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Gary N. Boone gboone@cc.gatech.edu
Georgia Tech www.cc.gatech.edu/~gboone
Forget Computer Screens. Jack In Your Eyeballs.
by Kristi Coale
4:49am 5.Mar.97.PST Todd McIntyre has seen the computer
screen of tomorrow, and it closely resembles the human
body - or at least a very small part of it.
"You already have a high performance screen, it's called
the retina," said McIntyre, vice president of business
development for Seattle-based Microvision.
Microvision's Virtual Retinal Display (VRD),
demonstrated Tuesday at the Association for
Computing Machinery (ACM) conference in San Jose,
would replace the computer screen with the human
retina and use colors to generate its images. It would be
used in personal display systems - whether mounted on
glasses, in a headset, or in a standalone device - and
draw on the tissue's natural ability to process images.
The human eye is adept at filling in information as it
scans along a picture or line of text. All one needs is to
be shown the way a picture or sentence is headed to fill
in the rest, said McIntyre.
For example, if a person sits in a dark room shining a
flashlight up at the ceiling, he or she will see only the
one spot of light. But move the light rapidly back and
forth across the ceiling, and the eyes can fill in the other
parts and "see" the whole ceiling, McIntyre said.
A VRD works similarly, except that a hand-held or
head-mounted device contains the scanners that draw
the image on the retina. These scans travel through
oscillating mirrors which direct the beam through the
iris and onto the retina, where the eye constructs the
image. The VRD scans at a rate of 18 million pixels per
second, and a "screen" is refreshed at a rate of 60 times
per second.
The resulting image, projected through a device that is
close to the eye, appears at arm's length in VGA
resolution (640 by 480 pixels). Although Tuesday's
demonstration was in black and white, McIntyre said
the VRD will present more of the color spectrum than
current cathode-ray tube and liquid crystal digital
technology.
McIntyre said the VRD will likely see use in military
applications - in planes and on helmet-mounted devices
to help keep troops informed on their fellow soldiers'
positions, of emergencies, and of their own locations. It
will certainly lead to smaller computers - devices small
enough to fit into a cellular phone to allow people to
view documents, an activity that isn't currently possible
with LCD screens, he said.
The problem with miniaturization of display systems,
said McIntyre, is that LCD is not energy efficient
because of the back-lighting used. It gets harder to read
when the screen gets smaller. By contrast, the VRD
uses a few nanowatts of power, so small that scientific
instruments cannot measure it.
For those who might see personal display devices as
another screen that will cause severe strain on the eye,
McIntyre described the VRD's light intensity level as a
comfortable level. The VRD generates light that is
10,000 to 100,000 times below the ANSI threshold for
exposure to visible light.
"[Fear of lasers in the eye] is more of a perception
issue," said McIntyre. "When people intuit how this will
work just like the retina processes light, they'll accept
it."