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.

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.

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.