Stretchable electro-optic display

Abstract

Stretchable electro-optic displays include a layer of electrically conductive material and an electrophoretic medium laminated to the layer of electrically conductive material. The layer of electrically conductive material also includes a plurality of nodes and a stretchable interconnect connecting a first and a second node of the plurality of nodes. Methods of making stretchable electro-optic displays are also provided, including patterning a layer of electrically conductive material to define a plurality of nodes and a stretchable interconnect connecting a first and a second node of the plurality of nodes, and laminating a layer of electrophoretic medium to the layer of electrically conductive material.

Description

[0001] This application is a divisional application of the application patent application with the priority date of 31 May 2016, application number 201780027046.4, entitled "Stretchable electro-optic display".

[0002] Cross Reference to Related Applications

[0003] This application claims priority to and the benefit of U.S. provisional application 62 / 343,775 filed May 31, 2016, the contents of which are incorporated herein in their entirety. TECHNICAL FIELD

[0004] The present invention relates to electro-optic displays and related apparatus and methods. More particularly, in one aspect, the present invention relates to stretchable electro-optic displays. BACKGROUND

[0005] The term "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 between the two states by application of an electric field to the material. Although the optical property is typically color, it can be another optical property, such as optical transmission, reflectance, luminescence, or, where the display is for machine reading, reflectivity of electromagnetic wavelengths outside the visible range.

[0006] The term "gray state" is used herein in its conventional meaning in the imaging art to refer to an intermediate optical state of a pixel between its two extreme optical states when the change in optical state is a change in gray level. The gray state is not necessarily a neutral state: when a pixel is in a gray state that is halfway between its two extreme states, the gray state will also typically be an intermediate color halfway between the first and second colors, which are the colors in the two extreme states. Thus, the use of the term color gray state herein does not mean a neutral color but a color halfway between two colors. Also, the extreme states can be referred to as color states in this context.

[0007] The terms "bistable" and "bistability" as used herein refer to displays comprising display elements having first and second display states differing in at least one optical property, and such that after any given element has been driven to assume its first or second display state by an addressing pulse of finite duration, the state will persist for at least a minimum duration of the addressing pulse, for example, at least 4 times the addressing pulse duration, in the absence of further addressing pulses. Some particle-based electrophoretic displays are capable of displaying gray scales, for example, as described in U.S. Patents Nos. 7,170,670 and 7,202,847. Although the terms "bistable" and "bistability" as used herein can, for convenience, be used in the context of a display having only two display states, for example, black and white, these terms are also, preferably, taken to include the case where the display has more than two display states.

[0008] One type of electro-optic display that has been the subject of intense research and development efforts for many years is the electrophoretic display, in which a plurality of charged particles move through a fluid under the influence of an electric field. Electrophoretic displays can have the properties of good brightness and contrast, wide viewing angles, state bistability, and low power consumption, when compared with liquid crystal displays. However, these displays are not suitable for all applications. For example, the long response times of current electrophoretic displays make them unsuitable for applications in which the display is frequently updated, such as in the display of still pictures.

[0009] Numerous patents and applications assigned to, or in the public domain of, the Massachusetts Institute of Technology (MIT) and E Ink Corporation have described various technologies for encapsulating electrophoretic media and other electro-optic media. Such encapsulated media comprise a plurality of microscopic capsules, each of which itself comprises an inner phase including a fluid and a plurality of electrically charged particles suspended in the fluid, and an envelope surrounding the inner phase. Typically, the capsules themselves are preserved in a polymer binder. The technologies described in these patents and applications include:

[0010] (a) Electrophoretic particles, fluids and fluid additives; see for example U.S. Patents Nos. 7,002,728 and 7,679,814;

[0011] (b) Capsules, binders and encapsulation processes; see for example U.S. Patents Nos. 6,922,276 and 7,411,719;

[0012] (c) Films and sub-assemblies containing electro-optic materials; see for example U.S. Patents Nos. 6,825,829; 6,982,178; 7,236,292; 7,443,571; 7,513,813; 7,561,324; 7,636,191; 7,649,666; 7,728,811; 7,729,039; 7,791,782; 7,839,564; 7,843,621; 7,843,624; 8,034,209; 8,068,272; 8,077,381; 8,177,942; 8,390,301; 8,482,835; 8,786,929; 8,830,553; 8,854,721; and 9,075,280; and U.S. Patent Application Publication Nos. 2009 / 0109519; 2009 / 0168067; 2011 / 0164301; 2014 / 0027044; 2014 / 0115884; and 2014 / 0340738;

[0013] (d) Backplanes, adhesive layers and other auxiliary layers for displays and methods; see for example U.S. Patents Nos. 7,116,318 and 7,535,624;

[0014] (e) Color formation and color adjustment; see for example U.S. Patents Nos. 7,075,502 and 7,839,564;

[0015] (f) Methods for driving displays; see for example U.S. Patents Nos. 7,012,600 and 7,453,445;

[0016] (g) Applications of displays; see for example U.S. Patents Nos. 7,312,784 and 8,009,348; and

[0017] (h) Non-electrophoretic displays, as described in U.S. Patents Nos. 6,241,921; 6,950,220; 7,420,549; 8,319,759; and 8,994,705; and U.S. Patent Application Publication No. 2012 / 0293858.

[0018] All patents and applications cited herein are incorporated by reference in their entirety.

[0019] Many of the above patents and applications recognize that walls surrounding discrete microcapsules can be replaced by a continuous phase, thus producing a so-called polymer-dispersed electrophoretic display, in which the electrophoretic medium comprises a plurality of discrete droplets of an electrophoretic fluid and a continuous phase of a polymeric material. For purposes of the present application, such a polymer-dispersed electrophoretic medium is regarded as a sub-category of encapsulated electrophoretic media, as the discrete droplets of electrophoretic fluid in such a medium are themselves regarded as capsules or microcapsules, even though the membrane surrounding each individual droplet is not associated with any single individual liquid droplet; see for example the aforementioned US Patent No. 6,866,760. Therefore, for purposes of the present application, such a polymer-dispersed electrophoretic medium is regarded as a sub-category of encapsulated electrophoretic media.

[0020] A related type of electrophoretic display is a so-called "microcell electrophoretic display". In a microcell electrophoretic display, the charged particles and the fluid are not encapsulated within microcapsules, but instead are maintained as a plurality of small discrete articles, called microcells, in a host medium, typically a solid matrix. See for example U.S. Patents Nos. 6,672,921 and 6,788,449, issued to Sipix Imaging, Inc.

[0021] Although the electrophoretic medium has sometimes been referred to as a fluid, this is not intended to exclude the possibility that the medium can contain solid particles, such as the particles of the aforementioned polymer-dispersed electrophoretic medium. Although the electrophoretic medium is often opaque, as is the case with most electrophoretic displays, it can in some cases be transparent, as is the case with some of the displays described below. Although the electrophoretic medium has sometimes been referred to as a fluid, this is not intended to exclude the possibility that the medium can contain solid particles, such as the particles of the aforementioned polymer-dispersed electrophoretic medium. Although the electrophoretic medium is often opaque, as is the case with most electrophoretic displays, it can in some cases be transparent, as is the case with some of the displays described below. Although the electrophoretic medium has sometimes been referred to as a fluid, this is not intended to exclude the possibility that the medium can contain solid particles, such as the particles of the aforementioned polymer-dispersed electrophoretic medium. Although the electrophoretic medium is often opaque, as is the case with most electrophoretic displays, it can in some cases be transparent, as is the case with some of the displays described below. Although the electrophoretic medium has sometimes been referred to as a fluid, this is not intended to exclude the possibility that the medium can contain solid particles, such as the particles of the aforementioned polymer-dispersed electrophoretic medium. Although the electrophoretic medium is often opaque, as is the case with most electrophoretic displays, it can in some cases be transparent, as is the case with some of the displays described below.

[0022] Preparation of a three-layer electro-optic display typically involves at least one lamination operation. For example, in several of the MIT and E Ink patents and applications noted above, methods for preparing encapsulated electrophoretic displays are described in which an encapsulated electrophoretic medium comprising capsules in a binder is coated onto a flexible substrate comprising indium tin oxide (ITO) or a similar conductive coating on a plastic film (which serves as one electrode of the final display), the capsule / binder coating is dried to form an adherent layer of electrophoretic medium firmly adhered to the substrate. A backplane is separately prepared, comprising an array of pixel electrodes and appropriate conductor arrangements to connect the pixel electrodes to drive circuitry. To form the final display, the substrate with the capsule / binder layer is laminated to the backplane using a lamination adhesive (using a very similar process, a display can be prepared for use with a stylus or similar movable electrode, which can slide over a simple protective layer such as a plastic film, by replacing the backplane with a simple protective layer such as a plastic film). In one preferred form of this method, the backplane itself is flexible, and is prepared by printing the pixel electrodes and conductors on a plastic film or other flexible substrate. The established lamination technique for preparing displays on a large scale by this method is roll lamination using a lamination adhesive. Similar preparation techniques can be used for other types of electro-optic display. For example, microcell electrophoretic media or rotating bichromal member media can be laminated to a backplane in essentially the same way as an encapsulated electrophoretic medium.

[0023] In certain applications, it can be desirable to have a stretchable electro-optic display; however, conventional electro-optic displays include one or more layers that can prevent the display from being stretched, even if the display is flexible. For example, consider an electro-optic display having a front electrode and a back electrode on either side of the electro-optic layer, the front electrode and / or the back electrode can be formed of a rigid and stretch-resistant material, such as indium tin oxide (ITO). Typically, a flexible display can only be able to bend in a single axis curve, in the same way that a sheet of paper can be bent, because stretching can be limited by the layer within the electro-optic display that is most limited. Thus, there is a need for an electro-optic display that is both flexible and stretchable. SUMMARY

[0024] One aspect of the present application provides an electro-optic display comprising a layer of electrically conductive material and an electrophoretic medium laminated to the layer of electrically conductive material. The layer of electrically conductive material can further comprise a plurality of nodes and a stretchable interconnect connecting a first and a second node of the plurality of nodes.

[0025] In another aspect of the present application, a method of preparing an electro-optic display comprises patterning a layer of electrically conductive material to define a plurality of nodes and a stretchable interconnect connecting a first and a second node of the plurality of nodes, and laminating a layer of electrophoretic medium to the layer of electrically conductive material.

[0026] These and other aspects of the present application will be apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various aspects and embodiments of the present application will be described with reference to the following drawings. It should be understood that the drawings are not necessarily drawn to scale. The drawings describe one or more embodiments of the present invention by way of example only and not by way of limitation. In the accompanying drawings, the same reference numerals represent the same or similar elements.

[0028] Figure 1 is a cross-sectional view of an example of an electro-optical display.

[0029] Figure 2 is a schematic diagram illustrating an exemplary method for forming a display capable of conforming to a shape having a compound curve.

[0030] Figure 3A is a schematic diagram illustrating an exemplary display layer structured to stretch in one or more directions.

[0031] Figure 3B It shows that Figure 3A Schematic diagram of an exemplary cross-sectional view of a display showing the display layers shown in .

[0032] Figure 3C It shows Figure 3A Schematic diagram showing the stretched state of the display layer shown in .

[0033] Figure 4 is a schematic diagram illustrating an exemplary display layer structured to stretch in one or more directions according to a non-limiting embodiment.

[0034] Figure 5 is a schematic diagram illustrating an exemplary display layer structured to stretch in one or more directions according to a non-limiting embodiment.

[0035] Figure 6A is a schematic diagram illustrating an exemplary display layer structured to stretch in one or more directions according to a non-limiting embodiment.

[0036] Figure 6B yes Figure 6A An enlarged version of the schematic diagram. DETAILED DESCRIPTION

[0037] In the following detailed description, numerous specific details are set forth by way of examples to provide a thorough understanding of the relevant teachings. However, it is apparent to one skilled in the art that the present teachings can be practiced without these details.

[0038] Referring generally to the figures, various embodiments of the present application provide electro-optic displays that include a layer having a plurality of nodal regions (also referred to herein simply as "nodes") with an extendable interconnection between at least two nodes. While the material of the layer can be inextensible or have limited extensible properties, the shape of the extendable interconnection can enable the extension of the layer. The extendable interconnection can be serpentine, coiled, zigzag, curved, or other shape such that it can expand and contract when manipulated appropriately. In this way, the distance between nodes connected by the extendable interconnection can be changed by manipulating (e.g., pulling) the display. As the nodes are pulled apart, the serpentine interconnection will rotate and flex. The flexibility and extensibility of the display can enable the display to conform to a variety of shapes, including shapes having one or more compound curves. In some embodiments, the electro-optic display is an electrophoretic display and the layer having nodes and an extendable interconnection is an electrode of the display.

[0039] Various features of the displays can facilitate their use for beneficial purposes, such as in architectural displays and wearable displays. One such feature is the ability of the displays to stretch in one or more directions. While the flexibility of a display relates to the ability of the display to bend, the extensible nature of a display includes the ability of the display to elongate and extend to cover more surface area. The flexibility of a display, in combination with its extensible properties, enables the display to bend and / or conform to three-dimensional shapes. An extensible display can be formed by configuring the display such that portions of the display are configured to stretch. Other portions of the display can remain continuous as nodes connected by the extendable interconnection. By extending the interconnection, the distance between adjacent nodes can be increased such that the area occupied by the display surface is increased. In some embodiments, the extendable interconnection and the flexibility of the display enable the display to conform to shapes having one or more compound curves. Another feature relates to the ability to design and structure electro-optic displays to include extendable interconnections in one or more layers of the display. The electro-optic display layers can be structured to be extensible using any suitable technique (e.g., cutting with a laser cutter or scissors). The resolution of the technique can determine the size of the nodes and the extendable interconnection. Another feature relates to the ability to control the electro-optic display by creating colors, patterns, or other visual effects through the use of drive signals.

[0040] Aspects of the present application relate to ways of designing and structuring electro-optic displays to be stretchable. An electro-optic display can include an electro-optic medium between a front electrode and a back electrode. In some embodiments, the electro-optic display can have segmented electrodes, and in other embodiments, the electro-optic display can be configured to have an active matrix of pixels. Applicant has realized that the properties of the materials used in electro-optic displays can limit the ability of the display to stretch, thereby limiting the types of shapes that the electro-optic display can form. Accordingly, some aspects of the present application provide one or more layers of an electro-optic display with stretchable interconnects that can improve the ability of the display to stretch and conform to different shapes. In some embodiments, the interconnects can be shaped to reduce the strain of the materials in the display layer when the interconnects are elongated to a stretched state. In some embodiments, the width of the stretchable interconnects can have a substantially uniform size along the length of the stretchable interconnects. Additionally, the stretchable interconnects can be structured to increase the effective area of the display while still providing the display with stretchable capabilities.

[0041] The various aspects described above, and other aspects, will now be described in more detail below. It should be understood that these aspects can be used alone or in any combination with two or more of the other aspects, unless they are mutually exclusive.

[0042] In some embodiments, the stretchable display can be an electrophoretic display. Figure 1 A cross-sectional view of an example electrophoretic display construction is shown in FIG. 1. The display 100 includes an electrophoretic medium layer 101 that can include a plurality of capsules 104 having a suspending fluid and electrophoretic particles 106 suspended in the fluid. The electrophoretic medium layer 101 is between an electrode 102 and an electrode 110. The electrophoretic particles 106 can be charged and respond to electric field differences created by the electrode 102 and the electrode 110. Examples of suitable electrophoretic medium layers are described in U.S. Patent Nos. 6,982,178 and 7,513,813. In some embodiments, the electrophoretic medium layer can be relatively more stretchable than other layers in the display, such as the electrode 102 and the electrode 110, and a stretchable display can be formed by structuring the other layers to include stretchable interconnects. In this way, all of the layers of the display can be made to stretch.

[0043] The two electrodes can be described in terms of a viewing face of the display. For example, if the surface of the display 100 proximate to the electrode 102 is the viewing face, then the electrode 102 can be referred to as the front electrode and the electrode 110 can be referred to as the back electrode. The electrode 102 and / or the electrode 110 can be optically transparent. The electrode 102 can be a single common transparent electrode on one side of the electrophoretic medium layer 101 that extends the length of the display. The electrode 110 is on the side of the electrophoretic medium layer 101 opposite the electrode 102. In some embodiments, the electrode 110 can also be a common electrode like the electrode 102, extending the length of the display 100. Alternatively, the electrode 110 can be pixelated to define the pixels of the display.

[0044] The display 100 also includes a voltage source 108 coupled to the electrodes 102 and 110 and configured to provide drive signals to those electrodes. The voltage provided then creates an electric field between the electrodes 102 and 110. Thus, the electric field experienced by the electrophoretic medium layer 101 can be controlled by varying the voltage applied to the electrodes 102 and 110, and in the case where one or both of those electrodes are pixelated, varying the voltage applied to a desired pixel can provide control of the display pixel. The particles 106 within the electrophoretic medium layer 101 can move within their respective capsules 104 in response to an applied electric field resulting from the voltage difference between the electrodes 102 and 110.

[0045] Even though the material forming the electrodes is not inherently stretchable, the electrodes 102 and / or 110 can be structured to include stretchable interconnections to provide stretchable capabilities to the display 100. For example, the electrode 102 and / or the electrode 110 can be formed of indium tin oxide (ITO), which has limited stretch properties, but by structuring the electrode 102 and / or 110 to have stretchable interconnections, the stretch properties of the electrode 102 and / or 110 can be improved. Additionally, the electrode 102 and / or the electrode 110 can be flexible, providing flexibility to the display 100. For example, ITO can be flexible at appropriate thin dimensions. Thus, in some embodiments, the electrode 102 and / or the electrode 110 can be a thin layer of ITO. In such cases, the ITO can be less than, for example, 15 mils, less than 10 mils, or any value within those ranges, or any other value that provides the desired flexibility in those cases where a flexible display is desired. In those cases where the electrode 102 represents the viewing side of the display 100, using ITO as the electrode 102 can be beneficial because ITO electrodes can be transparent. Additionally, other electrode materials can be used as alternatives.

[0046] Electrodes 102 and / or 110 can each optionally be formed on a substrate, such as a substrate of polyethylene terephthalate (PET). Such a substrate can be transparent, thus not negatively impacting the display performance of display 100. As with electrodes 102 and 110 themselves, any substrate for the electrodes can be formed of a material and structured with stretchable interconnections that provide the desired stretchability. Similar dimensions to those listed above for electrodes 102 and 110 can be used for any substrate to provide the desired display flexibility. For ease of illustration, the substrate is not shown separately in Figure 1

[0047] While Figure 1 A microencapsulated electrophoretic display is shown, but various types of displays can be used in accordance with the techniques described in this application. In general, electro-optic displays including microencapsulated electrophoretic displays, microcell electrophoretic displays and polymer-dispersed electrophoretic image displays (PDEIDs) can utilize aspects of this application. Furthermore, while electrophoretic displays represent a suitable type of display in accordance with aspects of this application, other types of displays can also utilize one or more aspects of this application. For example, Gyricon displays, electrochromic displays and polymer dispersed liquid crystal displays (PDLCDs) can also utilize aspects of this application.

[0048] The electro-optic displays described herein can have any suitable size, and in some embodiments can be small. For example, display 100 can be small in at least some embodiments, which can facilitate its flexible nature. For example, each of electrodes 102 and 110 can be between 1 mil (thousandth of an inch) and 10 mils, such as 5 mils each, or between 0.1 mm and 0.5 mm. The electrophoretic medium layer can be between 0.5 mil and 5 mils, such as 1 mil, or between about 0.03 mm and 0.06 mm. Thus, in some embodiments, display 100 can have a total thickness of about 10-15 mils, or about 0.2 mm to 0.4 mm. The listed dimensional examples are non-limiting, as other dimensions can be used.

[0049] ​As described above, some or all layers in an electrophoretic display can be structured to have stretchable interconnections. Since continuous layers may limit the overall stretching properties of a display, structuring the layers to have stretchable interconnections can improve the ability of the display to stretch. In some embodiments, the material forming the display layer may be relatively inextensible, but the layer may be structured to have stretchable interconnections, for example, by suitable patterning of the layer. A stretchable electrode layer (e.g., an electrode layer formed of ITO and appropriately patterned) can be structured to have nodes connected by stretchable interconnections, while other layers of the display, such as the electrophoretic medium layer, are continuous. In some embodiments, an inextensible base material (e.g., PET) can be structured into a display layer to have nodes connected by stretchable interconnections. In some embodiments, all layers in the display can be configured to have nodes connected by stretchable interconnections. Such a display can have openings passing through all layers of the display so that the display is used for the desired purpose of the opening in the display, including applications in wearable displays, where the display is worn by a person and the opening provides a passage for air and moisture, achieving breathability similar to fabric. In some embodiments, the display can include an elastomer, such as an elastomer film layer. The elastomer can provide mechanical structure to the display and / or protect the structuring of one or more layers with stretchable interconnections. The elastomer can optionally be optically obscured by incorporating scattering fillers or textured surfaces of the elastomer layer to hide the cut lines defining the interconnections, which can improve the readability of the electro-optical display. Various aspects of the present application relate to ways of structuring display layers to be stretchable and forming stretchable displays of the type described herein. Figure 2 An exemplary method 200 for forming a stretchable display according to aspects of the present application is shown. The method 200 begins with operation 202 of structuring one or more layers of an electro-optical display to have any suitable configuration of nodes and stretchable interconnects, examples of which are described in detail in FIG. Figure 3A 、 3Cand in the following detailed description. In some embodiments, the stretchable interconnects are configured to deform when a force is applied to the structured layer and / or a display having the structured layer, while the nodes are continuous areas of the structured layer and have limited ability to deform under the force. In some embodiments, the nodes are configured to deform. The nodes have at least one interconnect; preferably, at least three interconnects. The shape of the nodes and the location of the interconnect(s) can depend on the degree to which the display needs to stretch and the direction of the stretch. The nodes provide electrical and mechanical connections between the multiple interconnects. Having multiple interconnects on each node provides fault tolerance to interconnect failure. For example, if an interconnect fails, the nodes on either side of the failed interconnect that have connections to other interconnects will continue to be driven and supported by the remaining interconnects. Most likely, only the conductor (e.g., ITO) will break and the support material (e.g., PET) will still be connected and the electro-optical layer will still function. Because both ends of the interconnect will still be electrically connected to the node, which is still electrically connected to the rest of the display, the broken interconnect will continue to function. In other words, there will be no loss of active area.

[0050] Any suitable dimensions of the nodes and stretchable interconnects can be used. In some embodiments, the interconnects of the structured layer can be structured to provide uniform deformation as the structured layer is stretched. Both the nodes and the interconnect regions can have similar cross-sectional material composition, and the ability of the interconnects to deform is primarily based on the shape of the interconnects. The layer can be an electrode layer, an electrophoretic medium layer, and / or a substrate layer. The layer can initially be formed as a continuous layer, and can be structured to have nodes and stretchable interconnects by removing portions of the layer. Any suitable technique(s) for removing portions of a display layer can be used, such as laser cutting, using scissors, or using other cutting tools. When the structured layer that is structured to be a stretchable layer is an electro-optical medium layer, for example having one or more openings or patterns therein, an optional barrier layer or protective sheet or edge seal can be applied to the display to prevent moisture ingress and / or to prevent leakage of electro-optical material from the display. Examples of such seals are described in U.S. Patent No. 7,649,674.

[0051] An electro-optical display can be formed in operation 204 by attaching the multiple layers of the display together. An electro-optical display can be manufactured by laminating two electrodes (front and back electrodes) with an electro-optical layer in between. For example, the front electrode and the electro-optical layer can be attached to each other, constituting a front panel laminate, and can have a backing laminate adhesive with a release sheet attached. The release sheet can be removed and the front panel laminate can be attached to the back electrode. In some embodiments, a roll-to-roll process can be used, in which the front electrode and the electro-optical layer are rolled onto the back electrode. Examples of this type of processing are described in U.S. Patents Nos. 6,982,178 and 7,513,813. These techniques can be used to make displays such as Figure 1of the display 100. Alternative methods for preparing displays can be used. Techniques for constructing active matrix pixel displays can be used to form electro-optic displays having segmented electrodes as back electrodes.

[0052] The result of operation 204 is a stretchable electro-optic display. As previously described, the stretchable electro-optic display can include one or more layers (e.g., electrodes) that are structured (e.g., patterned) to exhibit stretchability even though formed of materials (multiple materials) that have relatively low intrinsic stretchability; and one or more layers (e.g., electro-optic medium layers) that exhibit relatively high stretchability.

[0053] One or more single layers of the stretchable display can be coupled to a drive circuit. According to aspects of the present application, the electrical connection areas on a single display can be coupled to a drive circuit using any suitable technique, such as by soldering, conductive glue, pin connections, and / or other types of electrical connections. Some embodiments can use rivet connections, which are formed by inserting a conductive connector through openings in both electrodes and the electro-optic layer of the display. In such embodiments, the connector can be positioned to mechanically and electrically contact one of the two electrodes. In some embodiments, a printed circuit board (PCB) that houses the drive circuit for one or more electro-optic displays in a composite display is coupled to the electrodes of the one or more displays. Thus, as previously described, control of individual electro-optic displays of a stretchable display can be provided.

[0054] The resulting stretchable display can conform to a shape having one or more compound curves. When the display conforms to the shape, stretchable interconnects connecting two nodes can stretch from an unstretched or relaxed state to a stretched state. The dimensions of the stretchable interconnects can determine the degree of stretch of the stretchable interconnects. The material properties of the layers having the stretchable interconnects can also determine the degree of stretch. In some embodiments, the dimensions of the interconnects can be configured to reduce strain at certain areas of the interconnects when the interconnects are elongated to the stretched state. The length of the stretchable interconnects can be elongated from the unstretched state to the stretched state, thereby increasing the distance between two nodes. In this manner, areas of the display can stretch from the unstretched state to conform to the shape. The display in the stretched state can cover a larger surface area than the display in the unstretched state. Similarly, when the display stretched to conform to the shape reverts to the unstretched state, the stretched areas of the display can contract to a less stretched state or a relaxed state. The interconnects are preferably 3 mm wide, but can be as small as 1 mm wide or as large as 10 mm wide or even wider, depending on the size and application of the stretchable display. The lower range of the width is limited by the cutting technology applied. For example, most laser cutting typically has a practical limit of 1 mm feature width. The upper range of the width is limited by the surface curvature of the portion to be stretched. Smaller curvature will require finer nodes and interconnects. The length of the interconnects will determine the degree to which the display can stretch.

[0055] It should be appreciated that the order of conforming the display and coupling the display to the drive circuit is not limited to coupling the display before conforming the display, and some embodiments include conforming the display to a shape having one or more compound curves before coupling the display to the drive circuit. Any suitable arrangement of nodes and stretchable interconnects can be employed to structure one or more layers to achieve the desired stretchable properties of the resulting display. Figure 3A An example arrangement of nodes 302a-302d and labeled interconnects 304a-304f and other unlabeled interconnects of a layer 300 of an electro-optic display is shown. A display having the layer 300 can stretch in one or more directions by extending at least a portion of the stretchable interconnects. The layer 300 can be an electrode layer, such as the electrodes 102 and 110, and / or a substrate layer. In some embodiments, the display can include multiple layers having similar structures of nodes and interconnects, such that openings exist in the display.

[0056] The active area of a display can be defined by the area of the display in which the structured electrode layer has a continuous portion of electrode material. For displays having a structured electrode layer, such as the display having the arrangement of layer 300, the configuration of the nodes and interconnects of the structured electrode layer can define the active surface area of the display, as the continuous portion of the electrode layer drives the electrophoretic medium. Since such an electrode layer is not continuous, the portions of the electrode layer in which there are nodes or interconnects can form active display area. Openings in the electrode layer, such as areas lacking electrode layer material, create inactive areas of the display, as there is no electrode layer to drive the electrophoretic material. The electrode layer can be patterned with nodes and interconnects to achieve a suitable active area of the display. In some embodiments, the configuration of the nodes and interconnects can provide sufficient active area of the display such that the inactive area is not noticeable to a viewer of the display. Preferably, the active area of the display will be at least 85% when un-stretched. More preferably, the active area of the display will be at least 95% when un-stretched. Most preferably, the display is 100% or nearly 100% active. In some applications, the amount of active area is less important, and an active area of about 85% or less is acceptable. The inactive area of the display can include any top plate connections as well as the width of the cut between the nodes and interconnects. Laser cutting is a preferred cutting method, which has a cut width of about 0.1 mm, which contributes to the inactive area of the display.

[0057] Figure 3B is a cross-sectional view of the display in FIG. 3 having an electrode layer 306 structured as layer 300 along line A-A'. The electrode layer 306 has continuous portions of electrode material as nodes 302d and 302c and portions forming stretchable interconnects 304c, 304e, and 304f. In this exemplary embodiment, the electrode layer 310 is continuous, as shown in Figure 3B The electrophoretic medium layer 308 is between the electrode layers 306 and 310. Since the display is controlled by applying a voltage across the electrophoretic medium layer 308, the Figure 3B active area of the display shown in FIG. 3 is where there is a portion of the electrode layer 306. While Figure 3B one structured electrode layer is shown having nodes and interconnects, other layers in the display can have similar structuring. In some embodiments, both electrodes 306 and 310 can be suitably structured to provide stretchability to the display. Such an implementation can be suitable when the materials used for both electrode layers have limited stretch properties. In some embodiments, the electrophoretic layer 308 and the electrode layers 306 and 310 can be structured to have nodes and stretchable interconnects, which is desirable for applications in which the display is both stretchable and allows moisture and air to pass through, such as in wearable display applications.

[0058] The nodes can be patterned within the layer 300 to have any suitable placement, spacing, and shape. For simplicity, Figure 3A Only four nodes are shown in the middle, but in practice, the display layer can have more (e.g., greater than 10 nodes, greater than 100 nodes, greater than 1,000 nodes, 10 to 500 nodes, or any number or range of numbers within such ranges). The nodes can be positioned uniformly, for example, in an array, but other arrangements are possible. In one embodiment, the nodes can be arranged on a backplane of an electro-optic display to provide an area on which precision active components, such as transistors and storage capacitors, can be positioned.

[0059] In Figure 3A In the middle, the nodes 302a-302d are arranged in a square and connected by interconnects 304a-304d, however, other arrangements of nodes and interconnects can be suitable depending on the desired properties of the resulting display. Although the nodes 302a-302d are shaped as squares, the nodes can have any suitable shape and / or size. The spacing between two nodes can be configured by the size of the interconnect connecting the two nodes. For example, the length LI of the interconnect 304a defines the distance between the nodes 302a and 302b, and the length L2 of the interconnect 304d defines the distance between the nodes 302a and 302d.

[0060] The interconnects can be patterned within the layer 300 to have any suitable placement and shape. Although Figure 3A One shape is shown in the middle, however, the interconnects can be structured to have any suitable shape, such as serpentine, coiled, zigzag, curved, or shaped in another way, such that the layer with the interconnects can expand and contract upon appropriate manipulation. The shape and / or size of the nodes and the stretchable interconnects can be selected based on the application of the resulting display. The extent to which the stretchable interconnects can extend can depend on the width of the interconnect material and the lateral dimension of the interconnect shape. As an example, Figure 3A The width w and lateral dimension d of the interconnect 304a are shown. For the interconnect, the width and / or dimension can vary to provide the interconnect with a desired amount of stretch. The lateral distance and width of a serpentine interconnect determine the amount of extension between nodes that will be achieved without damaging the electro-optic display. Generally, the longer the lateral distance, the greater the possible extension, as the deformation is spread over a longer path.

[0061] The size and shape of the interconnects can be selected based on the material properties of the layer 300 to reduce the amount of strain at points along the interconnects. In some embodiments, uniform deformation across the length of the interconnects can be achieved by varying the width and / or lateral dimension to reduce areas within the interconnects that can limit the interconnect elongation. In some embodiments, the electrode layer of the display can be configured to have nodes and interconnects to achieve an amount of effective surface area for the extent of the display. Generally, the stretchable portion of the display can move in more than one axis and can move along multiple planes.

[0062] The relative distance between the nodes can be varied by stretching one or more interconnects. Figure 3C is a stretched state of the layer 300 stretched along the x-direction. The interconnects 304a and 304c are elongated and have a greater length L3 along the x-direction in the stretched state Figure 3A than the less stretched or relaxed state of the layer 300 shown in Figure 3C with a length LI between the interconnects 304a and 304c. By stretching and extending the interconnect 304a in the x-direction, the distance between the nodes 302a and 302b is greater in the stretched state Figure 3C ) than in the unstretched state Figure 3A ). The structured layer can stretch non-uniformly such that some interconnects are elongated from the relaxed state and some interconnects remain in the relaxed state. In this manner, the stretched state of the layer or display having the structured layer can include one or more interconnects that have no or limited stretch, such as the interconnect 304d shown in Figure 3C Due to the limited stretch or no stretch along the y-direction in the stretched state depicted, the interconnect 304d has a length L4 that is similar to the length L2 when the layer 300 is in the relaxed state. Figure 3C

[0063] Figure 4 is another exemplary arrangement of nodes 402a-402e and stretchable interconnects (some labeled 404a-404d) of a layer 400 of a display. As shown in Figure 4 Node 402e is connected to a central portion of the interconnects 404a-404d. Such an arrangement can increase the amount of material remaining in the layer 400 and can be desirable for certain display applications. As an example, an electrode layer configured to have the arrangement of the layer 400 can produce a display having a desired amount of effective surface area, as the surface area of the electrode layer drives the electrophoretic medium in the display. The effective area of the display can be defined by the area of the display where the structured electrode layer has a continuous portion of electrode material.

[0064] Figure 5 ​is an exemplary arrangement of nodes connected to one another by stretchable interconnects to form a display layer. As shown, the dark black wavy lines represent cut lines that form the stretchable interconnects, while the light gray lines represent only the hexagonal nodes. Figure 5 As shown, the nodes are arranged in a pattern of hexagonal regions, with stretchable interconnects connecting adjacent nodes. Node 502a is connected to stretchable interconnects 504a-504f, which are arranged radially around node 502a. Stretchable interconnects 504c and 504f, which are connected to node 502a, are also connected to nodes adjacent to node 502a. For example, stretchable interconnect 504c is connected to both node 502a and node 502b, and stretchable interconnect 504f is connected to both node 502a and node 502c. In this way, the effective area of the display can be defined by the nodes and the stretchable interconnects connecting the nodes.

[0065] Figure 6A is an exemplary arrangement of interconnects connected to deformable nodes. As shown, the dark black lines represent cut lines and define nodes (squares) 602a, 602b, 602c, and 602d; the light gray lines also represent cut lines and define interconnects 604a, 604b, 604c, and 604d connected to node 602a of adjacent nodes.

[0066] Figure 6B is an enlarged version of Figure 6A . Nodes 602a, 602b, 602c, and 602d are adjacent nodes, and each node has four interconnects. Some of the interconnects are labeled 604a-604g. When the display is stretched, the interconnects (i.e., 604a-604g) remain fairly straight, and the nodes 602a-602d are distorted to stretch the display primarily along the Z-axis. Although the cut lines forming interconnects 604a-604g are shown as uniform parallel lines, the spacing between the cut lines and the relative lengths of the cut lines can vary depending on the desired stretchability and / or flexibility of the final display. For example, the light gray cut lines that are closer to the dark black cut lines can be closer together than the light gray cut lines that are relatively farther from the dark black cut lines. This would provide more effective area in the central region of the nodes than in the periphery of the nodes.

[0067] Having thus described several aspects of the technology of this application, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the technology described in the application. For example, those of ordinary skill in the art will readily devise various other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein without departing from the scope of the application. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that within the scope of the appended claims and equivalents thereto, embodiments of the application can be practiced otherwise than as specifically described. Furthermore, if any features, systems, articles, materials, kits, and / or methods are described as having been used, practiced, or disclosed with respect to a particular set of parameters, this is merely for convenience and clarity in description and illustration according to the patent statutes and does not constitute a limitation of the scope of the application or the claims. Any features, systems, articles, materials, kits, and / or methods that are described with respect to a particular set of parameters can be used, practiced, or disclosed with respect to any other set of parameters.

Claims

1. A flexible and stretchable electro-optical display comprising: a front electrode comprising a structured electrode layer having a plurality of cutouts such that the electrode layer of the front electrode is not continuous; a back electrode comprising a structured electrode layer having a plurality of cutouts such that the electrode layer of the back electrode is not continuous; an electrophoretic medium located between the front electrode and the rear electrode, comprising a suspending fluid and electrophoretic particles suspended in the suspending fluid; and The plurality of cutouts in the front electrode and the plurality of cutouts in the back electrode form a plurality of nodes with electrical connections, so that the flexible and stretchable electro-optical display can conform to a three-dimensional shape.

2. The flexible and stretchable electro-optical display of claim 1 , further comprising a voltage source coupled to the front electrode and the rear electrode and configured to provide a driving signal to the front electrode and the rear electrode, thereby generating an electric field that causes the electrophoretic particles to move in the suspension fluid.

3. The flexible and stretchable electro-optical display according to claim 1, wherein The plurality of cutouts form boundaries of the plurality of nodes and stretchable interconnects, and wherein the stretchable interconnects in the front electrode or the back electrode have a sinusoidal shape.

4. The flexible and stretchable electro-optical display according to claim 1, wherein The flexible and stretchable electro-optical display can conform to a shape having at least one compound curve.

5. The flexible and stretchable electro-optic display of claim 1, further comprising an elastomeric film attached to a surface of the flexible and stretchable electro-optic display and configured to provide mechanical support to the electro-optic display.

6. The flexible and stretchable electro-optical display according to claim 1, wherein the cutout of the front electrode or the cutout of the rear electrode is formed using a laser.

7. The flexible and stretchable electro-optical display of claim 6, wherein the interconnection area between the cutouts of the front electrode or the interconnection area between the cutouts of the back electrode is between 1 mm wide and 10 mm wide.

8. The flexible and stretchable electro-optic display of claim 1, wherein the thickness of the front electrode and the back electrode are each between 1 mil and 10 mils.

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