Patent Application
20220003989
The present disclosure relates to a head-mounted virtual image display apparatus and a virtual image display method.
Head-mounted virtual image display apparatuses are requested to achieve both high resolution and wide viewing angles to increase a sense of immersion. To concurrently offer comfortable wearability, it is also necessary to reduce the size and the weight of an apparatus that is worn by a viewer.
It is difficult in general that a small and light-weighted head-mounted virtual image display apparatus achieves both high resolution and a wide viewing angle while suppressing the manufacturing cost.
It is desirable to provide a head-mounted virtual image display apparatus and a virtual image display method each of which makes it possible to provide a viewer with comfortable wearability and a sense of immersion.
A virtual image display apparatus according to an embodiment of the present disclosure includes: a plurality of image forming elements; and a plurality of eyepiece optical systems. The plurality of image forming elements includes a first image forming element and a second image forming element. The first image forming element outputs a first image to a front region in a visual field of a viewer. The second image forming element outputs a second image to a peripheral region in the visual field of the viewer. The second image is different from the first image. The plurality of image forming elements outputs a plurality of images to cause an image region of at least a portion of each of the plurality of images to overlap with the first image. The plurality of images includes the first and second images. The plurality of eyepiece optical systems is provided in association with the plurality of respective image forming elements. The plurality of eyepiece optical systems forms one virtual image as a whole from the plurality of images.
A virtual image display method according to an embodiment of the present disclosure includes: a step of displaying a plurality of images by a plurality of respective image forming elements; a step of outputting the plurality of images via a plurality of eyepiece optical systems corresponding to the plurality of respective image forming elements; and a step of correcting images that are displayed on the plurality of image forming elements on the basis of at least one of optical characteristics of the plurality of eyepiece optical systems, characteristics of a pencil of light rays, or light emission characteristics of the plurality of image forming elements to cause images outputted via the plurality of eyepiece optical systems to form the one virtual image. The characteristics of the pencil of light rays are geometrically determined from a pupil position and a pupil diameter of the viewer and a position and an inclination angle of a boundary surface in the eyepiece optical systems.
In the virtual image display apparatus according to the embodiment of the present disclosure, the plurality of image forming elements outputs the plurality of images to cause at least a portion of each of the plurality of images to have an image region overlapping with the first image. The plurality of images includes the first and second images. In addition, the plurality of eyepiece optical systems that is provided in association with the plurality of respective image forming elements forms one virtual image as a whole from the plurality of images.
In the virtual image display method according to the embodiment of the present disclosure, the images that are displayed on the plurality of image forming elements are corrected on the basis of at least one of the optical characteristics of the plurality of eyepiece optical systems, the characteristics of the pencil of light rays, or the light emission characteristics of the plurality of image forming elements to cause the images that are outputted via the plurality of eyepiece optical systems to form the one virtual image. The characteristics of the pencil of light rays are geometrically determined from the pupil position and the pupil diameter of the viewer and the position and the inclination angle of the boundary surface in the eyepiece optical systems.
The following describes embodiments of the present disclosure in detail with reference to the drawings. It is to be noted that description is given in the following order.
Method according to Embodiment of the Present Disclosure
In a case where an image forming element having a limited number of pixels is viewed by using an eyepiece optical system, the pixel count per angle is determined in general in accordance with a viewing angle. The resolution and the viewing angle thus have a trade-off relationship. Although there is also means for increasing an image forming element in area to increase the pixel count while keeping pixel density, this is not favorable because this increases the whole of the apparatus in size. A variety of techniques are reported (see PTLs 1 to 3 and NPTL 1) to resolve the trade-off relationship described above and achieve a reduction in apparatus size and weight. The variety of techniques include viewing one virtual image obtained by joining images with a plurality of image forming elements and a plurality of eyepiece optical systems. In addition, there is also a technique of increasing a viewing angle by using a single image forming element and a single eyepiece optical system (see PTL 4).
For example, a technique is known that uses two image forming elements for each of eyes to increase the viewing angle while suppressing an increase in virtual image display apparatus size and weight (see, for example, PTL 1).
Meanwhile, a technique is also known that achieves a compact optical design by using an eyepiece optical system divided into a plurality of small lenses including a free-form surface to view one image forming element for each of eyes to increase the viewing angle while keeping high resolution (see, for example, PTL 2).
In addition, a technique is also known that achieves a compact optical design by using two eyepiece optical systems each including a free-form surface to view two small and high-definition image forming elements for each of eyes to increase the viewing angle while keeping high resolution (see, for example, NPTL 1).
In addition, a technique is also known that increases only the resolution near the gazing point of a viewer by using a half mirror for the region of a portion of a virtual image having a wide visual field region outputted from a first image forming element and superimposing a virtual image having high resolution outputted from a second image forming element to obtain a virtual image display apparatus having high resolution and a wide viewing angle (see, for example, PTL 3).
The technique described in PTL 1 uses two image forming elements for each of eyes. A vertical field angle of at least about 100° is, however, necessary for an eyepiece optical system disposed right in front of a viewer to increase a sense of immersion. Further, a horizontal field angle of 90° (45° on the nose side) or more is also necessary. An image forming element of several inches or more is therefore necessary to achieve this viewing angle by using one eyepiece optical system including a Fresnel lens or the like. In recent years, liquid crystal displays and OLED (organic EL) displays each having high pixel density have been under development as image forming devices of several inches. Whichever display is used, a virtual image to be viewed has an angular resolution of 5 to 6 minutes of arc. This falls short of an angular resolution of 1 to 2 minutes of arc. Human eyes have an angular resolution of 1 to 2 minutes of arc. It is thus difficult to obtain a sufficient sense of immersion.
In the technique described in PTL 2, an eyepiece optical system divided into small lenses allows for an optical design corresponding to the characteristics of human eyes. Each of eyes, however, has only one image forming element. This requests an image forming device of several inches to achieve a wide viewing angle. As described above, PTL 2 also has a problem with insufficient resolution as with PTL 1. Further, a joint position of a virtual image is disposed to overlap with the front region in the visual field of a viewer. This increases the risk that the border between images is visually recognized or the risk that the physical border between adjacent small lenses is visually recognized.
The technique described in NPTL 1 includes two small and high-definition image forming elements for each of eyes. The size of each of the image forming elements is one inch. This is competitive price. Each eye, however, has a horizontal field angle of 92° and a vertical field angle of 75°. This makes it difficult to obtain a sufficient sense of immersion. To achieve a viewing angle of at least 100° or more, four or more image forming elements are necessary for each of eyes in consideration of symmetry. This causes higher manufacturing cost.
The technique described in PTL 3 uses a half mirror and superimposes a virtual image having high resolution. The technique described in PTL 3 thus has a configuration of great optical path length. As a viewing angle is increased, the volume of an eyepiece optical system extremely increases. In addition, the field angle region is narrow in which a high resolution output is obtained. This requests a display region to be dynamically driven in real time while detecting the line-of-sight direction of a viewer. This causes a large-scale sliding mechanism to be disposed in front of eyes and makes it difficult to achieve a reduction in virtual image display apparatus size and weight.
In addition, PTL 4 discloses a technique for a head-mounted display apparatus including an image forming element having a flat middle portion and a curved peripheral portion. The head-mounted display apparatus has a configuration in which the pixel size of the peripheral portion of the screen is greater than that of the middle portion of the screen. The technique described in PTL 4 uses a single image forming element and a single image forming element for each of eyes to increase the viewing angle. In the technique described in PTL 4, the middle portion and the peripheral portion of a single image forming element have to be different in pixel size and planar shape. This requests a special manufacturing method. Accordingly, the technique described in PTL 4 is disadvantageous in manufacturing cost.
As described above, it is difficult in general that a small and light-weighted head-mounted virtual image display apparatus achieves both high resolution and a wide viewing angle while suppressing the manufacturing cost.
Accordingly, it is desired to develop a relatively small and light-weighted head-mounted virtual image display apparatus and a virtual image display method each of which makes it possible to achieve high resolution and a wide viewing angle while suppressing the manufacturing cost and provide a viewer with comfortable wearability and a sense of immersion.
A head-mounted virtual image display apparatus according to an embodiment of the present disclosure includes a plurality of image forming elements that outputs a plurality of images and a plurality of eyepiece optical systems that is provided in association with the plurality of respective image forming elements and forms one virtual image as a whole from the plurality of images. The plurality of image forming elements includes a first high-definition and small image forming element that displays an image which is outputted to the front region in the visual field of a viewer and second to N-th (N represents an integer of 3 or more) image forming elements that are each lower than the first image forming element in resolution and each display an image which is outputted to a peripheral region in the visual field of the viewer. The plurality of eyepiece optical systems includes a first eyepiece optical system that is provided in association with the first image forming element and second to N-th eyepiece optical systems (other eyepiece optical systems) that are provided in association with the second to N-th image forming elements. The head-mounted virtual image display apparatus according to the embodiment is characterized in that a first image displayed by the first image forming element is not a subset of any of second to N-th images displayed by the second to N-th image forming elements. The head-mounted virtual image display apparatus according to the embodiment is configured to have a viewer to view the first to N-th images as joined into one virtual image via the first to N-th eyepiece optical systems that are respectively appropriate for the first to N-th images. The first to N-th images are displayed by the first to N-th image forming elements.
In such a configuration, the first high-definition image forming element is used for a stable gazing field to output a virtual image having high resolution. In the stable gazing field, a human exhibits an excellent visual function. The second to N-th image forming elements each of which is relatively low in manufacturing cost are used for a peripheral visual field to output virtual images that are lower than that of the first image forming element in resolution. In the peripheral visual field, a human exhibits low information discrimination capability. This makes it possible to prevent the virtual image display apparatus from having unnecessarily too high performance and optimize the balance between resolution and manufacturing cost.
In addition, the number of second to N-th image forming elements and the number of second to N-th eyepiece optical systems and the disposition of second to N-th image forming elements and the disposition of second to N-th eyepiece optical systems are adjusted in accordance with a viewing angle requested from the virtual image display apparatus. This makes it possible to relatively easily achieve a wide viewing angle.
In addition, the first image forming element disposed right in front of a viewer is small and the field angle of a virtual image is also limited to the stable gazing field. This allows the corresponding first eyepiece optical system to have a relatively compact optical design. Further, to make an optical design for a wide viewing angle, it is easier to secure optical performance by using a plurality of divided eyepiece optical systems rather than a single eyepiece optical system and it is also possible to reduce the respective eyepiece optical systems in height. As a result, it is thus possible to achieve a reduction in virtual image display apparatus size and weight as a whole.
In the head-mounted virtual image display apparatus according to the embodiment, for example, the first eyepiece optical system outputs a virtual image having 60° or more and 120° or less as the horizontal field angle and 45° or more and 100° or less as the vertical field angle. As a result, a virtual image outputted from the first eyepiece optical system and virtual images outputted from the second to N-th eyepiece optical systems are joined together in a region that transitions to the peripheral visual field from the stable gazing field. This makes it possible to avoid the risk that the border between images is visually recognized. Further, such a configuration also alleviates the risk that the physical border between the first eyepiece optical system and the second to N-th eyepiece optical systems which is adjacent to the first eyepiece optical system is visually recognized.
For example, the first image forming element of the head-mounted virtual image display apparatus according to the embodiment has a resolution of 2000 ppi or more and the second to N-th image forming elements each have a resolution of less than 2000 ppi. This makes it possible to output a virtual image to at least the stable gazing field with an angular resolution of 2 minutes of arc or less. In the stable gazing field, a human exhibits an excellent visual function. As a result, it is possible to view a virtual image that is equal to or more than an angular resolution of 1 to 2 minutes of arc. Human eyes have an angular resolution of 1 to 2 minutes of arc. This allows a viewer to have a sufficient sense of resolution.
More desirably, in the first to N-th eyepiece optical systems, the position of the boundary surface between two given adjacent eyepiece optical systems is designed to join two given adjacent virtual images that are outputted from the respective eyepiece optical systems to cause two given adjacent virtual images to constantly have overlapping regions even in the presence of eyeball rotation accompanying the line-of-sight movement of a viewer in the stable gazing field (see a first embodiment,
More desirably, in the first to N-th eyepiece optical systems, the inclination angle of the boundary surface between two given adjacent eyepiece optical systems is designed to reduce (suppress) the vignetting of a pencil of light rays passing near the boundary surface even in the presence of eyeball rotation accompanying the line-of-sight movement of a viewer in the stable gazing field (see the first embodiment,
The first to N-th eyepiece optical systems may be designed to form a smoothly curved virtual image surface as a whole to cover a viewer's field of vision. Alternatively, while each of the eyepiece optical systems forms a flat virtual image surface, eyepiece optical systems disposed closer to the periphery may be designed to form more inclined virtual image surfaces, thereby forming a discretely curved virtual image surface as a whole to cover a viewer's field of vision (see the first embodiment and
At least one eyepiece optical system of the first to N-th eyepiece optical systems may include at least one Fresnel lens (see the first to fourth embodiments,
The second to N-th eyepiece optical systems may be each designed as an eyepiece optical system that has a different optical scheme from that of the first eyepiece optical system (see the second to fourth embodiments and
For example, the second to N-th eyepiece optical systems may be each designed as an eyepiece optical system of an optical scheme in which a free-form surface prism or a free-form surface mirror is included. Such a configuration makes it possible to select the optimum optical scheme in accordance with optical performance necessary for the peripheral visual field. In addition, a flexible optical design is possible such as securing sufficient space in front of eyes (space from the face of a viewer to the optical surface that is the closest to the eyes) to allow a viewer to wear the virtual image display apparatus with glasses on and satisfying a requirement caused by a housing design.
The first to N-th eyepiece optical systems may be designed to cause at least the surface positioned the closest to the eye side of a viewer to be shared as the same lens surface between the first to N-th respective eyepiece optical systems (see the fifth embodiment and
The head-mounted virtual image display apparatus according to the embodiment of the present disclosure may further include a sliding mechanism that makes it possible to control the distance (virtual image distance) from an observer to a virtual image surface by each of a plurality of eyepiece optical systems (see the first embodiment and
For example, the first to N-th eyepiece optical systems are designed to control the virtual image distance from 20 mm in front of a viewer to the infinity as the distance from the viewer. As a result, the “mismatch problem with vergence distance and accommodation distance” (see the first embodiment and
In a virtual image display method according to an embodiment of the present disclosure, a correction process is performed on images that is displayed on the respective image forming elements by taking into consideration the optical characteristics of the first to N-th eyepiece optical systems such as aberration and peripheral darkening, darkening caused by vignetting of a pencil of light rays that is geometrically determined from the pupil position and the pupil diameter of a viewer and the position and the inclination angle of a boundary surface in the eyepiece optical systems, further the light emission characteristics of the first to N-th image forming elements such as light distribution, chromaticity, and spectra, and the like (see the first embodiment,
Such a method makes it possible to seamlessly join a plurality of virtual images that is outputted from the first to N-th eyepiece optical systems and alleviate the risk that the borders between a plurality of images are visually recognized.
More desirably, the correction process on images that are displayed on the first to N-th image forming elements is adjusted in real time in accordance with of eyeball rotation accompanying the line-of-sight movement of a viewer while the line-of-sight direction of the viewer is detected. The correction process of seamlessly joining a plurality of virtual images varies in accordance with the state of eyeball rotation. Such a method thus makes it possible to alleviate the risk that the border between a plurality of images is visually recognized even in a case where a viewer moves the line of sight.
In addition, in the virtual image display method according to the embodiment, the virtual image distance from an observer to each of virtual image surfaces by the first to N-th eyepiece optical systems may be controlled in accordance with a viewer's angle of vergence by sliding the position of a component in each of the first to N-th eyepiece optical systems or the position of each of the first to N-th image forming elements with a sliding mechanism while the line-of-sight direction of the viewer is detected. In addition, images that are displayed on the first to N-th image forming elements may be adjusted at the display positions corresponding to the magnification of the first to N-th eyepiece optical systems and an observer's angle of vergence and a display object that is out of the vergence distance and the viewer is not gazing at may be corrected to be subjected to a blur process in conjunction with the operation of the sliding mechanism (see the first embodiment,
Such a method solves the “mismatch problem with vergence distance and accommodation distance” of a typical virtual image display apparatus and makes a viewer feel less uncomfortable or less sick in viewing, for example. In addition, such a method makes it possible to seamlessly join together the first to N-th virtual images that are outputted from the first to N-th eyepiece optical systems and output a virtual image having a natural sense of depth.
The following describes the specific first to fifth embodiments of the head-mounted virtual image display apparatus and the virtual image display method according to the respective embodiments of the present disclosure described above in detail with reference to the drawings where appropriate. It is to be noted that, in this specification and the drawings, components that have substantially the same functional configuration are denoted with the same section numbers and repeated description is thus omitted.
A head-mounted virtual image display apparatus according to the first embodiment includes an optical unit for a left eye 30L and an optical unit for a right eye 30R. In the first embodiment and the second to fifth embodiments described below, a configuration of the optical unit for the right eye 30R is primarily described as an example. A configuration of the optical unit for the left eye 30L is, however, basically the same as that of the optical unit for the right eye 30R.
In the head-mounted virtual image display apparatus according to the first embodiment, the optical unit for the left eye 30L and the optical unit for the right eye 30R each include a plurality of image forming elements including first to fourth image forming elements 11 to 14 (see
The first image forming element 11 is a high-definition and small image forming element. The first image forming element 11 displays an image that is outputted to the front region in the visual field of a viewer. The first image forming element 11 has, for example, a pixel pitch of 7.8 μm, a diagonal size of 1 inch, a horizontal pixel count of 2500 pixels, and a vertical pixel count of 2080 pixels. The first image forming element 11 is, for example, M-OLED
The second image forming element 12 is disposed on the right side of the first image forming element 11. The second image forming element 12 displays an image that is outputted to the right peripheral region in the visual field of a viewer. The pixel pitch of the second image forming element 12 is greater than that of the first image forming element 11. The second image forming element 12 has, for example, a pixel pitch of 65.25 μm and a diagonal size of 1.65 inches. In addition, the second image forming element 12 has, for example, a horizontal pixel count of 300 pixels and a vertical pixel count of 550 pixels. The second image forming element 12 is, for example, LTPS (Low Temperature Polycrystalline Silicon)-OLED. It is to be noted that the second image forming element 12 is disposed on the left side of the first image forming element 11 in a case of the optical unit for the left eye 30L. The second image forming element 12 displays an image that is outputted to the left peripheral region in the visual field of a viewer.
The third image forming element 13 is disposed on the upper side of the first image forming element 11. The third image forming element 13 displays an image that is outputted to the upper peripheral region in the visual field of a viewer. The fourth image forming element 14 is disposed on the lower side of the first image forming element 11. The fourth image forming element 14 displays an image that is outputted to the lower peripheral region in the visual field of a viewer. The pixel pitch of each of the third and fourth image forming elements 13 and 14 is greater than that of the first image forming element 11. The third and fourth image forming elements 13 and 14 each have, for example, a pixel pitch of 65.25 μm. The third and fourth image forming elements 13 and 14 each have, for example, a diagonal size of 1.55 inches. The third and fourth image forming elements 13 and 14 each have, for example, a horizontal pixel count of 525 pixels and a vertical pixel count of 260 pixels. Each of the third and fourth image forming elements 13 and 14 is, for example, LTPS-OLED.
In the optical unit for the right eye 30R, the field angle region of the first image 11R displayed by the first image forming element 11 has, for example, a horizontal field angle within a range of −40° or more and 40° or less and a vertical field angle within a range of −30° or more and 30° or less. In addition, in the optical unit for the right eye 30R, the field angle region of the second image 12R displayed by the second image forming element 12 has a horizontal field angle within a range of 25° or more and 75° or less and a vertical field angle within a range of −50° or more and 50° or less. In addition, in the optical unit for the right eye 30R, the field angle region of the third image 13R displayed by the third image forming element 13 has a horizontal field angle within a range of −40° or more and 55° or less and a vertical field angle within a range of 15° or more and 50° or less. In addition, in the optical unit for the right eye 30R, the field angle region of the fourth image 14R displayed by the fourth image forming element 14 has a horizontal field angle within a range of −40° or more and 55° or less and a vertical field angle within a range of −50° or more and −15° or less.
In addition, in the optical unit for the left eye 30L, the field angle region of the first image 11L that is displayed by the first image forming element 11 has a horizontal field angle within a range of −40° or more and 40° or less and a vertical field angle within a range of −30° or more and 30° or less. In addition, in the optical unit for the left eye 30L, the field angle region of the second image 12L that is displayed by the second image forming element 12 has a horizontal field angle within a range of −75° or more and −25° or less and a vertical field angle within a range of −50° or more and 50° or less. In addition, in the optical unit for the left eye 30L, the field angle region of the third image 13L displayed by the third image forming element 13 has a horizontal field angle within a range of −55° or more and 40° or less and a vertical field angle within a range of 15° or more and 50° or less. In addition, in the optical unit for the left eye 30L, the field angle region of the fourth image 14L displayed by the fourth image forming element 14 has a horizontal field angle within a range of −40° or more and 55° or less and a vertical field angle within a range of −50° or more and −15° or less.
The first image forming element 11 in the optical unit for the right eye 30R and the first image forming element 11 in the optical unit for the left eye 30L display equal field angle regions. In addition, the optical units for the left eye 30L and the right eye 30R superimpose field angle regions each having a horizontal field angle of −40° or more and 40° or less and a vertical field angle of −50° or more and 50° or less. These field angle regions are effective in providing a viewer with depth perception by using parallax images. Further, two given adjacent images are disposed to have superimposed regions each having a field angle of at least 15° or more.
There is a region referred to as discriminative visual field in which humans exhibits an excellent visual function in the central portion of the visual field, that is, the line-of-sight direction. This angle region has a range of ±2.5°. In addition, the region having a horizontal range of ±15° and a vertical range of −12° or more and 8° or less is referred to as effective visual field. Humans are able to instantly identify information just by moving the eyes. Different between individuals, humans each have the region having a horizontal range of −45° to −30° or more and 30° to 45° or less and a vertical range of −40° to −25° or more and 20° to 30° or less outside the effective visual field. This region is referred to as stable gazing field. Humans are each able to effectively identify information by a line-of-sight movement achieved by moving the eyes or moving the head. Further, the peripheral visual field outside the stable gazing field includes regions referred to as inductive visual field and auxiliary visual field. In any of them, humans exhibit low information discrimination capability.
If the visual field characteristics illustrated in
The first eyepiece optical system 21 includes a first L1 lens L11 and a first L2 lens L12. The second eyepiece optical system 22 includes a second L1 lens L21 and a second L2 lens L22. The third eyepiece optical system 23 includes a third L1 lens L31 and a third L2 lens L32. The fourth eyepiece optical system 24 includes a fourth L1 lens L41 and a fourth L2 lens L42.
There is a boundary surface 72 between the first eyepiece optical system 21 and the second eyepiece optical system 22. There is a boundary surface 73 between the first eyepiece optical system 21 and the third eyepiece optical system 23. There is a boundary surface 74 between the first eyepiece optical system 21 and the fourth eyepiece optical system 22.
It is to be noted that regions outside the effective diameters of the respective lenses may be cut-off regions 61 to 64 of the lenses.
In the first embodiment, each of the first to fourth eyepiece optical systems is optically designed to adopt a Fresnel lens as each of the opposed surfaces of the L1 lens and the L2 lens. This makes it possible to achieve a reduction in optical unit height and weight and further achieve a reduction in apparatus height and weight as a whole as compared with an optical design in which only a standard spherical lens and a standard aspherical lens are adopted.
In
It is to be noted that the design of
It is to be noted that the designs of the position of the boundary surface 72 between two eyepiece optical systems which are adjacent in the horizontal direction have been described so far with reference to
In
It is to be noted that the design of
In addition, to reduce the vignetting of a pencil of light rays, it is desirable that a lens end surface in contact with boundary surface 72 have less surface area. The design in which a Fresnel lens is used is superior because it is easy to reduce a lens in height as with the first embodiment.
Further, as the boundary surface between two given adjacent eyepiece optical systems, the individually formed lenses may be separately grasped or bonded and fixed. Alternatively, the lenses may be integrally formed with the lens surfaces discontinuously shaped. In a case where individually formed lenses are used, the lens end surfaces on the boundary surface may be subjected to a sand blasting process or a blacking-out process to prevent stray light. A light-shielding sheet may be inserted to the boundary surface or a light-shielding mask may be added at an effective position. In contrast, in a case where stray light does not take a path leading into an eye, no countermeasures have to be particularly taken.
It is to be noted that the designs of the inclination angle of the boundary surface between two given eyepiece optical systems which are adjacent in the horizontal direction have been described so far with reference to
It is to be noted that the designs of virtual image surfaces in the horizontal direction have been described so far with reference to
To solve the “mismatch problem with vergence distance and accommodation distance”, the head-mounted virtual image display apparatus according to the first embodiment includes a sliding mechanism 90 (see (B) of
It is to be noted that only the first image forming element 11 is configured to slide in the design examples of
The optical designs of the head-mounted virtual image display apparatus according to the first embodiment have been described so far. To seamlessly join together images separately displayed by the first to fourth image forming elements 11 to 14, appropriate image processing is necessary. In the virtual image display method according to the first embodiment, a correction process is performed on images by taking into consideration the optical characteristics of the respective eyepiece optical systems such as aberration and peripheral darkening. The images are displayed on the respective image forming elements. In addition, a correction process is performed on images by taking into consideration the characteristics of a pencil of light rays such as darkening caused by the vignetting of the pencil of light rays, further the light emission characteristics of the first to fourth image forming elements 11 to 14 such as light distribution, chromaticity, and spectra, and the like. The images are displayed on the respective image forming elements. The characteristics of the pencil of light rays are geometrically determined from the pupil position and the pupil diameter of a viewer and the position and the inclination angle of the boundary surface in the eyepiece optical systems. The head-mounted virtual image display apparatus according to the first embodiment may include a display image correction section 45 that performs this correction process (see
Here, the correction process varies in accordance with the state of eyeball rotation. It is therefore desirable that the correction process be adjusted in real time by detecting the line-of-sight direction of a viewer. To detect the line-of-sight direction of a viewer, it is sufficient if an infrared light source is disposed in front of an eye and an imaging device including a lens barrel and an imaging element simultaneously shoots a corneal reflection image of the light source and an image of a pupil to identify the line-of-sight direction from the relative positional relationship (pupil center corneal reflection). The infrared light source does not affect viewing. It is then desirable to shoot images from the direction points to the right front of the eye as much as possible to increase the detection accuracy of the line-of-sight direction. In the present embodiment, the first image forming element 11 is, however, small. This increases the volume density of lenses in the first eyepiece optical system 21. It is possible to dispose the imaging device in limited space.
It is to be noted that (A) and (B) of
In contrast, in
It is to be noted that (C) of
In addition, an imaging device may also be included that shoots a landscape image of the outside. This may allow for a configuration in which it is possible, for example, to display the landscape image of the outside shot by the imaging device.
Such a method solves the “mismatch problem with vergence distance and accommodation distance” and makes a viewer feel less uncomfortable or less sick in viewing, for example. It is to be noted that a control mechanism for virtual image distance shifts a single virtual image surface back and forth and it is not possible to output a three-dimensional surface in real space. However, human eyes originally have accommodation distance for a gazing point. Even the virtual image display method described above causes no problem.
As described above, the head-mounted virtual image display apparatus and the virtual image display method according to the first embodiment make it possible to achieve relative smallness and light weight and achieve both high resolution and a wide viewing angle while suppressing manufacturing cost. This makes it possible to provide a viewer with comfortable wearability and a sense of immersion.
It is to be noted that the effects described in this specification are merely illustrative and non-limiting. In addition, there may be any other effect. This also holds true for the effects of the following other embodiments.
Next, a head-mounted virtual image display apparatus and a virtual image display method according to a second embodiment of the present disclosure are described. It is to be noted that the following denotes components which are substantially the same as those of the head-mounted virtual image display apparatus and the virtual image display method according to the first embodiment described above with the same signs and omits the description thereof where appropriate.
The first image forming element 11 is a high-definition and small image forming element. The first image forming element 11 displays an image that is outputted to the front region in the visual field of a viewer. In a case of the second embodiment, the first image forming element 11 has a pixel pitch of 10.6 μm, a horizontal pixel count of 2260 pixels, and a vertical pixel count of 2560 pixels. The first image forming element 11 is, for example, M-OLED.
The second image forming element 12 is disposed on the right side of the first image forming element 11. The second image forming element 12 displays an image that is outputted to the right peripheral region in the visual field of a viewer. The second image forming element 12 has a greater pixel pitch than that of the first image forming element 11. The second image forming element 12 has a pixel pitch of 65.25 μm, a horizontal pixel count of 400 pixels, and a vertical pixel count of 750 pixels. The second image forming element 12 is, for example, LTPS-OLED.
The first and second eyepiece optical systems 21 and 22 are designed to be able to output field angle regions separately displayed by the first and second image forming elements 11 and 12. The optical unit for the right eye 30R outputs, as a whole, a virtual image having a horizontal field angle within a range of −55° or more and 75° or less.
The first eyepiece optical system 21 includes the first L1 lens L11, the first L2 lens L12, and the first L3 lens L12. In addition, the opposed surfaces of the first L1 lens L11 and the first L2 lens L12 are both optically designed as Fresnel lenses. This makes it possible to achieve a reduction in optical unit height and weight and further achieve a reduction in apparatus height and weight as a whole as compared with an optical design in which only a standard spherical lens and a standard aspherical lens are adopted.
In the optical unit for the right eye 30R, the second eyepiece optical system 22 that outputs a virtual image to a peripheral region in the visual field of a viewer includes a second L1 lens L21 and a second L2 lens L22. In addition, the second L2 lens L22 is optically designed as one-surface reflection type free-form surface prism.
Such a configuration assumes that a viewer wears a virtual image display apparatus with glasses on. Such a configuration prevents the apparatus from increasing in size as a whole and facilitates a design in which sufficient space is secured in front of the eyes (space from the face of a viewer to the lens surface that is the closest to the eyes).
The other configurations, operations, and effects may be substantially similar to those of the head-mounted virtual image display apparatus and the virtual image display method according to the first embodiment described above.
Next, a head-mounted virtual image display apparatus and a virtual image display method according to a third embodiment of the present disclosure are described. It is to be noted that the following denotes components which are substantially the same as those of the head-mounted virtual image display apparatus and the virtual image display method according to the first or second embodiment described above with the same signs and omits the description thereof where appropriate.
The first and second eyepiece optical systems 21 and 22 are designed to be able to output field angle regions separately displayed by the first and second image forming elements 11 and 12. The optical unit for the right eye 30R outputs, as a whole, a virtual image having a horizontal field angle within a range of −45° or more and 70° or less.
The first eyepiece optical system 21 includes the first L1 lens L11, the first L2 lens L12, and a first L3 lens L13. In addition, the opposed surfaces of the first L1 lens L11 and the first L2 lens L12 are both optically designed as Fresnel lenses. This makes it possible to achieve a reduction in optical unit height and weight and further achieve a reduction in apparatus height and weight as a whole as compared with an optical design in which only a standard spherical lens and a standard aspherical lens are adopted.
In the optical unit for the right eye 30R, the second eyepiece optical system 22 that outputs a virtual image to a peripheral region in the visual field of a viewer includes the second L1 lens L21 that is optically designed as a two-surface reflection type free-form surface prism.
Such a configuration also allows for a design in which a heated portion is put away from the face of a viewer in a case where there is a concern that heat is generated from the second image forming element 12, a control circuit (not illustrated) for the second image forming element 12, and the like.
The head-mounted virtual image display apparatus according to the third embodiment does not have the boundary surface 72 between the first eyepiece optical system 21 and the second eyepiece optical system 22. It is a lens cut surface 161 that is at the position corresponding to the boundary surface 72 in the first eyepiece optical system 21. It is preferable that the position and the inclination angle of the lens cut surface 161 in the first eyepiece optical system 21 be designed as with the position and the inclination angle of the boundary surface 72 between the first and second eyepiece optical systems 21 and 22 according to the first embodiment.
The other configurations, operations, and effects may be substantially similar to those of the head-mounted virtual image display apparatus and the virtual image display method according to the first embodiment described above.
Next, a head-mounted virtual image display apparatus and a virtual image display method according to a fourth embodiment of the present disclosure are described. It is to be noted that the following denotes components which are substantially the same as those of the head-mounted virtual image display apparatus and the virtual image display method according to any of the first to third embodiments described above with the same signs and omits the description thereof where appropriate.
The first and second eyepiece optical systems 21 and 22 are designed to be able to output field angle regions separately displayed by the first and second image forming elements 11 and 12. The optical unit for the right eye 30R outputs, as a whole, a virtual image having a horizontal field angle within a range of −45° or more and 70° or less.
The first eyepiece optical system 21 includes the first L1 lens L11, the first L2 lens L12, and the first L3 lens L13. In addition, the opposed surfaces of the first L1 lens L11 and the first L2 lens L12 are both optically designed as Fresnel lenses. This makes it possible to achieve a reduction in optical unit height and weight and further achieve a reduction in apparatus height and weight as a whole as compared with an optical design in which only a standard spherical lens and a standard aspherical lens are adopted.
In the optical unit for the right eye 30R, the second eyepiece optical system 22 that outputs a virtual image to a peripheral region in the visual field of a viewer includes a second M1 mirror M21 that is optically designed as a relatively simple free-form surface mirror.
Such a configuration allows for a design in which a heated portion is put away from the face of a viewer in a case where there is a concern that heat is generated from the second image forming element 12, a control circuit (not illustrated) for the second image forming element 12, and the like.
The head-mounted virtual image display apparatus according to the fourth embodiment does not have the boundary surface 72 between the first eyepiece optical system 21 and the second eyepiece optical system 22. It is the lens cut surface 161 that is at the position corresponding to the boundary surface 72 in the first eyepiece optical system 21. It is preferable that the position and the inclination angle of the lens cut surface 161 in the first eyepiece optical system 21 be designed as with the position and the inclination angle of the boundary surface 72 between the first and second eyepiece optical systems 21 and 22 according to the first embodiment.
The other configurations, operations, and effects may be substantially similar to those of the head-mounted virtual image display apparatus and the virtual image display method according to the first embodiment described above.
Next, a head-mounted virtual image display apparatus and a virtual image display method according to a fifth embodiment of the present disclosure are described. It is to be noted that the following denotes components which are substantially the same as those of the head-mounted virtual image display apparatus and the virtual image display method according to any of the first to fourth embodiments described above with the same signs and omits the description thereof where appropriate.
The first and second eyepiece optical systems 21 and 22 are designed to be able to output field angle regions separately displayed by the first and second image forming elements 11 and 12. The optical unit for the right eye 30R outputs, as a whole, a virtual image having a horizontal field angle within a range of −50° or more and 75° or less.
The first eyepiece optical system 21 includes the first L1 lens L11, the first L2 lens L12, the first L3 lens L13, and a first L4 lens L14.
The second eyepiece optical system 22 includes the second L1 lens L21, the second L2 lens L22, and a second L3 lens L23. Further, in the first and second eyepiece optical systems 21 and 22, the respective L1 lenses (first L1 lens L11 and second L1 lens L21) are optically designed to be shared as the same lens.
In general, a lens surface farther from an eye varies less in light ray height along with eyeball rotation. Thus, dividing the second or subsequent lens group from the eye side causes a pencil of light rays to have less vignetting than vignetting caused by dividing the first and subsequent lenses from the eye side. This makes it possible to reduce superimposed regions that are set for two adjacent images. It is thus possible to increase the use efficiency of the pixels included in the first and second image forming elements 11 and 12.
Further, in the configuration of the eyepiece optical systems according to the fifth embodiment, the L1 lens is common to the first and second eyepiece optical systems 21 and 22. No ridge line is thus formed on the lens surface. This also alleviates the risk that a ridge line is visually recognized on the L1 lens.
The head-mounted virtual image display apparatus according to the fifth embodiment does not have the boundary surface 72 between the first eyepiece optical system 21 and the second eyepiece optical system 22. It is the lens cut surface 161 that is at the position corresponding to the boundary surface 72 in the first eyepiece optical system 21. It is preferable that the position and the inclination angle of the lens cut surface 161 in the first eyepiece optical system 21 be designed as with the position and the inclination angle of the boundary surface 72 between the first and second eyepiece optical systems 21 and 22 according to the first embodiment.
The other configurations, operations, and effects may be substantially similar to those of the head-mounted virtual image display apparatus and the virtual image display method according to the first embodiment described above.
The technology according to the present disclosure is not limited to the descriptions of the respective embodiments described above, but may be modified in a variety of ways.
For example, the present technology may also have configurations as follows.
The present technology having the following configurations makes it possible to provide a viewer with comfortable wearability and a sense of immersion.
(1)
A virtual image display apparatus including:
a plurality of image forming elements including a first image forming element and a second image forming element, the first image forming element outputting a first image to a front region in a visual field of a viewer, the second image forming element outputting a second image to a peripheral region in the visual field of the viewer, the second image being different from the first image, the plurality of image forming elements outputting a plurality of images to cause an image region of at least a portion of each of the plurality of images to overlap with the first image, the plurality of images including the first and second images; and
a plurality of eyepiece optical systems that is provided in association with the plurality of respective image forming elements, the plurality of eyepiece optical systems forming one virtual image as a whole from the plurality of images.
(2)
The virtual image display apparatus according to (1), in which the first image is higher than the second image in resolution.
(3)
The virtual image display apparatus according to (1) or (2), in which
the plurality of eyepiece optical systems includes a first eyepiece optical system that is provided in association with the first image forming element, and
the first eyepiece optical system is configured to output a virtual image having 60° or more and 120° or less as a horizontal field angle and 45° or more and 100° or less as a vertical field angle.
(4)
The virtual image display apparatus according to any one of (1) to (3), in which the first image forming element has a resolution of 2000 ppi or more and the second image forming element has a resolution of less than 2000 ppi.
(5)
The virtual image display apparatus according to any one of (1) to (4), in which a position of a boundary surface between two given adjacent eyepiece optical systems is designed in the plurality of eyepiece optical systems to join two given adjacent virtual images with no gap while causing the two given adjacent virtual images to constantly have partially overlapping regions in spite of a line-of-sight movement of the viewer, the two given adjacent virtual images being outputted from the two respective given adjacent eyepiece optical systems.
(6)
The virtual image display apparatus according to any one of (1) to (5), in which an inclination angle of a boundary surface between two given adjacent eyepiece optical systems is designed in the plurality of eyepiece optical systems to suppress vignetting of a pencil of light rays for a line-of-sight movement of the viewer, the pencil of light rays passing by near the boundary surface.
(7)
The virtual image display apparatus according to any one of (1) to (6), in which the plurality of eyepiece optical systems is configured to form a smoothly curved virtual image surface as a whole to cover the viewer's field of vision or form a discretely curved virtual image surface as a whole to cover the viewer's field of vision by causing an eyepiece optical system disposed closer to a periphery to form a more inclined virtual image surface while each of the eyepiece optical systems forms a flat virtual image surface.
(8)
The virtual image display apparatus according to any one of (1) to (7), in which at least one eyepiece optical system of the plurality of eyepiece optical systems includes a Fresnel lens.
(9)
The virtual image display apparatus according to any one of (1) to (8), in which one eyepiece optical system of the plurality of eyepiece optical systems is configured by using an optical scheme that is different from an optical scheme of another eyepiece optical system.
(10)
The virtual image display apparatus according to (9), in which the other eyepiece optical system is configured by using an optical scheme in which a free-form surface prism or a free-form surface mirror is included.
(11)
The virtual image display apparatus according to any one of (1) to (7), in which at least a surface positioned closest to an eye side of the viewer in the plurality of eyepiece optical systems serves as a lens surface shared between the respective eyepiece optical systems.
(12)
The virtual image display apparatus according to any one of (1) to (11), further including a sliding mechanism configured to control virtual image distance from the observer to a virtual image surface by each of the plurality of eyepiece optical systems by sliding a position of a component in each of the plurality of eyepiece optical systems or a position of each of the plurality of image forming elements.
(13)
The virtual image display apparatus according to (12), in which the sliding mechanism is configured to control the virtual image distance from 20 mm in front of the viewer to infinity.
(14)
A virtual image display method including:
a step of displaying a plurality of images by a plurality of respective image forming elements;
a step of outputting the plurality of images via a plurality of eyepiece optical systems corresponding to the plurality of respective image forming elements; and
a step of correcting images that are displayed on the plurality of image forming elements on the basis of at least one of optical characteristics of the plurality of eyepiece optical systems, characteristics of a pencil of light rays, or light emission characteristics of the plurality of image forming elements to cause images outputted via the plurality of eyepiece optical systems to form the one virtual image, the characteristics of the pencil of light rays being geometrically determined from a pupil position and a pupil diameter of the viewer and a position and an inclination angle of a boundary surface in the eyepiece optical systems.
(15)
The virtual image display method according to (14), in which
the optical characteristics include characteristics of the plurality of eyepiece optical systems regarding aberration and peripheral darkening, and
the light emission characteristics include characteristics of the plurality of image forming elements regarding light distribution, chromaticity, and spectra.
(16)
The virtual image display method according to (14) or (15), further including a step of adjusting the correction on the images in accordance with a line-of-sight direction of the viewer, the images being displayed on the plurality of image forming elements.
(17)
The virtual image display method according to any one of (14) to (16), further including:
a step of controlling virtual image distance from the observer to a virtual image surface by each of the plurality of eyepiece optical systems in accordance with the viewer's angle of vergence while detecting a line-of-sight direction of the viewer by sliding a position of a component in each of the plurality of eyepiece optical systems or a position of each of the plurality of image forming elements with a sliding mechanism; and
a step of, in conjunction with an operation of the sliding mechanism, adjusting the images that are displayed on the plurality of image forming elements at display positions corresponding to magnification of the plurality of eyepiece optical systems and the observer's angle of vergence and performing correction to subject a display object at which the viewer is not gazing to a blur process, the display object being out of vergence distance.
The present application claims priority based on Japanese Patent Application No. 2018-211365 filed with Japan Patent Office on Nov. 9, 2018 and Japanese Patent Application No. 2019-040813 filed with Japan Patent Office on Mar. 6, 2019, the entire contents of each which are incorporated herein by reference.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-211365 | Nov 2018 | JP | national |
| 2019-040813 | Mar 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/037259 | 9/24/2019 | WO | 00 |
