Heads-up display can be built into eyeglasses
By David Lieberman
EE Times
(04/20/99, 12:00 p.m. EDT)=20
SAN JOSE, Calif. =97 A new head-mounted display (HMD) venture, MicroOptical=20
Corp., will demonstrate an unobtrusive display next month that can be clippe=
d=20
onto or integrated into conventional eyeglasses. A step beyond the latest=20
lightweight, ergonomic headgear, MicroOptical calls its Eyeglass Display the=20
first truly practical HMD.
The HMD arena is due for a dose of practicality, sources said, having failed=20
to move much beyond the heavy, expensive headgear for technicians and=20
maintenance workers who absolutely require a hands-free screen. The crop of=20
miniature-LCD technologies brought to market within the past year is a breat=
h=20
of fresh air for HMDs, however. MicroOptical's design is based on such an=20
LCD, but the company applies the display to the wearable-monitor problem in =
a=20
novel way.=20
"The conceptual demand for HMDs is very high but nobody's gotten the=20
ergonomics right," said Tom Holzel, vice president of sales and marketing fo=
r=20
MicroOptical (Westwood, Mass.), which will demonstrate the Eyeglass Display=20
at the at the Society for Information Display conference in San Jose, Calif.=20
Holzel called the integrated version "a featherweight personal display with=20
an appearance nearly indistinguishable from conventional glasses. We can=20
build this monitor into prescription eyeglasses, safety glasses, military=20
goggles, whatever. We just need a couple of millimeters of glass to shoot=20
light into from the side."=20
Using eyeglasses as "an integral part of the optical train" is the=20
breakthrough that allows the design to shed bulk, said Holzel. The=20
conventional HMD positions a display in front of the eye, but MicroOptical=20
breaks the problem down into two tasks =97 image creation and image=20
presentation =97 to create a very unobtrusive HMD.=20
The company locates the miniature LCD in the temple piece of a pair of=20
glasses or in an L-shaped optics module that clips onto the temple. The=20
"screen" is a tiny lens/mirror combiner that sits in front of the eye,=20
residing on a transparent stalk or integrated into the eyeglass lens itself,=20
and reflecting the image into the eye. The optical path from display to=20
combiner goes through the stalk or lens.=20
A spin-off of miniature-LCD maker Kopin Corp. (Taunton, Mass.), MicroOptical=20
was founded in 1995 and captured a two-year grant from the Defense Advanced=20
Research Projects Agency (Darpa) in 1996 for a headgear project. The=20
company's part of the project was to develop a compact microelectromechanica=
l=20
system (MEMS) that could fit into the temple of eyegear, initially a=20
scanning-mirror system that directed light to the eye via optical fiber.=20
Then, said company founder and chief executive officer Mark Spitzer,=20
"microdisplays came on real fast and we didn't have to do a wiggling scanner=20
anymore." Instead, the project adopted miniature active-matrix LCDs and=20
active-matrix electroluminescent displays as its media.=20
Late last year, the company completed its first round of venture-capital=20
funding and nabbed a second Darpa grant to further develop the current optic=
s=20
for military applications. The technology is "ready now" for commercial use,=20
said Spitzer. "It's easy to build something you're going to look at for a=20
minute, but for something you may look at for an hour, that's a different=20
story."=20
'See-through' monitor
Besides its small size and light weight, what's unusual about the Eyeglass=20
Display is its "minimal occlusion," Spitzer explained in a private=20
demonstration for EE Times this month.=20
"This is the first real ergonomic breakthrough to make this [HMD] thing=20
practical," Holzel said.=20
With this "see-through" monitor technology, the eye easily focuses back and=20
forth between the monitor image and the real world beyond it, and the user=20
views the image without feeling cut off from the world. "Think in terms of=20
adding information to the normal view," said Holzel, "or superimposing=20
information on the normal view."=20
Such superimpositions, he said, "might be an image of a night-vision camera=20
mounted in a soldier's glasses. A firefighter might use it with a special=20
camera to see through smoke, a diver to see through tepid water, a fighter=20
pilot to aim a missile. Or you can simply watch your personal TV or computer=20
screen on an airline without caring whether the guy in front of you leans hi=
s=20
seat back all the way."=20
Spitzer said that MicroOptical has already sold a variety of optometrists an=
d=20
opticians on the concept of the integrated monitor. "There is a very nice=20
distribution channel of people in place who fit optical devices to the head,=
"=20
he said.=20
The company has delivered a 1/4-VGA color HMD to Darpa and there's one now i=
n=20
use at the MIT Media Lab, the latter integrated into a set of prescription=20
eyeglasses. Based on a CyberDisplay miniature LCD from Kopin, the monitor=20
weighs 30 grams in the clip-in version, 100 grams in the built-in version,=20
and requires 50 to 80 milliwatts, including its LED light source. Its virtua=
l=20
image can be adjusted, Holzel said, "to float at any comfortable distance,=20
from 2 feet to infinity." Diagonal field of view is 12 to 15 degrees.=20
Holzel promised that a full-VGA color version would be ready by the SID=20
conference. An SVGA version is also in the works. The Eyeglass Display=20
beta-test program kicks off next month, with clip-ons available to qualified=20
OEMs for $1,500 and an integrated version for $5,000.
http://eet.com/story/OEG19990420S0009