Electro-optic displays with edge seal components and methods of making the same

Abstract

To provide electro-optic displays with edge seal components and methods of making the same.SOLUTION: An electro-optic display includes a backplane with at least one electrode, a layer of an electro-optic material disposed adjacent to the backplane, and a light-transmissive electroconductive layer disposed on the opposite side of the layer of electro-optic material from the backplane. The electro-optic display also includes a rod member disposed laterally adjacent to the backplane, the electro-optic material, and the light-transmissive electroconductive layer. A first barrier layer is disposed adjacent to the light-transmissive electroconductive layer and a first side of the rod member, and a second barrier is layer disposed on the backplane and a second side of the rod member. The second side is the opposite side of the rod member from the first side. A flexible barrier tape extends from an edge portion of the first barrier layer, around the rod member, to an edge portion of the second barrier layer.SELECTED DRAWING: Figure 1

Description

Background Art

[0001] (Cross - reference to related applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 313,974, filed Feb. 25, 2022, the entire content of which is incorporated herein by reference. Further, the entire content of any patent, published application, or other published writing referenced herein is incorporated herein by reference in its entirety.

[0002] The present invention relates to an electro - optical display having an edge seal. The present invention also provides a process for the production of such an electro - optical display. The present invention is particularly, but not exclusively, intended for use in combination with a display comprising an encapsulated electrophoretic medium. However, the present invention can also utilize various other types of electro - optical media, which are "solid" in the sense that they have a solid outer surface, but the media may have internal cavities and often do have internal cavities, which contain a fluid (either a liquid or a gas). Such "solid electro - optical displays" include encapsulated electrophoretic displays, encapsulated liquid crystal displays, and other types of displays discussed below.

[0003] An electro - optical display comprises a layer of electro - optical material, and the term is used herein to refer to a material having first and second display states with at least one different optical property, in its conventional meaning in the field of imaging technology, and which is changed from its first display state to its second display state by the application of an electric field to the material. The optical property is typically a color perceptible to the human eye, but may also be another optical property such as a pseudo - color in the sense of a change in reflectivity of electromagnetic wavelengths outside the visible range in the case of a display intended for machine reading, optical transmittance, reflectivity, or luminescence.

[0004] As used herein, the terms "bistable" and "bistability" refer to a display comprising a display element having first and second display states with at least one different optical property, such that after any given element is driven using an addressing pulse of finite duration to assume either the first or second display state, after the addressing pulse has ended, the state of the display element persists for at least several times, e.g., at least four times, the minimum duration of the addressing pulse required to change its state. U.S. Patent Application Publication No. 2002 / 0180687 shows that some particle-based electrophoretic displays capable of grayscale are stable not only in their extreme black and white states, but also in their intermediate gray states, and the same has been shown for several other types of electro-optic displays. Displays of this type are properly referred to as "multi-stable" rather than bistable, but for convenience, the term "bistable" may be used herein to encompass both bistable and multi-stable displays.

[0005] Several types of electro-optical displays are known. One type of electro-optical display is, for example, of the rotating dichroic member type as described in U.S. Pat. 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 (this type of display is often referred to as a "rotating dichroic ball" display, although in some of the patents referred to above, the rotating member is not spherical, so the term "rotating dichroic member" is preferred as being more accurate). Such displays use a number of small bodies (typically spherical or cylindrical) having two or more segments with different optical properties and an internal dipole. These bodies are suspended in cavities filled with a liquid within a matrix, and the cavities are filled with liquid such that the bodies can rotate freely. The appearance of the display is changed by applying an electric field thereto and thus rotating the bodies to various positions and varying the position of the segments of the bodies visible through the viewing surface. This type of electro-optical medium is typically bistable.

[0006] Another type of electro-optical display uses an electrochromic medium in the form of a nanochromic film, for example, an electrochromic medium comprising an electrode formed at least in part from a semiconductor metal oxide and a plurality of dye molecules attached to the electrode capable of reversible color change. See, for example, O’Regan, B., et al., Nature 1991, 353, 737 and Wood, D., Information Display, 18(3), 24 (March 2002). See also Bach, U., et al., Adv. Mater., 2002, 14(11), 845. This type of nanochromic film is also described, for example, in U.S. Pat. Nos. 6,301,038, 6,870,657, and 6,950,220. This type of medium is also typically bistable.

[0007] Over the years, another type of electro-optical display that has been the subject of intensive research and development is the particle-based electrophoretic display, in which a plurality of charged particles move through a suspension fluid under the influence of an electric field. Electrophoretic displays can have attributes of good brightness and contrast, wide viewing angles, bistable states, and low power consumption when compared to liquid crystal displays. Nevertheless, problems associated 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 sediment, resulting in an inappropriate usable life for these displays.

[0008] As described above, an electrophoretic medium requires the presence of a fluid. In most prior art electrophoretic media, this fluid is a liquid, although electrophoretic media can also be produced using a gaseous fluid. See, for example, Kitamura, T., et al., “Electrical toner movement for electronic paper-like display”, IDW Japan, 2001, Paper HCS1-1 and Yamaguchi, Y., et al., “Toner display using insulative particles charged triboelectrically”, IDW Japan, 2001, Paper AMD4-4). See also U.S. Patent Application Publication No. 2005 / 0001810, European Patent Applications Nos. 1,462,847, 1,482,354, 1,484,635, 1,500,971, 1,501,194, 1,536,271, 1,542,067, 1,577,702, 1,577,703, and 1,598,694, and International Applications Nos. WO2004 / 090626, WO2004 / 079442, and WO2004 / 001498. Such gas-based electrophoretic media are likely to be affected by the same type of problems due to particle sedimentation as liquid-based electrophoretic media when, for example, the media are used in an orientation that allows such sedimentation in a sign where the media are disposed in a vertical plane. In fact, particle sedimentation is considered to be a more serious problem in gas-based electrophoretic media than in liquid-based electrophoretic media because of the lower viscosity of the gaseous suspension fluid compared to the viscosity of the liquid that allows for faster sedimentation of the electrophoretic particles.

[0009] A number of patents and applications assigned to, or in the name of, the Massachusetts Institute of Technology (MIT) and E Ink Corporation that describe encapsulated electrophoretic media have recently been published. Such encapsulated media comprise a number of small capsules, each of which itself includes an internal phase containing particles movable by electrophoresis suspended in a liquid suspension medium, and a capsule wall surrounding the internal phase. Typically, the capsules themselves are held within a polymeric binder to form a coherent layer positioned between two electrodes. This type of encapsulated media is described, for example, [Chem.] [Chem.] as described in

[0010] Many of the aforementioned patents and applications recognize that the walls surrounding discrete microcapsules in an encapsulated electrophoretic medium 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, and that the discrete droplets of electrophoretic fluid within such a polymer dispersed electrophoretic display can be considered capsules or microcapsules even if no discrete capsule membrane is associated with each individual droplet. See, for example, U.S. Patent No. 6,866,760, supra. Thus, for the purposes of this application, such polymer dispersed electrophoretic media are considered a subclass of encapsulated electrophoretic media.

[0011] Related types of electrophoretic displays are so-called "microcell electrophoretic displays." In a microcell electrophoretic display, charged particles and a suspension fluid are not encapsulated within microcapsules, but instead are held within a plurality of cavities formed within a carrier medium, typically a polymeric film. See, for example, International Application Publication No. WO02 / 01281 and Published U.S. Application No. 2002 / 0075556, both assigned to SiPix Imaging, Inc.

[0012] Another type of electro-optic display is an electrowetting display developed by Philips and described in Hayes, R.A., et al. “Video-Speed Electronic Paper Based on Electrowetting”, Nature, 425, 383-385 (2003). U.S. Patent No. 7,420,549 shows that such an electrowetting display can be made bistable.

[0013] Other types of electro-optic materials may also be used in the present invention. Of particular note, bistable ferroelectric liquid crystal displays (FLCs) are known in the art.

[0014] Electrophoretic media are often opaque (e.g., in many electrophoretic media, the particles substantially block the transmission of visible light through the display), and can operate in a reflective mode, but many electrophoretic displays can be fabricated to operate in a so-called "shutter mode" where one display state is substantially opaque and one is light transmissive. See, for example, U.S. Pat. Nos. 6,130,774 and 6,172,798, and U.S. Pat. Nos. 5,872,552, 6,144,361, 6,271,823, 6,225,971, and 6,184,856. Dielectrophoretic displays, which, like electrophoretic displays, rely on variations in electric field strength, can operate in similar modes. See U.S. Pat. No. 4,418,346.

[0015] Encapsulated or microcell electrophoretic displays typically do not suffer from the clustering and settling failure modes of conventional electrophoretic devices and offer additional advantages such as the ability to print or coat the display on a wide 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 coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating, etc., and roll coatings such as knife over roll coating, forward and reverse roll coating, etc., gravure coating, dip coating, spray coating, meniscus coating, spin coating, brush coating, air knife coating, silk screen printing processes, electrostatic printing processes, thermal printing processes, ink jet printing processes, electrophoretic deposition, and other similar techniques.) Thus, the resulting display can be flexible. Further, since the display medium can be printed (using various methods), the display itself can be fabricated inexpensively.

[0016] An electro-optical display typically comprises a layer of electro-optical material and at least two other layers disposed on opposite sides of the electro-optical material, one of these two layers being an electrode layer. In most such displays, both layers are electrode layers, and one or both of the electrode layers are patterned so as to define the pixels of the display. For example, one electrode layer may be patterned into elongate row electrodes and the other into elongate column electrodes extending at right angles to the row electrodes, the pixels being defined by the intersections of the row and column electrodes. Alternatively, and more generally, one electrode layer has the form of a single continuous electrode and the other electrode layer is patterned into a matrix of pixel electrodes, each of which defines one pixel of the display. In another type of electro-optical display intended for use in combination with a stylus, printing head, or similar movable electrode separate from the display, only one of the layers adjacent to the electro-optical layer comprises electrodes, and the layer on the opposite side of the electro-optical layer is typically a protective layer intended to prevent the movable electrode from damaging the electro-optical layer.

[0017] The manufacture of a three-layer electrophoretic display typically involves at least one lamination operation. For example, in some of the aforementioned MIT and E Ink patents and applications, a process for manufacturing an encapsulated electrophoretic medium that includes capsules within a binder is described, where the encapsulated electrophoretic medium is coated on a flexible substrate that has indium tin oxide (ITO) or a similar conductive coating (which acts as one electrode of the final display) on a plastic film, and the capsule / binder coating is dried to form a coherent layer of the electrophoretic medium that adheres firmly to the substrate. Separately, a backplane is prepared that contains an array of pixel electrodes and an appropriate arrangement of conductors and connects the pixel electrodes to a drive circuitry. To form the final display, the substrate having the capsule / binder layer thereon is laminated to the backplane using a lamination adhesive (a very similar process can be used to prepare an electrophoretic display that can be used in combination with a stylus or similar movable electrode by replacing the backplane with a simple protective layer such as a plastic film over which a stylus or other movable electrode can slide). In one form of such a 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. Similar manufacturing techniques can be used in combination with other types of electro-optic displays. For example, a microcell electrophoretic medium or a rotating dichroic member medium may be laminated to the backplane in substantially the same manner as the encapsulated electrophoretic medium.

[0018] As discussed in the aforementioned U.S. Patent No. 6,982,178, many of the components used in solid electro-optical displays and the methods used to manufacture such displays are derived from the technologies used in liquid crystal displays (LCDs) (which are, of course, also electro-optical displays), but use a liquid rather than a solid medium. For example, a solid electro-optical display may utilize an active matrix backplane comprising an array of transistors or diodes and a corresponding array of pixel electrodes on a transparent substrate, and a "continuous" front electrode (in the sense of electrodes, over a plurality of pixels, typically extending across the entire display), and these components are essentially the same as those in an LCD. However, the methods used to assemble an LCD cannot be used in combination with a solid electro-optical display. An LCD is typically assembled by forming the backplane and the front electrode on separate glass substrates, then adhering these components together with a small opening left between them, placing the resulting assembly under vacuum, and immersing the assembly in a bath of liquid crystal so that the liquid crystal flows through the opening between the backplane and the front electrode. Finally, with the liquid crystal in place, the opening is sealed to provide the final display.

[0019] This LCD assembly process cannot be easily transferred to a solid electro-optical display. Since the electro-optical material is a solid, it must be present between the backplane and the front electrode before these two complete parts are adhered to each other. Further, in contrast to a liquid crystal material that is simply placed between the front electrode and the backplane without being attached to either, a solid electro-optical medium typically needs to be adhered to both, and in most cases, it is easier to form the solid electro-optical medium on the circuit network-containing backplane than on the front electrode. Thus, the front electrode / electro-optical medium combination is then typically laminated to the backplane by coating the entire surface of the electro-optical medium with an adhesive and laminating under heat, pressure, and possibly vacuum.

[0020] Electro-optic displays are often costly. For example, the cost of a color LCD, such as those found in portable computers, typically represents a significant portion of the overall cost of the computer. As the use of electro-optic displays spreads to devices such as mobile phones and personal digital assistants (PDAs), which are much less expensive than portable computers, there is great pressure to reduce the cost of such displays. The ability to form a layer of a solid electro-optic medium on a flexible substrate by printing techniques opens the possibility of reducing the cost of the electro-optic components of the display by using mass production techniques such as roll-to-roll coating, which use commercial equipment used for the production of coated paper, polymer films, and similar media. However, such equipment is costly, and the area of electro-optic media currently on the market may typically be insufficient to justify the dedicated equipment that may be required to transfer the coated media from a commercial coating plant to the factory where it will be used for the final assembly of the electro-optic display without damaging the relatively fragile layer of the electro-optic media.

[0021] Also, most prior art methods for the final lamination of electrophoretic displays are essentially batch methods, in which the electro-optic medium, lamination adhesive, and backplane are only combined together immediately prior to final assembly, and it is desirable to provide a method that is better suited for mass production.

[0022] U.S. Patent No. 6,982,178, supra, describes a method of assembling a solid electro-optical display (including a particle-based electrophoretic display), which is well-suited for high-volume manufacturing. In essence, the present co-pending application describes a so-called "front plane laminate" ("FPL"), which, in turn, comprises a light-transmissive conductive layer, a layer of a solid electro-optical medium in electrical contact with the conductive layer, an adhesive layer, and a release sheet. Typically, the light-transmissive conductive layer is carried on a light-transmissive substrate, which is preferably flexible in the sense that the substrate can be manually wound around the circumference of a drum (e.g., 10 inches (254 mm) in diameter) without permanent deformation. The term "light-transmissive" is used in this patent and in this specification to mean that the layer so designated transmits sufficient light to enable an observer looking through the layer to observe changes in the display state of the electro-optical medium, which will typically be visible through the conductive layer and an adjacent substrate (if present). The substrate is typically a polymer film and will usually 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 may, for convenience, be, for example, a thin metal layer of aluminum or ITO, or a conductive polymer. A poly(ethylene terephthalate) (PET) film coated with aluminum or ITO is commercially available, for example, from E.I. duPont de Nemours & Company (Wilmington DE) as "aluminized Mylar" ("Mylar" is a registered trademark), and such commercial materials can be used with good results in front plane laminates.

[0023] The aforementioned U.S. Patent No. 6,982,178 also describes a method for testing an electro-optical medium within a front plane laminate prior to incorporation of the front plane laminate into a display. In this test method, the release sheet comprises a conductive layer, and a voltage sufficient to change the optical state of the electro-optical medium is applied between the conductive layer and a conductive layer on the opposite side of the electro-optical medium. Observation of the electro-optical medium then reveals any defects within the medium, and thus will avoid the lamination of a defective electro-optical medium into the display, along with the cost resulting in scrapping not only the defective front plane laminate but the entire display.

[0024] The aforementioned U.S. Patent No. 6,982,178 also describes a second method for testing an electro-optical medium within a front plane laminate by placing an electrostatic charge on the release sheet and thus forming an image on the electro-optical medium. This image is then observed in the same manner as described above to detect any defects within the electro-optical medium.

[0025] The aforementioned 2004 / 0155857 describes a so-called "double release film", 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 comprises a layer of solid electro-optical medium sandwiched between two adhesive layers, with one or both of the adhesive layers being covered by a release sheet. Another form of the double release sheet comprises a layer of solid electro-optical medium sandwiched between two release sheets. Both forms of the double release film are generally intended for use in a process similar to the process for assembling an electro-optical display from the front plane laminate already described, but with 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, although the order of these two laminations can be reversed if desired.

[0026] U.S. Patent No. 7,839,564 describes a so-called "inverted front plane stack," which is a variation of the front plane stack described in the aforementioned U.S. Patent No. 6,982,178. This inverted front plane stack comprises, in order, at least one of a light-transmissive protective layer and a light-transmissive conductive layer, an adhesive layer, a layer of a solid electro-optic medium, and a release sheet. This inverted front plane stack is used to form an electro-optic display having a layer of a lamination adhesive between the electro-optic layer and the front electrode or front substrate, and there may or may not be a second, typically thin, layer of an adhesive between the electro-optic layer and the backplane. Such an electro-optic display can combine good resolution and good low-temperature performance.

[0027] The aforementioned U.S. Patent No. 7,839,564 also describes various methods designed for the mass production of electro-optic displays using an inverted front plane stack. Some forms of these methods are "multi-up" methods designed to enable the lamination of components for multiple electro-optic displays at once.

[0028] U.S. Patent No. 6,982,178 also describes the importance of protecting electro-optical media from environmental contaminants, as some electro-optical media are highly sensitive to humidity and ultraviolet radiation and most such media are subject to mechanical damage. This patent illustrates in FIG. 10 a process in which, in the same lamination operation by which a front plane laminate is laminated to a back plane, a protective film is laminated over the front plane laminate, such a protective film being capable of protecting the electro-optical media against the ingress of moisture, other liquids, and some gases. However, even when using such a protective film, the edges of the electro-optical media are still exposed to the environment, and this patent teaches that it is also advisable for the display to include an edge seal, which serves to prevent the ingress of moisture and other contaminants around the outer edges of the display. Various types of edge seals are illustrated in FIGS. 11-17 of this patent. Such edge seals can consist of metallized foil or other barrier foils adhered over the edges of the FPL, dispensed sealants (which are thermally, chemically, and / or radiation cured), polyisobutylene or acrylate-based sealants, etc. Hybrid radiation and thermosetting sealants (i.e., UV curable with heat after baking) have been found to offer certain advantages in display system performance. The Threebond 30Y-491 material (manufactured by Threebond Corporation, Cincinnati, OH) has been found to have favorable water vapor barrier properties, low viscosity at high temperatures for easy dispensing of the edge seal material, good wetting characteristics, and manageable curing properties. Those skilled in the art and those knowledgeable about advanced sealants will be able to identify other sealants that provide equivalent performance.

[0029] FIG. 20 of the aforementioned U.S. Patent No. 6,982,178 shows an electro-optical display having a front protection layer and an edge seal. This display generally resembles a backplane used in combination with a liquid crystal display and includes a matrix of pixel electrodes, associated thin film transistors and conductors for independently controlling the voltage applied to the pixel electrodes, a thin film transistor (TFT) backplane. A tape connection package is connected to the peripheral portion of the backplane, includes a driver integrated circuit (for controlling the operation of the display), and the tape connection package is also connected to a printed circuit board that contains additional circuitry for controlling the operation of the display.

[0030] On the upper surface of the backplane (as shown in FIG. 20 above), a layer of laminated adhesive, a layer of electro-optical medium, a front electrode, and a front substrate are disposed. Both the front electrode and the front substrate are preferably formed from a polymer film coated with indium tin oxide. As already mentioned, such coated films are commercially readily available. The laminated adhesive layer, electro-optical layer, front electrode, and front substrate are all derived from a front plane laminate laminated to the backplane. Portions of the front electrode and front substrate extend beyond the electro-optical layer. In the extended portions of the front electrode and front substrate, conductive vias formed from silver ink electrically connect the front electrode to the circuitry provided on the backplane, while the adhesive layer secures the extended portion of the front electrode to the backplane.

[0031] Over the front substrate, a first layer of optically transparent adhesive, a barrier film, a second layer of optically transparent adhesive, and a relatively thick protective film provided on its exposed surface with an anti-reflective coating are continuously disposed. The protective film acts to block ultraviolet radiation from reaching the electro-optical layer and also prevents moisture or other contaminants in the atmosphere from reaching this layer.

[0032] To form a complete seal around the electro-optical layer, the barrier film, the second layer of optically transparent adhesive, and the protective film are all made larger in both dimensions than the front substrate, and thus these layers have peripheral portions that extend or "overhang" from the outer edge of the front substrate. To complete the sealing of the electro-optical layer, a curable edge seal material is typically injected via a syringe into the area of the overhang, cured, and forms an edge seal that completely surrounds the electro-optical layer.

[0033] Figure 3 of the aforementioned U.S. Patent No. 7,649,674 shows another embodiment of an electro-optical display having a front protective or barrier layer and an edge seal. The display also includes a backplane, on which a front substrate including a layer of laminated adhesive, a layer of electro-optical medium, and a conductive film or coating is disposed. The backplane is larger in both length and width dimensions than the layers of laminated adhesive, electro-optical medium, and front substrate. Thus, the peripheral portion of the backplane extends beyond the outer edges of these layers all around their peripheries.

[0034] The display further includes a front protective or barrier sheet laminated or otherwise applied on the front substrate. The barrier sheet is made larger in both length and width dimensions than the front substrate such that the barrier sheet has a peripheral portion that extends or "overhangs" from the outer edge of the front substrate. The overhang portion of the barrier sheet is "sandwiched" downwardly across the edges of the laminated adhesive, electro-optical medium, and front substrate and sealed to the peripheral portion of the backplane to form a sandwiched edge seal. The barrier sheet can be melted onto the surface of the backplane using, for example, laser or ultrasonic welding. Alternatively, an adhesive can be used to secure the overhang portion of the barrier sheet to the backplane.

Prior Art Documents

Patent Documents

[0035]

Patent Document 1

[0036] Edge seals such as those incorporated into FIG. 20 of U.S. Patent No. 6,982,178, summarized above, can be effective in preventing the ingress of moisture and other environmental contaminants into the electro-optical medium. However, one of the advantages of encapsulated electrophoresis and other electro-optical media, such as organic light-emitting diodes (OLEDs) and microcell media, is that they are flexible enough to be used in flexible displays. However, the aforementioned edge seals and similar edge seals, once fully cured, are not suitable for use in flexible displays because the curable edge seal material imparts rigidity to the display. These types of edge seals can also add complexity to the display manufacturing process, which is associated with accurately dispensing the seal material around the periphery of the backplane.

[0037] Edge seals incorporated into FIG. 3 of U.S. Patent No. 7,649,674, summarized above, maintain the flexibility of the electro-optical display because they do not utilize curable edge seal material. However, it has been found that the area where the sandwiched portion of the barrier sheet is adhered to the surface of the backplane can become a moisture diffusion path along the edge of the electro-optical display.

[0038] Means for reducing or alleviating the edge moisture diffusion effect typically include increasing the width of the optically inactive area around the outer periphery of the electro-optical material and / or increasing the width of the sandwiched portion of the barrier sheet. However, implementing any of these alleviating means imposes a trade-off on the design of the end product incorporating the electro-optical display. For example, with respect to a display housing of a given height and width, increasing the width of the inactive area around the edge of the electro-optical material or the sandwiched portion of the barrier sheet effectively reduces the visible area of the display, and a housing with a wider bezel portion is required to conceal these unusable areas. Alternatively, if the size of the visible area is a fixed design requirement, the dimensions of the display housing must be increased to achieve the required visible area.

[0039] In addition, when producing large flexible displays that can be used, for example, to wrap around a bus or a building, the edges are more likely to be damaged during handling and placement. This also applies to aftermarket variable transmittance films that can be disposed on existing windows within a building, or on existing windows within a vehicle such as a passenger bus window or an automobile moonroof. If the edges or corners of such a device are damaged, moisture ingress can reduce performance or even result in an electrical short circuit or delamination.

[0040] Therefore, the edge sealing techniques described herein include features for addressing the drawbacks of conventional edge seals.

[0041] Thus, on one aspect, the subject matter presented herein is a backplane including at least one electrode, a layer of electro-optical material disposed adjacent to the backplane, a light-transmissive conductive layer disposed on the side opposite from the backplane of the layer of electro-optical material, a rod member disposed adjacent to the side of the backplane, the layer of electro-optical material, and the light-transmissive conductive layer, a first barrier layer disposed adjacent to the first side of the light-transmissive conductive layer and the rod member, and a second barrier layer disposed on the second side of the backplane and the rod member, where the second side is on the opposite side from the first side of the rod member, and a flexible barrier tape extending from the edge portion of the first barrier layer, around the rod member, to the edge portion of the second barrier layer, to provide an electro-optical display.

[0042] In some embodiments, the electro-optical display further includes an edge seal material within the flexible barrier tape. The edge seal material is disposed at a first end portion of the rod member adjacent to a first corner of the electro-optical display and at a second end portion of the rod member adjacent to a second corner of the electro-optical display.

[0043] In some embodiments, the edge seal material is a UV-curable resin. In some embodiments, the edge seal material has a water vapor transmission rate of 2 - 3 g / m 2 / day at 60 °C and 90% relative humidity. In some embodiments, the barrier tape further includes an adhesive layer on the surface of the barrier tape that contacts the edge portion of the first barrier layer, the rod member, and the edge portion of the second barrier layer.

[0044] In some embodiments, the rod member is cylindrical and has an average diameter of about 0.254 mm to about 2.54 mm. In some embodiments, the rod member is integrated into the barrier tape. In some embodiments, the rod member is positioned substantially along the longitudinal center of the barrier tape.

[0045] In some embodiments, the barrier tape further includes a layer of electrically insulating material disposed on a surface of the barrier tape that contacts an edge portion of the first barrier layer, the rod member, and an edge portion of the second barrier layer. In some embodiments, the barrier tape further comprises a layer of metal foil disposed on a surface of the barrier tape opposite the surface that contacts an edge portion of the first barrier layer, the rod member, and an edge portion of the second barrier layer. In some embodiments, the barrier tape comprises a layer of adhesive material disposed on a first half of the lengthwise surface of the barrier tape and a layer of metal foil disposed on a second half of the lengthwise surface of the barrier tape. In some embodiments, the barrier tape comprises a colorant.

[0046] In another aspect, the subject matter presented herein provides an electro-optic display comprising a backplane including at least one electrode, a layer of electro-optic material disposed adjacent to the backplane, a light-transmissive conductive layer disposed on an opposite side of the layer of electro-optic material from the backplane, and corner barrier seals disposed at each corner of the electro-optic display. The corner barrier seal includes a barrier material including a square shape in an unfolded state and first, second, and third fold lines, the first and second fold lines being perpendicular to each other, the third fold line being substantially 45 degrees from the first and second fold lines, the first, second, and third fold lines bisecting each other and the barrier material, the first and second fold lines being folded in an upward direction, the third fold line being folded in a downward direction, and first and second corner pockets being formed.

[0047] In some embodiments, the electro-optic display further includes the step of forming the square-shaped barrier material in an X shape in an unfolded state. In some embodiments, the corner barrier seal further includes an adhesive layer disposed on inner surfaces of the first and second corner pockets.

[0048] In some embodiments, the layer of electro-optic material and the optically transparent conductive layer are disposed within the first corner pocket of each corner seal, and the backplane is disposed within the second corner pocket of each corner seal. In some embodiments, the layer of electro-optic material, the optically transparent conductive layer, and the backplane are disposed within the first or second corner pocket of each corner seal.

[0049] In some embodiments, the electro-optic display further includes a first barrier layer disposed on the optically transparent conductive layer and the first surface of each corner seal, and a second barrier layer disposed on the backplane and the second surface of each corner seal. In some embodiments, the first and second barrier layers each extend beyond the edges of the optically transparent conductive layer, the layer of electro-optic material, and the backplane, leaving peripheral portions of the first and second barrier layers, and the peripheral portions of the first and second barrier layers are adhered to each other, thereby sealing the edges of the electro-optic display.

[0050] In some embodiments, the electro-optic display further includes an edge seal component that extends around the periphery of the electro-optic display across the edge portions of the first barrier layer and the edge portions of the second barrier layer. In some embodiments, the edge seal component is a barrier tape that includes polychlorotrifluoroethylene or aluminum oxide.

[0051] In another aspect, the subject matter presented herein provides a process for forming an electro-optical display. The process includes providing a front plane laminate including a layer of electro-optical material and a light transmissive conductive layer; providing a backplane including at least one pixel electrode, the backplane being larger than the front plane subassembly in length and width dimensions; laminating the front plane subassembly to the backplane; dispensing a curable edge seal material around the periphery of the backplane adjacent to the outer edge of the front plane subassembly; partially curing the curable edge seal material; laminating a barrier layer over the front plane subassembly and the partially cured edge seal material, the barrier layer being sized to overhang from the partially cured edge seal material; adhering the overhanging portion of the barrier layer to the surface of the backplane; and fully curing the curable edge seal material.

[0052] In some embodiments, the surface of the barrier layer comprises a layer of pressure sensitive adhesive. In some embodiments, the step of partially curing the curable edge seal material includes curing the curable edge seal material over a period of about 15 to 40 seconds.

[0053] In some embodiments, the curable edge seal material has a water vapor transmission rate of 2 - 3 g / m 2 / day at 60 °C and 90% relative humidity. In some embodiments, the curable edge seal material is a polymer including epoxy, urethane, acrylate, or combinations thereof. In some embodiments, the curable edge seal material is UV-curable.

[0054] In another aspect, the subject matter presented herein provides an electro-optical display formed using the process described above.

[0055] In another aspect, the subject matter of this specification provides a variable transmittance window that includes a display stack, a substrate, and an edge seal material. The display stack includes a layer of electro-optic material disposed between a bottom surface of an upper optically transparent conductive layer and an upper surface of a bottom optically transparent conductive layer, and a barrier layer disposed on an upper surface of the upper optically transparent conductive layer. In some embodiments, a first adhesive layer is disposed between the barrier layer and the upper optically transparent conductive layer. The display stack is disposed on the substrate. In some embodiments, the length and width of the substrate exceed the length and width of the display stack. In some embodiments, a second adhesive layer is disposed between the display stack and the substrate. The edge seal material is disposed along a periphery of the display stack and on a portion of the substrate. The edge seal material includes a first horizontal section disposed on a portion of an upper surface of the barrier layer, a vertical section disposed adjacent to an entire outer edge of the display stack, and a second horizontal section disposed on a portion of an upper surface of the substrate. In some embodiments, a third adhesive layer is disposed between the edge seal material and both the display stack and the substrate.

[0056] In some embodiments, the layer of electro-optic material includes a plurality of microcells. In some embodiments, the layer of electro-optic material includes a layer of seal material disposed on open ends of the plurality of microcells. In some embodiments, each of the plurality of microcells includes a protruding structure. In some embodiments, the protruding structure is formed from one or more geometric shapes. In some embodiments, the protruding structure is formed from a conical shape formed on a cylindrical shape.

[0057] These and other aspects of the invention will become apparent in light of the following description. The present invention provides, for example, the following. (Item 1) An electro-optic display, a backplane having at least one electrode, a layer of electro-optic material disposed adjacent to the backplane, A light-transmissive conductive layer disposed on the side opposite to the backplane of the layer of the electro-optical material; A rod member disposed adjacent to the side of the backplane, the layer of the electro-optical material, and the light-transmissive conductive layer; A first barrier layer disposed adjacent to the first side of the light-transmissive conductive layer and the rod member; A second barrier, which is a layer disposed on the second side of the backplane and the rod member, wherein the second side is on the side opposite to the first side of the rod member; A flexible barrier tape extending from the edge portion of the first barrier layer, around the rod member, to the edge portion of the second barrier layer; An electro-optical display comprising the above. (Item 2) Further comprising an edge seal material within the flexible barrier tape, the edge seal material being Disposed at a first end portion of the rod member adjacent to a first corner of the electro-optical display; And a second end portion of the rod member adjacent to a second corner of the electro-optical display. The electro-optical display according to Item 1, disposed at the above positions. (Item 3) The electro-optical display according to Item 2, wherein the edge seal material is a UV-curable resin. (Item 4) The electro-optical display according to Item 2, wherein the edge seal material has a water vapor transmission rate of 2 - 3 g / m 2 / day at 60 °C and 90% relative humidity. (Item 5) The electro-optical display according to Item 1, wherein the barrier tape further comprises an adhesive layer on the surface of the barrier tape that contacts the edge portion of the first barrier layer, the rod member, and the edge portion of the second barrier layer. (Item 6) The electro-optical display according to Item 1, wherein the rod member is cylindrical and has an average diameter of about 0.254 mm to about 2.54 mm. (Item 7) The electro-optical display according to item 5, wherein the rod member is integrated into the barrier tape. (Item 8) The electro-optical display according to item 7, wherein the rod member is positioned substantially along the central portion in the longitudinal direction of the barrier tape. (Item 9) The electro-optical display according to item 1, wherein the barrier tape further comprises a layer of electrically insulating material disposed on the surface of the barrier tape that contacts the edge portion of the first barrier layer, the rod member, and the edge portion of the second barrier layer. (Item 10) The electro-optical display according to item 1, wherein the barrier tape further comprises a metal foil layer disposed on the surface of the barrier tape opposite to the surface that contacts the edge portion of the first barrier layer, the rod member, and the edge portion of the second barrier layer. (Item 11) The electro-optical display according to item 1, wherein the barrier tape comprises a layer of adhesive material disposed on the first half of the longitudinal surface of the barrier tape and a layer of metal foil disposed on the second half of the longitudinal surface of the barrier tape. (Item 12) The electro-optical display according to item 1, wherein the barrier tape comprises a colorant. (Item 13) An electro-optical display, a backplane comprising at least one electrode, a layer of electro-optical material disposed adjacent to the backplane, a light-transmissive conductive layer disposed on the side opposite to the backplane of the layer of electro-optical material, corner barrier seals disposed at each corner of the electro-optical display, wherein the corner barrier seals comprise a barrier material having a square shape in the unfolded state, first, second, and third folding lines and the first and second folding lines are perpendicular to each other, and the third folding line is substantially 45 degrees from the first and second folding lines. The first, second, and third folding lines bisect each other and the barrier material, the first and second folding lines are folded in an upward direction, and the third folding line is folded in a downward direction to form first and second corner pockets, corner barrier seals, and An electro-optical display comprising. (Item 14) The electro-optical display according to item 13, further comprising forming the square-shaped barrier material in an X shape in the unfolded state. (Item 15) The electro-optical display according to item 13, wherein the corner barrier seal further comprises an adhesive layer disposed on the inner surfaces of the first and second corner pockets. (Item 16) The layer of electro-optical material and the light-transmissive conductive layer are disposed within the first corner pocket of each corner barrier seal, The backplane is disposed within the second corner pocket of each corner barrier seal. The electro-optical display according to item 13. (Item 17) The electro-optical display according to item 13, wherein the layer of electro-optical material, the light-transmissive conductive layer, and the backplane are disposed within the first corner pocket or the second corner pocket of each corner barrier seal. (Item 18) A first barrier layer disposed on the light-transmissive conductive layer and the first surface of each corner barrier seal, and a second barrier layer disposed on the backplane and the second surface of each corner barrier seal. The electro-optical display according to item 13, further comprising. (Item 19) The first and second barrier layers are each larger than the light-transmissive conductive layer, the layer of electro-optical material, and the backplane in both dimensions, leaving peripheral portions of the first and second barrier layers that extend beyond the edges of the light-transmissive conductive layer, the layer of electro-optical material, and the backplane. The peripheral portions of the first and second barrier layers are fixedly attached to each other, thereby sealing the edge of the electro-optical display. The electro-optical display according to item 18. (Item 20) The electro-optical display according to item 18, further comprising an edge seal component extending around the periphery of the electro-optical display across the edge portion of the first barrier layer and the edge portion of the second barrier layer. (Item 21) The electro-optical display according to item 18, wherein the edge seal component is a barrier tape containing polychlorotrifluoroethylene or aluminum oxide. (Item 22) A process for forming an electro-optical display, the process comprising: providing a front plane laminate comprising a layer of electro-optical material and a light-transmissive conductive layer; providing a backplane comprising at least one pixel electrode, the backplane being larger than the front plane subassembly in length and width dimensions; laminating the front plane subassembly to the backplane; dispensing a curable edge seal material around the periphery of the backplane adjacent to the outer edge of the front plane subassembly; partially curing the curable edge seal material; laminating a barrier layer across the front plane subassembly and the partially cured edge seal material, the barrier layer being sized to overhang from the partially cured edge seal material; adhering the overhanging portion of the barrier layer to the surface of the backplane; completely curing the curable edge seal material; and including. (Item 23) The process according to item 22, wherein the surface of the barrier layer comprises a layer of pressure-sensitive adhesive. (Item 24) Partially curing the curable edge seal material includes curing the curable edge seal material over about 15 - 40 seconds, the process according to item 22. (Item 25) The curable edge seal material has a water vapor transmission rate of 2 - 3 g / m 2 / day at 60 °C and 90% relative humidity, the process according to item 22. (Item 26) The curable edge seal material is a polymer including epoxy, urethane, acrylate, or a combination thereof, the process according to item 22. (Item 27) The curable edge seal material is UV - curable, the process according to item 22. (Item 28) An electro - optical display formed using the process according to item 22.

Brief Description of the Drawings

[0058]

Figure 1

[0059]

Figure 2A

Figure 2B

Figure 2C

Figure 2D

[0060]

Figure 3

[0061]

Figure 4

[0062]

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 5E

Figure 5F

[0063]

Figure 6

[0064]

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 7E

[0065]

Figure 8

[0066]

Figure 9

[0067]

Figure 10

[0068] It should be emphasized that the accompanying drawings are schematic and not to scale. In particular, for ease of illustration, the thicknesses of the various layers in the drawings do not correspond to their actual thicknesses. Also, in all the drawings, the thicknesses of the various layers are greatly exaggerated relative to their lateral dimensions.

DETAILED DESCRIPTION

[0069] Detailed Description Flexible electro-optical displays, including those that are rollable, are important new market opportunities. For example, large displays that can be stored in a compact form, which currently only have small display screens, could be useful as additional display devices on electronic devices where larger display screens would often be useful. Examples of such devices include cellular phones equipped with the function of receiving e-mail. However, such flexible electro-optical displays will typically require a seal to prevent the ingress of water vapor and other environmental contaminants that can adversely affect the electro-optical properties or operating life of the display. U.S. Pat. Nos. 6,982,178, 7,110,164, and 7,649,674, and Patent Publication No. 2004 / 0155857 all discuss seals for electro-optical displays, but most of the displays considered therein are rigid and formed on glass or a similar backplane, and additional difficulties arise in selecting a suitable sealing technique for flexible displays. Both the structural properties and barrier properties of the seal material used need to be carefully considered to provide a proper seal within the flexible display, along with the structure of the final display.

[0070] As will be discussed in detail below, there are several approaches for sealing a flexible display using a combination of a substrate, an edge seal material, and an assembly technique. For the purposes of the following discussion, the term "backplane" is used herein in accordance with its conventional meaning in the technical field of electro-optical displays and as used in the foregoing patents and published applications, and means a rigid or flexible material having one or more electrodes. The backplane may also comprise electronics for addressing the display, or such electronics may be provided in a unit separate from the backplane. In a flexible display, it is highly desirable for the backplane to provide sufficient barrier properties to prevent the ingress of moisture or other contaminants through the non-viewing side of the display (the display is, of course, typically viewed from the side remote from the backplane). If one or more additional barrier layers are required to be added to the backplane to reduce the ingress of moisture and other contaminants, the barrier layer should be positioned as close as possible to the electro-optical layer such that the edge profile of the low-barrier material is substantially or entirely absent between the front barrier layer (discussed below) and the back barrier layer.

[0071] The term "front substrate" is used herein in accordance with its conventional meaning in the art of electro-optical displays and in the foregoing patents and published applications, and means a rigid or flexible material that is light transmissive (preferably transparent). The front substrate will typically comprise at least one electrode, most commonly a single continuous front electrode extending across the entire display. Typically, the exposed surface of the front substrate forms the viewing surface through which the observer views the display, although in some of the embodiments described below, additional layers may be interposed between the front substrate and the viewing surface. Similar to the backplane, the front substrate needs to provide sufficient barrier properties to prevent the ingress of moisture and other contaminants through the viewing side of the display.

[0072] Typically, an electro-optical display includes one or more barrier layers to prevent ingress of moisture, dust, gas, etc., or to prevent egress of fluid within the display. If one or more additional layers are required to be added to the front substrate to reduce ingress of moisture and other contaminants, the barrier layer should be positioned as close as possible to the electro-optical layer such that when the barrier layer covers the display, there is little or no edge profile relative to the back substrate.

[0073] As discussed in the aforementioned U.S. Pat. Nos. 7,649,674, 6,982,178, and 7,110,164, and Patent Publication No. 2004 / 0155857, a common front substrate for an electro-optical display comprises a thin layer of ITO on PET, and such coated films are commercially readily available, for example, from Saint Gobain. In such front substrates, the ITO layer serves as a barrier material, but in practice, it is inevitably plagued with micropores and cracks through which moisture and other contaminants can penetrate to the electro-optical material. To increase the sealing properties of such PET / ITO or similar front substrates, it is desirable to laminate a redundant barrier layer on the front substrate, the redundant barrier layer being a homopolymer (e.g., polychlorotrifluoroethylene available from Honeywell Corporation under the registered trademark "ACLAR") or a sputtered ceramic (e.g., AlO available from Toppan Printing Company under the trade name Toppan GX film) x) and is formed from. In other embodiments, flexible glass such as Corning's WILLOW (registered trademark) glass can be used. The redundant barrier layer should be thin, ideally about 12 μm, to provide a flexible display, but can be as thick as 5 mils (127 μm) if sufficient flexibility is still available. When an adhesive layer is required to attach the redundant barrier to the front substrate, the adhesive layer is transparent, colorless, thin, flexible, has low creep (when the display is bent or rotated), and should be durable at all temperatures within the operating range of the display. Certain cross-linked polyurethanes and polyacrylates can be used as such adhesives. Suitable optically clear adhesives are commercially available from Norland Adhesives.

[0074] Alternatively, the barrier properties of a PET / ITO or similar front substrate can be improved by coating either the surface of the front substrate opposite the ITO layer or directly beneath the ITO layer with a redundant metal oxide layer (e.g., an alumina or zinc oxide layer). The combination of the ITO layer and the redundant metal oxide layer improves the barrier properties of the front substrate (e.g., by reducing the migration of water vapor through inevitable cracks and micropores in the ITO layer) without accompanying more yellowing of the substrate than would occur if attempts were made to improve the barrier properties by increasing the thickness of the ITO layer. Instead of a simple metal oxide layer, more complex structures containing ceramic materials such as Barix (registered trademark) seal materials available from Vitex Systems, Inc. (3047 Orchard Parkway, San Jose, CA 95134) can be used, and again, the barrier layer can be provided either on the surface of the front substrate remote from the ITO layer or directly beneath the ITO layer. Vitex Systems currently sells a polymer film that supports both the Barix layer and the ITO layer under the trade name FlexGlass 200, but the polymer film is 5 mils (127 μm) PEN.

[0075] The barrier properties, flexibility, cost, and other properties such as other special properties of the front substrate may also be controlled by careful selection of both the polymer and the conductive material used in the front substrate. Almost any flexible and optically transmissive polymer may, in principle, be used, and suitable polymers include PET, PEN, polycarbonate, poly(vinylidene chloride) (sold under the registered trademark "SARAN"), polychlorotrifluoroethylene (sold under the registered trademarks "ACLAR" and "CLARIS"), triacetyl cellulose, materials sold under the registered trademark "ARTON" by JSR Company, polyethersulfone (PES), and laminates of two or more of these materials. Suitable transparent conductive materials include ITO, organic conductive polymers such as Baytron P (registered trademark), carbon nanotubes, and other suitably conductive optically transmissive conductors having a resistivity of less than about 10 4 ohms per square (transmittance greater than 60 percent).

[0076] Exemplary embodiments of a display according to the present invention will be described herein by way of illustration only with reference to the accompanying drawings. In all cases, the electro-optic layer may be any of a encapsulated electrophoretic layer, a polymer dispersed electrophoretic layer, or other types of electro-optic layers discussed above. The display may contain one or two laminated adhesive layers and the electro-optic material may be attached to the front substrate and / or the backplane. The display may be viewed through any of the laminated adhesive layers and the display may be assembled by directly coating and laminating, or by using front plane lamination, inverted front plane lamination, or double release film, as described in the patents and applications described in the "Cross References to Related Applications" section of this specification. As described above, the display is normally viewed through the front substrate, but in some cases, a light transmissive backplane may be used to provide a dual-sided display or one operating in the aforementioned masking mode. Such a structure may be used in a variable transmittance film, whereby the amount of light transmitted through the film can be electronically modified. In all of the accompanying drawings, the electro-optic display will hereinafter be illustrated with the viewing surface (alternatively referred to as the front surface) of the display at the top such that references to the front and back surfaces refer to the upper and lower surfaces, respectively, as illustrated in the associated drawings.

[0077] FIG. 1 of the accompanying drawings is a schematic cross-sectional cut-away view showing an exemplary embodiment of a sealed electro-optic display 100 according to the subject matter presented herein. In particular, FIG. 1 corresponds to cross-section A-A identified in FIG. 2D by cross-sectional plane cut line 205.

[0078] Electro-optical display 100 typically includes a top transparent electrode 110, a layer of electrophoretic medium 120, and a bottom electrode 130 having a plurality of pixel electrodes of an active matrix of pixels, often controlled by thin film transistors (TFTs). The electrophoretic medium 120 contains electrophoretic particles 121 and electrophoretic particles 122. The electrophoretic particles 121 and 122 may have different electric charges and different optical properties. For example, the electrophoretic particles 121 may be black and have a positive charge, while the electrophoretic particles 122 may be white and have a negative charge. However, in some embodiments, the electrophoretic medium 120 includes only a single type of electrophoretic particle or three or more electrophoretic particles each potentially having different optical, electro-optical, or chemical properties. The electrophoretic medium 120 typically includes a nonpolar solvent such as isoparaffin and may also include dispersed polymers and charge control agents to promote state stability, e.g., bistability, i.e., the ability to maintain an electro-optical state without input of any additional energy.

[0079] As shown in FIG. 1, the electrophoretic medium 120 is compartmentalized by a plurality of microcapsules 126. However, in some embodiments, the electrophoretic medium 120 is compartmentalized by the walls of a plurality of microcells (not shown in FIG. 1). The structure (also referred to as FPL125) formed from the top electrode 110 and the layer of electrophoretic medium 120 is typically disposed on a substrate 150, which may be rigid or flexible. In some embodiments, FPL125 is disposed on a backplane 155, which is an assembly including a bottom electrode 130 woven as a plurality of pixel electrodes, an array of thin film transistors (not shown in FIG. 1), and a substrate 150. It should be understood that in other embodiments, the bottom electrode 130 may be a single electrode such as a carbon paste electrode or a metal foil (not shown). Additionally, in some embodiments, the bottom electrode 130 is light transmissive and may be made of the same or a similar material as the top electrode 110.

[0080] The electro - optical display 100 typically also includes an upper protective or barrier layer 160 to protect the upper electrode 110 from damage and a bottom protective or barrier layer 161 to protect the substrate 150 from damage. The upper barrier layer 160 and the bottom barrier layer 161, together with the edge - seal components, which are discussed in detail below, may enclose the entire electro - optical display 100, prevent water ingress, and limit fluctuations in the relative humidity within the display. As shown in FIG. 1, the upper barrier layer 160 and the bottom barrier layer 161 can extend beyond the peripheries of the upper electrode 110 and the substrate 150.

[0081] The electro - optical display 100 can also include an adhesive layer 140 between the upper electrode 110 and the upper barrier layer 160 and an adhesive layer 141 between the substrate 150 and the bottom barrier layer 161. Although not shown in FIG. 1, the electro - optical display 100 can include one or more additional adhesive layers (e.g., between the upper electrode 110 and the layer of the electrophoretic medium 120, between the layer of the electrophoretic medium 120 and the backplane 155), if desired. In some embodiments, the adhesive layer can include an integrated primer component to improve adhesion, or a separate primer layer (not shown in FIG. 1) can be used. (The structure, pigments, adhesives, electrode materials, etc. of electrophoretic displays and component parts are described in many patents and patent applications published by, for example, E Ink Corporation, such as U.S. Pat. Nos. 6,922,276, 7,002,728, 7,072,095, 7,116,318, 7,715,088, and 7,839,564, all of which are incorporated herein by reference in their entirety.) In some embodiments, the barrier layer is processed to include an integrally - formed adhesive material or layer on at least one surface.

[0082] The electro-optical display 100 can also include an edge seal formed by a flexible barrier tape 170, which extends along the outer perimeter of the electro-optical display 100. As shown in FIG. 1, the adhesive layer 142 adheres the flexible barrier tape 170 to the upper barrier layer 160, and the adhesive layer 143 adheres the flexible barrier tape 170 to the bottom barrier layer 161. Although depicted in FIG. 1 as distinct layers, in some embodiments, the barrier tape 170 comprises an outer layer having good barrier properties and an integrated inner adhesive layer used to secure the barrier tape 170 to the upper and bottom barrier layers (160, 161) of the display.

[0083] In some embodiments, the barrier tape 170 has a thickness of about 12 μm, but can also be on the order of 0.005 inches (127 μm). The barrier tape 170 can be formed from a material having good barrier properties, including a polymer (e.g., a homopolymer such as polychlorotrifluoroethylene or a similar material) or a ceramic sputtered onto PET, PEN, PC, or other transparent plastic. Alternatively, if transparency is not required, a metal foil such as aluminum can be used. These materials are designed to be flexible to some extent, but can crack if bent or flexed at excessive angles. Thus, the electro-optical display 100 includes rods 180 positioned adjacent to the outer perimeter of the electro-optical display 100 and contacting the barrier tape 170 at its bending points. The bending radius of the barrier tape 170 is thus controlled based on the average diameter 185 and position of the rods 180, thereby minimizing or eliminating cracking of the barrier tape 170.

[0084] In some embodiments, rod 180 comprises nylon fibers and has an average diameter 185 of about 0.020 inches (0.508 mm). In some embodiments, rod 180 has an average diameter 185 of about 0.010 inches (0.254 mm) and about 0.100 inches (2.54 mm). One of ordinary skill in the art will understand that the average diameter 185 of rod 180 can be set according to the thickness of electro-optical display 100 and the desired bend radius of barrier tape 170. Rod 180 can be formed from materials such as fluorinated organic compounds (e.g., fluorocarbons or similar materials), polymers (e.g., nylon, ultra-high molecular weight polyethylene (UHMWPE), high modulus polyethylene (HMPE), polycarbonate, acrylic, polystyrene, or similar materials), and the like. In some embodiments, rod 180 is formed from fiberglass.

[0085] Figures 2A-2D are cutaway bottom views (e.g., as viewed from the side opposite the viewer shown in FIG. 1) illustrating steps of a method for manufacturing an electro-optical display with edge seal components, in accordance with the subject matter presented herein. FIG. 2A is a cutaway bottom view 200A illustrating edge seal components added to an electro-optical display. The electro-optical display shown in FIG. 2A is substantially identical to electro-optical display 100 described in connection with FIG. 1, except that no edge seal components (e.g., flexible barrier tape 170, rod 180, adhesive layer 142, and adhesive layer 143) have been applied yet.

[0086] The upper barrier layer 160 (not shown in FIG. 2A) and the bottom barrier layer 161 (and their corresponding adhesive layers if they are separate components) can be sized to extend from each edge of the electro-optical display by an amount substantially equal to the diameter of the rod component, such that they would be used to form each edge seal. In some embodiments, an extended sheet of the barrier layer material is applied to the top and bottom of the electro-optical display 100 and then subsequently cut to the desired size. In some embodiments, the upper barrier layer 160 and the bottom barrier layer 161 are pre-cut to a predetermined size prior to being applied to the electro-optical display 100. The adhesive layer 142 and the adhesive layer 143 are formulated and applied such that the upper and bottom barrier layers can be attached to the electro-optical display 100 without bonding the upper and bottom overhang portions of the barrier material together, but the adhesive is still sufficiently sticky to hold the rod component in place until they are permanently fixed in place by the barrier tape, as described in detail below.

[0087] As shown in FIG. 2A, the rod 181 is installed along the outer edge of the electro-optical display 100 between the overhang portions of the upper barrier layer 160 and the bottom barrier layer 161. Prior to being applied to the electro-optical display 100, the rod 181 can be pre-cut to a predetermined length based on the dimensions of the electro-optical display 100. Alternatively, the rod 181 can be cut to the desired length (e.g., substantially the same length as the upper barrier layer 160 and the bottom barrier layer 161) after being applied to the electro-optical display 100 (shown by the cut 291 and the dashed line in FIG. 2A).

[0088] The barrier tape 171 is then applied to the upper barrier layer 160 such that the midpoint 171c in the length direction of the barrier tape 171 is positioned adjacent to the outer edge of the rod 181. In some embodiments, the barrier tape 171 is applied to the upper barrier layer 160 such that the midpoint 171c in the length direction will be positioned substantially at or near the vertical midpoint of the rod 181 when the barrier tape 171 is subsequently applied to the bottom barrier layer 161. For example, refer to the position of the midpoint 170c in the length direction of the rod 180 in FIG. 1.

[0089] As shown by the arrow 290, the barrier tape 171 is then wound around the rod 181 while remaining in close contact with the rod 181 until the barrier tape 171 is applied to the bottom barrier layer 161. The rounded shape and diameter of the rod 181 prevent the barrier tape 171 from bending or cracking at a radius that could cause the barrier tape 171 to bend during or after application to the electro-optical display. A substantially similar process is used to install the rod 182 and apply the barrier tape 172 to the electro-optical display such that the midpoint 172c in the length direction will be positioned substantially at or near the vertical midpoint of the rod 182 when the barrier tape 172 is subsequently applied to the bottom barrier layer 161.

[0090] The barrier tapes described in the embodiments of this specification are applied first to the upper barrier layer 160 and then subsequently to the bottom barrier layer 161. Those skilled in the art will understand that a process in which the barrier tape is applied first to the bottom barrier layer 161 is also within the scope of the present disclosure.

[0091] Figure 2B is a cut-away bottom view 200B illustrating an electro-optical display to which barrier tapes 171 and 172 are applied. The portions of barrier tapes 171 and 172 that extend beyond the edges of upper barrier layer 160 and bottom barrier layer 161 can be cut off and removed, as shown by cut 292 and the dashed line in Figure 2B. In some embodiments, barrier tapes 171 and 172 are pre-cut to a predetermined length and applied based on the dimensions of electro-optical display 100 so that they do not require cutting.

[0092] Figure 2C is a cut-away bottom view 200C illustrating barrier tape 170 applied to an electro-optical display. In a process substantially similar to that described above, rod 180 is installed between upper barrier layer 160 and bottom barrier layer 161, and barrier tape 170 is first applied to upper barrier layer 160. However, prior to wrapping barrier tape 170 around rod 180, edge seal material 196 is applied to the corners of the electro-optical display. For example, a syringe 295 can be used to apply edge seal material 196 at the seams where rods 181 and 182 meet the individual ends of rod 180.

[0093] Edge seal material 196 can consist of dispensed sealant (heat, chemically, and / or radiation cured), polyisobutylene, or an acrylate-based sealant, among others. In some embodiments, curable edge seal material 196 is a UV-curable resin having a low water vapor transmission rate (WVTR). WVTR is a measure of the water vapor permeability of a given material, i.e., the mass of water vapor passing through a given area of the material at a defined temperature and humidity over a given period. In some embodiments, edge seal material 196 is a material having a WVTR of less than or equal to about 0.01 g / m 2 / day at 60°C and 100% relative humidity. In some embodiments, edge seal material 196 has a WVTR of about 0.01 to about 2 g / m at 60°C and 90% relative humidity. 2It is a material having a WVTR of 2 - 3 g / m² / day. At 60 °C and 90% relative humidity 2 Edge seal material 196 having a WVTR of 2 (e.g., UV500 manufactured by HumiSeal, UV A80 manufactured by Cemedine Co., Ltd.) has been found to be effective as a moisture barrier in some embodiments. Also, hybrid radiation and thermosetting sealants (i.e., UV curable using heat after firing) have been found to provide certain advantages in display system performance. For example, the Threebond 3000 / 3100 series materials (manufactured by Threebond Corporation (Cincinnati, OH)) have favorable water vapor barrier properties (e.g., low water vapor permeability), low viscosity at high temperatures for easy dispensing of the edge seal material, good wetting characteristics, and manageable curing properties. Those skilled in the art and those well-versed in advanced sealants will be able to identify other sealants that provide equivalent performance.

[0094] The curable edge seal material 196 is then cured using an ultraviolet irradiation device to create a moisture-proof seal at the corners of the electro-optical display 100 where rods 181 and 182 meet the ends of rod 180. As shown by arrow 292, the barrier tape 170 is then wound around rod 180 while remaining in close contact with rod 180 until the barrier tape 170 is applied to the bottom barrier layer 161 (and across the ends of barrier tapes 171 and 172). The rounded shape and diameter of rod 180 prevent the barrier tape 170 from bending or being bent at a radius that could crack the barrier tape 170 during or after application to the electro-optical display.

[0095] Finally, any portion of the barrier tape 170 that extends beyond the edges of the upper barrier layer 160 and the bottom barrier layer 161 can be cut and removed. In some embodiments, the barrier tape 170 is pre-cut to a predetermined length and applied based on the dimensions of the electro-optical display 100 so as not to require cutting. A substantially similar process can be used to add edge seals to other edges of the electro-optical display (not shown in FIG. 2C).

[0096] FIG. 2D is a cut-away bottom view 200D illustrating an electro-optical display (e.g., electro-optical display 100) incorporating an edge seal in accordance with the techniques and techniques described herein. As discussed above, the edge seal components and processing processes of the present invention minimize or eliminate cracking of the barrier tape material, thereby advantageously preventing moisture and contaminants from penetrating into the electro-optical materials and other components of the electro-optical display. Such edge seals are more difficult to scale up for high-volume production processes because the edge seal liquid must be dispensed around the perimeter of each electro-optical display and then cured, in addition to being more time-consuming and difficult to implement, and can provide performance equivalents or better than conventional liquid-dispensed edge seals. In contrast, using the edge seal techniques and techniques described herein allows many of the components to be pre-prepared and significantly reduces the curing time because only a small amount of curable edge seal material is used per electro-optical display.

[0097] Furthermore, the edge seal technology described herein reduces the width of the barrier material around the perimeter of a finished electro-optical display significantly compared to electro-optical displays that employ conventional clamped edge seals (e.g., FIGS. 2 of U.S. Pat. No. 7,649,674 and FIG. 4 of U.S. Patent Application Publication No. 2020 / 0032081) formed by sandwiching and bonding together overhanging top and bottom barrier layer materials. Conventional clamped edge seals can add a width of 15 mm or more to each edge of the electro-optical display. The outer boundary region or bezel portion of a housing for a display incorporating an electro-optical display produced using the edge seal technology described herein can thus be made significantly narrower than the bezel of a display incorporating an electro-optical display with conventional clamped edge seals. Thus, for a display housing of a given size, a display incorporating an electro-optical display using the edge seal technology of the invention described herein can have a larger visible area than a display incorporating a conventional clamped edge seal electro-optical display. The edge seal technology of the invention described herein also increases the scalability of display applications by enabling composite display structures to consist of several individual electro-optical displays arranged as closely as possible in a tiled configuration. For example, the reduced width of the perimeter barrier material enables individual electro-optical display segments to be positioned close enough to each other to give the composite display the appearance of a seamless, integral screen.

[0098] In an alternative embodiment, the continuous segment of the rod material is wound around the entire perimeter of the electro-optical display. The material used for the rod member is selected such that the rod member is not deformed or damaged by the bend radius required to route the rod member around each corner of the display. Further, a continuous piece of barrier tape is used to seal the edges of the display. This embodiment advantageously eliminates manufacturing steps such as sizing and cutting each segment of the rod member and the barrier tape individually. Also, since the barrier tape is a continuous length of material without voids or openings at the corners, the need for UV curable edge sealant material at each corner is eliminated.

[0099] FIG. 3 is a schematic cross-sectional view 300 of an adhesive barrier tape 370 with an integrated rod 380, according to the subject matter presented herein. The barrier tape 370 can be formed from a material substantially similar to the barrier tape described above and can include an adhesive layer 342 that coats at least one side of the tape and the integrated rod 380 that extends along the length of the barrier tape 370. The rod 380 can be positioned substantially along the longitudinal center of the barrier tape 370.

[0100] FIG. 4 is a schematic cross-sectional cutaway view showing an exemplary embodiment of a sealed electro-optical display 400 incorporating an adhesive barrier tape 370 with an integrated rod 380, according to the subject matter presented herein. The barrier tape 370 can be applied to the edge of the electro-optical display such that the integrated rod 380 is substantially directly adjacent to the edge of the electro-optical display 100. The barrier tape 370 can then be folded and cut to the size as described above or pre-cut to a desired length. A curable edge sealant material can be applied as described above to seal the corners of the electro-optical display 400.

[0101] The electro - optical display 400 provides all of the advantages of the electro - optical display 100 described above and offers further advantages in that the barrier tape 370 reduces the number of manufacturing steps required to produce the electro - optical display, particularly steps that typically must be performed manually. The speed of the manufacturing process is also significantly improved. For example, an entire sheet or roll of electro - optical display material can be coated with the top and bottom barrier layers in a single operation, and individual electro - optical displays of the desired dimensions can then be cut from the larger sheet. Thus, when using the barrier tape 370, after the electro - optical display is cut from the larger sheet, it is no longer necessary to apply the top and bottom barrier layers to the electro - optical display in a secondary operation and then cut an oversize sheet of barrier layer material so that they extend from each edge of the electro - optical display by an amount substantially equal to the diameter of the rod.

[0102] In an alternative embodiment, a continuous piece of the barrier tape 370 is wound around the perimeter of the entire perimeter of the electro - optical display. The material used for the rod members is selected such that the rod members are not deformed or damaged by the bend radii required to route the rod members around each corner of the display. This embodiment advantageously eliminates manufacturing steps such as sizing and cutting each section of the barrier tape individually. Also, since the barrier tape is a continuous length of material without voids or openings at the corners, it eliminates the need for UV - curable edge seal material at each corner.

[0103] Some electro - optical display applications may benefit from additional useful features apart from the better moisture - barrier properties of the edge - seal components described above. For example, variable - transmittance window films for architectural applications are often applied to the outer surface of existing glass windows to save significant time and money during installation. Such films are generally exposed to extreme temperature variations, moisture, and mechanical stress due to varying weather conditions.

[0104] A variable transmittance window film for architectural use can also be placed between glass plates inside the window during manufacture to better protect and insulate the film. However, the film can still be exposed to mechanical stresses imposed by building structures such as similar temperature variations, vibrations, and flexures. Further, the various materials used in variable transmittance window films, glass plates, window frames, and other structural components typically have significantly different properties from each other (e.g., coefficient of thermal expansion, modulus of elasticity, etc.) and thus can physically change (e.g., expand / contract, flex, twist, etc.) at different rates in response to changing environmental conditions.

[0105] Thus, the edge seal technology described herein can include additional features that provide the added durability and protection needed to make such applications feasible in more demanding environments. For example, in some embodiments, the inner surface of an edge seal barrier tape applied to the top and bottom barrier layers of an electro-optical display (e.g., top barrier layer 160 and bottom barrier layer 161) incorporates a layer of electrically insulating material.

[0106] The insulating material prevents the electrodes (e.g., top electrode 110 and bottom electrode 130) from shorting to each other and to other components within the structure or housing in which the electro-optical display 100 can be disposed. Further, the edge seal barrier tape described herein can protect the different layers of the electro-optical display 100 from delaminating at their edges during handling and final use disposition. Advantageously, this enables the electro-optical display 100 to be produced using a roll-to-roll process without requiring an additional lamination step to add a protective and / or barrier layer after cutting the component from a roll of finished display material. For example, conventional manufacturing techniques require that each portion of the display material cut from the roll be laminated piece by piece, which is a time-consuming process and likely to introduce defects into the display, particularly into the viewing area. In contrast, using the edge seal barrier tape described herein, a device manufacturer can simply cut pieces of the display film from the roll, apply electrical connections to the film electrodes as needed, and wrap the edges with the barrier tape in preparation for final disposition within a building structure or product housing.

[0107] In some embodiments, the barrier tape is processed as a multi-layer stack of materials having different properties based on the environmental conditions to which the barrier tape will be exposed. In some embodiments, the barrier tape includes a barrier material (e.g., a metal foil or similar material) on a surface that will be exposed to the outside environment and an insulating material (e.g., polyimide or similar material) on a surface that will be applied to a barrier layer of the electro-optical display. In some embodiments, the barrier tape is a PET film coated with ceramic. In some embodiments, the barrier tape is produced from a material having both barrier and insulating properties as a single multifunctional film.

[0108] Furthermore, the structures of the edge seal barrier tapes described herein can be modified according to the specific use of the finished electro-optical display. In some embodiments, the barrier tape is processed such that a first portion of its outer surface contains a first material and a second portion of its outer surface contains a second material having different properties from the first material. For example, referring to FIG. 1, the electro-optical display 100 can be a variable transmittance window film that would be applied to the outer surface of an existing glass window. The barrier tape 170 can be produced such that substantially half of its outer surface contains a first material and substantially half of its outer surface contains a second material having different properties from the first material. For example, the outer surface of the barrier tape 170 can be distributed longitudinally in substantially equal halves with an adhesive portion 170a on the first half and a barrier portion 170b on the second half. The adhesive portion 170a contains an adhesive or other bonding agent and can facilitate the application of the electro-optical display 100 to the window glass. The outward-facing barrier portion 170b is provided with a wear or weather-resistant material and can provide additional durability to the electro-optical display 100.

[0109] In some embodiments, the electro-optical display 100 is intended to be used as a stand-alone device and the entire outer surface of the barrier tape 170 is wear-resistant but does not contain an adhesive. In some embodiments, the barrier tape 170 comprises a colorant (e.g., a dye, pigment, or another substance used for coloring). In some embodiments, the barrier tape 170 is provided in any one of a variety of colors to enable color matching to an architectural structure or product housing on or in which the electro-optical display 100 is disposed.

[0110] FIG. 10 is a schematic cross-sectional view showing an exemplary embodiment of a variable transmittance window 1000 including a sealed electro-optical display stack according to the subject matter presented herein. The variable transmittance window 1000 typically includes an upper transparent electrode 1010, a layer of electrophoretic medium 1020, and a bottom transparent electrode 1030. The upper transparent electrode 1010 and the bottom transparent electrode 1030 are light-transmissive conductive layers, each of which can comprise a continuous planar layer of conductive material. Alternatively, one or both of the upper transparent electrode 1010 and the bottom transparent electrode 1030 can comprise a plurality of separately addressable pixel electrodes controlled by thin film transistors (TFTs).

[0111] The electrophoretic medium 1020 contains a plurality of electrophoretic particles 1021. The electrophoretic particles 1021 can have different electric charges and different optical properties. In some embodiments, the electrophoretic particles 1021 are black and have a positive charge. In some embodiments, the electrophoretic particles 1021 are white and have a negative charge. In some embodiments, the electrophoretic medium 1020 contains only a single type of electrophoretic particle or three or more electrophoretic particles, each of which can potentially have different optical, electro-optical, or chemical properties.

[0112] The electrophoretic medium 1020, shown in FIG. 10, is compartmentalized into a plurality of microcells by walls 1027. However, in some embodiments, the electrophoretic medium 1020 is compartmentalized by a plurality of microcapsules similar to the electro-optic display 100 of FIG. 1. A protruding structure 1028 is formed within each microcell. The protruding structure 1028 can have several geometric shapes. In this example, the protruding structure 1028 is a cone on a cylinder. The protruding structure 1028 has a protruding base, a protruding wall surface, a protruding top end, and a protruding height. The protruding top end is a point or set of points of the protruding structure 1028 that has a shorter distance from the microcell opening than any other point of the protruding structure 1028. In some embodiments, the walls 1027 and the protruding structure 1028 are formed from a polymeric material as discussed in the patents and publications referenced above.

[0113] In the example of the microcell of FIG. 10, the top end of the protruding structure 1028 is the top end of the cone. The protruding height is the distance between the protruding base and the protruding top end. If the protruding structure 1028 has a top end with a point above one such as a planar surface, the protruding height is the distance between the planar surface and the base of the protruding base.

[0114] The microcells are sealed by a seal layer 1012, which may be, for example, a UV-cured fluoropolymer. In some embodiments, the seal layer 1012 is a hydrophilic polymer that is incompatible with the fluid within the electrophoretic medium 1020. Examples of components used in the seal composition for the seal layer 1012 may include, but are not limited to, thermoplastic or thermosetting materials and their precursors. Specific examples may include materials such as monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, polyfunctional methacrylates, polyvinyl alcohol, polyacrylic acid, cellulose, gelatin, or equivalents. Additives such as polymer binders or thickeners, photoinitiators, catalysts, vulcanizing agents, fillers, colorants, or surfactants may be added to the seal composition to improve the physical mechanical properties and the light collimating film.

[0115] The seal composition may be a water-soluble polymer with water as a seal solvent. Examples of suitable water-soluble polymers or water-soluble polymer precursors include, but are not limited to, polyvinyl alcohol, polyethylene glycol, its copolymers with polypropylene glycol, and its derivatives, such as PEG-PPG-PEG, PPG-PEG, PPG-PEG-PPG, poly(vinyl pyrrolidone) and its copolymers, such as poly(vinyl pyrrolidone) / vinyl acetate (PVP / VA), polysaccharides, such as cellulose and its derivatives, poly(glucosamine), dextran, guar gum, and starch, gelatin, melamine-formaldehyde, poly(acrylic acid), its salt form, and its copolymers, poly(methacrylic acid), its salt form, and its copolymers, poly(maleic acid), its salt form, and its copolymers, poly(2-dimethylaminoethyl methacrylate), poly(2-ethyl-2-oxazoline), poly(2-vinyl pyridine), poly(allylamine), polyacrylamide, polyethyleneimine, polymethacrylamide, poly(sodium styrene sulfonate), cationic polymers functionalized with quaternary ammonium groups, such as poly(2-methacryloxyethyl trimethylammonium bromide), poly(allylamine hydrochloride). The seal material may also include a water-dispersible polymer with water as a formulation solvent. Examples of suitable polymer dispersants may include polyurethane dispersants and latex dispersants. Suitable latexes in the dispersant may include polyacrylate, polyvinyl acetate and its copolymers, such as ethylene vinyl acetate, and polystyrene copolymers, such as polystyrene butadiene and polystyrene / acrylate.

[0116] The variable transmittance window 1000 includes a protective or barrier layer 1060 to protect the top electrode 1010 from damage. An adhesive layer 1040, which is a first adhesive layer, is disposed between the top electrode 1010 and the barrier layer 1060. The barrier layer 1060, together with the edge seal components discussed in detail below, may enclose substantially the entire surface of the variable transmittance window 1000, prevent water ingress, and limit fluctuations in relative humidity within the structure of the variable transmittance window 1000.

[0117] Examples of additional components that may be present in the adhesive composition include, but are not limited to, acrylics, styrene-butadiene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyvinyl butyral, cellulose acetate butyrate, polyvinyl pyrrolidone, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, epoxides, polyfunctional acrylates, vinyls, vinyl ethers, and their oligomers, polymers, and copolymers. The adhesive layer may also contain polyurethane dispersants and water-soluble polymers selected from the group consisting of polyvinyl alcohol, its copolymers with polyethylene glycol and polypropylene glycol, poly(vinyl pyrrolidone) and its copolymers, polysaccharides, gelatin, poly(acrylic acid), its salt forms, and its copolymers, poly(methacrylic acid), its salt forms, and its copolymers, poly(2-dimethylaminoethyl methacrylate), poly(2-ethyl-2-oxazoline), poly(2-vinyl pyridine), poly(allylamine), polyacrylamide, polymethacrylamide, and cationic polymers functionalized with quaternary ammonium groups. The adhesive layer may be post-cured after lamination, for example, by radiation such as heat or UV.

[0118] In some embodiments, the adhesive layer can include an integrated primer component or a separate primer layer (not shown in FIG. 10) can be used to improve adhesion. (The structure of electrophoretic displays and component parts, pigments, adhesives, electrode materials, etc. are described in many patents and patent applications published by E Ink Corporation such as U.S. Pat. Nos. 6,922,276, 7,002,728, 7,072,095, 7,116,318, 7,715,088, and 7,839,564, all of which are incorporated herein by reference in their entirety.) In some embodiments, the barrier layer is processed to include an integral adhesive material or layer on at least one surface.

[0119] A display stack structure including a barrier layer 1060, an adhesive layer 1040, an upper transparent electrode 1010, a sealed microcell of electrophoretic medium 1020, and a bottom transparent electrode 1030 can be applied to a substrate 1050. An adhesive layer 1041, which is a second adhesive layer, adheres the display stack to the substrate 1050. In some embodiments, the display stack is laminated to the substrate 1050.

[0120] The substrate 1050 can be a material used to form a window glass plate. The substrate 1050 can be a certain type of glass, such as clear float glass, colored / tinted glass, solar glass (i.e., infrared absorbing / reflecting glass), self-cleaning glass (e.g., Pilkington Activ), low reflectivity glass (e.g., Pilkington Optiview), high-grade thin glass (e.g., Pilkington Microfloat), high optical purity glass (e.g., Pilkington Optiwhite), or a multi-layered structure formed from multiple types of glass materials. An example of solar glass is green glass that has a visible light transmittance of 75% (or more) and absorbs approximately 35% of infrared rays within the wavelength band of 0.9 to 1.3 microns. The substrate 1050 can also be any glass, polycarbonate, acrylic, or other suitable transparent sheet used to form a window glass plate.

[0121] The variable transmittance window 1000 can also include an edge seal formed by an edge seal material or a flexible barrier tape 1070, which extends along the outer periphery of the variable transmittance window 1000. The edge seal serves to prevent the ingress of moisture and other contaminants around the outer edge of the variable transmittance window 1000. As shown in FIG. 10, an adhesive layer 1042, which is a third adhesive layer, adheres the first horizontal section of the flexible barrier tape 1070 to a part of the upper portion of the barrier layer 1060, the vertical section of the flexible barrier tape 1070 to the outer vertical edge of the layer constituting the display stack, and the second horizontal section of the flexible barrier tape 1070 to the surface of the substrate 1050. Although depicted as distinct layers in FIG. 10, in some embodiments, the barrier tape 1070 comprises an outer layer having good barrier properties and an integrated inner adhesive layer used to secure the barrier tape 1070 to the layer constituting the display stack and the substrate 1050.

[0122] During operation, when an electric field is applied between the top transparent electrode 1010 and the bottom transparent electrode 1030 via a first voltage waveform, the electrophoretic particles 1021 that are electrically charged move towards the bottom transparent electrode 1030 and are directed towards the channels on both sides of the protruding structure 1028 by the inclination of the conical portion of the protruding structure 1028. The positioning of the electrophoretic particles 1021 within the channels results in the open or transparent state of the variable transmittance window 1000. The two leftmost microcells shown in FIG. 10 are exemplary embodiments of the positions of the electrophoretic particles 1021 when the variable transmittance window 1000 is in the open state.

[0123] To effect the transition from the open state to the opaque or closed state, the application of an electric field between the top transparent electrode 1010 and the bottom transparent electrode 1030 via a second voltage waveform causes the movement of the electrophoretically charged particles 1021 towards the top transparent electrode 1010 with a second velocity. The three rightmost microcells shown in FIG. 10 are exemplary embodiments of the positions of the electrophoretic particles 1021 when the variable transmittance window 1000 is in the closed or opaque state. In FIG. 10, showing the two leftmost microcells in the open state while simultaneously showing the three rightmost microcells in the closed state is merely illustrative of the pigment shielding mechanism. With respect to the variable transmittance window 1000 that includes a single top transparent electrode 1010 and a single bottom transparent electrode 1030, all of the microcells will typically be in the same state.

[0124] Also, it should be noted that when moving the electrophoretic particles 1021, it is necessary to impart a certain lateral velocity component. If not, they will simply move upward and vertically, but will not move laterally from their starting positions within the channel. In this scenario (no lateral direction), the closed state will virtually not be formed because the closed state would have a relatively high light transmittance. Induced-charge electroosmotic flow ("ICEO") can be used to provide such movement. For example, a fluid flow induced by the electrolyte movement around the electrophoretic particles 1021, which has a higher percentage of light transmittance in the closed optical state, results in the fluid being pulled towards the electrophoretic particles 1021 at the electrodes and being discharged at the equipotential circle. Other electrophoretic particles 1021 can also be entrained in the fluid, and since the electrophoretic particles 1021 can have different sizes, they can experience different magnitudes of ICEO velocities at an appropriate high applied field (typically, >1 V / micrometer) and low frequency (typically, in the range of 10 - 1,000 Hz AC). Thus, even if the particles are originally concentrated within one area, their random movement can be induced, resulting in the scrambling of their positions.

[0125] A variable transmittance window formed using the structure of the variable transmittance window 1000 can be manufactured at a lower cost than a display stack that includes barrier layers on the top and bottom. For example, such a variable transmittance window can be produced using fewer layers because a bottom barrier layer and a corresponding adhesive layer are not required, and a layer of laminated adhesive is not needed between the seal layer and the top transparent electrode. This also reduces the number of steps required to manufacture the display stack. Additionally, the omission of these layers makes such a variable transmittance window overall thinner and increases its light transmittance. Moreover, the product quality and manufacturing yield of the variable transmittance window 1000 are higher because the barrier layer 1060 can be applied to the display stack in a roll-to-roll manufacturing process, as opposed to being applied in a secondary lamination process after the display stack is adhered to the substrate 1050.

[0126] As discussed above, conventional dispensed thermosetting edge seals can take time to apply and cure around an electro-optical display. The edge seal barrier tape described above improves upon conventional dispensed edge seals, in part, by excluding the use of dispensed edge seal liquid, not entirely, but from the corners of the electro-optical display where adjacent barrier tape sections on adjacent display edges meet.

[0127] Figures 5A-5F illustrate additional aspects of the edge seal technology and related manufacturing techniques of the present invention described herein that completely eliminate the use of dispensed thermosetting barrier materials that require curing. In particular, a barrier seal is described that is formed from a flexible barrier material, positioned at each corner of an electro-optical display, and can seal the corners without using a curable edge seal material.

[0128] Figure 5A is a schematic 500a illustrating steps of a method for manufacturing a corner barrier seal 501 for an electro-optical display according to the subject matter presented herein. Figure 5A shows a top view of the corner barrier seal 501, i.e., a generally square-shaped sheet 501 of barrier material. The corner barrier seal 501 can be cut (shown by cut 591 and the dashed line in Figure 5A) to remove section 502, resulting in an X-shaped piece of barrier material.

[0129] In some embodiments, the corner barrier seal 501 is a metal foil formed from a ductile thin sheet metal such as annealed aluminum or tin. In some embodiments, the corner barrier seal 501 is coated or laminated with a plastic film to render it non-conductive and to protect the metal from mechanical damage. In some embodiments, the corner barrier seal 501 is formed from a material similar to the barrier tape or barrier layer described above.

[0130] In some embodiments, the corner barrier seal 501 is formed from a substantially square-shaped material, with sides each having a length of from about 5 mm to about 50 mm. In some embodiments, the corner barrier seal 501 is formed from a ceramic-coated PET having a net thickness, e.g., a thickness of from about 12 μm to about 127 μm. In some embodiments, the corner barrier seal 501 is formed from an aluminum foil-like material having a thickness of from about 6 μm to 50 μm, although thicker materials can also be used in combination with a metal forming tool capable of working with thicker metal materials.

[0131] The corner barrier seal 501 can be cut manually, by hand, or via a mechanized process such as an automated die or laser cutting. In some embodiments, a first cutting process is used to cut a square of the barrier material from a roll or a sheet of larger material, and a second, different cutting process is used to remove the section 502 from the corner barrier seal 501.

[0132] FIG. 5B is a schematic 500b illustrating additional steps of a method for manufacturing a corner barrier seal 501 for an electro-optical display according to the subject matter presented herein. FIG. 5B shows a top view of the corner barrier seal 501 in an X shape, where the section 502 has been removed here. The corner barrier seal 501 is folded or bent at each of the folds 503, 504a, and 504b (folds 504a and 504b, which are collectively referred to as "fold 504") and then unfolded back to its original shape. The folds 503 and 504 divide the upper surface of the corner barrier seal 501 into individual faces A - F that meet at the intersection 506.

[0133] FIG. 5C is a schematic view 500c showing the corner barrier seal 501 folded at the folding portion 503. As indicated by arrow 592, the folding portion 503 is a so-called "valley fold portion" which is made to be folded upward at the folding portion 503 until the side of the corner barrier seal 501 meets the upper surfaces of the upper surfaces of faces A, B, and C and the upper surfaces of faces D, E, and F. After the folding portion 503 is made, the corner barrier seal 501 is unfolded to its original shape.

[0134] FIG. 5D is a schematic view 500d showing the corner barrier seal 501 folded at the folding portion 504a. As indicated by arrow 593, the folding portion 504a is a so-called "mountain fold portion" which is made such that the corner barrier seal 501 is folded at the folding portion 504b until the bottom surfaces of faces B, C, and D meet the bottom surfaces of faces A, E, and F. After the folding portion 504a is made, the corner barrier seal 501 is unfolded to its original shape. Then, the folding portion 504b is made such that the corner barrier seal 501 is folded at the folding portion 504b until the bottom surfaces of faces A, B, and F meet the bottom surfaces of faces D, D, and E (not shown in FIG. 5D). After the folding portion 504b is made, the corner barrier seal 501 is unfolded again to its original shape.

[0135] The folding portions are described herein in a particular order, but one of ordinary skill in the art will understand that the folding portions 503, 504a, and 504b can be made in any order without altering the final configuration of the corner barrier seal 501.

[0136] The corner barrier seal 501 can be folded manually by hand or via a mechanized process such as a press die. In some embodiments, a combination of mechanized folding and hand folding is used to create the folding portions 503, 504a, and 504b.

[0137] FIG. 5E is an isometric schematic view 500e illustrating a corner barrier seal 501 for an electro-optical display after performing additional steps of a method for manufacturing according to the subject matter presented herein. As shown above, for each of the fold portions 503, 504a, and 504b of the corner barrier seal 501, after being fabricated, they are unfolded back to their original shape. To arrive at the configuration of the corner barrier seal 501 shown in FIG. 5E, the fold portions 503, 504a, and 504b are then refolded simultaneously along the same fold line to form two corner pockets, namely, a first corner pocket formed between surfaces A, B, and C, and a second corner pocket formed between surfaces D, E, and F.

[0138] Once the corner barrier seal 501 is prepared as described above, it can be applied to the corners of the electro-optical display. In one embodiment, the front plane laminate is first laminated to the backplane, and the resulting structure is cut to the desired display size. The corner barrier seal 501 can then be installed at each corner of the display. In some embodiments, each corner of the display laminate is folded into one of the two corner pockets of the corner barrier seal 501. In some embodiments, the inner surfaces of the corner barrier seal 501 (FIG. 5E, surfaces A, C, D, and F) can be folded or wedged between the front plane laminate and the backplane such that the corners of the front plane laminate are received within the corner pocket formed between surfaces A, B, and C, and the corners of the backplane are received within the corner pocket formed between surfaces D, E, and F.

[0139] Figure 5F is an isometric view 500F of the electro - optical display 500, where the corner barrier seal 501 is positioned at each corner. In some embodiments, the corner barrier seal 501 is covered by upper and bottom barrier layers that are subsequently laminated to the upper and bottom surfaces of the electro - optical display 500, so it does not require any adhesive to remain permanently in place. A tape - like edge seal, such as the flexible barrier tape described above, is then applied to each edge of the electro - optical display 500. Alternatively, the corner barrier seal 501 can still use a conventional clamped edge seal, for example, by sizing the upper and bottom barrier layers to extend beyond the edges of the display and the corner barrier seal 501 as required.

[0140] In some embodiments, the corner barrier seal 501 is produced with an adhesive on the bottom side of the barrier material so that the inner surface of the corner pocket can be adhered to the corner of the electro - optical display. This enables the corner barrier seal 501 to be applied to the corners of the electro - optical display after the lamination of the upper and bottom barrier layers, and a tape - like edge seal, such as the flexible barrier tape described above, can then be used to complete the edge - sealing process. This configuration can be advantageous for electro - optical displays that use ITO for the upper and bottom electrodes, which is common in architectural applications. For example, the upper and bottom barrier layers are laminated on the electro - optical display in a roll - to - roll manner, thereby minimizing the lamination steps per unit. The corner barrier seal 501 effectively seals the corners of the upper and bottom barrier layer surfaces without using a UV - curable resin with an adhesive, and the flexible barrier tape adheres to all surfaces of any exposed upper and bottom barrier layer material in addition to the corner barrier seal 501, forming an encompassing edge seal around the entire perimeter of the electro - optical display.

[0141] Accordingly, the corner barrier seal 501, described in connection with FIGS. 5A-5F, provides several advantages over conventional corner seal components and seal processes. For example, the corner barrier seal 501 enables a better moisture barrier seal to be formed at all points around the perimeter of an electro-optical display, reducing the required width of the barrier material at the edge of the finished electro-optical display, thereby leading to an increase in the active and viewing area of the electro-optical display compared to electro-optical displays that employ conventional clamped edge seals. Additionally, the corner barrier seal 501, which is fabricated from a ductile sheet metal such as annealed aluminum or tin, can be made thinner than the sputtered oxide type barrier films commonly used for conventional edge seals, but can be made more mechanically robust.

[0142] Incorporating the corner barrier seal 501 into the edge seal process for an electro-optical display also reduces the various materials and equipment required for the manufacturing process. For example, using the corner barrier seal 501 eliminates the need for materials and equipment associated with dispensing a thermosetting barrier material to the corners of the display, and similarly eliminates the need for a UV curing system. The corner edge seal 501 is also useful when the display is constructed in place (i.e., on-site), for example, when it is not possible to cut, wind, and cure the edge beads as described with respect to FIGS. 1-4 above.

[0143] Using the corner barrier seal 501 disclosed herein can also accelerate manufacturing time. For example, the corner barrier seal 501 can be formed separately from and prior to other components of the electro-optical display and can even be off-the-shelf components procured from a third party. The corner barrier seal 501 can thus be maintained in large quantities in the inventory of the manufacturing operation and can be an inventory part that is retrieved as needed during display production. Further, the corner barrier seal 501 enables easier scaling of the electro-optical display assembly operation because the manufacturing process, which can be in high demand and short supply at the manufacturing site, is not impeded by the use of special off-the-shelf components such as equipment at the UV curing station. This allows any number of assembly technicians to work in parallel at the manufacturing site and apply the corner barrier seal 501 to the electro-optical display in process.

[0144] Finally, similar to the barrier tape described above, the corner barrier seal 501 can be provided in any one of a variety of colors to make the corner piece less visually prominent. For example, a corner barrier seal fabricated from a metal foil can have a colored film or paint applied to one surface to more closely match the color of the product housing or building structure in which the electro-optical display is disposed.

[0145] In some embodiments, the section 502 is not removed from the corner barrier seal 501 as described in connection with FIG. 5A above. In this embodiment, the finished corner barrier seal 501 covers more of the active area of the display, but advantageously allows the barrier seal 501 to be fabricated from a simplified and more easily formed shape such as a square.

[0146] Other types of conventional edge seals can be formed by sandwiching and sealing an upper barrier layer to the surface of a backplane substrate. For example, to form an edge seal incorporated in FIG. 3 of U.S. Patent No. 7,649,674, summarized above, the peripheral portion of the barrier sheet that extends or "overhangs" from the outer edge of the display stack is "sandwiched" downwardly across other layers of the display and sealed to the peripheral portion of the backplane.

[0147] FIG. 6 is a schematic cross-sectional cutaway side view 600 showing a conventional sandwiched edge seal applied to an electro-optical display. In FIG. 6, an FPL 625 is laminated to a backplane 655, and the overhanging portion of the upper barrier layer 660 is adhered to the surface of the backplane 655 to form a sandwiched edge seal. Dimensions A - F identify the dimensions of an area of the electro-optical display associated with the sandwiched edge seal.

[0148] Dimension A typically refers to a portion of the electro-optical material that is set to black, remains unchanged during operation, and presents a distinct black border only around the perimeter of the display within the viewing area (e.g., directly adjacent to or overlapping the inner edge of the display bezel).

[0149] Dimension B indicates the width of the border portion of the FPL that remains unused or undriven during operation of the electro-optical display (e.g., no voltage is applied to change the optical state of the electro-optical medium within the area of dimension B). One reason for leaving this area unused is to account for any damage to the structure near the edge of the FPL that may have been received when cut from a larger sheet of material and / or any defects within the FPL at the edge of the larger sheet. For example, microcells within the electro-optical medium may be severed or incomplete at the edge, and this may also be the case for the walls surrounding the microcapsules. The combination of the areas shown by dimensions A and B may be referred to as the inactive area of the FPL since that area cannot be used to actively display an image.

[0150] The gap 662 is typically created between the upper barrier layer 660 and the surface 655 of the backplane when the clamped edge seal is applied. Dimension C identifies the width of the gap 662 at the surface of the backplane 655. Dimension D indicates the width of the portion of the upper barrier layer 660 that is adhered to the surface of the backplane 655. In some embodiments, a pressure-sensitive adhesive is used to adhere the upper barrier layer 660 to the surface of the backplane 655. Finally, dimension E indicates the width of the area at the surface of the backplane 655 between the end of the upper barrier layer 660 and the outer edge of the backplane 655.

[0151] Electro-optic displays incorporating these clamped edge seals typically have proper moisture diffusion protection on the surface of the display, but at the edges, it is relatively weak moisture diffusion protection. As described above in the discussion of conventional clamped edge seals, the area where the clamped portion of the barrier sheet is adhered to the surface of the backplane can be a moisture diffusion path at the edge of the electro-optic display. It has been observed that the pressure-sensitive adhesive used to adhere the upper barrier layer 660 to the surface 655 of the backplane can be a primary moisture diffusion path along the edge of the electro-optic display.

[0152] Means for reducing or mitigating the effects of edge moisture diffusion include increasing dimension A and / or dimension B, increasing the width of the inert area, and / or increasing the width of dimension D. These means effectively increase the distance and narrow the path that any moisture must travel in and out of the electro-optic display before it can adversely affect the performance of the area of the electro-optic display that is actively used to display the display image. The air within the gap 662 also provides a means of protection against moisture diffusion.

[0153] These means can improve the level of protection of the electro-optical display against moisture diffusion at its edges, but increasing any of the widths of the dimensions described above generally conflicts with the design goals and reduces the width of the bezel covering the portion of the display indicated by dimensions A - E and / or reduces the overall dimensions of the display housing.

[0154] The clamped edge seal of the present invention described below includes features that address the drawbacks of conventional clamped edge seals. In particular, the clamped edge seal and the corresponding process for its production are described, which includes a low WVTR UV curable resin that fills areas where voids (e.g., void 662) would otherwise be created during the formation of conventional clamped edge seals.

[0155] Figures 7A - 7E are schematic cross-sectional views 700A - 700E illustrating steps of a method for manufacturing an electro-optical display with an improved clamped edge seal according to the subject matter presented herein.

[0156] Figure 7A is a schematic cross-sectional view 700A illustrating steps of a method for manufacturing an electro-optical display with an improved clamped edge seal. In Figure 7A, an FPL 725 is laminated on a surface of a backplane 755 that substantially comprises a transparent substrate and electrodes. However, those skilled in the art will understand that electro-optical displays incorporating a backplane 755 formed from an opaque material are within the scope of the present disclosure.

[0157] Figure 7B is a schematic cross-sectional view 700B illustrating steps of a method for manufacturing an electro-optical display with an improved clamped edge seal. In Figure 7B, a dispenser 795 can be used to apply an edge seal material 796 around the perimeter of the FPL 725. In some embodiments, the dispenser 795 is a positive displacement fluid dispensing system that can adjust the pressure and speed at which the edge seal material 796 is dispensed to apply a consistent volume of the edge seal material 796 around the FPL 725.

[0158] In some embodiments, the edge seal material 796 is a material having a WVTR of less than about 0.0001 g / m 2 / day at 60° C. and 90% relative humidity. In some embodiments, the edge seal material 796 is a material having a WVTR of about 0.0001 to about 0.01 g / m 2 / day at 60° C. and 90-100% relative humidity. In some embodiments, the edge seal material 796 is a material having a WVTR of about 0.01 to about 2 g / m 2 / day at 60° C. and 90% relative humidity. In some embodiments, the edge seal material 796 having a WVTR of 2-3 g / m 2 / day at 60° C. and 90% relative humidity (e.g., UV500 made by HumiSeal, UV A80 made by Cemedine Co., Ltd.) has been found to be effective as a moisture barrier.

[0159] FIG. 7C is a schematic cross-sectional view 700C illustrating steps of a method for manufacturing an electro-optical display with an improved clamped edge seal. In FIG. 7C, an ultraviolet irradiation device or other curing system is used to partially cure the edge seal material 796 (shown by arrow 794) such that it is no longer free flowing but remains flexible and pliable. In some embodiments, the edge seal material 796 is cured over a period of about 25 seconds. In some embodiments, the edge seal material 796 is cured over a period of about 15-40 seconds. FIG. 7C shows that the curing is performed from both the top and bottom of the edge seal material 796, but the curing of the edge seal material 796 can be performed from the top and / or bottom provided that the backplane 755 is formed from a UV-transparent material.

[0160] Figure 7D is a schematic cross-sectional view 700D illustrating steps of a method for manufacturing an electro-optical display with an improved clamped edge seal. In Figure 7D, an upper barrier layer 760 is deposited over the FPL 725 and a partially cured edge seal material 796. The malleable edge seal material 796 flows sufficiently to fill spaces that would otherwise be voids (e.g., in Figure 6, void 662).

[0161] Figure 7E is a schematic cross-sectional view 700E illustrating steps of a method for manufacturing an electro-optical display with an improved clamped edge seal. In Figure 7E, an ultraviolet irradiation device or other curing system is used to fully cure the edge seal material 796 (indicated by arrow 794). In some embodiments, the edge seal material 796 is cured for more than 60 seconds. The clamped portion of the barrier layer 760 is also adhered to the surface 755 of the backplane. Figure 7E shows that the curing is performed from both the top and bottom of the edge seal material 796, but the curing of the edge seal material 796 can be performed from the top and / or bottom provided that the upper barrier layer 760 and the backplane 755 are formed from a UV-transparent material.

[0162] The upper barrier layer 760 shown in Figures 7D and 7E is depicted as a continuous layer of material. However, note that a process substantially similar to the process described in connection with Figures 7A-7E can be used to create an improved clamped edge seal using a barrier tape that is applied around the perimeter of the display stack after being deposited on a substrate. For example, the process can be used to form an improved clamped edge seal for the variable transmittance window 1000 described in connection with Figure 10.

[0163] Incorporating the improved clamped edge seal described herein reduces the impact of edge moisture diffusion and improves the overall moisture protection of the electro-optical display. Figures 8 and 9 are graphs illustrating the results of simulations run using a collated COMSOL moisture transport model for electro-optical displays incorporating conventional and improved clamped edge seals.

[0164] Figure 8 shows a graph 800 illustrating four plots of relative humidity in the electrophoretic medium as a function of distance from the edge of the FPL. The line plot 805ag plots the simulated edge moisture profile of an electro-optical display incorporating a conventional clamped edge seal with voids, operated for 5 days in an environment with an ambient temperature of 70 °C and a relative humidity of 23%. The line plot 805uv plots the simulated edge moisture profile of an electro-optical display incorporating an improved clamped edge seal, under the same environmental conditions over the same period. The line plot 810ag plots the simulated edge moisture profile of an electro-optical display incorporating a conventional clamped edge seal with voids, operated for 10 days in an environment with an ambient temperature of 70 °C and a relative humidity of 23%. The line plot 810uv plots the simulated edge moisture profile of an electro-optical display incorporating an improved clamped edge seal, under the same conditions over the same period.

[0165] As shown in Figure 8, the improved clamped edge seal is superior to the conventional edge seal for both 5- and 10-day periods, reducing the drop in relative humidity covered by the FPL near its edge. This results in more consistent electro-optical performance across the surface of the display. Additionally, it increases the durability of the display, particularly when the display is exposed to harsh conditions such as outdoors and undergoes large temperature variations (e.g., a display used for a bus stop timetable).

[0166] FIG. 9 shows a graph 900 illustrating four plots of relative humidity in an electrophoretic medium as a function of distance from the edge of the FPL. The line plot 905ag plots the simulated edge moisture profile of an electro-optical display incorporating a conventional clamped edge seal with voids, operated over 5 days in an environment with an ambient temperature of 70° C. and a relative humidity of 23%. For the line plot 905ag, dimension C (FIG. 6) is 1 mm and dimension D (FIG. 6) is 2.16 mm. The line plot 905uv plots the simulated edge moisture profile of an electro-optical display incorporating an improved clamped edge seal under the same environmental conditions over the same period. For the line plot 905uv, dimension C (FIG. 6) is also 1 mm, but dimension D (FIG. 6) is reduced to 1.5 mm.

[0167] Similarly, the line plot 910ag plots the simulated edge moisture profile of an electro-optical display incorporating a conventional clamped edge seal with voids, operated over 10 days in an environment with an ambient temperature of 70° C. and a relative humidity of 23%. For the line plot 910ag, dimension C (FIG. 6) is 1 mm and dimension D (FIG. 6) is 2.16 mm. The line plot 910uv plots the simulated edge moisture profile of an electro-optical display incorporating an improved clamped edge seal under the same environmental conditions over the same period. For the line plot 910uv, dimension C (FIG. 6) is also 1 mm, but dimension D (FIG. 6) is reduced to 1.5 mm.

[0168] The plots in FIG. 9 illustrate that an improved clamped edge seal design, which is superior to conventional air-gap edge seal designs even when dimension D is reduced, provides improved edge moisture diffusion performance. The outer boundary region or bezel portion of a display housing that incorporates an electro-optical display produced using the improved clamped edge seal technology described herein can, therefore, be made significantly narrower than the bezel of a display that incorporates an electro-optical display with a conventional clamped edge seal. Thus, for a display housing of a given size, a display that incorporates an electro-optical display with the improved clamped edge seal technology described herein can have a larger visible area or a smaller display housing than a display that incorporates a conventional clamped edge seal electro-optical display.

[0169] The improved clamped edge seal described herein includes features that provide improved protection against moisture diffusion at the display edge while maintaining or reducing the dimensions of the inactive and unused portions of the display at the edge. For example, the cured edge seal material 796 of the improved clamped edge seal forms a superior moisture barrier compared to the air present within a conventional clamped edge seal, thus allowing the dimensions of the inactive and / or unused portions of the edge of the display to be reduced. Further, the partial curing step of the related process of the present invention ensures that the UV-curable edge seal material 796 remains flexible prior to applying the upper barrier layer 760 over or between the layers of the FPL 725 without becoming viscous enough to exude above the layer of the FPL 725. This step also ensures that the edge seal material 796 does not dry so quickly as to form hard masses that are problematic for the UV resin higher than the FPL 725, or shrink to leave voids after curing. The partially cured edge seal material 796 can, therefore, conform to and fill the space that would normally be the void under the clamped edge seal.

[0170] The electrode arrays in the various types of displays of the present invention can be of either of the types described in the aforementioned E Ink and MIT patents and applications. Thus, for example, the display may be of the direct drive type, in which the backplane comprises a plurality of electrodes, each having a separate connector by means of which a controller can control the voltage applied to a particular electrode. In such a direct drive display, a single continuous front electrode is typically provided covering the entire display, although other front electrode arrays are also conceivable. Depending on the type of electro-optic material used, it may be conceivable to use a passive matrix drive arrangement in which (typically) the backplane carries a plurality of elongated parallel electrodes (“column electrodes”), while on the opposite side of the electro-optic material, a plurality of elongated parallel electrodes (“row electrodes”) are provided extending perpendicular to the column electrodes, and the overlap between one particular column electrode and one particular row electrode defines one pixel of the display. The display may also be of the active matrix type, typically with a single continuous front electrode covering the entire display and a matrix of pixel electrodes on the backplane, each pixel electrode defining one pixel of the display and having an associated transistor or other non-linear element, and the active matrix display is scanned in a conventional manner for writing to the display row by row. Finally, the display may also be of the stylus drive type, (typically) with a single electrode on the backplane, and writing to the display is effected by moving a stylus across the front surface of the display without a permanent front electrode.

[0171] The edge seals and sealing techniques of the present invention are mainly described in connection with electrophoretic displays, but those skilled in the art will understand that these edge seals and sealing techniques of the present invention are also very applicable to other electro-optical display technologies. Thus, for example, the present invention may be used to produce edge seals for use in combination with liquid crystal displays and organic light emitting diode (OLED) displays in, for example, e-book readers, portable computers, tablet computers, mobile phones, smart cards, signs, wristwatches, electronic shelf labels, and flash drives.

[0172] It will be apparent to those skilled in the art that numerous changes and modifications can be made to the specific embodiments of the invention described above without departing from the scope of the invention. Therefore, the foregoing description should be construed in an illustrative rather than a limiting sense.

Claims

【Claim 1】 The invention described in this specification.

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