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Patent 1216357 Summary

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Claims and Abstract availability

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(12) Patent: (11) CA 1216357
(21) Application Number: 1216357
(54) English Title: STEREOSCOPIC TELEVISION SYSTEM
(54) French Title: SYSTEME DE TELEVISION STEREOSCOPIQUE
Status: Term Expired - Post Grant
Bibliographic Data
(51) International Patent Classification (IPC):
(72) Inventors :
  • LIPTON, LENNY (United States of America)
  • STARKS, MICHAEL R. (United States of America)
  • STEWART, JAMES D. (United States of America)
(73) Owners :
  • STEREOGRAPHICS CORPORATION
(71) Applicants :
(74) Agent: OYEN WIGGS GREEN & MUTALA LLP
(74) Associate agent:
(45) Issued: 1987-01-06
(22) Filed Date: 1984-01-17
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
459,174 (United States of America) 1983-01-19

Abstracts

English Abstract


Abstract
Stereoscopic Television System
An improved stereoscopic television system is
disclosed, having a great deal of compatibility with
the existing commercial television infrastructure.
Flicker is eliminated while preserving the existing
bandwidth allowing the stereoscopic video signals to
be handled with conventional apparatus such as video
tape recorders, video disks, or broadcast equipment.
In the present invention the number of fields per
second is twice that of he standard field rate. When
displayed on an unmodified receiver or monitor, each
subfield image appears to be anamorphically compressed
in the vertical direction by a factor of two. A
blanking area and/or vertical sync pulse separates the
two subfields.


Claims

Note: Claims are shown in the official language in which they were submitted.


THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A television system having means for providing
standard video fields of standard duration but with each
field comprising a first subfield in its upper half with
the image therein vertically compressed and a second sub-
field in its lower half with the image therein vertically
compressed, said first and second subfields being separated
by a blanking area including a vertical sync pulse.
2. A television system as in claim 1 wherein each
pair of video subfields comprises a stereoscopic pair of
images.
3. A television system as in claim 1 wherein said
upper subfield comprises the left side of a stereoscopic
image pair and said lower subfield comprises the right side
of the stereoscopic image pair.
4. A television system as in claim 1 wherein said
upper subfield comprises the right side of a stereoscopic
image pair and said lower subfield comprises the left side
of the stereoscopic image pair.
5. A television system as in claim 1 including means
for vertically compressing each subfield by a factor of
two.
6. A television system having means for providing
standard video fields of standard duration equal to
(1/vertical deflection frequency) but with each field
comprising a first vertically compressed subfield in its
upper half and a second vertically compressed subfield in
its lower half, said first and second subfields being
separated by a vertical sync pulse.
7. A television system as in claim 6 wherein said
subfields are additionally separated by a blanking area.

36
8. A television system as in claim 6 wherein each
pair of video subfields comprises a stereoscopic pair of
images.
9. A television system as in claim 6 wherein said
upper subfield comprises the left side of a stereoscopic
image pair and said lower subfield comprises the right
side of the stereoscopic image pair.
10. A television system as in claim 6 wherein said
upper subfield comprises the right side of a stereoscopic
image pair and said lower subfield comprises the left side
of the stereoscopic image pair.
11. A television system as in claim 6 including means
for vertically compressing each subfield by a factor of
two.
12. A stereoscopic television system for providing
standard video frames, each frame having a pair of inter-
laced fields, of 1/60th a second each, comprising: means
for providing a pair of vertically compressed stereoscopic
subfields within each field, one subfield being provided by
approximately the first half of the raster scan lines and
the second subfield being provided by approximately the
second half of the raster scan lines, successive pairs of
first subfields interlaced to form video frames constitu-
ting the first of a stereo pair, successive pairs of second
subfields interlaced to form video frames constituting the
second of a stereo pair; and wherein each of said subfields
is separated by a vertical sync pulse.
13. A stereoscopic television system as in claim 12
wherein each of said subfields is separated by a blanking
area.
14. A stereoscopic television system as in claim 12
wherein each of said subfields is separated by a blanking
area and a vertical sync pulse.

37
15. A stereoscopic television system as in claim 12
including means for vertically compressing each subfield by
a factor of two.
16. A stereoscopic television system for providing
video fields of standard time duration with one vertically
compressed stereoscopic image forming a first subfield
within the upper half of each field and the other vertical-
ly compressed stereoscopic image forming a second subfield
within the lower half of each field, the subfields being
separated by a blanking area and vertical sync pulse,
comprising:
a first video camera for creating one of the two
vertically compressed stereoscopic images for the
first subfield, said first camera having means for
operating at twice the normal vertical frequency
rate;
a second video camera for creating the other of the
two vertically compressed stereoscopic images for
the second subfield, said second camera having
means for operating at twice the normal vertical
frequency rate;
means for switching between each of said cameras after
each subfield; and
means for providing a blanking area and vertical sync
pulse between subfields.
17. A stereoscopic television generation system for
providing video fields each having a period defined as
(1/vertical frequency rate) with one stereoscopic image
forming a first vertically compressed subfield within the
upper half of each field and the other stereoscopic image
forming a second vertically compressed subfield within the
lower half of each field, the subfields being separated by
a blanking area and/or vertical sync pulse, comprising:

38
a first video source for creating one of the two
vertically compressed stereoscopic images for the
first subfield, said first video source having
means for operating at twice the normal vertical
frequency rate;
a second video source for creating the other of the
two vertically compressed stereoscopic images for
the second subfield, said video source having means
for operating at twice the normal frequency rate;
means for switching between each of said video sources
after each subfield; and
means for providing a blanking area and/or vertical
sync pulse between subfields.
18. A stereoscopic television generation system for
providing standard video fields of standard duration but
with one stereoscopic image forming a vertically compressed
first subfield within the upper half of each field and the
other stereoscopic image forming a second vertically
compressed subfield within the lower half of each field,
the subfields being separated by a blanking area and/or
vertical sync pulse, comprising:
a first video source for providing one of the two
stereoscopic images for the first subfield;
a second video source for providing the other of the
two stereoscopic images for the second subfield;
means for switching between each of said video sources
after each subfield;
means for providing a blanking area and/or vertical
sync pulse between subfields; and
means for vertically compressing each subfield by a
factor of two.

39
19. The stereoscopic television generation system of
claim 18 wherein said compressing means comprises a digital
effects device.
20. The stereoscopic television generation system of
claim 18 wherein said first and second video sources each
comprises a video camera.
21. A stereoscopic television system for providing
video fields of standard duration but with one stereoscopic
image forming a first subfield within the upper half of
each field and the other stereoscopic image forming a
second subfield within the lower half of each field, the
subfields being separated by a blanking area and/or verti-
cal sync pulse, comprising:
a television raster scan image device;
means for alternately providing the first of a pair of
vertically compressed video images on one-half of
said television imaging device and the second of a
pair of vertically compressed video images on the
other half of said television imaging device;
means for centering the television imaging device
raster on the first video image when it is provided
and for centering the raster on the second video
image when it is provided, whereby the resulting
output from said image device is alternating video
subfields of said first and second vertically
compressed images; and
wherein the vertical raster scan rate of said
television imaging device is twice that of a
standard television imaging device.
22. A stereoscopic television generation system as in
claim 21 including means for adding a blanking area and/or
vertical sync pulse between the respective subfields.

23. A stereoscopic television generation system as in
claim 21 wherein said television imaging device is a tele-
vision pick-up tube.
24. A stereoscopic television system for providing
video fields of standard duration with one stereoscopic
image forming a first vertically compressed subfield within
the upper half of each field and the other stereoscopic
image forming a second subfield within the lower half of
each field, comprising:
an unmodified television raster scan imaging device;
an optical system for taking stereoscopic pairs of
images through side-by-side left and right lenses
and including means for converting the side-by-side
images to over-and-under vertically compressed
subfield images for delivery to said imaging
device; and
means for inserting a blanking area vertically
compressed and sync pulse between the over-and-
under vertically compressed subfield images.
25. A stereoscopic television system as in claim 24
wherein said optical system comprises and over and under
lens system.
26. A stereoscopic television system as in claim 24
wherein said optical system comprises an optical fiber
delivery system.
27. A stereoscopic television system as in claim 26
wherein said optical fiber delivery system comprises a
first optical fiber bundle connected from one of the
side-by-side lenses to the upper half of said television
imaging device and a second optical fiber bundle connected
- Page 6 of Claims -

41
from the other side-by-side lens to the lower half of the
said television imaging device.
28. A stereoscopic television generation system as in
claim 27 wherein the images through said first and second
optical fiber bundles are anamorphically compressed in the
vertical direction by a factor of two by altering the
spacing of the optical fiber bundles.
29. A stereoscopic television system for providing
video fields of standard duration, but with one stereosco-
pic image forming a first subfield compressed vertically
within the upper half of each field and the other stereo-
scopic image forming a second subfield within the lower
half of each field, comprising:
a programmed digital computer for generating the
respective vertically compressed images forming
said first and second subfields, said subfields
being anamorphosed in the vertical direction; and
means for inserting a blanking area/vertical sync
pulse between said subfields.
30. A stereoscopic television display system for dis-
playing incoming video fields of standard duration, with
each field having one stereoscopic image forming a first
vertically compressed subfield within the upper half of
each field and the other stereoscopic image forming a
second vertically compressed subfield within the lower half
of each field, the subfields being separated by a blanking
area and vertical sync pulse, comprising means for doubling
the normal vertical sync rate of said display system so
that the vertically compressed subfields appear as indivi-
dual, normal sized uncompressed fields.
31. A stereoscopic television display system for dis-
playing incoming video fields of standard duration, but
with each such field having one stereoscopic image forming

42
an anamorphosed first subfield within the upper half of
each field and the other stereoscopic image forming an
anamorphosed second subfield within the lower half of each
field, the subfields being separated by a blanking area
and/or vertical sync pulse, comprising: optical means for
preventing one eye of the viewer from seeing the upper
displayed subfield and preventing the other eye from seeing
the lower displayed subfield; said optical means including
means to deanamorphose each displayed subfield.
32. A stereoscopic television display system as in
claim 31 wherein said television display system includes a
cathode ray tube display and said optical means comprises:
(a) a first polarizer placed on said cathode ray tube
display over the area of the displayed upper
subfield;
(b) a second polarizer placed on said cathode ray
tube display over the area of the displayed lower
subfield, the axes of polarization of said first
and second polarizers being generally orthogonal
to each other; and
(c) side-by-side binocular viewing elements, one
viewing element containing a third polarizer
having an axis of polarization generally parallel
to that of said first polarizer, and the other
viewing element containing a fourth polarizer
having an axis of polarization generally parallel
to that of said second sheet polarizer.
33. A stereoscopic television display system as in
claim 31 wherein said deanamorphose means comprises a
cylindrical lense.
34. A stereoscopic television display system as in
claim 32 wherein each of said viewing elements includes a
prism to align the axes of the respective subfield images.

43
35. A stereoscopic television projection display
system for displaying incoming video fields of standard
duration with one stereoscopic image forming a first
anamorphosed subfield within one half of each field and the
other stereoscopic image forming a second anamorphosed
subfield witih the other half of each field, the subfields
being separated by a blanking area and/or vertical sync
pulse, comprising:
a plurality of raster scan projectors for projecting
primary colour images in superimposition onto a
screen;
means for optically isolating the two projected sub-
fields from each of said raster scan projectors;
means for polarizing the respective subfield images
with polarizers whose axes of polarization are
orthogonally oriented;
means for superimposing the respective projected
polarized subfields onto a screen with the proper
stereoscopic parallax; and
means associated with each of the plurality of raster
scan projectors to deanamorphose the respective
subfield pairs.
36. A stereoscopic television projection display
system as in claim 35 wherein said isolating means compri-
ses means for locating each of said polarizing means and
each of said superimposing means at a sufficient distance
from said projectors.
37. A stereoscopic television projection display
system as in claim 35 wherin said isolating means comprises
a double curved reflector with the interface of the two
reflectors being aligned to coincide with the projected
blanking area and/or vertical subfield.

44
38. A stereoscoic television projection display sys-
tem as in claim 35 wherein said first and second subfields
are arranged in an over-and-under format.
39. A stereoscopic video assist viewfinder for a
stereoscopic movie camera comprising:
a conventional stereoscopic movie camera with over and
under stereoscopic lenses;
means for diverting the over-and-under image from the
camera film to a viewing screen;
a television monitor;
a video camera for transmitting the over-and-under
image on said viewing screen to said television
monitor in the form of over-and-under subfields
within a single field of standard duration;
means for inserting a blanking area and video sync
pulse between the resulting over-and-under sub-
fields; and
means for enabling a viewer to stereoscopically view
the images displayed on said monitor.
40. A viewfinder as in claim 39 wherein said enabling
means comprises means for operating said monitor at twice
the normal vertical sync rate, and occluding means synchro-
nized with the fields on said monitor to alternately block
the viewer's left and right eyes.
41. A television system having means for providing
standard video fields of standard duration but with each
field comprising a first vertically compressed subfield in
one-half of a standard field and a second vertically
compressed subfield in the other half of a standard field,
said first and second subfields being separated by a
blanking area and vertical sync pulse.

42. A television transmission system as in claim 41
wherein said first subfield is provided in the left side
and the second subfield in the right side of the standard
video field.

Description

Note: Descriptions are shown in the official language in which they were submitted.


3~'~
,
~ n
Stereoscopic Television Systeln
. . _
Technical Field
This invention provides a new stereoscopic imaging
system. Specifically, an improved stereoscopic tele-
vision system is disclosed, having a great deal of
compatability with the existing commercial television
infrastructure. Compared with the prior art employing
sequential presentation of right-left images, in what
is sometimes called the eclipse or occlusion system, we
have eliminated flicker whilst preserving the existing
bandwidth allowing our stereoscopic video signals to be
handled with conventional apparatus such as video tape
recorders, video discs, or broadcast equipment.
Background Art
Present systems using alternate field enooding
with individual occluding selection devices is hampered
primarily by severe image flicker. ~andwidth restric-
tion prevent doubling the number of fields needed byeach eye for good image quality. A full discussion of
the subject is given in FO~NDATIONS OF THE STER20SCOPIC
CINEMA (Lipton, Van Nostrand Reinhold, New York, June,
1982).
,~
~i~ '

--2--
S~lmmary of the_Inve t _n
The present invention is based upon prior ~rt
employing switching techniques for displaying seq~en-
tially presented right and left image pairs, with
certain important and unique differences. In the
usual technique put into practice by Megatek, Panasonic
(Matshushita) and Honeywell, video fields are alter-
nately encoded with right or left information resulting
in a reduction of fields which reach each eye to half
the usual field rate. This results in intolerable
flicker. In the present invention the number of fields
per second is doubled by various means. In one tech-
nique we double the vertical scanning rate, thereby
producing 120 fields instead of 60 fields per second.
Thus the number of fields is doubled whilst the number
of lines per field is halved.
When displayed on a usual receiver or monitor,
each image will appear to be anamorphically compressed
in the vertical direction by a factor of two. Two
such images, the right and left fields, above and
below, will be seen on the unmodified monitor. In
the preferred embodiment a vertical sync pulse signal
is added to a blanking area between the two subfields.
- These left and right fields, in this format, shall be
referred to herein as left and right subfields. A sync
pulse signal is added between the upper and lower
images, or only a blanking area is provided, with no
vertical sync signal between the two subfields. When
displayed on a suitably modified monitor the two images
are displayed in sequence. The monitor must also have
the vertical controlling picture circuit adjusted to
double deflection, e.g., double vertical sync frequency
in order to display an image of proper proportions. An
electronically unmodified monitor or receiver may be
adapted for three-dimensional viewing with a stereoscope

3~
-3-
hood disclosed herein. Projection o~ stereoscopic
images are also possible usinq apparatus disclosed
herein.
The camera may take the form oE a single camera
with an image forming system capable of producing the
two perspective viewpoints imaged above and below.
By simply adding the appropriate
sub-field blanking area and/or vertical pulse between
the two images so formed by such optics, the electronic
requirements for display are fulfilled.
On the other hand, the image source may be a
two camera ensemble mounted on a single base or on
separate bases, so adjusted to produce the necessary
stereoscopic pair of images. These cameras are then
adjusted to produce 131.25 line resolution images each,
with fields externally or internally synchronized by a
sync generator producing 120 Hz vertical drive pulses.
Thus, in the time that a single planar image made
up of two 262.5 line fields would be produced, these
two cameras produce four 131.25 lines per field.
Therefore, 120 fields are produced in a second, half of
them for the right perspective viewpoint and half for
the left. These fields are then transmitted and
received in the follo~ing manner: right-left-right-left.
This sequence of four fields constitutes one stereoscopic
image unit or image pair. These fields may also be
presented in the following manner: right--right--left--
left.
Note that the band~idth requirement remains the
same for our system as for the television system
commerci~lly employed. Thus transmission of such a
signal by closed circuit, through the air broadcast, or
via cable may also be achieved. ~oreover, the e~isting
video tape and video disc formats are also capable of

recordin~ and playing back such signals without any
modification.
Although the explanations given herein are in
terms of the usual NTSC system used in North America
and other places, using a total number of approximately
500 lines per picture, with 30 pictures per second,
each picture made up of two fields with approximately
250 lines per field, we do not limit ourselves to this
specfic system. Other areas of the world use different
field rates and the total number of lines per field
may be different. High resolution systems have been
developed which use a greater number of horizontal
lines. But these systems may all be adapted to the
stereoscopic format described within this disclosure,
by the means given herein.
Accordingly it is an object of this invention
to provide an improved stereoscopic television system
with a bright and flickerless display.
A further object of this invention is to provide
a stereoscopic television receiver or monitor which is
similar to the existing receiver or moni-tor apparatus
with regard to substantial portions of existing elec-
tronic circuits and display devices.
Another object of this invention is to provide
a television system which may be used for closed
circuit applications such as on-the-job industrial
applications, medical imaging during procedures, or for
video assist viewfinding in conjunction with motion
picture cinematography, said system providing images
which are flickerless, sharp, bright and in color if
so desired.
A still further object of this invention is to
provide a stereoscopic television system which is
highly compatible with the existing commercial tele-
vision broadcast infrastructure for through the air orcable transmission.

--5--
Yet another object of this invention is to pro-
vide stereoscopic encoding using existing or fut~re
video, tape or disc formats desiyned to function within
the existing transmission bandwidth.
Another object of this invention is to increase
or double the existing field rate of the display
device in order to effectively double the field rate
for each eye, and to thereby eliminate flicker by
raising the number of fields per eye per unit of
time above the critical fusion frequency threshold.
Another object of this invention is to double
the existing field rate at the CRT or similar display
device in such a way as to eliminate spurious temporal
parallax effects.
A further object of the present invention is to
provide a display device suitable for three dimensional
computer graphics, simulator displays, medical imaging
like CAT scan, ultra sound, or stereo X-ray and for
video games.
And another object of the present invention is
to provid2 a stereoscopic television receiver or
monitor which may playback conventional planar trans-
missions.
Still another object o the present invention is
to enable multiple viewers to see different programs
on a single display device. Occluding or polarizing
glasses could be so adjusted to display but one of
two programs.
Yet another object of the present invention is
to allow for single camera operation using optics
similar to those employed in the past for motion
picture and still stereoscopic photography on a
single frame of film.

~ 3~t)
--6--
Another object o~ the present invention is to
allow for the use of a Eiber optic conve~tor designed
to allow existing photographic objectives to inter-
face ~ith a video camera to provide the necessary
over-and-under images to be formed on the light
sensitive surface after having been imaged through
the appropriate horizontally displaced perspective
points of view.
Another object of the present invention is to
provide a low voltage powered source for electro-optical
occluding spectacles which steps up this safe voltage
to a useful higher voltage value.
A further object of the present invention is to
provide relatively simple and economical means for
optical projection of stereoscopic television images
so that they may be viewed by large numbers of persons
wearing individual selection device of passive design.
Other objects of the present invention are
described herein and we do not mean to limit ourselves
by those set forth above.
Brief Description of the Drawings
Fig. 1 shows right and left image subfields as
they would be displayed on a conventional unmodified
video monitor, with the right subfield above and the
left below, and witn the subfield vertical blanking
area and/or vertical sync pulse signal added between
the two.
Fig~ 2A shows a schematic set-up of the dual
ensemble stereocamera, using an external sync generator,
feeding right and left images to a display device to be
viewed with the aid of an individual selection device.
Fig. 2B shows a schematic set up of the dual
ensemble stereocamera using a digital effects box
feeding right and left images to a display device
.

-7-
to be viewed with the aid o~ an individual selection
device.
Fig. 2C is a block diagram of the electronics
associated with the arrangement of Fig. 2A.
Fig. 2D is the schematic oE the electronics of
Fig. 2C.
Fig. 3A is a schema-tic diagram of the sync pulse
inserter used to process compatible video signals
for stereoscopic display.
Fig. 3B is a schematic diagram of the sync
pulse inserter shown in Fig. 3A.
Fig. 3C is a plot of the voltage as a function
of time for the vertical interval produced by the
sync pulse inserter shown in Fig. 3B.
Fig. 3D is a representation of the video signal
input to the apparatus of Fig. 3B.
Fig. 3E is a representation of the video signal
after being processed by the sync pulse insertion
circuit of Fig. 3B.
Fig. 4 shows a schematic view of the apparatus
needed to image the over-and-under views as shown in
Fig. 1 with a single over-and-under camera lens as
employed for motion picture cinematography.
Fig. 5 shows the schematic layout of a fiber
optic over-and-under imaging unit enabling adaptation
- of conventional paired optics to produce the desired
over-and-under disposition of stereopairs.
Fig. 6A is a diagrammatic view of a dual lens
stereoscopic objective mounted on a ~.elevision camera.
Fig. 6B shows the raster rotated through 90
degrees to be used in conjunction with the optic shown
in 6A.
Fig. 6C is a schematic presentation of analog-
to-digital-to-analog converter used to interface the

t~f~
optic and associated system shown in GA with a normal
horizontally dis~osed raster.
Fig. 7 is a schematic diagram of the electronics
associated with the single camera technique for photo-
graphing and displaying stereoscopic video irnages asdisclosed herein.
Fig~ 8A shows a diagrammatic presentation of a
video assist viewfinder as might be employed for the
production o theatrical films allowing for the dis-
play of stereoscopic images in real time during photo-
graphy.
Fig. 8B shows a schematic view of a conventional
video camera looking at the ground glass screen as
depicted in Fig. 8A.
Fig. 9A is a cross section of a video projector
converted to project three-dimensional images according
to the format disclosed herein.
Fig. 9s is a cross section of a specially designed
projector to display t'nree-dimensional images according
to the format disclosed herein.
Fig. 10 is a schematic diagram of the electronics
associated with the recentration corrector convergence
setting device described herein.
Fig. 11 is a schematic diagram of the electronics
system used for powering and synchronizing electro-
optical spectacles using low voltage stepped up to a
higher voltage at the spectacles.
Fig. 12A shows the design of a stereoscope hood
to be used to view three-dimensional images with the
above-below format.
Fig. 12B is a cross-sectional view o the optical
elements employed in the stereoscope illustrated in
Fig. 12A.
Fig. 13 is a diagramrnatic representation of the
skittering process wherein the raster position is

3~1~
_9_
alterecl to provide par~llax in~ormation hy means
of a sin~le camera and dual lens.
Detailed Descriptiol1 of the Drawings
This stereoscopic television system encodes right
and left images which are displayed in the manner
illustrated in Fig. 1 when played back on a standard
receiver or monitor. The right image field 3 is shown
to be above the left image field 4, but the teaching of
the disclosure is in no way altered if left 4 is placed
above and right 3 below. The reader will note that the
fields are vertically compressed or anamorphosed by a
factor of two. The blanking region 1 between fields 3
and 4 may provide sync pulse information in accordance
with techniques to be discussed later.
With reference to Fig. 2A, we see the arrangement
of double camera ensemble and some of the electronics
associated with stereoscopic videography and viewing
of the format described above and illustrated in
Fig. 1. This dual camera rig uses video cameras 7 and
9 for imaging left and right stereoscopic fields with
le~t and right objectives 6 and ~. Cameras are mounted
on base 10 which may make provision for varying the
interaxial separation between the cameras. External
sync generator 11 and alternative subfield switch 11',
synchronizes the camera subfields and can provide power
for electro-optical occluding spectacles 12 which are
used to view the image 13 on cathode ray tube (CRT) 14.
The elements 12' and 12" of the spectacles may use any
form of occluding ccheme, but in all likelihood this
will be electro-optical rather than mechano-optical.
In some ap~lications, such as arcade games, mechano-
optical selection devices may have advantages.
Although a CRT is shown as the display device through-
oùt this disclosure, we do not limit ourselves to

3~;~
-- 1 o--
this means since o~her dis2lay techniques already
- in existence or under developrnent will be usable so
long as they have suitable characteristics to display
and refresh at an appropriate rate on a plane surface
with images of the desired characteristics as set
forth ~Jithin this disclosure.
A more detailed discussion of the electronic
systems involved in this camera and display setup will
be given later in this disclosure in conjunction with
Fig. 3A.
Since the right and left images are scanned with
half the number of horizontal lines (at twice the
usual rate) each image will fit into half the space
vertically.
Fig. 2A illustrates an analog scheme for inter- -
locking t~o video cameras to produce the desired format.
The cameras must have suitable characteristics and must
be accordingly modified in order to operate at twice
the vertical frequency. The cameras fields are
outputed one after the other and separated by a suit-
able vertical blanking interval to produce the final
video output suitable for viewing ~Jith display device
14.
Fig. 2C is a block diagram of the sync generator
11 and s-~itch 11 used in the arrangement of Fig. 2A.
Fig. 2D is the schematic diagram of the same sync
generator 11 and switch 11 .
The left and right video cameras 7 and 9 are modi-
fied to a higher vertical scan frequency ~hile retain-
ing the normal horizontal rate. The sync generator 11is built around a standard sync generator IC such as
~ational Semiconductor IMM5321N.
Crystal oscillator and divider 200 provides the
cloc~ signal to run the sync generator 201. This chip
~rovides horizontal vertical and composite sync to

NTSC standards. The horizontal drive is buffered to
the cameras by buffers 20~A & 206C. ~rhe ver~ical drive
resets the counter ~02 which then co~1nts horizontal
lines to 1/2 lines per field. The output of counter
202 triggers one-shot 203 to output a 3H wide pulse.
This pulse is "OR"ed by gate 204 with the vertical
drive of 201 and buffered by 206B & 206D to the cameras.
The vertical drive SETS and the output of one-shot 203
RESETS a "D" FlipFlop 205 producing a square wave 10 corresponding to the subfield selected. This square-
wave drives analog switch 207 selecting the output of
the required video camera. At summer-buffer 208 the
composite sync -from sync generator 201 is summed to the
video from switch 207 producing composite video.
Fig. 2s on the other hand, illustrates digital
means to accomplish the same end. External standard
sync generator 2 interlocks cameras 7 and 9, and
digital effects box 5 which compresses the images
produced by cameras 7 and 9 and places them above and
below each other with a suitable blan~ing interval
interposed between the two, in accordance with the
format described herein and shown in Fig. 1.
The reader will understand that Digital Video
Effects boxes are manufactured by the Nippon Electric
Corporation of Tokyo, Japan and others. These boxes
receive in any format images and compartmentalize the
image over limited areas. Therefore, images having the
normal width but only one-half the normal height with
vertical compression can be produced easily. It will
be understood that utilizing such equipment one need
only operate the existent controls to produce the
effect generated here. The beneficial portion of the
use of such equipment is that the image scheme here is
produced without any wiring and/or internal electronic

--12-
changes whatsoever. ~lowever, such equipment is very
expensive.
Thus any two video cameras may be used in a dual
camera stereoscopic ensemble, without electronic
modification to said cameras, providing the video
output of the two cameras is proceised as shown in Fig.
2s using digital imaging techniques. We have used this
technique to process leEt and right rolls of video
- tape, photographed by appropriate left and riyht
cameras. Such video kapes are run on recorders in
interlock, and the video signals of these recorders are
processed by a digital effects box and dubbed onto a
stereoscopic master tape for playback in accordance
with the above and below format.
The disposition of left and right image fields
disclosed herein neatly interfaces with filmmaking
schemes for imaging left and right images onto a single
piece of film. Fig. 4 shows a schematic view using a
single video camera with an over and under optic 15 the
ty~e of which was originally designed by Bernier and is
disclosed in his U.S. Patent No. 3,531,191. The
images as shown in Fig. 1 will be formed on the face-
plate of the pickup tube of video camera 16. The
necessary subfield blanking area and/or sync pulses can
25 be inserted between the upper and lower images so that
a three-dimensional image may be viewed in accordance
with our teachings.
As an alternative to ~he above, we disclose with
the aid of Fig. 5 a technique using a fiber optic
converter to be employed in conjunction with a video
camera. Pickup tube 18 has its face plate 19 in
immediate and intimate juxtaposition with twin fiber
optic devices 17 and 20. Images are formed by lenses
21 and 22, a matched pair of objectives. These provide
the necessary two perspective points of view for a

--13-
stereoscopic pair. The images are ~ormed on ~he
sur~aces of the Eiber optic bundles 17a and 20a and
thence are carried back to face plate 19 so disposed as
given earlier in this disclosure to be over and under
as shown in Fig. 1. Thus, a variety of optics may be
employed with a single video camera. ~loreover, the
images need to be anamorphically compressed in the
vertical direction by a factor of two, and as is well
known in the art, this type of compression has been
achieved by altering the spacing of the fiber optic
bundle in the desired direction of compression. Thus,
the images may be appropriately disposed on the face
plate of the video camera tube and their compression
altered by the same fiber optic bundles.
r~e will now describe a stereoscopic video assist
viewfinder for the professional motion picture industry.
Fig. 8A and Fig. 8B illustrate the embodiment.
Video camera 23 with an objective lense 24 of
conventional design 24 looks through semi-silvered
mirror 25 at ground glass image 29 reflected from the
motion picture camera moving mirror 26, a portion of
the camera's reflex viewing system. Over and under
objective 27 forms an image onto film 35 when mirror 26
is swung out of the way, or onto ground glass screen 29
for reflex viewing as formed by eye piece 30 and seen
by eye 31.
- Given the present state of the art, cinema-
tographers will see two images on the ground glass
screen of the inder and not a single stereoscopic
image as is desirable. Therefore, a video assist
three-dimensional system as described here will
greatly facilitate production by allowing technicians
to preview desired stereoscopic effects at the time of
production, rather than during projection of dailies.

The over anc~l under image as formed on ground
glass screen 29, consisting oE right and leEt fields
32 and 34, respectively, are photographed with video
eamera 23 with subfield blanking area and/or sync pulse
33 added to the signal by electronics 11 which also
can synchronize the eleetro-optical spectacles to the
field rate as displayed on the screen 13 of CRT 14.
Thus variations in the lens controls, such as con-
vergence or interaxial setting, can be instantly viewed
an~ evaluated on screen 13, resulting in a savings of
time and money for the production erew. Viewing may be
aeeomplished in monochrome or color, and images may be
taped for study. Existing video assist cameras may be
readily adapted to this technology. They already allow
for planar viewing oE images, and our teehnology would
allow for three-dimensional viewing using these already
eommonplaee instruments.
The system of viewing three-dimensional images
through eamera viewfinders may also be employed using
two video camera photography which is aecomplished with
- double system cameras, which are usuall~ Ramsdell of
"L" type eonfiguration rigs. The images are then
eombined in aeeordanee with that portion of this
diselosure illustrated by Fig. 2~ or Fig. 2B.
When the glasses are removed the left and right
images are seen superimposed on eaeh other, providing a
perfeet opportunity to eorreet for eentration errors
whieh often erop up even in well engineered dual eamera
rigs. In addition, eonvergence may he set by means of
this technique.
It should also be mentioned that this teehnology
ean be used to help view film stereoseopieally during
the editorial process. The same sort of arrangement
shown in Fig. 8B might also be employed to photograph,

-l5-
with a video calnerc1, imaqes on an e(1iting machine
screen to be viewed stereoscopically.
As we have described earlier, stereoscopic optics
like those designed for motion picture work, for
imaging the two perspective viewpoints over-and-under,
are directl~ applicable to the present three-dimensional
video format. However, such optics are costly and
complex, because of the need to take the two horizon-
tally displaced viewpoints and move their resultant
images to relative vertical displacement. ~ther
types of optics, less costly and complex, have been
developed. One type, ofEered Eor sale by Bolex*in
the early fiEties (described by l~lillet, 1952, Some
Geometrical Conditions for Depth Effect in Motion
Picture, Journal of the SMPTE, 59:517-23), followed a
design in common use by that time. As shown in Fig. 6A
twin optics 37 and 38 are placed side-by-side and
obtain their necessary interaxial separation by means
of reflecting surfaces 42 and 43 and 39 and 40. The
optical system is less complex than over-and-under
systems. Side-by-side images are formed, in our
application, on faceplate 19 of pickup tube 18 of
video camera 36. Thus the dual optic 41 allows a
single video camera to become a source of stereo-
scopic in~ormation. However, the images are placedside-by-side, not over-and-under as would be in
accordance with the needs of the present teaching.
- But the present teaching doesn't have to be limited
to over-and-under imaging, since means can be pro-
vided to adapt side-by-side imaging to our needs.
If the camera raster were rotated through 90
degrees to provide the vertical orientation of picture
line elements, as shown in Fig. 6B, the intersection
of the two images and the blanXing area used for the
sync pulse ~ould coincide. Thus the sync pulse could
* Trade mark

3~
-16-
be added as described elsewhere in this disclosure.
Next the monitor CRrr must use a vertical raster in
order to be compatible with the method of photography.
The vertical orientation of the raster may be
obtained by a rotated camera pick up tube yolk and
monitor CRT, or by physically turning the equipment
on its side.
Other means may also be provided to enable us to
employ side-by-side optics, as shown in Fig. 6C. Lens
41 images the stereopair side-by-side on the faceplate
of camera 36 as described above and shown in Fig. 6A.
Next the analog video signal from 36 is processed by
analog to digital to analog converter 48 which in
effect rotates the picture line elements back to hori-
zontal alignment. Although the yolk of pickup tube 18of camera 36 may be oriented through 90 degrees in
order to produce the necessary vertical raster, the
analog-digital analog unit, using well-known techniques,
re-orients the raster and creates the format as shown
in Fig. 1, so that it may be displayed on unmodified
CRT 49 with a horizontal raster on screen 50.
Such images processed by 48 would be completely
- compatible with images produced by the camera ensemble
illustrated in Fig. 2A Those versed in the art will
understand that howsoever images are disposed on the
camera faceplate by stereoscopic optics, digital
techniques may be used to produce the above and below
~ormat illustrated in Fig. 1 and described throughout
this disclosure.
A purely optical solution to the problem of image
orientation and alignment with the raster can also
be found. Dewhurst (Introduction to 3-D, Macl'lillan
Co., 1954) describes a number of schemes for orienting
or rotating images for motion picture stereoscopy
using mirror or prism systems. It is possible to

:L~
-17-
produce two ;mages sic1e-by-side, but each o~ which
is rotated through 90 deyrees in the same direction.
Such a pair of images would automatically suppl~ the
necessary image alignment with the raster so that
the blanking area would lie between the images. The
raster is vertically oriented to accommodate the dual
images which have a vertical boundary between them.
The important thing here is that optical means can
be provided for rotating the two images in the same
direction and through 90 degrees.
The video output of a camera with such an optic
mounted can be displayed directly on a monitor which
has the usual horizontal raster.
For many applications the use of relatively small
CRT displays, commonly up to 26 inches in diagonal,
using active glasses with elements occluding in synchro-
nization with the alternately presented right and left
fields, will provide an adequate means for several
individuals to view stereoscopic television images.
However, there may be occasions when it is preferable
- to show such images to large groups of people on larger
screens. In such a case our system offers the viable
- option of projected video images to be viewed stereo-
scopically by means of passive glasses employing tne
technique of image selection by polarization. Such a
technique, using spectacles with sheet polarizes
aligned to correspond with the orientation or projection
lens sheet polarizers, is well-known art and its modern
form was disclosed by Land in U.S. Patent No. 2,099,694.
First, we will describe a technique for conversion
of existing video projection units to stereoscopic
projection lenses each projecting an additive color
primary in superimposition onto a high gain screen.
For the sake of simplicity we will show but a single
necessary image alignment with the ras~er so that the

blanking area would lie bet~eel1 the images. The raster
- is vertically oriented to accomrnodate the dual images
which have a vertical houndary between them. The
important thing here is that optical means can be
provided for rotating the two images in the same
direction and through 90 degrees.
The video output of a camera with such an optic
mounted can be displayed directly on a monitor which
has the usual horizontal raster.
For many applications the use of relatively small
CRT displays, commonly up to 26 inches in diagonal,
using active glasses with active elements occluding in
synchronization with the alternately presented right
and left fields, will provide an adequate means for
several individuals to view stereoscopic television
images. ~o~ever, there may be occasions when it is
preferable to show such images to large groups of
people of larger screens. In such a case our system
offers the viable option of projected video images to
be viewed stereoscopically by means of passive glasses
employing the technique of image selection by polari-
zation. Such a technique, using spectacles with sheet
polarizersaligned to correspond with the orientation of
projection len. sheet polarizers, is well-known art and
its modern form was disclosed by Land in U.S. Patent
No. 2,099,694.
First, we will describe a technique for conversion
of existing video projection units to stereoscopic
projection lenses each projecting an additive color
primary in superimposition onto a high gain screen.
For the sa~e OL simplicity we will show but a single
projection lens as depicted in Fig. 9A.
Typically a small and bright C~T 52 is at the
focal point of spherically curved mirror 51 and
light is projected onto screen 57 after having passed

$;~
_19_
through correction plate 53. ~1e add means for super-
imposing the left and right irnage Eields and polari~iny
each field. This is to be accomplishecl by an add-on
converter made up in part of sheet polarizers with
axis orthogonally oriented labeled 54 and 5~'. The
images are sufficiently separated when tney reach 54
and 54', so that they may be individually treated by
the add-on optical system. It should be noted that
sheet polarizers 54 and 5~' may be placed after prisms
55 and 55' or after anamorphic lenses 56 and 56', and
that the components shown here may well be reordered
and that such a repositioning in no way alters the in-
tention of this teaching.
Prisms 55 and S5' are chromatically corrected and
of such a dioptric power to cause the top and bottom or
over and under portions of the stereopair to be con-
verged on screen 57. Anamorphic elements 56 and 56'
are employed to restore the vertically compressed
images as shown in Fig. 1. However, such restoration
of the image to proper proportions may be accomplished
electronically so that the image formed on CRT 52 needs
no further restoration of shape.
Fig. 9B shows a three-dimensional projection tele-
vision optical system designed to be used with the
over-and-under format described herein. However, this
teaching may well be used for side-by-side disposed
images, or the like, and in no ~ay does this alter the
essence of the invention.
CRT 52 is at the focal points of dual mirror 60.
Mirror 60 is made up of two surfaces, joined at an
interface and separated b~ septum 59 which lies between
the mirror 60 and the CRT 52, and so aligned to exactly
coincide with the subfield blanking area. Its purpose
is to separate optically the upper and lower portions
of the stereopair. The optical centers o the two

-20-
halves oE mirror 6U are so adjusted to produce up and
down shifts in the upper and lower images to bring them
into essential coincidence on the screen as is neces-
sary ~or successful stereoscopic projection. It should
be noted that the two surEaces of 60 are essentially
identical, and that such a mirror, usually front
surfaced with metallic material, is generally the
surface of a sphere, or paraboloid of revolution. Thus
the individual upper and lower portions of the stereo-
scopic pair as shown in Fig. 1 are individually treatedand brought to focus on screen 57. Sheet polarizers
54 and 54' serve the same purpose as they did when
described above and as illustrated in Fig. 9A, and it
will be understood by those versed in the art that they
may be placed elsewhere in the optical system, such as
directly on the faceplate of CRT 52.
Anamorphic elements 58 and 58' are shown in
the optical system and are used to restore the image
to full vertical height if so required. Fig. 1, as
has been mentioned above, illustrates the possible
need for cylindrical optical elements, but it is
also conceivable that such shape restoration can be
- accomplished electronically, and it may also be un-
necessary to engage in such restoration since the
image may have no need of such restoration. It is
also possible to design the shape of mirror 60 so that
-- it deanamorphoses the image formed in the faceplate
of CRT 52. In any event, it should be obvious that
elements 58 and 58' may be left out of the system
and that their inclusion or exclusion in no way alters
the essential nature of this portion of our teaching.
~ onne, in U.S. Patent No. 3,858,0001, describes
a method for altering the axis of polarization of an
image displayed by a CRT, or similar display device, in
synchronization with the field rate, so that polarizing

3~
--21-
spectacles oE the type ~lsed for viewing motion picture
projection might be employed. ELectro-optical rnaterial
is difficult to manufacture in sizes larye enou~h to
cover such a display device, but the C~T's used for
projection are much smaller, making this approach more
practical.
Therefore, in addition to optical superimposition
of simultaneously projected above and below images, as
described above, alternate fields polarized orthogonally
may also be projected using electro-optical elements
switching in synchronization with the field rate.
We will now devote our attention to the electronic
systems of our stereoscopic television.
One basis for this invention is the use of a
vertical scanning frequency of twice the normal rate.
By doubling tne vertical scanning rate only, it is
possible to build a flickerless stereoscopic television
system which preserves the standard color subcarrier
frequency, the standard horizontal frequency, and the
bandwidth of the NTSC system.
Stereoscopic images can be generated with either
one or two camera systems. A bloc~ diagram of the two
camera system 7 and 9 is shown in Fig. 2A. A sync
generator 11 creates horizontal drive at the normal
frequency and vertical drive at twice the vertical
frequency. It supplies these signals to two suitably
modified video cameras. Each camera now scans a full
field consisting of 1/~ the number of horizontal lines
found in a standard video frame. The non-composite
video of the individual cameras is selected by subfield
video switch 11' at the end of each subfield with the
same ~amera output always selected ~irs~. This non-
composite video is then combined with a normal ~standard
vertical and horizontal rates) sync signal to create a
compatable composite video signal. The resultant

3~
-22-
signal ls shown in Pi~3. 3D. The result imaqe as seen
on a unmodified monitor is showr1 in Fig. 1.
One si~nificant improvement over previous video
systems is that the order of the subfields (left-
right or right-left) is always the same within all
fields eliminating any possible loss of synchronization
and phase with the viewer's occluding device. Hence,
it is not possible to mistakenly produce a pseudoscopic
image.
The display system of Fig. 2A utilizes a monitor
14 modified for a higher vertical rate. The incoming
compatible signal as shown in Fig. 3D is processed by
the sync pulse insertion circuit such as is shown in
Fig. 3B. This signal drives the monitor to sequen-
tially display two fully interlaced pairs of subfields
in the time of two standard fields. The same circuit
also provides the signal of Fig. 2A to synchronize and
phase the occluding glasses 12.
Thus, our stereoscopic television system utili~es
a unique synchronization system in order to eliminate
flicker with a minimal reduction of vertical resolu-
tion. The synchronization system offers only a small
departure from the NTSC video signal standards, allow-
ing the video to pass through the existing television
infrastructure with only minor processing.
The video signal used in our stereoscopic tele-
vision system is the same as defined by EIA proposed
standard RS-170A with the following exception: As
shown in Fig. 3C, each of the t~o fields, marked Field
1 and Field 2, in the RS-170A system are subdivided
into two subfields, giving a total of four subfields,
subfields 1 and 2 forming field 1, and subfields 3
and 4 forming field 2. Each pair of subfields are
separated by a vertical interval identical to the
interval presently used in the RS-170A system. The two

,3~
-~3-
additlonal vertical intervals are positioned relative
to the two original vertical intervals causing inter-
lace of subfields 1 and 3, and interlace of subfields 2
and 4. It is noted that this system will work without
any added sync pulses, but with some loss of vertical
resolution. r~e in no way limit ourselves to this
particular scheme and the essential nature of this
disclosure is in no way altered by using other methods
of interlace.
The sync pulse inserter circuit 65 as shown in
Fig. 3A operates as follows. The incoming video goes
to sync separator 100 and the horizontal and vertical
sync signals are detected and standardized by one-shots
97 and 98. The horizontal sync is multiplied by 4 in
phase lock loop 103 and counter 108 producing a 4H
signal. The 4H signal is divided by approximately 512
in counter 105. This counter is reset by the vertical
sync from the one-shot 97 outputing a square wave
exactly a field in duration and high for one subfield
and low for the other subfield. The first transition
of this square wave after the vertical sync triggers
one-shot 106 to output a pulse about 3H wide.
This pulse switches analoy gate 104 between the
incoming video buffered by buffer 101 and a DC voltage
2S from sa~ple and hold circuit 102 that is exactly equal
to the sync tip of video. This creates a vertical sync
pulse exactly in the center of the field to lock the
vertical oscillator in the monitor. The resultant
video is buffered by 107 to match 75 ohms.
This circuit 65 could be either in each monitor or
receiver or centrally located within a facility.
With the single camera method, the electronics of
which are schematized in Fig. 7, the left and right
images are formed by a ~ernier-type optical device 67
in front of the camera. The images are formed on the

3~
-2~-
pickup tube Eace plate in such a way, sho~/n in Figure
1, that one ima~e is scanned durinc3 the first half o~
the ca~era vertical fie]d and the second image during
the second half of the vertical field. The video next
passes through the vertical sub-field sync pulse
inserter ~5, giving it a 120 l~z vertical rate and then
to the 120 Hz monitor 66 and occluding glasses 12.
It is important to note that the camera vertical
sweep does not have to ccnform with the true vertical
axis. With some optical devices, it might be worth-
while to interchange vertical and horizontal axis on
both the camera and monitor as shown in ~ig. 6A and
Fig. 6C and described earlier.
We will now discuss a method for performing con-
vergence or correcting recentration with this stereo-
scopic system, as shown in Fig. 10.
At the
output of the camera for the single camera system
or the output of the alternate field switch on.the two
camera system, the composite video and sync signal is
split into two paths again. In one path there is a
fixed delay of 67 of about two video lines. In the
other path there is a variable delay 68 of zero to 4
lines. The two paths are then recombined by a video
switch 69. The video switch 69 is driven in such a way
that it will pass all sync pulses plus one camera's
video siqnal from the fixed delay path 67 and the other
camera's vi~eo signal only from the other delay path.
If the cameras were perfectly converged, the variable
delay 68 would be set to be equal to the fixed delay
67 so the left, right, and sync signals arrive in
coincidence with each other. To correct for con-
vergence or recentration errors,

3~
~5
the variable delay line 6~ is changed on the order of
S microseconds to correct for horizontal errors and on
the order of lines for vertical errors. The net effect
wo~ld be a horizontal or vertical picture shift of the
left image in relation to the right. This system would
not change any of the sync pulse relationships and thus
would allow the processed video to pass through the
television infrastructure. An alternate correction
scheme, would use only one variable delay line on one
video path and no delay on the other. In this scheme
the video switch would determine whether left or right
video was delayed. In any case, sync would not be
delayed.
A second method for convergence or recentration
control would be to delay or advance the horizontal
and/or vertical sync signals fed to one camera with
respect to the other. This system would be ine~-
pensive to implement, but would have the drawback
of producing a video signal with non-standard sync
signals. Even if such a signal were routed through
a time base corrector the results would be unpre-
dictable.
We will now discuss a safe and practical meansof ~owering PLZT occluding spectacles. Prior art has
advocated the use of PLZT occluding spectacles in the
field of television stereoscopy, but little reference
has been made to the safety and aesthetic problems
these devices present. State of the art PLZT elements
require from 200 to 700 volts in order to ooerate.
Our spectacle system as diagramed in Fig. 11 would
eliminate the safety problem with the use of lo~ poten-
tial wiring, a step-up transformer 71 and a diode-

-2G- '
resistor networlc 72. ~ switching power source 70,
which could be hattery powered anc3 carried on one's
person, outputs a low potential square wave in synchro-
nization with the television field rate. The square
5 wave travels on an insulated 3 conductor cable to the
spectacles 12. Mounted on the spectacles is a small
step-up transformer 71. This transformer 71 would
raise the voltage to the levels required to operate the
PLZT elements 12' and 12". The high voltage would pass
10 through a dioderesistor network 72. This would steer
one-half of the square wave's power to one element 12'
and the other half to the other element 12". The
entire transformer 71, resistor-diode 72, and PLZT 12'
and 12" elemen-t assembly could be sealed with a high
15 dielectric constant substance to provide user safety.
If the integrity of this potted assembly was violated,
the circuit within would be broken and power interrupted.
An alternative for powering the glasses employs
a fiber optic cable, transmitting a light source which
20 flashes in synchronization with the subfield rate, to
a photocell or phototransistor mounted in the spectacle
frames. The photocell or phototransistor then converts
light pulses into electrical pulses which are then
boosted in voltage to power the electro-optical switch-
25 ing elements.
Another technique we believe to be a useful con-
tribution to the art we have named skittering, and this
is diagrammatically illustrated in Fig. 13. Shown are
image forming tube 76, with face-plate 77, and aperture
30 mask 78. The geometric center of the area of the
faceplate 77 circumscribed by aperture mask 78 is
marked by cross hairs 79. Horizontally displaced, and
equidistance from 79, are new raster centers 79' and
79". [~sually the center of the raster corresponds

. 3~ fJ
--27--
exactly to 79. By electronic means we recenter the
raster to positions on the ~aceplate 77 given by 79'
and 79". It is important to state that no vertical
displacement of the center is to take place, but only
left and right horizontal translations to displace the
raster so that it will have new centers at 79' and 79".
Although the description given here is in terms
of analog techniques, using a CRT pickup tube, digital
pickup type devices may also be skittered, as will be
understood by those versed in the art, and we do not
wish to limit ourselves to analog applications.
Shown also are lenses 81 and 81' with their
optical centers 80 and 80', with lens axis 82 and
82', respectively. In usual practice with a single
lens, the a~is corresponds to a perpendicular dropped
from the single lens center intersecting the plane
of the faceplate 77 at its center 79.
Since the center of the image area has been
electronically relocated by shifting the raster so
that new centers of the image alternately correspond
to point 79' and 79", the new efEective axis located
on lines 82 and 82' are perpendicular to the plane
of faceplate 77, intersecting 791 and 79" respec-
tively. Skittering of the center of the raster to
79' and 79" respectively occurs at subfield rate,
and said shifting will be accompanied by a change
in the optical perspective of the image, first through
81, then through 81'. Such a shift will be on the
order of several millimeters.
Thus, two perspective points of view, one through
lens 81 and the other through 81', skittered at sub-
field rate, can be imaged with a single camera and
pickup tube or digital imaging device. Skittering
then provides a stereoscopic source, as shown here,
primarily for closeups or extreme macro photography

-2~-
o~ object~ up to several tens of millimeters across,
since the efEective interaxial separation, corre-
sponding to the distance between optical centers
~0 and 80' is re1atively low.
For simplicity we have o~itted the reflecting
separations, as shown in Fig. 6A and described else-
where in this disclosure.
Side-by-side optics, of the solex*type shown
here and in Fig. 6A, or frame splitters, which use
mirror arrangements similar to the Wheatstone
stereoscope, for imaging leEt and right fields
side-by-side on the same format, are far simpler
and less costly to design and build than the Bernier-
type over and under optics. Moreover, side-by-side
optics may be manufactured to have greater light
transmittance than over and under optics, and it is
easy to provide interchangeable prism assemblies for
various interaxial separations for side-by-side
optics while it is difficult to accomplish this
with over and under designs.
Therefore, there are advantages to using side-
by-side optics or frame dividers in conjunction with
skittering since this process electronically translates
the side-by-side format into the over and under format
in accordance with the system described herein.
Said skittered stereoscopic signal is entirely
compatible wlth the over and under 120Hz format we have
designed and built. The camera employed for skittering
must be adjusted to a 1?0 subfields per second rate,
with the subfield blanking area and/or sync pulses
added between the left and right subfields. Such video
output would produce a format, which when displayed on
an unmodified monitor would be identical to the format
shown in Fig. 1, and which would in all ways conform to
* Trade mark

LÇ~;3,~
-29-
the signal requirel-n~nts ~or stereoscopic transmission
set forth herein.
Those slcilled in the art ~ill appreciate that
while we have described our system in terms of SWitctl-
ing at field rate, switching at horizontal line rateis also possible. Although the preferred embodiment
described here is a 120 Hz system using field switch-
ing, a 60~1z system using alternate horizontal line
switching is useful in connection with dual optical
variations using single cameras and skittering.
For certain applications it may be desirable
to display our three-dimensional video signals on an
electronically unmodified monitor, receiving an above-
below signal. With reference to Fig. 12A, we show a
stereoscope hood attachment 70 to be added onto the
receiver or monitor, by placing said stereoscope hood
in intimate juxtaposition with the faceplate of CRT
70'. The format shown is in accordance with Fig. 1
with above image 3 right, and below image 4 left,
with blanking area 1 with added sync pulse signal.
The hood is essentially hollow and made of any light-
weight opaque material. The hood is a housing for
sheet polarizers 68 and 69 which are laid over right
and left above and below images respectively. The
polarizers have axes of polarization orthogonally
oriented as shown by the arrows.
The faceplate 75 of the hood contains optical
systems designed to act as a septum to segregate right
and left images, to refract light from above and below
images so that they may be viewed comfortably with the
eye muscles functioning as usual, to deanamorphose the
above and below vertically compressed images, and if
necessary, to provide convex lenses to aid in accommo-
dation of the images.

3~'~
-30-
With re~erence to Figs. 12~ and 12B, we will
examine components o~ the optical system at the
faceplate. Fig. l2s is a cross-section of the left
elements of the system, and is functionally identical
to the right elements, which are identified with the
prime superscript.
Sheet polarizers 71 and 71' have their axis of
polarization oriented orthogonally. The a~is of 71 is
oriented parallel with left below image 69 and the axis
of 71' is oriented parallel with right above image 68.
Prism 72 refracts or bends rays from image 69 so that
the axis of the left eye lens and the axis of the right
eye lens will lie in the same horizontal or median
plane, as is usual for normal vision. Prism 72'
performs a similar function for the right eye.
- The reader will note that elements of the optical
system are housed in mounts identified in Fig. 12~ as
part 76 for the left eye.
Cylindrical elements 73 and 73' deanamorphose
images 68 and 69 respectively and thereby restore
them to i~ages with normal shape and aspect ratio.
Elements 74 and 74' are needed only if the
distance ~ro~ the faceplate of the hood 70 to the
faceplate of CRT 70' is short enough to require said
25 elements ~or the purpose of aiding accommodation.
It should be called to the attention of the
reader that sheet polarizers 68 and 69, and 71 and
71' do not function in the same manner as polarizers
employed for image selection for projection of stereo-
scopic images. Rather they take the place of theseptum usually found in stereoscopes and provide an
optical rather than a physical means for segregation of
the left and right images.
The reader will also be aware that the order of
individ~al elements mounted in 76 may be varied, and

~2:~3~'~
-31-
that for purposes ol s~lperior correction additional
elements may be added which in no way would ma~e any
substantive change to the design disclosed herein.
And further, the reader will be aware that this
stereoscope design will work in conjunction with any
film or T~ over-and-under format, and could be used,
for example, for viewing motion pictures on an
editing machine viewing screen.
Several approaches are possible when transferring
stereoscopic film to tape for video transmission. The
approaches vary with the type of system used for the
original photography, or for the format of the master
to be used when dubbing to tape. We have transferred
double system stereoscopic film by transferring left
and right rolls to left and right tapes. The telecine
must guarantee synchronization of the film frame rate
with the TV field rate, so that the total number of
video fields produced for the right tape will be the
same as the total number of fields produced for the
left tape.
- In addition, there must be a correspondence
between the starting frames for left and right film
rolls and the odd or evenness of the video fields. In
the usual conversion of film to tape for NTSC video,
24 frames per second of picture must become 60 video
fields. Each successive frame is thus transferred to
t~o fields and thence three fields, thereby producing a
total of sixty fields per second from 24 frames of film
- picture.
Next the tapes containing the right and left
pictures are run in interlock and their video signals
passed through a digital effects box and manipulated to
conform to the above-below format described in this
disclosure. The video output of the digital effects
box is then recorded.

3~
-32-
~ hen transferrir1g to video from single s~stem
stereoscopic motion pictures, a sing1e pass ma~ be
employed to produce the necessary above and belo~
for~at. This is straightforward for the case o above
and below stereoscopic films, photographed in accord-
ance with designs by Bernier, U.S. Patent No. 3,531,191,
and in accordance with other practitioners oE the art.
The subfield blanking area and/or sync pulse must be
added between the above and below frames in order for
complete compatibility to be insured for the system
described herein.
We will conclude this disclosure by mentioning
that our system has many virtues, not the least of
which is its unique electronic-optical interface, which
presents many design advantages. Prior art stereo-
scopic systems, such as those put into practice by
Butterfield and others, employ stereopairs of images
disposed side-by-side and adjacent to each other on
the screen of a CRT. Such images may be optically
projected using dual projection optics similar to those
used for motion picture projection, or such images may
be viewed by means of a stereoscope hood placed in
close proximity with the display.
Such means are also possible to achieve with our
system since it can readily display the images on a CRT
or similar display device in a manner similar to that
described above. In addition, our technique allows
for display by means of active glasses using electro-
optical occluding elements, which heretofore has been
beyond the means of prior art techniques using adja-
cently disposed right and left images.
Thus, the optical-electronic interface built into
the system allows images from the same proyram source
to be viewed through a stereoscope-type device, or by
means of optical projection and viewing through passive

-33-
spectacles, or for disp]ay using alternate ~ields of
right-left information to be viewed by means of active
spectacles. Moreover, the s~stem encourages inter-
facing motion picture and electronic uses since motion
pictures may be readily converted to our video format,
especially those which have been photographed on
a modern over-and-under system.
Another feature of the above-below encoding of
stereoscopic video information, with regard to computer
graphics, is that programming of such images in video
memory is much simpler and easier to implement using
software with current computer video hardware than the
alternative of encoding successive fields with right-
left information. This is true because the above-
below format does not care about field memory, but onlycares about total image memory, and current hardware is
much more suited to above-below encoding than encoding
different images in even and odd fields because many
computers simply double each field to achieve NTSC
compatibility.
~ 'e have also devised means of transferring to
video double system motion pictures. High quality
motion pictures may also originate in our video
format and may be transferred from video to motion
picture film using well known art. Such video system
means for film display has many virtues, not the least
of which is the inherent flexibility of a double camera
ensemble which can automatically record both parts of
the stereopair onto a sin~le tape. ~otion picture
systerns seeking to exploit the virtues of doublç camera
rigs must result in photography which is made up of two
reels of film. Therefore, our system combines the best
aspects of double camera rigs and those of single
camera rigs. High speed optics are readily available,
it is easy to vary the interaxial separation, and zooms

3S~
may be achieved. ~ll of the aforementioned are tech-
nically impossible or very difficult to achieve witn
over-and-under optics which are used for the photo-
graphy of theatrical motion pictures.
Likewise it is obvious to those versed in the art
that by analogy with the preferred embodiment of this
invention, the left and right eye image pairs may be
presented without flicker by doubling the horizontal
sweep (double horizontal sync pulses) as well as
halving the horizontal resolution. A normal CRT would
then display the iwo images side by side but squeezed
anamorphically in the horizontal direction. A receiver
modified by analogous means to those described in the
present invention would display the unsqueezed images
sequentially mutatis mutandis. This system would also
be suitable for viewing with a stereoscopic hood for
video projector, and would interface in a straight-
forward way with such stereoscopic optics as those
described by Jacobsen U.S. Patent No. 3,433,561.

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Administrative Status

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Event History

Description Date
Inactive: IPC expired 2018-01-01
Grant by Issuance 1987-01-06
Inactive: Expired (old Act Patent) latest possible expiry date 1984-01-17

Abandonment History

There is no abandonment history.

Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
STEREOGRAPHICS CORPORATION
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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