HK1258951B - Electro-optic display apparatus - Google Patents

Description

electro-optical display devices

Citation of Related Applications

This application claims priority to U.S. Provisional Application No. 62/348,801, filed on June 10, 2016. The entire contents of the above-referenced application are incorporated herein by reference.

Technical Field

The present invention relates to electro-optical display devices. More particularly, the present invention provides means for assembling a plurality of electro-optical displays into a larger display device in a convenient manner.

Background Art

For some display applications, it may be desirable to assemble multiple electro-optical displays together to form a larger display screen. In order to connect multiple displays, a set of connecting cables is typically required to connect each display to an electrical driver unit. In addition, one or more alignment frame structures are required to correctly position the displays. The overall assembly of the displays typically requires careful measurement and precise placement of the individual displays. In operation, the connecting cables are highly customized to the individual display device designs, and in addition, the customized connecting cables can be time-consuming to assemble and prone to errors during installation, making this approach only suitable for low-volume applications and prototypes. Alternatively, the display connection can include modular sub-components that can be interconnected to span the distance between each display and the driver unit. In this way, such an approach is only feasible for high-volume applications, where production costs can be amortized over the large number of display devices produced.

The subject matter presented herein provides a means to conveniently and inexpensively assemble multiple displays into display devices in various configurations.

Summary of the Invention

The subject matter presented herein provides a display device having multiple display surfaces controlled by a controller, the display device having a mounting substrate for mounting the multiple display surfaces, a mounting structure having a conductor layer for providing electrical connections to the multiple display surfaces, and at least one display surface being sufficiently flexible to have a curvature, wherein the curvature creates a space between the at least one display surface and the mounting structure to accommodate the controller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 shows an electrophoretic image display according to the subject matter presented herein;

FIG2 illustrates an exemplary mounting structure for assembling multiple displays according to the subject matter presented herein;

FIG3 illustrates a set of conductive interconnects according to the subject matter presented herein; and

FIG4 illustrates a printed graphics layer according to the subject matter presented herein;

FIG5 illustrates an exemplary pixel conductor layer of a display tile having a plurality of irregularly shaped pixel drive electrodes according to the subject matter presented herein;

FIG6 illustrates an exemplary substrate for display tiles according to the subject matter presented herein;

FIG7 illustrates a reverse conductor layer with conductive traces according to the subject matter presented herein;

8A and 8B illustrate flexible display tiles having various curvatures; and

FIG. 9 shows a flexible display tile mounted to a mounting structure.

DETAILED DESCRIPTION

The subject matter presented herein relates to an apparatus for assembling multiple electro-optical displays. Such an apparatus may include a conductive interconnect layer having a set of printed conductive interconnects for connecting the multiple displays and a printed graphic cover layer for aligning the displays. The subject electro-optical displays are particularly, but not exclusively, intended for use in particle-based electrophoretic displays, in which one or more types of charged particles are suspended in a liquid and move through the liquid under the influence of an electric field to change the appearance of the display.

The term "electro-optical," as applied to a material or display, is used herein in its conventional sense in the field of imaging, and refers to a material having first and second display states that differ in at least one optical property, the material being caused to change from its first display state to its second display state by applying an electric field to the material. While the optical property is typically color perceptible to the human eye, it may be another optical property, such as light transmission, reflection, luminescence, or, in the case of displays intended for machine reading, false color in the sense of a change in reflectivity at electromagnetic wavelengths outside the visible range.

The term "grey state" is used herein in its conventional sense in the field of imaging to refer to a state between the two extreme optical states of a pixel, but does not necessarily imply a black and white transition between the two extreme states. For example, several of the patents and published applications referred to below describe electrophoretic displays in which the extreme states are white and dark blue, so that the intermediate "grey state" is actually light blue. In fact, as already mentioned, the change in optical state may not be a color change at all. The terms "black" and "white" may be used hereinafter to refer to the two extreme optical states of a display and should be understood to generally include extreme optical states that are not strictly black and white, such as the white and dark blue states mentioned above. The term "monochrome" may be used hereinafter to refer to a drive scheme in which pixels are driven only to their two extreme optical states, without any grey states in between.

Some electro-optic materials are solid in the sense that they have a solid outer surface, although they can, and often do, have internal spaces filled with liquid or gas. Such displays using solid-state electro-optic materials may be referred to hereinafter for convenience as "solid-state electro-optic displays." Thus, the term "solid-state electro-optic display" includes rotating two-color member displays, encapsulated electrophoretic displays, microcell electrophoretic displays, and encapsulated liquid crystal displays.

The terms "bistable" and "bistability" are used herein in their conventional sense in the art to refer to a display comprising a display element having first and second display states, wherein the first and second display states differ in at least one optical property such that after any given element is driven to assume its first or second display state by an addressing pulse of finite duration, that state persists after termination of the addressing pulse for a time that is at least several times (e.g., at least four times) the minimum duration of the addressing pulse required to change the state of the display element. As shown in published U.S. Patent Application No. 2002/0180687 (see also corresponding International Application Publication No. WO 02/079869), some particle-based electrophoretic displays that support grayscale can be stable not only in their extreme black and white states but also in intermediate gray states, as can some other types of electro-optical displays. Such displays are properly referred to as "multistable" rather than bistable, but for convenience, the term "bistable" will be used herein to encompass both bistable and multistable displays.

Several types of electro-optical displays are known. One type of electro-optical display is a rotating two-color component type, such as described in U.S. Patent Nos. 5,808,783, 5,777,782, 5,760,761, 6,054,071, 6,055,091, 6,097,531, 6,128,124, 6,137,467 and 6,147,791 (although this type of display is commonly referred to as "rotating two-color ball" display, the term "rotating two-color component" is preferably more accurate because in some of the above-mentioned patents, the rotating component is not spherical). This display uses many little bodies (usually spherical or cylindrical) and internal dipoles, and the body includes two or more parts with different optical properties. These bodies are suspended in the cavity filled with liquid in the matrix, and the cavity is filled with liquid so that the body can rotate freely. The appearance of the display is changed by applying an electric field to the display, thereby rotating the body to various positions and changing which part of the body is seen through the viewing surface. This type of electro-optic medium is typically bistable.

Another type of electro-optical display uses an electrochromic medium, for example, an electrochromic medium in the form of a nanoelectrochromic film, which includes an electrode formed at least in part from a semiconducting metal oxide and a plurality of dye molecules attached to the electrode that are capable of reversible color change; see, for example, O'Regan, B. et al., Nature 1991, 353, 737 and Wood, D., Information Display, 18(3), 24 (March 2002). See also Bach, U. et al., Adv. Mater., 2002, 14(11), 845. Nanoelectrochromic films of this type are also described, for example, in U.S. Patent Nos. 6,301,038, 6,870,657, and 6,950,220. This type of medium is also typically bistable.

Another type of electro-optical display is the electrowetting display developed by Philips and described in Hayes, R.A. et al., "Video-Speed Electronic Paper Based on Electrowetting", Nature, 425, 383-385 (2003). It is shown in U.S. Patent No. 7,420,549 that such an electrowetting display can be made bistable.

Another type of electro-optical display, which has been the subject of intensive research and development for many years, is the particle-based electrophoretic display (EPD), in which multiple charged particles move through a fluid under the influence of an electric field. Compared to liquid crystal displays (LCDs), EPDs can offer good brightness and contrast, wide viewing angles, state bistability, and low power consumption. However, issues with the long-term image quality of these displays have prevented their widespread use. For example, the particles that make up EPDs tend to settle, resulting in a short lifespan for these displays.

As mentioned above, electrophoretic media require the presence of a fluid. In most prior art electrophoretic media, the fluid is a liquid, but electrophoretic media can be generated using a gaseous fluid; see, for example, Kitamura, T. et al., "Electronic toner movement for electronic paper-like display", IDW Japan, 2001, Paper HCS 1-1, and Yamaguchi, Y. et al., "Toner display using insulative particles charged triboelectrically", IDW Japan, 2001, Paper AMD4-4. See also U.S. Patents No. 7,321,459 and 7,236,291. When such gas-based electrophoretic media are used in an orientation that allows particle sedimentation, such as in signs where the media is arranged in a vertical plane, such gas-based electrophoretic media are susceptible to the same problems as liquid-based electrophoretic media due to particle sedimentation. In fact, the particle sedimentation problem in gas-based electrophoretic media is more severe than in liquid-based electrophoretic media because the viscosity of gaseous fluids is lower than that of liquids, which causes the electrophoretic particles to sediment faster.

A number of patents and applications assigned to or in the names of the Massachusetts Institute of Technology (MIT) and Ink have recently been published that describe encapsulated electrophoretic media. Such encapsulated media include a plurality of small capsules, each of which itself comprises an inner phase containing electrophoretically mobile particles suspended in a fluid, and a capsule wall surrounding the inner phase. Typically, the capsules themselves are held in a polymeric binder to form a coherent layer positioned between two electrodes. The techniques described in these patents and applications include:

(a) electrophoretic particles, fluids, and fluid additives; see, e.g., U.S. Patent Nos. 7,002,728 and 7,679,814;

(b) capsules, adhesives, and encapsulation processes; see, e.g., U.S. Patent Nos. 6,922,276 and 7,411,719;

(c) microcell structures, wall materials, and methods of forming microcells; see, e.g., U.S. Patent Nos. 7,072,095 and 9,279,906;

(d) Methods for filling and sealing microlocations; see, e.g., U.S. Patent Nos. 7,144,942 and 7,715,088;

(e) Films and subassemblies containing electro-optical materials; see, e.g., U.S. Patent Nos. 6,982,178 and 7,839,564;

(f) Backsheets, adhesive layers, and other auxiliary layers and methods for use in displays; see, e.g., U.S. Patent Nos. D485,294; 6,124,851; 6,130,773; 6,177,921; 6,232,950; 6,252,564; 6,312,304; 6,312,971; 6,376,828; 6,392,786; 6,413,790; 6,422,687; 6,445,374; 6,480,182; 6,498,114; 6,506,438; 6,518,949; 6,521,489; 6,535,197; 6,545,291; 6,639 ,578;6,657,772;6,664,944;6,680,725;6,683,333;6,724,519;6,750,473;6,816,147;6,819,471;6,825,068;6,831,769;6,842,167;6,842,279;6,842,657;6,865,010;6,873,452;6,909,532;6,967,640;6,980,196;7,012,735;7,030,412;7,075,703;7,106,296;7,110,163;7,116,31 8; 7,148,128; 7,167,155; 7,173,752; 7,176,880; 7,190,008; 7,206,119; 7,223,672; 7,230,751; 7,256,766; 7,259,744; 7,280,094; 7,301,693; 7,304,780; 7,327,511; 7,347,957; 7,349,148; 7,352,353; 7,365,394; 7,365,733; 7,382,363; 7,388,572; 7,401,758; 7,442,587; 7,492,497; ,535,624;7,551,346;7,554,712;7,583,427;7,598,173;7,605,799;7,636,191;7,649,674;7,667,886;7,672,040;7,688,497;7,733,335;7,785,988;7,830,592;7,843,626;7,859,637;7,880,958;7,893,435;7,898,717;7,905,977;7,957,053;7,986,450;8,009,344;8,027,081;8,049 ,947;8,072,675;8,077,141;8,089,453;8,120,836;8,159,636;8,208,193;8,237,892;8,238,021;8,362,488;8,373,211;8,389,381;8,395,836;8,437,069;8,441,414;8,456,589;8,498,042;8,514,168;8,547,628;8,576,162;8,610,988;8,714,780;8,728,266;8,743,077;8,754,85 9; 8,797,258; 8,797,633; 8,797,636; 8,830,560; 8,891,155; 8,969,886; 9,147,364; 9,025,234; 9,025,238; 9,030,374; 9,140,952; 9,152,003; 9,152,004; 9,201,279; 9,223,164; 9,285,648; and 9,310,661; and U.S. Patent Application Publication Nos. 2002/0060321; 2004/0008179; 2004/0085619; 2004/0105036; 2004/0 112525; 2005/0122306; 2005/0122563; 2006/0215106; 2006/0255322; 2007/0052757; 2007/0097489; 2007/0109219; 2008/0061300; 2008/0149271; 2009/0122389; 2009/0315044; 2010/0177396; 2011/0140744; 2011/0187683; 2011/0187689; 2011/0292319; 2013/0250397; 2013/0278900; 20 14/0078024; 2014/0139501; 2014/0192000; 2014/0210701; 2014/0300837; 2014/0368753; 2014/0376164; 2015/0171112; 2015/0205178; 2015/0226986; 2015/0227018; 2015/0228666; 2015/0261057; 2015/0356927; 2015/0378235; 2016/077375; 2016/0103380 and 2016/0187759; and International Patent Publication No. WO 00/38000; European Patent No. 1,099,207 Bl and 1,145,072 Bl;

(g) color formation and color adjustment; see, e.g., U.S. Patent Nos. 7,075,502 and 7,839,564;

(h) Methods for driving displays; see, for example, U.S. Patent Nos. 7,012,600 and 7,453,445;

(i) Display applications; see, for example, U.S. Patent Nos. 7,312,784 and 8,009,348; and

(j) Non-electrophoretic displays as described in U.S. Patent No. 6,241,921 and U.S. Patent Application Publication No. 2015/0277160, and applications of packaging and microcell technology other than displays; see, for example, U.S. Patent Application Publication Nos. 2015/0005720 and 2016/0012710.

Many of the aforementioned patents and applications recognize that the walls surrounding discrete microcapsules in encapsulated electrophoretic media can be replaced by a continuous phase, thereby creating so-called "polymer-dispersed electrophoretic displays," wherein the electrophoretic medium comprises a plurality of discrete droplets of electrophoretic fluid and a continuous phase of polymer material, and wherein the discrete droplets of electrophoretic fluid within such polymer-dispersed electrophoretic displays can be considered capsules or microcapsules, even though no discrete capsule membrane is associated with each individual droplet; see, for example, the aforementioned U.S. Patent No. 6,866,760. Therefore, for the purposes of this application, such polymer-dispersed electrophoretic media are considered a subclass of encapsulated electrophoretic media.

A related type of electrophoretic display is the so-called "microcell electrophoretic display." In a microcell electrophoretic display, charged particles and fluids are not encapsulated in microcapsules, but rather are held within a plurality of cavities formed within a carrier medium (typically a polymer film). See, for example, U.S. Patent Nos. 6,672,921 and 6,788,449, both assigned to Sipix Imaging.

Although electrophoretic media are typically opaque (because, for example, in many electrophoretic media, the particles substantially block visible light from being transmitted 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 display state is light-transmissive. See, for example, U.S. Patents Nos. 5,872,552, 6,130,774, 6,144,361, 6,172,798, 6,271,823, 6,225,971, and 6,184,856. Dielectrophoretic displays, which are similar to electrophoretic displays but rely on variations in electric field strength, can operate in a similar mode; see U.S. Patent No. 4,418,346. Other types of electro-optical displays can also operate in a shutter mode. Electro-optical media operating in a shutter mode can be used in a multilayer structure for a full-color display; in this structure, at least one layer adjacent to the viewing surface of the display is operated in a shutter mode to expose or conceal a second layer further from the viewing surface.

The subject matter described herein makes it possible to create a display device consisting of multiple electro-optical displays or display tiles. In some embodiments, the multiple electro-optical displays or display tiles can be electrophoretic image displays (EPIDs). The EPID 100 shown in Figure 1 can include a backplane 102 having a backplane pixel layer 108 including multiple pixel drive electrodes, a front electrode layer 104, and a display layer 106. The display layer 106 can include electrophoretic pigment particles encapsulated in microcapsules or microcups. Shown in Figure 1 are microcapsules including black and white electrophoretic pigment particles. The front electrode 104 can represent the viewing side of the EPID 100, in which case the front electrode 104 can be a transparent conductor, such as indium tin oxide (ITO) (which can be deposited onto a transparent substrate such as polyethylene terephthalate (PET) in some cases). In the display shown in Figure 1, the display layer 106 can be a particle-based medium including multiple microcapsules 110 between layers 104 and 108. Within each capsule 110 is a liquid medium and one or more types of colored pigment particles, including white pigment particles 112 and black pigment particles 114. An electric field (e.g., generated by electrodes on layers 108 and 104) can be used to control (move) pigment particles 112 and/or 114, thereby causing display 100 to operate as an electrophoretic display when addressed.

As indicated above, the subject matter presented herein provides a mounting structure for mounting an electro-optical display or display tile. The mounting structure may, in some embodiments, include a substrate for supporting a conductive interconnect layer. The substrate may be sufficiently flexible so that it can be rolled up or folded for transport. In some embodiments, the conductive interconnect layer may be printed. In some other embodiments, the conductive interconnect layer may be laser scribed or physically or mechanically etched, and the substrate may be designed to resist puncture cutting by the laser and prevent etching. In still other embodiments, the conductive interconnect layer may be produced separately from the mounting substrate and assembled at a later time. The mounting structure may also include an additional substrate for covering a printed pattern of the conductive interconnect layer. The printed pattern substrate may be made of paper or plastic to act as an electrical insulator to protect the conductive interconnect layer below.

In one embodiment, once the size and geometry of the display are determined, the arrangement of the display and driver unit can then be determined (e.g., drawn) on the mounting structure. To connect the display and driver unit, computer-aided design software (e.g., AUTOCAD (registered trademark) or Altium) can be used to draw marker traces. The drawn traces can then be used as a template to manufacture the conductive interconnects. To mask the conductive interconnects, a printed graphic layer can be placed on top of the conductive interconnects. Holes or vias can be cut through the printed graphic layer to allow access to the conductive interconnects. It should be appreciated that the conductive interconnects can be manufactured independently, separately from the other layers, and individually. In this way, the designer has the freedom to design and manufacture the conductive interconnects to any suitable size and configuration. Thus, the designer is not bound by the limitations of any conductive trace generation equipment, but is free to manufacture interconnects of any size and shape suitable for the designer's customization.

FIG2 shows a mounting structure 204 in which sixteen electro-optical displays or display tiles 202 can be assembled together to form a larger display device 200. In one example, display tiles 202 can be arranged in a rectangular array (e.g., 4x4) on the mounting structure 204 as shown in FIG2 , similar to how tiles are positioned on a wall, with uniform spacing between tiles. It should be appreciated that the rectangular shape of the display tiles 202 shown here is for schematic purposes only, as tiles 202 can easily be arranged in other geometric shapes. In addition, the subject matter disclosed herein enables display tiles 202 to be arranged and assembled in various configurations. In addition to the ordered stacking configuration shown in FIG2 , display tiles 202 can also be arranged, for example, with uneven spacing therebetween and in a disordered manner. In some embodiments, display tiles 202 can be arranged to form a predetermined image according to a specific form. Alternatively, a designer can arrange display tiles to form a specific pattern (e.g., abstract image, etc.) at will.

Additionally, each tile may be given a designated code to match a specific location on mounting structure 204. For example, a display tile (not shown) may be designated 1A to match predetermined location 1A on mounting structure 204, and the end user may simply match tile 1A with predetermined location 1A when assembling display device 200.

In some embodiments, the mounting structure 204 may include a substrate for supporting the conductive interconnect layer. The support substrate may be made of a plastic such as polyethylene terephthalate (PET) and have a thickness of at least 2 mils (51 μm - preferably 5 mils (127 μm) or greater) and be flexible enough to be rolled or folded. In some embodiments, the conductive interconnect layer may be scribed using an energy or particle (e.g., laser) beam, and the support substrate is preferably capable of withstanding cutting by the laser. The conductive interconnects (e.g., traces and/or pads) connecting the display tiles may sometimes be made by drawing the traces and/or pads between the tiles using a continuous conductor such as carbon black or a metal-filled ink. Alternatively, the interconnect traces or pads may be mechanically or laser scribed from a conductive layer made of a material such as indium tin oxide (ITO) or sputtered metal (e.g., aluminum). In another embodiment, the separate traces may be printed using a technique such as screen printing that may be suitable for high-volume applications, where the material processing fee and other startup costs may be amortized and reduced.

In addition, the mounting structure may also include another substrate for printing graphics, and the substrate may be arranged above the conductive interconnect layer. The printed graphics substrate layer may be made of paper or plastic and acts as an electrical insulator to protect the conductive interconnect layer below and also acts as a printing surface for the printed graphics. The printed graphics may be produced using ink jet or laser jet printing for unique customized designs or gravure printing for high-volume (non-customized) designs. The printed graphics may serve as alignment marks during installation and provide aesthetic appeal to the display device 200.

In order to assemble the display device 200, in a preferred embodiment, the designer can first determine the size and shape of the display tile 202. The designer can then decide the layout of each tile, and where the conductive interconnects can be arranged on each tile. The outline of the layout of the tiles 202 and their conductive interconnects can be drawn on the same layer as the printed graphics to simplify installation. Subsequently, the position of the driver unit of the display device can be determined. It is preferred that the driver unit is arranged behind one of the display tiles 202. In some embodiments, the display tile 202 can be bent outward away from the mounting structure 204, leaving space behind the tile for the driver unit. Alternatively, the driver unit can be arranged away from the tile 202, for example, hidden behind a housing (such as a baseboard molding), folded around the back of the mounting structure 204 (for example, above the top tile) or in a position that can be easily accessed by a display operator.

Once the arrangement of the display tiles 202 and driver units has been determined, marker traces connecting the driver unit outputs to the display tiles 202 can be drawn. CAD software such as AutoCAD, Altium, PADS, or Adobe Illustrator can be used to draw the marker traces. In some embodiments, fiducial marks can also be drawn to aid in later alignment of the printed graphics with the conductive interconnects (e.g., traces and/or pads). The drawn marker traces can then be used as a template to fabricate the conductive interconnects. Referring now to FIG3 , a conductive interconnect layer 300 for providing electrical connections to the display tiles is shown. The conductive interconnect layer 300 can be fabricated by printing the traces 302 and pads 304 on a dielectric substrate (e.g., PET) or by scribing a conductive film (e.g., carbon, silver, aluminum, ITO, etc.) already deposited on the dielectric substrate. Other methods of fabricating the conductive interconnect 300 may be employed depending on what manufacturing equipment is readily available to the user. Note that the conductive interconnect layer 300 can be fabricated separately from all other layers of the display device 100. In this way, the designer is free to use any method to create the interconnect layer 300 and is not bound by any interconnect production equipment. Therefore, the designer can make interconnects of any shape or size as he sees the assembly that fits his design. This allows the designer to freely create display devices of various shapes and configurations without being bound by the manufacturing limitations of conductive interconnects.

In use, each display tile may have a pre-assembled connector (e.g., a flat flexible connector) port, and a matching connector may be arranged on the pad 304. In this way, when assembling the display device, the user can simply connect the connector on each display tile to the matching connector on the pad 304, thereby eliminating the need to generate connecting cables to connect multiple display tiles to the mounting structure, which makes the entire device more compact and convenient to assemble.

Referring now to FIG. 4 , a printed graphic layer 400 is shown produced on a dielectric substrate that may later be laminated to the conductive interconnect layer 300 shown in FIG. On the printed graphic layer 400, the arrangement of the display tiles and driver units is outlined, along with through-holes 402 for the conductive interconnects. Furthermore, if multiple structures or surfaces are desired, fiducial or alignment marks may also be drawn on this layer to align adjacent interconnect mounting structures. For aesthetic purposes, other graphic features, such as artistic designs, may further be included. Once fabricated, through-holes or vias may be cut in this layer 400 to allow access to the conductive interconnects, where the driver units and display tiles may be connected. The through-holes may be fabricated using laser cutting, die cutters, scissors, or the like, depending on the designer's preference, and the electrical connections may be made using conductive pressure-sensitive adhesive pads, spring pins, or electrical connections, such as a crimp pin/socket pair (i.e., Nicomatic).

In a preferred embodiment, the printed graphics and conductive interconnects can be adhered (e.g., laminated) together or separately to a supporting substrate to create a monolithic mounting structure or surface. The display tiles can then be positioned onto the mounting structure at their intended locations. Optionally, a mounting frame can also be provided, to which the mounting structure and display tiles can be attached.

In addition, the subject matter presented herein also provides a display tile connected to the mounting structure 200 presented in Figure 2. The exemplary display tile may include a pixel conductor layer, a substrate layer, and a reverse conductor layer, wherein the substrate layer may be located between the pixel conductor layer and the reverse conductor layer. The drive electrodes of the display pixels or pixel segments may be defined and manufactured on the pixel conductor layer. In a preferred embodiment, the drive electrodes are first patterned (e.g., laser scribing) on the pixel conductor layer using an energy or particle beam, wherein the laser scribing allows the manufacture of drive electrodes of various sizes and geometries without the use of complex machinery. Subsequently, through holes may be created through the substrate layer, and conductive traces may be drawn on the reverse conductor layer, wherein the conductive traces are used to transmit a voltage or drive waveform to the drive electrodes through the through holes. In this way, the backplane is assembled without having to use size-limiting techniques, such as photolithography or global alignment, which are typically required for screen printing or PCB manufacturing. Therefore, large-scale backplanes with drive electrodes of variable sizes can be assembled conveniently and inexpensively.

In some embodiments, specialized display applications will require a display to use pixels or pixel segments of irregular geometries. The present subject matter enables the assembly of display tiles having multiple irregularly shaped display pixel segments at an affordable price. Figure 5 shows a pixel conductor layer 500 of a display tile having multiple irregularly shaped pixel segments. As shown in Figure 5, the pixel conductor layer 500 may include multiple variable-sized drive electrodes 511-517 for driving multiple irregularly shaped pixel segments (not shown), wherein the shape and position of the drive electrodes 511-517 will match the shape and position of the corresponding pixel segments. In some embodiments, the pixel conductor layer 500 can be formed by applying a continuous layer of a conductive material such as ITO to a substrate. Other conductive materials can also be sputtered onto the substrate to form a continuous layer, such as but not limited to various types of conductive oxides, gold, inert metals, nickel boron, carbon, carbon nanotubes, graphene, and poly (3,4-ethylenedioxythiophene) or also known as PEDOT. In some other embodiments, conductive materials such as copper, nickel, aluminum, silver nanowires, and printed silver may also be used depending on the specific needs of the display application.

According to some embodiments of the present subject matter, the display tile assembly process may include subjecting a continuous layer of conductive material to laser scribing to pattern drive electrodes 511-517 of various shapes. The scribing may cut deep enough into the layer of conductive material to electrically isolate each drive electrode, but not so deep as to cut through the underlying substrate or substantially weaken the substrate so that it becomes brittle. Laser scribing allows patterning of drive electrodes of various geometric configurations without having to perform photolithography or global alignment, which may be prohibitively expensive for large-sized displays. Figure 5 also shows a star-shaped drive electrode 520 and a circular drive electrode 522, but it will be appreciated that other geometric shapes may be readily patterned using laser scribing or other comparable etching methods commonly employed in the industry.

Once the drive electrodes have been patterned, through-holes may be created through the substrate to connect the drive electrodes to a driver circuit (not shown). FIG6 illustrates an exemplary substrate layer 600 according to the subject matter presented herein. In some embodiments, the substrate layer 600 may be manufactured using materials such as PET, polyethylene naphthalate (PEN), cyclic olefins, paper, fabric, polyimide, or polycarbonate. In order to provide electrical connections to the drive electrodes 511-517 as shown in FIG5 , one or more through-holes 621-627 may be created through the substrate layer 600 for each drive electrode 511-517. Through-holes 621-627 may be created by cutting through the substrate layer 600 using a laser, but it will be appreciated that mechanical drilling or other puncture methods commonly used in the art may be readily employed. In some embodiments, the through-holes cut into the drive electrodes may be at least 200 μm in diameter and typically no greater than 3 mm to minimize the appearance of the holes in the final display. It will be appreciated that in other embodiments, the through-holes may be formed before the drive electrodes are patterned, for example the substrate may be pre-fabricated with through-holes in appropriate locations configured for backplane assembly.

Once the vias 621-627 are created, a porous paper behind the substrate and a vacuum pull on the porous paper can be used to disperse conductive material (not shown) into the vias 621-627. The vacuum force will pull the conductive material through the vias 621-627 and plate the sides of the vias 621-627 or fill the volume of the vias 621-627, connecting the drive electrodes 511-517 to the reverse side of the substrate 600. Preferably, the completed vias have surfaces that are coplanar with both the pixel conductor layer and the reverse conductor layer to avoid ridges from too much filler or lamination voids caused by insufficient via filling. In some embodiments, the vias 621-627 can be filled with a hot melt adhesive having a melting temperature around the lamination temperature of the electrophoretic ink material (e.g., 250F), as long as the flow viscosity of the hot melt adhesive is low enough to prevent the ink capsules from rupturing.

Appropriately filled vias 621-627 can provide electrical connections between the drive electrodes 511-517 and the conductive traces formed on the reverse side (i.e., the side opposite the pixel conductor layer) of substrate 600. Prior to the formation of the conductive traces, in some embodiments, an ink FPL stack (not shown) can first be laminated to the drive electrodes 511-517. This is done in such a way that the thickness of the traces will not press through substrate 600 and create indentations in the FPL layer during lamination.

The subsequent formation of the conductive traces can be accomplished in various ways. In some embodiments, the conductive traces can be printed onto the reverse side starting at the through-hole and extending according to a predetermined layout for routing all lines from the pixel position to a gathering area without crossing, which matches the pad spacing of the electronic device to be attached to the device. The printing of the conductive traces can be done manually for a small number of backplane units, or alternatively, an XY plotter with controlled distribution of printable conductive material can be used. Camera vision alignment can be used to locate the through-hole, and the XY plotter can be aligned with that position to begin drawing the conductive traces. It should be recognized that other trace generation methods commonly used in this industry can be conveniently adopted, such as, but not limited to, inkjet using conductive ink, rollers, belts, etc. Some examples of suitable trace materials are printing inks filled with silver or carbon. In this way, global alignment may not be required to create the conductive traces. For example, local alignment may be completely sufficient to arrange the traces to connect the through-hole to the driver circuit. Large size backplanes (eg, backplanes larger than 24 inches by 48 inches in size) may be conveniently assembled by not having to perform global alignment, which can be difficult to design and expensive to perform.

In some other embodiments, the conductive traces may be manufactured (eg, printed) as a conductive interconnect layer. The conductive interconnect layer may be produced separately from the substrate 600 and the pixel conductor layer 500 and assembled together when the display tiles are assembled.

Alternatively, the conductive traces can be etched or scratched into a continuous conductive layer, similar to the patterning of the drive electrodes 511-517 mentioned above. In some embodiments, a continuous layer of conductive material can be applied to the reverse side of the substrate 600. After the FPL stack is laminated to the drive electrodes 511-517, a laser can be used to etch the conductive traces into the continuous conductive layer so that each conductive trace is electrically isolated but does not cut deep enough into the substrate to cut through or render it fragile. Figure 7 shows an exemplary reverse conductor layer 700 with conductive traces 701-707. The conductor layer 700 can be created as a printed layer of conductive circuitry or by etching into a continuous layer of conductive material. In the case where it is created by etching, the cutting of each conductive trace can include a through hole for the drive electrode and a circular structure around the through hole, which increases the width of the conductive trace around each through hole to ensure continuity for that drive electrode. Alignment with each through hole can be accomplished using a camera vision alignment system to find and align each through hole to locate the conductive trace path. Conductive traces 701-707 may extend in a predetermined layout for routing all lines from the pixel locations to one collection area without crossing, which matches the pad pitch of the electronics to be attached to the device.

For conductive fabric designs, it may be convenient to first create the pattern of drive electrodes and conductive traces and then adhere them to a substrate, which can be a fabric or film, depending on the needs of the display application. Other suitable substrate materials include PET, polyethylene naphthalate (PEN), cyclic olefins, paper, fabric, polyimide, or polycarbonate.

In general, changes can be made to the backplane assembly process described above while still producing a backplane that is substantially comparable in performance. For example, a roll-to-roll machine can be used to assemble backplanes according to the subject matter presented herein. In some embodiments, a continuous roll of substrates coated with conductive material can be processed at multiple assembly stations including a laser cutting/etching station and an XY plotter station, both equipped with a camera vision alignment system. These two stations can be different units or can be part of a single assembly station (for example, the laser cutter and plotter can be part of an XY gantry system). In addition, the roll-to-roll machine can also include a station for heated lamination of ink FPL or other materials for assembling the display unit. This arrangement can be advantageous at least because the conductive traces can now be radiation cured (for example, UV cured) at the roll-to-roll machine, which saves production time and cost by not having to use conventional heated drying ovens.

In another embodiment, the vias can be cut with the substrate roll prior to deposition of the conductive material, which allows the vias to be filled with the deposited conductive material. In this way, a separate assembly step for filling the vias can be eliminated, further reducing production costs.

In yet another embodiment, the vias may be left unfilled prior to lamination of the FPL to the display stack.Subsequent distribution of conductive traces to the reverse side of the substrate may actually implement the vias to provide connections between the drive electrodes and the conductive traces.

It will be appreciated that flexible materials can be used to create the pixel conductor layer, substrate layer, and reverse conductor layer proposed above, resulting in a bendable or flexible display tile. Furthermore, the flexible nature and robustness of the electrophoretic material enable the display tile to be not only flexible, but also capable of having multiple curvatures. FIG8A illustrates one such flexible display tile 800. The display tile 800 shown here can be sufficiently flexible to bend into a semicircular shape, wherein the front electrode 804 of the tile 800 can be created using flexible materials commonly used in the industry. The pixel conductor layer 808, substrate layer 810, and reverse conductor layer 812 can all be made of materials that are flexible enough to support the electrophoretic display material layer 806. The curved shape of the display tile 800 creates a space 814 adjacent to the reverse conductor layer 812, so that when assembled into a mounting structure similar to that shown in FIG2 , a controller device (e.g., a display controller or control circuit) can be located or accommodated in that space 814, out of sight and maintaining the overall compactness of the overall display device.

In another embodiment shown in FIG8B , the flexible display tile 802 can include multiple curvatures. The multiple layers of the display tile 802 (e.g., the front electrode 816, the electrophoretic material layer 816, the pixel conductor layer 820, the substrate layer 822, and the back conductor layer 824) can be flexible enough to exhibit various curvatures to suit the designer's needs.

FIG9 shows a flexible display tile 908 similar to the display tile presented in FIG8B assembled onto a mounting structure 900. As discussed above, the mounting structure 900 may include a conductive interconnect layer 904 having conductive traces for providing electrical connections to the display tile 908. A printed graphic layer 902 may be located between the interconnect layer 904 and the display tile 908 for insulation. Connectors 906 may be used to connect the display tile 908 to the interconnect layer 904. The connectors 906 may have short wires for flexibility, or may be snap-on type connectors or any connector commonly used in the industry, eliminating the need for a user to use cables to connect individual tiles to the mounting structure.

From the foregoing, it will be seen that the present invention provides a means for inexpensive customization and quick turnaround manufacturing of tiled display systems or devices. The present invention eliminates the need for labor-intensive custom cable manufacturing and greatly simplifies the installation process. The subject matter described herein also eliminates the need for cable management and improves the aesthetics of the entire installation process. The overall thickness of the display device is also reduced because additional space is no longer required to route cables behind the display tiles. Furthermore, the present invention allows the tiles to be arranged independently of each other because the electrical connections are hidden behind the printed graphic layer.

It will be apparent to those skilled in the art that many changes and modifications may be made to the particular embodiments of the invention described above without departing from the scope of the invention. Therefore, the entire foregoing description should be interpreted in an illustrative sense rather than a limiting sense.

Claims (8)

1. A method for producing a display device having a plurality of display surfaces controlled by a controller, the method comprising: A mounting structure is provided having predetermined positions for mounting the plurality of display surfaces; A conductive interconnect layer is generated having multiple traces configured to connect the plurality of display surfaces to the controller; At least one display surface is mounted to the mounting structure, the at least one display surface being sufficiently flexible to have curvature such that the curvature creates a space between the at least one display surface and the mounting structure; The controller is arranged in the space between the at least one display surface and the mounting structure; and The display surface is an electro-optic display, and The mounting structure includes the conductive interconnect layer and a printed pattern layer that covers the conductive interconnect layer and is located between the plurality of display surfaces and the conductive interconnect layer. 2. The method of claim 1, wherein the printed pattern layer is an insulating layer such that the interconnect layer is insulated from the at least one display surface. 3. The method of claim 1, wherein the step of generating the conductive interconnect layer further comprises etching the interconnect layer to generate conductive traces. 4. The method of claim 1, wherein the installation step further comprises using a connector to connect the mounting structure and the plurality of display surfaces. 5. The method of claim 4, wherein the step of generating the conductive interconnect layer further comprises using a laser to generate conductive traces. 6. A display device having a plurality of display surfaces controlled by a controller, the display device comprising: A mounting structure for mounting the plurality of display surfaces, the mounting structure having a conductor layer for providing electrical connections to the plurality of display surfaces; and At least one display surface, which is sufficiently flexible to have curvature, wherein the curvature creates a space between the at least one display surface and the mounting structure to accommodate the controller; and The display surface is an electro-optic display, and The mounting structure further includes a printed graphic layer that covers the conductor layer and is located between the display surface and the conductor layer. 7. The display device of claim 6, wherein the mounting structure is flexible. 8. The display device of claim 6, wherein the at least one display surface includes a flexible front electrode.