The document describes the development of the eCase, a portable handheld device with a high-resolution liquid crystal on silicon (LCOS) display for accessing the internet and documents remotely. User focus groups helped determine that the ideal device would be small like a mobile phone but with a full-screen, high-quality display. The resulting eCase uses an SVGA resolution LCOS display, Intel StrongArm processor, and Microsoft Windows CE operating system to provide internet access, document viewing and synchronization in a portable form factor.

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Portable Internet Appliance with Virtual SVGA Display
Al Hildebrand, David Brooks, Jack Morris, Adam Watkins, Don Porter
Inviso, Inc., Sunnyvale, CA
Abstract
An SVGA resolution, liquid crystal on silicon (LCOS)
microdisplay was embedded into a highly portable, hand-held
appliance for uses such as remote internet and information
access. The resulting product was brand-named “eCase” to
reflect the notion of an electronic briefcase. Due to its high
resolution display, the eCase can store and retrieve documents in
their original format for personal viewing. Unique magnifying
optics allow near to eye viewing of the images with great clarity.
Objective and Background
Over the last three years, we have developed a robust liquid
crystal on silicon (LCOS) microdisplay with SVGA (600x800
pixel) resolution directed toward embedded, near to eye, virtual
image applications. We found that adoption of our embedded
microdisplays would be accelerated by our development of
magnifying and illumination optical systems including the
requisite control electronics, which otherwise our customers
would have to independently develop (or even worse,
independently tool for production). Our business activity is now
largely based on delivery of complete display systems, with optics
and ASIC’s tooled for volume production.
Our interest in embedded high-resolution displays was based on
the observation that despite the large variety of available mobile
computing platforms, all have required a compromise between
pocket-size portability and display resolution. We wished to
achieve a highly portable device form-factor, yet one which
allows users to electronically access all of the types of documents
of the typical desktop environment. To achieve this goal, we made
the critical assumption that the targeted users would adapt to a
near to eye display usage model if the display were to provide an
image of the document equivalent to a full size laptop screen. This
assumption was backed up by careful focus-group studies, which
also confirmed that display image quality would be quite
important to near to eye acceptance.
A comprehensive market research study early last year [1] posed
the following question to a large `population of mobile device
users: “How much more appealing would it be to use a portable
device with an enhanced display to access the Internet wirelessly
than to use a handset or portable device with a standard display?”
Table 1 shows the strong preference for an enhanced display.
44% Much more
29% Somewhat more
19 % No Opinion
8% Less appealing
Table 1: Wireless Data Users Study
We decided that our customers would benefit from a reference
platform that incorporated our display form-factor with a usage
model that included the ability to synchronize documents with the
desktop application environment. In addition, we incorporated a
high performance browser to provide for the downloading of web
pages from the internet without the need for reformatting of the
pages. The result of this effort is the “eCase” product line, a truly
mobile electronic briefcase and more.
User Requirements
We conducted focus groups selected from four categories of
users: highly mobile professionals, average professionals, youths,
and non-professional female parents. The groups were given a
wide assortment of portable devices to handle and use during the
sessions including pagers, cell phones, PDAs, and a variety of
foam models we prepared for these sessions. Using a clinical
psychologist who specializes in behavioral issues in the use of
electronic devices, we drew conclusions about desired
applications, usage issues, and physical requirements.
Applications
All user groups expressed strong interest in remote access to a
wide variety of data, the most important being desktop
synchronization, email access, and internet connectivity. Most of
the users had significant applications experience using desktop
computers, and many professional users made significant use of
laptops or palm held devices. As with all Palm and Pocket PC
devices, synchronization with desktop or network based databases
is viewed by users as mandatory, through a docking station or
even remotely when out of the reach of the PC.
Email access is also a mandatory application for any mobile
computing device, but users define email much more broadly than
just short messages. For most professional users, email has
become the most important vehicle to receive and forward
documents as email attachments. In another extensive study [2],
63% of respondants said attachments were extremely or very
important and another 21% answered somewhat important. These
attachments range from word documents, spreadsheets,
presentations, to HTML or XML formatted pages.
Perhaps most importantly, internet connectivity is a highly desired
application even for remote devices, and users require browsing of
any and all content, not just that which can be extracted to fit a
cell phone sized mini-display. Of course, remote Internet
connectivity is essential to mobile database synchronization, email
access, and many other desired applications such as MP3
downloads and gaming.
Physical Requirements
It was no surprise that users showed a strong preference for some
of the smallest devices they were given to handle. Portability
really has come to mean in-the-pocket or belt-worn comfort.
Users have come to consider the mobile phone form factor as the
definition of portability. With fewer pagers in use today than
mobile phones, there was not a strong desire by users to select the
smallest of the foam models once a comfortable size was attained.

2. Page 2
We concluded that the thickness of the device should be less than
25-mm and set a long term target of 15-mm. Thickness is perhaps
the most sensitive dimension for pocket sized devices, and as will
be shown below, thickness has a critical impact on display design.
Width is also a sensitive dimension to users for both pocket
comfort and handling the device, and for handling, width and
thickness (or girth) need to be taken together relative to the
dimensions of the hands of the user population. It was concluded
that 65-mm was the largest acceptable width, with 45-mm as a
long-term target. Height is a less critical dimension unless it
exceeds 125-mm.
To most users, weight becomes important when it exceeds 6-oz.,
and 8-10-oz. becomes heavy in the pocket. The single highest
source of weight is the battery, which creates a conflict between
battery life and weight/size. Power consumption needs to be on
average less than 1-watt, with a target of less than a half-watt
based on continuous operation.
Usage Model
With applications having been defined by these user expectations,
we drew several important conclusions about the usage model.
The first issue users have to deal with is how quickly the device
can be put to use. Mobile phones awake instantly from a sleep
mode, and pagers are always on. Users are not satisfied with the
long boot-up times of the laptop computers many carry for mobile
computing. Handheld devices must be instantly deployable.
Once the device is activated, the immediate issue users have to
deal with is the user interface. For the most part, users are
completely conditioned to the graphical user interface (GUI), and
this is even more true in a mobile computing environment. As
mobile phones have been embedded with data oriented
applications, stacked menus have given way to touch screen GUI
controls much like palm sized PDA devices.
As various sample devices were handled and used during focus
group sessions, display legibility became a critical issue to the
users. At first, the issues relate to contrast and brightness. Mobile
users experience a variety of ambient conditions that make the
displays of many handheld devices difficult to read, and many
display suppliers are finding a variety of solutions to this problem,
such as emissive and reflective screens.
After these focus groups had explored the issues relating to the
existing usage models of mainstream mobile devices, we
introduced the groups to the near-to-eye (virtual image) display.
There was an immediate recognition that this display provided
real improvements in contrast and brightness, and there was the
immediate recognition by the user groups that they were seeing
images of resolution and legibility comparable to their laptops or
desktops. There was typically surprise at the quality of the image.
However, the near-to-eye display demonstration introduced the
new issue of user comfort with a monocular viewer. In particular,
there is an issue of what to do with the other eye. When each eye
sees a strongly different image, there is the phenomenon of
binocular rivalry, which can be a discomfort to the user. Users of
camera and camcorder viewfinders deal with this issue largely by
squinting with the other eye. Other solutions are discussed later in
the description of our designs.
In further discussions, the desirability of the display attributes is
very much related to the applications the users expect in using the
device. This ultimately becomes the central design issue in the
pursuit of an embedded near-to-eye display product.
In the end, much of our focus group attention was also paid to the
issues of user input to the devices. Users are most familiar with
keys and touch-screens for data entry and with voice for person-
to-person communications. It was clear that users were just
coming to grips with the issue of entering data on a handheld
device. In most environments, at least one hand is occupied in
holding the device itself, but in certain other environments, the
use of a miniature or fold-out qwerty keyboard allows ten finger
key entry.
While speech input seems an attractive option, users are a bit
skeptical since there is little other than voice dialing on some
recent mobile phones that demonstrate this technology. As a result
of the complexity of the input issues, the focus groups were not
effective in defining clear-cut user preferences. We realized that
we would have to develop a variety of input options and conduct
further focus groups to refine data input.
Conclusions
Integrating what we learned from the various focus groups, we
drew the following conclusions:
• Users would have a strong preference for a device which
provided a full screen, color display, especially if it met the
size and weight criteria of the popular mobile phone
handsets. However, this preference would depend on offering
a sophisticated mix of applications and data access.
• Monocular, near-to-eye use would be acceptable for minutes
at a time, but not likely for prolonged (hours at a time)
viewing.
• A careful crafting of the industrial design would be required
to satisfy the form-factor of a hold-to-the-face device,
especially regarding issues such as cursor control for the
GUI, location of keys, and fit to the hand.
• The most important applications involved access to data and
images and the ability to view that content. We felt users
were unlikely to need to compose documents or messages of
any great length, nor were they likely to need to process
documents, presentations, or spreadsheets.
Display Specifications
Resolution and Image Size
For a number of reasons, we specified a display with SVGA
resolution and a field of view of 34 degrees. This matches well to
the physiology of the human eye and creates a viewing experience
very close to most computer monitors or laptops. At this
magnification, a pixel subtends an angle 2.0-arc minutes to the
eye, which is the resolution of the average users visual acuity. In
addition, it matches the 100 pixel per inch pixel density of the
typical monitor.
Other reasons for this choice are based on the collection of data on
Web site hits. Statmarket [3] has shown that the majority of
monitors used for viewing Internet based information are set to
SVGA (800x600) resolution. As a result most Web pages are
authored for SVGA or higher resolution displays. Unless a
mobile display allows viewing of documents or web pages in the

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form they were authored, the user will have to spend time
scrolling to find the desired information.
Desktop synchronization with access to enterprise documentation
is an important application and requires a resolution to match
those documents. We determined that document synchronization
required 100 dpi equivalent display resolution to provide for an
eight-inch wide document format, and thus an 800 pixel display
width. The 600-pixel display height is just over the half-height of
an eleven-inch document for the 100-dpi resolution.
With the resolution and magnification established, we considered
the ergonomics of a hold-to-the-eye viewer. We did not want
presbiopic users, who need reading glasses to clearly see things up
close, to have to put their glasses on to view the display, so we
placed the image at a distance of two meters, where their vision is
still acute. For myopic users requiring corrective lenses for all
normal vision, we specified a large eye-relief of 30 mm to leave
space for the often quite thick lenses of some prescriptions.
Through straightforward trigonometry, these decisions led to the
requirement that the viewing window dimension be 20-mm by 30-
mm, and as a result, the eyepiece lens diameter must be 34-mm.
LCOS Display Imager
We developed a display meeting these requirements utilizing a
liquid crystal on silicon (LCOS) display module. The display
operates in field sequential color mode and utilizes a reflective
mode optical path. The liquid crystal module consists of a CMOS
silicon backplane, liquid crystal material, alignment layers and
ITO coated cover glass. The silicon backplane is built on a 3.3V
standard CMOS process utilizing chemical-mechanical polishing
(CMP) to ensure wafer flatness. Wafer passivation is highly
transparent and aluminum electrode reflectance averages about
90% over the LED illumination spectrum. Pixel pitch is 11 µm
and the active area diagonal is 11mm. The aperture ratio for this
device is approximately 89%. This LCOS display imager and the
supporting electronics have been described previously [4], as the
imager has been embedded in other devices. An important
attribute of the imager is that high resolution, color images are
obtained with far less than a watt of power consumption.
Display Optics and Illumination
We had also developed a catadioptric magnification optic that
meets the specifications of the embedded display required for
achieving the needs of the eCase device. This magnifier has also
been integrated with an illumination system that provides the front
illumination required by reflective displays. The illumination
system is unique in that it creates a very large and uniform
extended source size. Both the magnification and illumination
systems are extremely compact as described previously [4,5].
System Architecture
We obtained early samples of the Intel StrongArm 1110 Processor
that we selected based on its very high processing power and low
power consumption. The SA1110 is a 32-bit processor, which we
run at 206 MHz. We incorporated 32 MB of RAM, 16MB of
Flash, and 2MB of ROM. The system provides expansion through
a single Type II compact flash slot which supports Compact Flash
Media and Compact Flash Peripherals. The systems architecture
of the eCase is shown in Figure 1, which was laid-out on two
stacked PCBs to fit the form-factor of the ID.
Navigation is provided through five front panel buttons (a push-
on/push-to-talk button and four quick launch customizable
application buttons) and through a touch-pad also located on the
front panel. The touch-pad controls a cursor that provides
navigation of the graphical interface.
Communications is provided through both USB and serial ports.
These connections are primarily utilized in desktop
synchronization. Both wired (56k modem and Ethernet) and
wireless connections can be obtained through CF Peripherals.
Audio input is enabled through an embedded microphone, and
audio output through an integrated speaker or a stereo jack. Audio
functionality is also important in the development of speech based
user interfaces. We have demonstrated very efficient speech based
navigation of databases such as contact files.
Figure 1: Systems Architecture
A highly unique aspect of the system architecture is that the
embedded display system sits right on top of the SA1110 bus and
is treated by the system software as a frame buffer.
The architecture is very similar to the highly successful Compaq
iPaq™, which provides exceptional functionality in a handheld
device. We believe we have distinguished the eCase from other
Pocket PC devices through the display resolution of the eCase,
and the emphasis we have placed on specific applications
software.
SA1110
32MB RAM
16MB Flash
2 MB ROM
CRASIC/AIC
Speaker/Jack
Mouse click
3430
Display
System Board Power Board
Compact
Flash Slot
USB/Serial
Port
Flex
Touch-pad
Buttons
Push-on/
Push-to-talk
Microphone
Audio Codec
Power
Regulators/
Charger

4. Page 4
System Software
We selected Microsoft Windows CE™ as the operating system for
the eCase platform. Of the embedded operating systems already
ported to the SA1110 processor, WinCE was the only well
supported OS that had a high resolution display driver, a high
performance browser, and synchronization to Microsoft Outlook.
WinCE was developed specifically for advanced 32-bit embedded
systems and is highly customizable to facilitate a small footprint.
The architecture of Windows CE is shown in Figure 2.
WinCE executes in place out of ROM, which for the eCase is a
2MB boot ROM. The device drivers run as normal processes in
the system, with access to all OS services, including the interrupt
routines, which means fast wake up of these drivers. Processes
needed to maximize performance can be locked in memory rather
than paged. This and the fact that the kernel is written to provide
low latency times all results in a very user responsive interface.
WinCE is also very modular, made up of components from which
OEMs can select only the functionality required, new components
can be added as new features become available. For example, the
eCase does not utilize the word processing or spreadsheet
modules, which have big footprints. The CE OS utilizes the
Win32 API allowing developers to use established applications
constructs in an embedded environment.
Figure 2. WinCE Architecture
Windows CE 3.0 includes two versions of Microsoft’s browsing
technology, Internet Explorer. The eCase uses the Generic
Internet Explorer 4.0 (GENIE), which is derived from the desktop
version. GENIE is the most desktop-compatible, feature rich
browser control for an embedded OS, and includes HTML version
4.0 , IE 4 Document Object Model, MSXML 2.0, JScript 3.0,
DirectX API, and ActiveX controls.
Industrial Design
The industrial design for the eCase is shown in Figure 3. The
industrial design contractor had prior experience with portable
electronic products, but the ID went through five revisions to meet
the minimum ergonomic needs of this form-factor.
Figure 3: eCase Industrial Design
Conclusion
The eCase concept product is a useful example of the use of novel
microdisplay construction in a unique form-factor, taking
advantage of the fundamental technical advantages offered by this
new display category.
The eCase has received widespread recognition as an important
and innovative new product. In November, 2000, the eCase
received a J.P. Davis & Co. Concept Product Award at the Fall
Comdex 2000. A month later it was announced that the eCase had
won the 2000 Information Display Magazine Display Product of
the Year Gold Award. Deutche Telekom showcased the eCase in
its own booth at CeBIT 2000 in Hannover, and Microsoft
Corporation has showcased it often as an innovative Windows CE
product.
Acknowledgments
The authors wish to thank Dan Schott and his colleagues at Three-
Five Systems for fabricating the liquid crystal devices on Inviso
backplanes used in these displays. The authors also wish to thank
the Inviso team, especially, Neil Bergstrom, Richard Wu, Xi Lin,
Johnathon Hsueh, Dana Chase, Ed Cruz, Dan Humphreys, Dick
Huston, Jinsuk Kang, Herb Lara, and Gang Xu.
References
[1] Cahners In-Stat Group, Wireless Business Study 2000
[2] Cahners In-Stat Group, Wireless Data Conference Call, July
20, 1999
[3]Statmarket, Webside Story, March 15, 1999.
[4]Bergstrom, N., et al, “Ergonomic Wearable Personal Display”,
SID International Symposium, Digest of Technical Papers, Vol.
XXXI, May 16-18, 2000
[5]Hildebrand, A., “High-Quality Optics for Microdisplays”,
Information Display Magazine, April/May 1999.
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