Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
  • G09G3/3433—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices
  • G09G3/344—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on particles moving in a fluid or in a gas, e.g. electrophoretic devices
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1345—Conductors connecting electrodes to cell terminals
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/166—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect
  • G02F1/167—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect by electrophoresis
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/1675—Constructional details
  • G02F1/1676—Electrodes
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/1675—Constructional details
  • G02F1/1676—Electrodes
  • G02F1/16766—Electrodes for active matrices
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1345—Conductors connecting electrodes to cell terminals
  • G02F1/13456—Cell terminals located on one side of the display only
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/04—Structural and physical details of display devices
  • G09G2300/0421—Structural details of the set of electrodes
  • G09G2300/0426—Layout of electrodes and connections
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/0219—Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling

Definitions

• this invention relates to slim border display panels for tiled electro-optic displays, e.g., electrophoretic displays. It would be beneficial to develop systems and methods having reduced capacitive coupling to pixel electrodes in the display panel.
• an electro-optic display including a driver chip and a backplane.
• the backplane includes a substrate that has a front side with pixel electrodes arranged in an array including pixel rows and pixel columns.
• Each of the pixel rows includes a row line (i.e., source line) running parallel to the pixel row, wherein each row line is coupled to a T-wire.
• the T-wire is also being coupled to the driver chip, and the T-wire runs along a back side of the substrate in a direction substantially perpendicular to the row line.
• Each T-wire transitions from the back side of the substrate to the front side of the substrate through a via.
• Each via for each T- wire has a nearest neighbor via, and the via and the nearest neighbor via are separated by at least one pixel column.
• the nearest neighbor of a via can be identified by drawing consecutive circles with increasing radii, but having a center at the via. The first time a second via is captured by one of the concentric circles, it is a nearest neighbor via. There may be two or more equivalent nearest neighbors based upon radial distance.
• the invention provides for an electro-optic display including a driver chip and a backplane.
• the backplane includes a substrate, the substrate including a viewing surface having a plurality of pixel electrodes arranged in an array of a plurality of pixel rows and a plurality of pixel columns, each of the plurality of pixel rows having a row line associated therewith.
• a first pixel column of the plurality of pixel columns has a first plurality of T- wires associated therewith, each of the first plurality of T- wires being connected to the driver chip.
• Each of the first plurality of T- wires is connected to a respective one of a first plurality of row lines by one of a first plurality of vias disposed within the backplane, the first plurality of vias being arranged within the backplane such that vias associated with two adjacent pixel rows are not associated with a same pixel column.
• the invention provides for an electro-optic display including a driver chip and a backplane.
• the backplane includes a substrate, the substrate including a viewing surface having a plurality of pixel electrodes arranged in an array of a plurality of pixel rows and a plurality of pixel columns.
• Each of the plurality of pixel rows has a row line associated therewith, a first pixel column of the plurality of pixel columns having a first plurality of T- wires associated therewith.
• Each of the first plurality of T-wires is connected to the driver chip, and each of the first plurality of T-wires being connected to a respective one of a first plurality of row lines by one of a first plurality of vias disposed within the backplane.
• the first plurality of vias are arranged within the backplane such mat no two vias are associated with adjacent pixel rows of any pixel column.
• the invention additionally includes a large format display including a plurality of electro-optic displays, including a driver chip and a backplane, as described herein. Because of the T-wire arrangement, individual electro-optic displays can be butted together with very little non-active area between the panels. Because the vias are staggered, or arranged in a pseudo-random pattern, the capacitive coupling between the pixel electrodes and the T-wire is greatly reduced, thereby resulting in higher quality images (i.e., better contrast between color states and less remnant image after an image is switched, a.k.a. "ghosting").
• the invention provides for a method of forming an electro-optic display.
• the method includes providing a driver chip and a backplane, the backplane including a substrate having a plurality of pixel electrodes arranged in an array of a plurality of pixel rows and a plurality of pixel columns, where each of the plurality of pixel rows having a row line associated therewith.
• the method also includes forming a first plurality of T-wires associated with a first pixel column of the plurality of pixel columns, where each of the first plurality of T-wires being connected to the driver chip.
• the method further includes forming a first plurality of vias within the backplane such that no two vias are associated with adjacent pixel rows of any pixel column.
• the method still further includes connecting each of the first plurality of T- wires to a respective one of a first plurality of row lines using one of the first plurality of vias disposed within the backplane.
• the invention provides for an electro-optic display including a driver chip and a backplane.
• the backplane includes a substrate, the substrate including a viewing surface having a plurality of pixel electrodes arranged in an array of a plurality of pixel rows and a plurality of pixel columns. Each of the plurality of pixel rows has a row line associated therewith. A pixel column of the plurality of pixel columns has a plurality of T-wires associated therewith. Each of the plurality of T-wires being connected to the driver chip.
• Each of the plurality of T- wires is connected to a respective one of a plurality of row lines by one of a plurality of vias disposed within the backplane, where the plurality of vias is arranged within the backplane in a zigzag pattern.
• FIG. 1 A shows source signal routing in a conventional display panel
• FIG. 1 B shows source signal routing in a slim border display panel including T-wires connecting each source line to the controller
• FIG. 2 shows an equivalent circuit model of a pixel wherein T-wires running adjacent a pixel electrode couple capacitively with the pixel electrode;
• FIG. 3 A shows conventional placement of vias on a backplane relative to the pixel array wherein the T-wires for several adjacent rows of pixels are associated with the same column of pixels;
• FIG. 3B shows an embodiment of the invention (i.e. a zigzag design) in which the T-wires associated with adjacent pixel rows are each associated with a different pixel column in a diagonal pattern moving from side to size across the width of the display panel;
• FIG. 4 is a flow chart of a process for forming an electro-optic display using the methods of the invention
• FIG. S depicts a tiled display comprising three backplanes of the invention.
• electro-optic display technology is expanding beyond "typical" display applications like TV screens and monitors to include display products such as electronic books, product labels, retail shelf labels, device monitoring indicators, wristwatches, signs, and promotional or advertising displays.
• electro-optic displays are encased by a frame or a bezel to hide the electrical connections of the display which generally lay along the perimeter of the display.
• T-wire thin film transistors
• TFTs thin film transistors
• the substrate is typically made from a nonconductive material
• a capacitance is created between a pixel electrode and the multiple T- wires.
• the T-wires are typically arranged in an orderly fashion, it is often the case the multiple T-wires in close proximity are energized at the same time because they are being used to drive transitions of nearby pixel neighbors in the pixel array. This capacitive coupling can lead to unwanted optical defects.
• the invention overcomes this capacitive coupling by distributing the T- wires to spread out the capacitive coupling over the entire pixel array.
• the invention includes an electro-optic display having an array of pixel electrodes, where each row of pixel electrodes is associated with a source line, and that source line is connected to a drive chip with a T-wire that connects from the back of the substrate to the front of the substrate through a via.
• the vias are spaced out, such as in a zig-zag pattern or a pseudo-random pattern to reduce the capacitive coupling between the T-wires when adjacent pixels are driven, for example when presenting text characters.
• backplane is used herein consistent with its conventional meaning in the art of electro-optic displays and in the aforementioned patents and published applications, to mean a rigid or flexible material provided with one or more electrodes.
• the backplane may also be provided with electronics for addressing the display, or such electronics may be provided in a unit separate from the backplane.
• a backplane may contain multiple layers.
• a backplane may be referred to as a rear electrode structure.
• the front surface of a backplane refers to the surface closest to the front electrode of the display.
• the reverse surface of a backplane refers to the surface farthest from the front electrode.
• viewing surface is used herein consistent with its conventional meaning in the art of electro-optic displays and in the aforementioned patents and published applications, to mean the surface closest to the front electrode (the surface remote from the backplane).
• non-viewing surface is used herein to mean any surface or side that is not the viewing surface. This includes the reverse side of a backplane, the sides of a backplane and, if multi-layered, any layer of the backplane that is not on the viewing surface.
• a backplane has an array of pixel electrodes.
• Each pixel electrode forms part of a "pixel unit” which usually also includes a thin-film transistor, a storage capacitor, and conductors that electrically connect each pixel unit to a driver chip.
• pixel is technically a subpart of a pixel unit, the terms “pixel” and “pixel electrode” are commonly used interchangeably and refer to a unit cell of a backplane active area.
• the terms “column lines” and “row lines” generally refer to the “gate lines” and “source lines,” respectively, of a pixel transistor. These terms are used interchangeably herein.
• Arrays of transistors can be manufactured using any one of many appropriate methods.
• vacuum based methods such as evaporation or sputtering can be used to deposit the materials necessary to form the transistor and thereafter the deposited material can be patterned.
• wet printing methods or transfer methods can be used to deposit the materials necessary to form the transistors.
• the substrate may be, for example: a silicon wafer, a glass plate; a steel foil; or a plastic sheet.
• the gate electrodes for example, may be any conductive material such as metal or conductive polymer.
• the materials for use as the semiconductor layer for example, can be inorganic materials such as amorphous silicon or polysilicon.
• the semiconductor layer may be formed of organic semiconductors such as:
• any semi conductive material useful in creating conventional thin film transistors can be used in this embodiment.
• the material for the gate dielectric layer may be an organic or an inorganic material. Examples of suitable materials include, but are not limited to, polyimides, silicon dioxide, and a variety of inorganic coatings and glasses.
• the source and gate electrodes may be made of any conductive material such as metal or conductive polymer.
• the array of transistors may be any type of transistors used for addressing an electronic display. Additional (i.e., resistors) or alternative (i.e., capacitors and transistors) drive components may be used as well.
• the addressing electronic backplane could incorporate diodes as the nonlinear element, rather than transistors.
• the present invention is applicable to a variety of electronic displays, including electrophoretic displays, liquid crystal displays, emissive displays (including organic light emitting materials) and rotating ball displays.
• electro-optic as applied to a material or a display, is used herein in its conventional meaning in the imaging art to refer to a material having first and second display states differing in at least one optical property, the material being changed from its first to its second display state by application of an electric field to the material.
• the optical property is typically color perceptible to the human eye, it may be another optical property, such as optical transmission, reflectance, luminescence or, in the case of displays intended for machine reading, pseudo-color in the sense of a change in reflectance of electromagnetic wavelengths outside the visible range.
• An electro-optic display may include a liquid crystal display (LCD), a light-emitting diode (LED) or organic light emitting diode (OLED) display, or an electrophoretic display (EPD or EPID).
• solid electro-optic displays include rotating bichromal member displays, encapsulated electrophoretic displays, microcell electrophoretic displays and encapsulated liquid crystal displays.
• electro-optic displays are known.
• One type of electro- optic display is a rotating bichromal member type as described, for example, in U.S. Patents Nos. 5,808,783; 5,777,782; 5,760,761; 6,054,071 6,055,091; 6,097,531;
• Such a display uses a large number of small bodies (typically spherical or cylindrical) which have two or more sections with differing optical characteristics, and an internal dipole. These bodies are suspended within liquid-filled vacuoles within a matrix, the vacuoles being filled with liquid so that the bodies are free to rotate. The appearance of the display is changed by applying an electric field thereto, thus rotating the bodies to various positions and varying which of the sections of the bodies is seen through a viewing surface.
• This type of electro- optic medium is typically bistable.
• an electrochromic medium for example an electrochromic medium in the form of a nanochromic film comprising an electrode formed at least in part from a semi-conducting metal oxide and a plurality of dye molecules capable of reversible color change attached to the electrode; see, for example O'Regan, B., et al., Nature 1991, 353, Til; and Wood, D., Information Display, 18(3), 24 (March 2002). See also Bach, U., et al., Adv. Mater., 2002, 14(11), 845. Nanochromic films of this type are also described, for example, in U.S. Patents Nos. 6,301,038; 6,870,657; and 6,950,220. This type of medium is also typically bistable.
• Electrophoretic displays can have attributes of good brightness and contrast, wide viewing angles, state bistability, and low power consumption when compared with liquid crystal displays. Nevertheless, problems with the long-term image quality of these displays have prevented their widespread usage. For example, particles that make up electrophoretic displays tend to settle, resulting in inadequate service-life for these displays.
• electrophoretic media require the presence of a fluid.
• this fluid is a liquid, but electrophoretic media can be produced using gaseous fluids; see, for example, Kitamura, T., et al.,
• micro cell electrophoretic display A related type of electrophoretic display is a so-called "micro cell electrophoretic display".
• the charged particles and the fluid are not encapsulated within microcapsules but instead are retained within a plurality of cavities formed within a carrier medium, typically a polymeric film. See, for example, U.S. Pat. Nos. 6,672,921 and 6,788,449, both assigned to SiPix Imaging, Inc.
• electrophoretic media are often opaque (since, for example, in many electrophoretic media, the particles substantially block transmission of visible light through the display) and operate in a reflective mode
• many electrophoretic displays can be made to operate in a so-called "shutter mode" in which one display state is substantially opaque and one is light-transmissive. See, for example, U.S. Pat. Nos. 5,872,552; 6,130,774; 6,144,361; 6,172,798; 6,271,823; 6,225,971; and
• the word “printing” is intended to include all forms of printing and coating, including, but without limitation: pre-metered coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating; roll coating such as knife over roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; silk screen printing processes; electrostatic printing processes; thermal printing processes; ink-jet printing processes; electrophoretic deposition (See U.S. Pat. No. 7,339,715); and other similar techniques.)
• pre-metered coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating
• roll coating such as knife over roll coating, forward and reverse roll coating
• gravure coating dip coating
• spray coating meniscus coating
• spin coating spin coating
• brush coating air knife coating
• silk screen printing processes electrostatic printing processes
• thermal printing processes ink-jet printing processes
• electrophoretic deposition See U.S. Pat. No. 7,339,715)
• An electrophoretic display normally comprises a layer of electrophoretic material and at least two other layers disposed on opposed sides of the electrophoretic material, one of these two layers being an electrode layer.
• both the layers are electrode layers, and one or both of the electrode layers are patterned to define the pixels of the display.
• one electrode layer may be patterned into elongate row electrodes and the other into elongate column electrodes running at right angles to the row electrodes, the pixels being defined by the intersections of the row and column electrodes.
• one electrode layer has the form of a single continuous electrode and the other electrode layer is patterned into a matrix of pixel electrodes, each of which defines one pixel of the display.
• electrophoretic display which is intended for use with a stylus, print head or similar movable electrode separate from the display, only one of the layers adjacent the electrophoretic layer comprises an electrode, the layer on the opposed side of the electrophoretic layer typically being a protective layer intended to prevent the movable electrode damaging the electrophoretic layer.
• the manufacture of a three-layer electrophoretic display normally involves at least one lamination operation.
• an encapsulated electrophoretic display in which an encapsulated electrophoretic medium comprising capsules in a binder is coated on to a flexible substrate comprising indium-tin-oxide ( ⁇ ) or a similar conductive coating (which acts as one electrode of the final display) on a plastic film, the capsules/binder coating being dried to form a coherent layer of the electrophoretic medium firmly adhered to the substrate.
• a backplane containing an array of pixel electrodes and an appropriate arrangement of conductors to connect the pixel electrodes to drive circuitry, is prepared.
• the substrate having the
• capsule/binder layer thereon is laminated to the backplane using a lamination adhesive.
• a lamination adhesive A very similar process can be used to prepare an electrophoretic display usable with a stylus or similar movable electrode by replacing the backplane with a simple protective layer, such as a plastic film, over which the stylus or other movable electrode can slide.
• the backplane is itself flexible and is prepared by printing the pixel electrodes and conductors on a plastic film or other flexible substrate.
• the preferred lamination technique for mass production of displays by this process is roll lamination using a lamination adhesive. Similar manufacturing techniques can be used with other types of electro-optic displays.
• a microcell electrophoretic medium or a rotating bichromal member medium may be laminated to a backplane in substantially the same manner as an encapsulated electrophoretic medium.
• electrophoretic displays As discussed in the aforementioned U.S. Pat. No. 6,982,178, (see column 3, line 63 to column S, line 46) many of the components used in electrophoretic displays, and the methods used to manufacture such displays, are derived from technology used in liquid crystal displays (LCD's).
• LCD's liquid crystal displays
• electrophoretic displays may make use of a backplane comprising an array of transistors or diodes and a corresponding array of pixel electrodes, and a "continuous" front electrode (in the sense of an electrode which extends over multiple pixels and typically the whole display) on a transparent substrate, these components being essentially the same as in LCD's.
• the methods used for assembling LCD's cannot be used with encapsulated electrophoretic displays.
• LCD's are normally assembled by forming the backplane and front electrode on separate glass substrates, then adhesively securing these components together leaving a small aperture between them, placing the resultant assembly under vacuum, and immersing the assembly in a bath of the liquid crystal, so that the liquid crystal flows through the aperture between the backplane and the front electrode. Finally, with the liquid crystal in place, the aperture is sealed to provide the final display.
• Electro-optic displays can be costly; for example, the cost of the color LCD found in a portable computer is typically a substantial fraction of the entire cost of the computer.
• PDA's personal digital assistants
• a display is reflective or transmissive, and whether or not the electro-optic medium used is bistable, to obtain a high-resolution display, individual pixels of a display must be addressable without interference from adjacent pixels.
• One way to achieve this objective is to provide an array of non-linear elements, such as transistors or diodes, with at least one non-linear element associated with each pixel, to produce an "active-matrix" display.
• An addressing or pixel electrode, which addresses one pixel, is connected to an appropriate voltage source through the associated non-linear element.
• the pixel electrode is connected to the drain of the transistor, and this arrangement will be assumed in the following description, although it is essentially arbitrary and the pixel electrode could be connected to the source of the transistor.
• the pixels are arranged in a two-dimensional array of rows and columns, such that any specific pixel is uniquely defined by the intersection of one specified row and one specified column.
• the sources of all the transistors in each column are connected to a single column electrode, while the gates of all the transistors in each row are connected to a single row electrode; again the assignment of sources to rows and gates to columns is conventional but essentially arbitrary, and could be reversed if desired.
• the row electrodes are connected to a row driver, which essentially ensures that at any given moment only one row is selected, i.e., that there is applied to the selected row electrode a voltage such as to ensure that all the transistors in the selected row are conductive, while there is applied to all other rows a voltage such as to ensure that all the transistors in these non-selected rows remain non-conductive.
• the column electrodes are connected to column drivers, which place upon the various column electrodes voltages selected to drive the pixels in the selected row to their desired optical states.
• the aforementioned voltages are relative to a common front electrode, which is conventionally provided on the opposed side of the electro-optic medium from the non-linear array and extends across the whole display.) After a pre-selected interval known as the "line address time" the selected row is deselected, the next row is selected, and the voltages on the column drivers are changed to that the next line of the display is written. This process is repeated so that the entire display is written in a row-by-row manner.
• a transistor includes a gate electrode, an insulating dielectric layer, a semiconductor layer and source and drain electrodes.
• Application of a voltage to the gate electrode provides an electric field across the dielectric layer, which dramatically increases the source-to-drain conductivity of the semiconductor layer. This change permits electrical conduction between the source and the drain electrodes.
• the gate electrode, the source electrode, and the drain electrode are patterned.
• the semiconductor layer is also patterned in order to minimize stray conduction (i.e., cross-talk) between neighboring circuit elements.
• Electro-optic displays are often used to form large area displays, for example in the form of large signs or billboards. Such large area displays are frequently formed by "tiling" (i.e., juxtaposing) a two-dimensional array of discrete electro-optic displays together since, for technical reasons, such as limitations on the size of backplanes produced by photolithography, individual electro-optic displays cannot economically exceed a certain size. To create the illusion of a single large area display, it is important that the whole visible area of the display be active, with no inactive borders between adjacent displays. Unfortunately, conventional electro-optic displays require driver electronics which are normally disposed around the periphery of the display.
• peripheral driver electronics are not a problem when displays are used individually, since the active area of the display is normally surrounded by a bezel which serves to hide the driver electronics.
• peripheral driver electronics do create a problem when multiple displays are used to form a large area display since the peripheral areas are inherently optically inactive. Accordingly, there is a need a way of tiling electro-optic displays together to form large area displays without introducing inactive areas in peripheral portions of the individual displays.
• Slim border displays may be used in certain arrangements ("tiling") in which a number of such display panels are arranged in a group to produce a larger display. In so doing, it is preferable to reduce or eliminate the border regions on such display panels so that the pixels of adjacent display panels may be as close together as possible, which facilitates joining together multiple such display panels together to create an appearance of a single, continuous array of pixels across the grouping of display panels.
• FIG. 1 A shows a single display panel having a series of source lines having connections that run along a border of the display panel.
• a strategy for reducing or eliminating a need for a border that extends beyond the pixels themselves is to route such lines in the region of the pixel array along a back side of the display panel (i.e., the side opposite the display pixels on a front side of the panel) and through one or more vias (sometimes referred to as "via holes” or “conductive vias") toward the front side of the display panel.
• via holes sometimes referred to as "via holes” or "conductive vias”
• FIG. IB a series of T- wires run from a driver chip (labeled "IC" in FIG. IB) along the back side of the display panel and are then electrically coupled to particular source lines on the front side of the panel through individual conductive vias mat run through the display panel.
• FIG. IB it is typical that one separate T-wire and one separate via are used to establish a connection with each individual source line.
• most of the columns of pixels i.e. the lines of pixels in the long dimension, which are shown as being vertically arranged in FIG. IB
• the grouping of T-wires running in the vertical direction typically corresponds to adjacent source lines, as shown in FIG. IB.
• via apertures are made through the backplane and filled with conductive material to facilitate interconnecting electronic components on the viewing side to electronic components on the reverse side of the backplane.
• the conductive material may be electronic solder, silver, tin, aluminum, gold, lead, or another conductive metal.
• the via apertures may be, for example, etched, punched, drilled or laser-drilled through the polymeric material of the backplane so as to connect the electronic components on the viewing side to the drivers on the reverse side.
• the via apertures may be filled using a variety of materials and techniques including printing (for example, ink-jet, screen, or offset printing) application of conductive resins, shadow-mask evaporation, or conventional photolithographic methods.
• FIG. 2 shows an equivalent circuit model of a single pixel of the type mat may be used in the pixel arrays of FIGs. 1A, IB, 3 A, and 3B.
• the capacitive coupling of three underlying T-wires is depicted as C p u, Cpt2, and Cpo, however fewer or more than three wires may be included in the model as correspond to the number of wires running proximate to a pixel.
• the T-wires that are associated with the source lines needed to activate the group of dark pixels are adjacent the second and third columns of pixels.
• activating the 12-pixel block in FIG. 3A requires activation of six T-wires, three of which are adjacent to the second column of pixels and three of which are adjacent to the third column of pixels.
• each of the second and third columns of pixels is at least partially activated due to capacitive coupling that occurs between the groups of T- wires and the pixel electrodes, causing ghosting of these columns of pixels.
• the vias may be formed in the panels in a pattern that results in an arrangement of T- wires in which the T- wires that couple to the source lines of two adjacent pixel rows are associated with different pixel columns.
• one way to create this distribution of T- wires is to locate the vias in a staggered, or "zigzag,” pattern in which the vias are arranged in a diagonal pattern mat extends back and forth across the width of the panel, such that each of the plurality of T- wires are connected to row lines associated with a plurality of non-adjacent rows. As seen in the example zigzag design in FIG.
• the vias within the same column are vertically separated (e.g., by four or more intervening rows) and they are horizontally separated (e.g., by at least one column), which reduces the likelihood of two or more T-lines in the same column being simultaneously activated when a contiguous block of nearby pixels is displayed.
• vertically separated e.g., by four or more intervening rows
• horizontally separated e.g., by at least one column
• Nearest neighbor vias may be separated by, e.g., at least one pixel row, e.g., at least two pixel rows, e.g., at least three pixel rows, e.g., at least four pixel rows, and/or by at least one pixel column, e.g., at least two pixel columns, e.g., at least three pixel r columns, e.g., at least four pixel columns.
• the vias corresponding to adjacent source lines are associated with different pixel columns so that when pixels in adjacent rows are activated, each of the T-wires is associated with a different pixel column. That is, the zigzag via hole design separates the via holes in each column and hence decreases the probability of capacitive coupling from the three T-wires occurring at the same time.
• the maximum number of T-wires in each pixel column that delivers the voltage sequences for black is one. Hence, the reduced difference of luminance shift between each pixel column leads to a reduction in ghosting.
• a further advantage of the zigzag via design is that adjacent data lines have similar RC loading, which reduces or eliminates ghosting due to differences in RC delays between adjacent data lines.
• this design one can separate vias associated with adjacent rows into different pixel columns while maintaining a similar RC constant for the adjacent data lines/T-wires.
• a randomly-distributed via hole design may also be used to address T-wire induced ghosting.
• the vias may be distributed in a random or pseudorandom arrangement.
• the random or pseudorandom arrangement can be coupled with other rules such as prohibiting an arrangement of vias that leads to two or more T-wires that are associated with adjacent pixel rows being adjacent the same pixel column.
• a pseudorandom number generator for example, may be used to generate a sequence of numbers representing the order of vias.
• an advantage of a random or pseudorandom via arrangement is that it can avoid the ghosting which might occur in the zigzag design when displaying images having a periodic structure.
• FIG. 4 is a flow chart of an exemplary process 400 for forming an electro- optic display.
• the process 400 includes a step of providing a driver chip and a backplane (step 410).
• the backplane may include a substrate having a plurality of pixel electrodes arranged in an array of pixel rows and pixel columns, where each of the pixel rows has a row line associated therewith.
• the process 400 may also include a step of forming a plurality of T-wires associated with at least one of the pixel columns (step 420). Each of the plurality of T-wires may be connected to the driver chip.
• the process 400 may further include a step of forming a plurality of vias within the backplane (step 430) such that no two nearest neighbor vias are associated with adjacent pixel rows of any pixel column.
• the process 400 may also include a step of connecting each of the plurality of T-wires to a respective plurality of row lines (step 440) using one of the plurality of vias disposed within the backplane.
• Process 400 of FIG. 4 may be used to produce displays such as those disclosed herein including the display panel shown in FIG. 3B.
• multiple backplanes of the invention may be tiled together to create a large format display.
• three backplanes S 10 may be arranged on a support 520 so that they appear at a distance to be a singular large display.
• Such constructions are particularly useful for digital signage, and greatly reduce fabrication costs because they can be built in a modular fashion.

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• 2019
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