[19]
`United States Patent
`5,402,145
`[11] Patent Number:
`[45] Date of Patent: Mar. 28, 1995
`Disanto et a1.
`
`USOOS40214SA
`
`[54]
`
`[75]
`
`[73]
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`[21]
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`[22]
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`[51]
`[52]
`
`[58]
`
`[55]
`
`ELECI‘ROPHORETIC DISPLAY PANEL
`WITH ARC DRIVEN INDIVIDUAL PIXELS
`
`Inventors: Frank J. Disanto, North Hills; Denis
`A. Krusos, Lloyd Harbor, both of
`NY.
`
`Assignee: Copytele, Inc., Huntington Station,
`NY.
`
`Appl. No.: 18,111
`
`Feb. 17, 1993
`Filed:
`Int. Cl.6 ............................................... G096 3/28
`US. Cl. .................................... 345/107; 313/484;
`359/296
`Field of Search ............... 340/787, 788, 763, 771;
`313/483, 484, 358, 585, ; 359/293, 294, 295,
`296, 297; 345/107, 48, 60, 49
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`‘
`
`340/771
`9/1975
`3,904,915
`345/105
`4,583,087 4/1986
`313/484
`4,956,577
`9/1990
`340/771
`5,077,553 12/1991
`340/787
`.
`5,223,115
`1/1993
`5,223,823
`1/1993 Disanto et a]. ...................... 340/878
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`313/484
`0023262 2/1977
`345/107
`1114828
`5/1989
`345/107
`2284127 11/1990
`345/107
`3096925 4/ 1991
`345/107
`4212990 8/1992
`2020060 11/1992 WIPO ................................. 345/107
`
`
`
`Primary Examiner—Richard Hjerpe
`Assistant Examiner—Lun—Yi Lao
`Attorney, Agent. or Finn—Arthur L. Plevy
`
`[57]
`
`ABSTRACT
`
`An electrophoretic display includes a laminated triple
`pane construction with an electrophoretic fluid-con-
`taining envelope formed between the first and second
`panes and an ionizable gas-containing envelope between
`the second and third panes. A transparent reference
`electrode coats the first pane internal to the fluid enve-
`lope. A matrix of discrete pixels are disposed upon the
`second pane within the fluid envelope. Each pixel has a
`probe extending therefrom through the second pane
`and into the gas envelope. A plurality of row electrodes
`are disposed upon the second pane in the gas envelope
`in close proximity to corresponding rows of probes. A
`plurality of column electrodes disposed upon the third
`pane within the gas envelope perpendicular to the row
`lines establishes an addressable X—Y matrix. By impress-
`ing a sufficient voltage differential at selected intersec-
`tions of the matrix, a local ionization of gas biases a
`proximate probe to the ionization potential. The probe
`potential is shared by the corresponding pixel, setting
`up an electrostatic field relative to the reference elec-
`trode for controlling the movement of pigment within
`the fluid. A capacitive effect is realized upon removal of
`ionization potential whereupon the gas deionizes leav—
`ing the pixel and probe to discharge slowly through the
`dielectric fluid.
`
`17 Claims, 3 Drawing Sheets
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`US. Patent
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`US. Patent
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`Mar. 28, 1995
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`Sheet 3 of 3
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`1
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`5,402,145
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`ELECTROPHORETIC DISPLAY PANEL WITH
`ARC DRIVEN INDIVIDUAL PIXEIS
`
`FIELD OF THE INVENTION
`
`The present invention relates to an electrophoretic
`display panel apparatus and, more particularly, to an
`electrophoretic display having independent pixel ele-
`ments driven by an are through an ionizable gas.
`BACKGROUND OF THE INVENTION
`
`Electrophoretic displays (EPIDS) are now well
`known. A variety of display types and features are
`taught in several patents issued in the names of the
`inventors herein, Frank J. DiSanto and Denis A. Krusos
`and assigned to the assignee herein, Copytele, Inc. of
`Huntington Station, NY. For example, U.S. Pat. Nos.
`4,655,897 and 4,732,830, each entitled ELECTROPHO—
`RETIC DISPLAY PANELS AND ASSOCIATED
`METHODS describe the basic operation and construc-
`tion of an electrophoretic display. U.S. Pat. No.
`4,742,345, entitled ELECTROPl-IORETIC DISPLAY
`PANELS AND METHODS THEREFOR, describes
`a display having improved alignment and contrast.
`Many other patents regarding such displays are also
`assigned to Copytele, Inc.
`The display panels shown in the above-mentioned
`patents operate upon the same basic principle, viz., if a
`suspension of electrically charged pigment particles in a
`dielectric fluid is subjected to an applied electrostatic
`field, the pigment particles will migrate through the
`fluid in response, to the electrostatic field. Given a sub-
`stantially homogeneous suspension of particles having a
`pigment color different from that of the dielectric fluid,
`if the applied electrostatic field is localized it will cause
`a visually observable localized pigment particle migra-
`tion. The localized pigment particle migration results
`either in a localized area of concentration or rarefaction
`of particles depending upon the polarity and direction
`of the electrostatic field and the charge on the pigment
`particles. The electrophoretic display apparatus taught
`in the foregoing U.S. Patents are “triode-type” displays
`having a plurality of independent, parallel, cathode row
`conductor elements or “lines" deposited in the horizon-
`tal on one surface of a glass viewing screen. A layer of
`insulating photoresist material deposited over the cath-
`ode elements and photoetched down to the cathode
`elements to yield a plurality of insulator strips posi-
`tioned at right angles to the cathode elements, forms the
`substrate for a plurality of independent, parallel column
`or grid conductor elements or “lines" running in the
`vertical direction. A glass cap member forms a fluid-
`tight seal with the viewing window along the cap’s
`peripheral edge for containing the fluid suspension and
`also; acts as a substrate for an anode plate deposited on
`the interior flat surface of the cap. When the cap is in
`place, the anode surface is in spaced parallel relation to
`both the cathode elements and the grid elements. Given
`a specific particulate suspension, the sign of the electro-
`static charge which will attract and repel the pigment
`particles will be known. The cathode element voltage,
`the anode voltage, and the grid element voltage can
`then be ascertained such that when a particular voltage
`is applied to the cathode and another voltage is applied
`to the grid, the area proximate their intersection will
`assume a net charge :sufficient to attract or repel pig-
`ment particles in suspension in the dielectric fluid. Since
`numerous cathode and grid lines are employed, there
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`are numerous discrete intersection points which can be
`controlled by varying the voltage on the cathode and
`grid elements to cause localized visible regions of pig-
`ment concentration and rarefaction. Essentially then,
`the operating voltages on both cathode and grid must be
`able to assume at least two states corresponding to a
`logical one and a logical zero. Logical one for the oath-
`ode may either correspond to attraction or repulsion of
`pigment. Typically, the cathode and grid voltages are
`selected such that only when both are a logical one at a
`particular intersection point, will a sufficient electro-
`static field be present at the intersection relative to the
`anode to cause the writing of a visual bit of information
`on the display through migration of pigment particles.
`The bit may be erased, e.g., upon a reversal of polarity
`and a logical zero-zero state occurring at the intersec-
`tion coordinated with an erase voltage gradient be-
`tween anode and cathode. In this manner, digitized data
`can be displayed on the electrophoretic display.
`Besides the triode-type display, the applicant’s herein
`have proposed a variety of EPID structures for utilizing
`the electrophoretic effect. For example, an alternative
`EPID construction is described in application Ser. No.
`07/345,825, now U.S. Pat. No. 5,053,763, entitled
`DUAL ANODE FLAT PANEL-ELECTROPHO-
`RETIC DISPLAY APPARATUS, which relates to an
`electrophoretic display in which the cathode/grid ma-
`trix as found in triode—type displays is overlayed by a
`plurality of independent, separately addressable “local”
`anode lines. The local anode lines are deposited upon
`and aligned with the grid lines and are insulated there-
`from by interstitial lines of photoresist. The local anode
`lines are in addition to the “remote” anode, which is the
`layer deposited upon the anode faceplate or cap as in
`triode displays. The dual anode structure aforesaid pro-
`vides enhanced operation by eliminating unwanted var—
`iations in display brightness between frames, increasing
`the speed of the display and decreasing the anode volt-
`age required during Write and Hold cycles, all as ex-
`plained therein.
`In general, it can be noted that a variety of EPID
`configurations have been proposed by the prior art. In
`the quest for better EPID’s, improvements in resolu-
`tion, speed of operation, simplicity of construction,
`reliability and economy continue to be sought.
`An object of the present invention is to achieve an
`improved EPID structure and function.
`SUMMARY OF THE INVENTION
`
`The problems and disadvantages associated with
`conventional electrophoretic displays are overcome by
`the present invention which includes a first receptacle
`containing electrophoretic fluid and a second receptacle
`containing an ionizable gas. The first and second recep-
`tacles share a common barrier wall and a plurality of
`conductive pathways penetrate the barrier wall. A first
`end of the conductive pathways is disposed proximate
`the fluid while a second end is in contact with the gas.
`Apparatus is provided for ionizing the gas proximate
`selected conductive pathways to bias those selected
`pathways in order to induce movement of pigment in
`the fluid proximate the first end of the selected conduc-
`tive pathways.
`BRIEF DESCRIPTION OF THE FIGURES
`
`For a better understanding of the present invention,
`reference is made to the following detailed description
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`5,402,145
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`3
`of an exemplary embodiment considered in conjunction
`with the accompanying drawings, in which:
`FIG. 1 is a perspective view of an electrophoretic
`display in accordance with an exemplary embodiment
`of the present invention.
`FIG. 2 is an enlarged cross-sectional view of the
`EPID shown in FIG. 1 taken along section line 11—11
`and looking in the direction of the arrows.
`FIG. 3 is a rear elevational view of the intermediate
`pixel carrier plate of the EPID shown in FIGS. 1 and 2.
`FIG. 4 is a front elevational view of the column con-
`ductor carrier plate of the EPID shown in FIGS. 1 and
`2.
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`ment of the EPID shown in FIG. 2 illustrating opera-
`tion.
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`DETAILED DESCRIPTION OF THE FIGURES
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`FIG. 1 shows an electrophoretic display or EPID 10
`having a front faceplate 12, an intermediate pixel carrier
`plate 14 and a backplate 16. Typically, the plates 12, 14
`and 16 would be formed from glass due to its transpar-
`ency, dielectric strength and compatibility with photo-
`etching processes. The plates are separated by spacers
`18 which join the respective plates about their periph-
`ery forming a pair separate internal envelopes or recep-
`tacles, a first for containing electrophoretic fluid and a
`second for containing an ionizable gas, as shall be seen
`and described more fully below. The spacers are typi—
`cally mylar and are bonded to the respective plates
`making up the EPID 10 by epoxy which flows under
`the influence of pressure and heat and upon cooling
`bonds to form an airtight and fluid tight seal. The face-
`plate of the EPID 10 has a substantially clear indium-
`tin-oxide (ITO) electrode 20 deposited on the interior
`surface thereof through which the electrophoretic ef-
`fect may be visualized, A plurality of individual pixels
`22 disposed on the intermediate pixel carrier plate 14 are
`depicted in dashed lines. Like the faceplate electrode
`20, the individual pixels 22 may be formed of indium-
`tin-oxide (ITO) and are electrically conductive. In the
`alternative, metals such as chrome could be employed.
`Methods for depositing and shaping indium-tin—oxide on
`glass substrates are known in the art and are described,
`e.g., in the above-referenced US. Pat. Nos. 4,655,897
`and 4,732,830.
`FIG. 2 illustrates the interior components of the
`EPID 10. An anterior sealed chamber 24 receives elec—
`trophoretic fluid which includes a dielectric fluid and
`suspended therein a dispersion of colloidal surface-
`charged pigment particles, as is known in the art. Exam-
`ples of typical electrophoretic fluids are referred to in
`US. Pat. Nos. 4,655,897 and 4,732,830. One such typical
`fluid employs a dark blue or black dielectric along with
`yellow negatively surface-charged pigment particles. A
`posterior chamber 26 formed by the sealing of mylar
`seals 18 to plates 14 and 16 contains an ionizable gas
`such as Argon, Xenon or Neon or a mixture of such
`gases. The rear plate 16 supports a plurality of parallel
`column conductor lines 28 disposed in this view in the
`“vertical direction”. The conductor-lines 28 may be
`formed from ITO, chrome or any other conductor ma-
`terial in a manner which is conventional in the art, such
`as photoetching, plasma etching, etc. The individual
`pixel elements 22 disposed upon the intermediate pixel
`carrier plate 14 are electrically connected to associated
`conductor pins 30 formed from copper or any other
`suitable conductor. The conductor pins 30 penetrate the
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`intermediate pixel carrier plate 14 such that a portion
`protrudes toward the backplate 16 within the posterior
`chamber 26 and a portion protrudes toward the interior
`chamber to establish contact with an associated individ-
`ual pixel 22. If the vertical conductor members or col-
`umn lines 28 are arbitrarily described as “vertical”, the
`individual pixels may be said to be horizontally grouped
`in rows which are disposed at right angles to the verti-
`cal conductor lines 28. The grouping of the individual
`pixels 22 and associated conductor pins 30 is established
`by row conductor lines 32 which traverse the interme-
`diate pixel carrier plate 14 proximate to but not in con-
`ductive association with the conductor pins 30. Prefera-
`bly, a row conductor line 32 is disposed on either side of
`a set or row of conductor pins 30 as shall be seen more
`conveniently in FIG. 3. A pair of driver circuits 3, 35
`for driving the respective electrodes 20, 28 and 32 are
`shown diagrammatically and are such as are known in
`the art as, e.g., represented by the teachings of US. Pat.
`Nos. 4,655,897 and 4,732,830.
`FIG. 3 shows the rear portion of the intermediate
`pixel carrier plate 14 with the conductor pins 30 pene-
`trating the plate and projecting towards the viewer.
`The conductor pins 30 are organized into rows by pairs
`of row conductor lines 32 which traverse the intermedi-
`ate pixel carrier plate 14 proximate to but not touching
`the conductor pins 30. In order to provide a uniform
`electrostatic field proximate the individual conductor
`pins 30, each of a pair of the row conductor lines as-
`sumes a semicircular shape proximate thereto which
`semicircles are conjoined to encircle the pins 30 and
`coaxial spacing 33.
`FIG. 4 shows the front portion of backplate 16 upon
`which is disposed a plurality of vertical conductor lines
`28. As can be seen by referring to FIGS. 2, 3 and 4, the
`vertical conductor lines 28 align with individual pixel
`members 22 and corresponding conductor pins 30
`thereby forming a matrix with the horizontal row con-
`ductor lines 32. The conductor pins 30 are disposed at
`each intersection of the matrix. In this respect, an X, Y
`addressable matrix is formed with the individual pixels
`22 disposed at the addressable points on the matrix.
`FIG. 5 shows an enlarged fragment of the display 10
`shown in FIG. 2 with one of the conductor pins 30
`supporting an electric arc 34 traversing the gap between
`itself and an associated vertical conductor line 28. The
`electric arc is supported by the local ionization of the
`gas filling the posterior chamber 26 and originates from
`row conductor line 32. Given a voltage drop between a
`particular row conductor line 32 and an intersecting
`vertical conductor line 28 which is equal to or greater
`than the threshold voltage to create ionization across a
`particular physical gap, an electric discharge will occur
`as illustrated by electric are 34. The threshold voltage is
`dependent upon the gas and the size of the gap. Since
`the conductor pin 30 is interposed into the arc pathway
`from the row conductor lines 32 to the vertical conduc-
`tor column lines 28, the conductor pin 30 is raised to a
`voltage level corresponding to that of the electric are 34
`at the point where the arc enters the conductor pin 30.
`Given that the conductor pin 30 is in electrical continu—
`ity with a single pixel 22, the potential of pixel 22 is also
`raised or lowered to the voltage of the conductor pin. In
`this manner, the pigment particles can be controlled,
`that is by setting the voltage of the individual pixels 22
`in accordance with the voltage level of the electric are
`26. In FIG. 5, the electric are is induced by a positive
`voltage gradient from the row conductor line 32 to the
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`vertical conductor line 28 such that the conductor pin
`30 is raised to a high positive voltage thereby attracting
`the pigment particles 36 towards the individual pixel 22.
`This can be described as writing the pixel. The remain-
`der of the pigment particles 36 are retained on the face-
`plate electrode 20 by a zero or slightly positive voltage
`in areas adjacent to pixels 22 not influenced by the
`electric arc. It should be recalled that
`the anterior
`chamber 24 contains electrophoretic fluid which is a
`dielectric fluid suspending pigment particles 36 therein.
`In accordance with the operation of electrophoretic
`displays, the concentration of pigment particles proxi-
`mate to or distal to the faceplate 12 is responsible for the
`display characteristics, namely if yellow pigment parti-
`cles 36 are adhered to the faceplate electrode 20, the
`resultant image will appear yellow in all areas with
`pigment particles 36 so adhered. In areas where the
`pigment particles are removed, that is, towards the
`pixels 22, the background dielectric solution color, for
`example black, will be evidenced. Thus, a convention is
`usually established in describing the electrophoretic
`display operation wherein a written pixel is either the
`absence of pigment particles, that is, a black pixel upon
`a yellow background defined by the presence of pig-
`ment particles, or vice-versa. In the present example,
`we will use the convention that a written pixel will be
`black and that the pigment particles 36 are yellow and
`negatively charged. What has been described then is an
`apparatus for creating an electric are at a selected inter-
`section of row conductor lines 32 and vertical conduc-
`tor lines 28 to thereby influence pigment particles in an
`electrophoretic fluid which are further controlled by a
`planar faceplate electrode 20. By way of further exam-
`ple and explanation, assume that V1 volts is necessary to
`cause the gas between a conductor pin 30 and a vertical
`conductor line 28 to ionize and that V2 is equal to iv].
`If all the row conductor lines 32 are set at V1 volts, and
`all the vertical conductor members are set at V;, the gas
`will not ionize at any intersection. If the horizontal row
`conductor lines 32 are sequentially placed at V1 volts
`and the vertical conductor lines 28 are either left at V;
`or placed at 0 volts in accordance with a data pattern,
`then the gas between the electrodes which have a po-
`tential difference of V1 volts will ionize. The conductor
`pins 30 which are in contact with the ionized gas will
`therefore be at a potential approximating V1 and the
`charged pigment particles 36 will move in a direction
`consistent with the polarity of V1 since the ITO of the
`faceplate electrode 20 is maintained close to zero poten-
`tial. For example, if the row conductor lines 32 are
`sequentially placed at +100 volts and the vertical con-
`ductor lines 28 are maintained at +50 volts with a 100
`volt differential required for ionization to occur, all
`vertical conductor lines which are placed at zero volts
`will then cause an ionization at that location. It should
`be appreciated that a negative voltage of, e.g., — 100
`volts imposed on row lines 32 would reach the ioniza-
`tion threshold at intersections with column lines 28 at 0
`volts. This would result in the associated pixel at that
`intersection acquiring a potential approximating —- 100
`volts thus repelling pigment particles to the faceplate
`electrodes 20 and thereby “erasing” the pixel. After
`each row of individual pixels 22 is written or erased, the
`gas is deionized setting up a capacitive effect between
`the individual pixels 22 and the faceplate electrode 20
`since the pixels remain at the arc threshold voltage V1
`until discharged through the resistance of the electro-
`phoretic fluid. The pixels 22, as capacitors, charge
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`quickly through the low resistance of the ionized gas
`and discharge slowly through the high resistance of the
`electrophoretic fluid. If, for example, the pixels 22 are
`0.0045 inches by 0.0045 inches and the space between
`the faceplate electrode 20 and the pixel 22 is approxi-
`mately 0.0045 inches then the effective capacitance at
`each pixel is on the order of 8 microfarrads. Thus, a
`current in the micro-amp range can easily charge the
`capacitor in 50 microseconds even to a voltage of 100
`volts. The same capacitive pixel 22 will require many
`milliseconds to discharge because of the high resistance
`of the suspension. In this manner, a unique TFI‘ ar-
`rangement can be achieved and the panel can be written
`at very fast rates approaching those of video. In accor-
`dance with an alternative embodiment, holes of approx-
`imately 0.0036 inches in diameter in the intermediate
`pixel carrier plate 14 could be employed instead of the
`conductor pins 30 which traverse the plate from the
`pixel to the gas envelope in the posterior chamber 26.
`The holes would form a matrix of individual gas dis-
`charge lamps. This configuration can readily be envi-
`sioned by simply removing the probes 30 shown in FIG.
`5.
`
`It should be understood that the embodiments de-
`scribed herein are merely exemplary and that a person
`skilled in the art may make many variations and modifi-
`cations without departing from the spirit and scope of
`the invention as defined in the appended claims.
`What is claimed is:
`
`1. An electrophoretic display, comprising:
`a dielectric barrier wall having a first surface and an
`opposite second surface;
`a transparent faceplate disposed proximate said first
`surface of said barrier wall wherein said transpar-
`ent faceplate and said first surface of said barrier
`wall define at least part of a fluid impermeable
`receptacle:
`a backplate disposed proximate said second surface of
`said barrier wall, wherein said backplate and said
`second surface of said barrier wall define at least
`part of a gas impermeable receptacle;
`an electrophoretic dispersion containing electropho-
`retic particles suspended in a suspension fluid,
`wherein said dispersion is contained within said
`fluid impermeable receptacle;
`an ionizable gas contained within said gas imperme—
`able receptacle;
`a plurality of conductive elements extending through
`said barrier wall from said first surface to said sec-
`ond surface, wherein each of said conductive ele-
`ments are insulated from each other and each of
`said conductive elements communicates with said
`electrophoretic dispersion and said ionizable gas;
`a first plurality of conductive pathways disposed on
`said second surface of said barrier wall;
`a second plurality of conductive pathways disposed
`on said backplate; and
`means for producing an are through said ionizable
`gas, promote a selected one of said conductive
`elements, between one of said first plurality of
`conductive pathways and one of said second plu-
`rality of conductive pathways, wherein said are
`applies an electrical bias to one of said conductive
`elements that traverses the barrier wall and creates
`an electrophoretic effect within said electropho-
`retic dispersion.
`2. The device of claim 1, wherein said first plurality
`of conductive pathways includes a plurality of substan-
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`7
`tially parallel column conductor lines disposed on sec—
`ond surface of said barrier wall and said second plural-
`ity of conductive pathways include a plurality of row
`conductor lines disposed on said backplate in an orienta-
`tion that is substantially perpendicular to said column
`conductor lines, thereby forming an addressable X-Y
`matrix.
`3. The device of claim 2, further including a reference
`electrode disposed fin said faceplate, wherein said refer-
`ence electrode is in contact with said electrophoretic
`dispersion and generally faces said first surface of said
`barrier wall.
`4. The device of claim 3, further including means for
`applying a predetermined electrical bias to said refer-
`ence electrode.
`5. The device of claim 1, further including a plurality
`of discrete conductive pixels disposed upon said first
`surface of said barrier wall, wherein each of plurality of
`pixels is paired in electrically conductive association
`with a corresponding one of said plurality of conductive
`elements.
`6. The device of claim 2, wherein each of said plural-
`ity of conductive elements is disposed on said second
`surface of said barrier wall at a position proximate a
`corresponding intersection of said XvY matrix.
`7. The device of claim 6, wherein said selected con-
`ductive pathways are biased through contact with an
`ionized portion of said gas.
`8. The device of claim 1 wherein said faceplate is
`bonded to said barrier wall with a first insulating spacer
`that separates said faceplate from said barrier wall and
`defines said fluid impermeable receptacle.
`9. The device of claim 8, wherein said backplate is
`bonded to said barrier wall with a second spacer that
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`separates said backplate from said wall and defines said
`gas impermeable receptacle.
`10. The device of claim 9, wherein said reference
`electrode is disposed upon said faceplate, plurality of
`column lines are disposed on said backplate and plural—
`ity of row lines are disposed upon said barrier wall.
`11. The device of claim 1, wherein said faceplate, said
`backplate and said barrier wall are each substantially
`parallel, coextensive, plate-like members.
`12. The device of claim 1, wherein, said backplate and
`said barrier wall are each substantially transparent.
`13. The device of claim 1, wherein each of said plural-
`ity of conductive pathways is an elongated conductor
`member.
`14. The device of claim 2, wherein said plurality of
`row conductor lines are grouped in pairs maintained at
`equivalent electrical potential relative each other and
`said conductive elements arranged in a plurality of
`rows, each between a corresponding pair of row con-
`ductor lines.
`15. The device of claim 5, wherein said pixels, said
`first plurality of conductive pathways and said second
`plurality of conductive pathways are formed from in-
`dium tin oxide and are substantially transparent.
`16. The device of claim 7, wherein said selected con-
`ductive pathways are biased by said ionized portion to a
`potential proportional to the dielectric strength of said
`gas.
`17. The device of claim 12, wherein each of said
`plurality of conductive pathways is an aperture within
`said barrier wall communicating with said second re-
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