Electro-optical device including an identification mark

Abstract

An electro-optical device that sequentially includes a conductive light-transmissive layer, an electro-optic material layer, an adhesive layer, and a backplane substrate including a plurality of pixel electrodes, the plurality of pixel electrodes being configured to apply an electric potential between the conductive light-transmissive layer and the pixel electrodes. An activation region including an identification mark is located in a layer of the electro-optical device and emits radiation at a characteristic wavelength when stimulated to be activated, enabling the identification of the manufacturing source and manufacturing batch of the electro-optical device and its components. The technology is also related to a front-plane laminate and a double-release sheet, which are useful components in manufacturing the electro-optical device.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 891,486, filed Aug. 26, 2019, the entire contents of which are hereby incorporated by reference. Technical Field

[0003] The present invention relates to an electro-optic device that includes an activation region having an identification marker that emits radiation at a characteristic wavelength when stimulated to activate. The present invention enables verification of the manufacturing origin of the electro-optic device and its components and identification of the manufacturing lot of the electro-optic device and its components at any time during the useful life of the electro-optic device. Background Art

[0004] As used herein, the term "electro-optic" as applied to a material or device or display has its conventional meaning in the imaging art and refers to a material having first and second display states, at least one optical property of which is different, and which is changed from its first display state to its second display state by applying an electric field to the material. Although the optical property is usually a color perceptible to the human eye, it can be another optical property, such as light transmission, reflection, luminescence, or, in the case of a display for machine reading, a change in reflectivity at electromagnetic wavelengths outside the visible light range, i.e., a pseudo-color. Hereinafter, the terms "electro-optic device" and "electro-optic display" may be used interchangeably and considered synonyms.

[0005] The term "gray state" as used herein has its conventional meaning in the imaging art and refers to a state intermediate between two extreme optical states of a pixel and does not necessarily imply a black-and-white transition between these two extreme states. For example, several patents and published applications of E Ink Corporation described hereinafter describe such electrophoretic displays where the extreme states are white and dark blue, such that the intermediate "gray state" is actually light blue. In fact, as already mentioned, the change in optical state can not be a color change at all. Hereinafter, the terms "black" and "white" may be used to refer to the two extreme optical states of the 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. Hereinafter, the term "monochromatic" may be used to denote a driving scheme that drives the pixel only to its two extreme optical states without an intermediate gray state.

[0006] In the sense that the material has a solid outer surface, some electro-optic materials are solid, although the material may and often does have spaces filled with liquid or gas internally. For convenience, such displays using solid electro-optic materials may hereinafter be referred to as "solid electro-optic displays" or "solid electro-optic devices". Thus, the terms "solid electro-optic display" or "solid electro-optic device" include rotary bichromal member displays, encapsulated electrophoretic displays, microcell electrophoretic displays, and encapsulated liquid crystal displays.

[0007] The terms "bistable" and "bistability" are used herein in their conventional meaning in the art, referring to a display including a display element having first and second display states, at least one optical characteristic of the first and second display states being different, such that after driving any given element with an addressing pulse of a limited duration to present its first or second display state, after the termination of the addressing pulse, the state will persist for a time that is at least several times (e.g., at least 4 times) the minimum duration of the addressing pulse required to change the state of the display element. As shown in U.S. Patent No. 7,170,670, some particle-based electrophoretic displays that support grayscale can be stable not only in their extreme black and white states, but also in their intermediate gray states, and the same is true for some other types of electro-optic displays. This type of display is properly referred to as "multistable" rather than bistable, but for convenience, the term "bistable" may be used herein to cover both bistable and multistable displays.

[0008] Several types of electro-optic displays are known. One type of electro-optic display is the rotary bichromal member type, as described, for example, 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 a "rotary bichromal sphere" display, the term "rotary bichromal member" is preferably more precise because in some of the patents mentioned above, the rotary member is not spherical). Such displays use many small bodies (usually spherical or cylindrical) and internal dipoles, the bodies including two or more portions having different optical characteristics. These bodies are suspended within liquid-filled vesicles in a matrix, the vesicles being filled with liquid such that the bodies are free to rotate. The appearance of the display is changed by applying an electric field to the display, thereby rotating the bodies to various positions and changing which portion of the bodies is seen through the viewing surface. This type of electro-optic medium is typically bistable.

[0009] Another type of electro-optic display uses an electrochromic medium, such as an electrochromic medium in the form of a nanochromic thin film, the thin film including an electrode formed at least in part of a semiconducting metal oxide and a plurality of dye molecules attached to the electrode that are capable of reversibly changing color; see, e.g., 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. This type of nanochromic thin film is 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.

[0010] Another type of electro-optic display is the electrowetting display developed by Philips, which is described in Hayes, R.A. et al., "Video-Speed Electronic Paper Based on Electrowetting", Nature, 425, 383-385 (2003). Such an electrowetting display is shown in U.S. Patent No. 7,420,549 to be manufacturable as bistable.

[0011] One type of electro-optic display that has been the subject of intensive research and development for many years is the particle-based electrophoretic display, in which a plurality of charged particles move through a fluid under the influence of an electric field. When compared to liquid crystal displays, electrophoretic displays can have the attributes of good brightness and contrast, wide viewing angles, state bistability, and low power consumption. However, problems with the long-term image quality of these displays have hindered their widespread use. For example, the particles that make up electrophoretic displays tend to settle, resulting in insufficient service life for these displays.

[0012] As described above, an electrophoretic medium requires the presence of a fluid. In most prior art electrophoretic media, the fluid is a liquid, but an electrophoretic medium can be produced 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. Patent Nos. 7,321,459 and 7,236,291. When such gas-based electrophoretic media are used in a direction that allows particle sedimentation, such as in a sign where the medium is arranged in a vertical plane, this gas-based electrophoretic medium is prone to the same type of problems due to the same particle sedimentation as in liquid-based electrophoretic media. In fact, the problem of particle sedimentation in gas-based electrophoretic media is more severe than in liquid-based electrophoretic media because the lower viscosity of the gaseous suspension fluid allows electrophoretic particles to sediment faster compared to liquids.

[0013] Numerous patents and applications assigned to or in the names of the Massachusetts Institute of Technology (MIT), E Ink Corporation, E Ink California LLC, and related companies describe various techniques for encapsulated and microcell electrophoretic and other electro-optic media. Encapsulated electrophoretic media include a number of small capsules, each capsule itself including an inner phase and a capsule wall surrounding the inner phase, wherein the inner phase contains electrophoretically mobile particles in a fluid medium. Typically, these capsules themselves are held in a polymeric binder to form a coherent layer located between two electrodes. In a microcell electrophoretic display, the charged particles and fluid are not encapsulated within microcapsules, but are held within a number of cavities formed within a carrier medium (usually a polymeric film). The techniques described in these patents and applications include:

[0014] (a) electrophoretic particles, fluids, and fluid additives; see, for example, U.S. Patent Nos. 7,002,728 and 7,679,814;

[0015] (b) capsules, binders, and encapsulation processes; see, for example, U.S. Patent Nos. 6,922,276 and 7,411,719;

[0016] (c) microcell structures, wall materials, and methods of forming microcells; see, for example, U.S. Patent Nos. 7,072,095 and 9,279,906;

[0017] (d) Methods for filling and sealing microcells; see, for example, U.S. Patent Nos. 7,144,942 and 7,715,088;

[0018] (e) Thin films and subassemblies containing electro-optic materials; see, for example, U.S. Patent Nos. 6,982,178 and 7,839,564;

[0019] (f) Backplanes, adhesive layers, and other auxiliary layers and methods for use in displays; see, for example, U.S. Patent Nos. 7,116,318 and 7,535,624;

[0020] (g) Color formation and color adjustment; see, for example, U.S. Patent Nos. 7,075,502 and 7,839,564;

[0021] (h) Methods for driving displays; see, for example, U.S. Patent Nos. 7,012,600 and 7,453,445;

[0022] (i) Applications of displays; see, for example, U.S. Patent Nos. 7,312,784 and 8,009,348; and

[0023] (i) 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 encapsulation and microcell technologies other than displays; see, for example, U.S. Patent Application Publication Nos. 2015 / 0005720 and 2016 / 0012710.

[0024] Many of the foregoing patents and applications recognize that the walls surrounding discrete microcapsules in an encapsulated electrophoretic medium can be replaced by a continuous phase, thereby resulting in so-called polymer-dispersed electrophoretic displays, where the electrophoretic medium includes a plurality of discrete droplets of electrophoretic fluid and a continuous phase of polymer material, and the discrete droplets of electrophoretic fluid within such polymer-dispersed electrophoretic displays can be considered to be capsules or microcapsules even though no discrete capsule film is associated with each individual droplet; see, for example, U.S. Patent No. 6,866,760. Thus, for the purposes of this application, such polymer-dispersed electrophoretic media are considered to be a subclass of encapsulated electrophoretic media.

[0025] Although electrophoretic media are typically opaque (because, for example, in many electrophoretic media, the particles substantially block visible light from passing 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. Patent 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 changes in electric field strength, can operate in a similar mode; see U.S. Patent No. 4,418,346. Other types of electro-optic displays are also capable of operating in the shutter mode. Electro-optic media that operate in the shutter mode can be used in multi-layer structures for full-color displays; in such structures, at least one layer adjacent to the viewing surface of the display operates in the shutter mode to expose or hide a second layer that is further from the viewing surface.

[0026] Encapsulated electrophoretic displays are generally not subject to the aggregation and sedimentation failure modes of conventional electrophoretic devices and offer additional benefits, such as the ability to print or coat the display on a variety of flexible and rigid substrates. The use of the word "print" is intended to include all forms of printing and coating, including but not limited to: pre-metered coating such as patch die coating, slot or extrusion coating, slide or laminate coating, curtain coating; roll coating such as rod blade coating, forward and reverse roll coating; gravure coating; dip coating; spraying; meniscus coating; spin coating; brush coating; air knife coating; screen printing processes; electrostatic printing processes; thermal printing processes; inkjet printing processes; electrophoretic deposition (see U.S. Patent No. 7,339,715); and other similar techniques. Thus, the resulting display can be flexible. Additionally, because the display medium can be (using a variety of methods) printed, the display itself can be manufactured inexpensively.

[0027] Other types of electro-optic materials can also be used in the present invention. Of particular interest are ferroelectric liquid crystal displays (FLCs) that are known in the art to be bistable.

[0028] Other types of electro-optic media can also be used in the displays of the present invention.

[0029] An electro-optical device typically includes an electrophoretic material layer and at least two other layers disposed on opposite sides of the electrophoretic material, one of the two layers being an electrode layer. In most such devices, both layers are electrode layers, and one or both of the electrode layers are patterned to define the pixels of the display. For example, one electrode layer may be patterned as elongated row electrodes, while the other electrode layer may be patterned as elongated column electrodes extending at right angles to the row electrodes, and the pixels are defined by the intersections of the row and column electrodes. Alternatively, and more commonly, one electrode layer has the form of a single continuous electrode, while the other electrode layer is patterned as a matrix of pixel electrodes, each pixel electrode defining a pixel of the display. In another type of electrophoretic display intended to be used with a stylus, print head, or similar moveable electrode separate from the display, only one of the layers adjacent to the electrophoretic layer includes an electrode, and the layer on the opposite side of the electrophoretic layer is typically a protective layer intended to prevent damage to the electrophoretic layer by the moveable electrode.

[0030] The manufacture of a three-layer electrophoretic display typically involves at least one lamination operation. For example, in several patents and applications of the aforementioned MIT and E Ink, a process for manufacturing an encapsulated electrophoretic display is 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 (which serves as one electrode of the final display) on a plastic film, and the capsule / binder coating is dried to form a coherent layer of electrophoretic medium firmly adhered to the substrate. Separately, a backplane is prepared that includes an array of pixel electrodes and a suitable arrangement of conductors for connecting the pixel electrodes to a drive circuit. To form the final display, the substrate having the capsule / binder layer thereon is laminated to the backplane using a lamination adhesive. By replacing the backplane with a simple protective layer such as a plastic film (on which a stylus or other moveable electrode can slide), a very similar process can be used to prepare an electrophoretic display that can be used with a stylus or similar moveable electrode. In a preferred form of this process, the backplane itself is flexible and is prepared by printing the pixel electrodes and conductors on a plastic film or other flexible substrate. An obvious lamination technique for mass-producing displays by this process is roll lamination using a lamination adhesive.

[0031] The aforementioned U.S. Patent No. 6,982,178 describes a method of assembling a solid electro-optic display, including an encapsulated electrophoretic display, which is well-suited for mass production. Substantially, the patent describes a so-called "front plane laminate" ("FPL") that sequentially includes (a) a light-transmissive conductive layer; (b) a solid electro-optic layer; (c) an adhesive layer; and (d) a release film. Typically, the light-transmissive conductive layer will be carried on a light-transmissive substrate, which is preferably flexible in the sense that the substrate can be manually wrapped around (e.g.) a 10-inch (254 mm) diameter roller without permanent deformation. The term "light-transmissive" is used in this patent and herein means that the layer so designated transmits sufficient light for an observer to view changes in the display state of the electro-optic medium through the layer, which will generally be through the conductive layer and an adjacent substrate (if present); in the case where the electro-optic medium displays a change in reflectivity at an invisible wavelength, the term "light-transmissive" should of course be interpreted as relating to the transmission of the relevant invisible wavelength. The substrate is typically a polymer film and will generally have a thickness in the range of about 1 to about 25 mils (25 to 634 μm), preferably about 2 to about 10 mils (51 to 254 μm). The conductive layer is conveniently a thin metal or metal oxide layer such as aluminum or ITO, or can be a conductive polymer. Polyethylene terephthalate (PET) films coated with aluminum or ITO are commercially available, e.g., "aluminized Mylar" from DuPont Company of Wilmington, Delaware ("Mylar" is a registered trademark), and such commercial materials can have good results in the front plane laminate.

[0032] U.S. Patent No. 7,561,324 describes a so-called "double release sheet", which is essentially a simplified version of the front plane laminate of the aforementioned U.S. Patent No. 6,982,178. One form of the double release sheet includes a solid electro-optic medium layer sandwiched between two adhesive layers, where one or both of the adhesive layers are covered by a release film. Another form of the double release sheet includes a solid electro-optic medium layer sandwiched between two release films. Both forms of the double release sheet are intended for use in a process generally similar to the process of assembling an electro-optic display from a front plane laminate already described, but involving two separate laminations; typically, in the first lamination, the double release sheet is laminated to the front electrode to form a front subassembly, and then in the second lamination, the front subassembly is laminated to the backplane to form the final display, but the order of these two laminations can be reversed if desired.

[0033] U.S. Patent No. 7,839,564 describes a so-called "inverted front-plane laminate", which is a variant of the front-plane laminate described in the aforementioned U.S. Patent No. 6,982,178. The inverted front-plane laminate sequentially includes at least one of a light-transmissive protective layer and a light-transmissive conductive layer, an adhesive layer, a solid electro-optic dielectric layer, and a release film. The inverted front-plane laminate is used to form an electro-optic display, which has a laminated adhesive layer between the electro-optic layer and the front electrode or front substrate; a generally thinner second adhesive layer may or may not be present between the electro-optic layer and the backplane. Such an electro-optic display can combine good resolution with good low-temperature performance.

[0034] Light modulators represent a potentially important market for electro-optic dielectrics. As the energy performance of buildings and vehicles becomes increasingly important, electro-optic dielectrics can be used as coatings on windows (including skylights and awning tops) to electronically control the proportion of incident radiation passing through the window by changing the optical state of the electro-optic dielectric. Effective implementation of such "variable transmittance" ("VT") technology in buildings is expected to provide the following benefits: (1) reducing unwanted heat effects during hot weather, thereby reducing the energy required for cooling, the size of air-conditioning equipment, and peak electricity demand; (2) increasing the use of natural light, thereby reducing the energy used for lighting and peak electricity demand; and (3) increasing user comfort by increasing thermal and visual comfort. Even greater benefits are expected in automobiles, where the ratio of glass surface area to enclosed volume is significantly greater than in typical buildings. Specifically, effective implementation of VT technology in automobiles is expected not only to provide the above benefits but also to provide the following benefits: (1) improving driving safety, (2) reducing glare, (3) enhancing mirror performance (by using electro-optic coatings on mirrors), and (4) improving the ability to use head-up displays. Other potential applications of VT technology include privacy glass and glare protection in electronic devices.

[0035] The term "impulse" is used herein in its conventional meaning, i.e., the integral of voltage with respect to time. However, some bistable electro-optic dielectrics are used as charge converters, and for such dielectrics, an alternative definition of impulse can be used, i.e., the integral of current with respect to time (which is equal to the total charge applied). The appropriate definition of impulse should be used depending on whether the dielectric is used as a voltage-time impulse converter or as a charge impulse converter.

[0036] Another complication in driving an electrophoretic display is the need for so-called "DC balance". As discussed in U.S. Patent Nos. 6,531,997 and 6,504,524, problems may be encountered, and if the method used to drive the display does not result in a net time-averaged applied electric field across the electro-optic medium that is zero or close to zero, the operating life of the display is shortened. A driving method that does result in a zero net time-averaged applied electric field across the electro-optic medium is conveniently referred to as "DC balance" or "direct current balance".

[0037] As already noted, an encapsulated electrophoretic medium typically includes electrophoretic capsules disposed in a polymeric binder, which serves to form discrete capsules into a coherent layer. The continuous phase in a polymer-dispersed electrophoretic medium and the cell walls of a microcellular medium serve a similar function. E Ink researchers have found that the particular material used as a binder in an electrophoretic medium affects the electro-optic properties of the medium. Among the electro-optic properties of an electrophoretic medium that are affected by binder selection is what is referred to as "dwell time dependence", as discussed in U.S. Patent No. 7,119,772 (see especially FIGS. 34 and the associated description). It has been found that at least in some cases, the impulse required for a transition between two particular optical states of a bistable electrophoretic display varies with the dwell time of the pixel in its initial optical state, a phenomenon referred to as "dwell time dependence" or "DTD". Clearly, it is desirable to make DTD as small as possible, since DTD affects the difficulty of driving the display and may affect the quality of the image produced; for example, DTD may cause the gray levels of pixels that should form a uniform gray area to vary slightly from one another, and the human eye is very sensitive to such variations. Although it has been known that binder selection affects DTD, hitherto, the selection of an appropriate binder for any particular electrophoretic medium has been based on trial and error, with little understanding of the relationship between DTD and the chemical properties of the binder.

[0038] U.S. Patent Application Publication No. 2005 / 0107564 describes an aqueous polyurethane dispersion comprising a polyurethane polymer, which polyurethane polymer comprises the reaction product of: (a) a terminal isocyanate prepolymer, which prepolymer comprises the reaction product of: (i) at least one polyisocyanate comprising α,α,α,α-tetramethylxylene diisocyanate [chemical name 1,3-bis(1-isocyanato-1-methylethyl)benzene; this material will hereinafter be referred to as "TMXDI"]; (ii) at least one difunctional polyol comprising polypropylene glycol, and (iii) an isocyanate-reactive compound comprising an acidic functional group and at least two isocyanate-reactive groups selected from the group consisting of hydroxyl, primary amino, secondary amino, and combinations thereof; (b) a neutralizing agent comprising a tertiary amino group; (c) a monofunctional chain terminator; (d) a chain extender comprising an organic diamine; and (e) water. It has been found that such a polyurethane dispersion (which may hereinafter be referred to as a "TMXDI / PPO" dispersion) can be used as a lamination adhesive in an electro-optical display.

[0039] The following discussion focuses on methods for driving one or more pixels of an electro-optical display through a transition from an initial gray level to a final gray level (which may be different from or the same as the initial gray level). The term "waveform" will be used to denote the entire voltage-versus-time curve for effecting a transition from a particular initial gray level to a particular final gray level. Typically, such a waveform will comprise a plurality of waveform elements, where the elements are substantially rectangular (i.e., where a given element comprises the application of a constant voltage over a period of time); the elements may be referred to as "pulses" or "drive pulses". The term "driving scheme" denotes a set of waveforms sufficient to effect all possible transitions between the gray levels of a particular display. A display may utilize more than one driving scheme; for example, the aforementioned U.S. Patent No. 7,012,600 teaches that the driving scheme may need to be modified according to parameters such as the temperature of the display or the time that it has been operated during its lifetime, and thus the display may be provided with a plurality of different driving schemes for use at different temperatures, etc. A set of driving schemes used in this manner may be referred to as "a set of related driving schemes". As described in the aforementioned "Methods for driving displays" application, more than one driving scheme may also be used simultaneously in different regions of the same display, and a set of driving schemes used in this manner may be referred to as "a set of simultaneous driving schemes".

[0040] A need in the field of electronic devices is to identify the manufacturing source and lot of such devices and their components in order to troubleshoot and resolve quality issues at any time during the useful life of the device. The present invention seeks to provide suitable tools to meet this need in an efficient and effective manner. SUMMARY OF THE INVENTION

[0041] Accordingly, in one aspect, the present invention provides an electro-optic device comprising, in sequence, (a) a conductive light-transmissive layer, (b) an electro-optic material layer, (c) an adhesive layer, and (d) a backplane substrate including a plurality of pixel electrodes configured to apply an electric potential between the conductive light-transmissive layer and the pixel electrodes, wherein the electro-optic device includes an activation region having an identification mark that emits radiation having a characteristic wavelength profile when stimulated to activate, and wherein the activation region is located within one of the layers of the electro-optic device or adjacent to one of the layers of the electro-optic device.

[0042] In another aspect, the present invention provides a front-plane laminate comprising, in sequence, (a) a conductive light-transmissive layer, (b) an electro-optic material layer, (c) an adhesive layer, and (d) a release film, wherein the front-plane laminate includes an activation region having an identification mark that emits radiation having a characteristic wavelength profile when stimulated to activate, wherein the activation region is located within one of the layers of the front-plane laminate or adjacent to one of the layers of the front-plane laminate.

[0043] In another aspect, the present invention provides a dual-release sheet for manufacturing an electro-optic device comprising, in sequence, (a) a first release film, (b) a first adhesive layer, (c) an electro-optic material layer, (d) an adhesive layer and a second release film, wherein the dual-release sheet includes an activation region having an identification mark that emits radiation having a characteristic wavelength profile when stimulated to activate, and wherein the activation region is located within one of the layers of the dual-release sheet or adjacent to one of the layers of the dual-release sheet.

[0044] In another aspect, the present invention provides a method of verifying an electro-optic device and any of its components, comprising the steps of (a) providing an electro-optic device comprising, in sequence, a conductive light-transmissive layer, an electro-optic material layer, an adhesive layer and a backplane substrate including a plurality of pixel electrodes configured to apply an electric potential between the conductive light-transmissive layer and the pixel electrodes, wherein the electro-optic device includes an activation region having an identification mark that emits radiation having a characteristic wavelength profile when activated, and wherein the activation region is located within one of the layers of the electro-optic device or adjacent to one of the layers of the electro-optic device, (b) stimulating the activation of the identification mark, (c) detecting the emitted electromagnetic radiation caused by the identification mark, and (d) determining the authenticity of the device or any of its components or determining the manufacturing lot of the electro-optic device or any of its components. Description of the Drawings

[0045] Of the drawings Figure 1A And 1B Are illustrations of examples of electro-optic devices having identification marks in the adhesive layer. Examples of the steps of the process for manufacturing such devices from front-plane laminates are described graphically.

[0046] Of the drawings Figures 2A to 2EIllustration of another example of an electro - optical device having an identification mark in an adhesive layer. An example of the steps of a process for manufacturing such a device from a double - release adhesive sheet is graphically described.

[0047] Figure 3A 、 3B And 3C are illustrations of an electro - optical device having an activation region that is a coating on a backplane substrate. Examples of different steps of a process for manufacturing such a device from a front - plane laminate are graphically described.

[0048] Figure 4 Illustration of an electro - optical device having an electrophoretic medium. The electrophoretic medium includes charged particles as an identification mark.

[0049] Figure 5 Illustration of an electro - optical device having a micro - encapsulated electrophoretic medium. The shell of the microcapsules includes particles as an identification mark.

[0050] Figure 6A 、 6B 、6C and 6D are photographs of an electro - optical device having an activation region that is a coating on a backplane substrate, where the electro - optical device is illuminated by (1) a typical fluorescent lamp and (2) blue light.

[0051] Figure 7 Illustration of the interaction of incident light with an electro - optical device. The activation region of the electro - optical device is a coating on the side of the backplane substrate facing the adhesive layer. Detailed Description

[0052] The present invention provides an electro - optical device that includes an activation region having an identification mark in one of its layers, enabling the identification of the manufacturing source of the device and its components. The technology also enables the identification of the manufacturing lot of the electro - optical device and its components at any time during the service life of the device.

[0053] The electro - optical device of the present invention sequentially includes a conductive light - transmissive layer, an electro - optical material layer, an adhesive layer, and a backplane substrate. The backplane substrate includes a plurality of pixel electrodes configured to apply an electric potential between the conductive light - transmissive layer and the pixel electrodes. The electro - optical device includes an activation region having an identification mark that emits radiation with a characteristic wavelength profile when stimulated to activate, and wherein the activation region is located in one of the layers of the electro - optical device.

[0054] Common methods of manufacturing electro-optic devices involve using a front planar laminate (FPL) which sequentially includes a conductive light-transmissive layer, an electro-optic material layer, an adhesive layer, and a release film. The FPL can be produced and stored at one location or shipped to another location. It can be used to manufacture the corresponding electro-optic device at the desired time and location. The release film can be simply removed, exposing the adhesive layer and enabling the manufacturer to simply attach a backplane substrate to obtain the electro-optic device. Incorporating an activation region with an identification mark in one of the layers of the FPL enables verification of the manufacturing origin of the FPL and identification of the manufacturing lot of the FPL at any time during the service life of the FPL and the resulting electro-optic device.

[0055] Another method of manufacturing electro-optic devices involves using a dual-release sheet which sequentially includes a first release film, a first adhesive layer, an electro-optic material layer, an adhesive layer; and a second release film. The dual-release film can be produced and stored at one location or shipped to another location. It can be used to manufacture the corresponding electro-optic device at the desired time and location. The first release film can be removed, exposing the first adhesive layer, and enabling the manufacturer to attach the conductive light-transmissive layer. Then, the second release film can be removed, exposing the second adhesive layer, and enabling the manufacturer to simply attach the backplane substrate to the second adhesive layer to obtain the electro-optic device. Incorporating an activation region with an identification mark in one of the layers of the dual-release sheet enables verification of the manufacturing origin of the dual-release sheet and identification of the manufacturing lot of the dual-release sheet at any time during the service life of the dual-release sheet and the resulting electro-optic device.

[0056] As used herein, the term "light" is electromagnetic radiation of any wavelength, not just electromagnetic radiation in the visible spectrum.

[0057] Desirable activation regions and corresponding identification marks have the following characteristics:

[0058] a. It should be capable of being easily detected by visual inspection or by using analytical instruments;

[0059] b. It should not significantly interfere with the operation or appearance of the electro-optic device.

[0060] The identification mark can be a fluorescent dye, a fluorescent pigment, a phosphorescent dye, a phosphorescent pigment, or a mixture thereof.

[0061] The identification mark can include a fluorescent dye or a combination of two or more fluorescent dyes. The identification mark can also include a fluorescent pigment or a combination of fluorescent pigments. The identification mark can also include a combination of a fluorescent dye and a fluorescent pigment. A fluorescent dye or a fluorescent pigment is a compound that absorbs light and re-emits light at a different wavelength. Generally, the emission wavelength is longer than the wavelength of the incident light.

[0062] A dye is a material that is soluble in the medium of the composition in which it is used. In contrast, a pigment is a material that is insoluble in the medium of the composition in which it is used and exists in solid form.

[0063] The identification marker can include a phosphorescent dye or a combination of two or more phosphorescent dyes. The identification marker can also include a phosphorescent pigment or a combination of phosphorescent pigments. The identification marker can also include a combination of a phosphorescent dye and a phosphorescent pigment. A phosphorescent dye or pigment is a compound that absorbs light and re-emits light at a different wavelength, where the emission occurs over a period of time that is typically longer than in the case of fluorescence after exposure to light.

[0064] Fluorescent and phosphorescent dyes and pigments, which can be collectively referred to as luminescent dyes and pigments, can be members of the acridine, cyanine, fluorescein, fluorescein, oxazine, phenanthridine, and rhodamine chemical classes. Non-limiting examples of luminescent dyes and pigments are acridine orange, acridine yellow, acriflavine, GelGreen, Cy2, Cy3, Cy3.5, Cy5, Cy5.5, Cy7, Cy7.5, DiI, DiOC6, heptamethine dyes, indocyanine green, merocyanine, SYBR Green I, SYBR Safe, Sytox, YOYO-1, calcein, carboxyfluorescein diacetate N-succinimidyl ester, carboxyfluorescein N-succinimidyl ester, dichlorofluorescein, 6-carboxyfluorescein, eosin Y, eosin B, erythrosine, fluo-3, fluo-4, fluorescein, fluorescein amidite, fluorescein isothiocyanate, Indian yellow, mercurochrome, Pacific blue, phloxine B, seminaphtharhodafluor, coelenterazine, firefly luciferin, ostracod luciferin, brilliant cresyl blue, cresyl violet, gallocyanine, Nile blue, Nile red, resazurin, ethidium bromide, GelRed, propidium iodide, rhodamine 6G, rhodamine B, rhodamine 123, sulforhodamine 101, Texas red, and sulforhodamine B.

[0065] The activation region can be located in the adhesive layer or the FPL of the electro-optical device, or it can be located in a position adjacent to the adhesive layer. In the case of a double-release sheet, the activation region can be located in any adhesive layer or it can be located in a position adjacent to one or both adhesive layers. For example, the identification marker of the activation region can be part of a coating that contacts the adhesive layer. The activation region can form an image that includes letters, numbers, or a combination thereof.

[0066] In a variant of the present invention, the activation region is in the adhesive layer. More specifically, before applying the adhesive material onto the electro-optical material layer to create the adhesive layer, the identification marker can be combined with the adhesive material. Figure 1A and 1BIllustrations of FPLs and electro - optical devices having identification marks in the adhesive layer are provided. Figure 1A and 1B Examples of different steps of a process for manufacturing FPLs and electro - optical devices having identification marks in the adhesive layer are also provided. More specifically, Figure 1A is an example of a process for manufacturing an FPL. The identification mark is mixed with the adhesive material to form a combination of the adhesive material and the identification mark. This combination is denoted by 103. Then, the combination 103 of the adhesive material and the identification mark is coated on the film 105 to form an adhesive film 105A. Then the adhesive film is applied to a manufactured article that includes a conductive light - transmissive layer 101 and an electro - optical material layer 102. Thus, an adhesive layer 104A is formed on the electro - optical material layer 102, which is in contact with the film 105 used as a release layer. The resulting FPL 106A includes an identification mark that can verify the manufacturing source of the FPL and the resulting electro - optical device and identify its manufacturing batch.

[0067] A front - plane laminate (FPL) is an article that can be used immediately for manufacturing an electro - optical device, or it can be stored, transported, and later used for manufacturing an electro - optical device, as Figure 1B shown. More specifically, the release film can be removed from the FPL 106A and the FPL can be attached to the surface of a back - plane substrate 107 to complete the manufacturing process of the electro - optical device 108A. The back - plane substrate includes a plurality of pixel electrodes and a driving means arranged to apply a variable potential to the pixel electrodes.

[0068] The resulting electro - optical device 108A includes an identification mark that can verify the manufacturing source of the electro - optical device and identify its manufacturing batch.

[0069] In another variant of the present invention, the activation region of the double - release sheet is located in the adhesive layer of the double - release sheet (and the resulting electro - optical device). Figures 2A to 2E Examples of a process for manufacturing an electro - optical device according to the present invention are provided. The inventive device containing the activation region is denoted as 290 in Figure 2E An example of a double - release sheet containing an activation region in the adhesive layer is denoted as 260 in Figure 2C Examples of steps of a process for manufacturing a double - release sheet according to the present invention are provided in Figure 2A , 2B and 2C. The identification mark can be combined with the adhesive material before being applied to the first release film 221. The combination of the adhesive material and the identification mark forms a first adhesive composition 222. The first adhesive composition 252 is applied to the first release film 221 to form a first adhesive layer 223 on the first release film 221. Subsequently, a third release film 224 is placed on the first adhesive layer 223 to form a first release roll 220. In Figure 2BIn the separate steps shown, an electro-optic material composition is coated on a fourth release film 231 to form a structure 230. After peeling the third release film 224 from the first release roller 220 and bringing the exposed first adhesive layer 223 into contact with the electro-optic material layer 232 of the structure 230, an intermediate electro-optic web 240 is formed. The intermediate electro-optic web 240 can be used to form a dual-release sheet 260, as Figure 2C shown. A second adhesive composition 252 is applied to a second release film 251 to form a second adhesive layer 253, which is part of a second release roller 250. The second adhesive composition 252 can be made by mixing an identification mark with the adhesive material. After peeling the fourth release film 231 from the intermediate electro-optic web 240 and bringing the exposed surface of the electro-optic material layer 232 into contact with the second adhesive layer 253 of the second release roller 250, a dual-release sheet 260 is formed. The identification mark can be included in one of the adhesive layers 223 or 253. The identification mark can be included in both the first adhesive layer 223 and the second adhesive layer 253. In the latter case, the first adhesive layer 223 can include an identification mark or a combination of different identification marks that is different from the identification mark (or combination of identification marks) included in the second adhesive layer 253 of the dual-release sheet.

[0070] A dual-release sheet 260 that includes one or more identification marks in one or both of its adhesive layers can be stored and later used in the production of electro-optic devices. Figure 2D and 2E shows an example of the steps of a process for manufacturing an electro-optic device using a dual-release sheet. The second release film 251 of the dual-release sheet 260 is removed, and a backplane substrate 270 is attached to the exposed surface of the second adhesive layer 253 to form a structure 275. Then, the first release film 221 is removed from the structure 275 and the exposed first adhesive layer 223 is attached to a transparent conductive electrode 280 to form an electro-optic device 290 that includes a transparent conductive electrode layer 281. Attaching the transparent conductive electrode 280 to the dual-release sheet can be performed before attaching the backplane substrate 270. The resulting electro-optic device 290 includes at least one identification mark (or combination of identification marks) in at least one of its adhesive layers, as in the form of the dual-release sheet from which it is made. The identification mark or combination of identification marks enables verification of the manufacturing source of the electro-optic device and identification of the manufacturing lot of the electro-optic device.

[0071] Verification of the origin of manufacture and / or identification of the manufacturing batch of an electro-optical device can be carried out by irradiating the surface of the backplane substrate with light (stimulus), which causes the identification mark to emit radiation with a characteristic wavelength profile that is visible or measurable from the outer surface of the backplane substrate. Thus, visual inspection or spectrometry of the radiation with the characteristic wavelength profile emitted from the backplane substrate can determine the authenticity (or inauthenticity) of the electro-optical device. Although pixel electrodes are present therein, the backplane substrate is generally (or it can be designed to) at least partially transmit ultraviolet, visible, and near-infrared radiation, making the process of verifying the origin of manufacture and / or identifying the manufacturing batch of the electro-optical device feasible. Even in the case where the backplane substrate is opaque (with respect to the regions of the electromagnetic spectrum mentioned above), verification of the origin of manufacture and / or identification of the manufacturing batch can be achieved by separating the backplane substrate from the remainder of the device, verifying the origin of manufacture of the device and / or identifying the manufacturing batch of the device when necessary, and reconnecting the backplane substrate to the remainder of the device. Alternatively, verification and / or identification can be achieved by using identification marks that do not rely on ultraviolet, visible, or near-infrared radiation. Identification marks that provide a characteristic response to higher energy radiation (such as x-rays or gamma rays) can be used.

[0072] In a variant of the invention, the activation region is adjacent to the adhesive layer. More specifically, the activation region can be a coating on a layer of the electro-optical device that is in contact with the adhesive layer. The activation region can be (a) a coating on the electro-optic material layer, (b) a coating on a thin film forming the release layer (created before applying the adhesive composition on the thin film), or (c) a coating on the backplane substrate. In the case of FPL, the activation region can be (a) a coating on the electro-optic material layer, (b) a coating on the adhesive layer, created before attaching the first release film, or (c) a coating on the release film. In the case of a double release sheet, the activation region can be (a) a coating on the backplane substrate, (b) a coating on the first adhesive layer, created before attaching the first release film, (c) a coating on the first release film, (d) a coating on the second adhesive layer, created before attaching the second release film, (e) a coating on the first release film, or (f) a coating on the second release film.

[0073] The identification mark itself or a solution or dispersion of the identification mark can be used for the coating. The coating can also contain a film-forming polymer. Figure 3A and 3B Illustrations of FPL and electro-optical devices using FPL are provided. The activation region is a coating on the backplane substrate. Figure 3AThis is an example of a process for manufacturing an FPL. An adhesive material 109 is applied onto a film 105 to create an adhesive film 105B. Then the adhesive film is applied onto an electro-optic material layer 102. The electro-optic material layer is in contact with a conductive and light-transmissive layer 101. An FPL 106B is formed using this process. This is an article that can be immediately used for manufacturing an electro-optic device, or it can be stored, transported, and later used for manufacturing an electro-optic device, such as Figure 3B shown. More specifically, the release film can be removed from the FPL 106B and the FPL can be attached to a backplane substrate 107 to complete the manufacturing process of the electro-optic device 108B. In this example, the backplane substrate has been pre-coated with a composition 103 containing an identification mark. The activation area, i.e., the coating 110, can be performed using any coating technique, such as pre-metered coating such as patch die coating, slot or extrusion coating, slide or laminate coating, curtain coating; roller coating such as roll knife coating, forward and reverse roll coating; imprinting; concave coating; aniline printing; dip coating; spraying; meniscus coating; spin coating; brush coating; air knife coating; screen printing process; electrophotographic printing process; thermal printing process; inkjet printing process; and other similar techniques.

[0074] Figure 3C An illustration of the electro-optic device 108B as viewed from the upper surface of the electro-optic device from the side where the conductive and light-transmissive layer is located is provided. The activation area 110 is on the backplane substrate and is in contact with the adhesive layer 104. The activation area forms an image including the letters (“EPD”).

[0075] There are multiple scenarios regarding how this method can be used for the verification of the manufacturing origin and the identification of manufacturing batches of FPLs, double-release sheets, and electro-optic devices. As described above, before forming the adhesive layer of the FPL or the double-release sheet, an identification mark (such as a fluorescent dye or pigment) that provides emission (upon stimulation activation) with a characteristic wavelength profile can be mixed into the adhesive material. The emission can be visually observed or spectroscopically determined. Multiple fluorescent and / or phosphorescent dyes in different ratios can be used such that the emission profile is more complex and capable of encoding additional information that can be detected during the service life of the FPL, double-release sheet, or electro-optic device. That is, the wavelength peak and the light amplitude at the peak depending on the nature of the dye and the quantity ratio of the dyes can encode multiple information, such as the manufacturing location, manufacturing time, manufacturing batch, material source, etc.

[0076] The identification markings can also be coated on one or more of the surfaces of the FPL, double release sheet, or multiple layers of the electro-optic device. As described above, the coating provides additional flexibility by allowing the creation of multiple images that can be detected upon activation. These images can include numbers and letters that can correspond to the manufacturing lot and other specific information of the FPL, double release sheet, or electro-optic device. In the case of the FPL and the corresponding electro-optic device, the activation area can be the result of (a) a coating on the electro-optic material layer before attaching the adhesive layer, (b) a coating on the surface of the film forming the release layer before coating the adhesive composition on the film, or (c) a coating on the backplane substrate before attaching the adhesive layer of the FPL. In option (b), after removing the release film, the activation area remains at least partially on the surface of the adhesive layer. Additionally, multiple identification markings, such as fluorescent dyes, can be included at different locations on the same FPL and electro-optic device, making the emitted light more complex and capable of encoding more information for the electro-optic device, FPL, and its components. In the case of the double release sheet and the corresponding electro-optic device, the activation area can be (a) a coating on the backplane substrate, (b) a coating on the first adhesive layer created before attaching the first release film, (c) a coating on the first release film, (d) a coating on the second adhesive layer created before attaching the second release film, (e) a coating on the first release film, or (f) a coating on the second release film.

[0077] Multiple stimuli can be used to activate the identification markings, such as (a) electromagnetic radiation in the visible and near-infrared regions of the electromagnetic spectrum, having a wavelength of about 400 nm to about 1000 nm, (b) electromagnetic radiation in the ultraviolet region of the electromagnetic spectrum, having a wavelength of about 200 nm to about 400 nm, (c) electromagnetic radiation in the x-ray region of the electromagnetic spectrum, having a wavelength of about 0.01 nm to about 10 nm, and (d) in the gamma-ray region of the electromagnetic spectrum, having about 10 -2 to about 10 -6Electromagnetic radiation with a wavelength of nm. This electromagnetic radiation must penetrate the FPL, the double-release sheet, or the electro-optical device and reach the identification marker to cause a response in the form of characteristic emission. The emitted radiation from the identification marker must also penetrate out of the FPL, the double-release sheet, and the electro-optical device so that it can be detected from the outside of the FPL, the double-release sheet, or the electro-optical device. In this case, it is required that the layers of the FPL, the double-release sheet, or the electro-optical device transmit at least partially near-infrared, visible, or ultraviolet radiation. Identification markers that can be activated by electromagnetic radiation and emit characteristic wavelength profiles with longer wavelengths (lower energies) are used, enabling the verification of the manufacturing origin and the identification of the manufacturing batches of FPLs, double-release sheets, and devices that are opaque to near-infrared, visible, or ultraviolet radiation. Lanthanide elements of the periodic table, such as europium, gadolinium, terbium, and their salts, can be used as identification markers. They can be activated by x-rays and gamma rays. X-rays and gamma rays easily penetrate the materials used in electro-optical devices. The penetration of this high-energy electromagnetic radiation can only be blocked by thick metal layers of heavy metals (such as lead). After activation by x-rays and gamma rays, the lanthanide metals and their salts emit characteristic spectra that can be detected via x-ray fluorescence (XRF). The detection limit of XRF is very low (in the ppm range), which means that very small amounts of lanthanide metals or their salts are sufficient to enable the verification of FPLs, double-release sheets, or electro-optical devices. The lanthanide metals or their salts can be present in any layer of the FPL, the double-release sheet, or the electro-optical device, such as the adhesive layer or the electro-optical material layer, or it can be part of a coating on any layer. In addition to the above elements (europium, gadolinium, terbium), the lanthanides include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0078] In another variant of the present invention, the identification marker can be present in the FPL, the double-release sheet, and the electro-optical device in the form of particles located in the electro-optical material layer. These particles can be charged or uncharged.

[0079] As described above, in certain types of electro-optical devices (or FPLs, or double-release sheets), the electro-optical material layer includes an electrophoretic medium that has a plurality of first charged particles that move through a fluid under the influence of an electric field, resulting in different display states that are different in at least one optical property. The electrophoretic medium can be encapsulated by a plurality of microcapsules having microcapsule shells. Generally, such electro-optical devices include a plurality of at least one charged particle, but they can include a plurality of particles that contribute to multiple potential optical states. The encapsulated electrophoretic medium can also include a plurality of second charged or uncharged particles, where the second particles can be the identification marker. The second particles can be distinguished from the first particles and any other particles present in the electrophoretic medium via visual inspection, microscopy, or spectrometry of the electro-optical device (or FPL, or double-release sheet). Instead of the electrophoretic medium in the form of microcapsules, it can be present in a plurality of micro-units formed using a polymer material, as described above.

[0080] The electro-optic material of an electro-optic device (or FPL, or double-release sheet) may include an electrophoretic medium that includes a plurality of first and second charged particles that move through a fluid under the influence of an electric field, resulting in different display states that differ in at least one optical property. The electrophoretic medium may be encapsulated by a plurality of microcapsules having microcapsule shells. The encapsulated electrophoretic medium may further include a plurality of third pigment particles that are part of the microcapsule shells, and the third particles may be identification markers. The third particles can be distinguished from the first particles, the second charged particles, and any other particles in the electrophoretic medium via visual inspection, microscopy, or spectroscopy of the electro-optic device (or FPL, or double-release sheet).

[0081] Typical methods for manufacturing the encapsulated electrophoretic medium include the following steps: (a) mixing an aqueous mixture of gelatin and gum arabic polymers in a hydrocarbon solvent in the presence of emulsified droplets containing charged particles; (b) heating the mixture to about 40 °C and lowering the pH value to about 4.9, thereby forming microcapsules having a shell containing a gelatin / gum arabic coacervate layer; (c) lowering the temperature of the mixture to about 10 °C; (e) adding an aqueous solution of glutaraldehyde to crosslink the microcapsule shells; (f) vigorously mixing the mixture at about 25 °C for more than 12 hours; (g) raising the temperature to 50 °C and mixing for another 1 hour to remove excess crosslinking agent; (g) separating out capsules larger than 100 μm by sieving. The retained microcapsules are mixed with a polymeric binder and coated on the electro-optic electrodes to form an electro-optic material layer.

[0082] As described above, the presence of a small content of additional types of charged particles in the total content of charged particles in the electrophoretic medium enables the corresponding electro-optical device to be verified. In other words, the additional types of charged particles can be used as identification markers in the corresponding FPL, dual-release sheet, and electro-optical device. To be effectively used as an identification marker, the type of charged particle must be detectable via visual inspection of the electro-optical device (or FPL, or dual-release sheet) or by measurement using an analytical instrument (such as an optical microscope). Spectral measurements carried out by various techniques (such as UV-Vis spectroscopy, infrared spectroscopy, X-ray fluorescence, etc.) can also be used. Thus, preferably, the charged particle identification marker has at least one different property compared to other types of charged particles in the electro-optical material layer. They can have a different color, different shape, or different size compared to other types of charged particles. Alternatively, the charged particle identification marker can be a fluorescent or phosphorescent pigment, which can be detected by the emission of electromagnetic radiation with a characteristic wavelength profile when excited by electromagnetic radiation of a specific wavelength. To avoid the identification marker significantly interfering with the operation of the electro-optical device and its optical state, preferably, the content of the charged particle identification marker is relatively low compared to the total weight content of the charged particles present in the electro-optical material layer. Thus, the charged particle identification marker can be from about 0.01 wt% to about 2 wt%, more preferably from about 0.02 wt% to about 0.5 wt%, and even more preferably from about 0.05 wt% to about 0.2 wt% of the weight of the total charged particle content of the electro-optical material layer. Certain protocols for applying an electric field can be utilized to enable the verification of the device based on the charged particle identification marker. For typical visual inspection or optical microscope measurement, the charged particles must be visible from the surface of the electro-optical material layer.

[0083] Figure 4 A diagram is provided showing an example where the identification marker is positively charged particles 116 in an encapsulated electrophoretic medium 114. In this example, the electrophoretic medium of the electro-optical layer 102 also includes positively charged black pigment particles 115A and negatively charged white particles 114B. An electric field is applied across the electrodes of the device, with a negative charge on the conductive transparent electrode 101, such that the positively charged particles 115A and 116 move closer to the viewing side of the electro-optical device and the negatively charged white particles move towards the opposite side of the electro-optical layer. This enables visual inspection or spectral measurement of the charged particle identification marker, thereby verifying the electro-optical material layer and the corresponding electro-optical device. Those skilled in the art will understand that the identification marker can also be negatively charged particles.

[0084] The presence of a small content of additional types of uncharged particles in the total content of charged particles in the electrophoretic medium can also enable verification of the corresponding electro-optical devices (FPL and dual-release sheets). It has been observed that even if the particles do not carry a charge, the particles can be driven to a position near the viewing side of the electrophoretic medium. More specifically, if a high-voltage electric field is applied across the electro-optic material layer, the flow of the moving charged particles towards the viewing side of the electrophoretic medium generates an air current that can even carry the uncharged particles to a position near the viewing side of the electrophoretic medium. As described above for the case of charged particle identification markers, in order to be effectively used as an identification marker, preferably the uncharged particle identification marker has at least one different property compared to other types of charged particles in the electro-optic material layer. The uncharged particle identification marker can also be a fluorescent or phosphorescent pigment. It is also preferred that the content of the charged particle identification marker is relatively low compared to the total weight content of the charged particles present in the electro-optic material layer. Thus, the charged particle identification marker can be from about 0.01 wt% to about 2 wt%, more preferably from about 0.02 wt% to about 0.5 wt%, and even more preferably from about 0.05 wt% to about 0.2 wt% of the weight of the total charged particles in the electro-optic material layer.

[0085] In another variant of the present invention, where the electro-optical device includes an encapsulated electrophoretic medium, the identification marker of the present invention can be pigment particles that are part of the microcapsule shell of the encapsulated electrophoretic medium. These particles can be charged or uncharged. It has been observed that in the case of the above encapsulation process, where polar pigment particles are present in the emulsion, some or all of the polar pigment particles become part of the shell of the electrophoretic medium rather than being present inside the microcapsules. Visual, microscopic, or spectroscopic determination of the encapsulated electrophoretic medium can then verify the electro-optic material layer and the corresponding electro-optical device (or FPL). Preferably, the content of the polar particle identification marker is relatively low compared to the total weight content of the charged particles present in the electro-optic material layer. Thus, the charged particle identification marker can be from about 0.01 wt% to about 0.5 wt%, more preferably from about 0.02 wt% to about 0.3 wt%, and even more preferably from about 0.05 wt% to about 0.1 wt% of the weight of the total charged particles in the electro-optic material layer.

[0086] Figure 5 An illustration of an example is provided where the identification marker (polar pigment particles 119) is present in the shell of the encapsulated electrophoretic medium 114. In this example, the electro-optic medium of the electro-optic layer 102 also includes black pigment particles 115A and white particles 114B. Visual, microscopic, or spectroscopic determination of the shell of the microcapsules for the presence of the polar pigment particles can then verify the electro-optic material layer and the corresponding electro-optical device.

[0087] More than one activation region can be used in different regions of the electro-optical device or FPL or dual release sheet. This can enable verification of different components or materials included in components of the electro-optical device, or FPL or dual release sheet. It can also increase the complexity of the applied stimulus or radiation emission, making the verification protocol more complex, thereby enabling encoding of additional information that can be detected during the service life of the FPL, dual release sheet or electro-optical device. In addition, the use of a combination of two or more identification markers can enable encoding and retrieval of more information about the electro-optical device, or FPL, or dual release sheet.

[0088] Example

[0089] An example of the method is evaluated according to the following description.

[0090] An aqueous dye solution containing 5 wt% of the fluorescent dye Lucifer Yellow (supplied by Sigma-Aldrich) based on the weight of the aqueous dye solution was mixed with an equal amount of an aqueous polymer solution containing 5 wt% of poly(vinyl alcohol) based on the weight of the aqueous polymer solution. The combined solution was coated onto the backplane substrate. The coating was performed such that the word "E Ink" was formed as a latent image on the backplane substrate. Lucifer Yellow is a fluorescent dye that is activated by ultraviolet light or blue visible light. This dye emits in the visible region of the electromagnetic spectrum when activated and emits at a maximum absorption wavelength longer than blue visible light. An FPL that sequentially includes a conductive light-transmissive layer, an electro-optical material, an adhesive layer, and a release film was attached to the backplane substrate after removing the release film. The attachment was performed such that the coating of the fluorescent dye was in contact with the adhesive layer of the FPL. The conductive light-transmissive layer and the backplane substrate of the electro-optical device were irradiated with a fluorescent lamp (60 W, 1050 lumens). Photographs of the front (conductive light-transmissive layer) and the back (backplane substrate) of the device were obtained. The images are provided in Figure 6A and 6C respectively. Then, the conductive light-transmissive layer and the backplane substrate of the electro-optical device were irradiated with blue light. Photographs of the front (conductive light-transmissive layer) and the back (backplane substrate) of the device were obtained. The images are provided in Figure 6B and 6D respectively.

[0091] The electro-optical material layer of the FPL used in this example is opaque. Thus, it is not surprising that no emission of the fluorescent dye is observed from the surface of the electro-optical device where the conductive transparent electrode is located, regardless of the nature of the incident light. In the case of attempting to activate the fluorescent dye with an ordinary fluorescent bulb, no emission is observed from any surface of the electro-optical device. The incident light that can enter the device from the partially transparent backplane substrate does not have a high enough frequency, i.e., it does not have a short enough wavelength to activate the fluorescent dye. However, irradiating the backplane substrate with blue light activates the fluorescent dye, which emits light in the visible region and emits at a maximum absorption wavelength longer than the wavelength of the blue incident light. As Figure 6D shown in the photograph, this emission is clearly visible to the observer when viewing the outer surface of the backplane substrate. The words "E Ink" can be clearly seen in the photograph.

[0092] Figure 7 A simplified illustration of the concept of light absorption and emission of the fluorescent dye present in the activation region is provided. In this case, the coating 109 on the backplane substrate 107 in contact with the adhesive layer 104 includes the fluorescent dye. The incident blue light 111 activates the fluorescent dye and emits light 113 with a longer wavelength visible to the observer. Conversely, when the incident blue light 111 does not encounter the fluorescent dye in its path, it is reflected back as light 112 with the same wavelength as the incident blue light. This demonstrates how the coating represents an image such as text ("E Ink") and how activation with blue light forms Figure 6D the photograph.

[0093] This example demonstrates how the fluorescent dye can be used to verify the electro-optical device.

[0094] The electro-optical device (or FPL, or double release sheet) of the present invention may also include identification marks, or combinations of identification marks, including filaments, fibers, and / or other microparticles having a unique, easily detectable structure. An example of such an identification mark is a taggant. Taggants are used in explosives, but also in commercial materials and even documents. Preferably, these filaments, fibers, and microparticles are invisible to the naked eye, but they are observable and their characteristics are detected by a microscope or they have a unique spectral signal. It is particularly important that they be invisible to the naked eye if the location of the identification marks affects the optical properties of the device, for example, if they affect the transparency of a transparent layer. The fibers and / or microparticles can be encoded by a selected combination and concentration or by marker elements. The marker elements can include color / color combinations, particle shape, metal content, different domains produced by combinations of polymers, the presence of magnetic components, etc. An example of such a taggant is a polymer microparticle material, where each polymer microparticle includes different segments having different colors. These particles can be detected with a microscope or even a magnifying glass. Another example of a taggant is a fiber material including multiple fiber components, such as different polymers and other components, melting characteristics, etc. The above examples show that such multi-component fibers and particles with unique patterns encode simple or complex information for identification purposes. The filaments, fibers, and microparticles representing the encoding can be included in one or more layers of the electro-optical device (or front plane laminate or double release sheet) or in layers adjacent to the electro-optical device (or front plane laminate or double release sheet). Even after the device has been exposed to mechanical or other types of destructive factors (such as fire or explosion), this type of identification mark can be used to identify or authenticate the device because the filaments, fibers, and microparticles can be collected from the surrounding area and analyzed.

[0095] While the preferred embodiments of the present invention have been shown and described herein, it is to be understood that such embodiments are provided by way of example only. Many variations, changes, and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, the appended claims are intended to cover all such variations that fall within the spirit and scope of the invention. If there is any inconsistency between the content of this application and any patents and applications incorporated herein by reference, the content of this application shall control to the extent necessary to resolve such inconsistency.

Claims

1. An electro-optical device, sequentially comprising: a. A conductive light-transmitting layer; b. An electro-optical material layer; c. An adhesive layer; And d. A backplane substrate including a plurality of pixel electrodes configured to apply an electric potential between the conductive light-transmitting layer and the pixel electrodes; Wherein the electro-optical device includes an activation region having an identification marker that emits radiation with a characteristic wavelength profile when stimulated to be activated, and wherein the activation region is located within or adjacent to a layer of the electro-optical device, wherein the electro-optical material layer includes an electrophoretic medium, the electrophoretic medium includes a plurality of first particles and a plurality of second particles dispersed in a hydrophobic oil, wherein the first particles are charged, and wherein the second particles are the identification marker, and its content is 0.01% to 2% by weight of the total particle content of the electrophoretic material, and wherein the second particles can be distinguished from the first particles and any other particles present in the electrophoretic medium through visual inspection, microscopy, or spectroscopy of the electro-optical device.

2. The electro-optical device according to claim 1, wherein the second particles are charged.

3. The electro-optical device according to claim 1, wherein the second particles are not charged.

4. An electro-optical device, sequentially comprising: a. A conductive light-transmitting layer; b. An electro-optical material layer; c. An adhesive layer; And d. A backplane substrate including a plurality of pixel electrodes configured to apply an electric potential between the conductive light-transmitting layer and the pixel electrodes; Wherein the electro-optical device includes an activation region having an identification marker that emits radiation with a characteristic wavelength profile when stimulated to be activated, and wherein the activation region is located within or adjacent to a layer of the electro-optical device, wherein the electro-optical material layer includes an electrophoretic medium, the electrophoretic medium includes a plurality of first particles dispersed in a hydrophobic oil, wherein the first particles are charged, and wherein the electrophoretic medium is encapsulated in a plurality of microcapsules having microcapsule shells, wherein a plurality of third pigment particles are part of the microcapsule shells, and wherein the third particles are the identification marker, and its content is 0.01% to 0.5% by weight of the total particle content of the electrophoretic material, and wherein the third particles can be distinguished from the first particles and any other particles in the electrophoretic medium through visual inspection, microscopy, or spectroscopy of the electro-optical device.

5. A front-plane laminate for manufacturing an electro-optical device, sequentially comprising: a. A conductive light-transmitting layer; b. An electro-optical material layer; c. An adhesive layer; And d. A release film; Wherein the front planar laminate includes an activation region having an identification marker that emits radiation having a characteristic wavelength profile when stimulated to activate, and wherein the activation region is located within a layer of the front planar laminate or adjacent to a layer of the front planar laminate, wherein the electro-optic material layer includes an electrophoretic medium that includes a plurality of first particles and a plurality of second particles dispersed in a hydrophobic oil, wherein the first particles are charged or uncharged, and wherein the second particles are the identification marker and are present in an amount of 0.01 wt% to 2 wt% by weight of the total particle content of the electrophoretic material, and wherein the second particles can be distinguished from the first particles and any other particles in the electrophoretic medium via visual inspection, microscopy, or spectroscopy of the front planar laminate.

6. A double release sheet for manufacturing an electro-optic device, sequentially comprising: a. A first release film; b. A first adhesive layer; c. An electro-optic material layer; d. An adhesive layer; and e. A second release film; Wherein the double release sheet includes an activation region having an identification marker that emits radiation having a characteristic wavelength profile when stimulated to activate, and wherein the activation region is located within a layer of the double release sheet or adjacent to a layer of the double release sheet, wherein the electro-optic material layer includes an electrophoretic medium that includes a plurality of first particles and a plurality of second particles dispersed in a hydrophobic oil, wherein the first particles are charged or uncharged, and wherein the second particles are the identification marker and are present in an amount of 0.01 wt% to 2 wt% by weight of the total particle content of the electrophoretic material, and wherein the second particles can be distinguished from the first particles and any other particles in the electrophoretic medium via visual inspection, microscopy, or spectroscopy of the double release sheet.

7. A method for verifying an electro-optic device and any of its components, comprising the steps of: Providing an electro-optic device that sequentially includes a conductive light-transmissive layer, an electro-optic material layer, an adhesive layer, and a backplane substrate including a plurality of pixel electrodes configured to apply an electric potential between the conductive light-transmissive layer and the pixel electrodes, wherein the electro-optic device includes an activation region having an identification marker that emits radiation having a characteristic wavelength profile when activated, and wherein the activation region is located within a layer of the electro-optic device or adjacent to a layer of the electro-optic device, wherein the electro-optic material layer includes an electrophoretic medium that includes a plurality of first particles dispersed in a hydrophobic oil, wherein the first particles are charged, and wherein the electrophoretic medium further includes a plurality of second particles, wherein the second particles are the identification marker and are present in an amount of 0.01 wt% to 2 wt% by weight of the total particle content of the electrophoretic material, and wherein the second particles can be distinguished from the first particles and any other particles present in the electrophoretic medium via visual inspection, microscopy, or spectroscopy of the electro-optic device; Activating the identification marker by stimulation; Detect the emitted electromagnetic radiation caused by the identification mark; and Determine the authenticity of the electro-optical device or any of its components or determine the manufacturing batch of the electro-optical device or any of its components.

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