Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
AiARATUS Aril) IVIETIIIOD FORAinOFrIC REAL Tir VIDEOSYSTEM
CROSS-REFERENCE TO RELATED APPLICATIONS
[001] This application claims the benefit of priority as a divisional of CA
2,875,261 which
was filed December 1, 2014 entitled "Apparatus and Method for a Bioptic Real
Time Video
System", which itself claims priority as a national phase entry of World
Intellectual Property
Office PCT/CA2012/000532 filed June 1, 2012 entitled "Apparatus and Method for
a Bioptic
Real Time Video System."
FIELD OF THE INVENTION
[002] The invention relates generally to the field of wearable electronic
displays and more
specifically to the field of vision care.
BACKGROUND OF THE INVENTION
[003] There are numerous applications for lightweight head-worn near-to-eye
displays.
These are commonly called Head Mounted Displays (HMD). HMDs display to the eye
an
electronically rendered image such that the wearer perceives that they are
watching a sizeable
electronic display at some distance in front of them. The applications that
use such HMDs are
numerous, including but not limited to virtual reality, electronic gaming,
simulation
environments such as for military simulations or flight simulators, medical
applications such
as for the enhancement of sight, and consumer applications such as the ability
to view videos
in a mobile setting.
[004] One of the fundamental challenges of HMDs is the tradeoff between the
display's
Field of View (FOV), being the size of the virtual display as perceived by the
wearer, and
pixel size. FOV is normally defined as the number of angular degrees subtended
within the
viewer's overall field of vision, horizontally, vertically, or on the
diagonal. Horizontal FOV
dimensions in the range of 20-30 degrees are typical, with larger dimensions
being possible at
significant expense. Pixel size is similarly expressed as the number of
angular arc minutes
(1/60th of a degree) subtended by a single, typically square pixel element. As
one might
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expect, to achieve a larger FOV with a given pixel resolution (number of
pixels), results in a
larger pixel size, and consequent loss of image detail.
1005] Peripheral vision is that portion of the human field of vision outside
the center, say,
10-15 degrees FOV. Peripheral vision is extremely important in some HMD
applications,
especially those in which the wearer must maintain a connection with their
natural
environment to contextualize their situation, and enable way finding,
orientation, and
mobility. To provide significant peripheral vision via the electronic display
requires an
extremely large (and expensive) HMD. Alternately HMDs which provide a
significant natural
peripheral vision external to the HMD housing, provide a very limited virtual
electronic
FOV.
[006] Many HMD applications can benefit from the incorporation of a live
camera into the
HMD, such that the wearer can not only view electronic data from a source,
such as a video
file, but also live video images of the world in front of them. Image
processing can be used to
enhance the live camera image before it is presented to the eye, providing
magnification,
enhancement of brightness, or improved contrast for example.
[007] In HMD systems that are to be used for multiple activities, different
camera angles
may be required for different tasks. For example, to observe an object a
distance, the camera
angle should be nearly horizontal relative to the horizon when the wearer's
neck is straight,
and their gaze angled at the horizon. On the other hand, to view hand-held
objects at a close
distance requires a camera that is angled downward, in order to avoid a highly
exaggerated
downward neck posture. In this manner, the angle of the camera mimics the
angular
movement of one's eyes in a non-HMD world.
[008] Finally, the angle of the display relative to the eyes is also dependent
on the specific
tasks of the wearer. In certain situations, the wearer would like to look into
the electronic
display only temporarily, and by looking up at an angle higher than their
habitual gaze. In
other situations, the wearer would prefer a more immersive usage model, where
the electronic
display is directly in front of their normal line of gaze.
[009] What is needed then is a general HMD device that is capable of providing
significant
unobstructed peripheral vision outside of the electronic display FOV, while
simultaneously
providing a high resolution video image. Further, the ability to adjust the
angle of the display
and the camera according to the wearer's specific activity would provide
significant comfort
and increased usability.
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[0010] Other aspects and features of the present invention will become
apparent to those
ordinarily skilled in the art upon review of the following description of
specific embodiments
of the invention in conjunction with the accompanying figures.
SUMMARY OF THE INVENTION
[0011] The ability to quickly alternate as required by the specific task,
between viewing an
image presented in the electronic display and viewing the world without the
electronic
display, enables many possible usage models for an HMD. Furthermore, in an HMD
with an
integrated camera, the ability to adjust the vertical camera angle for
different tasks, viewing
objects distant and close for example, significantly increases the usability
of such a device.
Finally, an HMD whereby the user is able to select the vertical position of
the electronic
display, in order to tradeoff a comfortable immersive video experience versus
maintaining a
broad natural field of view enables the HMD to be used in a variety of user
applications and
postures.
[0012] The invention, in one aspect, relates to a method of orienting an
electronic near-to-eye
display such that the wearer views it slightly above their habitual line of
sight for a given
task. In this manner the wearer, through slight neck and eye angle adjustments
can, with
minimal effort, alternate between the electronic display and their natural
vision.
[0013] In one embodiment, the electronic display is mounted slightly above the
wearer's
habitual line of sight, so that by angling the neck slightly forward and
directing their gaze
slightly upward, they can look into the display. Alternately by angling the
neck slightly back
and directing their gaze slightly down, they can view below the electronic
display using their
natural vision.
10014] In another embodiment, the apparatus incorporates the wearer's
prescription
ophthalmic lenses, so that whether they gaze up into the electronic HMD or
down using their
natural vision, they are able to do so through their prescription lenses. This
embodiment of
the invention alleviates the need to switch between the HMD device and the
wearer's habitual
spectacles.
[0015] In another embodiment the apparatus incorporates a video camera, which
provides the
video information to the electronic display, the angle of the camera being
adjustable as
required by the specific task.
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[0016] In any of the above embodiments the source of the video may come from a
device
other than the camera, in any standard electronic video format such as MPEG
for example.
[0017] In another embodiment the apparatus may deploy motion sensing
components in
order to facilitate image stabilization for the electronic video image that is
captured by the
camera.
[0018] In another embodiment the motion sensing components could be used to
determine
the angular orientation of the apparatus, so that the vertical camera angle
can be
automatically adjusted based on head position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention is pointed out with particularity in the appended claims.
The
advantages of the invention described above, together with further advantages,
may be better
understood by referring to the following description taken in conjunction with
the
accompanying drawings. In the drawings, like reference characters generally
refer to the
same parts throughout the different views. The drawings are not necessarily to
scale,
emphasis instead generally being placed upon illustrating the principles of
the invention.
[0020] FIGS. 1 through 4 are highly schematic diagrams of an embodiment of the
system of
the invention;
[0021] FIG. 5 is a more detailed view of an embodiment of the system for
automatically
adjusting the angle of the camera.
[0022] FIG. 6 is a more realistic rendering of a particular embodiment of the
system of the
invention.
[0023] FIGS. 7A through 7C depict three successive frames of simulated video,
in order to
show how motion vectors can be used for image stabilization.
[0024] FIGS. 8A and 8B show an alternate method of altering the camera angle
through
defining a window on the image sensor rather than by physically altering the
camera angle.
DETAILED DESCRIPTION
[0025] In brief overview and referring to FIG. 1 and FIG. 6, the system in one
embodiment
includes prescription lenses 6 mounted to an eyeglasses frame 1. The Head
Mounted Display
portion of the system comprises a housing 2, which can move relative to the
eyeglasses frame
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1, about a pivot point 3. The HMD housing 2 incorporates HMD optics 5, a
camera 9, and
HMD electronics 8 (collectively, the "HMD").
[0026] In the orientation depicted in FIG. 1, the wearer's head/neck posture
is angled slightly
back 4, and he is viewing the world 7 through the prescription lens 6, without
the use of the
HMD optics 5 or camera 9.
[0027] In FIG. 2, the head/neck angle 4 is slightly forward, allowing the user
to view the
HMD optics 5 through the same prescription lens 6 by directing their gaze at a
slight upward
angle 7. In this mode, video information viewed through the HMD optics 5 can
be provided
from the video camera 9, oriented at an outward angle 10 such that objects at
a distance can
be viewed in the video image. As discussed, the video could also come from
other sources.
[0028] In FIG. 3 the head/neck angle 4 is unchanged from FIG. 2, but the
camera has been
angled downward on a pivot point 11 so that the camera angle 10 is now aimed
at a nearby
object close at hand, perhaps in the wearer's hands.
[0029] In FIG. 4 the slightly forward head/neck angle 4 remains unchanged, but
the HMD
angle has been significantly lowered by pivoting the HMD housing 2 relative to
the
eyeglasses frame 1, around a pivot point 3. In this orientation the wearer is
able to adopt a
more comfortable viewing angle 7 for near-in tasks. Furthermore, the camera
angle 10 can be
directed further downward because the camera pivot point 11 moves with the HMD
housing
2.
[0030] In FIG. 5, a method is shown whereby a linear motor 12 can be used to
adjust the
vertical angle 10 of the camera 9. The camera rotated around a pivot point 11
that is affixed
to the HMD housing 2. With the adjustment of the camera angle automated thus,
it is possible
to use motion and position sensors embodied in the HMD electronics 8, to
provide positional
data that can be used to control the linear motor 12.
[0031] Alternately, the angle 10 of the camera 9 can be adjusted manually by
the user.
[0032] FIG. 7 shows how the same motion and position sensors embodied in the
HMD
electronics 8 can be used to enable an image stabilization function. FIGS. 7A,
7B, and 7C
show three consecutive frames of video as captured by the camera 9. Because of
the normal
movement of the wearer's head, successive frames of video have a translational
(up/down,
left/right) and rotational (angular) position relative to the previous frame.
The frame depicted
in FIG. 7B for example has shifted to the right/down and rotated slightly
counter-clockwise
relative to the previous frame 7A. The translational vector Al and rotational
angle 01 can be
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determined from the motion and position sensors embodied in the HMD
electronics 8. By
applying the opposite of the translational vector and the reverse rotational
angle to the pixels
in the video frame 7B, the differences between the two frames 7A and 7B can be
removed.
FIG. 7C carries the example further, showing a frame of video that is now
shifted left/down
and clockwise relative to the previous frame 7B. A new vector A2 and
rotational angle 02 can
be applied, and so forth so that over time, small frame-to-frame variations
caused by the
wearer's head movement are removed from the displayed video. To distinguish
between
minor head movements, for which image stabilization should be applied, and
gross head
movements, which indicate the wearer's scene of interest has changed, requires
that the image
stabilization function only be applied to small translational and rotational
vectors.
[0033] In FIGS. 8A and 8B, the angle of the camera 9 is adjusted not by
physically rotating
the camera as previously discussed. Rather, an area of pixels, or a window 13,
14 can be
defined on the image sensor so that the wearer perceives that the camera angle
is physically
altered. This technique requires a camera system wherein the usable image
sensor area is
larger than the video that is to be displayed to the wearer. Motion and
position sensors
embodied in the HMD electronics 8 can be used to determine the wearer's
head/neck angle 4
and, based on this information, define a capture window 13, 14 that gives the
wearer the
perception of a high or low camera angle 10.
[0034] While the present invention has been described in terms of certain
exemplary
preferred embodiments, it will be readily understood and appreciated by one of
ordinary skill
in the art that it is not so limited, and that many additions, deletions and
modifications to the
preferred embodiments may be made within the scope of the invention as
hereinafter claimed.
Accordingly, the scope of the invention is limited only by the scope of the
appended claims.
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