Virtual image display device and optical unit

Abstract

To display virtual images at a plurality of positions in a depth direction at a time.SOLUTION: A virtual image display device 100A (100B) comprises: a display 11 that performs spatial fragmentation of video light ML corresponding to a first image PP1 and video light ML corresponding to a second image PP2, and alternately emits the rays of video light in a spatial manner or alternately emits the rays of video light in a temporal manner; a polarized light conversion device 23 that is arranged opposite to the display 11, and converts the video light ML corresponding to the first image PP1 into first circularly polarized light C1 and converts the video light ML corresponding to the second image PP2 into second circularly polarized light C2; a polarization diffraction lens 24 that has a positive power to the first circularly polarized light C1 corresponding to linearly polarized light in a first polarization direction D1, and has a negative power to the second circularly polarized light C2 corresponding to linearly polarized light in a second polarization direction D2; and an image forming lens 25 that has a positive power, and forms a virtual image with the video light ML passing through the polarization diffraction lens 24.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a virtual image display device and an optical unit that enable the observation of a virtual image, and more particularly to a virtual image display device that simultaneously shows images at different focal points. [Background technology]

[0002] A known head-mounted display device has a display device and multiple optical elements whose focal length changes depending on the power supply state, and a drive mechanism that moves at least one of them in the optical axis direction in order to move the virtual image position in the depth direction (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-135728 Summary of the Invention [Problem to be solved by the invention]

[0004] The head-mounted display device described in Patent Document 1 can display virtual images at different depth positions, but it only moves the virtual image between specific positions using a drive mechanism and cannot display virtual images at multiple depth positions at once. In other words, the position of the virtual image needs to be adjusted every time the user's gaze position changes. [Means for solving the problem]

[0005] A virtual image display device and optical unit in one aspect of the present invention comprises a display that spatially subdivides image light corresponding to a first image and a second image and emits the image light alternately spatially or alternately in time, and a virtual image optical system that is arranged on the light emission side of the display and has a polarized diffractive lens that has positive power for a first circularly polarized light and negative power for a second circularly polarized light, and an imaging lens that has positive power, and the virtual image optical system forms virtual images of the first image and the second image at different positions by making the image light corresponding to the first image incident on the polarized diffractive lens as the first circularly polarized light and making the image light corresponding to the two images incident on the polarized diffractive lens as the second circularly polarized light. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 2 is a front view of the appearance illustrating the wearing state of the virtual image display device of the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view illustrating the structure of the virtual image display device. [Figure 3] FIG. 2 is a diagram illustrating a display and a deflector. [Figure 4] FIG. 1 is a conceptual perspective view illustrating the function of a polarized diffractive lens. [Figure 5] 3 is a conceptual diagram illustrating a virtual image formed by the first virtual image display device. FIG. [Figure 6] FIG. 3 is a conceptual diagram illustrating an image processed by the first virtual image display device. [Figure 7] 4A and 4B are diagrams illustrating the convergence angle between the first virtual image display device and the second virtual image display device. [Figure 8] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a second embodiment. [Figure 9] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a third embodiment. [Figure 10] FIG. 10 is a side cross-sectional view illustrating a virtual image display device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] [First embodiment] A first embodiment of a virtual image display device according to the present invention will be described below with reference to FIGS.

[0008] FIG. 1 is a front view illustrating a state in which a head-mounted display, i.e., a head-mounted display device 200, is worn. The head-mounted display device (hereinafter also referred to as HMD) 200 allows an observer or wearer US wearing it to recognize an image as a virtual image. In FIG. 1 and other figures, X, Y, and Z are Cartesian coordinate systems, with the +X direction corresponding to the lateral direction in which the eyes EY of the observer or wearer US wearing the HMD 200 are aligned, the +Y direction corresponding to the upward direction perpendicular to the lateral direction in which the eyes EY are aligned for the wearer US, and the +Z direction corresponding to the forward direction or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0009] The HMD 200 includes a first virtual image display device 100A for the right eye, a second virtual image display device 100B for the left eye, a pair of temples 100C that support the virtual image display devices 100A and 100B, and a user terminal 90 that is an information terminal. The first virtual image display device 100A is composed of a first display driver 102a disposed on the upper part and a first transmission type mirror 103a that covers the front of the eyes. The second virtual image display device 100B is composed of a second display driver 102b disposed on the upper part and a second transmission type mirror 103b that covers the front of the eyes. The HMD 200, which combines the first virtual image display device 100A and the second virtual image display device 100B, can also be considered a virtual image display device in a broad sense. The pair of temples 100C are a mounting member or support device 106 that is mounted on the head of the wearer US, and support the upper ends of the pair of transmission type mirrors 103a, 103b via display drive units 102a, 102b that appear integrated in appearance. The combination of the pair of display drive units 102a, 102b is called the drive unit 102.

[0010] 2 is a side view illustrating the structure of the imaging system and other components incorporated in the first display driver 102a. The first display driver 102a includes a display 11, a polarization conversion device 23, a polarizing diffraction lens 24, an imaging lens 25, and a display control device 88. Of the components of the first display driver 102a, the combination of the polarization conversion device 23, the polarizing diffraction lens 24, and the imaging lens 25 is referred to as the virtual image optical system 20a. The combination of the virtual image optical system 20a and the first transmissive mirror 103a is referred to as the imaging optical system 20b.

[0011] The display 11 is a self-luminous image light generating device that generates moving or still images on a display surface 11d. The display 11, which will be described in detail later, spatially subdivides and spatially alternately emits video light ML1 and ML2 corresponding to a first image and a second image. The display 11 is, for example, an organic electroluminescence (EL) display that generates a monochrome still or moving image, for example, green, on the two-dimensional display surface 11d. The display 11 is driven by a display control device 88 to perform display operations. The display 11 is not limited to an organic EL display, but can be replaced with a display device using an inorganic EL, an organic LED, an LED array, a laser array, a quantum dot light-emitting element, or the like. The display 11 is not limited to a self-luminous image light generating device, but may also be configured with an LCD or other light modulation element, and form an image by illuminating the light modulation element with a light source such as a backlight.

[0012] FIG. 3 is a diagram illustrating the structure of optical elements incorporated in the first display driver 102a. In FIG. 3, area AR1 illustrates the display 11, and area AR2 illustrates the polarizing plate 23a, which will be described later. The display surface 11d of the display 11 has a large number of pixels PX arranged two-dimensionally in a matrix. Each pixel PX includes, for example, three-color sub-pixels PXs(R), PXs(G), and PXs(B). These sub-pixels PXs(R), PXs(G), and PXs(B) are arranged in a Bayer pattern, but this is not limiting and they may also be arranged in a stripe pattern, for example. The display surface 11d spatially alternates between a large number of elements E1 constituting a first image and a large number of elements E2 constituting a second image. The image light emitted from the large number of elements E1 collectively constitutes a first image light ML1 corresponding to the first image, and the image light emitted from the large number of elements E2 collectively constitutes a second image light ML2 corresponding to the second image (see FIG. 2). Here, the first image made up of a large number of elements E1 is, for example, an image to be projected far away and corresponds to a virtual image IM1, and the second image made up of a large number of elements E2 is, for example, an image to be projected near away and corresponds to a virtual image IM2 (see FIG. 2). The first image and the second image will be described in detail later with reference to FIG. 6, etc. Each element E1, E2 corresponds to a pixel PX. Each element E1, E2 is arranged alternately in a checkerboard pattern.

[0013] The display 11 is not limited to a color display, and may be a monochrome display such as green. When the display 11 displays a color display, the size of the images of each color may be different from the viewpoint of correcting horizontal chromatic aberration.

[0014] 2, the polarization conversion device 23 is disposed opposite the display 11, and converts the first video light ML1 corresponding to the first image into a first circularly polarized light C1, and converts the second video light ML2 corresponding to the second image into a second circularly polarized light C2. The polarization conversion device 23 has, in order from the display 11, a polarizing plate 23a and a quarter-wave plate 23b. Here, the polarizing plate 23a, which will be described in detail later, is formed by two-dimensionally arranging a large number of polarizing elements set in a first direction and a second direction that are orthogonal to each other.

[0015] Referring to FIG. 3, the polarizing plate 23a has a large number of polarizing elements PO arranged two-dimensionally in a matrix. Each polarizing element PO is either a first polarizing element PO1 with a first polarization direction D1 or a second polarizing element PO2 with a second polarization direction D2. In this embodiment, the first polarizing elements PO1 with the first polarization direction D1 and the polarizing elements PO2 with the second polarization direction D2 are arranged alternately in a checkerboard pattern in the polarizing plate 23a. Here, the first polarization direction D1 is based on the display surface 11d of the display 11 and is parallel to the Z direction. The second polarization direction D2 is parallel to the X direction.

[0016] 2, the quarter-wave plate 23b is a crystal or the like having an optical axis between the X direction perpendicular to the optical axis AX and the Z direction. The quarter-wave plate 23b causes the first linearly polarized light P1 that has passed through the first polarizing element PO1 (see FIG. 3) in the first polarization direction D1 of the polarizing plate 23a to be incident on the polarizing diffraction lens 24 as first circularly polarized light C1, and causes the second linearly polarized light P2 that has passed through the second polarizing element PO2 (see FIG. 3) in the second polarization direction D2 of the polarizing plate 23a to be incident on the polarizing diffraction lens 24 as second circularly polarized light C2.

[0017] Figure 4 is a diagram explaining the function of the polarized diffractive lens 24 shown in Figure 2. In Figure 4, the first region BR1 shows a first operational example of the first-type polarized diffractive lens GP1, and the second region BR2 shows a second operational example of the first-type polarized diffractive lens GP1. In Figure 4, the third region BR3 shows a first operational example of the second-type polarized diffractive lens GP2, and the fourth region BR4 shows a second operational example of the second-type polarized diffractive lens GP2. The polarized diffractive lens 24 shown in Figure 2 is the first-type polarized diffractive lens GP1.

[0018] When collimated left-handed circularly polarized light (LCP) such as the ray L1 shown by the solid line is incident on the polarized diffractive lens GP1 from the left side of the drawing, the polarized diffractive lens GP1 converts the left-handed circularly polarized light (LCP) into right-handed circularly polarized light (RCP) and converges it to focus or converge at the focal point FP. When collimated right-handed circularly polarized light (RCP) such as the ray L1 shown by the solid line is incident on the polarized diffractive lens GP1 from the left side of the drawing, the polarized diffractive lens GP1 converts the right-handed circularly polarized light (RCP) into left-handed circularly polarized light (LCP) and diverges it. When left-handed circularly polarized light (LCP) diverging from the focal point FP' on the left side of the drawing such as the ray L2 shown by the dashed-dot line is incident on the polarized diffractive lens GP1, the polarized diffractive lens GP1 converts the left-handed circularly polarized light (LCP) into right-handed circularly polarized light (RCP) and collimates it. In other words, the polarized diffractive lens GP1 functions like a positive lens with a predetermined focal length for left-handed circularly polarized light (LCP) while reversing the direction of polarization rotation. The polarized diffractive lens GP1 also functions like a negative lens with the same absolute focal length for right-handed circularly polarized light (RCP) while reversing the direction of polarization rotation. In other words, the polarized diffractive lens GP1 is an optical element that has a positive power for left-handed circularly polarized light LCP and a negative power for right-handed circularly polarized light RCP.

[0019] When collimated left-handed circularly polarized light LCP, such as light ray L1 shown by a solid line, enters the polarized diffractive lens GP2 from the left side of the drawing, it converts the left-handed circularly polarized light LCP into right-handed circularly polarized light RCP and diverges it. When collimated right-handed circularly polarized light RCP, such as light ray L1 shown by a solid line, enters the polarized diffractive lens GP2 from the left side of the drawing, it converts the right-handed circularly polarized light RCP into left-handed circularly polarized light LCP and converges the light to focus or condense it at a focal point FP. In other words, the polarized diffractive lens GP2 functions like a positive lens with a predetermined focal length for right-handed circularly polarized light RCP, reversing the direction of polarization rotation. Furthermore, the polarized diffractive lens GP2 functions like a negative lens with the same absolute focal length for left-handed circularly polarized light LCP, reversing the direction of polarization rotation. In other words, the polarized diffractive lens GP2 is an optical element that has negative power for left-handed circularly polarized light LCP and positive power for right-handed circularly polarized light RCP.

[0020] The polarized diffractive lenses GP1 and GP2 have a refractive index anisotropy distribution, which is grasped in a plane by a number of annular zones centered on the optical axis AX, and function as a diffractive lens according to the refractive index anisotropy distribution and the polarization state of the incident light. Specifically, when the polarized diffractive lenses GP1 and GP2 have a refractive index anisotropy distribution in which the orientation of the optical axis rotates (actually repeating in the range of 0 to π) with increasing distance from the optical axis AX in two directions that are perpendicular to the central optical axis AX and perpendicular to each other, a geometric phase is formed in the specific circularly polarized light incident thereon, and the circularly polarized light is diffracted at a diffraction angle that reflects the periodic length of the rotation of the optical axis in each direction, and the polarization state is reversed. As a whole, the polarized diffractive lens causes diffraction corresponding to the power formed by the lens shape for specific circularly polarized light, and reverses the state of circular polarization before and after passing through, for example, from left-handed circularly polarized light to right-handed circularly polarized light.

[0021] Although not shown, the polarized diffractive lenses GP1 and GP2 are each formed by forming a thin liquid crystal-containing material layer on a transparent substrate, and are generally thin and plate-like. The liquid crystal-containing material layer contains a predetermined liquid crystal material. The orientation axes of the liquid crystal molecules are aligned parallel to, for example, the X direction in the region near the optical axis AX to form a desired geometric phase. Furthermore, as the distance from the optical axis AX increases, i.e., depending on the distance or radius from the optical axis AX, the orientation axes of the liquid crystal molecules gradually rotate within the XZ plane perpendicular to the optical axis AX. In other words, the rotation angle of the orientation axes of the liquid crystal molecules increases with the distance from the optical axis AX, and this is repeated periodically. In the liquid crystal compound layer, for example, the orientation axes of the liquid crystal molecules are aligned in a constant manner in the Y direction parallel to the optical axis AX. Note that the direction of increasing the rotation angle of the orientation axes of the liquid crystal molecules is reversed between the polarized diffractive lenses GP1 and GP2. The polarized diffractive lenses GP1 and GP2 are manufactured, for example, by coating a substrate with a liquid crystal-containing material film, which is a mixture of a liquid crystal material and a UV-curable organic material layer, and then two-dimensionally scanning the liquid crystal-containing material film with UV laser light of a specific polarization state to adjust the alignment axis of the liquid crystal molecules and cure the organic material layer. This allows the alignment axis of the liquid crystal molecules in the liquid crystal-containing material layer to be controlled and fixed three-dimensionally, resulting in a liquid crystal compound layer in which the rotation angle of the alignment axis increases with distance from the optical axis AX as described above. Such a polarized diffractive lens GP1 itself is a known technology, such as a polarization-dependent liquid crystal Fresnel lens (see, for example, Kohei Noda, et al., Applied Optics, February 10, 2017, Vol. 56, No. 5: 1302).

[0022] The polarized diffraction lens GP1 and the polarized diffraction lens GP2 do not need to be separate entities; simply rotating the polarized diffraction lens GP1 180° around the Z axis and flipping it over will result in the polarized diffraction lens GP2. In other words, by swapping the polarized diffraction lenses GP1 and GP2, they can function as both positive and negative lenses for the same circularly polarized light. This is because, in the polarized diffraction lenses GP1 and GP2, the alignment axes of the liquid crystal molecules are increased so that they rotate in a specific direction depending on the distance from the optical axis AX, as described above. Therefore, the rotation directions relative to the absolute values ​​of the distances in the ±X directions perpendicular to the optical axis AX, for example, are the same. When each of the polarized diffraction lenses GP1 and GP2 is viewed from the back, the rotation directions of the alignment axes are reversed.

[0023] The focal lengths of the polarized diffractive lenses GP1 and GP2 can be increased or decreased depending on the manufacturing method and liquid crystal material. In the liquid crystal compound layer, for example, when increasing the rotation angle of the alignment axis of the liquid crystal molecules with increasing distance from the optical axis AX, the absolute value of the positive or negative power of the polarized diffractive lenses GP1 and GP2 can be increased by increasing the rate of increase in the rotation angle relative to the distance or radius from the optical axis AX, i.e., by reducing the rotation period of the alignment axis. When passing through the polarized diffractive lenses GP1 and GP2, the loss of circularly polarized light L1 is close to zero, and the polarized diffractive lenses GP1 and GP2 exhibit almost 100% transmittance.

[0024] When linearly polarized light is incident on the polarized diffractive lens GP1, the left-handed circularly polarized light (LCP) and the right-handed circularly polarized light (RCP) behave differently. The left-handed circularly polarized light (LCP) component is converged by the polarized diffractive lens GP1, while the right-handed circularly polarized light (RCP) component is diverged by the polarized diffractive lens GP1, and the rotation direction of each polarization is reversed.

[0025] In this embodiment, left-handed circularly polarized light (LCP), which is the first circularly polarized light C1, and right-handed circularly polarized light (RCP), which is the second circularly polarized light C2, are incident in parallel on polarized diffractive lens 24 (see FIG. 2), which is polarized diffractive lens GP1. The left-handed circularly polarized light (LCP) incident on polarized diffractive lens 24 is converged by polarized diffractive lens 24, and the right-handed circularly polarized light (RCP) incident on polarized diffractive lens 24 is diverged by polarized diffractive lens 24.

[0026] Returning to FIG. 2 , the imaging lens 25 has positive power and forms a virtual image from the image light ML that has passed through the polarized diffractive lens 24. The imaging lens 25 and the polarized diffractive lens 24 function as a composite lens. Here, the polarized diffractive lens 24 has a power whose sign changes depending on whether the incident image light ML is the first circularly polarized light C1 or the second circularly polarized light C2, and the composite lens of the imaging lens 25 and the polarized diffractive lens 24 has two positive focal lengths. In other words, the composite power of the positive power of the imaging lens 25 and the negative power of the polarized diffractive lens 24 is positive. In principle, if the composite power of the positive imaging lens 25 and the positive or negative polarized diffractive lens 24 is positive, a virtual image IM2 can be formed on the near side. However, if the value of this positive and negative composite power becomes smaller, that is, if the positive and negative composite focal length becomes longer, it becomes difficult to move the near-side virtual image IM2 away from the eye, and it also becomes difficult to focus the eye on the near-side virtual image. That is, the absolute value of the power of the polarizing diffractive lens 24 is relatively small compared to the absolute value of the power of the imaging lens 25. The display surface 11d of the display device 11 is disposed between the rear positive-positive composite focal position corresponding to the positive-positive composite power of the positive imaging lens 25 and the positive polarizing diffractive lens 24, and a position closer to the polarizing diffractive lens 24 than the positive-positive composite focal position. The closer the display surface 11d is to the positive-positive composite focal position, the farther away the virtual image IM1 on the far side can be formed.

[0027] The first transmissive mirror 103a partially reflects the image light ML while transmitting a portion of the light. As a result, external light OL passes through the first transmissive mirror 103a, enabling a see-through view of the outside world and allowing a virtual image to be superimposed on an image of the outside world. The reflectance of the first transmissive mirror 103a is set to 10% or more and 50% or less in order to ensure the brightness of the image light ML and to make it easy to observe an image of the outside world through see-through. The first transmissive mirror 103a has a transmissive reflective film 27 formed on a transparent substrate. The transmissive reflective film 27 is formed, for example, of a dielectric multilayer film made of multiple dielectric layers with adjusted thicknesses. The transmissive reflective film 27 may be a single-layer film or a multilayer film made of a metal such as Al or Ag with adjusted thicknesses.

[0028] Although not shown in the drawings, a flat shade having an appearance like a eyeglass lens and having optical transparency can be placed on the external side of the first transmission type mirror 103a.

[0029] The second virtual image display device 100B for the left eye is optically identical to the first virtual image display device 100A for the right eye, or is a left-right inverted version of the first virtual image display device 100A, and a detailed description thereof will be omitted.

[0030] In the first virtual image display device 100A, the optical device excluding the display control device 88 is called the optical unit 100. In the second virtual image display device 100B, the optical device excluding the display control device 88 is called the optical unit 100.

[0031] 5 and 6 are conceptual diagrams illustrating a virtual image formed by the first virtual image display device 100A.

[0032] 5, the first virtual image display device 100A simultaneously displays a first image PP1 corresponding to a virtual image IM1 (see FIG. 2) including a virtual object OB1 to be projected far away, and a second image PP2 corresponding to a virtual image IM2 (see FIG. 2) including a virtual object OB2 to be projected near, in parallel. Specifically, on the display surface 11d of the display device 11 shown in FIG. 3, first elements E1 constituting the first image PP1 and second elements E2 constituting the second image PP2 are allocated in a checkerboard pattern. As a result, of the image light ML emitted from the display surface 11d, the first image light ML1 corresponding to the first image PP1 passes through the first polarizing element PO1 of the polarizing plate 23a to become the first linearly polarized light P1, and then passes through the quarter-wave plate 23b shown in FIG. 2 to become the left-handed circularly polarized light LCP, which is the first circularly polarized light C1. The second video light ML2 corresponding to the second image PP2 passes through the second polarizing element PO2 of the polarizing plate 23a to become the second linearly polarized light P2, and then passes through the quarter-wave plate 23b shown in FIG. 2 to become the right-handed circularly polarized light RCP, which is the second circularly polarized light C2. Note that when the first elements E1 constituting the first image PP1 and the second elements E2 constituting the second image PP2 are allocated in a checkerboard pattern on the display surface 11d, the horizontal width of the images is doubled. In other words, the horizontal widths of the images PP1 and PP2 are doubled.

[0033] 6, first image light ML1 corresponding to one first image PP1 formed in a superimposed state on display 11 is subjected to a converging action through quarter-wave plate 23b and polarized diffractive lens 24 shown in FIG. 2, and forms a virtual image IM1 corresponding to a virtual object OB1 to be projected in the distance through imaging lens 25. Second image light ML2 corresponding to the other second image PP2 formed in a superimposed state on display 11 is subjected to a diverging action through quarter-wave plate 23b and polarized diffractive lens 24 shown in FIG. 2, and forms a virtual image IM2 corresponding to a virtual object OB2 to be projected in the near field through imaging lens 25. In other words, the projected composite image PPC includes a distant virtual object OB1 corresponding to virtual image IM1 and a near virtual object OB2 corresponding to virtual image IM2.

[0034] The virtual images IM1 and IM2 are images that are compressed, for example, in the vertical direction relative to the original images PP1 and PP1, but the original images PP1 and PP1 may be expanded in the vertical direction in advance. Alternatively, the imaging lens 25 may have different projection magnifications in the vertical and horizontal directions.

[0035] In the above explanation, the first element E1 of the first image PP1 and the second element E2 of the second image PP2 are formed in units of pixels PX, but the elements E1 and E2 may also be formed in units of combinations of multiple pixels PX.

[0036] A second type polarized diffractive lens GP2 may be used instead of the first type polarized diffractive lens GP1 as the polarized diffractive lens 24. In this case, the first image PP1 is for near vision, and the second image PP2 is for far vision.

[0037] FIG. 7 illustrates the relative relationship between the virtual images formed by the first virtual image display device 100A for the right eye and the second virtual image display device 100B for the left eye. The display 11 of the first virtual image display device 100A and the display 11 of the second virtual image display device 100B provide a convergence angle corresponding to the virtual image distance of the first image PP1 and the virtual image distance of the second image PP2. In this case, the virtual image distance d1, which is the projection distance to the virtual image IM1 corresponding to the first image PP1, is longer than the virtual image distance d2, which is the projection distance to the virtual image IM2 corresponding to the second image PP2, and the convergence angle α1 of the virtual image IM1 is smaller than the convergence angle α2 of the virtual image IM2. To form such convergence angles α1 and α2, the displays 11 of the virtual image display devices 100A and 100B are horizontally shifted or offset in terms of the display content or arrangement.

[0038] The virtual image display devices 100A, 100B and optical unit 100 of the first embodiment described above include a display 11 that spatially subdivides and emits image light ML corresponding to a first image PP1 and a second image PP2 alternately in space or alternately in time, and a virtual image optical system 20a that is arranged on the light emission side of the display 11 and has a polarized diffractive lens 24 that has positive power for a first circularly polarized light C1 corresponding to linearly polarized light in a first polarization direction D1 and negative power for a second circularly polarized light C2 corresponding to linearly polarized light in a second polarization direction D2, and an imaging lens 25 that has positive power.The virtual image optical system 20a forms virtual images of the first image PP1 and the second image PP2 at different positions by making the first image light ML1 corresponding to the first image PP1 incident on the polarized diffractive lens 24 as the first circularly polarized light C1 and making the second image light ML2 corresponding to the second image PP2 incident on the polarized diffractive lens 24 as the second circularly polarized light C2.

[0039] In the virtual image display device, the transmission mirrors 103a and 103b can superimpose the image light ML on the external light OL transmitted through the transmission mirrors 103a and 103b. In this case, the virtual image optical system 20a causes the first image light ML1 corresponding to the first image PP1 to be incident on the polarized diffractive lens 24 as the first circularly polarized light C1, and causes the second image light ML2 corresponding to the second image PP2 to be incident on the polarized diffractive lens 24 as the second circularly polarized light C2. Therefore, for the image light ML of the first circularly polarized light C1 corresponding to the first image PP1, a virtual image IM1 is formed by the polarized diffractive lens 24 and the imaging lens 25, which have positive power, and for the image light ML of the second circularly polarized light C2 corresponding to the second image PP2, a virtual image IM2 is formed by the polarized diffractive lens 24 and the imaging lens 25, which have negative power. As a result, the virtual images IM1 and IM2 corresponding to the images PP1 and PP2 can be formed in parallel at different positions, i.e., at two focal positions, with the external image as the background. In other words, different virtual images or videos can be viewed at different focal positions substantially simultaneously without moving the virtual image position in the depth direction using a drive mechanism.

[0040] In particular, in this embodiment, the display 11 emits image light ML1, ML2 by spatially alternatingly forming a large number of elements E1 that constitute the first image PP1 and a large number of elements E2 that constitute the second image PP2, and the polarization conversion device 23 of the virtual image optical system 20a has, in order from the display 11, a polarizing plate 23a that is formed by a two-dimensional arrangement of a large number of polarization elements PO1, PO2 that are respectively set in a first polarization direction D1 and a second polarization direction D2 whose polarization directions are perpendicular to each other, corresponding to the large number of elements E1 that constitute the first image PP1 and the large number of elements E2 that constitute the second image, and a 1 / 4 wavelength plate 23b that converts linearly polarized light in the first polarization direction D1 into first circularly polarized light C1 and linearly polarized light in the second polarization direction D2 into second circularly polarized light C2.

[0041] The virtual image display devices 100A and 100B of the present embodiment are capable of displaying virtual images IM1 and IM2 at both near and far angles without using any mechanical mechanism, and can be devices with reduced power consumption.

[0042] Second Embodiment The virtual image display device of the second embodiment will be described below. Note that the virtual image display device of the second embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of parts common to the virtual image display device of the first embodiment will be omitted.

[0043] Fig. 8 is a diagram illustrating the structures of the display 11 and the polarizing plate 23a. In Fig. 8, an area CR1 is a diagram illustrating the display 11, and an area CR2 is a diagram illustrating the polarizing plate 23a.

[0044] The display surface 11d of the display device 11 spatially alternates between a number of elements E1 constituting a first image and a number of elements E2 constituting a second image. The elements E1 and E2 are alternately arranged in a stripe pattern. Here, the first image corresponds to, for example, a virtual image IM1 that is to be projected far away, and the second image corresponds to, for example, a virtual image IM2 that is to be projected near. Each element E1 and E2 corresponds to a pixel PX.

[0045] The polarizing plate 23a has a large number of polarizing elements PO arranged two-dimensionally, and each polarizing element PO includes a first polarizing element PO1 with a first polarization direction D1 and a second polarizing element PO2 with a second polarization direction D2. In the polarizing plate 23a, the first polarizing elements PO1 with the first polarization direction D1 and the polarizing elements PO2 with the second polarization direction D2 are arranged alternately in a stripe pattern.

[0046] In the second embodiment, the first polarizing element PO1 having a first polarization direction D1, which is one of the linear elements provided corresponding to the numerous elements E1 that constitute the first image, can cause the polarizing diffractive lens 24 to function as a lens with positive power, and the polarizing element PO2 having a second polarization direction D2, which is the other linear element provided corresponding to the numerous elements E2 that constitute the second image, can cause the polarizing diffractive lens 24 to function as a lens with negative power. As a result, as in the first embodiment, virtual images IM1 and IM2 corresponding to the images PP1 and PP2 can be formed in parallel at two different focal positions with the external world image as the background (see FIG. 6).

[0047] The first polarizing element PO1 and the polarizing element PO2 that make up the polarizing plate 23a are not limited to a vertical stripe pattern, but may also have a horizontal or diagonal stripe pattern, which is also treated as being arranged in a stripe pattern.

[0048] Third Embodiment The virtual image display device of the third embodiment will be described below. Note that the virtual image display device of the third embodiment is a partial modification of the virtual image display device of the first embodiment, and a description of parts common to the virtual image display device of the first embodiment will be omitted.

[0049] FIG. 9 is a side view illustrating the structures of the display 11, virtual image optical system 20a, and the like incorporated in the first display driver 102a. The virtual image optical system 20a has, in the order of the light ray traveling direction, i.e., from the display 11, a polarization conversion device 123, a polarizing diffraction lens 24, and an imaging lens 25. In the virtual image optical system 20a, the polarization conversion device 123 has, in that order from the display 11, a polarizing plate 123a, a variable wavelength plate 123b, and a quarter-wave plate 123c. The polarizing plate 123a is a polarizing plate whose polarization direction is set to the first polarization direction D1. The variable wavelength plate 123b is, for example, a panel in which a liquid crystal layer is sandwiched between a pair of light-transmitting substrates provided with transparent electrodes, and operates on and off in a time-division manner. In the ON state, the variable wavelength plate 123b converts the first linearly polarized light P1 in the first polarization direction D1 into the second linearly polarized light P2 in the second polarization direction D2 uniformly in the plane, and in the OFF state, passes the first linearly polarized light P1 in the first polarization direction D1 uniformly in the plane as the first linearly polarized light P1. The quarter-wave plate 123c converts the first linearly polarized light P1 in the first polarization direction D1 into the first circularly polarized light C1 and converts the second linearly polarized light P2 in the second polarization direction D2 into the second circularly polarized light C2. The display 11 and the variable wavelength plate 123b of the polarization conversion device 123 operate synchronously.

[0050] The display device 11 alternately forms a first image PP1 and a second image PP2 as shown in Fig. 6 over time, thereby emitting a first image light ML1 and a second image light ML2 corresponding to the first image light ML1 and the second image light ML2. As a result, a virtual image IM1 is formed in the distance by the first image light ML1 that has passed through the polarized diffractive lens 24 with a positive power, and a virtual image IM2 is formed in the near distance by the second image light ML2 that has passed through the polarized diffractive lens 24 with a negative power. The images PP1 and PP2 formed on the display surface 11d of the display device 11 are images that have been reduced in size in the vertical direction compared to those shown in Fig. 6.

[0051] In this embodiment, a first image light ML1 corresponding to a first image PP1 and a second image light ML2 corresponding to a second image PP2 are sequentially emitted from the display 11. The first image light ML1 corresponding to the first image PP1 can be converted into, for example, a first circularly polarized light C1 by the variable wavelength plate 123b and the quarter-wave plate 123c in the ON state, and the second image light ML2 corresponding to the second image PP2 can be converted into the opposite second circularly polarized light C2 by the variable wavelength plate 123b and the quarter-wave plate 123c in the OFF state. As a result, as in the first embodiment, virtual images IM1 and IM2 corresponding to the images PP1 and PP2 can be formed in parallel at two different focal positions with an external world image as a background (see FIG. 6).

[0052] [Fourth embodiment] The virtual image display device of the fourth embodiment will be described below. Note that the virtual image display device of the fourth embodiment is a partial modification of the virtual image display device of the first embodiment or the third embodiment, and a description of parts common to the virtual image display device of the first embodiment will be omitted.

[0053] 10 is a side view illustrating the structure of the display device 11, virtual image optical system 20a, etc., which are incorporated into the first display drive unit 102a. The virtual image optical system 20a has, in order from the display device 11, a polarized diffractive lens 24, a polarization conversion device 223, and an imaging lens 25.

[0054] The display 11 has a polarizing element 11p. The display 11 temporally alternately forms a first image light ML1 corresponding to a first image PP1 and a second image light ML2 corresponding to a second image PP2, and emits the image lights ML1 and ML2 as image light ML, which is a first linearly polarized light P1 in a first polarization direction D1. The polarization conversion device 223 is disposed on the external side of the polarizing diffraction lens 24, and has, in this order from the polarizing diffraction lens 24, a quarter-wave plate 223a, a variable wavelength plate 223b, and a polarizing plate 223c. The display 11 and the polarization conversion device 223 operate synchronously. The quarter-wave plate 223a converts the first image light ML1, which has been converted from the first circularly polarized light C1 to the second circularly polarized light C2 after passing through the polarizing diffraction lens 24, into the first linearly polarized light P1 in the first polarization direction D1, and converts the second image light ML2, which has been converted from the second circularly polarized light C2 to the first circularly polarized light C1 after passing through the polarizing diffraction lens 24, into the second linearly polarized light P2 in the second polarization direction D2. The variable wavelength plate 223b operates on and off in a time-division manner, and converts the second linearly polarized light P2 in the second polarization direction D2 into the first linearly polarized light P1 in the first polarization direction D1 when in the on state. When in the off state, the variable wavelength plate 223b transmits the first image light ML1 as the first linearly polarized light P1 in the first polarization direction D1. In other words, when the variable wavelength plate 223b is in the off state, the first image light ML1 displayed on the display 11 ultimately becomes the first linearly polarized light P1 in the first polarization direction D1, passes through the polarizing plate 223c, and enters the imaging lens 25 from the polarization conversion device 223. When the variable wavelength plate 223b is in the on state, the second image light ML2 displayed on the display 11 finally becomes the first linearly polarized light P1 in the first polarization direction D1 and enters the imaging lens 25 from the polarization conversion device 223.

[0055] In the above, the functions of the quarter-wave plate 223a and the polarizing plate 223c are not limited to those shown in the drawings. Furthermore, the polarizing element 11p of the display 11 is also not limited to the polarization direction shown in the drawings, and can switch the polarization transmission direction. For example, by adjusting the angle of the quarter-wave plate 223a around the optical axis AX, the first image light ML1 emitted from the quarter-wave plate 223a can be converted into the second linearly polarized light P2, and the second image light ML2 emitted from the quarter-wave plate 223a can be converted into the first linearly polarized light P1. In this case, the polarization transmission direction of the polarizing plate 223c is switched to allow the second linearly polarized light P2 in the second polarization direction D2 to pass through.

[0056] [Variations and Others] The present invention has been described above in accordance with the embodiments, but the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0057] The quarter-wave plate 23b can be made of a liquid crystal material. The quarter-wave plate 23b and the polarized diffractive lens 24 are not limited to those that two-dimensionally scan a liquid crystal-containing material film with UV laser light in a predetermined polarization state to adjust the alignment axes of the liquid crystal molecules while curing the organic material layer, but can also be produced by the method for producing a liquid crystal optical element described in, for example, JP-A-2008-501147.

[0058] In the above, it has been described that the HMD 200 comprises a first virtual image display device 100A and a second virtual image display device 100B, but the HMD 200 may also be configured to support a single first virtual image display device 100A or second display device 100B in front of the eyes by a support device 106.

[0059] In the above, the virtual image display devices 100A and 100B are not limited to the HMD 200, but may be incorporated as an in-vehicle device.

[0060] The transmissive mirrors 103a and 103b may be omitted or may not be transparent. In this case, the virtual image optical system 20a becomes an optical system that is directly observed, and the virtual image display devices 100A and 100B become closed types instead of see-through types.

[0061] In a specific embodiment, a virtual image display device includes a display device that spatially subdivides and emits image light corresponding to a first image and a second image alternately in space or alternately in time, and a virtual image optical system that is arranged on the light emission side of the display device and has a polarized diffractive lens that has positive power for a first circularly polarized light and negative power for a second circularly polarized light, and an imaging lens that has positive power.The virtual image optical system forms virtual images of the first image and the second image at different positions by making the image light corresponding to the first image incident on the polarized diffractive lens as the first circularly polarized light and making the image light corresponding to the second image incident on the polarized diffractive lens as the second circularly polarized light.

[0062] In the virtual image display device, a transmission mirror can be used to superimpose image light on external light passing through the transmission mirror. In this case, a virtual image is formed by a polarized diffractive lens and an imaging lens having positive power for the first circularly polarized image light corresponding to the first image, and a virtual image is formed by a polarized diffractive lens and an imaging lens having negative power for the second circularly polarized image light corresponding to the second image. Consequently, virtual images corresponding to the respective images can be formed in parallel at two different focal positions with the external image as a background. In other words, different virtual images or images can be displayed substantially simultaneously at different focal positions without moving the virtual image positions in the depth direction using a drive mechanism.

[0063] In a specific aspect of the virtual image display device, the display emits image light by spatially alternating a large number of elements constituting a first image and a large number of elements constituting a second image, and the virtual image optical system includes, in order from the display, a polarization conversion device, a polarizing diffractive lens, and an imaging lens. The polarization conversion device includes, in order from the display, a polarizing plate formed by two-dimensionally arranging a large number of polarizing elements set in a first polarization direction and a second polarization direction that are orthogonal to each other, corresponding to the large number of elements constituting the first image and the large number of elements constituting the second image, and a quarter-wave plate that converts linearly polarized light in the first polarization direction into first circularly polarized light and linearly polarized light in the second polarization direction into second circularly polarized light. In this case, the first image and the second image are spatially subdivided in the display, and a large number of polarizing elements can be arranged in the polarizing plate to match the large number of elements constituting the first image and the second image, and the image light corresponding to the first image can be the first circularly polarized light and the image light corresponding to the second image can be the second circularly polarized light.

[0064] In a specific embodiment of the virtual image display device, polarizing elements of a first polarization direction and polarizing elements of a second polarization direction are alternately arranged in a checkerboard pattern on the polarizing plate. In this case, the polarizing elements of the first polarization direction, which are rectangular elements provided corresponding to each element of the first image, can cause the polarizing diffractive lens to function as a lens with positive power, and the polarizing elements of the second polarization direction, which are rectangular elements provided corresponding to each element of the second image, can cause the polarizing diffractive lens to function as a lens with negative power.

[0065] In a specific embodiment of the virtual image display device, polarizing elements of a first polarization direction and polarizing elements of a second polarization direction are alternately arranged in a stripe pattern on the polarizing plate. In this case, the polarizing elements of the first polarization direction, which are linear elements provided corresponding to each element of the first image, can cause the polarizing diffractive lens to function as a lens with positive power, and the polarizing elements of the second polarization direction, which are linear elements provided corresponding to each element of the second image, can cause the polarizing diffractive lens to function as a lens with negative power.

[0066] In a specific aspect of the virtual image display device, the display emits image light by alternately forming a first image and a second image over time, and the virtual image optical system includes, in order from the display, a polarization conversion device, a polarizing diffractive lens, and an imaging lens, and the polarization conversion device includes, in order from the display, a polarizer whose polarization direction is set to a first polarization direction, a variable wavelength plate that operates on and off in a time-division manner to convert linearly polarized light in the first polarization direction into linearly polarized light in a second polarization direction, and a quarter-wave plate. In this case, image light corresponding to the first image and image light corresponding to the second image are sequentially emitted from the display, and the variable wavelength plate and quarter-wave plate in the on state can convert the image light corresponding to the first image into, for example, a first circularly polarized light, and the variable wavelength plate and quarter-wave plate in the off state can convert the image light corresponding to the second image into the opposite, second circularly polarized light.

[0067] In a specific aspect of the virtual image display device, the display unit alternately forms a first image and a second image over time to output image light as linearly polarized light in a first polarization direction. The virtual image optical system includes, in order from the display unit, a polarizing diffractive lens, a polarization conversion device, and an imaging lens. The polarization conversion device includes, in order from the polarizing diffractive lens, a quarter-wave plate that converts second circularly polarized light that has passed through the polarizing diffractive lens into linearly polarized light in the first polarization direction, a variable wavelength plate that operates on and off in a time-division manner and converts linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction in the on state, and a polarizer whose polarization direction is set to the first polarization direction. In this case, image light corresponding to the first image and image light corresponding to the second image are sequentially output from the display unit. The first circularly polarized component of the image light is subjected to a converging action by the polarizing diffractive lens, and the second circularly polarized component of the image light is subjected to a diverging action. The convergent image light then passes through the quarter-wave plate and the variable wavelength plate in the off state before passing through the polarizer. The divergent image light passes through the quarter wave plate and the variable wave plate in the ON state, and then passes through the polarizer.

[0068] In a specific embodiment of the virtual image display device, the power obtained by combining the negative power of the polarizing diffractive lens and the positive power of the imaging lens is a positive value, in which case a closer image is formed at a position corresponding to the combined power, and a farther image is formed at a position corresponding to the combined power of the positive power of the polarizing diffractive lens and the positive power of the imaging lens.

[0069] In a specific embodiment of the virtual image display device, the polarizing diffractive lens converts left-handed circularly polarized light, which is a first circularly polarized light, of the image light from the display device into right-handed circularly polarized light, which is a second circularly polarized light.

[0070] In a specific embodiment of the virtual image display device, the polarizing diffractive lens converts right-handed circularly polarized light, which is a first circularly polarized light, of the image light from the display device into left-handed circularly polarized light, which is a second circularly polarized light.

[0071] In a specific embodiment, the virtual image display device further includes a transmission mirror that reflects the image light from the imaging lens toward the pupil position.

[0072] A specific aspect of the virtual image display device includes a first virtual image display device that is any one of the above-described virtual image display devices and forms a first image for the right eye, and a second virtual image display device that is any one of the above-described virtual image display devices and forms a second image for the left eye, wherein the display of the first virtual image display device and the display of the second virtual image display device provide a convergence angle that corresponds to the virtual image distance of the first image and the virtual image distance of the second image. In this case, the occurrence of convergence accommodation conflict can be suppressed, and the user can be prevented from feeling fatigue.

[0073] In a specific embodiment, the optical unit includes a display that spatially subdivides and emits image light corresponding to a first image and a second image alternately in space or alternately in time, a virtual image optical system that is arranged on the light emission side of the display and has a polarized diffractive lens that has positive power for the first circularly polarized light and negative power for the second circularly polarized light, and an imaging lens that has positive power, and the virtual image optical system forms virtual images of the first image and the second image at different positions by making the image light corresponding to the first image incident on the polarized diffractive lens as the first circularly polarized light and making the image light corresponding to the two images incident on the polarized diffractive lens as the second circularly polarized light. [Explanation of symbols]

[0074] 11...display device, 11d...display surface, 20a...virtual image optical system, 20b...imaging optical system, 23...polarization conversion device, 23a...polarizing plate, 23b...quarter wave plate, 24...polarized diffraction lens, 25...imaging lens, 27...transmissive reflective film, 88...display control device, 90...user terminal, 100...optical unit, 100A, 100B...virtual image display device, 100C...temple, 102...drive device, 102a, 102b...display drive unit, 103a, 103b...transmissive mirror, 106...support device, 123...polarization conversion device, 123a...polarizing plate, 123b...variable wave plate, 123c...1 / 4 wavelength plate, 200...head-mounted display device, AX...optical axis, E1...first element of first image, E2...second element of second image, EY...eye, FP...focus, FP'...focus, GP1, GP2...polarized diffractive lens, IM1, IM2...virtual image, L1, L2...light ray, LCP...left circularly polarized light, RCP...right circularly polarized light, ML...image light, ML1, ML2...image light, OB1, OB2...virtual object, OL...external light, PO...polarizing element, PO1, PO2...polarizing elements, PP1...first image, PP1...second image, PPC...synthetic image, PX...pixel, PXs...subpixel, US...wearer, α1, α2...convergence angle

Claims

1. a display device that spatially subdivides and alternately emits image light corresponding to the first image and the second image, or alternately emits image light corresponding to the first image and the second image; a virtual image optical system arranged on the light exit side of the display, the virtual image optical system including a polarizing diffractive lens having positive power for a first circularly polarized light and negative power for a second circularly polarized light, and an imaging lens having positive power; Equipped with The virtual image optical system causes image light corresponding to the first image to be incident on the polarized diffractive lens as the first circularly polarized light, and causes image light corresponding to the second image to be incident on the polarized diffractive lens as the second circularly polarized light, thereby forming virtual images of the first image and the second image at different positions. Virtual image display device.

2. the display emits the image light by spatially alternatingly forming a large number of elements constituting the first image and a large number of elements constituting the second image; the virtual image optical system includes, in order from the display, a polarization conversion device, the polarization diffraction lens, and the imaging lens; The polarization conversion device includes, in order from the display, a polarizing plate formed by two-dimensionally arranging a large number of polarizing elements, each set in a first polarization direction and a second polarization direction that are orthogonal to each other, corresponding to a large number of elements that form the first image and a large number of elements that form the second image, and a quarter-wave plate that converts linearly polarized light in the first polarization direction into the first circularly polarized light and linearly polarized light in the second polarization direction into the second circularly polarized light. The virtual image display device according to claim 1 .

3. In the polarizing plate, the polarizing elements of the first polarization direction and the polarizing elements of the second polarization direction are alternately arranged in a checkerboard pattern. The virtual image display device according to claim 2 .

4. In the polarizing plate, the polarizing elements of the first polarization direction and the polarizing elements of the second polarization direction are alternately arranged in a stripe pattern. The virtual image display device according to claim 2 .

5. the display emits the image light by forming the first image and the second image alternately in time; the virtual image optical system includes, in order from the display, a polarization conversion device, the polarization diffraction lens, and the imaging lens; The polarization conversion device includes, in this order from the display, a polarizer whose polarization direction is set to a first polarization direction, a variable wavelength plate that operates on and off in a time division manner and that converts linearly polarized light in the first polarization direction into linearly polarized light in a second polarization direction that intersects with the first polarization direction when in an on state, and a quarter wavelength plate. The virtual image display device according to claim 1 .

6. the display device emits the image light as linearly polarized light in a first polarization direction by forming the first image and the second image alternately in time; the virtual image optical system includes, in order from the display device, the polarizing diffractive lens, a polarization conversion device, and the imaging lens; The polarization conversion device includes, in this order from the polarizing diffraction lens, a quarter-wave plate that converts the second circularly polarized light that has passed through the polarizing diffraction lens back into linearly polarized light, a variable wavelength plate that operates on and off in a time-division manner and, when on, converts the linearly polarized light in the first polarization direction into linearly polarized light in a second polarization direction that intersects the first polarization direction, and a polarizer. The virtual image display device according to claim 1 .

7. a power obtained by combining the negative power of the polarized diffractive lens and the positive power of the imaging lens is a positive value; The virtual image display device according to claim 1 .

8. the polarized diffractive lens converts the first circularly polarized light, which is left-handed circularly polarized light, of the image light from the display device into the second circularly polarized light, which is right-handed circularly polarized light. The virtual image display device according to claim 1 .

9. the polarized diffractive lens converts the first circularly polarized light, which is right-handed circularly polarized light, of the image light from the display device into the second circularly polarized light, which is left-handed circularly polarized light. The virtual image display device according to claim 1 .

10. a transmission mirror that reflects the image light from the imaging lens toward a pupil position, The virtual image display device according to claim 1 .

11. The virtual image display device according to any one of claims 1 to 10, comprising: a first virtual image display device that forms a first image for a right eye; The virtual image display device according to any one of claims 1 to 10, comprising: a second virtual image display device that forms a second image for the left eye; Equipped with the display of the first virtual image display device and the display of the second virtual image display device provide a convergence angle corresponding to a virtual image distance of the first image and a virtual image distance of the second image; Virtual image display device.

12. a display device that spatially subdivides and alternately emits image light corresponding to the first image and the second image, or alternately emits image light corresponding to the first image and the second image; a virtual image optical system arranged on the light exit side of the display, the virtual image optical system including a polarizing diffractive lens having positive power for a first circularly polarized light and negative power for a second circularly polarized light, and an imaging lens having positive power; The virtual image optical system causes image light corresponding to the first image to be incident on the polarized diffractive lens as the first circularly polarized light, and causes image light corresponding to the second image to be incident on the polarized diffractive lens as the second circularly polarized light, thereby forming virtual images of the first image and the second image at different positions. Optical unit.

Images