U.S. patent number 3,848,247 [Application Number 05/330,227] was granted by the patent office on 1974-11-12 for multi-dimensional liquid crystal assembly addressing system.
This patent grant is currently assigned to North Hills Electronics, Inc.. Invention is credited to Solomon Sherr.
United States Patent |
3,848,247 |
Sherr |
November 12, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
MULTI-DIMENSIONAL LIQUID CRYSTAL ASSEMBLY ADDRESSING SYSTEM
Abstract
A multi-dimensional matrix addressing system comprising an
assembly of liquid crystal units, or a single liquid crystal panel,
with selectively configured conductor elements on the faces
thereof, and means for saturation driving of the conductor elements
in order to cause selected segments to exhibit discrete light
transmitting characteristics.
Inventors: |
Sherr; Solomon (Hartsdale,
NY) |
Assignee: |
North Hills Electronics, Inc.
(Glen Cover, NJ)
|
Family
ID: |
23288837 |
Appl.
No.: |
05/330,227 |
Filed: |
February 7, 1973 |
Current U.S.
Class: |
345/6; 349/77;
345/50 |
Current CPC
Class: |
G02F
1/1347 (20130101); G09G 2300/023 (20130101) |
Current International
Class: |
G02F
1/13 (20060101); G02F 1/1347 (20060101); G02f
001/16 () |
Field of
Search: |
;340/324R,324M ;350/16LC
;250/213A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Curtis; Marshall M.
Attorney, Agent or Firm: Eisenman, Allsopp and Strack
Claims
What is claimed is:
1. A multi-dimensional matrix addressing system, comprising an
assembly of liquid crystal units, each containing an array of
selectable segments which exhibit discrete light transmitting
characteristics in accordance with the presence or absence of
stimulation, said units being physically arranged relative to each
other to produce a predetermined relationship between their segment
arrays, first means for stimulating selected segments of a first
unit to exhibit one of said discrete characteristics, second means
for stimulating a greater number of selected segments of a second
unit to exhibit said one of the discrete characteristics, the
stimulated segments of said second unit being physically disposed
to correspond only partially to those selected in said first
unit.
2. A multi-dimensional matrix addressing system as defined in claim
1, wherein the selectable segments of said first unit are disposed
within discrete areas and the selectable segments of said second
unit are disposed within discrete areas of different configuration
than those of said first unit, only a limited number of the
stimulated segments of said second unit being physically disposed
in proximity to the stimulated segments of said first unit.
3. A multi-dimensional matrix addressing system as defined in claim
1, wherein the selectable segments of said first unit are disposed
within a plurality of discrete areas, said second unit being
divided into a corresonding plurality of discrete areas, the
selectable segments of said second unit being connected in groups
selectively stimulated by said second means, each group containing
segments disposed within a particular subarea of each of said
discrete areas.
4. A multi-dimensional matrix addressing system as defined in claim
1, wherein the selectable segments of each unit are disposed
substantially within a plane and the planes of each unit are
disposed parallel to one another.
5. A multi-dimensional matrix addressing system as defined in claim
1, wherein said first unit is divided into a plurality of discrete
rectangular areas, each containing said selectable segments; and
said second unit is divided into a corresponding plurality of
discrete rectangular areas, each of said areas being further
subdivided into a plurality of discrete rectangular subareas; said
second means being operative to simultaneously stimulate the
segments within the corresponding subareas of each discrete
area.
6. A multi-dimensional matrix addressing system as defined in claim
1, wherein said segments selectively exhibit a particular one of
said discrete characteristics in response to electrical
stimulation, and said first and second means selectively apply
electrical energy to said segments.
7. A multi-dimensional matrix addressing system as defined in claim
6, wherein said discrete characteristics manifest themselves as
modifications in opaqueness of said segments.
8. A multi-dimensional matrix addressing system comprising an
assembly of planar units disposed in face-to-face proximity, each
of said units comprising a plurality of liquid crystals; the liquid
crystals of said first unit being disposed in a plurality of
discrete areas, the crystals within each area being energizable by
a pair of conductors; the liquid crystals of said second unit being
disposed in a plurality of discrete areas, each corresponding to
those of said first unit and each being further subdivided into a
plurality of subareas, the liquid crystals within the corresponding
subareas in each area being simultaneously energizable by a pair of
conductors.
9. A multi-dimensional matrix addressing system as defined in claim
8, wherein said liquid crystals exhibit a particular one of said
discrete characteristics in rsponse to a voltage in excess of a
predetermined value, each said pair of conductors being energized
to apply either a positive or negative voltage to said liquid
crystals.
10. A liquid crystal assembly comprising at least two planar panels
of liquid crystal material disposed face to face; each panel being
provided with pluralities of conductors on each face thereof, the
conductors on opposing faces overlaying one another to define
discrete areas; means for energizing said conductors to selectively
create an electric field in said discrete areas to modify the light
transmission characteristics of the segment of said liquid crystal
panel in proximity thereto; the conductors of a first panel being
connected to modify the characteristics of only one of several
large discrete areas; the conductors of a second panel being
connected to modify the characteristics of selected ones of a
plurality of small subareas within each of several large discrete
areas, the large discrete areas of said first and second panels
being coextensive and in proximity; whereby said assembly exhibits
a single light transmission characteristic therethrough within a
sub-area defined by the particular sub-area and the large discrete
area selected by the conductors of said second and first panels
respectively.
11. A liquid crystal assembly as defined in claim 10, wherein a
voltage of predetermined magnitude is required between the
conductors on opposing faces of a panel to effect said modification
of the light transmission characteristics in the liquid crystal
material proximate thereto, characterized in that said means for
energizing said conductors comprises a first voltage source having
at least said predetermined magnitude and a first polarity,
selectively connectable to the conductors on one face of each
panel, a second voltage source having at least said predetermined
magnitude and the opposite polarity connectable to the conductors
on the other face of each panel, and means for selectively
connecting said voltage sources to all conductors except those
overlaying a predetermined sub-area.
12. A liquid crystal assembly as defined in claim 11, including
means for connecting the conductors overlaying said predetermined
sub-area to maintain a substantially zero potential
therebetween.
13. A liquid crystal assembly as defined in claim 10, wherein the
liquid crystal material normally exhibits a light transmissive
characteristic and exhibits a light scattering mode in response to
the application of an electric field.
14. A liquid crystal assembly as defined in claim 10, wherein the
liquid crystal material normally exhibits a light transmissive
characteristic and exhibits a light blocking mode in response to
the application of an electric field.
15. A liquid crystal assembly as defined in claim 10, wherein said
conductors are positioned to modify the light transmission
characteristics of sub-areas of said liquid crystal panels which
are arranged in rows and columns.
16. A liquid crystal assembly comprising a planar panel of liquid
crystal material provided with conductors on the opposing faces; a
conductor on one face substantially covering the entire surface; a
first plurality of conductors on the opposing face, each being
configured and positioned to represent a segment of the
alphanumeric characters in a particular font; a second plurality of
conductors on the opposing face, each being configured and
positioned to represent a predetermined opening between segments of
the alphanumeric characters in said particular font; said liquid
crystal material being operative to change its light transmission
characteristics in the area proximate to the field created between
conductors excited by a voltage of predetermined magnitude; first
voltage supply means for selectively applying a voltage having at
least said predetermined magnitude and a first polarity to the
conductor on said one face; and second voltage supply means for
selectively applying a voltage having at least said predetermined
magnitude and the opposite polarity to the conductors on said
second face which represent particular segments of the alphanumeric
character font to effect display of a desired character.
17. A liquid crystal assembly as defined in claim 16, in
combination with a second planar panel of liquid crystal material
having a second set of conductors positioned and configured in the
same manner as the conductors on the first panel, wherein said
first voltage supply means selectively applies the voltage thereof
to either the conductor on said one face of the first panel or the
conductor on the corresponding one face of said second panel, and
said second voltage supply means selectively applies the voltage
thereof to the conductors on the second faces of both said first
and second panels which represent particular segments of the
alphanumeric character font to effect display of a desired
character.
18. A liquid crystal assembly as defined in claim 16, including
means for selectively applying the voltage of said second voltage
supply means to said second plurality of conductors.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to multi-dimensional matrix addressing
systems; more particularly, it relates to multilayer display units
combining electrical, and/or other stimulation media of optical
addressing to effect display of selected data with a limited number
of active electrical inputs.
2. Description of the Prior Art
The use of electroluminescent panels as display media is well
developed. More recently, light emitting diodes, liquid crystals
and plasma panels have been used for the presentation of matrix
type displays. In general, a large number of input electrodes and
the switching positions are used in the prior art in order to
address all discrete points and achieve high resolution. The common
method of implementing activation of selected elements within a
matrix includes the use of orthogonal grid members which form a
matrix with a separate switching control for each grid line. Using
this arrangement, a unit of 256 elements or cross points would be
arranged in a matrix of 16 .times. 16. Thus, 32 switching or
driving elements would be required in order to achieve the desired
resolution. For a 1024 .times. 1024 array of 1,048,576 discrete
points, as many as 2,048 leads and drivers are required, in
addition to the necessary selection circuitry.
Various attempts have been made to limit the number of control
leads and selection circuit complexity, by using logic to reduce
the number of leads and active drivers. Two approaches of
particular interest are an electron beam display and a digitally
addressed solid state electroluminescent device. In each of these
systems, an approach to a theoretical minimum of active elements
has been indicated. In the first instance an evacuated envelope, a
complicated assembly of a large area cathode, and a multitude of
apertured multiplier plates are required. In the second instance, a
special photo conductor pattern is required which is difficult to
contruct and select.
In the electron beam display system, the apertured plates are
connected according to a binary code so that 20 plates are used to
achieve 2.sup.20 positions. One version of this device employs a
basic 7 .times. 5 matrix to generate alphanumerics at selected
locations. In this version, multiple beams are used to reduce the
number of plates, at a significant increase in the number of leads.
Non-vacuum tube versions of this arrangement have also been
described. They appear limited to binary coding and are based on
structures that are difficult to build and for which no performance
characteristics are presently available.
Still other attempts to circumvent the need for a multiplicity of
leads, are glow transfer mechanisms and various schemes devised for
plasma panels. The glow transfer arrangement operates in a single
dimension only and the plasma panels are encumbered with a complex
drive structure and elaborate electronics. No known satisfactory
technique for achieving a reduction that is applicable to a wide
variety of matrix displays has heretofore been proposed.
SUMMARY OF THE INVENTION
The multi-dimensional matrix addressing system of the present
invention is based on simplification of matrix addressing and
driving by adding additional dimensions to the standard two axis
planar panel approach. This is accomplished with a unique
combination of coupling and addressing modalities. The resulting
devices do not increase the complexity of the final unit nor do
they increase the number of coupling elements to a point at which
the cost is excessive as compared to the reduction in the
addressing and driving electronics.
A number of embodiments of the invention are described hereinafter,
wherein a multi-layer panel assembly employs electrical X-Y
coordinate addressing on each panel and optical coupling between
each of a plurality of panels. Photo conductor-electroluminescent
(Pc-E1) assemblies are used in one unit and matrix addressed liquid
crystal panels are used in another unit; the structures being
arranged such that the X and y conductors were patterned as taught
hereinafter by dividing the axes into a plurality of sections in a
particular manner. In other embodiments, polar coordinates may be
used, or if sepcific characters are to be displayed, selective
segment selection may be implemented.
The multi-dimensional matrix addressing system discussed herein can
be applied to most or perhaps all display elements, but the exact
form of the implementation is dependent on the characteristics of
the material used for the display element and also the manner in
which coupling is achieved between logic levels. Although the
following discussion relates to optical coupling between logic
levels, it will be immediately apparent to those skilled in the art
that other energy coupling means may also be utilized and governed
by the principles disclosed herein. In addition to
electro-luminescent panels with photo conductors as the optical
coupling medium, and the use of liquid crystals with passive
optical coupling, other materials such as gas plasma, light
emitting diodes, and ferroelectric ceramics are compatible with the
techniques described.
An object of the present invention is to produce a
multi-dimensional matrix addressing system using a minimum of drive
and selection inputs.
Another object of the invention is to provide a multi-dimensional
matrix addressing system which is both economical and practical to
fabricate.
Another object of the present invention is to provide a
multi-dimensional matrix addressing display system which can be
adapted toward the minimization of components with standard panels
utilizing various means for intercoupling adjacently disposed to
produce layered display media.
When employing the multi-dimensional addressing techniques of this
invention, one may utilize either active or passive coupling
between the various layers of a multi-layer display unit. Thus, one
aspect of the invention is embodied in a multi-layer photo
conductor electroluminescent assembly wherein the indication of a
cross-point selection in one layer is actively transmitted to a
second layer as a result of the luminescence of the selected
cross-point and its effect upon the adjacent photo conductive
material in the second layer. Another aspect of the invention is
embodied in a multi-layer liquid crystal panel assembly wherein
selection of a cross-point in a matrix is effected by placing all
other cross-points in a light scattering mode while leaving the
selected cross-point in a light transmissive mode. In this latter
embodiment, the cross-point selection might be considered to be
passively transmitted to the second layer, in that the selection of
areas or cross-points in each layer results in the creation of a
selected window or path for the unhampered transmission of light or
similar energy.
In accordance with the invention, there is disclosed a matrix
addressing system for panels containing an array of selectable
segments, each segment being operative to yield a discrete output
responsive to stimulation of several control elements. Two or more
of such panels are used. Means are provided for stimulating
selected control elements of the second panel, and coincidentally
stimulating a greater number of control elements of the first
panel; the selected segments of said first panel corresponding only
partially to those selected on said second panel, whereby only the
corresponding segments of the first panel produce said discrete
outputs.
In the particular embodiments described hereinafter, the coupled or
coupling means is light and the control elements are electrically
stimulated conductors arranged in a coordinate system.
A more complete understanding and appreciation of the invention
will be available from the following discussion which is made in
conjunction with the drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic illustration useful in describing the
principles of operation of the invention;
FIG. 2 is a schematic illustrating three principal layers of a
first illustrative embodiment of the invention;
FIG. 3 is a schematic illustrating the constituent parts of a base
layer of the illustrative embodiment shown in FIG. 2;
FIG. 4 is a schematic illustrating the constituent parts of the top
layer of the illustrative embodiment shown in FIG. 2;
FIG. 5 is a schematic illustration of a single layer in a second
embodiment of the invention, wherein passive coupling is
employed;
FIG. 6 is a schematic illustration of a further embodiment of the
invention wherein the principles of the invention are applied in a
multiplexing assembly to develop a display of alphanumeric
characters; and
FIG. 7 is a schematic illustration of yet another embodiment of the
invention wherein the multi-layer assembly is arranged in
accordance with a polar coordinate system.
DESCRIPTION OF A PREFERRED EMBODIMENT
Before describing particular systems of the invention wherein
multi-dimensional addressing is optimized by using electrical
addressing within a plane and optical coupling between adjacent
planes, a logical analysis of the problem is in order.
In the case of standard two-axis orthogonal addressing, an assembly
of 2.sup.2n elements may be arranged in rows and columns, each
containing 2.sup.n elements. In the worst case, these elements
would be driven with 2.sup.n.sup.+1 drivers. Each intersection may
be considered a two input AND gate for which the logic equation
is
P.sub.xy = P.sub.x P.sub.y (1)
where
P.sub.x = X axis enabling signal
X = 0, 1, 2, . . . n
p.sub.y = Y axis enabling signal
Y = 0, 1, 2, . . . n
In the system of this invention, the output of each intersection,
P.sub.xy, is coupled as a third dimension into corresponding
intersections of a further orthogonally addressed assembly. The
further assembly would similarly exhibit a logic equation:
P'.sub.xy = P'.sub.x P'.sub.y (2)
for each intersection.
By introducing the output of the preceding assembly, one develops a
three input logic AND gate described by
P'.sub.xyz = P.sub.x P.sub.y P'.sub.x P'.sub.y
where Z represents the third dimension, and P'.sub.xyz is the
output of this three input gate.
More generally this can be expressed
P'.sub.xyz = P.sub.xn P.sub.yn P'.sub.xn P'.sub.yn (3)
In a two level arrangement, equation (3) describes a logic gating
scheme wherein a first logic AND gate has coordinate section inputs
P.sub.x and P.sub.y yielding an output P.sub.z = P.sub.x P.sub.y ;
and a second logic AND gate wherein the output P.sub.z is ANDED
within additional coordinate selection inputs at a second level,
P'.sub.x and P'.sub.y.
The number of addressable points for the two level system will be
apparent from equations (1) and (3), but in algebraic form, while
the number of leads is given by
L.sub.t = L.sub.xy + L'.sub.xyz (4)
where
L.sub.xy = L.sub.x + L.sub.y
L'.sub.xyz = L'.sub.x + L'.sub.y + L'.sub.z
If the Z axis is achieved solely by means using leads, conductors,
and driver elements, there would be no advantage in the present
system. However, where the Z axis and the Z inputs are effected by
means other than leads and drivers, such as an electron beam or a
light beam, then a significant reduction in control elements is
possible. For example,
if P.sub.x = P.sub.y = P'.sub.x = P'.sub.y = 4
and L.sub.x = L.sub.y = L'.sub.x + L'.sub.y = 4
then P'.sub.xyz = 256 and L.sub.t = 16.
It will be seen that what might require 32 leads in a single gate
case requires only 16 leads in the two level case, assuming that
the third axis adds no leads or drivers. In general
then P.sub.n = (P.sub.x1 P.sub.yl) (P.sub.x2 P.sub.y2) . . .
(P.sub.xn P.sub.yn) (5) and the total number of leads is:
##SPC1##
where
P.sub.n = Number of points at logic level n
P.sub.x j = Number of x leads at logic level j
P.sub.y j = Number of y leads at logic level j
This is only one possible sequence and any combination of points,
logic levels, and leads is possible. The analysis defines the
conditions under which lead reduction can take place and can be
applied to any combination which meets the criteria. The first
described embodiment of the invention uses three levels and employs
light as the third coupled dimension. This embodiment demonstrates
the effectiveness of the system and makes clear its value if
applied with other physical coupling phenomena.
FIG. 1 illustrates three planar levels 10, 11, and 12 of a device
wherein each level comprises an array of areas or segments arranged
in rows and columns, each row and column being selectable by
electrically energized row and column conductors. The third level
is represented by a greatly enlarged portion corresponding to the
upper left portion of level 11 as defined by the heavy line 13.
With the three level arrangement of FIG. 1, one may select any one
of 4,096 points by energization of only 24 leads. In other words,
one need supply only the necessary logic circuitry and drivers for
24 leads as compared to the more conventional need for 128 leads
for driving a matrix unit of this capacity. It is essential, of
course, that the points of each level be coupled in such a manner
that adjacent sections of succeeding layers are enabled and
energized in accordance with whether or not the preceding section
has been selected. The operation of typical elements capable of
being employed in this type of matrix is such that energization
need not be exactly coincident in order to effect appropriate
operation; however, when using active coupling there must be an
overlap of enablement and energization.
The base level 10 is divided into 16 discrete areas arranged in
four columns and four rows. For purposes of discussion the
interconnected leads have been labeled X1 through X4 in order to
denote column leads disposed along an X-axis, and Y1 through Y4 in
order to denote row leads disposed along a Y-axis. The elements in
this level are selected by coincident stimulation of intersecting X
and Y leads.
The intermediate level 11 is also divided into a plurality of areas
arranged in rows and columns; however, the resolution of this level
is considerably greater than that of the base level. Level 11 has
been sub-divided by a multiple of 4 greater in both axes than the
base level 10. Accordingly, within the area denoted by selection
X1-Y1 in the level 10, there are 16 areas in level 11. The columns
and rows in level 11 are connected to four X-axis leads X'1 through
X'4 and four Y-axis leads Y'1 through Y'4. Each lead is connected
to every fourth column or row respectively.
If it is assumed that leads X1-Y1 and X'1 and Y'1 have been
energized, the double cross-hatched area in the upper left corner
of level 11 will have been selected. This selection by means of the
energization of four leads only, has effected a selection with a
resolution of 1 in 256.
The third level 12, depicted by a greatly enlarged segment, shows
representative leads interconnected in a manner similar to that
previously described. Lead designations have been made in
accordance with the same terminology as before, but using
double-prime notations, i.e. X"1 through X"4 and Y"1 through Y"4.
The resolution of this third level is four times that of the
preceding level in both axes. In order to select the upper left
hand element in this level, it is necessary to energize leads X1,
Y1, X'1, Y'1, X"1, Y"1. One has then effected a selection with a
resolution of 1 in 4,096 by the energization of six leads only.
Utilization of the 24 lead input to this device provides access to
the entire array of elements. The essence of this access lies in
the fact that each layer is coupled to the adjacent layers by means
other than electrical connection such that the selection of a broad
area energizes or enables the adjacent area which can then be
selected with increased resolution.
While the multi-dimensional matrix addressing system can be applied
to most or perhaps all display elements, the exact form of
implementation is dependent on the characteristics of the material
uSed for the display element and also the manner in which coupling
is achieved between each logic level. The embodiment illustrated
and described in conjunction with FIGS. 2-4, effects coupling
optically by utilizing electro luminescent panels with photo
conductors as the optical coupling medium.
FIG. 2 illustrates a number of separated layers including a base
layer 100, an adjacent central layer 200, and an upper layer 300.
These layers are designed such that selected areas of base layer
100 are electro luminescent in accordance with stimulation by
several conductive leads; intermediate layer 200 is basically a
dual layer element having a photo conductor material 201 on the
face adjacent to base layer 100 and an electro luminescent material
202 on the face adjacent to the upper layer 300. Upper layer 300
similarly has photo conductive material 301 adjacent to
intermediate layer 200 and an electro luminescent material 302 on
the face remote from intermediate layer 200. In an actual unit, the
illustrated layers are in close proximity. Although not shown in
FIG. 2, each layer is provided with conductive leads in the manner
discussed relative to FIG. 1. Thus, a discrete photo conductive
area of layer 200 is enabled by the light generated in the adjacent
selected electro luminescent area of layer 100. This enablement
permits a higher resolution selection and luminescence in the
electro luminescent area of layer 200 selected by energization of
the conductive leads associated with layer 200. Similar interaction
between layers 200 and 300, complete the selection of a
cross-point.
Several criteria are important in connection with this arrangement.
First, the photo conductive electro luminescent combination must be
capable of being selectively energized by the combination of
electrical and optical inputs provided. These elements are provided
with patterned conductors on both sides oriented such that
individual points may be electrically energized. In the embodiment
of FIGS. 1-4, the orientation is in the form of orthogonally
disposed rows and columns; however, other arrangements are within
the scope of the invention and may be desired depending upon the
particular type of display being effected. It is of course
necessary that there is sufficient light energy from the electro
luminescent layers to enable the photo conductive layers to be
driven to the low resistance state as selected intersections of the
conductors are stimulated. It is also necessary that the electro
luminescent layer at the output end of this array develops a
sufficient light output to either be viewed directly or to drive
subsequent devices which will generate the desired display.
Finally, there must be sufficient speed of response in the photo
conductive layers such that more than one group of points can be
addressed at acceptable refresh rates.
In a particular embodiment of the invention, the structural
configuration suggested by FIGS. 2-4 was employed.
The base layer shown in FIG. 3 had an active area of 1.28 inches by
1.28 inches, electrode in order to bring out two X selected
segments and two Y selected segments. Such an element would
correspond for example to one-quarter of the layer 10 shown in FIG.
1. Thus, four leads were provided which would excite any selected
quadrant of the base layer panel. The layer included a substrate
110 of glass or similar nonconductive material; aluminum grid lines
111 deposited upon the glass substrate for a length of 1.28 inches
and having a width of approximately 0.64 inches; electro
luminescent phosphor 112 applied over the aluminum; and a
semi-transparent gold electrode 113 evaporated thereover. The gold
electrode was scored down its center at right angles, as
illustrated by gap 115, in order to develop the four individually
addressable elements of the four quadrants. In order to protect the
gold conductive layer, a thin mylar cover 114, or the like, may be
deposited thereover. There is thus provided the electro luninescent
layer 112 having conductors 111 and 113 orthogonally disposed on
opposite sides thereof. This layer is energized by selective
excitement of the coordinate energizing leads and due to the
transparency of the upper metallic conductor, the luminescence may
be employed for excitation of an adjacently disposed intermediate
layer.
The center and upper layers of this illustrative embodiment of the
invention comprise both photo conductive and electro luminescent
materials and accordingly are somewhat more complex than the base
layer. A typical upper layer 300 is shown in FIG. 4. This layer is
fabricated upon a non-conductive substrate 310 of glass or the
like. Molybdenum conductive strips are laid or etched upon the
substrate 310 and the photo conductive layer 314 is deposited above
these strips. An additional layer of clear non-conductive material
such as glass 316 is thereafter applied and bonded by layer 315.
Glass 316 has apertures corresponding to the cross-points of the
unit, and its upper surface is blackened in selective areas 318 to
prevent the passage of light. The upper conductor is provided in
the form of a conductive epoxy 317, also disposed orthogonally. An
additional glass layer 319 is provided, which is perforated by the
desired number of apertures for transmission of the photo
conductive effect through to the electro luminescent layer which is
deposited at 320. A semitransparent gold layer 321 is then
deposited as described above, and a mylar cover 322 completes the
fabrication. One thus has developed a cell having sandwiched
therein a plurality of photo conductors and electro luminescent
areas with apertures interconnecting the photo conductors as
required, these apertures being interconnected electrically in
order to selectively energize the photo conductive areas when
enabled by illumination from the preceding electro luminescent
elements which then effect illumination of the associated electro
luminescent layer.
In a particular embodiment, the top layer was provided with 32
apertures or cross-points of the type shown in FIG. 4, in each
axis, for a total of 1,024 cross-points. The intermediate layer was
fabricated in an identical fashion with the difference that the
insulators 312 separating the photo conductive layer occurred only
every fourth row in both the molybdenum and gold electrodes. Thus,
the resolution of the intermediate layer was 8 .times. 8 or 64.
FIG. 5 illustrates another embodiment of the invention utilizing
liquid crystals. Two criteria essential for such embodiment are
that it be capable of being used in a matrix addressed assembly and
that a plurality of layers may be arranged in tandem without
excessively reducing the contrast ratio between transmissive and
scattering portions of the unit. In this embodiment, one may also
use orthogonal selection of cross-points; however, the optical
coupling is passive rather than active. Selection of the
intersecting conductors in such a system will render the selected
cross-point area light scattering, light blocking, or light
transmissive, depending on the type of liquid crystal optical
effect employed.
In the operation of this particular embodiment, all rows and
columns in a first layer, with the exception of the ones containing
the information cross-point, are addressed and put into the
scattering or light blocking condition. The lower layer is
thereafter addressed so that the row and column containing the
information cross-point is not activated and remains transmissive.
The transmissive state will also exist for the intersection of the
rows and columns connected to the selected row and column, but only
the intersection of the selected row and column will be under the
transmissive area in the top layer. As a result, only one
cross-point or area will be fully transmissive, with all others
having either one or two scattering or light blocking layers.
FIG. 5 discloses a top panel 500 and bottom panel 550, side by
side. Actually, these panels are assembled with their surfaces in
proximity. For purposes of illustration, the top panel is arranged
with four columns 501, 502, 503, 504, and four rows 511, 512, 513,
and 514. Energizing leads associated with each column and row are
actuated by a Selection Circuit 510, 520 respectively. Bottom panel
550 is similarly arranged; however, it is connected to the
Selection Circuits to effect the higher resolution discussed above
in connection with FIG. 1.
The Selection Circuits are designed to energize all leads except
those connected to the column or row to be selected. Column
Selection Circuit 510 applies a voltage (+)V to the leads and Row
Selection Circuit 520 applies a voltage (-)V to the leads, where V
is the voltage magnitude required to place the liquid crystal
material in its light scattering mode. As a result, all areas of
panel 500, with the exception of the desired cross-point, will have
a voltage of magnitude V or 2V applied across the liquid crystal
material. Thus, only the area at the desired cross-point will be
light transmissive.
The driving and selection technique just described, which operates
on the saturation voltage, rather than the breakpoint voltage, may
be used with field effect units wherein the analyzer-polarizer
combination is arranged to cause light transmission in the
non-activated mode. This type of unit is quite insensitive to
voltage variations and consequently cross talk is minimal. Normal
break point X-Y addressing may also be used when the
analyzer-polarizer combination is arranged to effect light blocking
in the non-activated mode.
For purposes of clarity and to avoid obfuscation, the system has
been disclosed in conjunction with row and column arrangement of
elements and conductors in order to provide a square array,
however, the system of the invention is not limited to such a
configuration of electrodes and elements. Depending upon the
display desired one may arrange the electrodes more optimumly for
achieving a display of alphanumeric characters, graphs and charts,
or other formats such as range-azmiuth displays.
FIG. 6 illustrates use of the saturation voltage technique for
multiplexing a group of segmented characters. The individual
character segments, numbered 1 through 9, are connected by leads to
a Segment Selection Control Circuit 600, which is operative to
energize the selected segments by a voltage (+)V and to connect all
other segments to ground. In the FIGURE, two character positions
are illustrated, but of course, others may be similarly connected.
The common electrodes for the character positions are connected by
leads to a Position Selection Control Circuit 650, which is
operative to return the electrode in the selected position to
ground, while all other common electrodes are returned to (-)V.
Thus, all areas will be fully activated except in the selected
positions and the character will be viewable in that position only.
Therefore since all equivalent segments in each position are
connected in parallel, the multiplexing may be achieved with only
one lead per character segment plus one lead per character
position. With respect to both FIGS. 5 and 6, reference has been
made to voltages (+)V and (-)V. It should be appreciated, that one
may also achieve the desired effects, by using other forms of
energy than direct voltage. For example, pulses of appropriate
magnitude may be employed. Still further, alternating current of
appropriate magnitude may be used if the relative phase of the
voltage applied by the various control leads, is properly
adjusted.
FIG. 7 illustrates the use of these techniques in a polar
coordinate display of the range-azimuth type. A typical layer is
divided up into angular segments .theta..sub.1, .theta..sub.2,
.theta..sub.3, .theta..sub.4, and radial segments e.sub.1, e.sub.2,
e.sub.3, e.sub.4. Several layers of differing resolution may be
used. Such an assembly operates by addressing all rings and sectors
except those in which the selected area falls. This leaves the
selected area light transmissive. Of course, the voltage applied to
the leads must be large enough to cause light scattering in the
connected elements.
A number of embodiments of the invention have been shown and
described. All modifications and developments of the teachings
herein, which are within the skill of those in the art, are
intended to be covered by the following claims.
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