Reality extended display device

Abstract

Provided is a reality-extended display device that improves the presence of a display image. The present invention relates to a reality-extended display device capable of allowing a user to visually recognize a first image and a second image having different distances in a state in which a real environment is visually recognized, the reality-extended display device comprising: a display panel that emits polarized light for the first image and the second image; a plane-split polarized light conversion member disposed at a position at which the polarized light is incident; and an optical element and a concave half mirror disposed at a position at which the polarized light that has passed through the surface-divided polarized light conversion member is incident, the surface-divided polarized light conversion member having: a first transmissive portion that transmits the polarized light for the first image in a plan view, and a second transmissive portion that transmits the polarized light for the second image in a plan view; and a second transmissive section that transmits polarized light for a second image and generates a phase difference of [lambda] / 2 from the first transmissive section, the optical element causing a virtual image distance of a first image generated from the first polarized light transmitted through the first transmissive section to differ from a virtual image distance of a second image generated from the second polarized light transmitted through the second transmissive section.

Description

Technical Field

[0001] The following disclosure relates to an extended reality display device. Background Art

[0002] In recent years, research and development of augmented reality display devices that superimpose display images (also called "images") on the real world has been continuously developed. For example, a head-up display that displays images of information facing the driver on the windshield has been proposed. In such augmented reality display devices, in order to enhance the sense of presence, a three-dimensional image is sometimes used as an image superimposed on the real world.

[0003] As an existing technology related to three-dimensional display, for example, patent document 1 discloses a three-dimensional display method, which generates a two-dimensional image obtained by projecting a display object from the line of sight of an observer relative to a plurality of display surfaces arranged at different depth positions when observed from an observer, and displays the generated two-dimensional image on any two of the plurality of display surfaces respectively, so that the brightness of the displayed two-dimensional image varies independently on any two of the plurality of display surfaces to generate a three-dimensional stereoscopic image, and uses a polarization-type multi-focal optical system to image display light of the two-dimensional image on any two of the plurality of display surfaces, and controls the polarization direction of the display light so that the brightness of the two-dimensional image imaged on any two of the plurality of display surfaces varies independently. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2002-156603 Summary of the invention Technical Problems to be Solved by the Invention

[0005] Although the prior art described in Patent Document 1 can perform naked-eye three-dimensional display, it cannot be applied to an augmented reality display device.

[0006] The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide an extended reality display device that improves the sense of presence of displayed images. Technical solutions for solving technical problems

[0007] (1) An extended reality display device according to an embodiment of the present invention enables a user to visually recognize a first image and a second image at different distances while being able to visually recognize a real environment. The extended reality display device includes a display panel that emits polarized light for the first image and the second image; a surface-split polarized light conversion component that is arranged at a position where the polarized light is incident; and an optical element and a concave half mirror that are arranged at a position where the polarized light that has passed through the surface-split polarized light conversion component is incident. The surface-split polarized light conversion component includes: a first transmission portion that transmits the polarized light for the first image when viewed from above; and a second transmission portion that transmits the polarized light for the second image and produces a phase difference of λ / 2 compared to the first transmission portion, wherein the optical element causes a virtual image distance of a first image generated from the first polarized light that has passed through the first transmission portion to be different from a virtual image distance of a second image generated from the second polarized light that has passed through the second transmission portion.

[0008] (2) In addition, in an extended reality display device according to one embodiment of the present invention, based on the structure of (1) above, the first transmission part is a non-conversion part that transmits the polarized light for the first image without converting the polarization state, and the second transmission part is a conversion part that causes the polarized light for the second image to produce a phase difference of λ / 2 and convert the polarization state.

[0009] (3) In addition, in an extended reality display device according to an embodiment of the present invention, in addition to the configuration of (2) above, the conversion unit includes a resin layer having a λ / 2 phase difference.

[0010] (4) In addition, in an embodiment of the present invention, based on the structure of (1), (2) or (3) above, the second transmission portion has a pair of substrates and a liquid crystal layer arranged between the pair of substrates when observed in cross section, and the phase difference can be changed according to the voltage applied to the liquid crystal layer.

[0011] (5) In addition, in an extended reality display device according to one embodiment of the present invention, based on the structure of (1), (2), (3) or (4) above, the optical element is a liquid crystal lens, and the liquid crystal lens acts as a lens with a first focal length for the first polarized light, and does not act as a lens for the second polarized light, or acts as a lens with a second focal length.

[0012] (6) In addition, in an extended reality display device according to an embodiment of the present invention, in addition to the configuration of (5) above, the liquid crystal lens is a refractive lens, a distributed refractive index lens, or a diffractive lens.

[0013] (7) In addition, in an extended reality display device according to an embodiment of the present invention, in addition to the configuration of (5) above, the liquid crystal lens is a Pancharatnam-Berry phase lens.

[0014] (8) In an embodiment of the present invention, in addition to the configuration of (5), the liquid crystal lens includes a liquid crystal layer, and the focal length can be changed according to a voltage applied to the liquid crystal layer.

[0015] (9) In addition, a reality expansion type display device according to one embodiment of the present invention is based on the structure of (1), (2), (3), (4), (5), (6), (7) or (8) above, and the reality expansion type display device also has a polarization light selective reflection plate, which is arranged at the position where the polarized light that has passed through the surface-divided polarization light conversion component is incident.

[0016] (10) In addition, a reality expansion display device according to one embodiment of the present invention is based on the structure of (1), (2), (3), (4), (5), (6), (7), (8) or (9) above, and the reality expansion display device also has a combination of other surface-split polarization light conversion components and other liquid crystal lenses.

[0017] (11) In addition, the reality expansion display device of one embodiment of the present invention is based on the structure of the above-mentioned (1), (2), (3), (4), (5), (6), (7), (8), (9) or (10), and the display device is a head-mounted display device. Beneficial Effects

[0018] According to the present invention, it is possible to provide an extended reality display device that improves the sense of presence of displayed images. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A diagram for explaining the display principle of a virtual image in a display device. Figure 2 This is a diagram illustrating the display principle of conventional VR. Figure 3 It is a diagram that illustrates how people see real objects. Figure 4 It is a diagram for explaining a display state when there is only one virtual image plane. Figure 5 It is a diagram for explaining a display state when there are two virtual image planes. Figure 6 It is a side view schematically showing the structure of the extended reality display device according to the first embodiment. Figure 7 It is an enlarged cross-sectional view of the plane-divided polarization conversion member according to the first embodiment. Figure 8 The diagrams are for explaining the structure of a refractive lens using a resin, wherein the upper diagram is a cross-sectional view and the lower diagram is a plan view. Fig. 9 Yes Description Figure 8 The diagrams showing the operation of the refractive lens in orientation A show that the upper diagram shows when a voltage is applied to the liquid crystal layer, and the lower diagram shows when no voltage is applied to the liquid crystal layer. Fig.10 Yes Description Figure 8 The diagrams showing the operation of the refractive lens at the orientation B are shown in which the upper diagram shows when a voltage is applied to the liquid crystal layer, and the lower diagram shows when no voltage is applied to the liquid crystal layer. Fig.11 It is a top view illustrating the structure of the Pancharatnam-Berry phase lens. Fig.12 It is a diagram for explaining the function of the Pancharatnam-Berry phase lens. Fig.13 It is a side view schematically showing the structure of an extended reality display device according to the second embodiment. Fig.14 FIG. 1 is a side view schematically showing the structure of an extended reality display device according to a third embodiment. Fig.15 This is a side view schematically showing another example of the structure near the concave half mirror in the extended reality display device according to the third embodiment. Fig.16 : is an explanatory diagram showing an example of an image displayed by an extended reality display device, wherein the left side shows an original image and the right side shows an enlarged image. Fig.17 This is an explanatory diagram showing an example of a state in which a display image of an augmented reality display device installed in a car is superimposed on a real environment. Fig.18 It is a plan view schematically showing the structure of a plane-divided polarization conversion member included in the extended reality display device according to the fourth embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiments of the present invention will be described. The present invention is not limited to the contents described in the following embodiments, and design changes can be appropriately made within the scope of the configuration of the present invention. In addition, in the following description, for the same parts or parts with the same functions, the same figure numerals are appropriately used between different drawings, and the repeated descriptions are appropriately omitted. The various modes of the present invention can also be appropriately combined within the scope of not departing from the gist of the present invention.

[0021] The reality-enhanced display device of this embodiment enables a user to visually recognize a first image and a second image at different distances while visually recognizing a real environment. The type of the display device is not particularly limited, for example, it may be an AR display device that displays content corresponding to AR (augmented reality) technology, or a head-up display (Head-Up Display, abbreviated: HUD). The form of the above-mentioned display device is not particularly limited, and it may be, for example, a head-mounted display device (HMD). A head-mounted display device (HMD) is a display device that can be worn on the head, for example, in the shape of goggles that can be worn on the head, and when worn, a display such as a liquid crystal display is arranged in front of the user's eyes. Such an HMD is suitable for viewing content corresponding to AR (augmented reality) technology. As the structure of the HMD, for example, the following structure can be listed: a support portion for wearing on the user's head and a display with a liquid crystal module, and when worn, the display is arranged in front of the user's eyes.

[0022] The reality expansion display device of this embodiment has a surface-splitting polarized light conversion component, which can generate two images with different virtual image distances from one display panel. As a specific application example, in the case of an AR display device, images of a near view (nearby virtual image) and a distant view (distant virtual image) can be added to the real world. In this way, the sense of presence of the displayed image can be improved, thereby reducing the burden on the user (observer) during viewing and listening, and improving the sense of immersion in the content.

[0023] Figure 1 In the drawings of the present application, a dashed line indicates the direction of the line of sight of the user U, a solid arrow indicates the path of light that displays a real image toward the eyes of the user U, and a dotted arrow indicates the path of light that displays a virtual image toward the eyes of the user U. Figure 1 The display device includes a liquid crystal lens 50 with adjustable focal length, a lens (physical lens) 40 with fixed focal length, a polarizing plate 13, and a display 11 in order from the user U side. The distance from the liquid crystal lens 50 to the display 11 is short in a head mounted display device (HMD) or the like, so the user U visually recognizes a virtual image V behind the display 11. Here, if the focal length of the liquid crystal lens 50 is changed, the position of the virtual image V moves forward and backward relative to the user U. Whether the virtual image V moves intermittently or continuously depends on the method of the liquid crystal lens 50. However, in Figure 1 In the display device, the virtual image V at a specific timing is always formed at a specific distance. In other words, the virtual image V is displayed in one plane. Hereinafter, the plane displaying the virtual image V is also referred to as a "virtual image plane".

[0024] Next, the problems when using virtual images for display will be described based on a VR display device as a typical example of a display device that displays virtual images. VR motion sickness is known as the above problem, and its occurrence mechanism is as follows. Figure 2 This is a diagram illustrating the display principle of existing VR. Figure 2 As shown, in VR display, by separately displaying the image R for the right eye and the image L for the left eye, the user U visually recognizes that the image I1 exists at the position where the user wants to project the 3D image. Figure 3 It is a diagram that illustrates the state of a person viewing a real object. Figure 2 and Figure 3 By comparison, it can be seen that the difference between existing VR and the state of people viewing real objects is that the movement (convergence) of rotating the right eye RE and the left eye LE toward the image I1 and the focus adjustment are inconsistent. It is believed that VR motion sickness is caused by the difference between the focus adjustment distance (the distance between the image R for the right eye and the image L for the left eye) D1 and the distance D2 based on the gaze point of both eyes. This is caused by the fact that the image R for the right eye and the image L for the left eye are virtual images, and the virtual image plane (the distance of the virtual image) cannot move. Here, if the virtual image plane can be moved using a liquid crystal lens that can adjust the focal length, it can be achieved. Figure 3 state, which can prevent VR motion sickness.

[0025] On the other hand, when displaying a stereoscopic image (3D image) through VR, it is difficult to completely eliminate the discomfort when compared with the state in which a person sees a real object by simply moving the virtual image using a liquid crystal lens capable of adjusting the focal length. Figure 4 is a diagram for explaining a display state when there is only one virtual image surface. Figure 5 2 is a diagram illustrating the display state when there are two virtual image planes. When there is only one virtual image plane, how to express the object in the peripheral vision becomes a problem. Specifically, Figure 4 As shown in FIG. 1 , when the focus is on the position of image I1, the image I2 of the object located closer should be seen blurred. If there is only one virtual image plane, two blurred images I2a for the right eye and the left eye are displayed on the same virtual image plane. By making it look like there is a blurred image I2, it can be perceived as peripheral vision. However, when switching the viewpoint to the position of image I1 and the position of image I2, it is necessary to switch both the liquid crystal lens and the image. Since the blur is expressed by the image, it is difficult to completely eliminate the discomfort. In contrast, Figure 5 As shown, if there are two virtual image planes, there is no need to switch the liquid crystal lens and the image when the viewpoint is switched, so smooth viewpoint switching can be performed to obtain a good sense of immersion. Therefore, in the present invention, two virtual image planes (two images with different virtual image distances) are generated.

[0026] <First Embodiment> Figure 6 It is a side view schematically showing the structure of the reality expansion type display device of the first embodiment. The reality expansion type display device of the first embodiment is an AR display device. The AR display device uses a concave lens (concave half mirror) 60 or a light guide plate, etc. to overlap the image from the display 11 with the real environment for the user U to watch. The concave half mirror 60 transmits the ambient light to the user U side and reflects the image light from the display 11 to the user U side. The AR display device comprises, in sequence: a liquid crystal lens (optical element) 50 that is opposite to the reflection surface of the concave half mirror 60 and can adjust the focal length, a surface-split polarized light conversion component 20, a polarizing plate 13 and a display 11.

[0027] The display panel 10 composed of the display 11 and the polarizing plate 13 emits polarized light. When one of the two images with different virtual image distances is defined as a "first image" and the other image is defined as a "second image", the display panel emits polarized light for the first image and the second image, respectively. The polarized light transmission surface for the first and second images is divided into the polarized light conversion component 20 and enters the liquid crystal lens 50 capable of adjusting the focal length.

[0028] As the display 11, for example, a self-luminous display such as a liquid crystal display (LCD) or an organic EL display (OLED) can be cited. As the polarizing plate 13, a linear polarizer is used that transmits polarized light vibrating in a certain direction (a first polarized light component) and absorbs or reflects polarized light vibrating in a direction orthogonal to the polarized light (a second polarized light component).

[0029] The above-mentioned plane-divided polarization conversion member 20 has a first transmission portion that transmits polarized light for a first image and a second transmission portion that transmits polarized light for a second image in a plan view. The second transmission portion is a region that generates a phase difference of λ / 2 compared with the first transmission portion, and the polarized light for the first image is transmitted through the first transmission portion, and the polarized light for the second image is transmitted through the second transmission portion, so that the polarized light for the first image and the polarized light for the second image can generate a phase difference of λ / 2. Figure 6The display device can make the virtual image distances of two images different by utilizing the phase difference of λ / 2. Here, "generating a phase difference of λ / 2" means giving a phase difference equivalent to 1 / 2 of the wavelength to the transmitted light, for example, giving a phase difference of 200nm or more and 350nm or less to the light of wavelength 550nm. In the present embodiment, the above-mentioned surface-divided polarization conversion component 20 is a non-conversion part 22 that allows the first transmission part to transmit the polarized light for the first image without converting the polarization state, and the second transmission part is a conversion part 21 that converts the polarization state by generating a phase difference of λ / 2 for the polarized light for the second image. Here, "not converting the polarization state" means, for example, that the phase difference with respect to the light of wavelength 550nm is less than 10nm.

[0030] As the plane-divided polarization conversion member 20, a member that can variably form two or more portions whose phase difference is different from each other by λ / 2 in a plane parallel to the display surface of the display 11 can be used, and for example, a liquid crystal panel can be used. That is, in the plane-divided polarization conversion member 20, when viewed in cross section, the conversion section (second transmission section) 21 includes a pair of substrates and a liquid crystal layer disposed between the pair of substrates, and the phase difference can also be changed by applying a voltage to the liquid crystal layer. In the mode of variably forming two or more portions whose phase difference is different from each other by λ / 2, the arrangement of the conversion section (second transmission section) 21 and the non-conversion section (first transmission section) 22 in the plane can be switched on / off in time. Specifically, by applying a voltage to the liquid crystal layer, the portion that is the conversion section 21 at a certain time becomes the non-conversion section 22, and the portion that is the non-conversion section 22 at a certain time becomes the conversion section 21. Therefore, it is preferable that the entire plane-divided polarization conversion member 20 is a liquid crystal panel.

[0031] Figure 7 This is an enlarged cross-sectional view of the plane-split polarization conversion component of the first embodiment. On the screen of the display 11, there is a plane-split polarization conversion component (liquid crystal panel) 20 that can switch the presence or absence of a phase difference of λ / 2 (i.e., 275nm relative to 550nm light). As the liquid crystal mode of the liquid crystal panel, the TN mode, VA mode, ECB mode, IPS mode, FFS mode and other modes generally used in liquid crystal panels can be applied. If the VA mode is taken as an example, it can be configured so that the voltage is disconnected and no phase difference is generated, and the voltage is turned on and a phase difference of λ / 2 is generated. In addition, in order to reduce the wavelength dependence, the plane-split polarization conversion component 20 can also be stacked in two layers of liquid crystal panels.

[0032] like Figure 7As shown, the plane-divided polarization conversion component (liquid crystal panel) 20 can drive the liquid crystal 26a in the liquid crystal layer 26 for each region by applying a voltage to the liquid crystal layer 26 sandwiched by a pair of substrates 25. The number of regions of the liquid crystal panel constituting the plane-divided polarization conversion component 20 can be the same as the number of pixels of the display 11 arranged in an overlapping manner, or it can be less than the number of pixels of the display 11. Figure 7 In the figure, regarding the VA mode liquid crystal panel, the voltage-on state is shown at the top, and the voltage-off state is shown at the bottom. The linearly polarized light emitted from the display 11 does not change its phase in the plane-divided polarization conversion member 20 in the voltage-off state, and therefore is transmitted in the state of linearly polarized light. Although the orientation of the liquid crystal lens 50 is not limited, the case where the liquid crystal lens 50 is configured so as not to function as a lens is described here. In this case, the transmitted light directly reaches the human eye from the display, so the screen of the display 11 is directly seen (real image is seen).

[0033] On the other hand, when the voltage of the plane-divided polarization conversion component 20 is turned on, the light emitted from the display 11 becomes linear polarization light rotated by 90 degrees. In this way, when the linear polarization light passes through, the liquid crystal lens 50 functions as a lens. Since the display 11 is placed at a distance equal to the focal length of the liquid crystal lens 50, it becomes approximately parallel light through the lens action and reaches the eyes of the user U. Therefore, the user U sees that the display 11 is approximately at infinity (can see a virtual image). In this way, since the real image and the virtual image can be switched by the plane splitting polarization conversion member 20, two virtual image planes at different distances can be simultaneously observed by plane splitting, and a display with depth (3D display) can be seen. For example, only the display area of ​​the character to be the foreground can be set as the non-conversion section 22 (the area with zero phase difference), and the background area to be the background can be set as the conversion section 21 (the area with λ / 2 phase difference).

[0034] In the above configuration, for simplicity, the display 11 is placed at the focal length so that the virtual image is infinitely far away, but the virtual image can be arranged at any location by changing the focal length of the liquid crystal lens 50 or the distance from the liquid crystal lens 50 to the display 11. The focal length of the liquid crystal lens 50 can be adjusted by voltage, so by increasing the voltage applied to the liquid crystal lens 50, the virtual image distance can be moved from infinitely far away to close.

[0035] In addition, as the above-mentioned plane-divided polarization conversion member 20, a member that stably has two or more parts with phase differences that differ from each other by λ / 2 in a plane parallel to the display surface of the display 11 can be used. For example, a member that is plane-divided in such a manner that the above-mentioned non-conversion portion 22 is a transparent member and the above-mentioned conversion portion 21 is a λ / 2 plate can be used. The λ / 2 plate is a member that gives a phase difference equivalent to 1 / 2 of the wavelength of visible light, for example, a member that gives a phase difference of 200nm to 350nm to light with a wavelength of 550nm. When the λ / 2 plate is used, the arrangement of the above-mentioned conversion portion (second transmission portion) 21 and the above-mentioned non-conversion portion (first transmission portion) 22 in the plane is not switched (ON / OFF). The above-mentioned surface-divided component can be produced, for example, by the following method: after a resin film having a λ / 2 phase difference is attached to the entire surface of a supporting component such as a glass substrate, the resin film is patterned in such a manner that the resin film is arranged on the above-mentioned conversion portion 21 to form a resin layer. Alternatively, it can also be produced by a method in which a resin layer is formed by attaching a resin film having a λ / 2 phase difference only to the region of the supporting component corresponding to the conversion portion 21. In addition, instead of using a resin film having a λ / 2 phase difference to form a resin layer having a λ / 2 phase difference on a supporting component, for example, an alignment film can be formed on the supporting component, a layer composed of a photopolymerizable liquid crystal material is formed on the alignment film, and the photopolymerizable liquid crystal material is solidified to form a resin layer.

[0036] At the position where the polarized light passing through the plane-split polarization conversion member 20 is incident, an optical element is arranged so that the virtual image distance of the first image generated from the first polarized light passing through the non-conversion section (first transmission section) 22 and the virtual image distance of the second image generated from the second polarized light passing through the conversion section (second transmission section) 21 are different. As such an optical element, in the present embodiment, a liquid crystal lens 50 capable of adjusting the focal length is provided. The liquid crystal lens 50 functions as a lens having a first focal length for the first polarized light, and does not function as a lens (does not bend light) or functions as a lens having a second focal length for the second polarized light. For example, when the vibration direction of the polarized light emitted from the display panel 10 coincides with the direction in which the liquid crystal lens 50 functions, the first polarized light passing through the non-conversion section 22 will observe a virtual image V, and the second polarized light switched to polarized light by the conversion section 21, whose vibration direction is orthogonal by 90 degrees, will observe a real image (display screen of the display panel) because the liquid crystal lens 50 does not function. Thus, two virtual image distances (including a case where one of them becomes a real image) can be realized using one display panel, and smooth viewpoint switching including the above-mentioned peripheral vision can be realized. In addition, if the liquid crystal lens 50 is applied to the ambient light, the magnification is different between the position where the lens is applied and the position where the lens is not applied, so two images of different sizes are seen. Therefore, the liquid crystal lens 50 is placed in a position where the ambient light does not pass, and a concave half mirror 60 is arranged on the user U side of the optical path of the liquid crystal lens 50.

[0037] The type of the above-mentioned liquid crystal lens 50 is not particularly limited, and examples thereof include a refractive lens, a refractive index distribution type (GRIN) lens, a diffractive lens, and the like. In addition, the above-mentioned refractive index distribution type (GRIN) lens is a lens that bends light by the orientation of liquid crystal. These liquid crystal lenses generally act as lenses for linear polarization in one vibration direction, but have no lens effect on linear polarization in another vibration direction. In addition, when the liquid crystal material is a solidified type, the focal length of the liquid crystal lens is fixed. On the other hand, when the liquid crystal material is movable, the focal length of the lens can be changed. Regarding the method of controlling the focal length, the refractive lens can be controlled by voltage, the refractive index distribution type lens can be controlled by both voltage and period, and the diffractive lens can be controlled by period. As the above-mentioned liquid crystal lens, it is preferred to have a liquid crystal layer and a lens whose focal length can be changed according to the voltage applied to the above-mentioned liquid crystal layer.

[0038] Reference Figures 8 to 10 The above-mentioned refractive lens will be described. Figure 8 The diagrams are for explaining the structure of a refractive lens using a resin, with the upper diagram being a cross-sectional view and the lower diagram being a plan view. Fig. 9 Yes Description Figure 8 The diagrams showing the operation of the refractive lens in orientation A show that the upper diagram shows when a voltage is applied to the liquid crystal layer, and the lower diagram shows when no voltage is applied to the liquid crystal layer. Fig.10 Yes Description Figure 8 The diagrams showing the operation of the refractive lens in orientation B show that the upper diagram shows when a voltage is applied to the liquid crystal layer, and the lower diagram shows when no voltage is applied to the liquid crystal layer. Fig. 9 and Fig.10 The arrows in FIG. 1 represent the paths of light passing through the refractive lens. The refractive lens has a structure in which a glass substrate 51, a resin Fresnel lens 52, an electrode 53, a liquid crystal layer 54, an electrode 53, and a glass substrate 51 are stacked. For example, when the liquid crystal layer 54 uses positive liquid crystal 54a (the major axis of the refractive index ellipsoid of the liquid crystal is along the electric field), when no voltage is applied, the liquid crystal 54a is horizontally oriented ( Fig. 9 and Fig.10 ), when voltage is applied, the liquid crystal 54a is vertically oriented ( Fig. 9 and Fig.10). The combination of the refractive indexes of the resin and the liquid crystal 54a constituting the Fresnel lens 52 is not limited. For example, the refractive index of the resin is about 1.5, and the ne (refractive index on the long axis side) and no (refractive index on the short axis side) of the liquid crystal 54a are 1.8 and 1.5, respectively. Fig. 9 As shown, in orientation A, when no voltage is applied, there is a refractive difference, so the light is bent, and when a voltage is applied, the refractive difference disappears, so the light is not bent. Fig.10 As shown, in the orientation B, no refractive difference occurs when no voltage is applied or when a voltage is applied, and the lens function is never generated.

[0039] The above-mentioned liquid crystal lens 50 can also be a Pancharatnam-Berry Phase lens. The Pancharatnam-Berry Phase lens is a liquid crystal lens that switches divergence and convergence according to the direction of circularly polarized light (for example, refer to U.S. Patent No. 10379419). For example, it functions as a lens that switches the focal length to f and -f using left circularly polarized light and right circularly polarized light. The focal length f only needs to be (Active), and in principle it can be controlled periodically. In this embodiment, by adding a fixed lens with a focal length of f, the switching distance of the focal length can be adjusted. Therefore, for example, if a fixed lens with a focal length of f is added, the focal length can be switched between f / 2 and 0. In addition, circularly polarized light can be achieved by adding a λ / 4 plate to linearly polarized light. Therefore, by adjusting the intensity of the separately provided lens with a configuration that is almost the same as that of linearly polarized light, almost the same effect can be achieved.

[0040] Fig.11 A top view illustrating the construction of a Pancharatnam-Berry phase lens. Fig.12 This is a diagram for explaining the function of the Pancharatnam-Berry phase lens. The Pancharatnam-Berry phase lens uses the Pancharatnam-Berry phase (PB orientation) and Fig.11 The periodic orientation of the liquid crystal 54a shown produces diffraction, thereby achieving a lens function. Fig.12 middle, Fig.12 The solid line in the figure represents the optical path of the right circularly polarized light RCP emitted from the Pancharatnam-Berry phase lens PBL. Fig.12 The dotted line in FIG. 5 represents the optical path of the left circularly polarized light LCP emitted from the Pancharatnam-Berry phase lens PBL. Fig.12 The Pancharatnam-Berry phase lens PBL shows an example in which when the incident circularly polarized light is right circularly polarized light RCP, it converges, and when it is left circularly polarized light LCP, it diverges, and the direction of the circularly polarized light at the time of emission becomes the opposite direction. In this way, the Pancharatnam-Berry phase lens can switch the divergence and focusing of the focal point f by switching the direction of the incident circularly polarized light.

[0041] The Pancharatnam-Berry phase lens (PB lens) is a lens that can switch the intensity of the refraction based on the lens (convex-concave lens), and in principle can be actively switched on and off. That is, if the orientation spacing of the liquid crystal is adjusted, the intensity of the lens can be adjusted. When the PB lens is used, in order to make the light emitted from the display 11 circularly polarized light, for example, the polarizing plate 13 is a circular polarizing plate composed of a combination of a linear polarizing plate and a λ / 4 plate. By placing a surface-divided polarization conversion component 20 that can switch the circularly polarized light to the opposite circularly polarized light on the circularly polarizing plate, the left and right circularly polarized light can be switched.

[0042] According to the extended reality display device of this embodiment, two virtual image planes can be switched using the plane splitting polarization conversion component 20. Thus, two planes at different distances can be observed simultaneously by plane splitting, and a display with depth (3D display) can be performed, thereby improving the immersion of AR and smoothly switching viewpoints.

[0043] <Second Embodiment> Fig.13 : is a side view schematically showing the structure of the reality expansion type display device of the second embodiment. The reality expansion type display device of the second embodiment is an AR display device having an optical system called the so-called birdbath method. By configuring a polarized light selective reflection plate 61 between the liquid crystal lens 50 and the concave half-reflecting mirror 60, both the light utilization efficiency and the image are difficult to deform are ensured. In this structure, the distance of the virtual image can also be switched by the liquid crystal lens 50, but by changing the curvature of the concave half-reflecting mirror 60 arranged in front of the user U and the concave mirror 62 arranged below the eyes of the user U, the distance of each virtual image V can also be changed. A λ / 4 plate 63 is arranged on the surface of the concave half-reflecting mirror 60 and the concave mirror 62 opposite to the polarized light selective reflection plate 61.

[0044] In addition, Fig.13 In the configuration, even if the liquid crystal lens 50 is removed and the curvature of the concave mirror 62 is made different, two virtual image distances can be realized simultaneously.

[0045] <Third Embodiment> The third embodiment of the reality-enhanced display device is a head-up display (HUD). The head-up display generally uses a semi-transmissive surface (mostly a spherical surface or a free-form surface close to a spherical surface) called a windshield or assembly to overlap the image from the display with the real environment. Fig.141 is a side view schematically showing the structure of an extended reality display device according to the third embodiment, and shows the structure of an optical system facing the HUD using the windshield of a passenger car. Since the windshield 80 is a curved surface close to a sphere, it has the effect of slightly magnifying the image, but this alone is not enough, so generally a concave mirror 62 is provided on the incident side thereof, and the original image is magnified by the combination of the two. Some positions for placing the liquid crystal lens 50 are considered, but since the distance of the virtual image is determined by magnifying the optical distance and the liquid crystal lens 50 does not overlap with the ambient light (the ambient light is also magnified), it is preferably located between the windshield 80 and the concave mirror 62 or near the concave mirror 62. Alternatively, the liquid crystal lens 50 may be arranged in front of the concave mirror 62, and the lens power of the liquid crystal lens 50 may be used at about twice the level. In this case, if Figure 8 In the case of a refractive liquid crystal lens such as that shown in FIG. 1 , the lens power varies according to the linear polarization light, so that the lens power can be directly increased by about 2 times. However, for example, Fig.11 In the case of a PB lens type as shown in FIG. 1 , if the change in the direction of circularly polarized light is taken into consideration, then Fig.15 As shown, a λ / 4 plate 63 is provided. Fig.15 This is a side view schematically showing another example of the structure near the concave half mirror in the extended reality display device according to the third embodiment. With this structure, by dividing the area into an area with a phase difference of λ / 2 and an area with a phase difference of zero (when using a PB lens, it is divided into an area with a phase difference of λ / 4 and an area with an axially orthogonal phase difference of λ / 4), virtual images like virtual images V1 and V2 appear to float at other distances, so that the virtual image distance can be used in a manner corresponding to the situation (differentiated use).

[0046] <Fourth Embodiment> Fig.16 : is an explanatory diagram showing an example of an image displayed by an extended reality display device, wherein the left side shows an original image and the right side shows an enlarged image. Fig.17 This is an explanatory diagram showing an example of a state where a display image of an augmented reality display device installed in a car is superimposed on a real environment. Since the augmented reality display device displays an image superimposed on the real environment, it has the following display characteristics. (1) Fig.16 As shown, in a display using an extended reality display device, a portion where an image is not reflected (a portion where a black display is performed) tends to become larger. (2) Fig.17 As shown, in the display based on the reality expansion display device, the lower side of the screen is close to the virtual image distance, and the upper side of the screen is far from the virtual image distance, and it is easy to superimpose images in the real environment. Fig.17In the example, an AR image superimposed on the real environment is displayed on the upper side of the screen as a virtual image V3 on the back side. An AR image generated in accordance with the behavior of the vehicle is displayed in the center of the screen as a first near virtual image V4. On the lower side of the screen, an AR image of an instrument or the like is displayed as a second near virtual image V5.

[0047] According to the above features, in an extended reality display device, it is envisioned that the upper side of the screen fixes the virtual image to the back side, the lower side of the screen fixes the virtual image to the front side, and the virtual image distance (virtual image position) is switched only in a part of the screen. In this case, at least a part of the surface-divided polarization conversion component is formed by a liquid crystal panel, thereby enabling the virtual image position to be switched, and at least a part of the other part is formed by a phase difference plate, and the phase is shifted by λ / 2, thereby enabling the part where the virtual image distance is switched to the back side and the front side and the part where the virtual image distance is fixed to be set separately.

[0048] Fig.18 FIG. 1 is a top view schematically showing the structure of a plane-split polarization conversion component included in an extended reality display device according to a fourth embodiment. Fig.18 As shown, the plane-divided polarization conversion member 120 has a first transmission section 121 that transmits polarized light for a first image, a second transmission section 122 that transmits polarized light for a second image, and a third transmission section 123 that transmits polarized light for a third image in a plan view. No phase difference plate is provided in the first transmission section 121, a liquid crystal panel is provided in the second transmission section 122, and a phase difference plate is provided in the third transmission section 123. Fig.18 The structure of the plane-divided polarization conversion component 120 corresponds to the division example of the display screen of the augmented reality display device. That is, the first transmission part 121 corresponds to the upper side of the screen where the virtual image is fixed to the back side, the second transmission part 122 corresponds to the center of the screen where the virtual image distance (virtual image position) is switched, and the third transmission part 123 corresponds to the lower side of the screen where the virtual image is fixed to the front side.

[0049] The third transmission section 123 can be formed cheaply by laminating a phase difference plate. On the other hand, the liquid crystal panel constituting the second transmission section 122 can also be enlarged, and the third transmission section 123 is also composed of a liquid crystal panel. As the liquid crystal panel, it is preferred to use a liquid crystal panel that uses liquid crystals that are horizontally oriented without applying a voltage. In any case, since the first transmission section 121 does not require the configuration of a liquid crystal panel or a phase difference plate, the surface-divided polarization conversion component 120 of the fourth embodiment can be manufactured cheaply compared to the surface-divided polarization conversion component that can switch the virtual image distance of the entire surface of the screen.

[0050] Modification 1 The reality expansion display device of the first embodiment and the second embodiment uses a set of surface-split polarization conversion components and liquid crystal lenses, but may also have multiple sets of surface-split polarization conversion components 20 and liquid crystal lenses 50. By using multiple sets (N sets), a virtual image surface of 2N faces can be generated. However, the driving, image processing described later, etc. become complicated. In principle, the surface-split polarization conversion component 20 is preferably close to the display surface. This is because the boundary surface of the virtual image V is accurately defined on the display image. If the surface-split polarization conversion component 20 is separated from the display surface, the pixels of the boundary portion may be included in any one of the two virtual image surfaces. The problem of the boundary portion can be dealt with by using the image processing described later. In this way, if a combination of multiple surface-split polarization light conversion components 20 and liquid crystal lenses 50 is used, 2N virtual image planes can be switched, 2N planes at different distances due to surface division can be seen at the same time, a display with depth (3D display) can be viewed, and as a VR, the sense of immersion is improved and smooth viewpoint switching can be performed.

[0051] <Modification 2> In the above embodiment, a voltage-variable liquid crystal lens is used, but a static (non-variable) liquid crystal lens 50 may be used using a UV-curable liquid crystal material. In this case, since a static liquid crystal lens 50 is used, the virtual image V cannot be moved by voltage, but the two virtual images (including the shell of the real image) V can be switched by the plane-divided polarization conversion component 20. It can be manufactured at low cost, and the liquid crystal lens 50 does not require electrical wiring, and has the advantage that the electrical wiring is concentrated on the display 11 side. Description of Reference Numerals

[0052] 10: Display Panel 11: Display 13: Polarizing plate 20, 120: Surface split polarization conversion component 21: Conversion Department 22: Non-conversion part 25: Substrate 26: Liquid crystal layer 26a: LCD 40: Lens (physical lens) 50: Liquid crystal lens 51: Glass substrate 52: Fresnel lens 53: Electrode 54: Liquid crystal layer 54a: LCD 60: Concave half mirror 61: Polarized light selective reflector 62: Concave mirror 63: λ / 4 plate 64: Reflector 80: Windshield 121: First transmission part 122: Second transmission part 123: Third transmission part D1: Focus adjustment distance D2: Convergence distance I1, I2: 3D images I2a: Blurred Image R: Image for the right eye RCP: Right Circular Polarization RE: Right Eye L: Image for the left eye LCP: Left Circularly Polarized Light LE: Left Eye U:User (Observer) V, V1, V2: Virtual image V3: Virtual image on the inside V4: First Near Virtual Image V5: The second closest virtual image

Claims

1. An extended reality display device, which enables a user to visually recognize a first image and a second image at different distances while being able to visually recognize a real environment, wherein the extended reality display device is characterized in that: include: A display panel that emits polarized light for the first image and the second image; a plane-divided polarization conversion member disposed at a position where the polarized light is incident; and The optical element and the concave half mirror are arranged at a position where the polarized light passing through the plane-divided polarization conversion member is incident. The plane-divided polarization conversion component comprises: A first transmission portion that transmits polarized light for a first image in a plan view; and a second transmission portion that transmits polarized light for a second image and generates a phase difference of λ / 2 compared with the first transmission portion; The optical element makes a virtual image distance of a first image generated from first polarized light transmitted through the first transmission portion different from a virtual image distance of a second image generated from second polarized light transmitted through the second transmission portion.

2. The extended reality display device according to claim 1, It is characterized in that The first transmission part is a non-conversion part that transmits the polarized light for the first image without converting the polarization state. The second transmission section is a conversion section that generates a phase difference of λ / 2 in the polarized light for the second image and converts the polarization state.

3. The extended reality display device according to claim 2, It is characterized in that The conversion portion includes a resin layer having a λ / 2 phase difference.

4. The extended reality display device according to claim 1, It is characterized in that When viewed in cross section, the second transmission portion includes a pair of substrates and a liquid crystal layer disposed between the pair of substrates. The phase difference can be changed according to a voltage applied to the liquid crystal layer.

5. The extended reality display device according to claim 1, It is characterized in that The optical element is a liquid crystal lens, The liquid crystal lens functions as a lens having a first focal length for the first polarized light, and does not function as a lens for the second polarized light, or functions as a lens having a second focal length.

6. The extended reality display device according to claim 5, It is characterized in that The liquid crystal lens is a refractive lens, a distributed refractive index lens or a diffractive lens.

7. The extended reality display device according to claim 5, It is characterized in that The liquid crystal lens is a Pancharatnam-Berry phase lens.

8. The extended reality display device according to claim 5, It is characterized in that The liquid crystal lens includes a liquid crystal layer, and the focal length can be changed according to a voltage applied to the liquid crystal layer.

9. The extended reality display device according to claim 1, It is characterized in that The extended reality display device further includes a polarization selective reflection plate disposed at a position where the polarized light that has passed through the plane-divided polarization conversion member is incident.

10. The extended reality display device according to claim 1, It is characterized in that The extended reality display device further includes a combination of other plane-split polarization conversion components and other liquid crystal lenses.

11. The extended reality display device according to claim 1, It is characterized in that The display device is a head-mounted display device.

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