Virtual Research Systems FS5i User manual

User’s Guide
FS5i
Virtual Research Systems, Inc.

December, 1995
The information contained in this publication is believed to be reliable, but Vir-
tual Research Systems, Inc. makes no warranties as to its accuracy or com-
pleteness.
Copyright 1995 Virtual Research Systems, Inc. All rights reserved.
Virtual Research Systems, Inc.
2326 Walsh Ave.
Santa Clara, CA 95051
phone: [phone]
fax: [phone]
e-mail:
[email protected]

FS5i
The FS5i is the integration of our top of the line FS5 HMD and our
FSCAN scan converter. The result is an HMD that accepts multiple signal
formats without the headache and expense of additional cabling. The FS5i
maintains all of the functionality of the two separate devices, incorporating them
into a single, rack mountable enclosure. A new feature of the FS5i is a VGA
monitor output that replaces the field sequential monitor output of the FS5. This
allows the user to drive the HMD and a monitor without a VGA splitter or
additional cabling.(monitor out not available with field sequential input format.)
In addition, selectors for input formats and mono/stereo have been
relocated to the front panel.
The top cover of the enclosure need only be
opened to fine tune color adjustments.(normally not needed)
Initially, your FS5i will be shipped with separate manuals for the FS5 and
FSCAN. The functionality of the FS5i is the same as the separate units with the
above exceptions. By following the guidelines in the separate manuals, one
should find the setup of the FS5i HMD to be simpler. A new, integrated FS5i
manual will be shipped to you as soon as it is available. If you have any
questions or problems please contact Virtual Research for prompt assistance.

Contents
ii
TABLE OF CONTENTS
INTRODUCTION TO THE FS5
SAFETY ISSUES
FS5 CONTROL BOX
Inputs
Video Input
outputs
MECHANICAL ADJUSTMENTS
Donning the FS5
Interpupillary Distance (IPD)
Fore/Aft motion of shell
Display Height Adjustment
Overlap Adjustment
Ratchet Knobs
Headphones
Cable Positioning
OPTICS
POSITION SENSORS
Traeker Mounting
Reducing Tracker Jitter
PIN OUT INFORMATION
SYSTEM CONFIGURATION INFORMATION 23
Intergraph Platforms 23
1
2
14
14
15
15
16
16
17
17
17
18
19
19
21
22

Contents iii
Division ProVisionlO System Configuration
SGI Reality Engine System Configuration
SGI Indigo2 Impact System Configuration
Other Systems and the F-Scan Converter
THE F-SCAN CONVERTER 26
TROUBLESHOOTING 27
24
24
25
25

ChaDter 1 Introduction 1
Chapter 1
Introduction to the FS5
FS5 is our new high performance head mount display (HMD) . At the heart of
the product are 1” cathode ray tubes (CRTs) capable of resolution and image
quality far superior to any available flat panel displays. The CRTs are black and
white tubes which run field sequentially; red, green and blue are created by
color shutters mounted in front of the CRTs. Although most users will drive
the FS5 to VGA resolution, the CRTs are capable of up to 800 pixels horizon-
tally.
The FS5 optical system excels as well. A custom design using aspheric sur-
faces on plastic elements allows us to achieve a 55” field of view (FOV) while
maintaining sufficient eye relief for glasses wearers. By using plastic, we avoid
the weight problems of glass elements.
Mechanically, the FS5 retains many features developed and perfected in our
LCD product, the VR4. The rugged front shell protects the display components
and requires only two adjustments--interpupillary spacing and fore/aft posi-
tioning.The headband is a proven performer with thousands of hours of trou-
ble free experience in the VR4. The high flex cable has an extruded jacket for
abrasion resistance.
Audio rises to a new level with the FS5. These Sennheiser closed cup head-
phones are the best compact headphone we have found.Whether your source
is simple monaural cues or top-of-the-line stereo, these headphones
will perform.
The FS5 control box has superior functionality as well.A set of front panel
LEDs give instant status information. Brightness and contrast adjustments that
control both eyes together are also available on the front panel. Full right and
left RGB setup and gain adjustments are also easily accessed inside the control
box if fine tuning is desired.
Standard field sequential input is available from several image generators, in-
cluding SGI and Division. A similar field parallel format is available from
In-
tergraph platforms. Appropriate connectors are easily accessible at the control
box rear panel.
For other signal sources, an optional converter is available. The F-Scan Con-
verter accepts either RS-170 RGB or 6OHz VGA stereo signals and drives the
FS-5 directly.
The true test of any product is not the features list, but how it performs in your
application. We expect that the blend of features designed into FS5 will work
well for you. But if you have any questions or problems or special design re-
quirements, please give us a call. We’ll do whatever we can resolve your ques-
tions and make your application successful.

Chapter 2 Safety Issues 2
Chapter 2
Safety Issues
We take pride in building a safe product that will satisfy your requirements.
But the nature of our product--an electronic display device that you wear on
your head--creates the potential for problems. We strive to understand and
minimize the safety hazards associated with our head mount displays.
As an HMD user, you should understand those hazards too.With that under-
standing, please make an informed decision about using this or any head mount
display product.
Blocked vision and hearing
By its nature, a head mount display blocks the user’s vision and hearing. The
danger of tripping over cables or other obstacles becomes a real concern while
immersed in the virtual world. As system manager, you must provide an envi-
ronment that does not allow the. HMD user to fall or otherwise injure
him/herself. As a system user, you must survey your physical environment be-
fore entering the virtual environment to avoid problems. We recommend using
FS5 only while seated to avoid tripping hazards.
Eyestrain and other optical effects
FS5 will cause eyestrain if the interpupillary distance (IPD) is set incorrectly.
Like all head mounts, it is likely to cause some eyestrain effects even when cor-
rectly adjusted. This eyestrain stems from several causes, with perhaps the
most significant being the fixed focal plane which conflicts with the variable
depth cues present in the imagery. There is no technology we are aware of that
corrects this conflict.Other potential sources of eyestrain include optical aber-
rations, distortion, mismatch of computer imagery with mechanical configura-
tion and display mismatch.
If you experience noticeable eyestrain, review and correct your mechanical ad-
justments and software configuration. If eyestrain persists, limit or end your
use of this device.
Lice/other pest transmission between users
Although we have not had any instances of user’s reporting lice transmission to
us, there has been at least one anecdotal report of lice transmission in a public

Chapter 2 Safetv Issues 3
use HMD. There are sprays available that will kill lice on furniture and cloth-
ing. Two of these are RID and A-200. Both are available in drug stores. We
don’t have information on the effectiveness of these sprays on HMDs and en-
courage you to research this if you are considering a multiple user application.
These sprays are hazardous and you need to judge the benefits vs. risks of us-
ing them. Remember to read and follow the manufacturer’s directions.
Alcohol wipes are useful for cleaning the HMD between users. Alcohol will
remove skin oil and makeup that have transferred to the HMD. As far as we
know, alcohol has no effect on lice.
Electrical Shock Hazard
The desktop power supply produces 12V, - 12V and 5V DC.All three voltages
are present in the control box. The HMD cable carries the 12V power to the
HMD. These voltages are too low to represent a significant hazard, even with
the control box open to make color adjustments.
The enclosure at the rear of the HMD contains high voltage circuitry required
for the CRTs. This enclosure should be opened only by trained, authorized
technicians.The voltage is sufficient to give a significant shock if contacted.
The voltage is also sufficient to arc across a few millimeter gap to any conduc-
tive surface--like a finger or tool. In our experience the shock from this voltage
is bothersome, but not dangerous because the current level is quite low. How-
ever, under worst case circumstances the effects would undoubtedly be more
severe (e.g. pacemaker users, etc.).
The top bar of the headband contains a cable bundle that carries these high volt-
ages to the front of the HMD. Do not cut, drill, clamp or otherwise damage this
portion of the headband.
The front portion of the HMD consists of two display units within a shell.The
wiring from the headband to the display units and the display units themselves
have the same voltage levels described above. There are no user accessible ad-
justments at the front of the HMD and no attempt should be made to insert fin-
gers, tools or other potentially damaging/conductive items into the front shell.
The shell should be removed only by trained, authorized technicians.
Extremely Low Frequency (ELF) and Very Low Frequency
(VLF) Emissions
Magnetic fields generated by electronic devices (Televisions, toasters, shavers,
household wiring, high voltage lines, -etc, etc, and HMDs) have been reported
to cause a number of severe health problems, including leukemia.There is a
great deal of controversy at this time regarding the validity of these studies.A
number of other studies have found no correlation between these emissions and
health risks.
Test equipment, a standard procedure and test limits for ELF and VLF
emis-

Chapter 2 Safety Issues 4
sions for computer monitors have been developed in Sweden. While this test
seems relevant to head mount displays, the equipment is unsuitable for meas-
uring the fields around miniature displays. There are no standard test proce-
dures, equipment or standards for electronic devices other than computer
monitors.
Because there are so many unknowns surrounding this topic, we elected to
contract an expert in the field to develop test equipment and calibrate that
equipment for us. We have developed procedures for measuring the fields gen-
erated by our products using that equipment. After measuring the fields gener-
ated by our components, we add shielding and/or relocate components to mini-
mize the fields. This seems to be the prudent approach in view of the vast lack
of solid information in this area.
X-Ray Emissions
CRTs are capable of generating x-ray emissions under some circumstances.
Our CRTs operate at voltages below levels that produce x-ray emissions. The
CRT production process includes testing to verify this. The U.S. Food and
Drug Administration regulates CRT products to ensure adherence to x-ray emis-
sion standards. Our product information has been submitted to the FDA for re-
view.
Further Information
If you have questions about any aspect of head mount display product safety,
please feel free to contact us directly. Our address, phone number and e-mail
address are listed at the front of this document.

.Chapter 3 Control Box 5
Chapter 3
FS5 Control Box Box
Inputs
FS5 control box inputs are located on the rear panel:
fi
3
VlDEO INPUT
RIGHT LEFT
I PION
RIGHT LEFT I MONO
Control Box Rear Panel
Audio
The audio jack is a standard stereo 3.5mm mini phone jack. The control box
passes the audio signal through directly to the FS5 headphones; there is no am-
plification or audio adjustment in the control box. Audio signal level supplied
to the control box should be the same signal that would be supplied directly to
stereo headphones.
Power
The control box requires +12VDC, -12VDC and +SVDC. A universal power
supply comes with FS5. The power plug on the FS5 is a 5 pin DIN plug.
CAUTION: IT IS EASY TO DESTROY YOUR FSS--SIMPLY PLUG
IN THE WRONG POWER SUPPLY AND TURN IT ON.
TO AVOID THIS UNHAPPY EXPERIENCE, ALWAYS CHECK FOR
THE COLOR MATCHED BAND ON THE POWER SUPPLY PLUG
AND THE COLOR PATCH ON THE CONTROL PANEL. IF THE
POWER SUPPLY DOESN’T HAVE A MATCHING BAND, DON’T
PLUG IT IN!

Chapter 3 Control Box 6
Because the 5 pin DIN plug is used on many power supplies, there is a real
hazard of plugging the wrong power supply into the
FS5 control box. To re-
duce the risk of this, we have added a REID colored band to the FS5 power
supply and a YELLOW colored band to the F-Scan power supply. Always
check for correct color matching before plugging in a power supply to avoid
making an expensive mistake.
Power SupplyQuick Identification
colored band
RED BAND -- FS5 Power Supply
YELLOW BAND -- F-Scan Power Supply
No Band-- Don’t use!
As a further verification of powersupplies,compare the label to the copies below
be-
FS5 Power Supply
F-Scan Power Supply
One particular example of this problem is the Polhemus Fastrak which also uses
a 5 pin DIN plug. The Fastrak power supply outputs a higher voltage and can
damage the unit

ChaDter 3 Control Box 7
Video Input ~
FS5 accepts three video signal formats:
1) Field sequential
3xRS 170 RGB composite
2) 3xRS170 RGB parallel
3) F-scan format
Background Information on Video Formats
RS170
RS 170 refers to a timing standard developed for television that uses an inter-
laced format with 525 lines per frame, 262.5 lines per field. Frame rate is 30Hz
while field rate is 60Hz. Line rate is 15,575 Hz (262.5 lines X 60 fields).
RS170 RGB
The term RS170 RGB refers to red, green and blue on separate wires, with
RS 170 timing. RS 170 RGB also requires vertical and horizontal (or composite)
sync. We speak of 5 wire RS170 RGB (red, green, blue, horizontal sync and
vertical sync); 4 wire RS170 RGB (red, green, blue and composite sync) and 3
wire RS 170 RGB (red, green with sync and blue).
For reference, our previous generation product--VR4--accepts 3 and 4 wire
RS170 RGB.
FS5 Video Formats
Field
Seaquential 3xRSl70 RGB Composite
This signal is based on RS170 RGB, but is quite different.
Rather than
transmit red, green and blue in parallel, the three colors are transmitted in se-
quence. To transmit all the information, the rate of transmission is increased by
3x. The information is transmitted on one wire. To distinguish the three col-
ors, a longer vertical sync pulse is sent before red. The color order is red,
green, blue.
The timing for this format is as follows:
full frame rate: 30 Hz (same as standard RS170)
full field rate:60Hz (same as standard RS 170)
individual color field rate:
18OHz (3x full field rate)
line rate:
47,250Hz (262.5 lines x 180 fields)
Because RS 170 is an interlaced format, there is some added complexity in de-
fining the order of sending field one and field two. From a timing standpoint,
the most straightforward order of transmission is as follows:
R field 1
G field 2
B field 1

Chader 3 Control Box 8
R field 2
G field 1
B field 2
This order maintains the field
1, field 2, field 1, field 2 cycle that is defined in
RS170 timing. It avoids the timing problems that arise in using the following:
R field 1
G field 1
B field 1
R field 2
G field 2
B field 2.
However, FS5 can accept either order.
Video input connectors are BNC type. Connectors are labeled ‘RIGHT’ for
right eye input while using stereo mode, and ‘LEFT/MONO’ for left eye in ste-
reo mode, or for both eyes in mono mode. These inputs are 750hm terminated.
3xRS170 RGB Parallel (Intergraph RGB):
3x RS170 RGB parallel describes yet another related video format. This format
is a 5 wire video (R, G, B, H sync and V sync) which is run at 3x RS170.
So
the timing is:
Full frame rate: 90
Hz (3x RS 170)
Full field rate: 180 Hz (3x RS 170)
Color field rate:
18OHz (3x RS170)
line rate:
47,250Hz (262.5 lines x 180 fields)
This format has been created because some computer manufacturers (Intergraph
in particular) can generate video at 3x RS 170, but do not have hardware config-
ured to support putting all three colors on one wire. To accommodate systems
like
Intergraph we have developed circuitry to accept 3xRS 170 RGB parallel.
This signal is input on HD15 pin connectors. The FS5 does the work of se-
lecting R, G and B in sequence internally.
The pinout of this connector is given in Appendix 1. Video inputs are 750hm
terminated. Sync inputs are unterminated.
F-Scan Format:
FS5 also accepts a field sequential format that is generated by the F-Scan con-
verter. This format is most similar to the field sequential
3xRS- 170 RGB com-
posite format described above. It differs only in that H sync and V sync are
transmitted on separate wires. The signal is transmitted over a 15 pin to 15 pin
video cable from the F-Scan converter to the FS5.

Chapter 3 Control Box 9
The F-Scan Converter accepts 60Hz VGA or RS 170 RGB. It converts these
signals to the F-Scan Format. This allows use of the
FS5 with graphics
sources that cannot generate an FS5 signal format.
For further information about the F-Scan Converter, contact Virtual Research.
outputs
Control box outputs are located on the front panel of the box.
II
SC =
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--
Virtual Research
= a :
ABCD
VR MONITOR
BRlGHTNESS
0
CONTRAST
0
Control box front panel
Monitor Output
One channel of monitor output is provided at the front of the control box. The
output is from the left eye input. RGB outputs are line driven and 75ohm ter-
minated. Sync outputs are unterminated
TTL level signals.
The output signal format is not standard and will not work with most monitors.
The signal is generated by taking the field sequential input used by the FS5, and
splitting it out onto separate red, green, blue, H sync and V sync lines. This
signal has a field rate of 180
Hz, and the colors are only present on each third
field.
There is a drawback to this approach--because the monitor is only receiving
color signals in every third field, the picture has about l/3 the brightness of a
normal picture. For many applications, this is not a significant problem. But if
your application requires high monitor brightness, this approach would not be
recommended.
We have not done any extensive monitor evaluation, but we have not found any
monitors that are specified at 180 Hz field rate. And in fact, several monitors
we have tested will not accept this field rate.
However, we have discovered that some monitors will operate at this rate. In
our lab we have worked extensively with the Hitachi SuperScan pro 21”. Al-
though it is specified only to
160Hz, this monitor operates at up to 2OOHz.

Chapter 3 Control Box 10
HMD Output
The HMD output is a 26 pin AMP connector. Pinout from this connector is
given in chapter
7 of this manual.
CAUTION: do not plug or unplug the HMD connector while power is
ON at the control box. Always power down the control box before dis-
connecting the HMD.
Status Indicator Lights
There are eight LED status indicator lights located on the front panel of the FSS
control box. These lights are marked with letters A to H. The meaning of each
light is given in the following diagram:
A B
C
D
ON: left eye ON: Left eye
*’ ON: 15 pin inputs ON: no horizontal /,
horizontal
vertical, problem-- selected
sync. present at
frequency out of
HMD disconnected
OFF: BNC inputs video input(s)
range
or no video selected
ON: right eye ON: Right eye ON: 15 pin F-SCAN ON: monoscopic
horizontal vertical problem-- input selected
OFF: stereoscopic
frequency out of
HMD disconnected OFF: 15 pin
range or no video Intergraph input
selected
E
F
G H
Overall Brightness and Contrast Adjustments
The brightness and contrast adjustments located on the front of the control box
will adjust both eyes together. For best image resolution, set brightness so
blacks are just black (rather than gray) and keep contrast low.For a standard
video input, the brightness can be adjusted so high that the entire image will go
to white. Although this should not damage the CRTs, it is a good practice to
avoid overdriving the CRTs this way.
Control Box Internal Adjustments
Selectors for mono/stereo input, F-SCAN/Intergraph input and individual dis-
play setup pots are located inside the control box. To access these adjustments,
you need to open the control box. To do this:
1. Turn off power at the control box.

Chapter 3 Control Box 11
2. Disconnect cables from front of control box.
3. Remove two Phillips screws as shown below from front panel of control
box:
4.
Remove the front panel and bezel from the control box.
5.
Slide the top cover forward and clear of the control box.
6.
Reconnect the HMD connector to the control box output.
To reassemble, reverse the above procedure. Be careful to slide the cover into
the correct channels on the control box base.Use normal caution in working
with the exposed board regarding ESD (electrostatic discharge). The compo-
nents are not highly susceptible to ESD, but can be damaged if normal precau-
tions are not followed.

Chapter 3 Control Box 12
Internal Adjustments are located as shown below:
F-Scan/lntergraph Select -,
Left Vertical
J
Adjustments
Color adjustments
The FS5 SETUP and GAIN pots have been factory set to give a matched out-
put on your HMD. We use an oscilloscope to check output voltage levels for
each color. If you feel the colors are off, it is best to start slowly with changes.
You may find the mismatch is worse rather than better after casual tweaking.
If you do adjust colors, start first with SETUP pots. These are used to set
black level at an even black (rather than greenish black or reddish black for in-
stance). Next use GAIN pots to set white levels (rather than reddish white,
etc.).
All adjustments may be made with power ON to the control box and the HMD
operating. If you experience any problems, it is best to power down the control
box, wait a few seconds, then power up again.

Chapter 3 Control Box 13
Video Input Format Switches
Switch positions as viewed looking down at board are as shown below:
t
Select BNC input
t
Select F-Scan Input
SW4
n
SW3
rl
c
Select 15 Pin input
i
Select Intergraph Input
t
Stereo Input
0
SW2
Mono Input
1
power switch
front of control box
Refer to chapter 8 for system configuration information and to the video input
section of this chapter for details of the specific input formats.
In most cases, we will factory set your video mode switches to match the sys-
tem you are planning to use. You should be able to use your FS5 without any
initial changes to the mode switches.

Chapter 4 Mechanical Adjustments 14
chapter 4
Mechanical Adjustments
Locations of mechanical adjustments are shown in the following drawing:
Donning the FS5
There are several things to consider when first donning the FSS.
1. The top ratchet should be adjusted to bring the sides of the headband down
to the base of the ear. See diagram:

Chapter 4 Mechanical Adjustments 15
2.
3.
4.
5.
The rear ratchet should sit below the base of the skull, as shown in the dia-
gram above.
The cable should fall down the user’s back--not over the shoulder. The ca-
ble weight provides counterbalancing for the display weight.
It is easier to don the
FS5 with the earphones in anup position--out of the
way. After the other adjustments are made, it is easy to bring the earphones
down. While pulling them down, pull them out away from the head to
avoid bending your ear.
IPD, display height, and fore/aft motion adjustments are performed together
to optimize the view.
lnterpupillary Distance (IPD)
IPD range = 48-73 mm. This range is sufficient to cover from 1st percentile
teenager women to 99th percentile adult men. It should also cover a large per-
cent of younger children, but we don’t have statistical information on younger
population groups.
Adjust until both images are evenly visible. Close one eye to
confirm the image
is centered in front of the other eye. Incorrect positioning of the IPD adjustment
will lead to eyestrain.
Fore/Aft motion of shell
Pull shell away for easy donning. Push toward face to maximize field of view
and to block ambient light. Eyeglasses can be worn with FS5, simply leave
fore/aft adjustment near the outer position.
Fore/aft motion is controlled by a detent set screw that is accessible through a
hole at the center of the aluminum bracket at the top inside of the shell.It re-
quires a .050’* hex head wrench to adjust. This tool is provided with the FS5.
The location of the set screw is shown in the diagram below:
Captive
Fore/Aft Tension