EP0478621A1

EP0478621A1 - Color display system using thin film color control

Info

Publication number: EP0478621A1
Application number: EP90909267A
Authority: EP
Inventors: William F. Glick
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-06-17
Filing date: 1990-06-13
Publication date: 1992-04-08
Also published as: EP0478621A4; WO1990016057A1; JPH05504002A; CA2059135A1

Abstract

Un système d'affichage panchromatique à couche mince à haute résolution est formé (1) de zones discrètes d'une couche métallique (40) à épaisseur calibrée enrobée d'oxyde anodique, couplée à une sur-couche en dioxyde de silicium pour la protection et à une sous-couche conductrice transparente, afin d'assurer un affichage de forte intensité de couleurs sélectionnées sur lesdites zones avec une sélection de pixels à haute résolution monochromatique et/ou à plusieurs couleurs et (2) d'un activateur d'éclairage de fond à haute résolution qui comporte des rangées x et y d'électrodes minces (22, 24) recouvrant une couche mince de matière photovoltaïque (26) et construit pour servir de matrice de filtre de lumière ou bien directement de matrice de source de lumière, une rangée de ces électrodes (25) pouvant coïncider avec lesdites zones.A high resolution thin layer panchromatic display system is formed (1) of discrete areas of a calibrated thickness metallic layer (40) coated with anodic oxide, coupled with a silicon dioxide overlay for protection and to a transparent conductive underlayer, in order to ensure a display of high intensity of selected colors on said areas with a selection of pixels with high monochromatic resolution and / or with multiple colors and (2) of a lighting activator. high resolution background which has rows x and y of thin electrodes (22, 24) covering a thin layer of photovoltaic material (26) and constructed to serve as a light filter matrix or directly as a light source matrix , a row of these electrodes (25) possibly coinciding with said zones.

Description

COLOR DISPLAY SYSTEM USING THIN FILM COLOR CONTROL

BACKGROUND OF THE INVBNTION

The present invention relates to the field of display systems and affords the basis of a new technology and new commercial prospects in such field.

The portions of the field of display systems and of other fields addressed by the present invention include consumer, and industrial video, projection video, military and scientific, display panels, color filter controls, and light sources. The term "display" as used herein includes displays and display-like systems, unless otherwise indicated.

The state of the art of display systems includes gelatin or dyed polymide filter materials associated with matrix light source means with intensities of display-transmission (as a percent of source light) of about sixty for blue-green spectral ranges and ninety for red. For a good review, see, e.g., Latham et al., "Color Filters From Dyed Polymides" Solid State Technology (May 1988). The state of the art also includes active matrix liquid crystal display (LCD) means. See, e.g., Sakai et ali. (NTT), "A Defect-Tolerant Technology for An Active-Matrix LCD Integrated With Peripheral Circuits" SID (Society for Information Display) 88 Digest pp.400 - 403. thin film diode or transistor light emitter arrays can be provided in similar fashion, The foregoing publications are incorporated herein by reference as though set cut at length herein. The present invention provides significant benefits compared to the state of the art and commercial practice thereof.

It is an object of the present invention to provide displays of high resolution dot area (pixel) selection, with high intensity of color availability selectable over a large spectral range in custom tailored design and production.

It is a further object of the invention to provide eighty five percent-plus (preferrably, over ninety percent) light intensity throughout the visible optical spectrum (including red, blue, green) and preferrably also in technical spectral ranges beyond visible (e.g., near IR, far IR, uV).

It is a further object of the invention to provide such displays of compact structural form.

It is a further object of the invention to provide such displays with long life and low failure vulnerability.

It is a further object of the invention to provide such displays economically and simply.

It is a further object of the invention to provide such displays with high speed of response to control signals and simply control means in combination therewith. It is a further object of the invention to provide such display free of parallax and/or anisotropy limitations of its optical characteristic.

It is a further object of the invention to provide such display with a high degree of temperature stability and/or chemical stability under all conditions of manufacture and use.

SUMMARY OF THE INVENTION

The objects of the invention are realized in a system using thin film technology to provide a key color control section and also using such technology for light control steps other than color filtering.

The display system has a light source and high resolution light control filter producing selected dots of light origination or passage at high resolution (or dots of light blockage in an ambient of essentially collimated light).

In its light passage embodiments, the system is constructed and arranged so that a beam of light impacts a thin film color control panel and passes through it (or is reflected by it), and preferrably also passes through a protective transparent screen, to a viewer. The color control panel comprises a highly adherent color response material, preferrably an anodically oxidized thin film of tantalum or tantalum nitrides or other anodically oxidizable metal (valve metal).

Preferrably, the color control and light control filter portions are integrated to some extent as hereinafter described to afford automatic self-alignment of cross-hatched (e.g., x-, y- ) electrodes to define an array of cross-overs, automatically slaved in correct array positions. Dots of light are praduceable at the cross-overs to yield controlled 'pixels' as small as a single dot or with a group of dots (a few or many) defining each pixel.

In accordance with the invention selected areas of the tantalum oxide (preferrably adjacent stripes in a set, with an array of repeating such sets of stripes) are of different thicknesses to produce different color responses to incident/transmitted light. According to a further aspect of the invention the tantalum oxide "layer" has internal sublayers of tantalum oxide and a transparent material, e.g., silicon dioxide. There can be multiples of such sublayers stacked over each other to enhance the brilliance of color response, according to a further aspect of the invention.

The color control elements are (preferrably) side by side in a single thin film layer or in each of several such sublayers thereby affording high intensity. The general illuminating light passing through color bands of the control layer projects over a wide angle space after passing through the color layer with anisotropic optical response, i.e. over 90' (preferrably over 135') of viewing angle. The tantalum oxide film, or the like, is very stable and resistant to severe conditions of temperature and/or acidic or alkaline environment. It is formed by anodic oxidation using an underlayer of transparent thin film metallic coating of the metal itself as an anodic electrode. The metal may be supplemented by a thickening layer of electrically conductive, transparent material for optimum resistivity in end use.

Where the anodic oxide separates x-, y- electrodes or the like (as indicated above for preferred embodiments) then a very high dielectric constant separation of such electrode groups can be formed with high electrical insulating value, but accommodating close spacing.

Other objects, features, and advantages will be apparent from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawing in which: BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an isometric sketch of an embodiment of a display system of the invention;

FIGS. 2 and 3 are lateral and transverse cross-section sketches (taken at the respective viewing directions H-H and III-III of FIG. 1) oN an expanded scale, of a portion of the FIG. 1 embodiment;

FIGS. 3A, 3C and 3D are sectioned sketches, further expanded and highly schematic illustrating steps of construction of a portion of the color control section (and a part of the pixel selection section) of the FIG. 1 embodiment and FIG. 3B is a flow chart outline of those construction steps (note that there is a change in construction in FIGS. 3A╌ 3D compared to FIG. 3 wherein the separate y- electrodes of FIG. 3 are emitted and replaced by y- electrodes integrated with color stripes in FIGS. 3A, 3D);

FIG. 4 is an expanded face view of the glass substrate (screen) of the FIG. 1 embodiment indicating selectively established dots of light passage and blockage and a single pixel arbitrarily established as a nine dot by nine dot square (although a pixel could be established much larger or as small as a single dot);

FIGS. 5-7 are similar face views for other embodiments of pixel determination on the display screen;

FIGS. 8A and 8B are diagrams of usage of the color filter of the display system without high resolution areas segregation, but rather as a broad area color control filter in transmissive (8A) and reflective (8b) modes;

FIG. 9 is a sectioned sketch (taken laterally as in FIG. 2) of a variation of the FIGS. 1-8B embodiments using buss bars to reduce resistivity losses along the elongated conductors; and

FIG. 10 is a related circuit diagram.

FIG. 11 is a trace of decreasing sheet resistivity of an indium-tin-oxide coating as enhanced through an aspect of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring new to FIG. 1, there is shown an embodiment of the invention comprising a light source 10; a light passage section 20; and a display screen 30 with a color defining back coating 40 (at the interface-planar region between 20 and 30) hereinafter described. As variants from this embodiment, (a) the light source can be set lack at a distance or (b) the light source and light filter can be integrated in various ways as explained below. The viewer's position is indicated at E. The elements 10, 20, 30 are preferrably of contact slab-like form and can each be made in thicknesses substantially below an inch. FIG. 1 also shows that the section 20, which is electrically controlled has x-electrodes 22 and y-electrodes 24 in the forms of arrays of linear conductors in spaced parallel planes (one plane for each array). When electrical current is supplied to one x-electrode conductor 22 and one y-electrode connection 24, the current of such active conductors is controlled (taking into account voltage drops along the lengths of such elongated conductors) so that a voltage is supplied to an essentially tubular cross over spot.

The light source 10 preferrably comprises a full spectrum, level intensity source, but in specialized applications (or for economy) may be of narrow spectral range (within or outside the visible range) or with unusual intensity or attenuation at particular wavelengths. She light source material choices can be electroluminescent, incandescent, fluorescent, or other thermal, photovoltaic or discharge means.

FIGS. 2 -3 show the light pass element 20 expanded side and top view sections of the FIG. 1 arrangement comprising wires (or striped coatings or other equivalents) 22 and 24 for x- and y- electrodes, respectively. The electrode wires or stripes are of fine diameter or span and sandwich a photovoltaic liquid crystal material 26. When crossing x- and y- electrodes are active at a crossover material spanning point, the local material is activated to pass or block light (depending on the selected material) to produce a high resolution spot of light passage (or blockage) of no higher than .005" × .005" or as low as .0001 inches × .0001 inches, preferrably about .0005 to .001 inches (.0125 to .025 mm; 1/2 to 1 mil) × .0005 to .001 inches, or circular equivalents. Generally, for uniform spacing of x- and y- electrode arrays the spot will be in-between ideal circular and square configuration (an approximate square with rounded corners). But essentially perfect squares or circles of light passage (or blockage) can be produced with specialized electrode/light-control-material combinations, or elongated spots can be produced, using artifacts well known to those skilled in the art of high resolution displays.

FIGS. 2 - 3 and 3A also show the glass display screen 30 and its color defining back coating 40 affording a protected, high resolution color defining system. The screen can be made of various forms of glass or glass equivalents suited to various applications, including transparent or translucent plastic and ceramic plate (or mesh) materials. The coating 40 can comprise (e.g., as in the FIG. 2 - 3 embodiment) a base 42 of tantalum and an overlayer 44 of anodically formed tantalum pentoxide, in turn overlaid with a protective coat 46 of silicon dioxide. The coating 40 preferrably comprises (e.g., as in the FIG. 2 - 3 embodiment taken together with FIGS. 3A╌3D) a transparent base portion 25 of, preferrably, about 3,000 Angstroms thick indium/tin oxide which is controllably coated on the screen 30 (or onto a temporary substrate and then transferred to the screen). The coating method is preferrably sputtering (under preferred conditions of 1 × 10^-5 Torr pressure (with a partial pressure of six microns of oxygen in a background of inert ambient gas) , one thousand volts, 1.5 amps discharge, sputtering an indium/tin mixture cathode target with deposition conditions adjusted to give about five ohms per square sheet resistivity indium/tin oxide. Such indium/tin oxide systems per se are well known and characterized in the display arts. They are transparent in the full visible spectrum and have controllable electrical resistivity/conductivity further conditions. The indium/tin oxide is overcoated with a thin layer 42 of tantalum nitride, preferrably on the order of 1,000 Angstroms and applied by vacuum deposition, sputtering or electrolytic molecular beam epitaxy (MBE) . The tantalum nitride is then anodically oxidized to form a layer 46 of tantalum pentoxide at a thickness effective as a blue filter. Interval stripes 261 are etched in the coating 40 dcwn to the glass level. The remaining isolated metal/metal oxide stripes 46G and 46R are then oxidized to differing oxide thicknesses of adjacent such stripes, in a repeating series of sets of graded tantalum oxide thickness ╌ yielding different color responses corresponding to tantalum oxide thicknesses indicated as oxide stripes 46R, 46G and 46B (typically with combined tantalum and tantalum oxide thicknesses of about 1,600, 1,400 and 1,200 Angstroms respectively, based on an original 1,000 Angstrom tantalum film, to define red, green and blue responsive stripes, respectively) . The isolated strips 42/25 are available as anodic electrode conductors to form stripes 46G and 46R to green and red. By "response" or "responsive" to a given color we mean that the stripe will pass that color spectral component of a light source. The three adjacent stripes 46R, 46G, 46B define a set 46S which is one of a series of many such sets spanning the coating to define a full display area.

It will be noted that in the FIG. 2 - 3 embodiment separate y-electrodes 24 (preferrably of optically transparent, but electrically conductive material such as indium/tin oxide, I.T.O. ) for light passage element 20 and tantalum stripes 26 are provided (as anodic electrodes and, ultimately, as color filters). There is a problem of aligning electrodes 24 and 26 which can be overcome. It can also be avoided. As shown in FIG. 3A, I.T.O. stripes 25 (or a full base layer before etching in the stripe intervals 261) can be provided under the tantalum layer(s) 42 to enhance conductivity thereof for service as y-electrodes of element 20 thereby resolving alignment problems.

The anodizing (oxidation) conditions comprise a series of anodizing steps at different voltages applied to the sheet of indium/tin oxide overlaid with tantalum (acting as an anode) and a distant counter-electrode (cathode) to produce the respective stripes, under anodization conditions and controls, as well as criteria, well known in the electrochemical arts, including - preferrably, for present purposes - use of citric acid aqueous electrolyte. conventional high resolution masking techniques may be used to protect stripes not to be treated in a particular step. However, it is preferred - when interval stripes break up the indium/tin oxide stripes - to use the indium/tin oxide base layers as selectively activated electrodes (or simultaneously activated at different voltage levels) to facilitate anodization.

The preferred normal process, as indicated in FIG. 3B (for construction of an integrated y-electrode color control stripe array), is to coat the glass with I.T.O.; then coat with Ta₂N; then anodize to blue transmit; then to etch interval stripes (using conventional photo lithographic processing including a masking step to create precise, reliable alignment and width control of intervals and remaining raised stripes); then anodizing green transmit and red transmit stripes; then depositing photoresist protection mask over the three colors, leaving interval stripes between color stripes clear; and then depositing opaque material over the entire plate. Finally, one lifts off unwanted opaque material and remining photoresidue. Thus the adjacent stripes of a resultant set are separated by high resolution opaque interval segments. Alternatively, high resolution interval defining mask stripes can be applied to the coating at any other stage of development. Such intervals, when used, provide the opportunity for sharper relief (contrast) to colors.

FIGS. 3 and 3A provide expanded illustraticn of the above described striping using intervals between color stripes of an RGB set and between sets. 3he glass screen 30 is of twentyfive to forty mil thickness depending on total size of display for rigidity and coated with repeating sets, each comprising three stripes 46R (red), 46G (green), 46B (blue), separated by intervals 461. The latter nay be bare or backfilled with an opaque material. The intervals preserve electrical separation of stripes 26R, 26B, 26G as well as visual distinctness of such color stripes. As noted above, the stripes are thin films with multiple layers. The width span of each of stripes 26R, 26G, 26B is about .005", preferrably e.g., .001" for use at present industrial goal levels in the consumer TV field practice (being .015"); but, for other applications, e.g. HDTV, the width can be set as lew as .0001"-.0002"). This is relatable to selected spot sizes of the light filter section 20 and desired display screen color resolution and/or desired pixel size, as a whole, for the end use display, all as discussed further, below. The stripe width is preferrably uniform, but may be non-uniform for some applications. The interval stripes are from twenty to one hundred fifty percent of adjacent color stripe widths (taking an average where adjacent stripes are of different widths). Of course, the interval stripe can be made smaller or emitted (i.e., under ten percent of adjacent active stripe width).

FIG. 3A also shows the associated light source 10 produ cing a uniform, preferrably collimated light output L1 and electrically controlled filter section 20 (typically about ten to forty mils, i.e., .010-.040 in. range) producing selectively passed large or small spots of light 12. As noted above, the reverse strategy can be used, i.e. selective blockage. Large spots of light passage (or blockage) are composites of adjacent small spots of such passage (or blockage).

As mentioned above, FIGS. 3A (and FIGS. 3C-3D) also show a further embodiment of the invention wherein light source and control are combined as shown at 10/20-EL using an electroluminescent material (or other artifact, e.g., an array of semiconductive light emitting diodes or light emitting phosphors). The electrode strips 22, 25 provide the crossing x-, y- activitatiαn matrix for selective light emission.

Preferrably, a silicon oxide layer (not shown) of about 1,000 Angstroms of thickness is deposited over the tantalum oxide stripes by sputtering or chemical vapor deposition, for protection with minimal light attenuation. Sequential layers of Ta₂O₅ and S₁O₂ i.e., several "sets" each typically two or three may be added to enhance or "peak" the transmission percentage and provide brighter response. This is shown, as applied to stripes 26B, 26G in FIG. 3D with tantalum repeats 42-1, 42-3, 43-3 and tantalum oxide repeats 44-1, 44-2, 44-3.

FIG. 4 is a face illustration of stripes of adjacent color sets overlaying the high resolution filter defined as x-, y- array of activatable light passage (or blockage) spots. The x- and y- electrodes (22, 24 in FIG. 1 or 22, 25 in FIG. 3A) of light filter 20 enable uniform controlled spots 20L of selectable light passage or blockage. These can be of essentially circular form of, say, .0001 inch diameter with minimal overlap, if any, of adjacent spots. The stripes 26B, 26G, 26R of a set 26S can be of .0002 inch width with interval stripes 261, between stripes of a set and between adjacent sets, of .0001 inch width, to produce a single set color span width of .0009 inch. For purposes of FIG. 4, the use of spots 20L aligned with opaque interval stripes 261 is assumed; these are, of course, superfluous and can be omitted in high volume production designs (or at least electrical controls for such cross-over locations can be emitted or set at a default light blocking mode as shown in FIG. 4).

The x-, y- electrodes can be controlled with a pixel strategy of uniform size pixels of width of one or more dots (crossovers) or sets of dots and height of one or more dots or sets of dogs in integral or non-integral units. Each such pixel as arbitrarily defined has a selectability of spectral and intensity choices, through selective passage or blockage of light in selected amounts (numbers of spots activated) through color bands defined by the stripes.

The usual term 'pixel', as a .fundamental unit of display resolution is an arbitrary construct as applied to the present invention (though corresponding to a physical spot in a raster scan cathode ray tube, light emitting diode matrix, discharge tube matrix, incandescent lamp matrix or like state-of-the-art displays). Accepting the conventional term pixel arbitrarily, as applied to FIG. 4 and defining a pixel width EW as one set width and pixel height IS as a height equal to that width, then a .0009" × .0009" pixel is established (i.e., about one mil × one mil). This say be compared with the so called high definition television standard pixel, which - in most currently commercial or proposed-as-commercial embodiments has a pixel of eight to ten mils × eight to ten mils width/height dimensions; NTSC (U.S.) conventional television (in home sets) of about thirty mils × thirty mils; or projection television systems of sixty to eighty mils × sixty to eighty mils. State of art CRT computer monitors use fifteen mil × fifteen mil pixel standard and state of the art LCD computer monitors use a twenty-five mil × twenty-five mil pixel. Even if the FIG. 4 embodiment is derated by a factor of five times (i.e., to a five mil by five mil 'pixel'), it still exceeds state of the art resolution. Moreover, the distinct pixel limitation can be avoided in the present invention, with a computer controlled x-, y- electrode control affording interleaved pixels (or to put it another way referring to the spots 20L as the fundamental units of resolution).

Staying with the example of a FIG. 4 as defined above and assuming each spot 20L to be normally light transparent when not activated and opaque (as shown by shading-in in the figure) when activated by a voltage applied from its crossing x-, y- electrodes (the blocking strategy), then it is seen how color is constructed for the 'pixel' of PW/PH width and height (.0009" × .0009", or nine spots × nine spots, 20L as previously defined). Hatching across selected spots in FIG. 4 indicates controlled blocking:

╌ of all spots aligned with the vertical interval stripes, as a complement to, or in lieu of, opaque materials of the stripes per se, for contrast;

╌ some of the red vertical stripe's spots;

╌ none of the green vertical stripe's spots; and

╌ all of the blue vertical stripe's spots.

The net effect is a predominantly green pixel of maximum intensity with a contributed red component of about forty percent maximum intensity which a human viewer (or machine imaging viewer of human resolution and perception capacity, more or less) detects only as a composite color. This together with dozens, or hundreds of adjacent controlled pixels provides the viewer color impression. It will be appreciated that apart from intensity control, there is a high redundancy of color selection signals imposed on a single 'pixel' to assure reliable response even in the event of partial control system failure.

FIGS. 5 - 6 show other variants of pixel control (in face view as in FIG. 4, but with dots indicated as rectangles). Both embodiments have a one spot pixel. In FIG. 6 interval striping 461 is shown. In FIG. 5 the array of y- electrodes (undercoat component 25 of stripes 46 in FIGS. 3A - 3D) and/or X-electrodes (22/FIGS. 1 - 3D) may have to be thinned down to avoid shorting of adjacent such electrodes, e.g., a .0035" conductive electrode width in relation to a .005" color stripe.

In FIGS. 5 and 6 red, green and blue alternate in 1:1:1 relation in the stripes 46R, 46G, 46B. But it will be understood that other ratios can be provided. For example, human observation favors repeating multiples of 4:2:6 of blue:green"red, respectively, for optimum control. This kind of balanced ratio can also be used to compensate for variances in phosphor (or LCD) or lamp spectral range or quality in the light passage/blockage/origination sections of the display system.

FIG. 7 shows another such embodiment with a horizontal stripe width 22 equal to the aggregate of five vertical electrode stripes 25 and associated intervals 251 (all buried in a single color stripe layer 46B/blue). Activation of a cross-over pair (one x- electrode, one y- electrode) will light up (or block light) in ten dots, if the conductive strips 25 are ganged or shorted. Alternatively separate electrode connections can be made to 25-1, 25-2, etc. for more precise control. FIGS. 8 and 8B show usage of the color control section without striping or other areal configuration, used simply as a filter in transmission (8A) and reflective (8B) modes.

FIG. 9 shows (in transverse section, as in FIG. 2) a display system where the y- electrodes 25 (see, e.g., FIG. 3A) are provided with buss-bars, e.g. B(Y) , at intervals to establish low resistance path lengths to all regions of the y- electrodes and in turn to each dot defined by a cross over of such a y- electrode with an x- electrode 22. Similar strategy can be provided for electrodes 22. The resultant equivalent circuit is shown in FIG. 10 where sections of anodic oxide coatings 44 together with crossing-over x-, y- electrode portions 22, 25 act as an array of capacitors. The insulative value of the anodic oxide is supplemented by that of the phosphor electroluminescent layer.

Thin indium/tin oxide layers can be used for transmissiveness but using the buss bars to limit voltage drops along electrode lengths.

The control of spot selection and presentation of a screen display can (advantageously) be simultaneously implemented over a whole screen (or large section of a screen) ╌ in contrast to a raster scan or like rolling implementation of display control. But rolling implementation can be administered in the present case for some aesthetic reasons and/or to utilize salvaged control equipment.

While color control in terms of primary colors of additive synthesis have been described, other repeating color stripes of additive or substractive synthesis systems can be applied. The available range of colors can be constantly varied from section to section of a display. Control systems utilizing the above display formats can comprise use of one or more of the following exemplars, extrapolations therefrom or equivalents or extensions now apparent to those skilled in the relevant display art, given benefit of availability of the present invention and its disclosure herein.

The display system can be made in selected small or large sizes with uniformity of performance unlimited by edge or corner effects of the types associated with CRT displays or the like. Resistance over lengths of x-, y- control electrodes can be a limitation at very long lengths (e.g., several hundred light spots length); but this can be circumvented by modular construction of the filter portion and/or use of (preferrably transparent) buss bars overlapping the filter electrode wires to carry higher voltage nodes to the interior of the filter area. The glass 30 (or a precursor transfer substrate) can be of indefinite length in manufacture or made in convenient batch sizes and cut to end-user sizes as needed. The basic filter construction is similarly flexible as to economical stock manufacture and custom selection of usable sizes.

Several variations have been discussed above relative to a core embodiment. Several further variations can be made consistent with the scope and spirit of one or more aspects of the present invention. For example, color control materials other than tantalum pentoxide can be used ╌ e.g., oxides of other valve metals affording an adherent film.

The indium/tin oxide stripes, or equivalents, are usable for their optical properties and for their electrical properties (carrying current to provide a monolithic anode electrode or distinct anodes in the anodic oxidation step) and mechanical properties as a glass to tantalum substrate bridge, all as shown above. But further, in end use, indium/tin oxide stripes can be used as electrodes to control response (and/or on-off response) of overlying coating layers.

The basic color stripes (and interval stripes, when used) are shown above as arrays of long stripes in a single direction. But cross etching, after a need for electrical continuity has passed and using appropriate masking or selective etching can produce lands (isolated mesas or islands) of color responsive oxide spots.

The light source spectral range and intensity and/or glass screen transparency characteristics are further distinct variables controllable in design selection or utilization to further impact a display.

While x-, y- orthogonal coordinates are shown above for filter electrode arrangements, one could use various nonorthogonal coordinate systems, e.g., polar coordinates. A variety of linear or non-linear increments (e.g., logarithmic) can be imposed in each coordinate set.

The areas of application of the invention include - but are not limited to - consumer and industrial video, computer monitors, instrumentation displays, military displays, sports arens scoreboards and other variable public billboards. The invention is also utilizable as a controlled light source independent of display purposes in sizes ranging from very small to very large, taking advantage of one or more of the flexibility off control control, resolution, economy of manufacture and/or other aspects of the present invention.

The invention also comprises means for enhancing the conductivity of the indium-tin-oxide underlayer or overlayer material (where used) and resultant enhanced indium-tin-oxide product (a coating) and enhanced coated product. This aspect of the invention can be applied to materials for electrical conductivity compatibly with high light transmission.

Through this last-mentioned aspect of the invention, sheet resistivity an the order of below 2.0 (in some instances, below 1.0) ohms-per-square is achievable compared to five to fifty ohms-per-square in the state of the art. The imspacg of this is to enable longer linear runs and/or reduced thickness of conductive stripes of indium-tin-oxide (or the like) .

The realization of reduced electrical resistivity/higher electrical conductivity is achieved with only a modest loss of optical transmissivity typically less than twenty percent at most spectral ranges of interest in electro-optic display or filter application, such as those cited above.

Realization of such improvement is preferrably made through the following process steps:

(1.1) Establish a base layer free of external ions (i.e. alkali ions as applied to a glass substrate), preferrable by beginning with a glass such as sode lime or Corning 7059. Clear the substrate with detergent and/or solvents and dry it at 150° in air or inert gas far about half an hour to remove moisture and follow up by sputter-etch or like radiant energy etch to remove residual contaminants. The sputter etching is at one-half to one kilowatt under about 8 millitorr vacuum and after prior evacuation and argon backfill.

(1.2) Cover its surface to be coated with a

(sputter-deposited or chemical-vapor-deposition deposit) silicon dioxide layer of about 2,000 Angstroms thickness to mask the alkali ions or other external species from interacting with subsequent coating and provide substrate for further coating. A pre-processed silicon glass substrate free of such surface species is another approach to the same end.

(1.3) Then the so-coated glass is heated at 350-450°C for about fifteen minutes under 5 × 10^-7 mm Hg. pressure.

(2) A layer of 7000-10,000 Angstroms of indium-tin-oxide is sputter deposited on the so-treated substrate.

(2.1) The first 100 to 200 Angstroms of such deposition (equivalent to the first few monolayers thereof) is conducted under bias sputtering conditins to maximize purity and density. The sputtering of the indium-tin-oxide is conducted in atmosphere initially evacuated to 5-10^-7 mm. Hg., then back-filled with argon of 8×10^-3 with a partial pressure of oxygen of 4 to 5×10^-5 mm. Hg.

(2.2) Without removal from the sputter system, the sputtering discharge is then terminated and a vacuum bake of 400- 500°C for about 15 minutes at 4 to 5×10^-7 mm. Hg. is applied to create oxygen vacancies.

FIG. 11 shows the development of enhanced (reduced) sheet resistivity of two samples of (1.1) soda lime and (1.2) Corning 7059 coated with indium-tin-oxide as described above. The y-axis (logarithmic) is ohms per square and the x-axis (linear) is time in minutes of the final baking step of (2.2) to create oxygen vacancies. The sheet resistivity of the samples begins at sixteen dims per square and drops dramatically to well under one ohm per square as the bate continues to over an hour, with no further change after about an hour and a half. Bulk resistivity of the coating is also reduced ╌ to about 0.5×10^-4 ohm-cm, a substantial improvement over commonly available indium-tin-oxide materials.

The processing as described above can be implemented over a broad area or through masking to provide multiple stripes of conductive coating (alternatively interval stripes can be etched or machined cut of a broad area coating).

Some of the processing steps described above can be supplemented or supplanted by laser or electron beam etching, micromachining, ion deposition, electroplating, electrophoresis and other processes.

The enhanced metallic coating can be under 20,000 Angstroms but is preferably well under 10,000. Where a glass substrate displays e.g. 92% optical transmission in visible range the metallic coated glass (with low sheet resistivity of the coating) will display over 80%, preferrably 85% or more transmissivity in the same spectral range, i.e. reduction of less than 20%, preferrably less than 10% via the coating. In contrast without the special enhancement a 10,000 Angstrom conventional coating of indium-tin-oxide on such glass would typically reduce to about 60% transmission and would have higher electrical sheet resistivity.

The above described enhancement processing modifies semicαnductive characteristics of the indium-tin-oxide coating or the like through oxygen vacancy creation (or equivalent means) to yield the lowered resistivity with a higher degree of preservation of optical transmissivity.

Filter applications of the invention - in reflective and transmissive modes - are characterized by abrasion, thermal and environment resistance, including super-saturated salt solutions anchor -55° C to +550° C range consistent with 90% transmission/reflection, ease and low cost of tailoring to particular applications.

It will new be apparent to those skilled in the art that other embodiments, improvements, details, and uses can be made consistent with the letter and spirit of the foregoing disclosure and within the scope of this patent, which is limited only by the following claims, construed in accordance with the patent law, including the doctrine of equivalents.

What is claimed is:

Claims

1. Display system comprising, in combination:

(a) light source means comprising a first slab like element comprising elongated parallel conductors therein to define a set of first electrodes and comprising a material with light control properties varied by external control,

(b) color filter means in the farm of a second slab-like element in close spacing and face-to-face opposition to said first element and comprising a series of transparent, color sensitive stripes of elongated conductors with a dielectric top layer to define second electrodes in a cross-hatch array with said first electrodes, the said dielectric layer being thereby sandwiched between said first and second electrode elements in a precisely defined arrangement,

(c) control means for activating selected ones of said first and second electrodes to effect light response at selected cross-overs thereof and light transmission essentially through the second electrodes.

2. Display system in accordance with claim 1 wherein the second electrodes comprise a transparent elongated conductor, overlaid with a valve metal which is in turn overlaid with an anodic oxide of the valve metal highly adherent to the latter and anodically formed to a selected color control thickness.

3. Display system in accordance with claim 2 wherein the valve metal comprises tantalum and the transparent conductor comprises indium/tin oxide.

4. Display system in accordance with claim 1 wherein the color sensitive stripes include repeating sets of stripes with different members of a set sensitive to different colors.

5. Display system in accordance with claim 1 wherein the color sensitive, second electrode stripes are made in less than .001 inch widths with intervals therebetween of less than .001 inch and utilizable with first electrode width of the same order of magnitude to define high resolution color dots of high intensity.

6. Display system comprising in combination:

(a) light source means, and

(b) color filter means for interacting with light from the source to emit, as a display output, a limited spectral range of the source light at a high intensity, in excess of eighty percent of the source intensity of such spectral component, and comprising a valve metal oxide on a substrate of the valve metal per se.

7. Display system in accordance with claim 6 wherein said valve metal oxide comprises tantalum pentoxide.

8. Display system in accordance with claim 6 wherein said color filter means comprises multiple areas of such valve metal oxide of differing thicknesses to effect differing spectral range responses, all at high intensity.

9. Display system in accordance with claim 8 wherein repeatling like sets of such multiple areas are provided in array form to form a display array.

10. Display system in accordance with claim 9 wherein each, set comprises side-by-side stripes of differing thickness of and the sets are in a planar array of side by side stripes.

11. Display system in accordance with claim 8 wherein interval areas are provided between areas of valve metal oxide.

12. Display system in accordance with claim 11 wherein the interval areas are opaque.

13. Display system in accordance with claim 6 wherein the color filter means interact with the light from the source by selective spectral range transmission thereof.

14. Display system in accordance with claim 6 wherein the color filter means interact with the light from the source by selective spectral range reflection thereof.

15. Display system in accordance with claim 6 wherein said light source means and color filter means are interrelated as follows:

(a) said light source being of an essentially slab form and comprising electrically responsive material and a series of spaced conductors therein to act as first electrodes and means for selectively activating said first electrode,

(b) said light filter being also of essentially slab form and having therein an array of second electrodes therein and means for selectively activating said second electrodes,

(c) the slabs being in face-to-face opposition and essentially adjacenct to each other,

(d) whereby selective activation of certain members of the first and second electrodes activates areas of the electrically responsive material at cross-over regions of the activated electrodes to effect selected areas of light control, positively or negatively (by light transmission/origination or light blockage/non-origination),

(e) the closest opposing active electrodes from the first and second sets being separated electrically by the said valve metal oxide and having a dielectric constant therein in excess of fifteen.

16. Display system in accordance with claim 15 wherein said color filter comprises a planar array of valve metal oxide coating areas an metal bases, with sufficient conductivity to serve as one of said second electrodes to interact with a corresponding first electrode of the light source.

17. Display system in accordance with claim 1 wherein said valve metal oxide stripes comprise a combination of (i) an underlying valve metal thin enough to be transparent to thespectral range of light for which the oxide thickness is graded and (ii) an optically transparent underlayer providing sufficient electrical conductivity to serve as the electrode.

18. Display system in accordance with claim 15 wherein said conductive areas of the second electrodes are elongated.

19. Display system in accordance with claim 15 wherein the light source comprises a light pasage/blockage matrix.

20. Display system in accordance with claim 15 wherein the light cource comprises a light originating matrix.

21. Display system in accordance with claim 15 wherein the two first and second electrode spacing at cross-overs is in the .001 to 0.1 inch range thereby avoiding parallax and interference effects.

22. High resolution, multi-color, thin film display system with uniform, high intensity comprising:

(a) means forming an essentially two dimensional film array of alternating assigned-color segments of high resolution, i.e., less than 0.05 inches wide, sensitive to incident light to transmit the assigned color(s) portion(s) of incident light at high intensity, with high transient speeds of activation and deactivation, and

(b) means for effecting high speed light activation and deactivation of selected segments and groups and portions thereof in the said array, the materials of the system having high chemical inertness and thermal stability under all conditions of manufacture and use and the structure of the system affording a compact display essentially free of parallax and providing an essentially isotropic light output.

23 Display system in accordance with claim 21 wherein said activation/deactivation means comprise an electrically operated matrix filter of back light.

24. Display system in accordance with claim 21 wherein said activation/deactivation means comprise an electrically operated electroluminescent matrix comprising a photovoltaic layer sandwiched between orthogonally arrayed thin electrode strips.

25. Display system in accordance with claim 21 and further comprising an integral to the film array forward protective cover which is transparent.

26. Display system in accordance with claim 24 wherein said cover comprises a glass substrate supporting said film array as a thin film coating therein.

27. Display system in accordance with claim 21 wherein said film array is a graded layer of a combination of (a) an optically-functional thickness anodic oxide of a valve metal and (b) the valve metal per se.

28. Display system in accordance with claim 21 wherein the high resolution segment patterns of components (a) and (b) are of the same order of magnitude and in respective array registration with each other.

29. laminate structure for use in color display systems comprising, in parallel layers, the following:

(a) means defining a graded thin film, and

(b) means defining an opposing generator of high resolution spots of light control of under .001 in. span resolution.

30. The laminate structure of claim 28 wherein said graded thin film means (a) comprises a repeating array of sets of graded thin film segments in each set with differential responses to incident spots of light applied thereto by said light generator means (b) .

31. The laminate structure of claim 28 wherein said graded thin film segments comprise valve metal oxide layers of graded thickness responsive to different wavelengths of incident light in the visible spectral range.

32. The laminate structure of claim 28 wherein said valve metal oxide is tantalum pentoxide.

33 The laminate structure of claim 28 wherein said generator means is a matrix filter of light.

34. The laminate structure of claim 28 wherein said generator means is a matrix source of light.

35. The laminate structure of claim 28 wherein said film is mounted on a transparent substrate.

36. Method of making color display systems comprising the step of depositing a valve metal thin film and oxidizing adjacent segments thereof to graded oxide thicknesses for differential spectral response to light, whereby multiple spectral response capability is farmed in essentially a single plane to enable simplicity of manufacture, intensity of light passage and flexibility of control.

37. Method in accordance with claim 35 wherein the valve metal is tantalum.

38. Method in accordance with claim 36 wherein the valve metal is deposited in a transparent thickness over a transparent and thicker thin film layer of a conductive material to provide an internal electrode system enabling anodic oxidation of the valve metal.

39. Method in accordance with claim 36 wherein the metals are deposited on a protective transparent substrate.

40. Method in accordance with claim 35 and further comprising the step of overlaying graded oxide segments with a high resolution flat pack matrix generator producing selected spots of light control.

41. Method of enhancing (lowering) sheet electrical resistivity of an optically transmissive metallic material comprising the creation of a modified semiconductor characteristic thereof, where the material is a coating of under 20,000 Angstroms thickness on a substrate and has an intrinsic optical transmissivity which is reduced by less than 20% by creation of the semiconductor characteristic.

42. The method of claim 40 wherein the transmissivity reduction is less than 10% and the coating thickness is less than 10,000 Angstroms.

43. The method of claim 40 wherein the coating material is indium-tin-oxide.

44. The method of claim 40 wherein the semiconductor characteristic is induced by creating oxygen vacancies.

45. A coated product is made by any of claims 41, 42 or 43.

46. A coated product as set forth in claim 44 ith a visible light transmission of over 85% with essentially complete ultra violet light blocking throughout a substantial portion of the ultraviolet spectral range, from about 200 to about 300 nanometers wavelength.