the above "≒" encompasses not only the case where the two are completely identical, but also the case where the two are substantially identical. The term "substantially identical" refers to the case where (nx-ny)×d is 0 to 10 nm, preferably 0 to 5 nm, as "nx≒ny." Note that in (ny-nz)×d, d is the film thickness.

[0069] The Rth of the C plate used in the optical member of the present invention is preferably −500 nm to −10 nm, or 10 nm to 500 nm.

[0070] <<Twist Layer>> The twist layer used in the optical element of the present invention is a layer formed by fixing a liquid crystal compound twisted and aligned along a helical axis extending in the thickness direction. The twist layer is an optical element having optical rotation. Having optical rotation means that linearly polarized light propagates through a medium while rotating substantially linearly polarized light. Therefore, the twist layer has the function of rotating linearly polarized light incident perpendicularly to the plane of the twist layer. The twist angle of the liquid crystal compound in the twist layer is not particularly limited, but is preferably 20 to 360°. The twist angle is measured using an Axometrics AxoScan (polarimeter) device and the company's device analysis software. The Δnd of the retardation layer is not particularly limited, but is preferably 200 to 1000 nm. Δn represents the refractive index anisotropy of the retardation layer at a wavelength of 550 nm, and d represents the thickness (nm) of the retardation layer.

[0071] From the viewpoint of ease of production, the refractive index anisotropic layer having a twist structure is preferably a film having a twist structure formed by adding a chiral agent to a rod-shaped or discotic liquid crystal compound. Furthermore, in terms of achieving a thin film, it can be made thinner than a retardation film using a polymer. On the other hand, when using a polymer film, obtaining a twist structure and optical rotation is difficult in terms of manufacturing, for example, by laminating multiple polymer films with the slow axes of the polymer films at slightly different angles in-plane. However, the polymer film is preferably a cellulose acylate film, a cycloolefin polymer film (a polymer film using a cycloolefin polymer), a polycarbonate polymer film, a polystyrene polymer film, or an acrylic polymer film. The acrylic polymer film preferably contains an acrylic polymer containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit.

[0072] (Lightly Absorbing Anisotropic Layer) The lightly absorptive anisotropic layer contains a dichroic dye, and the absorption axis of the dichroic dye forms an angle of 0 to 45° with the normal to the main surface.

[0073] By orienting the absorption axis of the optically absorptive anisotropic layer substantially perpendicular to the main surface, the transmittance is high when viewed from the front and low when viewed from an oblique angle, since only S-polarized light passes through. On the other hand, by orienting the absorption axis of the optically absorptive anisotropic layer parallel to the main surface, it is possible to obtain an optically absorptive anisotropic layer having optical performance similar to that of a commonly known iodine-based polarizer, which is obtained by impregnating a stretched PVA (polyvinyl alcohol) film with polyiodine ions.

[0074] Here, the fact that the absorption axis of the optically absorptive anisotropic layer is oriented in a direction approximately perpendicular to the main surface (horizontal reference plane) can be confirmed, for example, by observing a cross section of the optically absorptive anisotropic layer with a transmission electron microscope (TEM).

[0075] The technology for orienting the dichroic dye in the desired direction can be based on the technology for producing a polarizer using a dichroic dye, the technology for producing a guest-host liquid crystal cell, etc. For example, the technology used in the method for producing a dichroic polarizing element described in JP-A-2002-090526 and the method for producing a guest-host liquid crystal display device described in JP-A-2002-099388 can also be used to produce the light-absorption anisotropic layer used in the optical member of the present invention.

[0076] Dichroic dyes can be classified into those with rod-shaped molecules and those with disc-shaped molecules. Either type may be used in the preparation of the light absorption anisotropic layer used in the optical component of the present invention. Preferred examples of dichroic dyes with rod-shaped molecules include azo dyes, anthraquinone dyes, perylene dyes, and mericyanin dyes. For example, examples of azo dyes include those described in JP-A-11-172252, examples of anthraquinone dyes include those described in JP-A-8-067822, examples of perylene dyes include those described in JP-A-62-129380, and examples of mericyanin dyes include those described in JP-A-2002-241758. These may be used alone or in combination of two or more.

[0077] Examples of dichroic dyes with discotic molecules include lyotropic liquid crystals, such as those manufactured by OPTIVA Inc., and are known to be used as "E-type polarizers." Examples include the materials described in JP 2002-090547 A. Similarly, examples of dichroic dyes that use a wormlike micelle structure as a chemical structure that absorbs light in a discotic manner include the materials described in JP 2002-090526 A. These may be used alone or in combination of two or more. In the case of an "E-type polarizer" using a discotic dichroic dye, it is possible to block oblique external light without combining it with a polarizer whose absorption axis is within the principal plane.

[0078] Among them, rod-shaped dichroic dyes are preferred because they can easily achieve a high degree of orientation.

[0079] For example, by utilizing the technology of a guest-host liquid crystal cell, the dichroic dye molecules can be aligned in the desired orientation as described above in association with the alignment of the host liquid crystal. Specifically, a light absorption anisotropic layer can be produced by mixing a dichroic dye as a guest with a rod-shaped liquid crystal compound as a host liquid crystal, aligning the host liquid crystal, and aligning the dichroic dye molecules along the alignment of the liquid crystal molecules, and then fixing the alignment state.

[0080] In order to prevent the light absorption characteristics of the light absorption anisotropic layer from varying depending on the use environment, it is preferable to fix the orientation of the dichroic dye by forming a chemical bond, for example, by promoting polymerization of the host liquid crystal, the dichroic dye, or a polymerizable component added as needed.

[0081] Alternatively, a guest-host liquid crystal cell having a liquid crystal layer containing at least a dichroic dye and a host liquid crystal between a pair of substrates may be used as the optically absorptive anisotropic layer. The orientation of the host liquid crystal and the accompanying orientation of the dichroic dye molecules can be controlled by an alignment film formed on the inner surface of the substrate. This orientation state is maintained unless an external stimulus such as an electric field is applied, thereby making it possible to maintain the optical absorption characteristics of the optically absorptive anisotropic layer.

[0082] Furthermore, by infiltrating a dichroic dye into a polymer film and orienting the dichroic dye along the orientation of the polymer molecules in the polymer film, a polymer film that satisfies the light absorption characteristics required for the light absorption anisotropic layer can be produced. Specifically, a solution of the dichroic dye can be applied to the surface of the polymer film and then infiltrated into the film. The orientation of the dichroic dye can be adjusted by the orientation of the polymer chains in the polymer film, the properties of the polymer chains, the coating method, etc. The properties of the polymer chains refer to the chemical and physical properties of the polymer chains or the functional groups possessed by the polymer chains. Details of this method are described in JP 2002-090526 A.

[0083] In this specification, a dichroic dye (dichroic material) is defined as a compound that has the function of absorbing light. The dichroic dye may have any absorption maximum and absorption band, but preferably has an absorption maximum in the yellow (Y), magenta (M), or cyan (C) range. Two or more dichroic dyes may be used, and a mixture of dichroic dyes having an absorption maximum in any of the Y, M, and C ranges is preferably used. It is more preferable to mix dichroic dyes so as to absorb light over the entire visible range (400 to 750 nm). Here, the yellow range refers to a wavelength range of 430 to 500 nm, the magenta range refers to a wavelength range of 500 to 600 nm, and the cyan range refers to a wavelength range of 600 to 750 nm.

[0084] The thickness of the optically absorptive anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.3 to 5 μm, and even more preferably 0.5 to 3 μm. By making the optically absorptive anisotropic layer 0.1 μm or more, diffracted light generated by oblique incidence can be sufficiently blocked. By making the optically absorptive anisotropic layer 10 μm or less, the transmittance of external light from the front (front external light I0) can be made sufficient, and background visibility can be suitably ensured.

[0085] -Method for producing optically absorptive anisotropic layer- The method for producing the optically absorptive anisotropic layer is not particularly limited as long as it can align the dichroic dye so that the major axis thereof is perpendicular to the surface (horizontal surface) of the substrate, and can be appropriately selected depending on the purpose. Examples include (1) a guest-host liquid crystal method, (2) an anodic alumina method, (3) control of the surface energy of the substrate, and (4) use of a surfactant.

[0086] The guest-host liquid crystal method (1) is a method in which an absorbing layer coating liquid containing at least an ultraviolet-curable liquid crystal compound and a dichroic dye is coated on a substrate having an alignment film on its surface, and dried to form a coating layer. The coating layer is heated to a temperature at which a liquid crystal phase is expressed, and then irradiated with ultraviolet light to form a light-absorbing anisotropic layer in which the major axis of the dichroic dye is oriented in a direction approximately perpendicular to the substrate surface.

[0087] The central axis of transmittance of the optically absorbing anisotropic layer refers to the direction showing the highest transmittance when the transmittance is measured by changing the tilt angle (polar angle) and tilt direction (azimuth angle) relative to the normal direction of the optically absorbing anisotropic layer surface. Specifically, the Mueller matrix at a wavelength of 550 nm is measured using an AxoScan OPMF-2 (manufactured by Axometrics). More specifically, during measurement, the azimuth angle at which the central axis of transmittance is tilted is first found, and then, within a plane containing the normal direction of the optically absorbing anisotropic layer along that azimuth angle (a plane containing the central axis of transmittance and perpendicular to the layer surface), the polar angle, which is the angle relative to the normal direction of the optically absorbing anisotropic layer surface, is changed in 1° increments from -70 to 70°, and the Mueller matrix at a wavelength of 550 nm is measured, thereby deriving the transmittance of the optically absorbing anisotropic layer. As a result, the direction with the highest transmittance is designated as the central axis of transmittance. The transmittance central axis means the direction of the absorption axis (the direction of the long axis of the molecule) of the dichroic material contained in the light absorption anisotropic layer.

[0088] (Polarizer) The optical film may include a polarizer. The polarizer is a polarizer whose absorption axis is in the main plane. That is, the absorption axis of the polarizer is parallel to the main plane. By including a polarizer in the optical film, as described above, the optical film can effectively absorb oblique external light I s Since it acts like a polarizer arranged in crossed Nicols with respect to oblique external light I s The polarizer can block (absorb) light. Various known polarizers whose absorption axis is parallel to the principal surface can be used. Examples include an iodine-based polarizer in which a stretched PVA film is impregnated with polyiodine ions, a dye-based polarizer in which a stretched PVA film is impregnated with a dichroic dye, and the above-mentioned optically absorptive anisotropic layer exhibiting optical performance in which the absorption axis of the optically absorptive anisotropic layer is oriented parallel to the principal surface.

[0089] (Retardation Layer) The optical film may further have a retardation layer. When the optical film has a retardation layer, it is possible to prevent oblique external light I s By adjusting the polarization direction of the oblique external light I, the optical film can sAs a result, when the optical film has a retardation layer, it is possible to suppress visibility problems caused by external light incident from diagonally forward above the head (diagonally forward above the head).

[0090] The optical film may further include, as necessary, a protective layer, an oxygen barrier layer, an adhesive layer such as a pressure-sensitive adhesive layer or a bonding layer, an ultraviolet absorbing layer, and a layer that absorbs specific visible light such as a blue light absorbing layer.

[0091] <Light Guide Member> (Light Guide Plate) The light guide plate is a known light guide plate that reflects and guides (propagates) light that has entered the interior. There are no particular limitations on the light guide plate, and various known light guide plates used in AR glasses, backlight units for liquid crystal displays, etc. can be used.

[0092] (Diffraction Element) A polarization diffraction element can be used as the diffraction element (e.g., incident diffraction element, intermediate diffraction element, and exit diffraction element) used in the optical member of the present invention. Known polarization diffraction elements can be used as the polarization diffraction element. A polarization diffraction element is a diffraction element that controls the diffraction direction, polarization state, and diffracted light intensity of exiting light according to the polarization state of incident light by controlling the polarization state in a fine region. In other words, a polarization diffraction element is a diffraction element whose diffraction efficiency changes depending on the polarization direction. Among polarization diffraction elements, an element that diffracts circularly polarized light is preferable. Polarization diffraction elements can include, for example, diffraction elements that form a diffraction structure using structural birefringence, such as relief-type diffraction elements and volume hologram diffraction elements, as well as various known diffraction elements such as liquid crystal diffraction elements. A suitable example of the liquid crystal diffraction element is a liquid crystal diffraction element formed using a composition containing a liquid crystal compound and having a liquid crystal orientation pattern in which the orientation of the optical axis derived from the liquid crystal compound changes while continuously rotating along at least one direction in the plane. Another suitable example of the liquid crystal diffraction element is a diffraction element having a cholesteric liquid crystal layer in which a cholesteric liquid crystal phase is fixed.

[0093] As a diffraction element whose diffraction efficiency changes depending on the polarization direction, a liquid crystal diffraction element is particularly preferred. As the liquid crystal diffraction element, for example, the liquid crystal diffraction element described in paragraphs

[0070] to

[0143] of WO 2021 / 106749 can also be preferably used.

[0094] In this specification, the slit direction refers to the direction of the structure that generates diffraction in a diffraction element (diffraction grating). Examples of structures that generate diffraction include grooves, protrusions, boundaries with different liquid crystal orientation structures, boundaries with different refractive indices, and boundaries with different transmittances. Specifically, when the diffraction element is a diffraction element having a physical groove shape, such as a surface relief diffraction element or a holographic surface diffraction element, the slit direction is the extension direction (longitudinal direction) of the grooves that form the diffraction element. When the diffraction element is a diffraction element having high refractive index regions and low refractive index regions, such as a transmission volume phase holographic diffraction element, the slit direction is the extension direction of the boundary between the high refractive index region and the low refractive index region. When the diffraction element is a liquid crystal diffraction element, the slit direction is the direction in which the orientation direction of the liquid crystal compound is uniform within any plane in the thickness direction of the diffraction element. For example, as shown in FIG. 7 of International Publication No. 2021 / 106749, in a liquid crystal diffraction element having a liquid crystal orientation pattern in which liquid crystal compound 40 continuously rotates in the direction of arrow X, the Y direction, which is perpendicular to the direction of arrow X and in which the orientation direction of liquid crystal compound 40 is uniform, is the slit direction.

[0095] External light incident obliquely on the diffraction element of AR glasses is often external light that enters the AR glasses from above (particularly from above and in front of the head), such as sunlight and indoor lighting. That is, when this external light is diffracted by the diffraction element and reaches the user's observation position, visibility problems are likely to occur. Here, a diffraction element with a slit direction close to horizontal is likely to diffract external light incident from above (particularly from above and in front of the head) in the direction of the user's observation position through the light guide plate. Therefore, when the optical component of the present invention has multiple diffraction elements, it is preferable to provide an optical film on at least the diffraction element with the slit direction closest to horizontal.

[0096] [Image Display Device] The first to third optical members are preferably applied to a head-mounted display (for example, an image display device such as AR glasses), and more preferably to AR glasses. The image display device of the present invention is typically configured to include the above-mentioned optical member (any of the first to third optical members) and a display element that projects an image onto the incident diffraction element in the optical member. The display element displays an image (video) to be observed by the user U and projects the image onto the incident diffraction element. Therefore, the display element is positioned so that the projected image is incident on the incident diffraction element. Various components of the image display device will be described below.

[0097] <Optical Member> The optical member may be any one of the first to third optical members described above.

[0098] <Display Element> The type of display element is not particularly limited, and various known display elements (display devices, projectors) used in AR glasses and the like can be used. An example of the display element is a display element having a display and a projection lens. In the image display device, the display is not particularly limited, and various known displays used in AR glasses and the like can be used. Examples of displays include liquid crystal displays (including LCOS (Liquid Crystal on Silicon)), organic electroluminescence displays, and scanning displays using DLP (Digital Light Processing) and MEMS (Micro Electro Mechanical Systems) mirrors. Note that, when the image display device is configured to display multicolor images, a display that displays multicolor images is used. Furthermore, when the image display device has multiple optical elements, a display that displays multicolor images using light of wavelengths diffracted by each diffractive element of each optical element is used. In the display element, a known projection lens (collimating lens) used in AR glasses and the like can also be used as the projection lens. The image displayed by the display element (i.e., the light emitted by the display element) is not particularly limited, but is preferably unpolarized (natural light) or circularly polarized light. When the display element emits circularly polarized light and the display emits an unpolarized image, the display element preferably has a circular polarizing plate composed of, for example, a linear polarizer and a λ / 4 plate. When the display emits a linearly polarized image, the display element preferably has, for example, a λ / 4 plate. Note that the light emitted by the display element may be other polarized light (for example, linearly polarized light, etc.).

[0099] The present invention will be described in more detail below with reference to the following 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 following examples.

[0100] Example 1 (Preparation of Optical Member A1) An optical member A1 of Example 1 was prepared according to the following procedure: The optical member A1 corresponds to the first optical member described in the upper part.

[0101] [Preparation of Optically Absorbent Anisotropic Layer 1] Optically absorptive anisotropic layer 1 was prepared by the following procedure.

[0102] <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.

[0103] ------------------------------------------------------------------ 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

[0104] 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)

[0105] Acid generator PAG-1

[0106] Stabilizer DIPEA

[0107] <Formation of Optically Absorbent Anisotropic Layer 1> The following composition P1 for forming an optically absorbent anisotropic layer 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 P1 was heated at 85°C for 60 seconds and cooled to room temperature again. Thereafter, the composition P1 was irradiated with an LED lamp (center wavelength 365 nm) from the direction normal to the film at an illuminance of 200 mW / cm. ２ The alignment film AL1 was irradiated for 2 seconds under the irradiation conditions of 1.5 μm to form an optically absorbing anisotropic layer 1 on the alignment film AL1. The film thickness of the optically absorbing anisotropic layer 1 was 4.5 μm. Hereinafter, the film provided with the optically absorbing anisotropic layer 1 prepared above will also be referred to as "optically absorbing anisotropic film 1."

[0108] <Measurement of the central axis of transmittance of optically absorbing anisotropic layer 1> The optically absorbing anisotropic film 1 produced in the upper section was placed horizontally on the sample stage, and the transmittance was measured using an AxoScan OPMF-2 (manufactured by Axometrics) while varying the azimuthal angle and polar angle of light incident on this film, as described above, to determine the azimuthal angle and polar angle of the central axis of transmittance of optically absorbing anisotropic layer 1. The central axis of transmittance of optically absorbing anisotropic layer 1 was in the direction of a polar angle of 0°.

[0109] 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 ----------------------------------------------------------------------------------

[0110] Dichroic substance D-1

[0111] Dichroic substance D-2

[0112] Dichroic substance D-3

[0113] Polymeric liquid crystal compound P-1 (wherein the numerical value for each repeating unit in the main chain represents the content (% by mass) of each repeating unit relative to all repeating units)

[0114] 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]

[0115] Orientation agent E-1

[0116] Orientation agent E-2

[0117] Surfactant F-2 (wherein the numerical value for each repeating unit represents the content (% by mass) of each repeating unit relative to all repeating units.)

[0118] TMS represents a trimethylsilyl group.

[0119] [Formation of Protective Layer B1] The following protective layer-forming composition B1 was continuously applied onto the obtained optically absorptive anisotropic layer 1 using a wire bar to form a coating film. Next, the support on which the coating film had been formed was 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. The thickness of the protective layer B1 was 0.5 μm. By the above procedure, a laminate 1 having a configuration of cellulose acylate film 1 with an alignment film / optically absorptive anisotropic layer 1 / protective layer B1 was obtained.

[0120] -------------------------------------------------- Protective layer-forming composition B1 -------------------------------------------------- 3.80 parts by mass of modified polyvinyl alcohol PVA-1 shown below 0.20 parts by mass Omnirad 2959 (IGM Resins B.V.) 0.08 parts by mass of dye compound G-1 shown below Water 70 parts by mass Methanol 30 parts by mass --------------------------------------------------

[0121] Modified polyvinyl alcohol PVA-1 (wherein the numerical value for each repeating unit represents the content (% by mass) of each repeating unit relative to all repeating units)

[0122] Dye compound G-1

[0123] [Preparation of λ / 4 Film] [Synthesis of Polymer P-1] Polymer P-1 was synthesized using monomer mA-1 and monomer mB-1 as raw material monomers.

[0124] <Synthesis of Monomer mA-1> 4-Aminocyclohexanol (50.0 g), triethylamine (48.3 g), and N,N-dimethylacetamide (800 g) were weighed into a 2 L three-neck flask equipped with a stirring blade, a thermometer, a dropping funnel, and a reflux condenser, and the mixture was stirred under ice cooling. Next, methacrylic acid chloride (47.5 g) was added dropwise to the flask over 40 minutes using the dropping funnel, and after the addition was completed, the reaction solution was stirred at 40°C for 2 hours. After the reaction solution was cooled to room temperature (23°C), the reaction solution was suction filtered to remove precipitated salts. The resulting organic layer was transferred to a 2 L three-neck flask equipped with a stirring blade, a thermometer, a dropping funnel, and a reflux condenser, and the mixture was stirred under water cooling. Next, N,N-dimethylaminopyridine (10.6 g) and triethylamine (65.9 g) were added to the flask, and 4-n-octyloxycinnamic acid chloride (127.9 g) previously dissolved in tetrahydrofuran (125 g) was added dropwise to the flask over 30 minutes using a dropping funnel. After the dropwise addition was completed, the reaction solution was stirred at 50°C for 6 hours. After the reaction solution was cooled to room temperature, it was separated and washed with water. The resulting organic layer was dried over anhydrous magnesium sulfate, and the resulting solution was concentrated to obtain a yellow-white solid. The obtained yellow-white solid was dissolved in methyl ethyl ketone (400 g) with heating and recrystallized to obtain 76 g of Monomer mA-1 shown below as a white solid (yield 40%).

[0125]

[0126] <Monomer mB-1> Cyclomer M-100 (manufactured by Daicel Corporation) having the following structure was used as monomer mB-1.

[0127]

[0128] <Synthesis of Polymer P-1> A flask equipped with a condenser, thermometer, and stirrer was charged with 2-butanone (5 parts by mass) as a solvent, and refluxed by heating in a water bath while flowing nitrogen into the flask at 5 mL / min. To this, a solution containing monomer mA-1 (1.2 parts by mass), monomer mB-1 (8.8 parts by mass), 2,2'-azobis(isobutyronitrile) (1 part by mass) as a polymerization initiator, and 2-butanone (5 parts by mass) as a solvent was added dropwise over 3 hours, and the resulting reaction solution was stirred while maintaining the reflux state for another 3 hours. After completion of the reaction, the reaction solution was allowed to cool to room temperature, and the reaction solution was diluted by adding 2-butanone (30 parts by mass) to obtain a polymer solution with a polymer concentration of approximately 20% by mass. The obtained polymer solution was poured into a large excess of methanol to precipitate the polymer, and the precipitate was filtered off. The obtained solid was washed with a large amount of methanol and then dried with air at 50 ° C. for 12 hours to obtain polymer P-1 having a photoalignable group.

[0129] [Production of λ / 4 Film] <Preparation of Composition for Photo-Alignment Film> Composition 3 for photo-alignment film was prepared as follows. --------------------------------------------------- Photo-alignment film composition 3 --------------------------------------------------- Polymer P-1 above 100.00 parts by mass Thermal acid generator D-1 below 3.00 parts by mass Diisopropylethylamine 0.60 parts by mass Butyl acetate 953.12 parts by mass Methyl ethyl ketone 238.28 parts by mass ---------------------------------------------------

[0130] Thermal acid generator D-1

[0131] The prepared composition 3 for a photo-alignment film was sealed in a glass bottle and stored in a sealed state at room temperature for 7 days.

[0132] <Formation of λ / 4 Layer> The composition 3 for a photo-alignment film that had been stored for 7 days was applied to one side of a 40 μm-thick cellulose acylate film (TAC substrate; manufactured by Fujifilm Corporation, TG40) using a bar coater. Thereafter, the film coated with the composition 3 for a photo-alignment film was dried on a hot plate at 125° C. for 2 minutes to remove the solvent, thereby forming a precursor film with a thickness of 0.15 μm. The obtained precursor film was irradiated with polarized ultraviolet light (8 mJ / cm ２ , an ultra-high pressure mercury lamp was used) to form a photo-alignment film 3. Next, the following retardation layer coating solution B was applied onto the photo-alignment film 3 using a bar coater. The coating film formed on the photo-alignment film 3 was heated to 120°C with hot air, and then cooled to 60°C. After that, a high-pressure mercury lamp was used to apply 100 mJ / cm at a wavelength of 365 nm under a nitrogen atmosphere. ２ The coating film was irradiated with ultraviolet light of 500 mJ / cm 2 while being heated to 120°C. ２ The coating film was irradiated with ultraviolet light of 1000 kJ / cm. The alignment of the liquid crystal compound was fixed by the above procedure, and a λ / 4 layer was produced. The resulting laminate (cellulose acylate film / photo-alignment film 3 / λ / 4 layer) had an Re(550) of 140 nm and an Rth(550) of 80 nm, making it a λ / 4 film.

[0133] ------------------------------------------------ Coating solution B for retardation layer ------------------------------------------------ - 39.00 parts by mass of polymerizable liquid crystal compound L-1 described below - 39.00 parts by mass of polymerizable liquid crystal compound L-2 described below - 17.00 parts by mass of polymerizable liquid crystal compound L-3 described below - 5.00 parts by mass of polymerizable liquid crystal compound A-1 described below - 0.50 parts by mass of polymerization initiator S-1 (oxime type) described below - 0.20 parts by mass of surfactant F-3 described below - 235.00 parts by mass of cyclopentanone ------------------------------------------------

[0134] Polymerizable liquid crystal compound L-1

[0135] Polymerizable liquid crystal compound L-2

[0136] Polymerizable liquid crystal compound L-3

[0137] Polymerizable liquid crystal compound A-1

[0138] Polymerization initiator S-1

[0139] Surfactant F-3 (wherein the numerical value attached to each repeating unit in the main chain indicates the content (% by mass) of each repeating unit relative to all repeating units.)

[0140] [Preparation of Optical Film 1] The surface of the laminate 1 prepared in the upper section on which the protective layer B1 was formed and the surface of the aforementioned λ / 4 film on which the λ / 4 layer was formed were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), and then the cellulose acylate film (TG40, manufactured by Fujifilm Corporation), which was the support member for the λ / 4 layer in the obtained laminate, was peeled off between the cellulose acylate film and the photo-alignment film, thereby preparing Optical Film 1.

[0141] (Measurement of Transmittance and Degree of Circular Polarization) The transmittance and degree of circular polarization of the optical film 1 produced in the upper section were measured by measuring the Mueller matrix at a wavelength of 550 nm using an AxoScan OPMF-2 (manufactured by Axometrics). Specifically, using the AxoScan measurement mode "Arbitrary Field-of-View," light was irradiated from the light absorption anisotropic layer side at polar angles of 0°, 30°, and 60°, and at azimuthal angles measured at 5° intervals. The results are shown in Table 1. It was also found that the light incident from a polar angle of 60° was left-handed circularly polarized light.

[0142] [Production of a light guide plate (light guide member) having a liquid crystal diffraction element arranged thereon] A light guide plate (light guide member) having a liquid crystal diffraction element arranged thereon was produced in the same manner as in Comparative Example 5 described in International Publication No. 2021 / 106749. It was confirmed that the produced liquid crystal diffraction element was diffracted when irradiated with right-handed circularly polarized light.

[0143] [Preparation of Optical Element A1] Optical element A1 was prepared by stacking the optical film 1 prepared in the upper section and the light guide element prepared in the upper section. At this time, the optical element A1 was arranged so that, when the optical element A1 was in use, the angle between the slow axis (in-plane slow axis) of the λ / 4 film included in optical element 1 and the horizontal direction was 10°. The layer structure of optical element A1 was, as shown in the table, in the order of "light absorption anisotropic layer 1 / λ / 4 film / light guide element." The optical film 1 was arranged on the side of the light guide element that overlaps with the exit diffraction element (liquid crystal diffraction element) in the planar direction, opposite the light guide plate (in other words, on the side having the exit diffraction element (liquid crystal diffraction element)).

[0144] [Example 2 (Preparation of Optical Element A2)] [Preparation of Optical Film 2] The optical element A2 of Example 2 was prepared according to the following procedure. The optical element A2 corresponds to the second optical element described in the upper section. The surface of the laminate 1 prepared in the upper section on which the protective layer B1 was formed and the surface of the λ / 4 layer of the aforementioned λ / 4 film on which the λ / 4 layer was formed were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). The cellulose acylate film (TG40, manufactured by Fujifilm Corporation), which served as the support member for the λ / 4 layer in the resulting laminate, was then peeled off between the cellulose acylate film and the photoalignment film. Furthermore, the λ / 4 layers of a separately prepared λ / 4 film were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) so that the λ / 4 layers faced each other. The two λ / 4 layers were bonded together so that the angle between their slow axes was 45°. Next, the cellulose acylate film (TG40, manufactured by Fujifilm Corporation), which was a supporting member for the λ / 4 layer, was peeled off between the cellulose acylate film and the photo-alignment film from the λ / 4 film in the obtained laminate, to prepare Optical Film 2. The transmittance and degree of circular polarization were measured in the same manner as described in Example 1. The results are shown in Table 1.

[0145] [Preparation of Optical Element A2] Optical element A2 was prepared by stacking the optical film 2 prepared in the upper section and the light guide element prepared in the upper section. When optical element A2 was in use, the slow axis (in-plane slow axis) of the λ / 4 film on the light guide plate side included in optical film 2 was arranged parallel to the horizontal direction (the angle between the in-plane slow axis and the horizontal direction was 0°). The layer structure of optical element A2 was as shown in the table, in the order of "light absorption anisotropic layer 1 / λ / 4 film / λ / 4 film / light guide element." Furthermore, optical film 2 was arranged on the side of the prepared light guide element opposite the light guide plate (in other words, on the side having the exit diffraction element (liquid crystal diffraction element)) at a position overlapping the exit diffraction element (liquid crystal diffraction element) in the planar direction.

[0146] Example 3 (Preparation of Optical Member A3) An optical member A3 of Example 3 was prepared according to the following procedure: The optical member A3 corresponds to the second optical member described in the upper part.

[0147] [Preparation of λ / 4 Film 2] <Extrusion Molding> 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 extruded film was extruded through a T-die with a width of 1000 mm and a lip gap of 1 mm and cast onto three cast 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 325 μm.

[0148] <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.

[0149] (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: 175°C Stretching temperature: 175°C Stretching ratio: 24% (b) Transverse Stretching The longitudinally stretched film was transversely stretched using a tenter while being transported under the following conditions. -Conditions- Preheating temperature: 180°C Stretching temperature: 180°C Stretching ratio: 140%

[0150] (c) Heat Setting Following the stretching step, the stretched film was heat-set by being held at both ends with tenter clips to maintain a constant width (within a range of expansion or contraction of 3%), and then heat-set under the following conditions: Heat setting temperature: 165°C, Heat setting time: 30 seconds. The preheating temperature, stretching temperature, and heat setting temperature were measured at five points in the width direction using a radiation thermometer and were average values.

[0151] <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 stretched film with a width of 1340 mm and a wound length of 2000 m. The resulting stretched film had an Re of 140 nm and an Rth of 125 nm. The stretched film obtained by the above procedure was designated λ / 4 film 2.

[0152] [Preparation of Optical Film 3] An optical member A3 of Example 3 was prepared according to the following procedure. Optical member A3 corresponds to the second optical member described in the upper section. The surface of the laminate 1 prepared in the upper section on which the protective layer B1 was formed was bonded to the aforementioned λ / 4 film 2 using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). Furthermore, a separately prepared λ / 4 film 2 was bonded to the already bonded λ / 4 film 2 side using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). The two λ / 4 films 2 were bonded so that the angle between the slow axes of the films was 45°, thereby preparing an optical film 3. The transmittance and degree of circular polarization were measured in the same manner as in Example 1. The results are shown in Table 1.

[0153] [Preparation of Optical Member A3] Optical member A3 was prepared in the same manner as optical member A2 in Example 2, except that optical film 2 was changed to optical film 3.

[0154] [Example 4 (Preparation of Optical Member A4)] Optical member A4 of Example 4 was prepared by the following procedure. Note that optical member A4 corresponds to the second optical member described in the upper part. [Preparation of C Plate 1] The following composition for forming C plate 1 was prepared to obtain a uniform solution. ------------------------------------------------ Composition for forming C plate 1------------------------------------------------ 80 parts by mass of discotic liquid crystal compound CA-1 described below 20 parts by mass of discotic liquid crystal compound CA-2 described below 5.6 parts by mass of discotic liquid crystal compound CB-1 described below 5.6 parts by mass of polymerizable monomer CS1 described below 0.2 parts by mass of polymer CC-1 described below 3 parts by mass of polymerization initiator (Irgacure 907, manufactured by BASF) Toluene 170 parts by mass Methyl ethyl ketone 73 parts by mass ------------------------------------------------

[0155] Discotic Liquid Crystal Compound CA-1 (1,3,5-Substituted Benzene-Type Polymerizable Discotic Liquid Crystal Compound)

[0156] Discotic Liquid Crystal Compound CA-2 (1,3,5-Substituted Benzene-Type Polymerizable Discotic Liquid Crystal Compound)

[0157] Discotic liquid crystal compound CB-1 (polymerizable triphenylene-type discotic liquid crystal compound)

[0158] Polymerizable monomer CS1

[0159] Polymer CC-1 (hereinafter, copolymerization ratios in chemical structural formulas are shown in mass %)

[0160] 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 C-plate 1 described above 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 in a drying zone at 100°C for approximately 90 seconds. After that, the temperature was lowered to 60°C, and the film was dried in air 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 Re of the obtained laminated film of the cured film and the support was 3 nm, and the Rth was 180 nm. The above laminated film was designated C-plate 1.

[0161] [Preparation of Optical Film 4] The surface of the laminate 1 prepared in the upper section on which the protective layer B1 was formed and the surface of the aforementioned λ / 4 film on which the λ / 4 layer was formed were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). The cellulose acylate film (TG40, manufactured by Fujifilm Corporation), which was a support member for the λ / 4 layer in the resulting laminate, was peeled off between the cellulose acylate film and the photoalignment film. The peeled surface was then bonded to a C-plate 1 using an adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). Next, the surface of a separately prepared λ / 4 film on which the λ / 4 layer was formed and the already bonded C-plate 1 were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.). The two laminated λ / 4 layers were bonded together such that the angle between the slow axes of the bonded layers was 45°. Next, the cellulose acylate film (TG40, manufactured by Fujifilm Corporation), which was a supporting member for the λ / 4 layer, was peeled off between the cellulose acylate film and the photo-alignment film from the λ / 4 film in the obtained laminate, to prepare Optical Film 4. The transmittance and degree of circular polarization were measured in the same manner as described in Example 1. The results are shown in Table 1.

[0162] [Preparation of Optical Element A4] Optical element A4 was prepared by stacking the optical film 4 prepared in the upper section and the light guide element prepared in the upper section. When optical element A4 was in use, the slow axis (in-plane slow axis) of the λ / 4 film on the light guide plate side included in optical film 4 was parallel to the horizontal direction (the angle between the in-plane slow axis and the horizontal direction was 0°). The layer structure of optical element A4 was as shown in the table, in the order of "light absorption anisotropic layer 1 / λ / 4 film / C plate / λ / 4 film / light guide element." Furthermore, optical film 4 was placed on the side of the prepared light guide element opposite the light guide plate (in other words, on the side having the exit diffraction element (liquid crystal diffraction element)) at a position overlapping the exit diffraction element (liquid crystal diffraction element) in the planar direction.

[0163] [Example 5 (Preparation of Optical Element A5)] Optical element A5 of Example 5 was prepared according to the following procedure. Optical element A5 corresponds to the third optical element described in the upper part. [Preparation of Twist Film 1] A release support was prepared by rubbing the surface of a 75 μm PET film (manufactured by Fujifilm Corporation). Onto the rubbed surface of the prepared release support, the following twist layer coating solution 1 was applied using a bar coater so that the resulting coating film had a thickness of 3.4 μm, forming a coating film. Next, the coating film was heated and aged for 90 seconds at a surface temperature of 60° C., and then irradiated with 300 mJ / cm at 100° C. ２ The orientation of the liquid crystal compound was fixed by irradiating the film with ultraviolet light of 1000 nm to form a twist layer, thereby producing a twist film 1 comprising a peelable support and a twist layer. Analysis using an AxoScan OPMF-2 (manufactured by Axometrics) confirmed that the Δnd of the liquid crystal compound in the resulting twist layer was 550 nm. The twist layer also contained a liquid crystal compound that was twisted and aligned along a helical axis extending along the thickness direction. Analysis using an AxoScan OPMF-2 (manufactured by Axometrics) confirmed that the twist angle of the helical liquid crystal compound was 255°.

[0164] ------------------------------------------------ Coating liquid 1 for twist layer -------------------------------------------------- Methyl ethyl ketone 233 parts by mass Cyclohexanone 12 parts by mass Rod-shaped liquid crystal compound 201 described below 83 parts by mass Rod-shaped liquid crystal compound 202 described below 15 parts by mass Rod-shaped liquid crystal compound 203 described below 2 parts by mass Polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by mass Omnirad 819 (manufactured by IGM Resins B.V.) 4 parts by mass Surfactant 1 described below 0.04 parts by mass Surfactant 2 described below 0.01 parts by mass Chiral agent 1 described below 0.511 parts by mass

[0165]

[0166]

[0167] Chiral agent 1

[0168]

[0169] [Preparation of Optical Film 5] The surface of the laminate 1 prepared in the upper section on which the protective layer B1 was formed was bonded to the surface of the twisted layer of the twisted film 1 described above using a commercially available pressure-sensitive adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), and then the releasable support of the twisted film 1 was peeled off to prepare Optical Film 5. The transmittance and degree of circular polarization were measured in the same manner as described in Example 1. The results are shown in Table 2.

[0170] [Preparation of Optical Element A5] Optical element A5 was prepared by stacking the optical film 5 prepared in the upper section and the light guide element prepared in the upper section. At this time, the optical element A5 was arranged so that, when the optical element A5 was in use, the slow axis (in-plane slow axis) of the twist layer included in the optical film 5 on the light absorption anisotropic layer 1 side formed an angle of 25° with the horizontal direction. The layer structure of optical element A5 was, as shown in the table, in the order of "light absorption anisotropic layer 1 / twist film 1 / light guide element." Furthermore, optical film 5 was arranged on the side of the prepared light guide element opposite the light guide plate (in other words, on the side having the output diffraction element (liquid crystal diffraction element)) at a position overlapping with the output diffraction element (liquid crystal diffraction element) in the planar direction.

[0171] [Example 6 (Preparation of Optical Element A6)] Optical element A6 of Example 6 was prepared according to the following procedure. Optical element A6 corresponds to the third optical element described in the upper section. [Preparation of Twist Film 2] Twist film 2 was prepared in the same manner as twist film 1, except that twist layer coating liquid 1 was replaced with twist layer coating liquid 2 described below. The resulting twist layer had a thickness of 3.1 μm and Δnd of 550 nm. The twist angle of the helical liquid crystal compound in the twist layer was 315°.

[0172] ------------------------------------------------ Twist layer coating liquid 2 -------------------------------------------------- Methyl ethyl ketone 233 parts by mass Cyclohexanone 12 parts by mass Rod-shaped liquid crystal compound 201 83 parts by mass Rod-shaped liquid crystal compound 202 15 parts by mass Rod-shaped liquid crystal compound 203 2 parts by mass Polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by mass Omnirad 819 (manufactured by IGM Resins B.V.) 4 parts by mass Surfactant 1 0.05 parts by mass Surfactant 2 0.01 parts by mass Chiral agent 0.694 parts by mass

[0173] [Preparation of C Plate 2] C Plate 2 was prepared in the same manner as C Plate 1, except that the amount of the composition for forming C Plate 1 was adjusted so that Rth was 200 nm.

[0174] [Preparation of Optical Film 6] The surface of the laminate 1 prepared in the upper section on which the protective layer B1 was formed was bonded to the surface of the twist film 2 on which the twist layer was formed using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), and then the release support of the twist film 2 was peeled off. Next, the release surface and the coated surface of the C-plate 2 were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), thereby preparing Optical Film 6. The transmittance and degree of circular polarization were measured in the same manner as described in Example 1. The results are shown in Table 2.

[0175] [Preparation of Optical Element A6] Optical element A6 was prepared by stacking the optical film 6 prepared in the upper section and the light guide element prepared in the upper section. At this time, when optical element A6 was in use, the slow axis (in-plane slow axis) of the twist layer included in optical film 6 on the light absorption anisotropic layer 1 side formed an angle of 20° with the horizontal direction. The layer structure of optical element A6 was, as shown in the table, in the order of "light absorption anisotropic layer 1 / twist film 2 / C plate 2 / light guide element." Furthermore, optical film 6 was arranged on the side of the prepared light guide element opposite the light guide plate (in other words, on the side having the exit diffraction element (liquid crystal diffraction element)) at a position overlapping with the exit diffraction element (liquid crystal diffraction element) in the planar direction.

[0176] Comparative Example 1 (Preparation of Optical Member B1) Preparation of Optical Film B1 The laminate 1 described above was used as optical film B1. The transmittance and degree of circular polarization were measured in the same manner as in Example 1. The results are shown in Table 3.

[0177] [Preparation of Optical Element B1] The optical element B1 was prepared by stacking the optical film B1 prepared above and the light guide element prepared above. The layer structure of the optical element B1 was as shown in the table, with the order of "light absorption anisotropic layer 1 / light guide element." The optical film B1 was placed on the side of the prepared light guide element opposite the light guide plate, at a position overlapping the exit diffraction element (liquid crystal diffraction element) in the planar direction (i.e., on the side having the exit diffraction element (liquid crystal diffraction element)).

[0178] Comparative Example 2 (Preparation of Optical Element B2) Preparation of Optically Absorbent Anisotropic Layer 2 Laminate 2 was prepared in the same manner as in Laminate 1, except that in the preparation of Optically Absorbent Anisotropic Layer 1, Composition P1 for Forming an Optically Absorbent Anisotropic Layer was changed to Composition P2 for Forming an Optically Absorbent Anisotropic Layer described below, and the coating amount was adjusted so that the coating thickness was 3.2 μm to prepare Optically Absorbent Anisotropic Layer 2. Laminate 2 has a configuration of cellulose acylate film 1 with an alignment film / optically absorptive anisotropic layer 2 / protective layer B1. Hereinafter, the film provided with Optically Absorbent Anisotropic Layer 2 prepared as above will also be referred to as "optically absorptive anisotropic film 2."

[0179] (Measurement of the central transmittance axis of the optically absorbing anisotropic layer 2) The optically absorbing anisotropic film 2 was placed horizontally on a sample stage, and the transmittance was measured using an AxoScan OPMF-2 (manufactured by Axometrics) while varying the azimuthal angle and polar angle of light incident on this film, as described above, to determine the azimuthal angle and polar angle of the central transmittance axis of the optically absorbing anisotropic layer 2. The central transmittance axis of the optically absorbing anisotropic layer 2 was in the direction of a polar angle of 0°.

[0180] ------------------------------------------------ Optically absorptive anisotropic layer forming composition P2---------------------------------------------------------------- Dichroic material D-1 0.69 parts by mass Dichroic material D-2 0.17 parts by mass Dichroic material D-3 1.13 parts by mass Polymer liquid crystal compound P-1 8.67 parts by mass Liquid crystal compound L-1 1.97 parts by mass IRGACURE OXE-02 (manufactured by BASF) 0.20 parts by mass Alignment agent E-1 0.16 parts by mass Alignment agent E-2 0.16 parts by mass Surfactant F-2 0.010 parts by mass Cyclopentanone 78.17 parts by mass Benzyl alcohol 8.69 parts by mass ----------------------------------------------------------------------------------

[0181] [Preparation of Twist Film 3] Twist Film 3 was prepared in the same manner as in the preparation of Twist Film 1, except that Twist Layer Coating Solution 1 was replaced with Twist Layer Coating Solution 3 described below and the amount of coating was adjusted so that the coating thickness was 2.8 μm. The Δnd of the resulting twist layer was 450 nm. The twist angle of the helical liquid crystal compound in the twist layer was 90°.

[0182] ------------------------------------------------ Coating liquid 3 for twist layer -------------------------------------------------- Methyl ethyl ketone 233 parts by mass Cyclohexanone 12 parts by mass Rod-shaped liquid crystal compound 201 83 parts by mass Rod-shaped liquid crystal compound 202 15 parts by mass Rod-shaped liquid crystal compound 203 2 parts by mass Polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by mass IRGACURE 819 (manufactured by BASF) 4 parts by mass Surfactant 1 0.05 parts by mass Surfactant 2 0.01 parts by mass Chiral agent 2 below 0.123 parts by mass --------------------------------------------------

[0183] Chiral agent 2

[0184] [Preparation of Optical Film B2] The surface of the laminate 2 prepared in the upper section on which the protective layer B1 was formed was bonded to the surface of the twisted layer of the twist film 3 described above using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), and then the release support of the twist film 3 was peeled off. Next, the release surface was bonded to the surface of a separately prepared laminate 2 on which the protective layer B1 was formed using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.) to prepare optical film B2. The transmittance and degree of circular polarization were measured in the same manner as described in Example 1. The results are shown in Table 3.

[0185] [Preparation of Optical Element B2] The optical element B2 was prepared by stacking the optical film B2 prepared in the upper section and the light guide element prepared in the upper section. When the optical element B2 was in use, the optical element B2 was arranged so that the slow axis (in-plane slow axis) of the twist layer included in the optical film B2 on the light guide plate side was parallel to the horizontal direction (the angle between the in-plane slow axis and the horizontal direction was 0°). The layer structure of the optical element B2 was in the order of "light absorption anisotropic layer 2 / twist film 3 / light absorption anisotropic layer 2 / light guide element." The optical element B2 was also arranged on the side of the prepared light guide element opposite the light guide plate (in other words, on the side having the exit diffraction element (liquid crystal diffraction element)) at a position overlapping the exit diffraction element (liquid crystal diffraction element) in the planar direction.

[0186] Comparative Example 3 (Preparation of Optical Element B3) 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.

[0187] [Preparation of Optical Film B3] The surface of the polarizing plate on which the polarizer was formed and the surface of the λ / 4 film on which the λ / 4 layer was formed were bonded together using a commercially available adhesive (SK2057, manufactured by Soken Chemical & Engineering Co., Ltd.), and then the cellulose acylate film (TG40, manufactured by Fujifilm Corporation), which served as the support member for the λ / 4 layer in the resulting bonded product, was peeled off between the cellulose acylate film and the photo-alignment film to prepare Optical Film B3. The films were bonded together so that the angle between the absorption axis of the polarizing plate and the slow axis of the λ / 4 film was 45°. The transmittance and degree of circular polarization were measured in the same manner as in Example 1. The results are shown in Table 3.

[0188] [Preparation of Optical Element B3] Optical element B3 was prepared by stacking the optical film B3 prepared in the upper section and the light guide element prepared in the upper section. At this time, when optical element B3 was in use, it was arranged so that the absorption axis of the polarizing plate included in optical element B3 was parallel to the horizontal direction (the angle between the in-plane slow axis and the horizontal direction was 0°). The layer structure of optical element B3 was in the order of "polarizing plate / λ / 4 film / light guide element." Furthermore, optical element B3 was arranged on the side of the prepared light guide element opposite the light guide element (in other words, the side having the exit diffraction element (liquid crystal diffraction element)) at a position overlapping with the exit diffraction element (liquid crystal diffraction element) in the in-plane direction.

[0189] [Evaluation of Optical Members] [Evaluation of Field of View Visibility] The optical members of Examples 1 to 6 and Comparative Examples 1 to 3 were evaluated according to the following procedure. The manufactured optical members were placed in front of the eyes like the lenses of glasses, and evaluated by looking around in all directions, including 360° in the azimuth direction and up and down. Evaluation was performed based on the following criteria, and the results are shown in Tables 1 to 3 below.

[0190] A: No matter where you look in the room, there is no direction in which it is difficult to see what is happening in the room. B: The room light that hits the diffraction element hits your eyes, and there is a direction in which it is slightly difficult to see what is happening in the room. C: The room light that hits the diffraction element hits your eyes, and there is a direction in which it is difficult to see what is happening in the room. D: There is only one direction in which the room light that hits the diffraction element hits your eyes, and it is very difficult to see what is happening in the room. E: There are multiple directions in which the room light that hits the diffraction element hits your eyes, and it is very difficult to see what is happening in the room. In practice, ratings A to D are preferable, with C or higher being more preferable, B or higher being even more preferable, and A being particularly preferable.

[0191] [Evaluation of Visual Field Brightness] The optical members of Examples 1 to 6 and Comparative Examples 1 to 3 were evaluated according to the following procedure. The prepared optical members were placed in front of the eyes like eyeglass lenses, and brightness was evaluated. Evaluation was performed based on the following criteria, and the results are shown in Tables 1 to 3 below.

[0192] A: Compared to when the optical element is not placed in front of the eyes, it feels slightly darker, but it is not bothersome. B: Compared to when the optical element is not placed in front of the eyes, it feels slightly darker in the front direction, but when looking diagonally only in the line of sight, it feels darker and is bothersome. C: Compared to when the optical element is not placed in front of the eyes, it feels darker and is bothersome. In practical terms, an A rating is preferable.

[0193] [Results] The configurations and evaluation results of the optical members of the examples and comparative examples are shown in Tables 1, 2, and 3. Note that light incident from a direction at a polar angle of 60° to the normal direction of each of the optical films (optical films 1 to 6) included in the optical members A1 to A6 was converted into left-handed circularly polarized light.

[0194]

[0195]

[0196]

[0197] From the results in Tables 1 to 3, it is clear that the optical elements of the examples, when used in a head-mounted display in which the background can be seen through AR glasses or the like, provide excellent background brightness and can also suppress visibility problems caused by external light entering from above the head of a user using the head-mounted display.

[0198] 10, 40, 60 Image display device 12, 48, 62 Optical film 14, 42, 64 Polarization control layer 16, 46, 66 Light absorption anisotropic layer 22 Light guide plate 24 Incident diffraction element 26 Outgoing diffraction element 28 Light guide member 30, 50, 68 Optical member 32 Display element 34 Light source 44a First λ / 4 film 44b Second λ / 4 film U User

Claims

1. An optical component comprising: an optical film having a polarization control layer and a light absorbing anisotropic layer; and a light guide plate provided with a diffraction element, the diffraction efficiency of which changes depending on the polarization direction, arranged on the side of the optical film having the polarization control layer, wherein the angle between the central axis of transmittance of the light absorbing anisotropic layer and the normal direction of the light absorbing anisotropic layer is 0 to 45°; the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film; the polarization control layer is a λ / 4 film; and when the optical component is arranged in a usage form, the angle between the slow axis of the λ / 4 film and the horizontal direction is 0 to 20°.

2. An optical component comprising: an optical film having a polarization control layer and a light absorbing anisotropic layer; and a light guide plate provided with a diffraction element, the diffraction efficiency of which changes depending on the polarization direction, arranged on the side of the optical film having the polarization control layer, wherein the angle between the central axis of transmittance of the light absorbing anisotropic layer and the normal direction of the light absorbing anisotropic layer is 0 to 45°; the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film in at least one azimuth angle, a transmittance in the normal direction of the optical film of 55% or more, and a transmittance in a direction that forms an angle of 30° with the normal direction of the optical film of 25% or more; the polarization control layer comprises a first λ / 4 film and a second λ / 4 film, and the angle between the slow axis of the first λ / 4 film and the slow axis of the second λ / 4 film is 30 to 60°.

3. The optical element according to claim 2, wherein the polarization control layer includes the first λ / 4 film, the second λ / 4 film, and a C plate.

4. An optical component comprising: an optical film having a polarization control layer and a light absorbing anisotropic layer; and a light guide plate provided with a diffraction element, the diffraction efficiency of which changes depending on the polarization direction, arranged on the side of the optical film having the polarization control layer, wherein the angle between the central axis of transmittance of the light absorbing anisotropic layer and the normal direction of the light absorbing anisotropic layer is 0 to 45°; the optical film has a degree of circular polarization of 50% or more in a direction that forms an angle of 60° with the normal direction of the optical film, at least in one azimuth angle, a transmittance of 55% or more in the normal direction of the optical film, and a transmittance of 25% or more in a direction that forms an angle of 30° with the normal direction of the optical film; and the polarization control layer is one or more layers containing a liquid crystal compound having a twisted structure.

5. The optical member according to claim 4, wherein the polarization control layer has, from the side where the diffraction element is disposed, one or more layers containing a liquid crystal compound having a twisted structure and a C plate, in that order.

6. AR glasses comprising the optical member according to any one of claims 1 to 5.

Images