Head-mounted display device, optical unit, and method of manufacturing optical unit

Abstract

To protect a combiner and hard coating from impact.SOLUTION: A head-mounted display device 200 includes: a display element 11a that forms an image; a projection optical system 12a projecting the image formed in the display element; a combiner 103a having a first inside surface that reflects the image projected from the projection optical system and a first outside surface that faces the first inside surface, and configured to allow external light OL from the first outside surface to transmit to the first inside surface; a hard coating 73 which is formed on the first outside surface and the first inside surface of the combiner to protect the first outside surface and the first inside surface of the combiner; and a cushioning member 70 arranged along an outer peripheral end of the combiner to mitigate the impact to the outer peripheral end of the combiner, thereby protecting the hard coating from damage.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a head-mounted display device and optical unit that enable viewing of a virtual image, and a method for manufacturing the optical unit. [Background technology]

[0002] A known display device configuration includes a projection lens that passes image light from an image element, a prism mirror that causes the image light emitted from the projection lens to enter through a light entrance surface, reflect off an internal reflection surface, and emit from a light exit surface, and a see-through mirror that reflects the image light emitted from the prism mirror toward the pupil position (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-86170 Summary of the Invention [Problem to be solved by the invention]

[0004] In the display device of the background art described above, the see-through mirror as the preocular optical component is thin and exposed to the outside world, so it is desirable to provide a hard coating to prevent damage to its surface and to easily remove dirt from the surface. However, if the preocular optical component is relatively thin or made of resin, when a relatively large force is applied, such as when the display device is dropped, the preocular optical component may be instantaneously deformed, resulting in damage such as cracks in the hard coating. In particular, in the case of a relatively thin preocular optical component such as a combiner, its edge is easily subjected to impact when dropped, and the hard coating is likely to be damaged. [Means for solving the problem]

[0005] A head-mounted display device and optical unit in one aspect of the present invention comprises a display element that forms an image, a projection optical system that projects the image formed on the display element, a combiner that has a first inner surface that reflects the image projected from the projection optical system and a first outer surface opposite the first inner surface, and that transmits external light from the first outer surface to the first inner surface, a hard coat that is formed on the first outer surface and the first inner surface of the combiner and protects the first outer surface and the first inner surface of the combiner, and a buffer member that is provided along the outer peripheral edge of the combiner and that absorbs impacts on the outer peripheral edge of the combiner and protects the hard coat from damage.

[0006] A method for manufacturing an optical unit in one aspect of the present invention includes: generating a combiner having a first outer surface and a first inner surface opposite the first outer surface; forming a hard coat on the surface of the combiner; applying a cushioning material along the outer peripheral edge of the combiner; hardening the material to form the cushioning material; and assembling a display element that forms an image, a projection optical system that projects the image formed on the display element, and a combiner that reflects the image projected from the projection optical system at the first inner surface and transmits external light from the first outer surface to the first inner surface to manufacture the optical unit, wherein the cushioning material absorbs impacts on the outer peripheral edge of the combiner and protects the hard coat from damage. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an external perspective view illustrating a state in which a head-mounted display device according to an embodiment is worn; [Figure 2] FIG. 2 is a side cross-sectional view illustrating the internal structure of one of the display devices. [Figure 3] FIG. 2 is a side cross-sectional view specifically illustrating the optical structure of the display unit. [Figure 4] FIG. 10 is a front view illustrating the positional relationship between a combiner and a buffer member. [Figure 5] FIG. 4 is a cross-sectional view illustrating the positional relationship between a combiner and a buffer member. [Figure 6]1 is a flowchart illustrating a method for manufacturing an optical unit according to an embodiment. [Figure 7] 10A-10C are cross-sectional views illustrating a process for forming a combiner. [Figure 8] 10A-10C are cross-sectional views illustrating a process for forming a combiner. [Figure 9] 10A-10C are cross-sectional views illustrating a process for forming a combiner. [Figure 10] 10A-10C are cross-sectional views illustrating a process for forming a combiner. [Figure 11] 10A-10C are cross-sectional views illustrating a process for forming a combiner. [Figure 12] FIG. 4 is a cross-sectional view illustrating the positional relationship between a combiner and a buffer member. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Embodiment] Hereinafter, an embodiment of a head-mounted display device according to the present invention will be described with reference to FIGS.

[0009] 1 is a diagram illustrating a wearing state of a head-mounted display device (hereinafter also referred to as a head-mounted display or HMD) 200, in which the HMD 200 allows an observer or wearer US wearing the device 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 or image display device 100 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 or front direction for the wearer US. The ±Y directions are parallel to the vertical axis or vertical direction.

[0010] The HMD 200 includes a first display device 100A for the right eye, a second display device 100B for the left eye, a pair of temple-shaped support devices 100C that support the display devices 100A and 100B, and a user terminal 90, which is an information terminal. The first display device 100A functions independently as an HMD and is composed of a first display driver 102a disposed at the top and a first combiner 103a shaped like a pair of glasses that covers the eyes. The second display device 100B similarly functions independently as an HMD and is composed of a second display driver 102b disposed at the top and a second combiner 103b shaped like a pair of glasses that covers the eyes. The support device 100C is a mounting member worn on the head of the wearer US and supports the upper ends of the pair of combiners 103a and 103b via the display drivers 102a and 102b, which appear integrated in appearance. The first display device 100A and the second display device 100B are optically identical or are mirror-inverted versions of each other, and a detailed description of the second display device 100B will be omitted.

[0011] FIG. 2 is a side cross-sectional view illustrating the internal structure of the first display device 100A. The first display device 100A includes a first display element 11a, a first display unit 20a, and a first circuit member 80a. The first display element 11a is an image light generating device, also referred to as an imaging element. The first display unit 20a is an imaging optical system that forms a virtual image and includes a projection lens 21, a prism mirror 22, and a see-through mirror 23 integrated together. The projection lens 21 and the prism mirror 22 of the first display unit 20a function as a first projection optical system 12a onto which the image light ML from the first display element 11a is incident. The see-through mirror 23 functions as a partial transmission mirror 123 that partially reflects the image light ML emitted from the first projection optical system 12a toward the pupil position PP or the eye EY. The first projection optical system 12a projects the image formed on the first display element 11a. The first display unit 20a has a first projection optical system 12a and a first combiner 103a integrated together. The projection lens 21 constituting the first projection optical system 12a corresponds to the first optical member 2a arranged on the light-exiting side of the first display element 11a, and the prism mirror 22 corresponds to the second optical member 2b arranged on the light-exiting side of the first optical member 2a, which is the projection lens 21. The first display element 11a, the projection lens 21, and the prism mirror 22 correspond to part of the first display drive unit 102a shown in FIG. 1, and the see-through mirror 23 is arranged on the light-exiting side of the second optical member 2b and corresponds to the first combiner 103a shown in FIG. 1. The projection lens 21 and the prism mirror 22 constituting the first projection optical system 12a are fixed in a container-shaped barrel 41 while being positioned relative to the first display element 11a. The barrel 41 is a case CA that houses the optical elements that make up the first projection optical system 12a in a positioned state.

[0012] The barrel 41, which supports the optical members 2a and 2b that make up the first projection optical system 12a, is supported by the first frame 52a and is disposed below the first frame 52a. The first frame 52a is covered by a cover 171, which also entirely covers the barrel 41. The first frame 52a is formed of a metal material. The barrel 41 and the cover 171 are formed of a light-blocking resin material, and one surface of the prism mirror 22 is exposed at the exit 41o of the barrel 41. The upper barrel cover 41u of the barrel 41 abuts against the first frame 52a so as to fit therewith, and the barrel 41 is fixed in a suspended state to the first frame 52a. As a result, the first display unit 20a is fixed in a suspended state to the first frame 52a via the barrel 41. The first frame 52a has a recess RE on its upper side for disposing the first circuit member 80a.

[0013] In the first display device 100A, the first display element 11a is a self-luminous image light generating device. The first display element 11a emits image light ML to the first projection optical system 12a. The barrel 41 houses and supports the first display element 11a together with the optical elements constituting the first projection optical system 12a. The first display element 11a is, for example, an organic electroluminescence (EL) display, and forms color still or moving images on a two-dimensional display surface 11d. The first display element 11a performs a display operation driven by a first circuit member 80a and a display control device 88 including the first circuit member 80a. The first display element 11a is not limited to an organic EL display, and 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 first display element 11a is not limited to a self-luminous image light generating device, and may be configured with an LCD or other light modulation element, and an image may be formed by illuminating the light modulation element with a light source such as a backlight. Instead of an LCD, the first display element 11a may be an LCOS (Liquid Crystal on Silicon, LCoS is a registered trademark), a digital micromirror device, etc. Note that the first display device 100A excluding the display control device 88 or the first circuit member 80a is also referred to as the image display device 100.

[0014] FIG. 3 is a side cross-sectional view specifically illustrating the optical structure of the first display unit 20a. The first display unit 20a includes two reflecting surfaces, and the optical path is bent by the see-through mirror 23 and the prism mirror 22. The first display unit 20a is an off-axis optical system OS. The projection lens 21, prism mirror 22, and see-through mirror 23 are arranged asymmetrically about an axis. In this first display unit 20a, the optical axis AX is bent within an off-axis plane parallel to the YZ plane, which is the reference plane, and the optical elements 21, 22, and 23 are arranged along this off-axis plane (i.e., the reference plane). Specifically, on the off-axis plane parallel to the YZ plane and corresponding to the paper surface, an optical path portion P1 from the projection lens 21 to the reflecting surface 22b, an optical path portion P2 from the reflecting surface 22b to the see-through mirror 23, and an optical path portion P3 from the see-through mirror 23 to the pupil position PP are arranged to be bent in two stages in a Z-shape. Correspondingly, an optical axis portion AX1 from the projection lens 21 to the reflecting surface 22b, an optical axis portion AX2 from the reflecting surface 22b to the see-through mirror 23, and an optical axis portion AX3 from the see-through mirror 23 to the pupil position PP are arranged so as to be folded back in two stages in a Z shape. In the see-through mirror 23, the normal to the central location where the optical axis AX intersects forms an angle θ of approximately 40 to 50° with respect to the Z direction. In this first display unit 20a, the optical elements 21, 22, and 23 constituting the first display device 100A are arranged with their height positions changed in the vertical direction, which prevents the width of the first display device 100A from increasing. Furthermore, by folding the optical path due to reflection by prism mirror 22 or the like, optical path portions P1-P3 or optical axis portions AX1-AX3 are arranged to be folded back in two stages in a Z shape, and because optical path portions P1, P3 or optical axis portions AX1, AX3 are relatively close to horizontal, first display unit 20a can be made smaller in the up-down and front-back directions. Also, because the tilt angle θ at the center of see-through mirror 23 is 40-50°, if the tilt of optical path portion P3 corresponding to the line of sight is constant, the tilt of optical path portion P2 with respect to the Z axis is 70-90°, making it easy to reduce the thickness of image display device 100 in the Z direction.

[0015] In the first display unit 20a, the optical path portion P1 from the projection lens 21 to the reflecting surface 22b extends slightly obliquely upward toward the rear relative to the viewpoint or in a direction nearly parallel to the Z direction. The optical path portion P2 from the reflecting surface 22b to the see-through mirror 23 extends obliquely downward toward the front. When the horizontal plane (XZ plane) is used as the reference, the inclination of the optical path portion P2 is greater than the inclination of the optical path portion P1. The optical path portion P3 from the see-through mirror 23 to the pupil position PP extends slightly obliquely upward toward the rear or in a direction nearly parallel to the Z direction. In the illustrated example, the portion of the optical axis AX corresponding to the optical path portion P3 is angled approximately -10° toward the +Z direction, with downward being negative. In other words, the partially transmitting mirror 123 reflects the image light ML so that the optical axis AX or the optical path portion P3 is angled upward by a predetermined angle, that is, approximately 10° upward. As a result, the exit optical axis EX, which is an extension of the optical axis portion AX3 corresponding to the optical path portion P3, extends at a downward tilt of approximately 10° with respect to the central axis HX, which is parallel to the forward +Z direction. This is because the human line of sight is stable with eyes slightly downcast, tilted approximately 10° downward from the horizontal. Note that the central axis HX, which extends horizontally with respect to the pupil position PP, is designed to be aligned with the assumption that the wearer US wearing the first display device 100A is in an upright, relaxed position, facing forward, and gazing horizontally or at the horizon.

[0016] Of the first display unit 20a, the projection lens 21 includes a first lens 21o, a second lens 21p, and a third lens 21q. The projection lens 21 receives image light ML emitted from the first display element 11a and makes it incident on a prism mirror 22. The projection lens 21 condenses the image light ML emitted from the first display element 11a into a nearly parallel beam. The entrance surface 21a and exit surface 21b of the first lens 21o, the entrance surface 21c and exit surface 21d of the second lens 21p, and the entrance surface 21e and exit surface 21f of the third lens 21q, which constitute the projection lens 21, are free-form surfaces or aspherical surfaces. The optical surfaces 21a, 21b, 21c, 21d, 21e, and 21f are asymmetric about the optical axis AX in the vertical direction, which is parallel to the YZ plane and intersects with the optical axis AX, and are symmetric about the optical axis AX in the horizontal direction or X direction. The first lens 21o, the second lens 21p, and the third lens 21q are formed of, for example, resin, but can also be made of glass. An anti-reflection film can be formed on the optical surfaces of the first lens 21o, the second lens 21p, and the third lens 21q that make up the projection lens 21.

[0017] The prism mirror 22 is an optical member with a refractive and reflective function that combines the functions of a mirror and a lens, and refracts and reflects the image light ML from the projection lens 21. The prism mirror 22 has an incident surface 22a arranged on the light-exiting side of the first optical member 2a, a reflecting surface 22b that bends the optical axis AX, and an exit surface 22c that faces the reflecting surface 22b and is arranged symmetrically to the incident surface 22a. The prism mirror 22 outputs the image light ML, which is incident from the front where the projection lens 21 is arranged, by bending the image light ML in a direction that is inclined downward with respect to a direction that reverses the incident direction (the direction of the light source as seen from the prism mirror 22). The incident surface 22a, the reflecting surface 22b, and the exit surface 22c, which are optical surfaces that constitute the prism mirror 22, are asymmetric about the optical axis AX in the vertical direction that is parallel to the YZ plane and intersects the optical axis AX, and are symmetric about the optical axis AX in the horizontal direction or X direction. The optical surfaces of the prism mirror 22, i.e., the entrance surface 22a, the reflection surface 22b, and the exit surface 22c, are, for example, free-form surfaces. The entrance surface 22a, the reflection surface 22b, and the exit surface 22c are not limited to free-form surfaces, but can also be aspherical. The prism mirror 22 is formed, for example, from resin, but can also be made of glass. The reflection surface 22b is not limited to one that reflects the image light ML by total reflection, but can also be a reflection surface made of a metal film or a dielectric multilayer film. In this case, a reflection film made of a single layer or multilayer film made of a metal such as Al or Ag is formed on the reflection surface 22b by vapor deposition or the like, or a sheet-like reflection film made of metal is attached. Although detailed illustration is omitted, an anti-reflection film can be formed on the entrance surface 22a and the exit surface 22c.

[0018] The exit surface 22c of the prism mirror 22 is concave overall, and is concave on an off-axis plane parallel to the YZ plane and through which the optical axis portions AX1 to AX3 pass, i.e., on the paper surface. It is also concave on a cross section CS (see FIG. 2) perpendicular to the YZ plane and passing through the center of the exit surface 22c. Because the exit surface 22c of the prism mirror 22 is exposed at the exit port 41o of the barrel 41, making it concave makes it easier to avoid contact with external objects, thereby reducing the occurrence of damage. The exit surface 22c of the prism mirror 22 is located near the relatively small intermediate image IM, where the cross section of the beam of the image light ML is narrowed, and therefore its area can be made relatively small. Making the area of the exit surface 22c of the prism mirror 22 relatively small also reduces damage to the exit surface 22c.

[0019] The see-through mirror 23, i.e., the first combiner 103a, is a curved, plate-like reflective optical member that functions as a concave surface mirror, and reflects the image light ML from the prism mirror 22 while partially transmitting the external light OL. The see-through mirror 23 reflects the image light ML from the prism mirror 22 toward the pupil position PP. The see-through mirror 23 has a reflective surface 23c and an outer surface 23o.

[0020] The see-through mirror 23 partially reflects the image light ML. The see-through mirror 23 is a concave mirror that covers the pupil position PP where the eye EY or pupil is located and has a concave shape toward the pupil position PP and a convex shape toward the outside. The pupil position PP or its opening PPa is called the eyepoint or eyebox. The pupil position PP or the opening PPa corresponds to the exit pupil EP on the exit side of the first display unit 20a. The see-through mirror 23 is a collimator that converges, to the pupil position PP, the chief rays of the image light ML that are emitted from each point on the display surface 11d and that spread after forming an image near the exit side of the prism mirror 22 of the first projection optical system 12a. As a concave mirror, the see-through mirror 23 enables the intermediate image IM formed on the first display element 11a, which is an image light generating device, and re-imaged by the first projection optical system 12a to be viewed in an enlarged form. More specifically, the see-through mirror 23 functions similarly to a field lens, collimating image light ML from each point on the intermediate image IM formed downstream of the exit surface 22c of the prism mirror 22 and directing it toward the pupil position PP so that the image light ML is collected as a whole. Since the see-through mirror 23 is positioned between the intermediate image IM and the pupil position PP, it must have an area larger than the effective area EA, which corresponds to the angle of view. Here, the angle of view is the sum of the vertical and horizontal viewing angles based on the optical axis AX extending in the direction directly in front of the eye EY, and is set to approximately 40 to 50° in a specific example. The outer area of the see-through mirror 23, extending beyond the effective area EA, can have any surface shape because it does not directly affect image formation. However, from the perspective of ensuring an appearance resembling that of a spectacle lens, it is desirable for the curvature of the outer edge of the effective area EA to be the same as that of the surface shape, or for the curvature to vary continuously from that edge.

[0021] The see-through mirror 23 is a semi-transparent mirror plate having a structure in which a transmissive reflective film 23a is formed on the rear surface of a plate-shaped body 23b. The reflective surface 23c of the see-through mirror 23 is asymmetrical about the optical axis AX in the vertical direction parallel to the YZ plane and intersecting the optical axis AX, and is symmetrical about the optical axis AX in the horizontal direction or X direction. The reflective surface 23c of the see-through mirror 23 is, for example, a free-form surface. The reflective surface 23c is not limited to a free-form surface, but can also be an aspherical surface. The reflective surface 23c must have an area equal to or greater than the effective area EA. If the reflective surface 23c is formed in an outer area wider than the effective area EA, there is less difference in appearance between an external image from behind the effective area EA and an external image from behind the above-mentioned outer area.

[0022] The reflecting surface 23c of the see-through mirror 23 transmits a portion of the image light ML when reflecting it. This allows the external light OL to pass through the see-through mirror 23, enabling a see-through view of the external world and allowing a virtual image to be superimposed on the external world image. In this case, if the plate-shaped body 23b is thin (several millimeters or less), the change in magnification of the external world image can be minimized. The reflectance of the reflecting surface 23c for the image light ML and the external light OL is set to 10% or more and 50% or less within the expected range of incident angles of the image light ML (corresponding to the effective area EA) in order to ensure the brightness of the image light ML and facilitate the observation of the external world image through see-through. The plate-shaped body 23b, which is the base material of the see-through mirror 23, is formed of, for example, resin, but can also be made of glass. The plate-shaped body 23b is formed of the same material as the support plate 61 that supports it from the periphery and has the same thickness as the support plate 61. The transmissive reflective film 23a is formed of, for example, a dielectric multilayer film consisting of multiple dielectric layers with adjusted film thicknesses. The transmissive reflective film 23a may be a single-layer film or a multi-layer film made of a metal such as Al or Ag, with the film thickness adjusted. The transmissive reflective film 23a can be formed by laminating layers using vapor deposition, for example, or by attaching a sheet-like reflective film. An anti-reflection film is formed on the outer surface 23o of the plate-shaped body 23b.

[0023] Regarding the optical path, image light ML from the first display element 11a enters the projection lens 21 and exits from the projection lens 21 in a substantially collimated state. After passing through the projection lens 21, the image light ML enters the prism mirror 22, passes through the entrance surface 22a while being refracted, is reflected by the reflecting surface 22b with a high reflectance close to 100%, and is refracted again by the exit surface 22c. The image light ML from the prism mirror 22 temporarily forms an intermediate image IM, then enters the see-through mirror 23 and is reflected by the reflecting surface 23c with a reflectance of approximately 50% or less. The image light ML reflected by the see-through mirror 23 enters the pupil position PP, where the eye EY or pupil of the wearer US is located. External light OL that passes through the see-through mirror 23 and the support plate 61 around it also enters the pupil position PP. In other words, the wearer US wearing the first display device 100A can observe a virtual image formed by the image light ML superimposed on an external image.

[0024] The configuration and positional relationship of the combiner 103a and the buffer member 70 will be described with reference to Figures 4 and 5. Note that Figure 5 shows the dimensions, shapes, and directions of each component element roughly.

[0025] A portion of the combiner 103a other than the outer peripheral edge, including the effective area EA onto which the image light ML from the projection optical system 12a is projected, is referred to as a central portion 71. A sloped structure 72 is formed at the outer peripheral edge of the combiner 103a. While FIG. 5 omits some features to simply illustrate the configuration of the combiner 103a, in reality, the surface of the sloped structure 72 may be sloped relative to the outer surface 71o and / or the inner surface 71i of the combiner 103a. The sloped structure 72 may include a stepped structure whose thickness discontinuously decreases from the connection portion with the combiner 103a toward the outer edge. In the example of FIG. 5 , an inner recess 72i recessed outward (in the +Z direction) is formed in the sloped structure 72 on the inner surface 71i of the combiner 103a in the -Z direction (the concave surface facing the eye EY of the wearer US in FIGS. 2 and 3 ). The combiner 103a has an outer surface 71o (the convex surface onto which the external light OL is incident in FIGS. 2 and 3) on which an outer recess 72o recessed inward (in the −Z direction) is formed in the inclined structure 72. The thickness T2 of the inclined structure 72 is thinner than the thickness T1 of the central portion 71.

[0026] The surface of the combiner 103a is covered with a scratch-resistant hard coat 73. The hard coat 73 protects the surface of the combiner 103a. The hard coat 73 may cover the entire inner surface 71i and outer surface 71o of the central portion 71 and the sloped structure 72 of the combiner 103a. The hard coat 73 may also cover the lower (-Y direction) surfaces of the inner recesses 72i and outer recesses 72o.

[0027] The outer surface 71o of the combiner 103a is further covered with an antireflection layer 74 on top of the hard coat 73. The antireflection layer 74 suppresses reflection of external light OL incident on the outer surface 71o of the combiner 103a. The antireflection layer 74 may include a first antireflection layer 74a and a second antireflection layer 74b that respectively cover the central portion 71 and the sloped structure 72 of the combiner 103a. The antireflection layer 74 does not have to cover the lower (-Y direction) surface of the outer recess 72o.

[0028] The inner surface 71i of the combiner 103a is further covered with a half mirror layer 75 on top of the hard coat 73. The half mirror layer 75 reflects a portion of the incident light and transmits another portion. The half mirror layer 75 in FIG. 5 may have the same configuration as the transmissive reflective film 23a in FIGS. 2 and 3. The half mirror layer 75 may include a first half mirror layer 75a and a second half mirror layer 75b that respectively cover the central portion 71 and the sloped structure 72 of the combiner 103a. The half mirror layer 75 does not have to cover the lower (-Y direction) surface of the inner recess 72i.

[0029] The combiner 103a configured as described above functions as the see-through mirror 23 and the partial transmission mirror 123 described with reference to FIGS. 2 and 3 due to the laminated structure of the hard coat 73, the anti-reflection layer 74, and the half mirror layer 75.

[0030] The buffer member 70 extends along at least a portion of the outer peripheral edge of the combiner 103a that is lower (in the -Y direction) than the upper (+Y direction) end of the effective area EA. The buffer member 70 is supported by the inclined structure 72 and is arranged so as to cover the inclined structure 72 from the outside. The buffer member 70 is preferably arranged so as not to cover the effective area EA.

[0031] The buffer member 70 has elasticity and protects the combiner 103a and the hard coat 73 by absorbing impacts on the outer peripheral edge of the combiner 103a that may occur when the head-mounted display device 200 is dropped, for example. As an example, the elastic modulus of the buffer member 70 may be approximately 10 MPa or less. To prevent the buffer member 70 from easily coming off the combiner 103a, a portion of the surface of the buffer member 70 that faces the inclined structure 72 of the combiner 103a may have a shape complementary to the inclined structure 72 and may be in close contact with the surface of the inclined structure 72. The buffer member 70 may be optically transparent so as to minimize discomfort in the field of view of the wearer US who observes the image light ML and the external light OL using the combiner 103a.

[0032] As an example, the thickness T1 of the central portion 71 of the combiner 103a is 1 mm to 2 mm, the thickness T2 of the sloped structure 72 is 0.5 mm to 1.6 mm, the thickness of the hard coat 73 is on the order of several micrometers, the thickness of the antireflection layer 74 is on the order of several hundred nanometers, the thickness of the half mirror layer 75 is on the order of several hundred nanometers, and the thickness T0 of the buffer member 70 is on the order of several millimeters. Here, when the thickness T1 is 1 mm, about half of the thickness T1 may be left as the thickness T2, and when the thickness T1 is 2 mm, a step of about 0.2 mm may be provided on each side of the central portion 71. Furthermore, the width by which the buffer member 70 covers each of the first antireflection layer 74a and the first half mirror layer 75a is on the order of 1 mm.

[0033] A method for manufacturing the optical unit 300 according to one embodiment will be described with reference to the flowchart of Fig. 6 and the cross-sectional views of Fig. 7 to Fig. 11. When the flowchart of Fig. 6 starts, step S1 is executed.

[0034] In step S1 of FIG. 6, the combiner 103a is molded. As an example, the combiner 103a is molded by injection molding using a mold such as a die before the hard coat 73 is formed on the surface. As shown in FIG. 7, the molded combiner 103a has a central portion 71 and a sloped structure 72. An ejector pin may be used to push the injection-molded combiner 103a out of the mold. When the ejector pin pushes the combiner 103a out of the mold, a pressure mark may remain on the molded product where the ejector pin hits, which may locally degrade the optical performance at the mark. The ejector pin may be positioned to hit the surface of the sloped structure 72, which will later be covered with the buffer member 70, to reduce the possibility of scratches and / or marks on the central portion 71, including the effective area EA.

[0035] After step S1 in FIG. 6, step S2 is performed. In step S2 in FIG. 6, a hard coat 73 is formed on the surface of the combiner 103a. As an example, the hard coat 73 may be formed by a dipping process. In this case, the combiner 103a as a substrate is immersed in a treatment tank filled with a coating liquid, which is the material for the hard coat 73, and then pulled out and dried. As a result, the hard coat 73 is formed on the surface of the combiner 103a, as shown in FIG. 8.

[0036] Step S3 is performed after step S2 in FIG. 6 . In step S3 in FIG. 6 , an antireflection layer 74 is formed on the outer surface 71o of the combiner 103a. As an example, the antireflection layer 74 may be formed by vacuum deposition. In this case, the material of the antireflection layer 74 is evaporated and deposited on the convex surface serving as the outer surface 71o of the combiner 103a disposed inside a vacuum chamber or the like. This process may be performed multiple times. At this time, the material of the antireflection layer 74 is less likely to deposit on the lower (−Y direction) surface of the inclined structure 72 than on the outer surface 71o because the surface is closer to perpendicular to the deposition direction. Therefore, the antireflection layer 74 formed on the outer surface 71o of the combiner 103a may be substantially divided into the first antireflection layer 74a and the second antireflection layer 74b shown in FIG. 5 . As a result, as shown in FIG. 9, an antireflection layer 74 (a first antireflection layer 74a and a second antireflection layer 74b) is formed on the hard coat 73 of the combiner 103a.

[0037] After step S3 in FIG. 6, step S4 is performed. In step S4 in FIG. 6, a half mirror layer 75 is formed on the inner surface 71i of the combiner 103a. As an example, the half mirror layer 75 may be formed by vacuum deposition, similar to the anti-reflection layer 74. However, the half mirror layer 75 is formed on the concave surface serving as the inner surface 71i of the combiner 103a. At this time, similar to the anti-reflection layer 74, the half mirror layer 75 may be divided into a first half mirror layer 75a and a second half mirror layer 75b shown in FIG. 5. As a result, as shown in FIG. 10, the half mirror layer 75 (first half mirror layer 75a and second half mirror layer 75b) is formed on the hard coat 73 of the combiner 103a. Note that the order of performing steps S3 and S4 in FIG. 6 may be reversed.

[0038] Step S5 is performed after step S4 in FIG. 6. In step S5 in FIG. 6, the material of the buffer member 70 is applied along the outer peripheral edge of the combiner 103a. As an example, the material of the buffer member 70 is an adhesive that remains elastic even after hardening. When applying the material of the buffer member 70, a supply port for supplying the material is moved along an inclined structure 72 formed on the outer peripheral edge of the combiner 103a, so that the material can be accurately positioned on the outer peripheral edge of the combiner 103a.

[0039] Step S6 is performed after step S5 in Fig. 6. In step S6 in Fig. 6, the buffer member 70 is hardened. As a result, the buffer member 70 is formed to cover the slope structure 72, as shown in Fig. 11.

[0040] Step S7 is executed after step S6 in Fig. 6. In step S7 in Fig. 6, the combiner 103a, the display element 11a, and the projection optical system 12a are assembled. As a result, the optical unit 300 shown in Fig. 2 and the like is obtained.

[0041] As described above, according to the head-mounted display device 200, the optical unit 300, and the manufacturing method of the optical unit 300 according to one embodiment, by providing a hard coat 73 that protects the surface of the combiner 103a and a buffer member 70 that protects the outer peripheral edge of the combiner 103a and the hard coat 73, it is possible to effectively prevent damage to the head-mounted display device 200 and the optical unit 300 due to impact when dropped, while suppressing any discomfort in the field of vision of the wearer US.

[0042] [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.

[0043] In the above embodiment, a configuration in which the inclined structure 72 includes a step structure has been described. As a variation of this configuration, the inclined structure 72 may include a tapered structure, as shown in FIG. 12. In the example of FIG. 12, the thickness of the inclined structure 72 continuously decreases from a thickness T3 at the connection portion with the combiner 103a to a thickness T2 at the outer edge portion of the inclined structure 72. Furthermore, as shown in the example of FIG. 12, the inclined structure 72 may simultaneously include a tapered structure in which the thickness continuously decreases and a step structure in which the thickness discontinuously decreases.

[0044] In the above embodiment, a configuration in which the buffer member 70 is light-transmitting has been described. As a variation of this configuration, the buffer member 70 may be light-absorbing. In this case, reflection and scattering of the external light OL that passes through the combiner 103a and the image light ML that is reflected by the combiner 103a can be suppressed, thereby reducing the discomfort that may occur in the field of vision of the wearer US due to the presence of the buffer member 70.

[0045] In the above embodiment, a configuration has been described in which the material of the cushioning member 70 is an adhesive that remains elastic even after hardening. As a variation of this configuration, the material of the cushioning member 70 may be a resin that remains elastic even after hardening. As an example, the material may be an acrylic or silicone resin that hardens at room temperature and remains elastic even after hardening.

[0046] In the above, the HMD 200 is described as comprising a first display device 100A and a second display device 100B, but the HMD 200 or the image display device 100 may also be configured such that a single first display device 100A or second display device 100B is supported in front of the eyes by a support device 100C.

[0047] The optical members 2a and 2b of the first projection optical system 12a are not limited to those shown in the figure, and for example, the number of optical elements constituting the first optical member 2a and the shape of the optical surface can be changed as appropriate depending on the purpose of use of the HMD 200, etc.

[0048] In the above description, it is assumed that the HMD 200 is worn on the head, but the image display device 100 can also be used as a handheld display that is not worn on the head but is peered at like binoculars. In other words, in the present invention, the head-mounted display also includes a handheld display.

[0049] In a specific embodiment, the head-mounted display device comprises: a display element that forms an image; a projection optical system that projects the image formed on the display element; a combiner that has a first inner surface that reflects the image projected from the projection optical system and a first outer surface opposite the first inner surface, and that transmits external light from the first outer surface to the first inner surface; a hard coat that is formed on the first outer surface and the first inner surface of the combiner and protects the first outer surface and the first inner surface of the combiner; and a cushioning member that is provided along the outer peripheral edge of the combiner and protects the hard coat from damage by absorbing impacts to the outer peripheral edge of the combiner.

[0050] In the above-mentioned head-mounted display device, by providing a hard coat that protects the surface of the combiner and a cushioning member that protects the outer edges of the combiner and the hard coat, it is possible to suppress any discomfort in the wearer's field of vision while effectively suppressing damage to the head-mounted display device due to impacts such as when it is dropped.

[0051] In a specific embodiment of the head-mounted display device, the combiner further has a central portion other than the outer peripheral end portion, including a first outer surface and a first inner surface, and an inclined structure provided along the outer peripheral end portion and having a second thickness thinner than the first thickness of the central portion of the combiner, and the buffer member is supported by the inclined structure and covers the inclined structure.

[0052] In a specific embodiment of the head-mounted display device, the inclined structure includes a tapered structure whose thickness continuously decreases from the connection portion with the combiner toward the outer edge portion.

[0053] In a specific embodiment of the head-mounted display device, the inclined structure includes a step structure in which the thickness discontinuously decreases from the connection portion with the combiner toward the outer edge portion.

[0054] In a specific embodiment of a head-mounted display device, the scratch-resistant hard coat includes a first outer hard coat formed on a first outer surface of the combiner and a second outer hard coat formed on a second outer surface of the inclined structure, and further includes a first anti-reflection layer formed on the surface of the first outer hard coat to suppress reflection of incident light, and a second anti-reflection layer formed on the surface of the second outer hard coat, and the buffer member further covers at least a portion of the first anti-reflection layer and the entire second anti-reflection layer.

[0055] In a specific embodiment of a head-mounted display device, the hard coat includes a first inner hard coat formed on a first inner surface of the combiner and a second inner hard coat formed on a second inner surface of the inclined structure, and further includes a first half-mirror layer formed on the surface of the first inner hard coat and reflecting a portion of the incident light and transmitting another portion of the incident light, and a second half-mirror layer formed on the surface of the second inner hard coat, and the buffer member further covers at least a portion of the first half-mirror layer and the entire second half-mirror layer.

[0056] In a specific embodiment of the head-mounted display device, the buffer member includes a resin that is applied to the outer peripheral edge along the inclined structure and then cured.

[0057] In a specific embodiment of the head-mounted display device, the elastic modulus of the buffer member after hardening is 10 MPa or less.

[0058] In a specific embodiment of the head-mounted display device, the buffer member is optically transparent.

[0059] In a specific embodiment of the head-mounted display device, the buffer member has light-absorbing properties.

[0060] In a specific embodiment, the optical unit includes: a display element that forms an image; a projection optical system that projects the image formed on the display element; a combiner that has a first outer surface and a first inner surface opposite the first outer surface, and that reflects the image projected from the projection optical system at the first inner surface and transmits external light from the first outer surface to the first inner surface; a hard coat that is formed on the first outer surface and the first inner surface of the combiner and protects the first outer surface and the first inner surface of the combiner; and a buffer member that is provided along the outer peripheral edge of the combiner and protects the hard coat from damage by absorbing impacts to the outer peripheral edge of the combiner.

[0061] In the above optical unit, by providing a hard coat that protects the surface of the combiner and a cushioning material that protects the outer edges of the combiner and the hard coat, it is possible to effectively prevent damage to the head-mounted display device due to impacts such as when it is dropped while suppressing any discomfort in the wearer's field of vision.

[0062] In a specific embodiment, a method for manufacturing an optical unit includes: generating a combiner having a first outer surface and a first inner surface opposite the first outer surface; forming a hard coat on the surface of the combiner; applying a buffer material along the outer peripheral edge of the combiner; hardening the material to form the buffer; and assembling a display element that forms an image, a projection optical system that projects the image formed on the display element, and a combiner that reflects the image projected from the projection optical system at the first inner surface and transmits external light from the first outer surface to the first inner surface to manufacture the optical unit, wherein the buffer material protects the hard coat from damage by absorbing impacts on the outer peripheral edge of the combiner.

[0063] In the optical unit manufactured by the above method, a hard coat that protects the surface of the combiner and a cushioning material that protects the outer edges of the combiner and the hard coat are provided, thereby suppressing any discomfort in the wearer's field of vision and effectively preventing damage to the head-mounted display device due to impacts such as when it is dropped. [Explanation of symbols]

[0064] 2a...first optical member, 2b...second optical member, 11a...display element, 11d...display surface, 12a...projection optical system, 20a...display unit, 21...projection lens, 21, 22, 23...optical element, 21o, 21p, 21q...lens, 22...prism mirror, 22a...incident surface, 22b...reflecting surface, 22c...exit surface, 23...see-through mirror, 23a...transmissive reflective film, 41...barrel, 41o...exit port, 41u...barrel cover, 52a...first frame, 61...support plate, 70...buffer member, 71...center portion, 71i...inner surface, 71o...outer surface, 72...inclined structure, 72i...inner recess, 72o...outer recess, 73...hard coat, 74...anti-reflection layer, 74a...first anti-reflection layer, 74b...second anti-reflection layer, 7 5...half mirror layer, 75a...first half mirror layer, 75b...second half mirror layer, 80a...circuit member, 88...display control device, 90...user terminal, 100...image display device, 100A, 100B...display device, 100C...support device, 102a, 102b...display drive unit, 103a, 103b...combiner, 123...partially transmitting mirror, 171...cover, 200...head-mounted display device, 300...optical unit, AX...optical axis, AX1-AX3...optical axis portion, CA...case, EA...effective area, EP...exit pupil, EY...eye, IM...intermediate image, ML...image light, OL...external light, OS...off-axis optical system, P1-P3...optical path portion, PP...pupil position, RE...recess, T1, T2, T3...thickness, US...wearer

Claims

1. a display element for forming an image; a projection optical system that projects the image formed on the display element; a combiner having a first inner surface that reflects the image projected from the projection optical system and a first outer surface facing the first inner surface, and transmitting external light from the first outer surface to the first inner surface; a hard coat formed on the first outer surface and the first inner surface of the combiner, the hard coat protecting the first outer surface and the first inner surface of the combiner; a buffer member provided along the outer peripheral edge of the combiner to absorb impacts on the outer peripheral edge of the combiner and protect the hard coat from damage; Equipped with Head-mounted display device.

2. The combiner comprises: a central portion other than the outer peripheral end portion, the central portion including the first outer surface and the first inner surface; a ramp structure along the outer periphery having a second thickness less than the first thickness of the central portion of the combiner; and The buffer member is supported by the inclined structure and covers the inclined structure. The head-mounted display device according to claim 1 .

3. The inclined structure includes a tapered structure whose thickness continuously decreases from a connection portion with the combiner toward an outer edge portion. The head-mounted display device according to claim 2 .

4. The inclined structure includes a step structure in which the thickness discontinuously decreases from the connection portion with the combiner toward the outer edge portion. The head-mounted display device according to claim 2 .

5. The hard coat is a first outer hard coat formed on the first outer surface of the combiner; a second outer hard coat formed on a second outer surface of the gradient structure; Including, a first anti-reflection layer formed on the surface of the first outer hard coat to suppress reflection of incident light; a second anti-reflection layer formed on the surface of the second outer hard coat; Furthermore, the buffer member further covers at least a portion of the first antireflection layer and the entire second antireflection layer; The head-mounted display device according to any one of claims 2 to 4.

6. The hard coat is a first inner hard coat formed on the first inner surface of the combiner; a second inner hard coat formed on the second inner surface of the gradient structure; Including, a first half mirror layer formed on a surface of the first inner hard coat, the first half mirror layer reflecting a part of incident light and transmitting another part of the incident light; a second half mirror layer formed on the surface of the second inner hard coat; Furthermore, the buffer member further covers at least a portion of the first half mirror layer and the entire second half mirror layer; The head-mounted display device according to claim 2 or 5.

7. the buffer member includes a resin that is applied to the outer peripheral end along the inclined structure and then cured; The head-mounted display device according to any one of claims 2 to 4.

8. The elastic modulus of the buffer member after hardening is 10 MPa or less. The head-mounted display device according to claim 7 .

9. The buffer member has optical transparency. The head-mounted display device according to claim 1 .

10. The buffer member has light absorption properties. The head-mounted display device according to claim 1 .

11. The combiner is molded using a mold; The outer peripheral end portion has a mark where an ejector pin was pressed to remove the combiner from the mold, in a portion covered by the buffer member. The head-mounted display device according to claim 1 .

12. a display element for forming an image; a projection optical system that projects the image formed on the display element; a combiner having a first inner surface that reflects the image projected from the projection optical system and a first outer surface facing the first inner surface, and transmitting external light from the first outer surface to the first inner surface; a hard coat formed on the first outer surface and the first inner surface of the combiner, the hard coat protecting the first outer surface and the first inner surface of the combiner; a buffer member provided along the outer peripheral edge of the combiner to absorb impacts on the outer peripheral edge of the combiner and protect the hard coat from damage; Equipped with Optical unit.

13. creating a combiner having a first outer surface and a first inner surface opposite the first outer surface; forming a hard coat on the surface of the combiner; applying a shock absorber material along an outer peripheral edge of the combiner; curing the material to form the cushioning member; manufacturing an optical unit by assembling a display element that forms an image, a projection optical system that projects the image formed on the display element, and the combiner that reflects the image projected from the projection optical system on the first inner surface and transmits external light from the first outer surface to the first inner surface; Including, The buffer member absorbs impacts on the outer peripheral edge of the combiner and protects the hard coat from damage. A manufacturing method for an optical unit.

Images