U.S. patent application number 10/759385 was filed with the patent office on 2004-10-21 for flat panel display and a method of fabrication therefor.
Invention is credited to Faris, Sadeg M..
Application Number | 20040207801 10/759385 |
Document ID | / |
Family ID | 25132462 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040207801 |
Kind Code |
A1 |
Faris, Sadeg M. |
October 21, 2004 |
Flat panel display and a method of fabrication therefor
Abstract
Provided herein is a logic tree branch for steering
electromagnetic energy. The logic tree branch structure includes
active elements for directing said electromagnetic energy into one
of first and second paths. Further, corresponding passive elements
are disposed in the second path for directing electromagnetic
energy into a path parallel to the first path when the
electromagnetic energy is directed into said second path.
Inventors: |
Faris, Sadeg M.;
(Pleasantville, NY) |
Correspondence
Address: |
REVEO, INC.
85 EXECUTIVE BOULEVARD
ELMSFORD
NY
10523
US
|
Family ID: |
25132462 |
Appl. No.: |
10/759385 |
Filed: |
January 16, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10759385 |
Jan 16, 2004 |
|
|
|
08784440 |
Jan 16, 1997 |
|
|
|
6680758 |
|
|
|
|
Current U.S.
Class: |
349/196 ;
348/E13.014; 348/E13.037; 348/E13.038; 348/E13.039; 348/E13.04;
348/E13.044; 348/E13.059; 348/E9.024 |
Current CPC
Class: |
H04N 13/334 20180501;
G02B 27/145 20130101; H04N 13/361 20180501; H04N 13/337 20180501;
H04N 13/341 20180501; H04N 9/30 20130101; H04N 13/398 20180501;
H04N 13/239 20180501; H04N 13/339 20180501 |
Class at
Publication: |
349/196 |
International
Class: |
G02F 001/13 |
Claims
1. A logic tree branch for steering electromagnetic energy
comprising anactive element for directing said electromagnetic
energy into one of first and second paths and a passive element
disposed in said second path for directing said electromagnetic
energy into a path parallel to said first path when said
electromagnetic energy is directed into said second path.
2. A logic tree branch according to claim 1 further including a
source of said electromagnetic energy having a given wavelength and
circular polarization coupled to said active element.
3. A logic tree branch according to claim 2 wherein said active
element includes an element transmissive to said given polarization
and wavelength and reflective to said given wavelength and a
polarization opposite to said given polarization.
4. A logic tree branch according to claim 2 wherein said passive
element includes an element reflective to said given wavelength and
a polarization opposite to said given polarization.
5. A logic tree branch according to claim 2 wherein said active
element includes phase shifter means disposed between said source
of electromagnetic energy and said active element.
6. A logic tree branch according to claim 2 wherein said active
element includes an element made of cholesteric liquid crystal
material.
7. A logic tree branch according to claim 2 wherein said passive
element includes an element made of cholesteric liquid crystal
material.
8. A logic tree branch according to claim 2 further including a
programmable pulse of source connected to said active element.
9. A logic tree branch according to claim 2 further including means
connected to said source of electromagnetic energy for modulating
said source.
10. A logic tree branch according to claim 5 wherein said phase
shifter means includes a phase shifting material responsive to
different potential levels for switching said phase shifting
material between states which provide electromagnetic energy having
said given polarization and said opposite polarization.
11. A logic tree branch according to claim 5 wherein said phase
shifting means further includes electrode means for applying said
different potential levels to said phase shifter material.
12. A logic tree for steering electromagnetic energy comprising a
plurality of stages, the first of said stages including a branch
for directing said energy to a similar branch in each succeeding
stage, each of said stages containing 2.sup.n-1 branches where n is
the stage number.
13. A logic tree according to claim 12 wherein each of said
branches includes an active element for directing said
electromagnetic energy into one of first and second paths and a
passive element disposed in said second path for directing said
electromagnetic energy into a path parallel to said first path when
said energy is directed into said second path.
14. A logic tree according to claim 13 further including a source
of said electromagnetic energy having a given wavelength and
circular polarization coupled to said active element of said first
stage.
15. A logic tree according to claim 14 wherein said active element
includes an element transmissive to said given wavelength and
circular polarization and reflective to said given wavelength and
to a circular polarization opposite to said given circular
polarization.
16. A logic tree according to claim 14 wherein said passive element
includes an element reflective to said given wavelength and a
circular polarization opposite to said given circular
polarization.
17. A logic tree according to claim 14 wherein said active element
includes phase shifter means disposed in electromagnetically
coupled relationship with said active element.
18. A logic tree according to claim 14 wherein said active element
includes an element made of cholesteric liquid crystal
material.
19. A logic tree according to claim 14 wherein said passive element
includes an element made of cholesteric liquid crystal
material.
20. A logic tree according to claim 14 further including a
programmable pulsed source connected to said active element.
21. A logic tree according to claim 14 further including means
connected to said source of electromagnetic energy for modulating
said source.
22. A logic tree according to claim 14 further including half-wave
retarders disposed in electromagnetically coupled relationship with
selected of said active and passive elements of the last stage of
said plurality of stages to convert said electromagnetic energy
emanating from said active and passive elements to a single
circular polarization.
23. A logic tree according to claim 17 wherein said phase shifter
means includes a phase shifting material responsive to different
potential levels for switching said phase shifting material between
states which switch incident electromagnetic energy between said
given polarization and said opposite polarization.
24. A logic tree according to claim 23 wherein said phase shifting
means further includes means for applying said different potential
levels to said phase shifter material.
25. A flat panel logic tree display array for steering
electromagnetic radiation comprising a plurality of first logic
trees each of said first logic trees having a plurality of stages,
a single input port, a plurality of output ports, and wherein said
array has 2.sup.m.times.2.sup.n output ports and m and n are stage
numbers.
26. An array according to claim 25 further including a plurality of
sources of electromagnetic radiation each electromagnetically
coupled to said a single input port of an associated first logic
tree and having a given wavelength and circular polarization.
27. An array according to claim 25 further including a second logic
tree similar to each of said plurality of first logic trees having
a plurality of stages, a single input port and a plurality of
output ports each of said output ports of said second logic tree
being connected to a different one of said input ports of said
plurality of first logic trees.
28. An array according to claim 26 wherein the first stage of said
plurality of stages includes a branch for directing said radiation
to a similar branch in each succeeding stage, each of said stages
containing 2.sup.n-1 branches where n is the stage number.
29 An array according to claim 27 further including at least a
single source of electromagnetic radiation electromagnetically
coupled to said single port of said second logic tree.
30. An array according to claim 27 further including a half-wave
retarder electromagnetically coupled to selected ones of said
output ports of said plurality of first logic trees.
31. An array according to claim 27 further including a half-wave
retarder electromagnetically coupled to selected ones of said
output ports of said plurality of first logic trees.
32. An array according to claim 27 wherein said plurality of output
ports of said plurality of first logic trees are disposed in the
form of a rectilinear array.
33. An array according to claim 27 wherein said plurality of first
logic trees and said second logic tree are disposed in a orthogonal
relationship.
34. An array according to claim 27 wherein each of said plurality
of first logic trees is disposed in stacked relationship with
others of said first logic trees.
35. An array according to claim 27 wherein said plurality of output
ports of said second logic tree are remote from each said single
input port of said plurality of first logic trees.
36. An array according to claim 27 further including at least a
single source of electromagnetic radiation optically coupled to
said single input port of said second logic tree and means
connected to said at least a single source for modulating said at
least a single source of electromagnetic radiation.
37. An array according to claim 27 wherein the first stages of said
plurality of stages of said first logic trees and the first stage
of said second logic tree include a branch for directing said
radiation to a similar branch in each succeeding stage, each of
said stages containing 2.sup.n-1 branches where n is the stage
number.
38. An array according to claim 28 wherein each of said branches
includes an active element for directing said electromagnetic
radiation into-one of first and second paths and a passive element
disposed in said second path for directing said radiation into a
path parallel to said first path when said radiation is directed
into said second path.
39. An array according to claim 28 wherein said active element
includes an element transmissive to said given wavelength and
circular polarization and reflective to said given wavelength and
to a circular polarization opposite to said given circular
polarization.
40. An array according to claim 28 wherein said passive element
includes an element reflective to said given wavelength and a
circular polarization opposite to said given circular
polarization.
41. An array according to claim 28 wherein said active element
includes phase shifter means disposed in electromagnetically
coupled relationship with said active element.
42. An array according to claim 28 wherein said active element
includes an element made of cholesteric liquid crystal
material.
43. An array according to claim 28 wherein said passive element
includes an element made of cholesteric liquid crystal
material.
44. An array according to claim 28 further including a programmable
pulsed source connected to said active element.
45. An array according to claim 28 further including means
connected to said source of electromagnetic radiation for
modulating said source.
46. An array according to claim 28 further including half wave
retarders disposed in electromagnetically coupled relationship with
selected of said active and passive elements of the last stage of
said plurality of stages to convert said electromagnetic energy
emanating from said active and passive elements to a single
circular polarization.
47. An array according to claim 37 wherein each of said branches of
said first and second logic trees includes an active element for
directing said electromagnetic radiation into one of first and
second paths and a passive element disposed in said second path for
directing said radiation into a path parallel to said first path
when said radiation is directed into a first path.
48. An array according to claim 37 wherein said active element
includes an element transmissive to said wavelength and circular
polarization and reflective to said given wavelength and to a
circular polarization opposite to said given circular
polarization.
49. An array according to claim 37 wherein said passive element
includes an element reflective to said given wavelength and a
circular polarization opposite to said given circular
polarization.
50. An array according to claim 37 wherein said active element
includes phase shifter means disposed in electromagnetically
coupled relationship with said active element.
51. An array according to claim 37 wherein said active element
includes an element made of cholesteric liquid crystal
material.
52. An array according to claim 37 wherein said passive element
includes an element made of cholesteric liquid crystal
material.
53. An array according to claim 37 further including a programmable
pulsed source connected to said active element.
54. An array according to claim 37 further including means
connected to said source of electromagnetic energy for modulating
said source.
55. An array according to claim 37 further including half-wave
retarders disposed in electromagnetically coupled relationship with
selected of said active and passive elements to convert said
electromagnetic energy of the last stage of said plurality of
stages to convert said electromagnetic energy emanating from said
active and passive elements to a single circular polarization.
56. An array according to claim 41 wherein said phase shifter means
includes a phase shifting material responsive to different
potential levels for switching said phase shifting material between
states which switch incident electromagnetic radiation between said
given polarization and said opposite polarization.
57 An array according to claim 50 wherein said phase shifter means
includes a phase shifting material responsive to different
potential levels for switching said phase shifting material between
states which switch incident electromagnetic energy between said
given polarization and said opposite polarization.
58. An array according to claim 56 wherein said phase shifting
means further includes means for applying said different potential
levels to said phase shifter material.
59. An array according to claim 57 wherein said phase shifting
means further includes means for applying said different potential
levels to said phase shifter material.
60. A method for fabricating an array comprising the steps of:
forming a plurality of insulating media having a plurality of
wavelength and polarizing elements embedded therein at an angle
relative to the surfaces of said media such that the spacing
between elements halves for each different medium in said plurality
of said media, forming a phase shifter arrangement such that a
portions thereof of conductive material are disposed on one of said
surfaces of said media in registry with every other element in each
of said media and other portions of which of conductive material
are disposed on another of said surfaces overlapping all of said
elements, and, a phase shifting material disposed over at least
said every other element stacking said plurality of media such that
the topmost insulating medium has two elements and each succeeding
medium has twice as many elements as a preceding medium.
61. A method according to claim 60 wherein the steps of forming a
plurality of insulating media includes the steps of: stacking
alternating layers of an insulating material and a wavelength and
polarization sensitive material the thickness of said layers of
insulating material determining the spacing between said elements,
and slicing said layers at an angle to form said plurality of
insulating media with said elements embedded therein.
62. A method according to claim 60 wherein the steps of forming a
phase shifter arrangement include the steps of: depositing
transparent, conductive layers on said surfaces of said insulating
media, forming said portions of said conductive material on said
one of said surfaces of each of said media by photolithography,
affixing a spacer of insulating material about the periphery of
said one of said surfaces of each of said media, and introducing a
phase shifting material over said one of said surfaces of each of
said media.
63. A method according to claim 60 further including the step of
sealing the topmost of said media with a layer of insulating
material.
64. A method according to claim 60 wherein said insulating media
are made of SiO.sub.2.
65. A method according to claim 60 wherein said insulating media
are made of optically transparent layers.
66. A method according to claim 60 wherein said elements are made
of cholesteric liquid crystal material.
67. A method according to claim 60 wherein said angle is
45.degree..
68. A method according to claim 60 wherein said conductive material
is indium tin oxide.
69. A method according to claim 62 wherein said phase shifting
material is in liquid form.
70. A method according to claim 62 wherein said phase shifting
material is a liquid crystal.
71. A method according to claim 62 wherein said phase shifting
material is a solid state electro-optic material.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to display devices
for beam steering and scanning and, more particularly, to flat
panel display devices for beam steering and scanning which are
electronic in character and which further incorporate logic trees
which are designed to steer electromagnetic energy so that both
transmission losses and the number of energizing sources of an
imaging array are minimized. The devices include a multi-stage
imaging array made up of a plurality of stacked logic trees so
arranged that each stage of each logic tree includes active
steering elements which access twice as many like steering elements
and associated passive steering elements in each succeeding stage.
The active and passive elements incorporate cholesteric liquid
crystal (CLC) elements which are polarization sensitive disposed
within them at an angle of 45.degree.. The active elements include
variable half-wave retarders which, under control of a programmable
pulsed source change the polarization of incident energy on CLC
elements and provide a scanned line of electromagnetic energy to
the imaging cells disposed at the output of each logic tree. In
such an arrangement, array transmission losses are minimized and
one source of electromagnetic energy per logic tree is
required.
[0003] In another arrangement using a similar imaging array,
transmission losses are reduced over prior art input arrangements
and the number of sources of electromagnetic energy is reduced to
one. Using an input logic tree, fed from a single laser and
arranged perpendicularly to the array logic trees, the imaging
cells of the input logic tree act as inputs to the stacked logic
trees of the imaging array. In this way, a scanned line is
delivered from each imaging cell of the input logic tree to the
first active element of an associated array logic tree. From there,
under control of a programmable pulsed generator, portions of the
scanned line are directed to the output imaging cells of each of
the array logic trees. Two-dimensional images are built up in this
way by activating the imaging cells of each array logic tree in
succession. Three dimensional images may be obtained using an
approach similar to that just described by interleaving stereo
displaced images from a 3-D camera at the output imaging cells of
an imaging array by activating the first and every other logic tree
of an array with one image and the second and every other logic
tree with a stereo displaced image. Glasses which respond to a
different polarization for each eye are required to produce the 3-D
effect.
[0004] The present invention also relates to a method of
fabricating the above described imaging arrays by slicing stacked
alternating layers of insulating material and CLC material. To the
extent that a final imaging array requires that each logic tree
have twice as many CLC elements per stage as a preceding stage
after the first stage, the number of CLC element per stage may
doubled by halving the spacing between CLC elements during
fabrication. This is accomplished by halving the thickness of the
insulation disposed between layers of CLC material after setting
the initial spacing between CLC layers which are to be used as the
first stage of a logic tree. After producing layers of a given
thickness by slicing at a 45.degree. angle, transparent metallic
ground planes are formed. Then, using photolithographic and etching
techniques, electrodes are formed over every other CLC element. A
spacer element is then fixed to the periphery of each layer and the
resulting volume is filled with a phase shifter material. The
resulting stages are then stacked using as many as required to form
an imaging array with a desired number of imaging cells. Stacking
the stages, which are slices containing differently spaced CLC
elements automatically provides the logic trees which deliver
scanned line to the output imaging cells. The method uses
mass-production techniques and results in an inexpensive,
flat-panel display.
[0005] 2. Description of the Prior Art
[0006] Generally, there are two well-known techniques for the
steering and scanning of light beams. One is electromechanical and
the other is acousto-optical. Both techniques have severe
limitations. One such limitation is that arrangements incorporating
these techniques require a large volume, due to the small angel
through which the light beam, can be deflected. Thus, if it is
desired to scan a length B, the deflection arrangement has to be
positioned a distance, A, providing an A/B ration larger than
1.
[0007] All known systems require an A/B ratio larger than 1 and to
the extent that the arrangement of the present application can
provide A/B ratios which are very much less than 1, the resulting
structure may also be characterized as a flat-panel display. In the
known scanning approaches, scanning speed is relatively sluggish
due to the use of electromechanical or electro-acoustic elements.
Because such devices are eliminated in the scanning arrangement of
the present application, scanning speeds in the microsecond range
are achievable.
[0008] U.S. Pat. No. 4,670,744 filed Mar. 14, 1985 and issued Jun.
2, 1987 in the name of T. Buzak incorporates variable optical
retarders and liquid crystal chiral cells. This reference takes
advantage of the reflective and transmissive characteristics of
chiral cells as well as the ability of variable optical retarders
to convert one circular polarization to the other circular
polarization. However, when a beam containing image information is
projected along a given path in which the chiral cells and
retarders are disposed, the beam remains in that given path or is
retroreflected along the same path. Opposed to this, the
arrangements of the present application while they all incorporate
the reflection-transmission characteristics of chiral cells, they
all incorporate an ability to divert the reflected beams into other
paths. To the extent that the Buzak reference seek to provide a
three-dimensional display, all the images reflected must lie in a
plane parallel to the planes of the chiral cells. Otherwise
distortion and degradation of the reflected images would occur due
to the required lateral displacement of the chiral cells. In other
words, to provide the desired result, no diversion of the beam in
the Buzak reference can be tolerated.
[0009] U.S. Pat. No. 5,221,982, filed Jul. 5, 1991 and issued on
Jun. 22, 1993 to S. M. Faris is entitled Polarizing Wavelength
Separator. The patent relates to a polarizing wavelength separating
optical element in the form of a flat panel which causes each of a
plurality of polychromatic optical beams from a source, entering at
one surface and transmitted to another surface, to be converted,
with high conversion efficiency, into circularly polarized,
spectrally and spatially separated beams. The element is made of a
periodic array of cells; each of the latter incorporating a
plurality of subcells. One subcell 11 functions as a broadband
reflector, while each of the remaining subcells acts as a
polarizing, wavelength selective reflector. Each subcell comprises
a plurality of layers which are bonded together at their surfaces
and are oriented at a 45.degree. angle relative to the horizontal
surfaces of the panel. In each subcell, the plurality of layers
comprise two cholesteric liquid crystal, CLC films, which reflect
at a selected wavelength, at least one optical retarder and clear
substrates which provide mechanical support. The thicknesses of the
supporting substrates are designed to cause the beams transmitted
through the element to be spatially separated by appropriate
distances.
[0010] In the reference, all the elements utilized in the panel are
passive in character which constrain beams of electromagnetic
energy into paths which are fixed for all time. In
contradistinction to this, the present application, with it
electronically controllable retarders, provides paths for
electromagnetic energy which can be changed from instant-to-instant
taking advantage of both the transmissive and reflective
capabilities of CLC elements. The combination of a circularly
polarized input with controllable retarders and associated CLC
elements in the present invention provides the ability to scan a
beam from point to point in a panel-like display or to steer a beam
it can emanate from any location on an array of imaging cells.
Strictly passive arrays with their fixed paths cannot achieve these
results.
[0011] U.S. Pat. No. 5,459,591, filed Mar. 9, 1994 and issued Oct.
17, 1995 to S. M. Faris relates to beam steering and scanning
devices which utilize an imaging cell which incorporates a
solid-state cholesteric liquid crystal (CLC) element, an
electronically controlled, variable half-wave retarder and a source
of circularly polarized light. The CLC element is disposed to an
angle (45.degree.) relative to the path along which light from the
source is projected and is designed to reflect, at a given
wavelength, one circular polarization of light and transmit the
other. Using this characteristic, light of one polarization or the
other is presented to the variable retarder and depending on
whether or not it is actuated, light is either diverted into
another orthogonal path or remains in the original path. If another
similar imaging cell is disposed in the orthogonal path, light
incident on that cell can also be diverted into yet another path or
transmitted along the orthogonal path under control of a half-wave
retarders associated with said another imaging cells. By arranging
a plurality of imaging cells in the form of an array and accessing
each row of the cells of the array with a column of similar imaging
cells and by selectively activating half-wave retarders associated
with each of the cells, monochromatic or polychromatic light from a
single source or multiple sources may be steered to a selected cell
and reflected from its associated CLC element or elements.
Utilizing successive cells in the array and causing reflection of a
modulated beam or beams provides a frame in the manner of the usual
TV set which is viewed by the eyes as an integrated picture.
Successive frames, of course, provide the usual moving images.
SUMMARY OF THE INVENTION
[0012] The present invention relates to beam steering and scanning
devices which utilize cholesteric liquid crystal (CLC) elements
arranged in branches to form a logic tree. Each branch comprises an
active and passive CLC element; the former further comprising a
half-wave retarder and an electrode and the latter only the CLC
element. Each succeeding branch contains twice as many branches as
a preceding branch and, by activating active CLC element electrodes
under control of a programmable pulsed source, inputs applied to
the first stage of a logic tree are delivered as a scanned line of
electromagnetic energy or light to the imaging cells of the last
stage of the logic tree. By stacking identical logic trees with a
laser source for each tree, a flat panel imaging array or display
device is formed in which the transmission losses are
minimized.
[0013] Using a similar imaging array, transmission losses may be
further reduced by using a logic tree the outputs of which act as
inputs to the imaging array where formerly a plurality of lasers
were required. By positioning an input logic tree perpendicularly
to the similar logic trees of the imaging array, a single source of
energy provides an output at each of its imaging cells which acts
as an input to an associated logic tree of the imaging array. 2-D
and 3-D images are provided by applying modulation to lasers from
standard T.V. cameras and cameras designed to provide stereo
displaced images respectively. In the array which provides 3-D
images, an image and a stereo displaced image are interleaved to
provide the desired images each of which has a different circular
polarization.
[0014] The present invention also relates to a method of
fabricating structures which provide the above described features.
Since all the stages of a logic tree differ only in the number of
branches they contain, it was recognized that light beams, for
example, applied from a laser beam could pass through a number of
stages with minimum dispersion and maintain its original position
even though relatively large structures are used to control its
position. This recognition permitted the use of CLC elements,
electrodes and half-wave retarder material which need not be
divided into discrete elements in each logic tree. Thus, each CLC
element, each electrode and each retarder material may extend from
top-to-bottom or from side-to-side in each stage of an imaging
array.
[0015] Stages are fabricated by slicing layers of insulating
material and CLC material at an angle of 45.degree.. The thickness
of the insulating material controls the spacing between the
resulting CLC elements. Transparent layers, such as indium tin
oxide are formed on both sides of the layer or layers containing
spaced CLC elements. Using photolithographic techniques, one side
is masked and etched to form an electrode over every other CLC
element. A spacer element fixed to the periphery of each layer
where the electrodes have been etched forms a volume into which
half-wave retarder material is introduced in liquid form. In this
way, stages containing two, four, eight, sixteen, CLC elements and
so on have been massed produced. The stages are then stacked so
that each stage contains twice as many CLC elements as a preceding
stage forming logic trees the imaging cells of which form an
array.
[0016] The above described arrangements and their fabrication
technique provide flat panel displays which substantially reduce
transmission losses and the number of energizing sources. These
features combined with a novel and inexpensive manufacturing
technique are able to deliver a flat panel display which requires
neither a vacuum envelope nor unacceptable high voltages.
[0017] It is, therefore, an object of the present invention to
provide an imaging array which has reduced transmission losses
compared to prior art arrays.
[0018] Another object is to provide an imaging array which reduces
transmission losses while simultaneously reducing the
electromagnetic source requirement to one source.
[0019] Still another object is to provide an improved flat panel
display which is capable of providing both 2-D and 3-D images.
[0020] Still another object is to provide a method of fabricating
flat panel display which is inexpensive and conducive to
mass-production techniques.
[0021] The foregoing objects and features of the present invention
will become apparent from the following more detailed description
of preferred embodiments taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a schematic drawing of a logic tree of active and
passive Cholesteric Liquid Crystal (CLC) elements so arranged that
a single input to a first stage of the logic tree may be delivered
to any one of the outputs of the last stage of the logic tree.
[0023] FIG. 2 is a schematic diagram of a logic tree similar to
that shown in FIG. 1 which shows that the polarization of CLC
members may be varied to produce outputs having polarizations
different from those shown in FIG. 1.
[0024] FIG. 3 is an orthographic projection of eight logic trees
positioned one atop the other which, in accordance with the present
invention, provide 64 outputs using one source of electromagnetic
radiation per logic tree.
[0025] FIG. 4 is an orthographic projection similar to FIG. 3
except that, instead of a plurality of sources of electromagnetic
radiation, only a single source of radiation in combination with a
logic tree like that shown in FIG. 1 and disposed perpendicularly
to the stacked logic trees of FIG. 3 is required.
[0026] FIG. 5 is an orthographic projection of an imaging array and
its associated electronics which, in conjunction with viewing
glasses and stereo displaced images, provides a 3-D display.
[0027] FIG. 6 is an orthographic, cut-away projection of a
plurality of layers of insulating material like SiO.sub.2 and a
plurality of layers of CLC material interleaved with the layers of
insulating material. The interleaved layers are sliced at an angle
of 45.degree..
[0028] FIG. 7 is a cross-sectional view of a layer of insulating
material in which CLC members are disposed at an angle of
45.degree. and are spaced apart by a distance t.
[0029] FIG. 8 is a cross-sectional view of a layer of insulating
material in which CLC members are disposed at an angle of
45.degree. and is similar to FIG. 7 except that the CLC members are
spaced apart by a distance t/2.
[0030] FIG. 9 is a cross-sectional view similar to that shown in
FIG. 7 except that the CLC members are spaced apart by a distance
t/4.
[0031] FIG. 10 is a cross-sectional, orthographic projection of an
insulation layer with CLC members disposed at an angle of
45.degree. therein like that shown in FIG. 8 and further includes a
ground plane disposed on the bottom thereof.
[0032] FIG. 11 is a cross-sectional orthographic projection similar
to FIG. 10 except that it further includes electrodes disposed over
every other CLC member.
[0033] FIG. 12 is a cross-sectional view similar to that shown in
FIG. 11 further including a spacer disposed around the periphery of
the layer of insulation material with the resulting enclosed volume
filled with a phase-shifter material in liquid form.
[0034] FIG. 13 is a top view of a logic tree made up of layers like
those shown in FIGS. 7-12 after they have been stacked and aligned
to form an array like those shown in FIGS. 4, 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0035] Referring now to FIG. 1, there is shown a schematic drawing
of a logic tree of active and passive Cholesteric Liquid Crystal
(CLC) elements which are so arranged and controlled that a single
input to a first stage of the logic tree may be delivered to any
one of the outputs of the last stage of the logic tree by
appropriately switching electronically controlled half-wave
retarders associated with the active CLC elements of the logic
tree. By programming the switching of the half-wave retarders of
each stage of the logic tree, a laser input to the first stage of
the logic tree may, for example, provide a scanned version of the
input at the outputs of the last stage of the logic tree. The
application of the logic tree as a scanner will be described in
detail in what follows. It will also become clear that the same
embodiment has other applications.
[0036] Considering FIG. 1 in more detail, logic tree 1 is shown
consisting of a plurality of stages labeled STAGE 1-STAGE 4 wherein
each stage includes one or more branches each of which consists of
an active and passive CLC element. Thus, STAGE 1 consists of a
branch 2 which, in turn, includes active CLC element 18 and passive
CLC element 19. STAGE 2 consists of branches 3, 4; the former
including active CLC element 21 and passive CLC element 22 while
the latter includes active CLC element 23 and passive CLC element
24. STAGE 3 consists of four branches 5-8 each of the branches
consisting of active and passive CLC elements 31, 33, 35, 37 and
32, 34, 36, 38, respectively. Similarly, STAGE 4 consists of eight
branches 9-16 each of these branches including active and passive
CLC elements 41, 43, 45, 47, 49, 51, 53, 55 and 42, 44, 46, 48, 50,
52, 54, and 56, respectively, just like the previously mentioned
branches. At this point, it should be appreciated that many more
stages may be added to tree 1 with each succeeding stages having
twice as many branches as the preceding stage. Using this approach,
STAGE 4 in FIG. 1 has 2.sup.n-1 branches wherein n is the stage
number. Thus, STAGE 4 has 2.sup.4-1 or eight branches. Since each
branch has two CLC elements, each stage has 2.sup.n elements and,
for STAGE 4, sixteen elements. Thus, STAGE 10, for example, would
have 2.sup.10 or 1024 CLC elements providing one light output per
element or 1024 outputs.
[0037] Since FIG. 1 is representative of the way logic tree 1
operates regardless of the number of stages, only four stages have
been incorporated to clearly demonstrate how such a logic tree may
be used to provide a scanned light output from a plurality of
elements which are activated by an input from a single source of
electromagnetic energy.
[0038] Before describing the operation of FIG. 1, it should be
understood that the active CLC elements of each branch in FIG. 1 do
not depart from similar active elements shown in FIG. 1 of U.S.
Pat. No. 5,459,591 entitled "Electromagnetic Energy Beam Steering
Devices" in the name of S. M. Faris, which is hereby incorporated
by reference. The passive CLC elements of the present invention
differ from the active CLC elements in that the passive CLC
elements do not incorporate an electronically controlled, variable
half-wave retarder or .pi.-cell. Thus, each branch of logic tree 1
as represented by branch 2 of FIG. 1 includes an active CLC element
18 and a passive CLC element 19. The former includes a cholesteric
liquid crystal member 60, a transparent electrode 62, a ground
plane (not shown), and a controllable half-wave retarder 61 while
the latter includes a cholesteric liquid crystal member which is
identical to member 60. Since each of the branches 3, 4, 5-8 and
9-16 is identical with branch 2 of FIG. 1, each cholesteric liquid
crystal element and each half-wave retarder of each branch is
identified with the same reference numbers 60, 61 respectively.
[0039] In FIG. 1, active CLC element 18 and passive CLC element 19
of branch 2 both include cholesteric liquid crystal members 60
which are disposed at an angle, preferably 45.degree., within each
of the elements 18, 19. Members 60 are made from a nematic liquid
crystal material with chiral additives or polysiloxane side-chain
polymers which cause the cigar-shaped molecules to be spontaneously
aligned in an optically active structure of either a left-handed or
right-handed helix with a helical pitch, P. The twisting direction
and the pitch, P, of the helices are determined by the nature and
concentration of the additives. A CLC member, like member 60, has
all its helices aligned in one direction and is capable of
reflecting light, for example, having one circular polarization
having a characteristic wavelength or band of wavelengths.
Cholesteric Liquid Crystal (CLC) members 60 which are used in the
practice of the present invention and their method of fabrication
are shown in U.S. Pat. No. 5,221,982, filed Jul. 5, 1991 and issued
on Jun. 22, 1993 in the name of S. M. Faris. This patent is
herewith incorporated by reference. While CLC members 60 are shown
in FIG. 1 as being single elements, it should be understood that a
plurality of CLC members 60 may be substituted for each of the
members 60 to provide for the reflection and transmission of
circularly polarized radiation having a plurality of wavelengths or
band of wavelengths which are provided by a plurality of sources of
electromagnetic radiation. It should be appreciated that, in the
practice of the present invention, members 60 may be made of any
material which can be switched to reflect and/or transmit
electromagnetic energy by the application of electric or magnetic
fields to that material.
[0040] Half-wave retarders or .pi.-cells 61 shown schematically in
FIG. 1 are of the type shown and described in U.S. Pat. No.
4,670,744, filed March 14, 195- and issued on Jun. 2, 1987 in the
name of T. S. Buzak and may be utilized in the practice of the
present invention.
[0041] The Buzak patent is herewith incorporated by reference.
Alternatively, instead of CLC films, polarizing reflectors,
polarizing prisms or McNeill prisms may be utilized in the practice
of the present invention and are commercially available. When more
than a single wavelength of electromagnetic radiation is used in
the arrangement of FIG. 1, a broad band .pi.-cell may be utilized
to provide half-wave retardation of each wavelength to maintain the
same intensity level for each wavelength.
[0042] Logic tree 1 of FIG. 1 is activated from a source 17 of
electromagnetic radiation which may be a laser or any other source
of radiation the output of which may be converted from a linearly
polarized orientation to a circularly polarized orientation by
means of a quarter-wave plate (not shown) in a manner well known to
those skilled in the optical arts. If the resulting output is not
appropriately polarized, a half-wave retarder may be utilized to
provide the conversion from one circular polarization to the other
polarization.
[0043] For purposes of the present application, radiation emanating
from source 17 is circularly polarized in either a clockwise or
counter-clockwise direction. Lasers which are commercially
available may be utilized to provide outputs which fall within the
visible, infrared or ultraviolet spectra. While source 17 is shown
as a single source in FIG. 1, it should be appreciated that it also
represents a plurality of sources each having a different
wavelength. Thus, source 17 may include lasers which emit at the
red, green and blue wavelengths of the visible spectrum so that the
projected beam of radiation is a beam of light having a single
color or combinations of these wavelengths.
[0044] It should also be appreciated that source 17 may comprise
lasers or other sources of electromagnetic radiation which are
capable of being intensity modulated. In this way, the source
output may be varied in intensity from zero to a maximum intensity
including all gradations in between.
[0045] In FIG. 1, source of electromagnetic radiation 17 is shown
directly irradiating a member 60 of active element 18 of branch 2
from which it is either transmitted or reflected depending on the
polarization of the emitted radiation. The emitted radiation from
source 17 may have a single intensity or it may be an intensity
modulated signal provided by a television camera 25 or the like. By
appropriately programming .pi.-cells or half-wave retarders 61, an
unmodulated or intensity modulated signal is delivered in a scanned
manner to the active and passive CLC elements 41-56 of branches
9-16 of STAGE 4. In this way, an unmodulated or intensity modulated
beam of radiation is scanned across elements 41-56 providing an
output which is similar in every way to a single scan line of a
conventional television set.
[0046] If an input is provided in digital form, a digital-to-analog
converter 26 may be interposed between camera 25 and source 17 in a
well-known manner.
[0047] In FIG. 1, variable half-wave retarders 61 are activated by
a programmable pulsed source 27 which gets timing information from
camera 25 via interconnection 28. A plurality of driver
interconnections 29 extend from pulsed source 27 and each
interconnection 29 is connected to a separate electrode 62 which
applies an electric field to an associated half-wave retarder 61
when activated by pulsed source 27. In FIG. 1, fifteen driver
interconnections 29 would be utilized each one of which, when
pulsed, activates a separate variable half-wave retarder 61.
[0048] In operation, logic tree 1 is activated when source 17 is
activated. The object is to provide a scanned output from a single
input to a plurality of outputs in STAGE 4 of logic tree 1. It is,
therefore, required that the outputs of active and passive elements
41, 43, 45, 47, 49, 51, 53, 55 and 42, 44, 46, 48, 50, 52, 54 and
56, respectively, be activated so that outputs are obtained from
these elements in the order shown in FIG. 1. Since element 41 is to
provide the first output, if the input signal is right-hand
circularly polarized (RCP) radiation and all members 60 are
designed to be reflective of left-hand circularly polarized (LCP)
radiation, the RCP light passes through active elements 18, 21, 31
and 41 unhindered since these elements reflect LCP radiation and
transmit RCP radiation. An RCP radiation output, therefore, appears
at the output port of element 41.
[0049] In the next time period, half-wave retarder 61 of element 41
is activated by a pulse from pulsed source 27 via an
interconnection 29 to electrode 62 causing retarder 61 to introduce
a half-wave delay into the input RCP radiation which has passed
through active elements 18, 21 and 31 causing the RCP radiation to
be converted to LCP radiation. The LCP radiation then reflects from
member 60 of element 41 which is reflective of LCP radiation toward
member 60 of element 42 which is also reflective of LCP radiation.
The impinging LCP radiation is then reflected to the output port of
element 42.
[0050] In the next time period, an output is desired from the
output port of active element 43. To accomplish this, retarders 61
at the inputs of active elements 31 of STAGE 3 and active elements
43 of STAGE 4 are activated by applying pulses to their associated
transparent electrodes 62.
[0051] Once this is done, the RCP radiation at the input of active
element 31 is converted to LCP radiation and reflects from LCP
reflective member 60 over to LCP reflective member 60 of passive
element 32 where it is reflected toward active element 43. The LCP
input at active element 43 encounters a half-wave retarder 61 and
is converted to RCP radiation. The latter then passes unaffected to
the output port of active element 43 because its CLC member 60
reflects only LCP radiation.
[0052] In the next interval, pulsed source 27 deactivates half-wave
retarder 61 associated with active element 43 and continues
activation of the half-wave retarder 61 associated with active
element 31. In this way, the LCP radiation impinging on element 43
encounters no delay and remains as LCP radiation which is then
reflected from LCP reflective member 60 of element 43 toward
passive element 44. The thus reflected LCP radiation is reflected
from LCP reflective member 60 of element 44 to its output port.
[0053] Rather than tediously describing every passage through every
element, the order of the activation of half-wave retarders 61 will
be described since every path from input to output port can be
gleaned from the previous description and drawing shown in FIG. 1.
To obtain an output at active element 45, only the variable
half-wave retarders 61 associated with active elements 21 and 33
must be activated. To obtain an output at active element 46,
variable half-wave retarders 61 associated with active elements 21,
33 and 45 must be activated. To obtain an output at active element
47, the variable half-wave retarders associated with active
elements 21 and 47 must be activated. To obtain an output at
passive element 48, only the variable half-wave retarder associated
with active element 21 need be activated. An output at active
element 49 may be obtained by activating the half-wave retarders
associated with active elements 18 and 23. An output at passive
element 50 may be obtained by activating the half-wave retarders
associated with active elements 18, 23 and 49. To obtain an output
at active element 51, the half-wave retarders associated with
active elements 18, 35 and 51 must be activated. An output may be
obtained from passive element 52 by activating half-wave retarders
61 associated with active elements 18, 23 and 35. To obtain an
output at active element 53, half-wave retarders 61 associated with
active elements 18 and 37 must be activated. An output at passive
element 54 may be obtained by activating half-wave retarders 61
associated with active elements 18, 37 and 53. To obtain an output
at active element 55, half-wave retarders 61 associated with active
elements 18 and 55 are activated. Finally, active element 56 is
activated by activating half-wave retarder 61 associated with
active element 18.
[0054] Once half-wave retarders 61 are activated by applying pulses
to transparent electrodes 62 from programmable pulsed source 27 as
described hereinabove, a scanned output varying in intensity at
each of the active and passive elements 41 through 56 is obtained.
The outputs do not all have the same polarization and, for the
embodiment of FIG. 1, have a polarization pattern of alternating
RCP and LCP as the elements are scanned from left to right.
Recognizing that such variation is present is important where
outputs having the same circular polarization are desired or
required so that fixed half-wave retarders may be placed to convert
all the polarization's to the same polarization. Thus, in FIG. 1,
for example, fixed half-wave retarders 63 may be placed at the
outputs of active elements 41, 43, 45, 47, 49, 51, 53 and 55 to
convert their RCP outputs to LCP. The ability to do this conversion
is particularly important in arrangements which provide a 3-D
output because the perception of 3-D is based on having two
spatially displaced images each of which has a different
polarization.
[0055] If the input to active CLC element 18 in FIG. 1 is changed
to LCP and all the CLC members 60 in logic tree 1 are changed to be
reflective of RCP, the outputs obtained are exactly the same as
those shown in FIG. 1.
[0056] An identical output pattern to that shown in FIG. 1 is
obtainable where the input is LCP and all the members 60 are
reflective of LCP.
[0057] A pattern opposite to that shown in FIG. 1 is obtainable
where the input is RCP and all the members 60 are reflective of
RCP.
[0058] FIG. 2 is a schematic diagram of a logic tree 1 similar to
that shown in FIG. 1. It shows only the logic tree without the
associated laser and electronics. The purpose is to show that the
polarization of members 60 reflective of different polarizations
may be varied to produce outputs having different polarizations
from those shown in FIG. 1. Each of the boxes representing active
and passive elements in FIG. 2 contains either the letter L or R
indicating that the CLC member 60 therein is reflective of either
left-handed or right-handed circular polarization. Without going
into exhaustive detail, suffice it to say that the outputs shown in
FIG. 2 are obtained from an LCP input having the following
polarization pattern when retarders 61 are switched in the same
order as described in connection with FIG. 1:
[0059] LRRL RLLR RLLR LRRL
[0060] A pattern different from that shown above would be obtained
if the input polarization were changed to RCP and members 60 of
logic tree 1 were reflective of polarization's opposite to those
shown in FIG. 2. The output pattern is as follows:
[0061] RLLR LRRL LRRL RLLR
[0062] The foregoing illustrates how the output polarization may be
controlled for applications where information is polarization
encoded or scrambled; transmitted and decoded or unscrambled by
using a key which controls the variable half-wave retarders 61.
[0063] From the point of view of ease of manufacturing, logic trees
having the same CLC members 60 are the most advantageous as will be
seen when the fabrication process is described hereinbelow.
[0064] The arrangement of FIG. 1 provides an advantage over the
scanning arrangement shown in U.S. Pat. No. 5,459,591 in that input
light has to traverse, in a 1024.times.1024 array, 1024 CLC members
2 (in the patent) to provide an output at its furthest imaging cell
1 (in the patent). If each CLC member has transmissibility (T), the
final imaging cell will have a transmissibility of (T).sup.1024.
Thus, even with a transmissibility approaching 1, say 0.999, the
output at the 1024.sup.TH imaging cell would be: (0.999).sup.1024
which, to all intents and purposes, is zero.
[0065] Opposed to this is the present approach where, to provide
the last output in a 1024.times.1024 array, only twenty CLC members
60 or two per stage need to be traversed providing a
transmissibility of (T).sup.20. Under these conditions the 1024th
output, assuming T=0.999, would be (0.999).sup.20 which is
approximately ninety percent of the input intensity. The minimum
transmissibility for a ten stage array would be (T).sup.10 or one
transition per stage.
[0066] From the foregoing, while logic tree 1 of FIG. 1 represents
an improvement over the prior art in terms of output light
intensity, it should be clear that each logic tree 1 requires its
own input laser or source of electromagnetic radiation 17. Thus, to
provide an 8.times.8 array, for example, eight logic trees 1 would
have to be stacked in the manner shown in FIG. 3.
[0067] FIG. 3 is an orthographic projection of eight logic trees 1
positioned one atop the other which, in accordance with the
teaching of the present application, provide 64 outputs. One source
of electromagnetic radiation 17 per logic tree 1 is required.
[0068] Because of space limitations, the showing of FIG. 3 has been
limited to the use of only three of the STAGES of FIG. 1. Also,
since each of logic trees 1 in FIG. 3 is identical with the other
logic trees 1, only the topmost logic tree 1 with its CLC members
60 and variable half-wave retarders 61 have been shown. Also, as
will become clear hereinafter, the dimensions shown are not to
scale.
[0069] In FIG. 3, 8.times.8 array 70 is shown which comprises eight
logic trees 1 stacked one atop the other. Each logic tree 1 is
comprised of three stages, STAGE 1, STAGE 2, and STAGE 3. STAGE 1
comprises branch 2; STAGE 2 comprises branches 3,4 and STAGE 3
comprises branches 5-8 as shown in FIG. 1. Each branch includes
active and passive CLC elements similar to those shown in STAGES
1-3 of FIG. 1 and each of the active and passive elements includes
a cholesteric liquid crystal member 60 which is positioned at an
angle of 45.degree. within each of the active and passive elements
of array 70. Also, included are variable half-wave retarders 61
which are arranged in FIG. 3 just like the 1 variable retarders 61
in STAGES 1-3 of FIG. 1. In FIG. 3, each logic tree 1 is activated
by an associated source of electromagnetic radiation 17, preferably
a laser, thus requiring a total of eight sources 17. As each laser
is actuated, variable half-wave retarders 61 are actuated as
described in connection with FIG. 1 hereinabove and the output of
each laser 17 appears as a scanned modulated signal going from left
to right at the outputs of imaging cells 71 of each of logic trees
1. In the arrangement shown in FIG. 3, sources 17 and retarders 61
may be actuated sequentially or simultaneously. If the outputs of
sources 17 are converted to right-hand circular polarization (RCP)
and all CLC members 60 are reflective of left-hand circular
polarization (LCP), the outputs of each logic tree 1 of FIG. 3 will
be the same as those shown in FIG. 1, namely:
[0070] RLRL RLRL
[0071] As suggested in connection with the description of FIG. 1,
fixed half-wave retarders may be appropriately positioned to make
all the outputs have the same polarization.
[0072] While the number of lossy transitions per logic tree has
been reduced over that shown in the prior art, this has been
accomplished by the use of a source 17 for each logic tree 1
incorporated in an array 70. With arrangements like that shown in
FIG. 3 expanded to a 1024.times.1024 array, for example, 1024
sources 17 would be required. This requirement can be eliminated
and the number of sources reduced to one by using a logic tree 1
like that shown in FIG. 1, the outputs of which, provided from a
single source 17, act as inputs to an array 70 like that shown in
FIG. 3.
[0073] This will become clear from a consideration of FIG. 4 which
is an orthographic projection similar to FIG. 3 except that,
instead of a plurality of sources 17, only a single source 17, in
combination with a logic tree 1 like that shown in FIG. 1, disposed
perpendicularly to the logic trees 1 of FIG. 3 is required.
[0074] Considering FIG. 4 in more detail, array 70 is identical
with array 70 shown in FIG. 3. Also, source of electromagnetic
radiation 17 in FIG. 4 is similar to sources 17 shown in FIB. 3. In
FIG. 4, an input logic tree 72 is shown disposed between array 70
and source 17 such that each imaging cell 71 of logic tree 72 acts
as an input to an associated logic tree 1 of array 70. Thus, the
uppermost imaging cell 71 of input logic tree 72 provides an input
to the leftmost element of the topmost of logic trees 1 of array
70. This input which may be an intensity modulated signal from
source 17, is scanned across the imaging cells 71 of the topmost
logic tree 1 of array 70 in a manner analogous to the scan of a
television frame. When the scanned output of the topmost logic tree
1 reaches its last imaging cell 71, the output of source 17 is
switched to the next imaging cell 71 (immediately beneath the
topmost imaging cell 71) of logic tree 72. The output of that next
imaging cell then acts as the input to the logic tree 1 immediately
beneath the topmost logic tree 1 of array 70. The inputs to the
last mentioned logic tree 1 are then delivered to the imaging cells
71 of that logic tree 1 in sequence from left-to-right providing a
scanned, intensity modulated signal similar to that of a television
scan line.
[0075] Each of the remaining imaging cells 71 of input logic tree
72 is then actuated by programming electrodes 62 and variable
half-wave retarders 61 associated with logic tree 72 in the same
manner described hereinabove in connection with FIG. 1. Similarly,
each of the logic trees 1 of array 70 is actuated by outputs from
an associated imaging cell 71 of input logic tree 72. Then, under
control of programmed electrodes 62 and half-wave retarders 61,
these outputs, now inputs, to an associated logic tree 1, are
delivered to the imaging cells 71 of each logic tree 1 as a scanned
line having portions which may vary in intensity from imaging cell
71-to-imaging cell 71. In this way, by accessing logic trees 1 from
top-to-bottom, for example, in FIG. 4, an image is built up which,
depending on the imaging cell density, can provide images of
extremely high resolution.
[0076] From the foregoing, it should be clear that the modulated
output of a single source 17, preferably a laser, may be delivered
to the imaging cells 71 of a plurality of stacked logic trees 1
like array 70 in FIG. 4. As shown in FIG. 4, the use of an input
logic tree 72 permits the use of a single source 17 as opposed to
the multiplicity of sources 17 shown in FIG. 3. The value of the
arrangement shown in FIG. 4 becomes more apparent when it is
recalled that for a 1024.times.1024 array embodiment like FIG. 3,
1024 lasers would be required. Thus, in addition to reducing the
number of lossy transitions as provided by the embodiment of FIG.
3, the embodiment shown in FIG. 4 also reduces the number of
sources 17 required to the absolute minimum of one. While the
electronic equipment required to operate displays like those shown
in FIGS. 3, 4, has not been shown, it should be appreciated that
the same components as shown in FIG. 1 and which are well-known in
the imaging arts may be utilized in the practice of the present
invention. Thus, timing information obtained from camera 25, for
example, is applied via interconnection 28 to programmable pulsed
sources 27. The latter then applies switching signals to both logic
tree 72 and each of logic trees 1 to appropriately control their
electrodes 62 and half-wave retarders 60 so that a scanned energy
output may be delivered from the imaging cells 71 of each logic
tree 1 and input logic tree 72.
[0077] Referring now to FIG. 5, an orthographic projection of an
imaging array is shown which, in combination with viewing glasses
and stereo displaced images provides a 3-D display.
[0078] In FIG. 5, input logic tree 72 is accessed by a source 17 of
electromagnetic radiation which is modulated by outputs of a
stereoscopic television camera 73 via interconnection 74. The two
outputs from stereo camera 73 are stereo displaced so that, if they
are separated one from the other by some characteristic like
polarization, the two resulting images may be delivered one to each
eye (using appropriate glasses) and combined in the brain to
provide a three-dimensional image.
[0079] One of the images is provided by applying scanned lines from
stereo camera 73 via interconnection 74 to laser 17. The output of
the latter is then applied to input logic tree 72 from which
scanned line outputs are delivered from the topmost and alternate
imaging cells 71 under control of programmable pulsed source 75
which actuates variable half-wave retarders 61 thereof via
interconnections 76. The output from the topmost of imaging cells
71 of input logic tree 72 is applied for a given interval to
leftmost member 60 of the uppermost of logic trees 1. At the same
time, variable half-wave retarders 61 under control of programmable
pulsed source 27 are appropriately actuated so that a portion of
the scanned line from stereo camera 73 is delivered to each of the
imaging cells 71 of the uppermost of logic trees 1 of array 70.
[0080] In the instance of FIG. 5, each imaging cell 71 of array 70
is illuminated for a time equal to 1/8 the given interval of a
scanned line from camera 73. For a 1024.times.1024 array, the
illuminating time would be 1/1024.sup.TH of the scanned line
interval.
[0081] The first image is completed by applying scanned lines from
stereo camera 73 via interconnection 74 which modulate laser 17
during each alternate interval after the first to each alternate
imaging cell 71 after the first imaging cell 71 of input logic tree
72. Each scanned line is delivered to the imaging cells 71 of each
alternate logic tree 1 of array 70 in the same manner described in
connection with the delivery of the first scanned line to the
uppermost of logic trees 1 of array 70.
[0082] The stereo displaced image from stereo camera 73 is
delivered as scanned lines via interconnection 74 to laser 17 where
they modulate the output of laser 17. The stereo displaced scanned
line outputs are delivered to laser 17 during the second and
alternate intervals after the second interval. The first stereo
displaced output from laser 17, under control of programmable
pulsed source 75 which appropriately actuates the variable
half-wave retarders 61 of input logic tree 72, is delivered to the
second-from-the-top of imaging cells 71 of logic tree 72 as a
scanned line. This last mentioned output acting as an input to the
leftmost CLC member 60 of the second-from-the-top of logic trees 1
of array 70 is delivered to the imaging cells 71 of the
second-from-the-top of logic trees 1 of array 70 under control of
programmable pulsed source 27 as portions of the scanned line
output of laser 17.
[0083] As with the first image generation, the imaging cells 71 of
the stereo displaced image are illuminated for a time equal to 1/8
the given interval of a scanned line.
[0084] The stereo displaced image is completed by applying scanned
lines from stereo camera 73 via interconnection 74 to laser 17
during each alternate interval after the second interval to each
alternate imaging cell 71 after the second imaging cell 71 of input
logic tree 72. Each stereo displaced scanned line is delivered to
the imaging cells 71 of the second and alternate logic trees 1 of
array 70 in the same manner described in connection with the
delivery of the first stereo displaced scanned line to the
second-from-the-top of logic trees 1 of array 70.
[0085] If the polarization applied to logic trees 1 is RCP and the
members 60 thereof are designed to reflect LCP, logic trees 1
provide an image at their imaging cells 71 in the same way
described in connection with FIG. 1 and the resulting outputs will
have polarizations like those shown in FIG. 1. The polarizations at
STAGE 3 for each of logic trees 1 are:
[0086] RLRL RLRL
[0087] To obtain this result, however, input logic tree 72 must
provide RCP at all its imaging cells 71. This requires an RCP input
from laser 71, a logic tree with elements which reflect LCP and
fixed half-wave retarders 63 (not shown) disposed after imaging
cells 71 which provide LCP outputs.
[0088] To obtain a single polarization for all of the outputs of
first and alternate logic trees 1 of array 70, for example, RCP,
the LCP outputs of these logic trees 1 must be converted to RCP.
This is accomplished by interposing fixed half-wave retarders 63
over the imaging cells 71 having LCP outputs.
[0089] Similarly, to obtain a single but opposite polarization for
all of the outputs of the second and alternate logic trees 71, for
example, LCP, the RCP outputs of these logic trees 1 must be
converted to LCP. This is accomplished by interposing fixed-half
wave retarders 63 over the imaging cells 71 having RCP outputs.
[0090] At this point, two stereo-displaced images appear at the
output imaging cells 71 of array 70. One image has an RCP
polarization while the other has an LCP polarization. Then, using
glasses which have one lens which passes RCP and another lens which
passes LCP, a 3-D image is perceived by a viewer.
[0091] In connection with the 3-D embodiment of FIG. 5, it should
be appreciated that outputs from stereo camera 73 may be in either
digital or analog form. If the former, the digital signals may be
converted to analog signals using a digital-to-analog converter in
a well-known way. Also, to the extent that logic trees 1 are
provided with signals representing a scanned line of an image and a
stereo displaced image, these signals are arranged to alternately
access alternate ones of logic trees 1 in succession until two
stereo displaced images are formed at the imaging cells 71 of array
70. The scanned lines of an image and a stereo displaced image are
electronically interlaced so that source 17 is modulated first by
signals representing a scanned image and then by signals
representing a scanned stereo displaced image and so on in
succession until the two images are formed.
[0092] From FIG. 5, it can be seen that, for a 3-D array, two
4.times.8 interleaved arrays are required, one for an image and
another for a stereo displaced image. Extrapolating this
information to a practical level, if 1024 imaging cells are wanted
for each image, an array of 2048.times.10.sup.24 imaging cells
would be required. Using the same approach as demonstrated by FIG.
5, two 512.times.1024 interleaved arrays may be used with the
sacrifice of some resolution. In FIG. 5, logic trees 1 have been
interleaved horizontally for ease of fabrication but, they may be
interleaved vertically without departing from the spirit of the
present application.
[0093] Referring now to FIG. 6, there is shown an orthographic,
cut-away projection of a plurality of layers 80 of insulating
material, like SiO.sub.2, polycarbonate, acrylic or any other
appropriate optically transparent material, and a plurality of
layers 81 of cholesteric liquid crystal (CLC) material interleaved
with layers 80.
[0094] In FIG. 6, layers 80, 81 are subjected to a slicing
operation which cuts into layers 80, 81 at an angle, preferably
45.degree.. Layers 80, 81 may be cut by saws, lasers, jets or other
appropriate tool to provide layers 82 which contain CLC members 60
disposed at an angle of 45.degree. in insulating material as shown
in FIG. 7.
[0095] FIG. 7 is a cross-sectional view of a layer of insulating
material in which CLC members 60 are disposed at an angle of
45.degree.. The spacing of CLC members 60 is determined by
controlling the thicknesses of insulating layers 80 prior to the
slicing step of FIG. 6. Since alignment of CLC members 60 is
important in transmitting electromagnetic energy from
stage-to-stage the spacing of members 60 must be carefully
controlled. Thus, in FIG. 7, the spacing between CLC members 60 is
t units and could comprise STAGE 1, for example, of array 70 of
FIG. 4.
[0096] FIG. 8 is a cross-sectional view of a layer of insulating
material in which members 60 are disposed at an angle of 45.degree.
and is similar to FIG. 7 except that members 60 are spaced apart by
t/2 units. Layer 82 and other like layers are fabricated by slicing
an arrangement like that shown in FIG. 6 except that the
thicknesses of layers 80 of insulating material are reduced to half
that shown in FIG. 6. After slicing a stack like that shown in FIG.
6, the resulting layer 82 with a spacing of t/2 between members 60
could comprise stage 2, for example, of array 70 of FIG. 4.
[0097] FIG. 9 is a cross-sectional view of a layer of insulating
material in which members 60 are disposed at an angle of 45.degree.
and is similar to FIG. 7 except that members 60 are spaced apart by
t/4 units. Layer 82 in FIG. 9 is fabricated by slicing an
arrangement like that shown in FIG. 6 except that the thicknesses
layers 80 would be reduced to one-quarter that shown in FIG. 6.
After slicing a stack like that shown in FIG. 6, the resulting
layer 82 with a spacing of t/4 between members 60 could comprise
STAGE 3, for example, of array 70 of FIG. 4.
[0098] The spacing of members 60 is always reduced by half as
additional stages are added so that higher and higher resolutions
may be obtained. Thus, for an array with ten stages, the spacing
between CLC members 60 would be t/512 units.
[0099] By slicing arrangements like that shown in FIG. 6 and
controlling the thicknesses of layers 80, layers 82 with members 60
spaced apart by different amounts like those shown in FIGS. 7-9 may
be easily obtained. As will be seen below, layers 82 with
appropriately spaced members 60 may be stacked to produce an array
70 like that shown in FIG. 4 or an array having as many stages as
desired. This can be done on a mass-production basis to produce
literally thousands of layers like layers 82 of FIGS. 7-9.
[0100] FIG. 10 is a cross-sectional, orthographic projection of a
layer 82 which contains CLC members 60 disposed at an angle of
45.degree. therein. Layer 82 in FIG. 10 is similar to layer 82 of
FIG. 8 except that in FIG. 10, a ground plane 83 is deposited or
formed on the bottom of layer 82. Layer 83 is transparent and
metallic in character and acts as a ground plane for subsequently
deposited electrodes which activate variable half-wave retarders
61. A material like indium-tin oxide (ITO) may be deposited or
formed in a well-known way on the bottom of layer 82 of FIG. 10.
The transparency of ITO, of course, permits the transmission of
light energy from stage-to-stage with little or no loss in
intensity.
[0101] Referring to FIG. 11, there is shown a cross-sectional,
orthographic projection similar to FIG. 10 except that electrodes
84 are shown disposed over every other CLC member 60, like they
would be if layer 83 of FIG. 11 were to be utilized as a STAGE 2 in
an array 70 like that shown in FIG. 4. This pattern of electrode
spacing will always be the same regardless of which stage is being
considered. A reconsideration of FIG. 1 shows this to be true since
each stage always comprises at least one branch consisting of
active and passive CLC elements. Electrode 84 (62 in FIG. 1) is
always associated with and forms a part of variable half-wave
retarders 61 which, in turn, is always associated with the active
CLC element of any branch. Like ground plane 83, electrode 84 is
comprised of indium-tin-oxide (ITO) material which is transparent
to the electromagnetic radiation being utilized. To obtain
electrodes 84 in the form shown in FIG. 11, indium-tin oxide is
formed atop layer 82 and, using well-known lithographic, masking
and etching techniques, electrodes 84 are appropriately positioned
over every other CLC member 60. Rather than carrying out two
separate deposition steps for ground plane 83 and electrodes 84,
the ITO material may be formed simultaneously on each side of layer
82. Then, the photolithographic, masking and etching steps are
carried out.
[0102] Referring now to FIG. 12, there is shown a cross-sectional
view of a layer 82 similar to that shown in FIG. 11 except that a
spacer is added around the periphery of layer 82 and the thus
enclosed volume is filled with a phase-shifter material in liquid
form.
[0103] In FIG. 12, a spacer 85 is formed around the periphery of
layer 82 by, for example, gluing a spacer 85 of insulating material
around the edge of layer 82. Spacer 85 separates layers 82 from
other overlying layers and defines the volume into which
phase-shifter material 86 is placed.
[0104] FIG. 13 is a top view of a logic tree 1 made up of layers 82
like those shown in FIGS. 7-12. The arrangement of FIG. 13 shows
the topmost logic tree 1 of FIG. 4 after it has been fabricated in
accordance with the teaching of the present application. FIG. 13
can also be considered a side-view of input logic tree 72 since its
structure does not depart in any way from the structure of logic
tree 1.
[0105] One way of assembling the structure of FIG. 13, is to stack
a finished layer 82 like that shown in FIG. 12 on a finished layer
82 like that shown at the bottom of FIG. 13. Another layer 82 like
that shown at the top of FIG. 13 is stacked atop the finished layer
82 of FIG. 12. The layers are glued together with the topmost layer
82 forming STAGE 1 as shown in FIG. 4; the middle layer 82 forming
STAGE 2 as shown in FIG. 4 and the bottom layer 82 forming STAGE 3
as shown in FIG. 4. Thus, inputs provided to the leftmost CLC
member 60 of topmost layer 82 will, under control of inputs to
electrodes 84 from pulsed source 27, appear as outputs emanating,
from left-to-right, from CLC members 60 of bottommost layer 82 as a
scanned line of modulated or unmodulated light.
[0106] For the array, once stacked, the top and bottom thereof may
be covered with insulating layers, one of which contains holes
which register with the ends of electrodes 84 and ground planes 83.
Thus, even when logic trees 1 are not being utilized, their
associated electrodes 61, 84 which extend from top-to-bottom of
array 70 and are electrically connected as shown in FIG. 5 are
simultaneously energized.
[0107] Inputs to the stacked logic trees 1 are provided, as shown
in FIG. 4, from imaging cells 71 of input logic tree 72. The
orientation of input logic tree 72 with respect to array 70 is best
shown in FIG. 4 which does not depart in any way from the
arrangement of FIG. 13. The latter figure merely shows the
structural details to better effect Thus, as previously explained
in FIG. 4, outputs from imaging cells 71 of input logic tree 72 are
scanned from top-to-bottom of tree 72 and each output initially
accesses the leftmost member 60 of its associated logic tree 1 such
that outputs appear at imaging cells 71 of array 70 as a plurality
of left-to-right scans which go from the topmost logic tree 1 to
the bottommost logic tree 1 of array 70.
[0108] Input logic tree 72 may take the form of an array 70 rotated
90.degree. so that imaging cells 71 there of register with the
leftmost retarder 61 of each of the logic trees 1 like lasers 17 as
shown in FIG. 3. In this instance, only a single logic tree 1 of
the rotated array 70 is energized.
[0109] Alternatively, the array shown in FIG. 13 may be fabricated
without introducing the phase shifter material 86. The structure of
FIG. 13 is then sliced in a direction parallel to the surface there
of resulting in a structure similar to input logic tree 72 as shown
in FIG. 4. The resulting slice is placed on an insulating layer and
bonded to it. A cover layer of insulating material having holes
therein which register with electrodes 84 and ground planes 83 is
fabricated by drilling or etching using well-known
photolithographic techniques. The volumes enclosed by the
insulation layer are now filled with liquid phase shifter material
86. The cover layer is affixed to the other side of the logic tree
slice. A metallic layer such as aluminum is then deposited on the
surface of the cover layer and in the holes previously formed
therein. Then, using well-known photolithographic masking and
etching techniques, conductors to electrodes 84 in a ground planes
83 are formed
[0110] Without going into exhaustive detail, it should be
appreciated that the side of input logic tree 72 of FIG. 4 may be
butted against the back of array 70. In this way, the overall
thickness of the arrangement of FIG. 4 is substantially reduced.
Well-known optical techniques using reflectors may be used to apply
a 90.degree. turn to light emanating from imaging cells 71 of tree
72 when it is butted against the back of array 70.
[0111] Since electrodes 84 extend from front-to-back on each logic
tree 1 as shown, for example, in FIG. 13, they are best accessed
from the front or back of the array with activating metallic lines
29, as shown in FIG. 4, extending in insulated spaced relationship
with a surface of array 70 to a plug which can be connected to
pulsed source 27, for example. This may be accomplished using
well-known photolithographic and etching techniques.
[0112] The arrangements shown in FIGS. 6-12 may have the following
typical dimensions:
1 Layers 82 0.5 mm thick and up Electrodes 84 500.ANG. to 1000.ANG.
thick Ground Planes 83 500.ANG. to 1000.ANG. thick Spacer 85 1.mu.
to 10.mu. thick Elements 60 2.mu. to 30.mu. thick Cells 71 0.5 mm
wide and up. May exceed 10 cm
[0113] Typical voltages applied to electrodes 84 may range between
5V and 100V.
[0114] From the foregoing, it should be clear that arrays 70 may
range in size from that typical of T.V. sets used in the home to
displays similar to those used in stadia. The resulting arrays are
flat, light weight, require but a single laser source or multiple
laser sources and are inexpensive and easily fabricated.
* * * * *