Virtual image display device

Abstract

This invention provides a virtual image display device with small deviations in ghost size and stable ghost generation. The virtual image display device includes at least an image display device and a reflex optical system including a reflective circular polarizer. The reflective circular polarizer includes a cholesterol-type liquid crystal layer on the surface of the image display device side. The orientation degree of the liquid crystal compound in the cholesterol-type liquid crystal layer is 0.5 or higher, and the orientation deviation of the liquid crystal compound in the effective area is 30° or less.

Description

Technical Field

[0001] This invention relates to a virtual image display device. Background Technology

[0002] In recent years, virtual image display devices have become increasingly popular as display devices for virtual reality and augmented reality displays. Examples of virtual image display devices include head-mounted displays that include an image display device and lenses. By wearing such a head-mounted display on an observer's head and displaying the image through the lenses, the user can observe a virtual reality-like image with a sense of presence.

[0003] In recent years, to reduce the thickness of head-mounted displays, thin lenses known as pancake lenses have emerged, which reflect light back and forth between a reflective polarizer and a semi-reflective mirror. Depending on their structure, pancake lenses are also called folding optical systems or reflective optical systems. For example, Patent Document 1 discloses a virtual image display device using a folding optical system to miniaturize and thin the display unit.

[0004] Previous technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 7-120679 Summary of the Invention

[0005] The technical problem to be solved by the invention In a virtual image display device using a cookie lens, a portion of the light (image) emitted by the image display device passes through a semi-reflecting mirror and is incident on a reflective polarizer, where it is reflected and refracted back. It then incidents again on the semi-reflecting mirror, where a portion is reflected and refracted back towards the reflective polarizer.

[0006] When reflected by the semi-reflective mirror, the light is converted into light transmitted through the polarizer, and the light transmitted through the polarizer is observed by the user.

[0007] In the biscuit lens described in Patent Document 1, a portion of the light emitted from the image display device fails to travel back and forth between the reflective polarizer and the half-reflector due to polarization disorder and undesirable reflection. Instead, it is transmitted through the reflective polarizer without being reflected when it initially strikes it. This transmitted light is known as light leakage, which can cause problems such as ghosting (double images) and reduced contrast.

[0008] Therefore, the inventors attempted to reduce ghosting by increasing the circular polarization of reflected light through the use of a reflective circular polarizer. As a result, the cookie lens (reflective optical system) including the reflective circular polarizer was effective in reducing ghosting.

[0009] However, according to the research of the inventors, among the pancake lenses made using a reflective circular polarizer, there are individuals with smaller and larger ghosting effects. That is, it has been determined that there is a deviation in the size of the ghosting in the pancake lenses made using a reflective circular polarizer, and resolving this deviation has become a problem.

[0010] The present invention was made in view of the above-mentioned problems. The problem to be solved by the present invention is to provide a virtual image display device that reduces the deviation of ghost size and stably reduces the generation of ghost in a virtual image display device using a reflective optical system.

[0011] means for solving technical problems The inventors conducted in-depth research to solve the aforementioned problems, and as a result, completed this invention. Specifically, they discovered that the aforementioned problems can be solved through the following structure.

[0012] [1] A virtual image display device, comprising at least an image display device and a refracting optical system including a reflective circular polarizer, wherein the reflective circular polarizer includes a cholesterol-type liquid crystal layer, the cholesterol-type liquid crystal layer being on the surface of the image display device, the orientation degree of the liquid crystal compound being 0.5 or more, and the deviation of the azimuth of the liquid crystal compound in the effective area being 30° or less.

[0013] [2] According to the virtual image display device described in [1], the reflective circular polarizer includes a plurality of cholesterol-type liquid crystal layers.

[0014] [3] According to the virtual image display device of [2], the reflective circular polarizer includes at least a cholesterol-type liquid crystal layer formed using a first liquid crystal compound substantially composed of rod-shaped liquid crystal compounds and a cholesterol-type liquid crystal layer formed using a second liquid crystal compound substantially composed of disk-shaped liquid crystal compounds.

[0015] [4] The virtual image display device according to any one of [1] to [3], wherein at least a λ / 4 wave plate and an absorptive linear polarizer are sequentially stacked on the visual recognition side of the reflective circular polarizer.

[0016] [5] The virtual image display device according to any one of [1] to [4], wherein the reflective circular polarizer is formed in a curved shape.

[0017] Invention Effects According to the present invention, in a virtual image display device using a reflective optical system, it is possible to provide a virtual image display device with small deviation in ghost size and stable ghost generation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an example of the virtual image display device of the present invention.

[0019] Figure 2 This is a schematic diagram illustrating an example of the virtual image display device of the present invention.

[0020] Figure 3 This is a schematic diagram illustrating an example of the virtual image display device of the present invention.

[0021] Figure 4 This is a Poincaré sphere diagram showing the change in polarization state of light transmitted and reflected by the circular polarizer in the virtual image display device of the present invention.

[0022] Figure 5 This is a Poincaré sphere diagram showing the change in polarization state of light transmitted and reflected from the circular polarizer in the virtual image display device of the present invention.

[0023] Figure 6 This is a Poincaré sphere diagram showing the change in polarization state of light transmitted and reflected from the circular polarizer in the virtual image display device of the present invention.

[0024] Figure 7 This is a Poincaré sphere diagram showing the change in polarization state of light transmitted and reflected from the circular polarizer in the virtual image display device of the present invention. Detailed Implementation

[0025] The virtual image display device of the present invention will now be described in detail.

[0026] The following description of the constituent elements is sometimes based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0027] In addition, in this specification, the numerical range indicated by “~” refers to the range included by taking the values ​​recorded before and after “~” as the lower limit and upper limit values.

[0028] In this specification, "orthogonal" is defined as not indicating that the angle between two axes is strictly 90°, but rather 90° ± 10°, preferably 90° ± 5°. Furthermore, "parallel" is defined as indicating that the angle between two axes is 0° ± 10° (preferably 0° ± 5°), rather than 0° in the strict sense.

[0029] Furthermore, "45°" is set to mean that the angle between two axes is 45°±10° (preferably 45°±5°), rather than 45° in the strict sense.

[0030] In this specification, "absorption axis" refers to the polarization direction in which the in-plane absorbance is maximized when incident linearly polarized light. "Reflection axis" refers to the polarization direction in which the in-plane reflectivity is maximized when linearly polarized light is incident. "Transmission axis" refers to the direction in-plane orthogonal to either the absorption or reflection axis. Furthermore, "slow axis" refers to the direction in-plane where the refractive index is maximized. "Fast axis" refers to the direction in-plane where the refractive index is minimized, and is orthogonal to the slow axis.

[0031] In this specification, unless otherwise specified, phase difference refers to in-plane delay, denoted as Re(λ). Here, Re(λ) represents the in-plane delay at wavelength λ, which is set to 550 nm unless otherwise specified.

[0032] Furthermore, the thickness-direction delay at wavelength λ is described in this specification as Rth(λ). Unless otherwise specified, wavelength λ is set to 550 nm.

[0033] Re(λ) and Rth(λ) can be obtained using an AxoScan OPMF-1 (manufactured by Opto Science, Inc.) at wavelength λ. The following values ​​are calculated by inputting the average refractive index ((nx+ny+nz) / 3) and film thickness (d(μm)) into AxoScan: Slow axis direction (°) Re(λ) = R0(λ) Rth(λ)=((nx+ny) / 2-nz)×d.

[0034] <Virtual Image Display Device> The virtual image display device of the present invention has at least an image display device and a folding optical system including a reflective circular polarizer.

[0035] Furthermore, the reflective circular polarizer includes a cholesterol-type liquid crystal layer. Moreover, on the surface of the cholesterol-type liquid crystal layer on the image display device side, the orientation degree of the liquid crystal compound is 0.5 or higher, and the deviation of the director azimuth of the liquid crystal compound within the effective area is 30° or less.

[0036] use Figure 1 The structure for generating virtual images by the virtual image display device of the present invention will be described.

[0037] Figure 1 This is a diagram that conceptually illustrates an example of the virtual image display device of the present invention.

[0038] Figure 1The virtual image display device 1000 shown includes an image display device 500 and a reflective optical system 600. In the virtual image display device 1000 of the present invention, the reflective optical system 600 includes a reflective circular polarizer 200. Furthermore, in addition to the reflective circular polarizer 200, the reflective optical system 600 of the example figure also includes a semi-reflective mirror 300.

[0039] The reflective circular polarizer 200 includes a cholesterol-type liquid crystal layer. As an example, this reflective circular polarizer 200, specifically the cholesterol-type liquid crystal layer, reflects right-handed circularly polarized light and transmits left-handed circularly polarized light. Furthermore, on the surface of the cholesterol-type liquid crystal layer on the image display device 500 side, the orientation degree of the liquid crystal compound is 0.5 or more, and the deviation of the director azimuth of the liquid crystal compound within the effective area is 30° or less.

[0040] The light 10 (image) emitted by the image display device 500 is circularly polarized light. In the example shown, the image display device 500 emits right-handed circularly polarized light.

[0041] As an example, the image display device 500 sequentially includes an image display element (display panel), a phase retardation layer (λ / 4 waveplate), a linear polarizer, and another phase retardation layer (λ / 4 waveplate). In this image display device 500, light (unpolarized light) emitted from the image display element passes through the phase retardation layer, becomes linearly polarized light through the linear polarizer, is converted into right-hand circularly polarized light by the phase retardation layer, and is emitted as light ray 10. Furthermore, the phase retardation layer directly downstream of the image display element, together with the linear polarizer, constitutes the anti-reflective film of the image display element.

[0042] A portion of the light 10 (right-hand circularly polarized light) emitted from the image display device 500 is transmitted through the semi-reflective mirror 300 and then incident on the reflective circular polarizer 200.

[0043] As described above, the reflective circular polarizer 200 has a cholesterol-type liquid crystal layer that selectively reflects right-handed circularly polarized light. Therefore, the right-handed circularly polarized light 10 incident on the reflective circular polarizer 200 is reflected back into the optical path by the reflective circular polarizer 200 and is incident on the half-reflector 300 again, where a portion is reflected by the half-reflector 300.

[0044] During this reflection, light 10 is converted into left-handed circularly polarized light and re-enters the reflective circular polarizer 200. As described above, the reflective circular polarizer 200 is a cholesterol-type liquid crystal layer that selectively reflects right-handed circularly polarized light, and light 10 is converted into left-handed circularly polarized light. Therefore, light 10 is transmitted through the reflective circular polarizer 200.

[0045] Thus, a portion of the light ray 10 is reflected within the refraction optical system 600.

[0046] Here, Figure 1The refracting optical system 600 shown functions as a concave mirror when reflecting light ray 10 because the semi-reflecting mirror 300 is curved. Furthermore, the refracting optical system 600 sometimes produces lens power by refracting light ray 10 according to its shape.

[0047] Through these actions, the light rays 10 emitted from the image display device 500 are roughly parallelized and reach the user's eyes, enabling the user to visually recognize the image displayed on the image display device as a virtual image.

[0048] Furthermore, in the above example, the reflective circular polarizer 200 reflects right-handed circularly polarized light and transmits left-handed circularly polarized light, but the present invention is not limited thereto. That is, the reflective circular polarizer 200 can also reflect left-handed circularly polarized light and transmit right-handed circularly polarized light. In this case, an image display device that emits left-handed circularly polarized light can be used, and the effects of the present invention will not be diminished.

[0049] The same applies to the points mentioned above in the following explanation.

[0050] <The principle behind ghosting> Next, use Figure 2 The conceptual diagram illustrates the principle of ghosting in the virtual image display device 1000.

[0051] As described above, in the virtual image display device 1000, a portion of the light 10 emitted from the image display device 500 passes through the semi-reflective mirror 300 and enters the reflective circular polarizer 200, and is reflected by the reflective circular polarizer 200.

[0052] However, as Figure 2 As schematically shown, a portion of the light ray 10 emitted from the image display device 500 passes through the semi-reflective mirror 300 and is not reflected by the reflective circular polarizer 200, but is instead transmitted through the reflective circular polarizer 200. Hereinafter, this portion of the light ray 10 is designated as light ray 11. This light ray 11 is not substantially parallelized and reaches the user's eye with a different optical path length than light ray 10. Therefore, it is perceived by the user as an image different from the virtual image perceived by the user, that is, it is perceived as a ghost image.

[0053] <The principle behind the deviation in ghost size> exist Figure 1 and Figure 2 In order to simplify the illustrations, they have been omitted, but as... Figure 3 As shown, the virtual image display device 1000 of the present invention preferably includes an absorption-type circular polarizer 400.

[0054] In the example shown, the light 10 emitted from the image display device 500 is right-handed circularly polarized light. Therefore, when it is initially incident on the reflective circular polarizer 200, most of the light 11 that is unnecessarily transmitted through the reflective circular polarizer 200 is right-handed circularly polarized light.

[0055] Therefore, as Figure 3 Conceptually, by stacking an absorptive circular polarizer 400 that absorbs right-handed circularly polarized light on the visual recognition side (user side) of the reflective circular polarizer 200, ghosting can be significantly reduced. Furthermore, as an example, the absorptive circular polarizer 400 can be fabricated by stacking a λ / 4 waveplate (λ / 4 phase difference layer) 401 and an absorptive linear polarizer 402. Moreover, the absorptive circular polarizer 400 transmits left-handed circularly polarized light, thus having almost no impact on the display quality of the virtual image perceived by the user.

[0056] On the other hand, it is also known that after the transmission-reflection circular polarizer 200, a portion of the ray 11 is sometimes converted into left-handed circularly polarized light. Additionally, in Figure 3 In order to distinguish it from the light 11, which is mainly right-handed circularly polarized light, the light ray that converts right-handed circularly polarized light 11 into left-handed circularly polarized light is designated as light ray 12.

[0057] According to the researchers' findings, the light intensity of ray 12 deviates significantly. It is speculated that this deviation in light intensity is the cause of the deviation in ghosting size in virtual image display devices using a reflex optical system.

[0058] Since light ray 12 is left-handed circularly polarized, it cannot be absorbed by the absorptive circular polarizer 400, which absorbs right-handed circularly polarized light. Therefore, it is difficult to suppress the ghosting deviation caused by light ray 12 (left-handed circularly polarized light) with a large deviation in light quantity.

[0059] The inventors speculate on the mechanism by which a portion of the light ray 11 is converted into left-handed circularly polarized light (light ray 12) by the reflected circular polarizer 200 as follows.

[0060] Figure 4 This is a diagram that conceptually represents the change in polarization state of light 11 incident on the reflecting circular polarizer 200 as it passes through the reflecting circular polarizer 200, using a Poincaré sphere.

[0061] Ray 11 is right-handed circularly polarized when incident on the reflecting circular polarizer 200. Therefore, in the Poincaré sphere, this represents the position at point S3 (the top of the S3 axis).

[0062] Furthermore, the reflecting circular polarizer 200 selectively reflects right-handed circularly polarized light. Therefore, as the light ray 11, primarily right-handed circularly polarized light, travels within the reflecting circular polarizer 200, the amount of transmitted light decreases. In this specification, the amount of light is expressed as the distance from the center of the Poincaré sphere. That is, in this specification, the decrease in the amount of transmitted light within the Poincaré sphere, such as... Figure 4 As shown, the trajectory representing the change in polarization state spirals near the S3 axis while moving towards the center of the Poincaré sphere.

[0063] Figure 5 Viewed from point S3 (S3 axis) Figure 4 A picture of the Poincaré ball.

[0064] exist Figure 5 From this, we can see that the trajectory representing the change in polarization state is generally biased towards the first quadrant and depicts a spiral. Figure 5 In the diagram, the first quadrant is the quadrant formed by the S1 and S2 axes. The trajectory indicating the change in polarization state moving away from the S3 axis means that a portion of ray 11 is converted into left-handed circularly polarized light, i.e., ray 12.

[0065] The polarization state of light ray 11 changes due to the optical effect of the liquid crystal compound contained in the cholesteric liquid crystal layer constituting the reflective circular polarizer 200. Here, according to the research of the present inventors, the direction in which the trajectory representing the change in polarization state initially moves on the Poincaré sphere is determined by the direction of the director of the liquid crystal compound on the light incident surface side of the cholesteric liquid crystal layer.

[0066] therefore, Figure 5 The polarization direction is roughly determined by the orientation of the liquid crystal compound on the light incident side of the cholesterol-type liquid crystal layer.

[0067] However, the orientation of the director of the liquid crystal compound in a cholesterol-type liquid crystal layer can be various, so the polarization of the polarization state on the Poincaré sphere is not constant, which is speculated to be the reason for the deviation in the size of the ghosting.

[0068] On the other hand, the light 10 emitted from the image display device 500 is not strictly circularly polarized light, but typically elliptically polarized light. In this case, if the polarization state of the light 11 before it enters the reflecting circular polarizer 200 is represented on a Poincaré sphere, then as... Figure 6 and Figure 7 Point A is shown, indicating a position slightly separated from the S3 axis (point S3).

[0069] like Figure 6 As shown, on the Poincaré sphere, if the polarization of the trajectory based on the change in polarization state of the cholesterol-type liquid crystal layer is in the direction that cancels the polarization of ray 11, then the proportion of ray 11 converted into left-handed circularly polarized light is small, and the ghosting is also reduced. On the other hand, as Figure 7 As shown, if the polarization of the trajectory of the change in polarization state is the orientation of increasing the polarization of light 11, then the proportion of light 11 converted into left-handed circularly polarized light is large, resulting in a larger ghosting.

[0070] That is, ghosting can be reduced by adjusting the polarization of the trajectory of the light ray 10 based on the polarization state of the cholesterol-type liquid crystal layer. Alternatively, ghosting can be reduced by adjusting the polarization state of the light ray 10 based on the polarization of the trajectory of the light ray 10 based on the polarization state of the cholesterol-type liquid crystal layer.

[0071] For example, as described above, the polarization direction of the trajectory based on the change in the polarization state of the cholesterol-type liquid crystal layer is approximately determined by the director orientation of the liquid crystal compound on the light incident surface side of the cholesterol-type liquid crystal layer. Therefore, by adjusting the director orientation of the liquid crystal compound on the light incident surface side of the cholesterol-type liquid crystal layer according to the polarization state of the light ray 10, ghosting can be reduced.

[0072] Furthermore, in this invention, the deviation in the size of the ghost image has two specific meanings.

[0073] The first deviation in ghost size refers to the deviation in ghost size of each individual component in the cholesterol-type liquid crystal layer (reflective circular polarizer), i.e., the virtual image display device. In other words, this deviation in ghost size refers to the individual differences among multiple components and devices.

[0074] The second deviation in ghost size refers to the deviation in the size of the ghost image within the plane of a cholesterol-type liquid crystal layer (reflective circular polarizer), i.e., in the displayed image based on a virtual image display device. That is, this deviation in ghost size refers, for example, to a smaller ghost image in the center of the displayed virtual image in the vertical direction, and a larger ghost image in the upper and lower parts.

[0075] <Virtual Image Display Device of the Invention> Based on the above speculation, the inventors deduced that by controlling the orientation of the liquid crystal compound on the light incident surface side of the cholesterol-type liquid crystal layer to a constant orientation, the deviation in the size of ghosting in the virtual image display device can be reduced, thus completing the present invention.

[0076] That is, as described above, the generation of left-handed circularly polarized light, which causes ghosting, is due to a change in the polarization state of right-handed circularly polarized light, i.e., ray 11, transmitted through the cholesterol-type liquid crystal layer. Furthermore, the initial direction of the trajectory representing the change in polarization state on the Poincaré sphere is determined by the directionality of the director of the liquid crystal compound on the light-incident side of the cholesterol-type liquid crystal layer. Therefore, Figure 5 The polarization direction of the polarized light in the image is roughly determined by the orientation of the liquid crystal compound on the light incident surface side of the cholesterol-type liquid crystal layer. Deviations in this orientation cause deviations in the size of the ghosting.

[0077] Therefore, if the orientation of the liquid crystal compound on the light incident surface side of the cholesterol-type liquid crystal layer is not deviated, the change in polarization state of the circularly polarized light (elliptical polarized light) of the transmission and reflection circular polarizer 200 can be homogenized, thereby reducing the deviation of ghosting.

[0078] The virtual image display device of the present invention includes at least an image display device and a reflex optical system including a reflective circular polarizer. The reflective circular polarizer includes a cholesterol-type liquid crystal layer. On the surface of the cholesterol-type liquid crystal layer on the side of the image display device, i.e. the surface on which the light ray 10 (light ray 11) is incident, the orientation degree of the liquid crystal compound is 0.5 or more, and the deviation of the azimuth of the liquid crystal compound in the effective area is 30° or less.

[0079] The virtual image display device of the present invention, by having this structure, can reduce the deviation in the size of ghosting in the virtual image display device.

[0080] In addition, the effective area refers to the area in the in-plane region of the reflective circular polarizer assembled in the virtual image display device that transmits light from the image display device when the user visually recognizes the displayed virtual image.

[0081] In the virtual image display device of the present invention, if the orientation degree of the liquid crystal compound of the cholesterol-type liquid crystal layer on the surface of the image display device is less than 0.5, the ghosting deviation cannot be sufficiently reduced, and the circularly polarized light (e.g., right-handed circularly polarized light) that should be reflected cannot be sufficiently reflected, thereby causing adverse conditions such as increased ghosting.

[0082] The orientation degree of the liquid crystal compound in the cholesterol-type liquid crystal layer on the side of the image display device is preferably 0.6 or more, and more preferably 0.65 or more.

[0083] In this invention, the higher the orientation degree of the liquid crystal compound in the cholesterol-type liquid crystal layer on the surface of the image display device, the better, with the upper limit of 1 being the most preferred.

[0084] In the virtual image display device of the present invention, if the orientation deviation of the liquid crystal compound in the effective area of ​​the cholesterol-type liquid crystal layer on the surface of the image display device exceeds 30°, an undesirable situation arises in which the deviation cannot be sufficiently reduced.

[0085] The orientation deviation of the liquid crystal compound in the effective area of ​​the cholesterol-type liquid crystal layer on the side of the image display device is preferably 10° or less, more preferably 5° or less.

[0086] Furthermore, in this invention, it is preferred that the orientation deviation of the liquid crystal compound in the effective area of ​​the cholesterol-type liquid crystal layer on the surface of the image display device is as small as possible, and most preferably 0°.

[0087] Furthermore, according to the research of the present inventors, when the cholesteric liquid crystal layer on the image display device side of the reflective circular polarizer is a layer composed of rod-shaped liquid crystal compounds, the orientation of the polarization axis of the elliptically polarized light emitted by the image display device at a wavelength of 550 nm is preferably at an angle of 45 to 90° with the orientation of the director of the liquid crystal compound on the image display device side of the cholesteric liquid crystal layer, and more preferably at an angle of 55 to 80°.

[0088] Furthermore, when the cholesterol-type liquid crystal layer on the image display device side of the reflective circular polarizer is a layer composed of a disk-shaped liquid crystal compound, the orientation of the polarization axis of the elliptically polarized light emitted by the image display device at a wavelength of 550 nm is preferably at an angle of 0 to 45° with the orientation of the director of the liquid crystal compound on the image display device side of the cholesterol-type liquid crystal layer, and more preferably at an angle of 10 to 35°.

[0089] If the angle is within the above range, the position in the Poincaré sphere of the elliptically polarized light becomes the position to counteract the deviation in polarization state caused by the cholesterol-type liquid crystal layer, thus minimizing ghosting.

[0090] Furthermore, the average ellipticity of the elliptically polarized light emitted by the image display device at wavelengths of 450–650 nm is preferably 0.8–0.99. If the ellipticity is within this range, ghosting can be further reduced, which is therefore preferable. The average ellipticity is more preferably 0.85–0.98, and even more preferably 0.93–0.98.

[0091] Furthermore, the orientation of the elliptical axis of elliptically polarized light indicates the orientation of the major axis of the ellipse in the elliptical orbit depicted by the change in the electric field in the elliptically polarized light. And the ellipticity represents the ratio of the length of the major axis to the length of the minor axis in the elliptical orbit.

[0092] The orientation of the elliptic axis and the ellipticity of the ellipsoidally polarized light emitted by the image display device can be obtained, for example, by peeling the circular polarizer off the surface of the image display device and measuring it at a wavelength of 550 nm using an AxoScan OPMF-1 (manufactured by Opto Science, Inc.).

[0093] <Reflective Circular Polarizer> A reflective circular polarizer is a polarizer that transmits right-handed or left-handed circularly polarized light and reflects circularly polarized light with a direction of rotation opposite to that of the transmitted circularly polarized light.

[0094] The reflective circular polarizer included in the virtual image display device of the present invention has a cholesterol-type liquid crystal layer. The cholesterol-type liquid crystal layer is a liquid crystal phase formed by fixing a cholesterol-oriented liquid crystal phase (cholesterol-type liquid crystal phase).

[0095] As is well known, cholesterol-type liquid crystal layers have a helical structure in which liquid crystal compounds rotate in a spiral and are stacked. The structure formed by rotating (360°) the liquid crystal compounds in a spiral and stacking them is defined as one spiral cycle (spiral cycle (spiral pitch)). Liquid crystal compounds rotating in a spiral have a structure formed by stacking multiple cycles.

[0096] Cholesterol-type liquid crystal layers reflect right-handed or left-handed circularly polarized light in specific wavelength regions, depending on the length of the spiral period and the rotation direction (helix direction) of the spiral generated by the liquid crystal compound, while allowing other light to pass through.

[0097] Therefore, when a virtual reality display device displays a color image, the reflective circular polarizer may have, for example, multiple cholesteric liquid crystal layers, such as a cholesteric liquid crystal layer with a center wavelength that selectively reflects red light, a cholesteric liquid crystal layer with a center wavelength that selectively reflects green light, and a cholesteric liquid crystal layer with a center wavelength that selectively reflects blue light.

[0098] Furthermore, in addition to the cholesterol-type liquid crystal layer, the reflective circular polarizer may also have a support and an alignment film for orienting the liquid crystal compounds in the cholesterol-type liquid crystal layer.

[0099] In the virtual image display device of the present invention, the reflective circular polarizer included in the reflex optical system comprises a cholesterol-type liquid crystal layer. On the surface of this cholesterol-type liquid crystal layer on the image display device side, the orientation degree of the liquid crystal compound is 0.5 or more, and the deviation of the director azimuth of the liquid crystal compound within the effective area is 30° or less.

[0100] On the image display device side of the cholesterol-type liquid crystal layer, the aforementioned deviations in orientation and direction of the pointing vector can be achieved by performing an orientation process in which the orientation direction of the liquid crystal compound is aligned in one direction during the formation of the cholesterol-type liquid crystal layer.

[0101] The alignment process can be performed, for example, as follows: A photoalignment film is coated onto a support, and the photoalignment film is irradiated with polarized ultraviolet light, etc. Then, a liquid crystal composition containing a liquid crystal compound is coated, aligning the liquid crystal compound to a cholesterol-type liquid crystal phase. Finally, the liquid crystal compound is cured to form a cholesterol-type liquid crystal layer that fixes the cholesterol-type liquid crystal phase. The orientation of the liquid crystal compound can be controlled by the orientation of the polarization axis of the polarized light irradiating the photoalignment film. Furthermore, the alignment process can also be performed by rubbing the support or the alignment film coated on the support.

[0102] The alignment treatment surface of the cholesterol-type liquid crystal layer thus formed, i.e., the alignment film side, is set as the image display device side, i.e., the incident side of light 10 (light 11). Therefore, on the image display device side surface of the cholesterol-type liquid crystal layer, the alignment degree of the liquid crystal compound can be set to 0.5 or more, and the deviation of the director orientation of the liquid crystal compound in the effective area can be set to 30° or less.

[0103] In addition, the orientation degree and director orientation of the liquid crystal compounds on the surface of the cholesterol-type liquid crystal layer can be measured by methods such as SHG (Second Harmonic Generation).

[0104] Here, orientation degree refers to an index representing the local order of a liquid crystal compound, also known as the order parameter. Regarding orientation degree, SHG measurements are performed at 5 locations within the effective area when the reflective circular polarizer is assembled into the virtual image display device, and all values ​​are acceptable as long as they are greater than 0.5.

[0105] Furthermore, the azimuth direction indicates the principal axis direction of the liquid crystal compound. The deviation of the azimuth direction of the liquid crystal compound within the effective area refers to the maximum value of the angle between the azimuth directions at different locations within the effective area when the reflective circular polarizer is assembled in the virtual image display device, after SHG measurements are performed at 5 locations and the local azimuth direction is measured.

[0106] Specifically, a photo-alignment film is an alignment film containing a photo-alignment material.

[0107] Examples of photoalignment materials included in photoalignment films include Japanese Patent Application Publication Nos. 2006-285197, 2007-76839, 2007-138138, 2007-94071, 2007-121721, 2007-140465, and 2007-156439. Azo compounds described in Japanese Patent Application Publication No. 2007-133184, Japanese Patent Application Publication No. 2009-109831, Japanese Patent No. 3883848, Japanese Patent No. 4151746, aromatic ester compounds described in Japanese Patent Application Publication No. 2002-229039, Japanese Patent Application Publication No. 2002-265541, and Japanese Patent Application Publication No. 2002-317013. The following are described: maleimide and / or alkenyl-substituted nadicimide compounds having photooriented units; photocrosslinking silane derivatives described in Japanese Patent Nos. 4205195 and 4205198; Japanese Patent Publication Nos. 2003-520878, 2004-529220, and Japanese Patent No. 4162850, which describe photocrosslinking polyimides, polyamides, or esters; and Japanese... Compounds capable of photodimerization, particularly cinnamic acid ester compounds, chalcone compounds, and coumarin compounds, as described in Japanese Patent Application Publication No. 9-118717, Japanese Patent Application Publication No. 10-506420, Japanese Patent Application Publication No. 2003-505561, International Publication No. 2010 / 150748, Japanese Patent Application Publication No. 2013-177561, and Japanese Patent Application Publication No. 2014-12823, are preferred examples of photo-aligning materials. Examples include azo compounds, photocrosslinkable polyimides, polyamides, esters, cinnamic acid ester compounds, and chalcone compounds.

[0108] A photoalignment film can be formed by coating a composition containing the aforementioned photoalignment material, and then irradiating the coating film with light to impart an alignment constraint force. Furthermore, the irradiation is preferably polarized light irradiated from a direction perpendicular to the surface of the coating film or from a direction inclined to the perpendicular direction. Alternatively, the irradiation can also be unpolarized light irradiated from a direction inclined to the perpendicular direction of the coating film.

[0109] In addition, compositions containing the aforementioned photoalignment materials may contain components other than photoalignment materials capable of forming photoalignment films.

[0110] The refractive index of the photoalignment film can be adjusted according to the type of photoalignment material mentioned above. Furthermore, the refractive index of the photoalignment film can also be adjusted by other components contained together with the photoalignment material.

[0111] In addition, the photoalignment film is a layer with liquid crystal alignment capability. Specifically, liquid crystal alignment capability refers to the ability to impart alignment to liquid crystal compounds.

[0112] (Method for forming a cholesterol-type liquid crystal layer) Cholesterol-type liquid crystal layers can be formed by layering and fixing the cholesterol-type liquid crystal phase.

[0113] The structure formed by fixing the cholesterol-type liquid crystal phase can be any structure in which the orientation of the liquid crystal compound that is a cholesterol-type liquid crystal phase is maintained. Typically, the following structure is preferred: on the basis of making the polymerizable liquid crystal compound into a cholesterol-type liquid crystal phase orientation state, it is polymerized and cured by ultraviolet irradiation, heating, etc. to form a non-flowing layer, and at the same time becomes a state in which the orientation morphology will not change due to external field or external force.

[0114] Furthermore, in structures formed by fixing a cholesterol-type liquid crystal phase, it is sufficient to maintain the optical properties of the cholesterol-type liquid crystal phase; in a cholesterol-type liquid crystal layer, the liquid crystal compound may not exhibit liquid crystal properties. For example, polymeric liquid crystal compounds, through a curing reaction, become high molecular weight and can lose their liquid crystal properties.

[0115] As an example of materials used in the formation of a cholesterol-type liquid crystal layer formed by fixing a cholesterol-type liquid crystal phase, a liquid crystal composition comprising a liquid crystal compound can be cited. The liquid crystal compound is preferably a polymerizable liquid crystal compound.

[0116] Furthermore, the liquid crystal composition used in the formation of the cholesterol-type liquid crystal layer may also contain surfactants and chiral reagents.

[0117] --Polymerizable liquid crystal compounds-- Polymerizable liquid crystal compounds can be rod-shaped or disc-shaped.

[0118] Examples of rod-shaped polymerizable liquid crystal compounds that form cholesterol-type liquid crystal phases include rod-shaped nematic liquid crystal compounds. Preferred rod-shaped nematic liquid crystal compounds include imine derivatives, azo derivatives, cyanobiphenyl derivatives, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane derivatives, cyano-substituted phenylpyrimidine derivatives, alkoxy-substituted phenylpyrimidine derivatives, phenyl dioxane derivatives, diphenylacetylene derivatives, and alkenylcyclohexylbenzonitrile derivatives. Not only low-molecular-weight liquid crystal compounds but also high-molecular-weight liquid crystal compounds can be used.

[0119] Polymerizable liquid crystal compounds can be obtained by introducing polymerizable groups into a liquid crystal compound. Examples of polymerizable groups include unsaturated polymerizable groups, epoxy groups, and aziridinyl groups, preferably unsaturated polymerizable groups, and more preferably olefinic unsaturated polymerizable groups. Polymerizable groups can be introduced into the molecules of the liquid crystal compound by various methods. The number of polymerizable groups in the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3.

[0120] Examples of polymerizable liquid crystal compounds include those described in Makromol. Chem., Vol. 190, pp. 2255 (1989), Advanced Materials, Vol. 5, pp. 107 (1993), U.S. Patent No. 4,683,327, U.S. Patent No. 5,622,648, U.S. Patent No. 5,770,107, International Publications Nos. 95 / 22586, 95 / 24455, 97 / 00600, 98 / 23580, 98 / 52905, Japanese Patent Application Publications Nos. 1-272,551, 6-016,616, 7-110,469, 11-080081, and 2001-328,973. Two or more polymerizable liquid crystal compounds can be used together. Using two or more polymerizable liquid crystal compounds together can lower the orientation temperature.

[0121] Furthermore, as polymeric liquid crystal compounds other than those mentioned above, cyclic organopolysiloxane compounds having a cholesterol phase as disclosed in Japanese Patent Application Publication No. 57-165480 can be used. Moreover, as the aforementioned polymeric liquid crystal compounds, polymers with mesocrystalline groups for displaying liquid crystals incorporated into the main chain, side chain, or both the main chain and side chain, cholesteric liquid crystals with cholesterol groups incorporated into the side chains, liquid crystal polymers as disclosed in Japanese Patent Application Publication No. 9-133810, and liquid crystal polymers as disclosed in Japanese Patent Application Publication No. 11-293252 can be used.

[0122] --Disc-shaped liquid crystal compound-- As a disc-shaped liquid crystal compound, the disc-shaped liquid crystal compound described in Japanese Patent Application Publication No. 2007-108732 and Japanese Patent Application Publication No. 2010-244038 are preferred, for example.

[0123] From the viewpoint of improving the reflectivity of circularly polarized light from the reflective circular polarizer and reducing ghosting, the reflective circular polarizer preferably includes at least a cholesterol-type liquid crystal layer formed using a first liquid crystal compound substantially composed of rod-shaped liquid crystal compounds and a cholesterol-type liquid crystal layer formed using a second liquid crystal compound substantially composed of disk-shaped liquid crystal compounds.

[0124] The phrase "substantially composed of rod-shaped liquid crystal compounds" means that the rod-shaped liquid crystal compounds constitute 95% or more of the liquid crystal compounds in the cholesterol-type liquid crystal layer. The phrase "substantially composed of disc-shaped liquid crystal compounds" means that the disc-shaped liquid crystal compounds constitute 95% or more of the liquid crystal compounds in the cholesterol-type liquid crystal layer.

[0125] Furthermore, the amount of polymerizable liquid crystal compound added in the liquid crystal composition is preferably 75 to 99.9% by mass relative to the mass of the solid components of the liquid crystal composition (mass after removing the solvent), more preferably 80 to 99% by mass, and even more preferably 85 to 90% by mass.

[0126] --surfactants-- The liquid crystal composition used to form a cholesterol-type liquid crystal layer may contain a surfactant.

[0127] The surfactant is preferably a compound capable of functioning as an orientation control agent, which helps to stably or rapidly orient the cholesterol-type liquid crystal phase. Examples of surfactants include silicone-based surfactants and fluorinated surfactants, with fluorinated surfactants being preferred.

[0128] Specific examples of surfactants include compounds described in paragraphs

[0082] to

[0090] of Japanese Patent Application Publication No. 2014-119605, compounds described in paragraphs

[0031] to

[0034] of Japanese Patent Application Publication No. 2012-203237, compounds exemplified in paragraphs

[0092] and

[0093] of Japanese Patent Application Publication No. 2005-099248, compounds exemplified in paragraphs

[0076] to

[0078] and

[0082] to

[0085] of Japanese Patent Application Publication No. 2002-129162, and fluoro(meth)acrylate polymers described in paragraphs

[0018] to

[0043] of Japanese Patent Application Publication No. 2007-272185.

[0129] In addition, a single surfactant can be used alone, or two or more surfactants can be used in combination.

[0130] As a fluorinated surfactant, the preferred choice is the compound described in paragraphs

[0082] to

[0090] of Japanese Patent Application Publication No. 2014-119605.

[0131] The amount of surfactant added to the liquid crystal composition is preferably 0.01 to 10% by mass relative to the total mass of the liquid crystal compound, more preferably 0.01 to 5% by mass, and even more preferably 0.02 to 1% by mass.

[0132] --Chiral reagents (optically active compounds)-- Chiral agents have the ability to twist the helical structure of cholesterol-type liquid crystal phases. Since the direction of helical twisting or the helical period induced by the compound varies, the chiral agent can be selected based on the intended purpose.

[0133] There are no particular restrictions on the use of chiral reagents, and well-known compounds can be used (e.g., described in Liquid Crystal Devices Handbook, Chapter 3, Item 4-3, TN (twisted nematic), STN (Super Twisted Nematic) chiral reagents, page 199, edited by Committee 142 of the Japan Society for the Promotion of Science, described in 1989), isosorbide and isomannitol derivatives, etc.

[0134] Chiral reagents typically contain asymmetric carbon atoms, but axially chiral compounds or planar chiral compounds that do not contain asymmetric carbon atoms can also be used as chiral reagents. Examples of axially asymmetric or surface-asymmetric compounds include binaphthyl, helicene, p-cycloaranes, and their derivatives. Chiral reagents can have polymerizable groups. When both the chiral reagent and the liquid crystal compound have polymerizable groups, a polymer having repeating units derived from the polymerizable liquid crystal compound and repeating units derived from the chiral reagent can be formed by the polymerization reaction of the polymerizable chiral reagent and the polymerizable liquid crystal compound. In this manner, the polymerizable groups possessed by the polymerizable chiral reagent are preferably of the same kind as those possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable groups of the chiral reagent are preferably unsaturated polymerizable groups, epoxy groups, or acridine groups, more preferably unsaturated polymerizable groups, and even more preferably olefinically unsaturated polymerizable groups.

[0135] Furthermore, the chiral reagent can be a liquid crystal compound.

[0136] When the chiral reagent has a photoisomerizing group, it is preferable that a pattern corresponding to the desired reflection wavelength is formed by irradiation with a photomask such as activated light after coating and orientation. As the photoisomerizing group, it is preferable to be an isomerization site of a compound exhibiting photochromic properties, an azo group, an oxyazo group, or a cinnamyl group.

[0137] As specific compounds, the compounds described in Japanese Patent Application Publication Nos. 2002-080478, 2002-080851, 2002-179668, 2002-179669, 2002-179670, 2002-179681, 2002-179682, 2002-338575, 2002-338668, 2003-313189, and 2003-313292 may be used.

[0138] The content of the chiral reagent in the liquid crystal composition relative to the molar content of the liquid crystal compound is preferably 0.01 to 200 mol%, more preferably 1 to 30 mol%.

[0139] --Polymerization Initiator-- When the liquid crystal composition contains a polymerizable compound, it preferably contains a polymerization initiator. In the case of polymerization reaction carried out by ultraviolet irradiation, the polymerization initiator used is preferably a photopolymerization initiator that can initiate polymerization reaction by ultraviolet irradiation.

[0140] Examples of photopolymerization initiators include α-carbonyl compounds (described in the specifications of U.S. Patent Nos. 2,367,661 and 2,367,670), azobin ethers (described in the specification of U.S. Patent No. 2,448,828), α-hydrocarbon-substituted aromatic azobin compounds (described in the specification of U.S. Patent No. 2,722,512), polynucleoquinone compounds (described in the specifications of U.S. Patent Nos. 3,046,127 and 2,951,758), combinations of triarylimidazolium dimers and p-aminophenyl ketones (described in the specification of U.S. Patent No. 3,549,367), acridine and phenazine compounds (described in Japanese Patent Application Publication No. 60-105,667 and U.S. Patent No. 4,239,850), and oxadiazole compounds (described in the specification of U.S. Patent No. 4,212,970), etc.

[0141] The content of photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass relative to the content of the liquid crystal compound, and more preferably 0.5 to 12% by mass.

[0142] --Cross-linking agent-- The liquid crystal composition may contain any crosslinking agent to improve the strength and durability of the cured film. As a crosslinking agent, a crosslinking agent that is cured by ultraviolet light, heat, or moisture is preferred.

[0143] There are no particular limitations on the crosslinking agent; it can be appropriately selected according to the purpose. Examples include polyfunctional acrylate compounds such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; epoxy compounds such as glycidyl methacrylate and ethylene glycol diglycidyl ether; acridine compounds such as 2,2-dihydroxymethylbutanol-tris[3-(1-acrylidinyl)propionate] and 4,4-bis(ethyleneiminocarbonylamino)diphenylmethane; isocyanate compounds such as hexamethylene diisocyanate and biuret-type isocyanate; polyoxazoline compounds with oxazoline groups on the side chains; and alkoxysilane compounds such as vinyltrimethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane. Furthermore, known catalysts can be used depending on the reactivity of the crosslinking agent, thereby improving not only the film strength and durability but also the productivity. They can be used individually or in combination with two or more.

[0144] The content of the crosslinking agent relative to the mass of the solid components of the liquid crystal composition is preferably 3 to 20% by mass, more preferably 5 to 15% by mass. If the content of the crosslinking agent is within the above range, it is easy to obtain the effect of increased crosslinking density, and the stability of the cholesterol-type liquid crystal phase is further improved.

[0145] --Other Additives-- In the liquid crystal composition, polymerization inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, colorants, and metal oxide particles can be added as needed without reducing optical performance.

[0146] When forming a cholesterol-type liquid crystal layer, the liquid crystal composition is preferably used as a liquid.

[0147] The liquid crystal composition may contain a solvent. There are no limitations on the solvent; it can be appropriately selected depending on the purpose, but organic solvents are preferred.

[0148] There are no restrictions on the organic solvents used; they can be appropriately selected according to the purpose. Examples include ketones, haloalkanes, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. One or more of these can be used alone or in combination. Among these, ketones are preferred, considering their environmental impact.

[0149] When forming a cholesterol-type liquid crystal layer, it is preferable to coat a liquid crystal composition onto the formation surface of the cholesterol-type liquid crystal layer, oriented the liquid crystal compound to a state of cholesterol-type liquid crystal phase, and then cure the liquid crystal compound to form a cholesterol-type liquid crystal layer.

[0150] That is, when a cholesterol-type liquid crystal layer is formed on an alignment film, it is preferable to coat the liquid crystal composition onto the alignment film and align the liquid crystal compound to a cholesterol-type liquid crystal phase, and then cure the liquid crystal compound to form a cholesterol-type liquid crystal layer that fixes the cholesterol-type liquid crystal phase.

[0151] Furthermore, when multiple cholesterol-type liquid crystal layers are stacked, a liquid crystal composition can be coated on the already formed cholesterol-type liquid crystal layer, and after the liquid crystal compound is oriented to a state of cholesterol-type liquid crystal phase, the liquid crystal compound is cured to form a second cholesterol-type liquid crystal layer.

[0152] The coating of liquid crystal compositions can be achieved using printing methods such as inkjet and roll printing, as well as all known methods that can uniformly coat liquid onto sheets, such as spin coating, bar coating, and spray coating.

[0153] The coated liquid crystal composition is dried and / or heated as needed, and then cured to form a cholesterol-type liquid crystal layer. In this drying and / or heating process, it is sufficient that the liquid crystal compounds in the liquid crystal composition are oriented as a cholesterol-type liquid crystal phase. When heating is performed, the heating temperature is preferably below 200°C, more preferably below 130°C.

[0154] The oriented liquid crystal compound is then polymerized as needed. Polymerization can be either thermal polymerization or photopolymerization based on light irradiation, but photopolymerization is preferred. Ultraviolet light is preferably used for light irradiation. The irradiation energy is preferably 20 mJ / cm². 2 ~50J / cm 2 More preferably 50–1500 mJ / cm 2 To promote the photopolymerization reaction, light irradiation can also be carried out under heating conditions or in a nitrogen atmosphere. The wavelength of the irradiated ultraviolet light is preferably 250–430 nm.

[0155] There is no limit to the thickness of the cholesterol-type liquid crystal layer. The thickness can be appropriately set to obtain the desired light reflectance based on the light reflectance required in the cholesterol-type liquid crystal layer and the forming material of the cholesterol-type liquid crystal layer.

[0156] <Other Layers> (Absorption type linear polarizer) like Figure 3 As illustrated, the virtual image display device of the present invention may have a λ / 4 wave plate 401 and an absorptive linear polarizer 402 sequentially on the visual recognition side of the reflective circular polarizer.

[0157] Combining the λ / 4 waveplate 401 and the absorptive linear polarizer 402 allows it to function as an absorptive circular polarizer 400. For example, in the case where the reflective circular polarizer reflects right-handed circularly polarized light, by using the λ / 4 waveplate to convert the right-handed circularly polarized light that was not completely reflected by the reflective circular polarizer into linearly polarized light, and further absorbing it with the absorptive linear polarizer, ghosting can be reduced, which is therefore preferable.

[0158] The materials constituting the λ / 4 waveplate are not particularly limited, and liquid crystal compounds and polymers are examples. Regarding liquid crystal compounds, refractive index anisotropy is achieved by orienting the liquid crystal material, thereby forming a retardation layer. Polymers, by stretching or otherwise inducing refractive index anisotropy in polymer films obtained through casting or coating, can form λ / 4 waveplates. The λ / 4 waveplate is preferably a layer formed using a liquid crystal compound, and more preferably a layer formed using a liquid crystal compound having polymerizable groups.

[0159] Liquid crystal compounds used for λ / 4 waveplates are preferably liquid crystal compounds having polymerizable groups.

[0160] The liquid crystal compound can be either a liquid crystal compound exhibiting positive wavelength dispersion or negative wavelength dispersion. In the case of utilizing a retardation layer that displays the characteristics of a broadband λ / 4 waveplate in the form of a single film, a liquid crystal compound exhibiting negative wavelength dispersion is preferred, and a liquid crystal compound having two or more polymerizable groups and exhibiting negative wavelength dispersion is more preferred.

[0161] In this specification, "liquid crystal compound exhibiting reverse wavelength dispersion" refers to a liquid crystal compound that satisfies the following equations (A) and (B) when measuring the in-plane retardation (Re) value of an optical anisotropic layer made using this compound at a specific wavelength (visible light range).

[0162] Formula (A) Re(450) / Re(550)<1.00 Formula (B) Re(650) / Re(550)>1.00 As described above, the λ / 4 waveplate is preferably a layer formed using a liquid crystal compound having polymerizable groups, and more preferably a layer formed by fixing the orientation state of a liquid crystal compound having polymerizable groups.

[0163] There are no particular limitations on the desirable orientation states of liquid crystal compounds containing polymerizable groups. Examples include uniform orientation, vertical orientation, twisted orientation, cholesterol-type orientation, mixed orientation, and tilted orientation. Specifically, a mixed orientation refers to an orientation in which the tilt angle of the liquid crystal compound changes continuously from one surface to another. Tilted orientation specifically refers to an orientation in which the tilt angle of the liquid crystal compound is constant from one surface to another. Furthermore, a twisted orientation indicates an orientation in which the liquid crystal compound is twisted about its thickness direction as an axis of rotation. When the liquid crystal compound is twisted and has a specified tilt angle (tilted angle greater than 0°), it is equivalent to a twisted mixed orientation. In this specification, a twisted orientation corresponds to a liquid crystal compound with a twist angle less than 360°, and the aforementioned cholesterol-type orientation corresponds to a liquid crystal compound with a twist angle of 360° or more.

[0164] A λ / 4 waveplate formed using liquid crystal compounds can have multiple regions along the thickness direction where the liquid crystal compounds have different orientation states. For example, a λ / 4 waveplate can have regions along the thickness direction where the liquid crystal compounds are uniformly oriented and regions where the liquid crystal compounds are twistedly oriented.

[0165] There is no particular limitation on the thickness of the λ / 4 waveplate, but it is preferably 0.1 to 10.0 μm, more preferably 0.5 to 5.0 μm.

[0166] As specific examples of the structure of a broadband λ / 4 waveplate, waveplates composed of a single-layer phase retardation layer can be cited, such as the phase retardation layer using liquid crystal compounds exhibiting reverse wavelength dispersion disclosed in International Publication No. 2019 / 160016, Japanese Patent Application Publication No. 2020-173460 and International Publication No. 2021 / 157694, and the λ / 4 waveplate having multiple regions with different orientation states of liquid crystal compounds along the thickness direction disclosed in International Publication No. 2022 / 030308 and Japanese Patent Application Publication No. 2022-184691. Furthermore, as a waveplate composed of two or more phase difference layers, examples can be given of the combined λ / 4 and λ / 2 phase difference layers disclosed in Japanese Patent Application Publication No. 2001-108825, Japanese Patent Application Publication No. 2001-91741 and International Publication No. 2013 / 137464, as well as the combined twisted-oriented phase difference layers and other phase difference layers disclosed in Japanese Patent Application Publication No. 2001-21720, Japanese Patent Application Publication No. 2014-209219 and International Publication No. 2022 / 255105.

[0167] Furthermore, in order to compensate for the phase difference change of the incident light relative to the tilt direction, other phase difference layers such as positive C-plate and negative C-plate can be added to the λ / 4 waveplate.

[0168] (Absorption type linear polarizer) An absorption-type linear polarizer is a linear polarizer that absorbs linearly polarized light along the absorption axis of incident light and transmits linearly polarized light along the transmission axis.

[0169] As an absorption-type linear polarizer, it can be compatible with known absorption-type linear polarizers, such as polarizers that orient dichroic substances by dyeing them on polyvinyl alcohol and other polymer resins and stretching them, or polarizers that orient dichroic substances by utilizing the orientation of liquid crystal compounds.

[0170] Regarding the thickness of the absorptive linear polarizer, it is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. If the absorptive linear polarizer is thin, cracks and breaks can be prevented when stretching or molding it.

[0171] Furthermore, the transmittance of the single-plate of the absorption-type linear polarizer is preferably 40% or more, more preferably 42% or more. The degree of polarization is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more. In this specification, the transmittance and degree of polarization of the single-plate of the absorption-type linear polarizer are measured using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation).

[0172] The angle between the transmission axis of the absorptive linear polarizer and the slow axis of the λ / 4 waveplate is preferably 45±10°, more preferably 45±5°, and even more preferably 45±3°.

[0173] As described above, the absorption-type linear polarizer is preferably a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic material. Linear polarizers containing liquid crystal compounds and dichroic materials can be made thinner, and are less prone to cracking and breakage even during stretching and molding, therefore they are preferred.

[0174] The thickness of the light-absorbing anisotropic layer is not particularly limited, but from the viewpoint of thinning, it is preferably 0.1 to 8 μm, and more preferably 0.3 to 5 μm.

[0175] Regarding linear polarizers containing liquid crystal compounds and dichroic materials, reference can be made, for example, to Japanese Patent Application Publication No. 2020-023153. From the viewpoint of improving the polarization degree of the linear polarizer, the orientation degree of the dichroic material in the light-absorbing anisotropic layer is preferably 0.95 or higher, more preferably 0.97 or higher.

[0176] The liquid crystal compound contained in the composition for forming the light-absorbing anisotropic layer is preferably a liquid crystal compound that does not exhibit dichroism in the visible region.

[0177] As the liquid crystal compound, either a low-molecular-weight liquid crystal compound or a high-molecular-weight liquid crystal compound can be used. Here, "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound that does not have repeating units in its chemical structure. And, "high-molecular-weight liquid crystal compound" refers to a liquid crystal compound that has repeating units in its chemical structure.

[0178] Examples of polymeric liquid crystal compounds include, for instance, the thermotropic liquid crystal polymer described in Japanese Patent Application Publication No. 2011-237513. Furthermore, the polymeric liquid crystal compound preferably has crosslinking groups (e.g., acryloyl and methacryloyl groups) at its ends.

[0179] A single liquid crystal compound can be used alone, or two or more can be used in combination. It is also preferred to use a combination of high molecular weight liquid crystal compounds and low molecular weight liquid crystal compounds.

[0180] The content of the liquid crystal compound is preferably 25 to 2000 parts by mass relative to the content of the dichroic substance in the composition (100 parts by mass), more preferably 33 to 1000 parts by mass, and even more preferably 50 to 500 parts by mass. With the liquid crystal compound content within the above range, the orientation degree of the polarizer is further improved.

[0181] There are no particular limitations on the dichroic substance contained in the composition for forming the light-absorbing anisotropic layer. Examples include visible light absorbing substances (dichroic pigments), ultraviolet light absorbing substances, infrared light absorbing substances, nonlinear optical substances, carbon nanotubes, etc. Existing known dichroic substances (dichroic pigments) can be used.

[0182] In an absorption-type linear polarizer, two or more dichroic materials may be used together. For example, from the viewpoint of obtaining a high degree of polarization over a wider wavelength range, it is preferable to use at least one dichroic material with a maximum absorption wavelength in the wavelength range of 370 to 550 nm and at least one dichroic material with a maximum absorption wavelength in the wavelength range of 500 to 700 nm.

[0183] The reflective circular polarizer, λ / 4 waveplate, and absorptive linear polarizer used in the virtual image display device of the present invention may include a support and / or an orientation layer, etc.

[0184] Alternatively, the reflective circular polarizer, λ / 4 waveplate, and absorptive linear polarizer used in the virtual image display device of the present invention have a support and / or alignment layer during manufacturing, and the support or alignment layer can eventually be peeled off. That is, the support and alignment layer can be a pre-support that is eventually peeled off and removed.

[0185] By peeling off and removing the pre-support, the virtual image display device can be made thinner, and the adverse effects of the phase difference of the pre-support on the polarization of the transmitted light can be eliminated, which is therefore preferred.

[0186] There are no particular restrictions on the type of support, but it is preferable to be transparent to visible light. Examples of supports include films (sheets) composed of triacetyl cellulose, polyethylene terephthalate film, polyethylene, polypropylene, norbornene polymers and other polyolefins; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; acrylic resins such as polymethacrylate and polyacrylate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; polyphenylene sulfide and polyphenylene ether.

[0187] Furthermore, commercially available products can also be used for the support structure. Examples of commercially available products include TECHNOLLOY S001G, TECHNOLLOY S014G, TECHNOLLOY S000, TECHNOLLOY C001 and TECHNOLLOY C000 (SumikaAcryl Co., Ltd), Lumirror U type and Lumirror FX10, Lumirror SF20 (TORAY INDUSTRIES, INC.), HK-53A (Higashiyama Film Co. Ltd), Teflex FT3 (Teijin Film Solutions Limited), Esushina and SCA40 (SEKISUI CHEMICAL CO., LTD.), ZEONOR Film (Optes Inc.), and ARTON Film (JSR Corporation).

[0188] Furthermore, in order to minimize the impact on various sensors that use near-infrared light as a light source, such as eye tracking, expression recognition, and iris authentication, which are assembled in optical systems such as virtual reality display devices and electronic viewfinders, the reflective circular polarizer, λ / 4 waveplate, and absorptive linear polarizer used in the virtual image display device of the present invention are preferably transmissive to near-infrared light.

[0189] (Other functional layers) In addition to the reflective circular polarizer, λ / 4 waveplate and absorptive linear polarizer, the virtual image display device of the present invention may also have other functional layers.

[0190] As such functional layers, examples such as a positive C-plate and an anti-reflective layer are preferred, and the virtual image display device of the present invention preferably includes these.

[0191] (Reflective optical system) In the virtual image display device of the present invention, the reflective circular polarizer, λ / 4 waveplate, and absorptive linear polarizer used are preferably attached to the surface of the lens to form a reflective optical system. In this case, it is preferable to form a semi-reflective mirror on the surface of the lens opposite to the surface on which the reflective circular polarizer is attached.

[0192] Furthermore, the reflective circular polarizer, the λ / 4 waveplate, and the absorptive linear polarizer can also be shaped into curved surfaces according to the surface shape of the lens. From the viewpoint of minimizing image distortion and aberrations, these components are preferably shaped into curved surfaces according to the surface shape of the lens.

[0193] There are no restrictions on the methods for shaping reflective circular polarizers, λ / 4 wave plates, and absorptive linear polarizers into curved surfaces; various known methods corresponding to the forming materials and layer structures of reflective circular polarizers, etc., can be used.

[0194] There are no limitations on the type of lens used; various known lenses can be used. Examples of lenses include convex lenses and concave lenses. Examples of convex lenses include biconvex lenses, plano-convex lenses, and convex meniscus lenses. Examples of concave lenses include biconcave lenses, plano-concave lenses, and concave meniscus lenses.

[0195] As a lens material, materials that are transparent to visible light, such as glass, crystals, and plastics, can be used.

[0196] Birefringence of a lens can cause rainbow-like inhomogeneity and light leakage, so a material with small, and more preferably, virtually zero, birefringence is preferred.

[0197] <Image display device> In the virtual image display device of the present invention, the image display device (image display element (display panel)) is not limited, and various known image display devices used in virtual image display devices and the like can be utilized.

[0198] Examples of image display devices include liquid crystal displays (LCDs), organic light-emitting diode (OLEDs), cathode ray tubes (CRTs), electronic paper, LEDs (LEDs), micro LEDs, digital light processing (DLPs), and MEMS (Micro-Electro-Mechanical Systems) displays.

[0199] Furthermore, in the virtual image display device of the present invention, the image display device may have optical elements such as a phase difference layer (λ / 4 waveplate) and a linear polarizer as described above, as needed. Additionally, when the image display element is a liquid crystal display or other element that emits linearly polarized light, a linear polarizer is not required.

[0200] Example The present invention will now be described in more detail with reference to the embodiments.

[0201] The materials, quantities, proportions, processing contents, and processing steps shown in the following embodiments can be appropriately modified as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as limited by the embodiments shown below.

[0202] [Preparation of coating solution for reflective layer] [Reflective layer coating liquid R-1] The following composition was stirred and dissolved in a container maintained at 70°C to prepare a coating solution R-1 for the reflective layer. Here, R indicates a coating solution using a rod-shaped liquid crystal compound.

[0203] ―――――――――――――――――――――――――――――――― Reflective layer coating liquid R-1 ―――――――――――――――――――――――――――――――― · 120.9 parts by weight of methyl ethyl ketone · Cyclohexanone 21.3 parts by weight • A mixture of the following rod-shaped liquid crystal compounds x 100.0 parts by mass • 1.00 parts by weight of the following photopolymerization initiator B • 4.18 parts by weight of the following chiral reagent A • 0.1 parts by weight of the following surfactant F1 ―――――――――――――――――――――――――――――――― Mixture of rod-shaped liquid crystal compounds X [Chemical Formula 1] In the above mixture X, the values ​​are by mass%. Furthermore, R is a group bonded to an oxygen atom. Moreover, the above rod-shaped liquid crystal compound has an average molar absorptivity of 140 / mol·cm at wavelengths of 300–400 nm.

[0204] Chiral reagent A [Chemical Formula 2] Surfactant F1 [Chemical Formula 3] Photopolymerization initiator B [Chemical Formula 4] In addition, chiral reagent A is a chiral reagent whose helical torsional power (HTP) is reduced by light.

[0205] [Reflective layer coating liquid R-2] The amount of chiral reagent A added is changed as shown in Table 1 below, otherwise it is prepared in the same manner as the coating solution R-1 for the reflective layer.

[0206] [Table 1]

[0207] [Reflective layer coating liquid D-1] The composition shown below was stirred and dissolved in a container maintained at 50°C to prepare a coating solution D-1 for a reflective layer. Here, D indicates a coating solution using a disc-shaped liquid crystal compound.

[0208] ―――――――――――――――――――――――――――――――― Reflective layer coating liquid D-1 ―――――――――――――――――――――――――――――――― • 80 parts by weight of the following disc-shaped liquid crystal compound (A) • 20 parts by weight of the following disc-shaped liquid crystal compound (B) • 10 parts by weight of the following polymerizable monomer E1 • 0.3 parts by weight of the following surfactant F2 • Photopolymerization initiator (manufactured by BASF, IRGACURE-907) 3 parts by weight • 5.45 parts by weight of the above chiral reagent A 290 parts by weight of methyl ethyl ketone 50 parts by weight of cyclohexanone ―――――――――――――――――――――――――――――――― Disc-shaped liquid crystal compound (A) [Chemical Formula 5] Disc-shaped liquid crystal compound (B) [Chemical Formula 6] Polymerizable monomer E1 [Chemical Formula 7] Surfactant F2 [Chemical Formula 8] [Reflective layer coating solutions D-2 and D-3] The amount of chiral reagent A added was changed as shown in Table 2 below. Otherwise, it was prepared in the same manner as the coating solution D-1 for the reflective layer.

[0209] [Table 2]

[0210] [Fabrication of Reflective Circular Polarizer 1] As a pre-support, a 100 μm thick PET film (manufactured by TOYOBO CO., LTD., A4265) was prepared, and the PET surface on the side without the easy-to-adhesive layer was rubbed.

[0211] After applying the prepared reflective coating solution R-1 using a wire bar coater, it was dried at 110°C for 72 seconds. Subsequently, it was irradiated at 100°C with an illuminance of 80 mW / cm² under a low-oxygen atmosphere (below 100 ppm). 2 Irradiation dose 500mJ / cm 2 The light from a metal halide lamp is used for curing, thereby forming a first blue light-reflecting layer (first cholesteric liquid crystal layer) composed of a cholesteric liquid crystal layer. Light irradiation is performed from the cholesteric liquid crystal layer side. At this time, the coating thickness is adjusted so that the cured first blue light-reflecting layer has a film thickness of 2.6 μm.

[0212] Next, with a discharge rate of 150 W·min / m 2 After corona treatment of the first blue light reflective layer, a reflective coating liquid D-1 was applied to the corona-treated surface using a wire bar coater.

[0213] Next, the coated film was dried at 70°C for 2 minutes to vaporize the solvent, and then heated at 115°C for 3 minutes to achieve a uniform orientation. Afterward, the coated film was held at 45°C and irradiated with ultraviolet light (300 mJ / cm²) under a nitrogen atmosphere using a metal halide lamp. 2The coating is cured to form a second blue light reflective layer (second cholesteric liquid crystal layer) on the first blue light reflective layer. Light irradiation is performed from the cholesteric liquid crystal layer side. At this time, the coating thickness is adjusted so that the thickness of the cured second blue light reflective layer is 2.0 μm.

[0214] Next, a reflective coating liquid D-2 was applied to the second blue light reflective layer using a wire bar coater. The coated film was then dried at 70°C for 2 minutes to vaporize the solvent, followed by curing at 115°C for 3 minutes to achieve a uniform orientation.

[0215] The coated film was then kept at 45°C and irradiated with ultraviolet light (300 mJ / cm²) under a nitrogen atmosphere using a metal halide lamp. 2 The coating is cured to form a green light-reflecting layer (the third cholesterol-type liquid crystal layer) on the second blue light-reflecting layer. Light irradiation is performed from the cholesterol-type liquid crystal layer side. At this time, the coating thickness is adjusted so that the thickness of the cured green light-reflecting layer is 2.7 μm.

[0216] Next, the reflective coating liquid R-2 was applied to the green light reflective layer using a bar coater, and then dried at 110°C for 72 seconds.

[0217] Subsequently, under a low-oxygen atmosphere (below 100 ppm), the sample was irradiated at 100°C with an illuminance of 80 mW and an irradiation dose of 500 mJ / cm². 2 The coating is cured using light from a metal halide lamp, thereby forming a red light-reflecting layer (the fourth cholesterol-type liquid crystal layer) on the green light-reflecting layer. The light irradiation is performed from the cholesterol-type liquid crystal layer side. The coating thickness is then adjusted so that the cured red light-reflecting layer has a thickness of 3.4 μm.

[0218] Next, with a discharge rate of 150 W·min / m 2 After corona treatment of the red light reflective layer, a reflective coating liquid D-3 was applied to the corona-treated surface using a wire bar coater. Next, the coating film was dried at 70°C for 2 minutes to vaporize the solvent, and then heated at 115°C for 3 minutes to achieve a uniform orientation.

[0219] The coated film was then kept at 45°C and irradiated with ultraviolet light (300 mJ / cm²) under a nitrogen atmosphere using a metal halide lamp. 2 The process involves curing the coating to form a yellow light-reflecting layer (the fifth cholesterol-type liquid crystal layer) on top of the red light-reflecting layer. Light irradiation is performed from the cholesterol-type liquid crystal layer side. The coating thickness is then adjusted so that the cured yellow light-reflecting layer has a thickness of 3.4 μm.

[0220] The above steps yielded a reflective circular polarizer 1 having sequentially arranged cholesterol-type liquid crystal layers 1 to 5.

[0221] Table 3 shows the reflection center wavelength and film thickness of each cholesteric liquid crystal layer in the fabricated reflective circular polarizer 1. Here, the reflection center wavelength shown in Table 3 corresponds to the center wavelength of the reflected light from the aforementioned cholesteric liquid crystal layers. The reflection center wavelength (center wavelength of the reflected light) was confirmed by fabricating a single-layer film coated only with each cholesteric liquid crystal layer. The film thickness was confirmed using SEM.

[0222] [Table 3]

[0223] Furthermore, by peeling off the pre-support (PET film) of the obtained reflective circular polarizer 1, SHG measurements were performed on the surface of the first cholesterol-type liquid crystal layer (layer 1). The results showed that the orientation degree of the liquid crystal compound was 0.65. Moreover, within the effective area when assembled into a virtual image display device, the orientation deviation of the liquid crystal compound's director was 3.2°.

[0224] Furthermore, SHG measurements were performed on the surface of the fifth cholesterol-type liquid crystal layer (fifth layer) side of the reflective circular polarizer 1, and the orientation degree of the liquid crystal compound was found to be 0.62. Moreover, within the effective area when assembled into a virtual image display device, the orientation deviation of the liquid crystal compound's director was 85°.

[0225] [Construction of Reflective Circular Polarizer 2] [Reflective layer coating liquid R-3] The composition shown below was stirred and dissolved in a container maintained at 70°C to prepare a coating solution R-3 for a reflective layer. Here, R indicates a coating solution using a rod-shaped liquid crystal compound.

[0226] ―――――――――――――――――――――――――――――――― Reflective layer coating liquid R-3 ―――――――――――――――――――――――――――――――― · 120.9 parts by weight of methyl ethyl ketone · Cyclohexanone 21.3 parts by weight • 100.0 parts by weight of the following rod-shaped liquid crystal compound X2 • 1.00 parts by weight of the above photopolymerization initiator B • 4.18 parts by weight of the above chiral reagent A • 0.1 parts by weight of the above surfactant F1 ―――――――――――――――――――――――――――――――― Rod-shaped liquid crystal compound X2 [Chemical Formula 9] [Reflective layer coating liquid R-4] The amount of chiral reagent A added was changed as shown in Table 4 below, and otherwise it was prepared in the same manner as the coating solution R-3 for the reflective layer.

[0227] [Table 4]

[0228] [Reflective layer coating liquid D-4] The composition shown below was stirred and dissolved to prepare a coating solution D-4 for a reflective layer. Here, D indicates a coating solution using a disc-shaped liquid crystal compound.

[0229] ―――――――――――――――――――――――――――――――― D-4 coating liquid for reflective layer ―――――――――――――――――――――――――――――――― 100 parts by weight of the following disc-shaped liquid crystal compound (C) • 10 parts by mass of the above polymerizable monomer E1 • 0.3 parts by weight of the above surfactant F2 • Photopolymerization initiator (manufactured by BASF, IRGACURE-907) 3 parts by weight • 5.45 parts by weight of the above chiral reagent A • Dichloromethane: 340 parts by weight ―――――――――――――――――――――――――――――――― Disc-shaped liquid crystal compound (C) [Chemical Formula 10] [Reflective layer coating solutions D-5 and D-6] The amount of chiral reagent A added was changed as shown in Table 5 below. Otherwise, it was prepared in the same manner as the coating solution D-4 for the reflective layer.

[0230] [Table 5]

[0231] Using these coating solutions, the cured film thickness was adjusted to the values ​​recorded in Table 6, and otherwise coated in the same manner as the reflective circular polarizer 1, thus producing the reflective circular polarizer 2.

[0232] Therefore, in the reflective circular polarizer 2, similarly to the reflective circular polarizer 1, the first layer (the first cholesterol-type liquid crystal layer) is formed on the alignment film.

[0233] [Table 6]

[0234] The pre-support (PET film) of the obtained reflective circular polarizer 2 was peeled off, and the surface of the first cholesterol-type liquid crystal layer (layer 1) was measured by SHG. The results showed that the orientation degree of the liquid crystal compound was 0.67. Furthermore, within the effective area when assembled into a virtual image display device, the orientation deviation of the liquid crystal compound's director was 2.6°.

[0235] Furthermore, SHG measurements were performed on the surface of the fifth cholesterol-type liquid crystal layer (fifth layer) side of the reflective circular polarizer 2, and the orientation degree of the liquid crystal compound was found to be 0.64. Moreover, within the effective area when assembled into a virtual image display device, the orientation deviation of the liquid crystal compound's director was 79°.

[0236] [Preparation of a λ / 4 wave plate] A λ / 4 waveplate with inverse wavelength dispersion was fabricated using the method described in paragraphs 0151 to 0163 of Japanese Patent Application Publication No. 2020-084070.

[0237] In λ / 4 waveplate 1, Re = 141 nm and Rth = 71 nm.

[0238] [Making C-plate 2] The film thickness was adjusted according to the method described in paragraphs 0132 to 0134 of Japanese Patent Application Publication No. 2016-053709, thereby producing the positive C plate 2. However, the support was changed from polyethylene terephthalate film (PET film) to triacetyl cellulose film (TAC film).

[0239] In positive C plate 2, Re = 0.1 nm, Rth = -80 nm.

[0240] [Making of a Straight Linear Deviation Machine] A linear deflector was fabricated using the following steps.

[0241] (Preparation of cellulose acylate membrane 1) <Preparation of Core Layer Cellulose Acid Pulp> The following composition was added to a mixing tank, stirred and dissolved to prepare a cellulose acetate solution for use as a core layer cellulose acylated paste.

[0242] ―――――――――――――――――――――――――――――――― Core layer cellulose acylated gel ―――――――――――――――――――――――――――――――― 100 parts by weight of cellulose acetate with a degree of acetyl substitution of 2.88 The embodiments described in Japanese Patent Application Publication No. 2015-227955 Polyester compound B 12 parts by weight • 2 parts by mass of the following compound F • Dichloromethane (primary solvent) 430 parts by weight • Methanol (second solvent) 64 parts by weight ―――――――――――――――――――――――――――――――― Compound F [Chemical Formula 11] <Preparation of outer cellulose acylated gel> A cellulose acetate solution for use as an outer cellulose acylated paste was prepared by adding 10 parts by mass of the following matting agent solution to 90 parts by mass of the core layer cellulose acylated paste.

[0243] ―――――――――――――――――――――――――――――――― Matting solution ―――――――――――――――――――――――――――――――― • Silica particles with an average particle size of 20 nm (AEROSIL R972, NIPPON AEROSIL CO.,LTD.) 2 parts by weight • Dichloromethane (primary solvent) 76 parts by mass • Methanol (second solvent) 11 parts by weight · 1 part by weight of the above-mentioned core layer cellulose acylated gel ―――――――――――――――――――――――――――――――― <Preparation of Cellulose Acylate Membrane 1> After filtering the core cellulose acylated slurry and the outer cellulose acylated slurry with filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm, the core cellulose acylated slurry and the outer cellulose acylated slurries on both sides are simultaneously cast from the casting port onto a roller at 20°C (belt casting machine).

[0244] Next, the film was peeled off with a solvent content of approximately 20% by mass, and the two ends of the film in the width direction were fixed by the tenter frame clamps. It was then dried while being stretched laterally at a stretch ratio of 1.1.

[0245] Subsequently, the film was further dried by conveying it between rollers in a heat treatment apparatus, thereby producing an optical film with a thickness of 40 μm, which was designated as cellulose acylated film 1. The Re of the obtained cellulose acylated film 1 was 0 nm.

[0246] (Formation of the photo-alignment layer PA1) The oriented layer forming coating solution S-PA-1 (described later) was continuously coated onto the cellulose acylated membrane 1 using a wire rod. The support with the coated film was dried with warm air at 140°C for 120 seconds, and then the coating was irradiated with polarized ultraviolet light (10 mJ / cm²). 2 Using an ultra-high pressure mercury lamp, a photo-alignment layer PA1 was formed. The film thickness was 0.3 μm.

[0247] ―――――――――――――――――――――――――――――――― (Coating solution S-PA-1 for orientation layer formation) ―――――――――――――――――――――――――――――――― • 100.00 parts by weight of the following polymer M-PA-1 • 5.00 parts by weight of the following acid-producing agent PAG-1 • 0.005 parts by weight of the following acid-producing agent CPI-110TF · Xylene 1220.00 parts by weight · 122.00 parts by weight of methyl isobutyl ketone ―――――――――――――――――――――――――――――――― Polymer M-PA-1 [Chemical Formula 12] Acid-producing agent PAG-1 [Chemical Formula 13] Acid-producing agent CPI-110TF [Chemical Formula 14] (Formation of the light-absorbing anisotropic layer P1) The following light-absorbing anisotropic layer forming coating liquid SP-1 was continuously applied onto the obtained photo-alignment layer PA1 using a wire rod to form a coating layer.

[0248] Next, the formed coating layer was heated at 140°C for 30 seconds and then cooled to room temperature (23°C). Then, it was heated at 90°C for 60 seconds and then cooled to room temperature again.

[0249] Then, LED lights (center wavelength 365nm) were used at an illuminance of 200mW / cm². 2 Irradiation was performed for 2 seconds under the specified irradiation conditions, thereby forming an anisotropic light absorption layer P1 on the light alignment layer PA1. The film thickness was 1.6 μm.

[0250] ―――――――――――――――――――――――――――――――― Composition of coating solution SP-1 for forming anisotropic light-absorbing layers ―――――――――――――――――――――――――――――――― • 0.25 parts by mass of the following dichroic substance D-1 • 0.36 parts by mass of the following dichroic substance D-2 • 0.59 parts by mass of the following dichroic substance D-3 • 2.21 parts by weight of the following polymeric liquid crystal compound MP-1 • 1.36 parts by mass of the following low molecular weight liquid crystal compound M-1 Polymerization initiators IRGACURE OXE-02 (manufactured by BASF) 0.200 parts by weight • 0.026 parts by weight of the following surfactant F-3 46.00 parts by weight of cyclopentanone 46.00 parts by weight of tetrahydrofuran · 3.00 parts by weight of benzyl alcohol ―――――――――――――――――――――――――――――――― Dichroic substance D-1 [Chemical Formula 15] Dichroic substance D-2 [Chemical Formula 16] Dichroic substance D-3 [Chemical Formula 17] MP-1, a polymeric liquid crystal compound [Chemical Formula 18] Low molecular weight liquid crystal compound M-1 [Chemical Formula 19] Surfactant F-3 [Chemical Formula 20] [Fabrication of laminated films] By bonding the above components together through the following steps, laminated film 1 and laminated film 2 are obtained.

[0251] UV adhesive Chemiseal U2084B (manufactured by KEMITEC CO.,LTD., refractive index n1.60 after curing) was applied to a PMMA substrate using a wire bar coater until a thickness of 2 μm was achieved. An anisotropic light-absorbing layer P1 was then bonded onto the formed adhesive layer. Additionally, the surface of the anisotropic light-absorbing layer P1, opposite to the pre-support (cellulose acylate film 1), was laminated to contact the adhesive layer using a laminator.

[0252] Next, the adhesive layer was purged with nitrogen in a nitrogen purging chamber until the oxygen concentration was below 100 ppm. Then, ultraviolet light from a high-pressure mercury lamp was irradiated from the pre-support side of the anisotropic light-absorbing layer P1 to cure the adhesive layer. The illuminance was 25 mW / cm². 2 The irradiation dose was 1000 mJ / cm. 2 .

[0253] Finally, the pre-support of the light-absorbing anisotropic layer P1 was stripped off.

[0254] For the exposed surface of the light-absorbing anisotropic layer P1, a UV adhesive layer is formed using the same steps as described above, and a λ / 4 waveplate 1 is then bonded to it. The layers are stacked such that the angle between the slow axis of the λ / 4 waveplate 1 and the absorption axis of the light-absorbing anisotropic layer P1 is 45°.

[0255] Next, for the λ / 4 waveplate 1, a UV adhesive layer is formed by the same transfer steps as described above, and the positive C plate 2 is attached.

[0256] Finally, for the positive C-plate 2, the reflective circular polarizer 1 was bonded together by forming a UV adhesive layer using the same steps as described above, thereby fabricating the laminated film 1. Furthermore, the UV adhesive layer was bonded so that the surface of the fifth cholesteric liquid crystal layer side of the reflective circular polarizer 1 was in contact with it. Then, the PET film of the reflective circular polarizer 1 was peeled off from the laminated film 1, exposing the surface of the first cholesteric liquid crystal layer.

[0257] The laminated film 1 sequentially comprises a reflective circular polarizer 1, a positive C-plate 2, a λ / 4 waveplate 1, and a light-absorbing anisotropic layer 1.

[0258] The reflective circular polarizer 2 was used instead of the reflective circular polarizer 1. Otherwise, the laminated film 2 with the reflective circular polarizer 2 was fabricated by the same steps as when the laminated film 1 was obtained.

[0259] [Fabrication of a telescopic optical system] [A semi-reflective mirror is formed on the lens] Aluminum was vapor-deposited onto the convex side of the lens (a convex meniscus lens LE1076-A (2 inches in diameter, 100 mm focal length) manufactured by Thorlabs, Inc.) until the reflectivity reached 40%, thus forming a semi-reflective mirror. Lens 1 with a semi-reflective mirror was obtained through the above steps.

[0260] [Forming of the reflective circular polarizer and fabrication of the folding optical system 1] A reflective optical system 1 was fabricated by molding the manufactured reflective circular polarizer 1 onto the concave side of the lens 1 with a semi-reflective mirror and then attaching it to the surface.

[0261] The forming and bonding of the reflective circular polarizer 1 on the curved surface is carried out through the following steps.

[0262] First, an adhesive sheet “NCF-D692 (5)” manufactured by LINTEC Corporation was attached to the surface of the first cholesteric liquid crystal layer of the reflective circular polarizer 1. With the release film of the adhesive sheet removed, the adhesive sheet was positioned opposite the concave surface of the lens 1 with the semi-reflective mirror, and the first cholesteric liquid crystal layer was placed there. Vacuum forming was then performed using the method described in Japanese Patent Application Publication No. 2012-116094. The forming temperature was set to 110°C.

[0263] Thus, a circular reflector polarizer 1 is formed, and a folding optical system 1 is fabricated by attaching the circular reflector polarizer 1 to the concave surface of the lens 1 with a semi-reflective mirror.

[0264] [Fabrication of the Virtual Image Display Device in Example 1] The lens section of the virtual reality display device "PICO4" manufactured by PICO Corporation was disassembled, and the refracting optical system was removed.

[0265] The PICO4 image display device emits left-handed circularly polarized light. Therefore, the polarizer on the surface of the image display device is peeled off and replaced with a circularly polarizer that emits right-handed circularly polarized light.

[0266] Next, the fabricated reflective optical system 1 is assembled to replace the removed reflective optical system, thereby creating the virtual image display device of Embodiment 1. At this time, the reflective optical system 1 is configured such that its convex side, i.e., the semi-reflective mirror side, becomes the image display device side.

[0267] Therefore, in this example, the first cholesteric liquid crystal layer (first layer) of the reflective circular polarizer 1 becomes the surface on the side of the image display device.

[0268] [Fabrication of the Virtual Image Display Device in Example 2] The reflective circular polarizer 2 is used instead of the reflective circular polarizer 1. Otherwise, the reflective optical system is made in the same manner as the reflective optical system 1.

[0269] Using the refracting optical system, the virtual image display device of Embodiment 2 was fabricated in the same manner as in Embodiment 1.

[0270] Therefore, in this example, the first cholesteric liquid crystal layer (first layer) of the reflective circular polarizer 2 becomes the surface on the side of the image display device.

[0271] [Fabrication of the Virtual Image Display Device in Example 3] A laminated film 1 is used instead of the reflective circular polarizer 1. Otherwise, the reflective optical system is fabricated in the same manner as the reflective optical system 1.

[0272] Using the refracting optical system, the virtual image display device of Embodiment 3 was fabricated in the same manner as in Embodiment 1.

[0273] In addition, when the laminated film 1 is formed into a lens 1 with a half-reflective mirror, the first cholesterol-type liquid crystal layer side of the reflective circular polarizer 1 in the laminated film 1 is made into the concave side of the lens 1 with the half-reflective mirror, and the forming temperature is set to 110°C.

[0274] Therefore, in this example, the first cholesteric liquid crystal layer (first layer) of the reflective circular polarizer 1 of the laminated film 1 becomes the surface on the side of the image display device.

[0275] [Fabrication of the Virtual Image Display Device in Example 4] A laminated film 2 is used instead of the reflective circular polarizer 1. Otherwise, the reflective optical system is fabricated in the same manner as the reflective optical system 1.

[0276] Using this reflective optical system, the virtual image display device of Embodiment 4 was fabricated in the same manner as in Embodiment 1.

[0277] In addition, when the laminated film 2 is formed into a lens 1 with a semi-reflective mirror, the first cholesterol-type liquid crystal layer side of the reflective circular polarizer 2 in the laminated film 2 is made into the concave side of the lens 1 with a semi-reflective mirror, and the forming temperature is set to 110°C.

[0278] Therefore, in this example, the first cholesteric liquid crystal layer (first layer) of the reflective circular polarizer 2 of the laminated film 2 becomes the surface on the side of the image display device.

[0279] [The fabrication of the virtual image display device in Comparative Example 1] When the reflective circular polarizer 1 is formed into a lens 1 with a half-reflective mirror, the fifth cholesterol-type liquid crystal layer side of the reflective circular polarizer 1 is made into the concave side of the lens 1 with the half-reflective mirror. Otherwise, the reflective optical system is manufactured in the same manner as the reflective optical system 1.

[0280] Using this reflective optical system, the virtual image display device of Comparative Example 1 was fabricated in the same manner as in Example 1.

[0281] Therefore, in this example, the fifth cholesterol-type liquid crystal layer (the fifth layer) of the reflective circular polarizer 1 becomes the surface on the side of the image display device.

[0282] [evaluate] [Evaluation of the double image] Five virtual image display devices for the embodiments and comparative examples were manufactured using the same manufacturing steps.

[0283] A black and white checkerboard pattern was displayed on the image display panel of the fabricated virtual image display device, and the visual recognition of the ghosting was evaluated by the naked eye according to the following criteria.

[0284] In practical terms, ratings of A to C are preferred, with ratings of A or B being even more preferred.

[0285] A: Completely invisible.

[0286] B: Although slightly visible, it is not obvious.

[0287] C: A faint double image is visible.

[0288] D: Slightly strong ghosting is visible.

[0289] E: Strong ghosting is visible.

[0290] The evaluation results of ghosting in the examples and comparative examples are shown in Table 7.

[0291] In addition, the evaluation values ​​for the case with the minimum ghosting and the case with the maximum ghosting are shown respectively when 5 evaluations were performed.

[0292] [Table 7]

[0293] According to the results shown in Table 7, in the virtual image display devices of Examples 1 to 4, the visual recognition of ghosting is stable and small, with little deviation. On the other hand, in the virtual image display device of Comparative Example 1, the visual recognition of ghosting varies from person to person, with the ghosting being strongly visually recognized in the worst individual.

[0294] Symbol Explanation 10, 11, 12 - Rays; 200 - Reflective circular polarizer; 300 - Semi-reflective mirror; 400 - Circular polarizer; 401 - λ / 4 waveplate; 402 - Absorption-type linear polarizer; 500 - Image display device; 600 - Reflective optical system; 1000 - Virtual image display device.

Claims

1. A virtual image display device, comprising at least an image display device and a refracting optical system including a reflective circular polarizer, wherein, The reflective circular polarizer includes a cholesterol-type liquid crystal layer. On the image display device side of the cholesterol-type liquid crystal layer, the orientation degree of the liquid crystal compound is 0.5 or higher, and the deviation of the azimuth of the liquid crystal compound in the effective area is 30° or less.

2. The virtual image display device according to claim 1, wherein, The reflective circular polarizer includes multiple cholesterol-type liquid crystal layers.

3. The virtual image display device according to claim 2, wherein, The reflective circular polarizer includes at least a cholesterol-type liquid crystal layer formed using a first liquid crystal compound that is substantially composed of rod-shaped liquid crystal compounds, and a cholesterol-type liquid crystal layer formed using a second liquid crystal compound that is substantially composed of disk-shaped liquid crystal compounds.

4. The virtual image display device according to any one of claims 1 to 3, wherein, The reflective circular polarizer is formed by at least sequentially stacking a λ / 4 wave plate and an absorptive linear polarizer on the visual recognition side of the surface.

5. The virtual image display device according to any one of claims 1 to 3, wherein, The reflective circular polarizer is shaped into a curved surface.

Images