U.S. patent application number 09/895576 was filed with the patent office on 2001-11-01 for portable display and method for controlling same with speech.
Invention is credited to Zwern, Arthur L..
Application Number | 20010035845 09/895576 |
Document ID | / |
Family ID | 24250862 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010035845 |
Kind Code |
A1 |
Zwern, Arthur L. |
November 1, 2001 |
Portable display and method for controlling same with speech
Abstract
A virtual computer monitor is described which enables
instantaneous and intuitive visual access to large amounts of
visual data by providing the user with a large display projected
virtually in front of the user. The user wears a head-mounted
display containing a head-tracker, which together allow the user to
position an instantaneous viewport provided by the head-mounted
display at any position within the large virtual display by turning
to look in the desired direction. The instantaneous viewport
further includes a mouse pointer, which may be positioned by
turning the user's head, and which may be further positioned using
a mouse or analogous control device. A particular advantage of the
virtual computer monitor is intuitive access to enlarged computer
output for visually-impaired individuals.
Inventors: |
Zwern, Arthur L.; (San Jose,
CA) |
Correspondence
Address: |
OPPENHEIMER WOLFF & DONNELLY LLP - SILICON VALLEY
1400 PAGE MILL ROAD
PALO ALTO
CA
94304
US
|
Family ID: |
24250862 |
Appl. No.: |
09/895576 |
Filed: |
June 28, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09895576 |
Jun 28, 2001 |
|
|
|
09373186 |
Aug 12, 1999 |
|
|
|
09373186 |
Aug 12, 1999 |
|
|
|
09235096 |
Jan 21, 1999 |
|
|
|
6127990 |
|
|
|
|
09235096 |
Jan 21, 1999 |
|
|
|
08563525 |
Nov 28, 1995 |
|
|
|
Current U.S.
Class: |
345/8 |
Current CPC
Class: |
G09B 21/008 20130101;
G09B 9/00 20130101 |
Class at
Publication: |
345/8 |
International
Class: |
G09G 005/00 |
Claims
What is claimed is:
1. A computer implemented method for assisting a user in the
control and operation of a display driven computer system, the
computer system being display driven in that a primary source of
feedback for interacting with the computer system is visual
feedback generated by the computer system, the visual feedback
intended for display upon any display screen coupled with the
computer system, the computer implemented method comprising the
acts of: equipping a user with a display device coupled to a
display driven computer system; mapping visual feedback generated
by the computer system into a virtual desktop suitable for display
via the display device; displaying a certain portion of the virtual
desktop via the display device; tracking movement of the display
device; updating the displayed certain portion of the virtual
desktop in response to the tracked movement of the display device;
monitoring audio input in order to recognize verbal user commands;
and controlling the computer system according to recognized verbal
user commands.
2. A computer implemented method as recited in claim 1, the
computer implemented method further comprising the acts of:
recognizing that a monitored verbal command corresponds to a
magnification factor selection; and updating the displayed certain
portion of the virtual desktop in a manner correlated to the
recognized magnification factor selection.
3. A computer implemented method as recited in claim 2, wherein the
recognized magnification factor selection is an absolute
magnification command.
4. A computer implemented method as recited in claim 2, wherein the
recognized magnification factor selection is a relative
magnification command.
5. A computer implemented method as recited in claim 1, the
computer implemented method further comprising the acts of:
recognizing that a monitored verbal command corresponds to a
position command; and updating the displayed certain portion of the
virtual desktop in a manner correlated to the recognized position
command.
6. A computer implemented method as recited in claim 5, wherein the
recognized position command corresponds to a "center me" command so
that the act of updating the displayed certain portion results in
centering the displayed certain portion within the virtual
desktop.
7. A computer implemented method as recited in claim 5, wherein the
recognized position command corresponds to a "top right" command so
that the act of updating the displayed certain portion results in
positioning the displayed certain portion within the top right of
the virtual desktop.
8. A computer implemented method as recited in claim 1, the
computer implemented method further comprising the acts of:
recognizing that the recognized verbal command corresponds to a
control tracking command; and controlling the display driven
computer system in a manner correlated to the recognized control
tracking command.
9. A computer implemented method as recited in claim 8, wherein the
recognized control tracking command is a "lock vertical" command
and the act of controlling the display driven computer system
includes a lock-out response to vertical tracking, whereby control
of horizontal movement is made simpler for the user.
10. A computer implemented method as recited in claim 1, wherein
the recognized verbal command corresponds to a switch system
operating mode command.
11. A computer implemented method as recited in claim 1, wherein
the recognized verbal command is an application specific
command.
12. A computer implemented method as recited in claim 1, wherein
the recognized verbal command corresponds to a "page down"
command.
13. A computer implemented method as recited in claim 1, wherein
the recognized verbal command corresponds to a "scroll text"
command.
14. A computer implemented method as recited in claim 1, wherein
the recognized verbal command corresponds to a font control
command.
15. A computer implemented method as recited in claim 1, wherein
the recognized verbal command corresponds to a text edit
command.
16. A computer implemented method as recited in claim 1, further
including the act of monitoring audio input in order to recognize
verbal user content.
17. A computer implemented method for assisting a user in the
control and operation of a display driven computer system, the
computer system being display driven in that a primary source of
feedback for interacting with the computer system is visual
feedback generated by the computer system, the visual feedback
intended for display upon any display screen coupled with the
computer system, the computer implemented method comprising the
acts of: equipping a user with a display device coupled to a
display driven computer system; mapping visual feedback generated
by the computer system into a virtual desktop suitable for display
via the display device; displaying a certain portion of the virtual
desktop via the display device; tracking movement of the display
device; updating the displayed certain portion of the virtual
desktop in response to the tracked movement of the display device;
monitoring audio input in order to recognize verbal user content;
and providing the display driven computer system content according
to recognized verbal user content.
18. A device for assisting a user in the control and operation of a
display driven computer system, the computer system being display
driven in that a primary source of feedback for interacting with
the computer system is visual feedback generated by the computer
system, the visual feedback intended for display upon a display
screen coupled with the computer system, comprising: a tracking
device for sensing motion of the display device, converting a
sensory input generated by said motion sensed into tracking data,
and inputting said tracking data into said computer; and an audio
input device for converting user audio data into a digital
format.
19. A device as recited in claim 18, wherein said tracking device
includes at least one gyroscope.
20. A device as recited in claim 18, wherein said tracking device
includes at least one accelerometer.
21. A device as recited in claim 18, wherein said audio input
device includes a microphone.
22. A device as recited in claim 18, wherein said audio input
device includes a voice recognizer.
23. A device as recited in claim 18, wherein said audio input
device is capable of distinguishing between audio commands and
audio content.
24. A device for assisting a user in the control and operation of a
display driven computer system, the computer system being display
driven in that a primary source of feedback for interacting with
the computer system is visual feedback generated by the computer
system, the visual feedback intended for display upon a display
screen coupled with the computer system, comprising: a tracking
device for sensing motion of the display device, converting a
sensory input generated by said motion sensed into tracking data,
and inputting said tracking data into said computer, said tracking
device including at least one accelerometer; and an audio input
device for converting user audio data into a digital format, said
audio input device including a voice recognizer operable to
distinguish between audio command and audio content.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of Co-Pending application Ser. No.
09/373,186 filed Aug. 12, 1999, which is incorporated herein by
reference, which is a continuation of Application No. 09/235,096
filed Jan. 12, 1999, now U.S. Pat. No. 6,127,990, also which is a
continuation of application Ser. No. 08/563,525 filed Nov. 28,
1995, now abandoned.
FIELD OF THE INVENTION
[0002] The invention relates to human/computer interfaces to visual
data and more particularly to systems that must display a larger
amount of visual data than may be conveniently displayed in a
single conventional computer monitor. The present invention uses
virtual reality techniques to provide instantaneous and intuitive
access to large fields of visual data, and to provide
visually-impaired users with enhanced access to enlarged visual
data.
DESCRIPTION OF PRIOR ART
[0003] Among the visually-impaired population, the most common
approach to computer access is specialized software and/or hardware
that enlarges the image displayed on the computer monitor. This is
because simpler solutions such as moving closer to the monitor,
using a larger monitor, adding an optical screen magnifier, or
using a spectacle-mounted telescopic system provide either limited
magnification or a very limited viewing field. Examples of
commercially-available screen enlargers include LP-DOS by Optelec
(Westford, Mass.), Zoomtext by Ai Squared (Manchester Center, Vt.),
MAGic by Microsystems Software (Framingham, Mass.), and Magnum by
Arctic Technologies (Troy, Mich.). In addition, simplistic screen
enlargement modules are included in both the Microsoft Windows and
Apple Macintosh operating systems.
[0004] These conventional computer display magnification solutions
operate by magnifying the original image of a software
application's output to a "virtual page" whose size is much larger
than the physical monitor. For example, with a magnification of 10,
a standard 8.5".times.11" page would be approximately 7 feet wide
by 9 feet tall. The visually-impaired user then operates the
computer by using a mouse, joystick, or cursor keys to control
which portion of the virtual page is shown on the monitor at any
given point in time. Since the monitor is fixed, the user is in
essence moving the virtual page across the monitor, in a manner
analogous to that used in closed-circuit television (CCTV) systems
for magnifying book pages.
[0005] In most cases, conventional screen magnification is
performed completely in software running on the host computer's
central processing unit (CPU). While this provides a very low-cost
solution, the data to be shown on the display must be rendered in
its entirety whenever the user pans to a new location within the
enlarged image. This can result in lags between commanding the
computer to pan and seeing the new image. To overcome this problem,
the entire virtual image can be rendered and stored in a video
display buffer. Then, as the user selects a portion of the image
for viewing, the required portion of the data can be quickly read
out of the display buffer and sent to the display device. An
example of such a hardware-accelerated screen magnifier is the
Vista by Telesensory, Inc. (Mountain View, Calif.). This technique
is a form of hardware acceleration known as image deflection.
[0006] Unfortunately, there are two basic shortcomings to the
conventional approach, even with hardware acceleration. The first
problem is spatial orientation, in that it is difficult to
determine where on the page one's view is directed at any given
time. This occurs because the monitor does not move, and there are
no other visual cues to indicate where on the virtual page one's
line of sight is facing. This spatial orientation problem is
exacerbated for high magnifications and for portable systems
employing small display monitors. For example, one study (Goodrich,
et. al.) found mean magnifications of 15.48.times. for nearly 100
experienced users of closed-circuit television devices. At
15.times., a 15" monitor can only display about 1% of a standard
8.5".times.11" page, making most computer work essentially
impossible for such users. The problem is further exacerbated by
the emergence of graphically-intensive computing regimes such as
Microsoft Windows and the Internet World Wide Web, where individual
graphic elements may be magnified to become larger than an
instantaneous viewing window, or may be automatically generated
outside of the user's instantaneous viewing window without the
user's awareness.
[0007] The second fundamental problem in the conventional approach
is dynamic control, in that all of the various control schemes for
navigating about the page are cumbersome, confusing, and slow. This
is because the navigation methods are unintuitive, relying on such
logic as "use joystick to move cursor around screen, and when
cursor reaches the edge of the screen, the next portion of document
in that direction will be displayed." Alternatively, some screen
enlargers maintain the cursor at the center of the screen, and
require the user to position a desired insertion point over the
cursor by moving the entire virtual page with a mouse or joystick.
In all cases, dynamic control is not only unintuitive, but requires
use of at least one hand, which negatively impacts productivity,
and may make use by physically-impaired users difficult or
impossible.
[0008] Together, these spatial orientation and dynamic control
problems were termed the "field navigation" problem in the National
Advisory Eye Council's 1994-98 National Plan (Legge, et. al.), in
which the Low Vision and its Rehabilitation Panel identified this
area as a particularly promising opportunity for new
technologies.
[0009] One promising new technology that is now maturing is virtual
reality, which is typically defined as a computer-generated
three-dimensional environment providing the ability to navigate
about the environment, turn one's head to look around the
environment, and interact with simulated objects in the environment
using a control peripheral.
[0010] In a virtual reality system, the user is "immersed" in a
synthetic environment, in which virtual objects can be located
anywhere in the user's physical space. The user views these objects
by wearing a head-mounted display (HMD), which uses an optical
system to cause a tiny display source such as a cathode ray tube or
liquid crystal display to appear as a large display screen several
feet in front of the user. Since the display source (or sources in
the case of two eyes) is fixed to the user's head, the display is
viewable regardless of where the user points his line-of-sight. The
user also wears a head-tracker, which senses the direction the user
is facing, and sends this information to the host computer. The
computer uses this data to generate graphics corresponding to the
user's line of sight in the virtual environment. This approach to
human/computer interfaces was first conceived by Ivan Sutherland in
1966 for use in military simulators, and was first commercialized
in the form of the Eyephone head-mounted display by VPL Research in
the late 1980s.
[0011] Prior art in this area includes a wide range of relevant
patents describing low-vision aids, improved virtual reality
systems and components such as HMDs and head-trackers, but none
which embody or anticipate the present invention.
[0012] In the field of low-vision aids, U.S. Pat. No. 4,227,209
issued Oct. 10, 1980 discloses an electronic sensory aid for
visually-impaired users including an image sensor and a display
array, wherein the degree of magnification provided in the display
array may be adjusted by changing the number of display elements
corresponding to each sensor array element. For use in electronic
sensory aid applications requiring a large depth of focus, an
improved image capture approach is disclosed in U.S. Pat. No.
5,325,123 issued Jun. 28, 1994, in which the imaging camera
includes an opaque stop with a small aperture, thus allowing the
magnification to be adjusted by moving the camera towards or away
from the object to be magnified. A non-electronic sensory aid is
disclosed in U.S. Pat. No. 4,548,485 issued Oct. 22, 1985, in which
an XY stage is used to move textual material across an optical
viewing system that captures a portion of the textual material for
enlargement.
[0013] In U.S. Pat. No. 5,125,046 issued Jun. 23, 1992, and U.S.
Pat. No. 5,267,331 issued Nov. 30, 1993, an improved imaging
enhancer for visually-impaired users is disclosed in which an image
is captured, digitized, and electronically enhanced to increase
contrast before displaying the imagery. An improvement to this
approach using a head-mounted display is disclosed in U.S. Pat. No.
5,359,675, issued Oct. 25, 1994.
[0014] In the field of virtual reality systems, U.S. Pat. No.
5,367,614 issued Nov. 22, 1994 to Bisey discloses a
three-dimensional computer image display system using an ultrasonic
transceiver head-tracking system to control a three-dimensional
display to cause the image to change its perspective in response to
head movements. In addition, U.S. Pat. No. 5,442,734 issued Aug.
15, 1995 to Murakami discloses a virtual reality system
incorporating a head-mounted display, head-tracker, and image
processing system in which predictive tracking algorithms are used
to differentially update portions of the display field to provide
more rapid updating of those portions of the display field
corresponding to the center of the user's visual field. In U.S Pat.
application Ser. No. 07/621,446 (pending) filed by VPL Research,
Inc., a virtual reality system is disclosed in which spatialized
audio cues are generated to provide real-time feedback to users
upon successful completion of manual tasks such as grasping virtual
objects using a sensor-laden glove input device.
[0015] In the head-mounted display field, U.S. Pat. No. 5,003,300
issued Mar. 26, 1991 to Wells discloses a raster-based head-mounted
display that may be used to display an image to either eye. U.S
Pat. No. 5,151,722 issued Sep. 29, 1992 to Massof discloses a
video-based head-mounted display featuring a unique folding optic
configuration so that the device may be worn like a pair of
glasses. U.S. Pat. No. 5,281,957 issued Jan. 25, 1994 to Schoolman
discloses a portable computer system incorporating a head-mounted
display that may be hinge-mounted to an eyeglass frame so that the
display may be folded up out of the way for viewing the physical
environment. A wide variety of additional patents in the area of
specific design improvements for head-mounted display devices
exists, however, the specific head-mounted display design approach
employed to effect the present invention is not critical, so long
as image quality, brightness, contrast, and comfort are maintained
at high levels.
[0016] In recent years, there have been several attempts made to
apply head-mounted displays to the problems of enhancing imagery
for visually-impaired users. One such effort has resulted in the
Low-Vision Enhancement System (LVES) developed by Johns Hopkins
University and marketed commercially by Visionics (Minneapolis,
Minn.). The LVES device incorporates a head-mounted display with
integrated cameras and an image processing system. The cameras
generate an image of whatever is positioned directly in front of
the user, and the image processing system enlarges the image and
performs enhancement functions such as contrast enhancement. While
the LVES device can provide magnified imagery of real-world objects
to some visually-impaired users, it suffers from several
shortcomings compared to the present invention. First, the LVES
does not incorporate a head-tracker to provide a hands-free means
for navigating within computer data. Further, the LVES suffers from
a jitter problem exactly analogous to that experienced by users of
binoculars or telescopes. In simple terms, any jitter in the user's
line-of-sight is magnified by the same factor as the imagery, which
causes the image provided to the user to appear unsteady.
[0017] U.S. Pat. No. 5,109,282 issued Apr. 28, 1992 to Peli
discloses a novel image processing method for converting continuous
grey tone images into high resolution halftone images, and
describes an embodiment of the method applicable to presentation of
enlarged imagery to visually-impaired users via a head-mounted
display. In this device, the imagery is generated by a conventional
camera manually scanned across printed text as is common in
closed-circuit television systems for the visually-impaired. The
head-mounted display is a Private Eye by Reflection Technologies
(Waltham, Mass.), which employs a linear array of light-emitting
diodes converted to the impression of a rectangular array by means
of a scanning mirror. In the disclosed device, benefits of using a
head-mounted display for low-vision access to printed material in
portable situations are discussed, including the larger visual
field, higher visual contrast, lighter weight, and smaller physical
size provided by an HMD compared to a portable conventional
television monitor. However, no connection to a computer for
viewing computer-generated imagery is disclosed or anticipated, and
no incorporation of a head-tracking device is disclosed or
anticipated.
[0018] In the tracker art, a variety of tracking approaches and
applications have been conceived and constructed. U.S. Pat. No.
5,373,857 issued Dec. 12, 1994 to Travers, discloses a
head-tracking approach for the yaw degree of freedom in virtual
reality applications consisting of a magnetic sensor disposed on a
headset to produce a displacement signal relative to angular
displacement of the head set with respect to the earth's magnetic
field. A more sophisticated approach has been developed by the
Massachusetts Institute of Technology (MIT), in which an analogous
magnetic sensor is used to correct drift in a much faster
differential sensor such as an accelerometer, which sensors
together provide extremely rapid response and high accuracy within
a single package. The MIT approach, believed to be patent-pending,
additionally incorporates differential sensors to detect changes in
the pitch and roll degrees of freedom, which sensors may also be
corrected using slower absolute sensors such as liquid-filled
capacitive tilt sensors.
[0019] Also within the tracker art, a number of devices have been
disclosed which sense head movement for purposes of controlling
positioning of a cursor or mouse pointer within the viewable
portion of a conventional display monitor. U.S. Pat. No. 4,209,255
issued Jun. 24, 1980 to Heynau discloses a system for pilots
employing a light-emitting diode mounted on the pilot's head, with
photodiodes located on the display to sense the tapered energy
field from the light-emitting diode for purposes of determining the
pilot's aimpoint within the display.
[0020] U.S. Pat. No. 4,565,999 issued Jan. 21, 1986 to King
discloses a cursor control system for use with a data terminal
wherein a radiation source and a radiation sensor are used to
determine changes in a user's head position for purposes of
controlling cursor position on the screen.
[0021] U.S. Pat. No. 4,567,479 issued Jan. 28, 1986 to Boyd
discloses a directional controller for video or computer input by
physically-impaired users consisting of a series of mercury
switches disposed in proximity to a user's head, wherein movements
of the user's head are sensed and converted into cursor control
commands. This device also employs a pressure switch activated by
the user's mouth which can provide a further control signal such as
that generated by clicking a mouse button.
[0022] U.S. Pat. No. 4,682,159 issued Jul. 27, 1987 to Davison
discloses an apparatus and method for controlling a cursor on a
computer display that consists of a headset worn by the user, and a
stationary ultrasonic transmitter for emitting sound waves which
are picked up by receivers in the headset. These sound waves are
compared for phase changes, which are converted into positional
change data for controlling the cursor.
[0023] U.S. Pat. No. 5,367,315 issued Nov. 22, 1994 to Pan
discloses an infrared-light based system that indicates head and
eye position in real time, so as to enable a computer user to
control cursor movement on a display by moving his or her eyes or
head. The device is intended to emulate a standard mouse, thereby
allowing use of the presently available software and hardware.
[0024] While the above examples demonstrate a well-developed art
for controlling computer cursors via head movement, none disclose
or anticipate application of head-controlled cursor movement within
a head-mounted display, and none anticipate an approach such as the
present invention wherein the cursor remains fixed at a particular
position within the display while the displayed data is moved
instead of the cursor. Movement of displayed data within a
head-mounted display in response to head movement has heretofore
been used only within virtual reality systems designed for
simulating sensory immersion within three-dimensional computer
simulations. In such applications, cursors or mouse pointers are
not controlled by head movement, but are generated when required
through the use of a separate hand-controlled input device.
[0025] While virtual reality is still a developmental technology
involving exotic graphics hardware, specialized software, and long
integration cycles, the concept of closing a control loop between
head-tracker data and HMD imagery can be implemented analogously
for viewing arbitrary computer data instead of
specially-constructed virtual environments. For normally sighted
individuals, this could be beneficial by providing a large virtual
computer desktop surrounding the user, which can provide
simultaneous access to a larger amount of visual data than is
possible using the small virtual desktops currently provided on
common computing platforms such as Macintosh and Windows. For
visually-impaired individuals, head-tracked HMD display techniques
can be used to conveniently access a magnified virtual page, and
thus enable productive computer use by nearly 1,000,000 new
users.
SUMMARY OF THE INVENTION
[0026] It is therefore an object of the current invention to solve
the field navigation problem by combining virtual reality display
techniques originally developed for military flight simulators with
screen magnification techniques, in order to create a novel and
intuitive display interface for visually impaired users.
[0027] It is another object of the current invention to provide an
intuitive computer display interface allowing the user to
automatically achieve proper spatial orientation by directly
coupling the user's head orientation to the displayed portion of a
magnified virtual page.
[0028] It is a further object of the current invention to provide
an intuitive portable computer display interface allowing the user
to automatically control the position of a cursor or mouse pointer
on a computer-generated virtual page by directly coupling the
user's head movements to movements of a cursor across the virtual
page, thus freeing the user's hands for other tasks.
[0029] It is an additional object of the present invention to
provide hands-free instantaneous selection from between many
concurrently active computer applications by changing one's
line-of-sight from one application window's virtual location to
another.
[0030] It is yet another object of the present invention to provide
and maintain a cursor at a user-selectable position within the
user's field-of-view, in order to support use of the virtual
computer display by users with arbitrary, non-central preferred
retinal loci.
[0031] It is still another object of the present invention to alert
the user to events occurring outside of the user's instantaneous
field-of-view through the use of spatialized audio alerts perceived
to originate from the direction of the event, thus causing the user
to turn and look in the direction of the event.
[0032] It is yet a further object of the present invention to
provide effective operation at magnifications much greater than
those possible using fixed monitors, by using a novel technique
known as spatial compression.
[0033] It is still another object of the present invention to
provide improved scrolling of imagery across the user's
field-of-view, through application of smoothing, thresholding,
prediction, and drift compensation algorithms to improve response
to raw data representing the user's instantaneous line of
sight.
[0034] It is still a further object of the present invention to
provide a computer display for visually-impaired users that is
convenient, lightweight, low-cost, minimally power hungry, and
capable of portable operation without degraded performance.
[0035] It is another object of the present invention to provide a
means for visually-impaired users to view enlarged video imagery in
real time over an expanded field-of-regard, thus reducing jitter
compared to head-mounted closed-circuit television systems.
[0036] In accordance with the present invention, there has been
devised a "virtual computer monitor" (VCM) which is broadly
comprised of a head-mounted display means worn by the user, a
head-orientation sensing means worn by the user, and software means
for interfacing these devices to a host computer such that the
user's head orientation data is processed to determine which
portion of an arbitrary software application's output imagery to
display. By properly matching the angle of head rotation to the
extent of scrolling across the magnified image, the image can be
made to appear fixed in space. The particular location of the
portion of the virtual image which is actually being seen by the
user is dependent upon the direction in which the user looks. As
the user looks to the right, the portion of the virtual image being
seen by the user is to the right of the portion of the virtual
image previously being seen by the user. Similarly, as the user
looks up, the portion of the virtual image being seen by the user
is above the portion of the virtual image previously seen by the
user. Upon initialization of the VCM device, the user triggers
calibration between the user's straight-ahead line of sight and the
center of the virtual page. From then on, the user can rotate her
head left, right, up, and down to visually scan across the page in
corresponding directions. The overall impression is analogous to a
normally sighted person scanning across a newspaper page.
[0037] As applied to a computer interface device for the
visually-impaired, the VCM software provides a magnification
adjustment to allow each user to achieve adequate visual resolution
without needlessly reducing his instantaneous viewing field. The
software also provides a cursor, which nominally remains positioned
at the center of the HMD physical field regardless of head
movements so that the cursor can be positioned anywhere upon the
virtual page by turning to face that location. A further adjustment
allows setting the fixed cursor location to any arbitrary position
in the HMD device's physical field, so that users with unusable
portions of their visual fields can select an alternative preferred
retinal loci instead of the center. A software selection also
provides an overview display, which shows a reduced-magnification
image of the entire virtual page, with a bold black box
highlighting the outline of the instantaneous field within the
entire field.
[0038] An additional important feature is the ability to
temporarily adjust the cursor position in real-time using a
controller peripheral such as a joystick or mouse. This feature
allows fine positioning of the cursor within the field by
temporarily locking the head-tracking system to freeze a portion of
the virtual page on the physical display, while the controller is
used to move the cursor in small increments.
[0039] An additional important feature is the ability to display
image components in addition to the cursor at fixed points in the
physical display, which allows menus or other icons to remain in
the user's instantaneous viewing field at all times while scrolling
across image content.
[0040] An additional important feature resides in the ability to
reduce the lag between a head motion and display of the new
direction's image by using image deflection, thresholding,
smoothing, prediction, and a novel drift compensation technique to
reduce display "swimming", which is caused whenever imperfect head
orientation sensing causes the displayed image to not appear fixed
in real-space.
[0041] An additional important feature resides in the ability to
magnify images by extremely large factors using spatial field
compression, where the displayed image is scrolled across the
physical display at a faster rate than the head is turned. This
enables use by individuals with limited head motion, and allows
magnification to levels that would otherwise require turning
completely around to view edges of the image.
[0042] An additional important feature resides in the use of a
partially immersive HMD, which avoids simulation sickness by
allowing the user to maintain a constant frame of reference in the
physical world since real objects can be seen around one or more
edges of the display.
[0043] It is therefore an advantage of the current invention that
it solves the field navigation problem by combining virtual reality
display techniques originally developed for military flight
simulators with screen magnification techniques, in order to
provide a novel and intuitive display interface for visually
impaired users.
[0044] It is another advantage of the current invention that it
provides an intuitive computer display interface allowing the user
to automatically achieve proper spatial orientation by directly
coupling the user's head orientation to the displayed portion of a
magnified virtual page.
[0045] It is a further advantage of the current invention that it
provides an intuitive computer display interface allowing the user
to automatically control the position of a cursor or mouse pointer
on a computer-generated virtual page by directly coupling the
user's head movements to movements of a cursor across the virtual
page, thus freeing the user's hands for other tasks.
[0046] It is an additional advantage of the present invention that
it provides hands-free instantaneous selection from between many
concurrently active computer applications by changing one's
line-of-sight from one application window's virtual location to
another.
[0047] It is yet another advantage of the present invention that it
provides and maintains a cursor at a user-selectable position
within the user's field-of-view, in order to support use of the
virtual computer display by users with arbitrary, non-central
preferred retinal loci.
[0048] It is still another advantage of the present invention that
it alerts the user to events occurring outside of the user's
instantaneous field-of-view through the use of spatialized audio
alerts perceived to originate from the direction of the event, thus
causing the user to turn and look in the direction of the
event.
[0049] It is yet a further advantage of the present invention that
it provides effective operation at magnifications much greater than
those possible using fixed monitors, by using a novel technique
known as spatial compression.
[0050] It is still another advantage of the present invention that
it provides improved scrolling of imagery across the user's
field-of-view, through application of smoothing, thresholding,
prediction, and drift compensation algorithms to improve response
to raw data representing the user's instantaneous line of
sight.
[0051] It is still a further advantage of the present invention
that it provides a computer display for visually-impaired users
that is convenient, lightweight, low-cost, minimally power hungry,
and capable of portable operation without degraded performance.
[0052] It is another advantage of the present invention that it
provides a means for visually-impaired users to view enlarged video
imagery in real time over an expanded field-of-regard, thus
reducing jitter compared to head-mounted closed-circuit television
systems.
[0053] The above and other objects, features, and advantages of the
present invention will become more readily understood and
appreciated from a consideration of the following detailed
description of the preferred embodiment when taken together with
the accompanying drawings, which, however, should not be taken as
limitative to the present invention but for elucidation and
explanation only.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] FIG. 1 is a conceptual sketch illustrating operation of a
conventional screen enlarger.
[0055] FIG. 2 is a block diagram of the hardware components of the
virtual computer monitor.
[0056] FIG. 3 is a conceptual sketch illustrating operation of a
virtual computer monitor, and intuitive field navigation via head
rotation.
[0057] FIG. 4 illustrates various means for configuring the virtual
computer monitor display, including A) typical configuration, B)
typical configuration in combination with a blockage of the user's
foveal vision, C) mouse pointer/cursor offset to a non-central
preferred retinal locus, and D) Entire display field offset to be
centered about a non-central preferred retinal locus.
[0058] FIG. 5 is a block diagram of the logical flow of data
processing in an advanced embodiment of the virtual computer
monitor.
[0059] FIG. 6 is a further embodiment of the present invention
applied to magnification of real-time imagery.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0060] The system of this invention concerns a computer 12
controlled by a user through conventional means such as a keyboard
14 and input controller 16, and whose output is viewed on a display
monitor 18. Referring to FIG. 1, the invention is specifically
intended for use in applications where the total amount of data to
be viewed can be configured as a virtual display 20, which is
significantly greater in extent than the amount of data that can be
conveniently viewed within an instantaneous viewport 22 provided by
the display monitor 18. An example of such an application is when
the virtual display 20 consists of a large computer desktop running
several application windows, while the amount of data that can be
visually resolved within the instantaneous viewport 22 consists of
a single application window. Another example of such an application
is when the virtual display 20 consists of a word-processing
document magnified for a visually-impaired user by a screen
enlarger 24, which may consist of software or a combination of
software and hardware. In either case, conventional control means
such as a keyboard 14 or input controller 16 may be used to select
which portion of the virtual display 20 is shown within the display
monitor 18 at any given moment, as described in the prior art.
[0061] Referring to FIG. 2, the most basic embodiment of the
invention is achieved by implementing the display monitor as a
head-mounted display 26, wherein tiny display sources such as LCDs
are held within close proximity to the user's eyes, and optically
coupled to the eyes with a lensing system such that the image of
the computer display appears to float in space several feet in
front of the user. Such devices are well known in the art, and are
commercially available from sources including General Reality
Company (San Jose, Calif.), Optics 1 (Westlake, Calif.), and
Virtual I/O (Seattle, Wash.). In addition to the head-mounted
display, the user wears a head-tracker 28, which senses changes in
orientation of the user's head and reports them to the portable
computer 12 to result in the perception of scrolling the
instantaneous viewport 22 across the virtual display 20.
Head-trackers are also well-known in the art, and a variety of
different devices are available from sources including General
Reality Company, Precision Navigation (Mountain View, Calif.), and
Polhemus Inc. (Colchester, Vt.).
[0062] With respect to the present invention, a wide variety of
different head-mounted displays 26 and head-trackers 28 may be used
without affecting the fundamental operating concepts embodied
therein, and many suitable devices are commercially available. For
the head-mounted display 26, it is important to provide adequate
field-of-view to ensure that a significant portion of the user's
visual field is addressed, and to provide a sufficient number of
picture elements, or pixels, so that small text can be resolved.
Useful minimums are twenty degree field-of-view and 100,000 pixels
per eye, although these figures are subjective. In addition, visual
contrast must be high (100 to 1 or greater) for visually-impaired
users. For some visually-impaired users, maximizing contrast can
become sufficiently critical that a color display can not be used,
and a black and white unit must be used instead. In general,
parameters such as field-of-view, pixel count, contrast,
size/weight, cost, and other factors such as apparent image
distance well-known in the art of head-mounted display design may
be traded-off to provide a best compromise over a varied population
of users, or may be traded-off to optimize performance for a single
user.
[0063] The simplest embodiment of the invention uses a
CyberTrack.TM. model head-tracker 28 from General Reality Company.
This model provides an output signal emulating that of a mouse,
which can be read directly by a standard Microsoft mouse driver 30
for purposes of controlling the manner in which the instantaneous
viewport 22 is selected from within the virtual display 20. In
alternative embodiments using a different head-tracker 28 which can
not so emulate a mouse, an additional software module can be used
to interpret the output of the head-tracker 28 and convert the
output into "mickeys" that emulate mouse output, or an additional
software module can adapt the output of the head-tracker 28 for
directly controlling scrolling of the instantaneous viewport 22
without use of an intervening mouse driver. All told, a wide
variety of alternative means for converting head-tracker output
into scrolling of the instantaneous viewport have been conceived,
so the approach selected for the present embodiments should not be
considered limitative of the invention.
[0064] The portable computer 12, includes a keyboard 14 and a mouse
16. In this embodiment, software on the portable computer 12
includes screen enlarger software 24 and a Microsoft(.RTM.) mouse
driver. An instantaneous viewport provided by the display 26 gives
the user the perception that a virtual display is fixed in front of
the user. The user may transport the display 26, the head tracker
28 and the portable computer 12 wherever the user wishes to use the
device of the present invention.
[0065] Referring to FIG. 3, the result of the invention is to
provide the user with the perception that the virtual display 20 is
fixed in space in front of the user, and that the user can position
the instantaneous viewport 22 provided by the head-mounted display
26 at any point within the virtual display 20 merely by rotating
his or her head to look in the desired direction. Because the
user's nervous system provides proprioceptive feedback which
constantly provides the user with a sense of direction, and because
turning to look in a particular direction is a natural and
intuitive means for viewing objects in that direction, the
invention provides a solution for both the spatial orientation and
dynamic control aspects of the field navigation problem.
[0066] Referring to FIG. 4, further detail of the instantaneous
viewport is shown. Specifically, a mouse pointer 32 is shown. The
mouse pointer 32 is typically maintained in the center of the
instantaneous viewport 22 as the viewport is scrolled, and is used
to allow selection of particular data items by the user. Such
selection may be performed by clicking a button on the input
controller 16. In the present invention, the mouse pointer may also
be adjusted to remain at a non-central position 34 within the
instantaneous viewport 22 while the viewport is scrolled. Such a
non-central position 34 may be used in a case where the user
suffers from a visual impairment such as macular degeneration,
which can cause the foveal (central) portion of the user's visual
field to be blocked, as illustrated by the visual blockage 36. An
alternative approach in the event of a visual blockage is to
physically rotate the head-mounted display 26 with respect to the
user's line-of-sight, so that the instantaneous viewport 22 is no
longer centered around the user's line-of-sight, but is instead
skewed into an offset position 38.
[0067] In any of these embodiments, an improvement to the simple
scrolling of the instantaneous viewport 22 can be achieved using
hardware or software logic that enables scrolling using a
combination of data generated by the head-tracker 28 and the input
controller 16. Specifically, when the mouse is not active,
head-tracker 28 output is used to perform large-magnitude
positioning of the instantaneous viewport 22 with respect to the
virtual display 20. Once the instantaneous viewport 22 is
positioned at the approximate desired position using head
movements, the input controller 16 can then be used to perform fine
positioning of the instantaneous viewport. The input controller 16
can also be used to select data items, or click and drag to select
multiple data items, as is common within the art. Whenever such
actions are taken with the mouse, the instantaneous viewport is
moved appropriately, maintaining the mouse pointer 32 at its
selected location within the instantaneous viewport. In a preferred
embodiment, the input controller 16 and head-tracker 28 can operate
simultaneously, which allows "click & drag" functions such as
holding down the mouse button to anchor one comer of a selection
box, then scrolling the head until an opposing comer is reached,
and releasing the mouse button to select all of the items within
the resulting selection box.
[0068] The present invention has been implemented in two
alternative prototype embodiments, with additional embodiments
contemplated. The first embodiment is constructed using an Apple
Macintosh Duo 230 portable computer 12, a General Reality CyberEye
Model 100 head-mounted display 26, and InLARGE screen magnifier
software by Berkeley Systems (Berkeley, Calif.). In this
embodiment, the head-tracker 28 is an experimental device utilizing
Gyrostar ENC-05E solid-state gyroscopes by Murata Manufacturing
Company (Kyoto, Japan, and US location at Smyrna, Ga.). Two
gyroscopes are used, one each for the head's pitch (elevation) and
yaw (direction) degrees of freedom. The output of each gyroscope
consists of a differential voltage, with the difference voltage
directly proportional to the angular velocity of the sensor. These
outputs are fed to the Macintosh computer 12 via the Apple Desktop
Bus (ADB) Port, which is used on all Macintosh computers for
accepting input from keyboards, mice, and other input control
devices. Because the gyroscopes output differential data
representing an angular velocity, the data is digitized using a
simple analog-to-digital converter integrated circuit, and then
used directly for scrolling the imagery, with only a linear scaling
factor applied. This scaling factor is dependent on the
magnification factor applied to the imagery, and serves to maintain
the enlarged image at a fixed position in space as perceived by the
user. In the case of an absolute orientation tracker such as a
magnetometer, the data must first be converted from orientation to
rate of change in orientation by taking the mathematical derivative
of the data with respect to time.
[0069] In this first embodiment and most conceivable alternative
embodiments which utilize differential head tracking devices such
as gyroscopes and accelerometers, various tracking errors are
introduced by the lack of a stable reference. These errors include
drift, temperature instability, hysteresis, cross-axis coupling,
and limited dynamic range.
[0070] Drift is evidenced by slow motions in the imagery which
occur in the absence of any true head motion, and is corrected by
incorporating a low-frequency cut-off filter in the tracking data
output. Such low-frequency cut-off filters are well-known in the
tracking art, and do not affect perceived performance.
[0071] Temperature instability is evidenced by drift that occurs
following rapid changes in the ambient temperature in which the
tracker is used. Some such instability is removed with software
which acts like a low-frequency cut-off filter by ignoring D.C.
drift, while some is unavoidable and requires a waiting period for
temperature of the system hardware to stabilize. This software
ignores any D.C. signal component from the head tracker 28 and
allows a scaling factor to be input to the system to control the
magnitude of the shift in the virtual image as a function of the
amount of rotation of the user's head.
[0072] Hysteresis is evidenced by sensitivity differences between
motion in one direction and motion in a direction 180 degrees
opposite. This artifact can be addressed by using a different
scaling factor depending upon the tracker's direction of travel.
The magnitude of this sealing factor can be determined
experimentally, depending upon the magnitude and direction of the
hysteresis.
[0073] Cross-axis coupling is evidenced by the displayed image
moving a small amount in one axis when all of the head motion is
along an orthogonal axis. This artifact is also controlled by the
software which acts like a low-frequency cut-off filter, and may be
further controlled by disabling one axis whenever the orthogonal
axis rate of motion is greater than an empirically-determined
threshold.
[0074] Finally, dynamic range limitations result in upper and lower
limits to the rate at which the head may be turned while still
maintaining the perception that the image is fixed in space. The
lower limit is nominally determined by the electronic noise floor
of the sensor devices, although it is raised by addition of the
low-frequency cut-off filter. The upper limit is determined by the
maximum rate of change measurable by the sensor. If this rate of
change is exceeded by overly rapid turning of the user's head, the
imagery will appear to move in the same direction as the head is
turning. This last artifact has not been solved, but may be
addressed in a future embodiment through the use of an absolute
position tracker.
[0075] In this first embodiment, the Apple Macintosh ADB port
allows simultaneous operation of multiple input control
peripherals. Because of this feature, either the input controller
16 or a variety of secondary controllers may be used in conjunction
with the head-tracker 28 to perform navigation within the imagery.
Such controllers include joysticks, trackballs, light pens, simple
switches, or any other control device which is ADB port
compatible.
[0076] The second embodiment of the invention has been implemented
for the Intel/Microsoft personal computer architecture. In this
embodiment, the computer 12 is a 90 Mhz Pentium host computer, the
head-mounted display 26 is a CyberEye Model 100, and the
head-tracker 28 is a 3-axis magnetometer, available as the Model
TCM-2 from Precision Navigation, Inc. (Mountain View, Calif.) or
the CyberTrack.TM. from General Reality Company (San Jose, Calif.).
This embodiment has been made functional using LP-DOS from Optelec
(Westford, Mass.) as the screen enlarger 24, although alternative
commercially available screen enlargers may be used without
modifying the remaining components of the system.
[0077] In this second embodiment, the selected head-tracker 28 is
an absolute orientation sensor, although any alternative
head-tracking device may be used. The specific 3-axis magnetometer
used as the head-tracker 28 in this embodiment connects to the
serial port of the computer 12, and provides an internal conversion
from absolute position to differential data in the form of mouse
"mickeys" compatible with the Intel/Microsoft personal computer
architecture. Because of this feature, the output of the
head-tracker 28 can be read directly by a standard Microsoft mouse
driver, which provides a menu for setting the scaling factor
required for maintaining a fixed image as perceived by the
user.
[0078] In this second embodiment, the Intel/Microsoft personal
computer architecture does not make use of the Apple ADB bus, but
instead uses RS-232 serial communication ports to connect to
control devices such as the head-tracker 28 and the input
controller 16. This complicates the system design because the
standard Microsoft mouse driver can only access one serial port
(and therefore one control device) at any particular moment. Since
proper operation of the invention requires simultaneous response to
the head-tracker 28 and the input controller 16, hardware or
software is required to access two control devices
simultaneously.
[0079] In the most common case of a conventional computer mouse
employed as the input controller 16, this may be accomplished in
one of at least five ways. First, an existing mouse driver that
includes dual-port capability such as the original Borland mouse
driver may be used. Second, the source code for the standard
Microsoft mouse driver may be modified to support simultaneous
access to two serial ports. Third, a device such as the "WhyMouse"
by P. I. Engineering (Williamston, Mich.) may be used. This device
serves as a "Y" adapter to connect two mouse-type pointing devices
into one serial port. Circuitry internal to the WhyMouse
automatically routes one or the other device's data to the serial
port based on a priority scheme, wherein the first device to emit
data gains control of the input. Fourth, a custom solution can be
implemented in the form of a unique software driver, or fifth, in
the form of a software module running on an intelligent
input/output controller such as the Rocketport32 card from
Industrial Computer Source (San Diego, Calif.). Such intelligent
input/output controllers are available from several commercial
sources in the form of a circuit board that may be inserted in an
expansion slot within the computer 12. These circuit boards include
two or more serial ports, as well as an on-board processor that can
manipulate the inputs from the serial ports prior to delivering the
tracking data to the computer's internal bus.
[0080] Of the four potential approaches to dual input device
operation, the preferred embodiment exploits the fourth approach.
This is because a custom software module avoids hardware costs,
while providing the greatest flexibility in terms of application
optimization and user convenience. For example, a custom software
module allows the user to select whether the input controller 16
and head-tracker 28 can operate simultaneously in the manner
preferred by the inventor, or whether the input controller 16 and
head-tracker 28 operate in a priority scheme as provided in the
WhyMouse product. In addition, a custom software approach can
provide optional use of a variety of alternative devices as the
input controller 16. For example, some users may prefer a
hand-operated joystick to a mouse, while physically-impaired users
may require a finger-operated joystick or head-operated directional
switches with a puff & suck switch for activating the mouse
clicking function.
[0081] Referring to FIG. 5, a block diagram of an advanced
embodiment of the invention is shown. In FIG. 5, the computer 12,
keyboard 14, input controller 16, screen enlarger 24, head-mounted
display 26, and head-tracker 28 are illustrated as previously
defined, while a standard computer operating system such as
Microsoft Windows is conceptually shown as 42, a typical computer
application such as Microsoft Word is shown as 44, and a typical
display driver such as a VGA graphics board is shown as 46. The
software module used for combining the inputs of the input
controller 16 and head-tracker 28 is shown as the control driver
48. An additional software module called the input remapper 50 is
also shown interposed between the input controller 16 and the
control driver 48. This input remapper 50 is a program that
converts inputs from a variety of potential devices that may be
used as the input controller 16 into a single convenient data
format such as mouse mickeys. For example, the output of a joystick
used as the input controller 16 can be remapped by the input
remapper 50 so that pressing the joystick trigger button results in
a mouse click signal being sent to the control driver 48, moving
the joystick to the left results in emulation of sliding the mouse
to the left, etc. By separating the input control software into a
control driver 48 and an input remapper 50, the control driver 48
can be made standard, with only the input remapper 50 modified
whenever it is desirable to support a new type of input controller
16 within the invention. The use of an input remapper 50 is a
common approach in CD-ROM personal computer games, where the user
can select between the mouse, joystick, keyboard, or other devices
for purposes of controlling game play.
[0082] FIG. 5 also illustrates use of a tracking formatter 52,
which is a software module interposed between the head-tracker 28
and the control driver 48. The tracking formatter 52 performs
various functions depending upon the particular sensing means
employed within the head-tracker 28. These functions can be
separated into three categories.
[0083] The first category of functions performed by the tracking
formatter 52 is conversion of the data stream emanating from the
head-tracker 28 into a format readable by the control driver 48.
This conversion is tracking sensor-dependent. In the case of a
magnetometer-based tracker with mouse emulation as used in the
Intel/Microsoft embodiment, no conversion is required. In the case
of a magnetometer without mouse emulation, the tracking output
would consist of rapidly-updated azimuth and elevation position
figures, in which event the tracking formatter 52 would subtract
the prior position sample from the present sample and then convert
the format to mouse mickeys to provide the control driver 48 with
emulated mouse output consisting of changes in position. In the
case of a gyroscopic tracker with output converted to digital form
such as that used in the Apple Macintosh embodiment, the output of
the head-tracker 28 consists of angular velocity figures. In this
event, the angular velocity samples are simply multiplied by the
time period of each sample to yield a change in position, with each
positional change then converted into mouse mickeys by the tracking
formatter 52.
[0084] The second category of functions performed by the tracking
formatter 52 consists of error correction functions such as those
previously described for the Apple Macintosh embodiment of the
invention. In that embodiment, the tracking formatter 52 performs
low-frequency cut-off filtering, applies a directionally-dependent
scaling factor, and disables one axis of travel when the orthogonal
axis velocity rises above a threshold. These functions could also
be performed in hardware such as an application-specific integrated
circuit or a field-programmable gate array if higher-performance at
high-volume production is desirable.
[0085] The third category of functions performed by the tracking
formatter 52 consists of enhancement functions such as orientation
prediction. This function addresses the pipeline delay between the
instant in time when the head is turned, and the time when the
displayed image is updated to display the new user line-of-sight.
This delay can be calculated to be the sum of the tracker sensing
time, tracker to computer communication time, tracker formatter
processing time, control driver processing time, operating system
and application software processing time, screen enlarger
processing time, and display refresh time. In a typical embodiment,
the sum of these delays can become bothersome, causing a perception
of the display "swimming" with respect to the user's line of sight
changes. This swimming causes perceptual mismatches between the
user's internal proprioceptive cues and external visual cues, which
in severe cases can cause disorientation and nausea effects known
in the virtual reality field as simulator sickness. To avoid such
effects, the current position and velocity of the head in each
degree of freedom can be used to predict the future position, in
the manner of So and Griffin or Azuma and Bishop. By doing so, the
predicted future position can be used as the input to the
processing pipeline instead of the current actual position, thus
decreasing the average mismatch between the proprioceptive and
visual cues.
[0086] FIG. 5 also illustrates the use of a voice recognition
system as a means for inputting control commands and application
data into the invention. The voice recognition system consists of a
microphone 54 disposed near the user's mouth, such as by mounting
onto or within the head-mounted display. The output of the
microphone is input to the computer's audio input port, which
digitizes the audio data. The digital data is then analyzed by a
voice recognizer 56, which may consist of hardware, software, or a
combination of the two. For example, a typical embodiment of the
voice recognizer 56 for an Intel/Microsoft architecture would
consist of Dragon Dictate software by Dragon Systems (Newton,
Mass.), running on a SoundBlaster audio board by Creative
Laboratories (Milpitas, Calif.). Regardless of the particular
embodiment of the voice recognizer 56, the output is sent to the
operating system in the form of digital data interpreted as either
commands or content depending upon the state of the operating
system.
[0087] The incorporation of the voice recognizer 56 enables use of
convenience-enhancing commands for purposes such as positioning the
virtual display with respect to the user's line-of-sight, selecting
enlargement factors, controlling tracking, selecting between system
operating modes, and controlling individual computer applications.
For example, position commands include "center me" to center the
user's instantaneous viewport 22 within the virtual display 20,
"top right" to move the instantaneous viewport 22 to the top right,
etc. Enlargement commands include absolute commands such as "Mag 8"
to set the screen enlarger 24 to a magnification of 8 to 1, and
relative commands such as "zoom double" to temporarily increase the
magnification by a factor of two. Tracking control commands include
"lock vertical" to lock-out response to the elevation tracking
function, which simplifies scrolling horizontally across text.
Selecting between system operating modes includes a complete set of
commands for operating the screen enlarger 24, such as "scroll
text" to enter the enlarger's text scrolling mode. Finally,
application control commands are application-dependent and
available commercially as libraries, which typically include most
or all mouse-accessible functions such as "page down", "font:
Times", "edit: cut", etc.
[0088] FIG. 5 additionally illustrates a spatialized audio
generator 58, which is used to alert the user to computer-generated
events occurring outside the user's instantaneous viewport 22. This
is done by providing the user with slightly different signals in
each ear via a pair of loudspeakers or stereo headphones 60, with
the differences calculated to simulate directionality via slight
delays between the nearer ear's signal and the farther ear's
signal, slight reduction in high-frequency content in the farther
ear's signal, and other spatial processing as is commonly known in
the art. The spatialized audio generator 58 can be constructed from
commercially-available components such as a SoundBlaster audio
board from Creative Laboratories (Milpitas, Calif.), which includes
audio spatialization software as a standard feature. The input to
the spatialized audio generator 58 is provided by the operating
system 42 for simple alerts such as "beeps" signifying an error or
other message window, and may be provided by the application
software 44 or the screen enlarger 24 for more advanced messages
such as synthesized voice messages or text-to-speech
conversion.
[0089] In FIG. 5, it is noted that the control driver 48 contains a
scaling factor used to adjust the amount by which the instantaneous
viewport 22 moves across the virtual display 20 per degree of head
rotation. In most instances, this scaling factor is set so that the
virtual display 20 appears fixed in space while the instantaneous
viewport is scanned across it. However, for extremely high
magnification factors, fixing the virtual display can be
problematic, as the user's head may be required to rotate more than
is comfortable to scan from one edge of the virtual display to the
opposing edge. Under such conditions, the present invention may be
configured by the user with a different scaling factor, which
increases the amount by which the instantaneous viewport 22 moves
across the virtual display 20 for each degree of head rotation.
When viewed by the user, this results in the virtual display
appearing to move across the user's instantaneous viewport 22 in a
direction directly opposite to that in which the user is scanning.
*Because the instantaneous viewport 22 and the virtual display are
both moving in opposite directions, scrolling appears to be faster,
but the user can scan from one edge of the virtual display 20 to
the opposing edge with a smaller total head rotation. This approach
to utilizing the present invention is deemed spatial field
compression.
[0090] It is also noted in FIG. 5 that a snap-back function may be
included within the control driver 48, wherein data from the input
controller 16 is used only for temporary repositioning of the mouse
pointer 32 and instantaneous viewport 22 within the virtual display
20. Specifically, this function records activity of the input
controller 16 while such activity is being used to control the
displayed imagery. Once such activity ceases, the inverse of the
recorded activity is fed to the operating system 42, which
snaps-back the image displayed in the instantaneous viewport 22 to
that which would be viewed in the absence of the input controller
16. The result of this snap-back function is that the virtual
display 20 is maintained at a fixed location in space, which may be
temporarily modified by use of the input controller 16, but is
returned to following use of the input controller 16.
[0091] It is also noted in FIG. 5 that additional image processing
may be performed by the screen enlarger 24 or elsewhere in the
processing pipeline to incorporate additional functions which may
be desirable for visually-impaired users or other applications. For
example, a common feature in commercial screen enlargers consists
of contrast reversal, where instead of displaying black text on a
white background, white text can be displayed on a black
background. This improves text readability for some users. Another
potentially useful feature is image enhancement, wherein the
imagery is digitally enhanced to strengthen edges, which improves
resolution ability for some users.
[0092] Finally, in FIG. 5 it is noted that if the screen enlarger
24 is set to an enlargement factor of one-to-one or omitted
entirely, and a display driver 46 providing a virtual desktop
function such as the MGA Millenium by Matrox (Dorval, QC, Canada)
is used, then the present invention can be used in an identical
fashion by a non-visually-impaired user for purposes of accessing
large areas of a virtual desktop, which enhances tasks such as
simultaneous use of many individual computer applications.
[0093] A further embodiment of the present invention is illustrated
in FIG. 6, which shows the invention applied to magnification of
real-time imagery. In this embodiment, a video camera 62 and a
video frame grabber board 64 are added to any of the previously
described embodiments. The video camera is then mounted in a
stationary position and aimed at an image to be enlarged 66.
[0094] This image to be enlarged 66 may be a small object to be
magnified such as text in a book, or may be a distant object to be
resolved such as a blackboard in a classroom lecture. Each frame of
video captured by the video grabber board 64 is output to the
system bus as application output data by software included
commercially with the video frame grabber board 64, and fed to the
screen enlarger 24. The screen enlarger 24 magnifies the imagery,
creating a virtual display 20 of the image to be enlarged 66 that
occupies a larger angular extent as seen by the user than does the
image to be enlarged 66. The head-mounted display 26, head-tracker
28, tracking formatter 52, and control driver 48 are then used as
previously described to provide an instantaneous viewport 22, which
may be positioned at any convenient point within the virtual
display 20 by turning one's head. In this embodiment, improvement
is made upon earlier closed-circuit television inventions for the
visually-impaired in that the camera captures the entire image to
be enlarged 66 at all times, instead of moving with the user's head
or hand and capturing just the amount of imagery that can be
displayed within the instantaneous viewport 22. By doing this,
spatial awareness is maintained, but jitter in camera motion is not
magnified to become disruptive to the user. In addition, by
interposing a computer within such a closed-circuit television
loop, any image may be instantly saved to permanent memory with a
single keystroke for later review, editing, or printout.
[0095] While the invention has been shown and described with
reference to a particular set of embodiments, it will be understood
by those skilled in the art that various alterations and
modifications in form and detail may be made therein. Accordingly,
it is intended that the following claims cover all such alterations
and modifications that may fall within the true scope and spirit of
the invention.
* * * * *