Backplane for partitioned electro-optical displays and method for manufacturing the same

Abstract

A method for manufacturing a compartmentalized electro-optical display backplane includes: (a) providing a lamination comprising an insulating layer having opposing first and second surfaces and a conductive metal layer having opposing first and second surfaces (the second surface of the insulating layer is superimposed on the first surface of the conductive metal layer); (b) applying laser energy from a first laser source passing through the insulating layer onto a selected portion of the first surface of the conductive metal layer to thermally decompose adjacent portions of the insulating layer to form conductive carbon regions; and (c) applying laser energy from a second laser source onto the first surface of the insulating layer to thermally decompose a selected portion thereof into conductive carbon compartments electrically insulated from each other by the other portions of the insulating layer. The conductive carbon regions within the insulating layer form vias between each conductive carbon compartment and one of the selected portions of the conductive metal layer.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims priority to U.S. Provisional Patent Application No. 63 / 531,337, filed on August 8, 2023, and entitled "BACKPLANES FOR SEGMENTED ELECTRO - OPTIC DISPLAYS AND METHODS OF MANUFACTURING SAME", which is hereby incorporated by reference in its entirety.

[0002] This application relates to backplanes and manufacturing methods for segmented electro - optic displays. Such backplanes are intended, although not exclusively, for use in combination with displays comprising encapsulated electrophoretic media. The backplane can also be used in combination with various other types of electro - optic media that are "solid" in the sense of having a solid outer surface, although the media can have, and often do have, internal cavities containing a fluid (either a liquid or a gas). Such "solid electro - optic displays" include encapsulated electrophoretic displays, encapsulated liquid crystal displays, and other types of displays discussed below.

Background Art

[0003] An electro - optic display comprises a layer of electro - optic material, and the term is used herein, in its conventional meaning in the field of imaging technology, to refer to a material having at least first and second display states with at least one different optical property, 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, although this can 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 optical transmittance, reflectivity, luminescence, or machine reading.

[0004] The terms “bistable” and “bistability” are used herein to refer to a display having a display element having at least one first and second display state having different optical properties, where any given element is driven by a finite-duration electrical addressing pulse and exhibits either the first or second display state, and after the addressing pulse has terminated, that state will persist for at least several times, e.g., at least four times, the minimum duration of the addressing pulse required to change the state of the display element. U.S. Patent No. 7,170,670 shows that several particle-based electrophoretic displays capable of grayscale are stable not only in their extreme black and white state but also in their intermediate gray state, and the same is true for several other types of electro-optic displays. While this type of display is more appropriately called “multi-stable” rather than “bistable,” 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 the rotating bichromal member type, as described, for example, in U.S. Patents 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 bichromal ball" display, but in some of the patents mentioned above, the rotating member is not spherical, so the term "rotating bichromal member" is preferred as it is more accurate). Such displays use a number of small bodies (typically spherical or cylindrical) having two or more sections with different optical properties and an internal dipole. These bodies are suspended within vacuoles filled with a liquid in a matrix, and the vacuoles are filled with liquid so that the bodies can rotate freely. The appearance of the display is changed by applying an electric field to it, thereby rotating the bodies to various positions and changing the position of the body segments seen 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 comprising electrodes formed at least partially from a semiconductor metal oxide and a plurality of reversibly color-changing dye molecules attached to the electrodes (see, e.g., Nature (1991), 353, 737, by O'Regan, B., et al., and Information Display, 18(3), 24 (March 2002), by Wood, D.). See also Adv. Mater. (2002), 14(11), 845, by Bach, U., et al. This type of nanochromic film is also described, for example, in U.S. Patents 6,301,038, 6,870,657, and 6,950,220. This type of medium is also typically bistable.

[0007] Among these, particle-based electrophoretic displays, in which charged particles move through a suspension fluid under the influence of an electric field, are another type of electro-optical display. Such displays have been the subject of vigorous research and development for several years. Compared to liquid crystal displays, electrophoretic displays can possess attributes such as good brightness and contrast, wide viewing angles, state bistability, and low power consumption. Nevertheless, problems with the long-term image quality of these displays have hindered their widespread use. For example, the particles that make up electrophoretic displays can settle, potentially resulting in an insufficient lifespan for these displays.

[0008] As described above, electrophoretic media require the presence of a fluid. In most prior art electrophoretic media, this fluid is a liquid, but 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 WO 2004 / 090626, WO 2004 / 079442, and WO 2004 / 001498. Such gas-based electrophoretic media are considered susceptible to the same types of particle sedimentation problems as liquid-based electrophoretic media when used in orientations that allow for such sedimentation, for example, in a sign where the medium is positioned in a vertical plane. In fact, particle sedimentation is considered a more serious problem in gas-based electrophoretic media than in liquid-based media because the lower viscosity of gaseous suspension fluids compared to liquids allows for more rapid sedimentation of electrophoretic particles.

[0009] Numerous patents and applications, assigned to or filed in the names of the Massachusetts Institute of Technology (MIT) and E Ink Corporation, describe various techniques used in encapsulated electrophoretic media and other electro-optical media. Such encapsulated media comprise numerous small capsules, each comprising an internal phase containing electrophoretic mobile particles in a fluid medium, and a capsule wall surrounding the internal phase. Typically, the capsules themselves form a coherent layer, held within a polymer binder and positioned between two electrodes. The techniques described in these patents and applications include: (a) Electrophoretic particles, fluids, and fluid additives (see, for example, U.S. Patent Nos. 7,002,728 and 7,679,814) (b) Capsules, binders, and encapsulation processes (see, for example, U.S. Patent Nos. 6,922,276 and 7,411,719) (c) Microcell structures, wall materials, and methods for forming microcells (see, for example, U.S. Patent Nos. 7,072,095 and 9,279,906) (d) Methods for filling and sealing microcells (see, for example, U.S. Patent Nos. 7,144,942 and 7,715,088) (e) Films and subassemblies containing electro-optical materials (see, for example, U.S. Patent Nos. 6,982,178 and 7,839,564) (f) Backplanes, adhesive layers, other auxiliary layers, and methods used in displays (see, for example, U.S. Patents No. 7,116,318 and 7,535,624) (g) Color formation and color adjustment (e.g., U.S. Patent Nos. 6,017,584, 6,545,797, 6,664,944, 6,788,452, 6,864,875, 6,914,714, 6,972,893, 7,038,656, 7,038,670, 7,046,228, 7,052,571, 7,075,502, 7,167,155, 7,385,751, 7,492,505, 7,667,684) No. 7,684,108, No. 7,791,789, No. 7,800,813, No. 7,821,702, No. 7,839,564, No. 7,910,175, No. 7,952,790, No. 7,956,841, No. 7,982,941 No. 8,040,594, No. 8,054,526, No. 8,098,418, No. 8,159,636, No. 8,213,076, No. 8,363,299, No. 8,422,116, No. 8,441,714, No. 8,441,716 No. 8,466,852, No. 8,503,063, No. 8,576,470, No. 8,576,475, No. 8,593,721, No. 8,605,354, No. 8,649,084, No. 8,670,174, No. 8,704,756 No. 8,717,664, No. 8,786,935, No. 8,797,634, No. 8,810,899, No. 8,830,559, No. 8,873,129, No. 8,902,153, No. 8,902,491, No. 8,917,439 Nos. 8,964,282, 9,013,783, 9,116,412, 9,146,439, 9,164,207, 9,170,467, 9,170,468, 9,182,646, 9,195,111, 9,199,441, 9,268,191, 9,285,649, 9,293,511, 9,341,916, 9,360,733, 9,361,836, 9,383,623, and 9,423,U.S. Patent Application Publication No. 666, and U.S. Patent Application Publication Nos. 2008 / 0043318, 2008 / 0048970, 2009 / 0225398, 2010 / 0156780, 2011 / 0043543, 2012 / 0326957, 2013 / 0242378, 2013 / 0278995, 2014 / 0055840, 2014 / 0078576, 2014 / 0340430, 2014 / 0340736, and 2014 / 0362 See issues 213, 2015 / 0103394, 2015 / 0118390, 2015 / 0124345, 2015 / 0198858, 2015 / 0234250, 2015 / 0268531, 2015 / 0301246, 2016 / 0011484, 2016 / 0026062, 2016 / 0048054, 2016 / 0116816, 2016 / 0116818, and 2016 / 0140909). (h) Methods for driving a display (e.g., U.S. Patent Nos. 5,930,026, 6,445,489, 6,504,524, 6,512,354, 6,531,997, 6,753,999, 6,825,970, 6,900,851, 6,995,550, 7,012,600, 7,023,420, 7,034,783, 7,061,166, 7,061,662, 7,116,466, 7,119,772, 7,177,066, 7,193,625, 7,2 No. 02,847, No. 7,242,514, No. 7,259,744, No. 7,304,787, No. 7,312,794, No. 7,327 ,511, No. 7,408,699, No. 7,453,445, No. 7,492,339, No. 7,528,822, No. 7,545,3 No. 58, No. 7,583,251, No. 7,602,374, No. 7,612,760, No. 7,679,599, No. 7,679,813 No. 7,683,606, No. 7,688,297, No. 7,729,039, No. 7,733,311, No. 7,733,335, No. No. 7,787,169, No. 7,859,742, No. 7,952,557, No. 7,956,841, No. 7,982,479, No. 7, No. 999,787, No. 8,077,141, No. 8,125,501, No. 8,139,050, No. 8,174,490, No. 8,24 No. 3,013, No. 8,274,472, No. 8,289,250, No. 8,300,006, No. 8,305,341, No. 8,314, No. 784, No. 8,373,649, No. 8,384,658, No. 8,456,414, No. 8,462,102, No. 8,514,168 No. 8,537,105, No. 8,558,783, No. 8,558,785, No. 8,558,786, No. 8,558,855, No. 8,576,164, No. 8,576,259, No. 8,593,396, No. 8,605,032, No. 8,643,595, No. 8 ,665,206, No.8,681,191, No.8,730,153, No.8,810,525, No.8,928,562, No.8,9 No. 28,641, No. 8,976,444, No. 9,013,394, No. 9,019,197, No. 9,019,198, No. 9,019,Nos. 318, 9,082,352, 9,171,508, 9,218,773, 9,224,338, 9,224,342, 9,224,344, 9,230,492, 9,251,736, 9,262,973, 9,269,311, 9,299,294, 9,373,289, 9,390,066, 9,390,661, and 9,412,No. 314, and U.S. Patent Application Publications No. 2003 / 0102858, 2004 / 0246562, 2005 / 0253777, 2007 / 0091418, 2007 / 0103427, 2007 / 0176912, 2008 / 0024429, 2008 / 0024482, 2008 / 0136774, 2008 / 0291129, 2008 / 0303780, 2009 / 0174651, 2009 / 0195568, 2009 / 03 No. 22721, No. 2010 / 0194733, No. 2010 / 0194789, No. 2010 / 0220121, No. 2010 / 0265561, No. 2010 / 0283804, No. 2011 / 0063314, No. 2011 / 017587 No. 5, No. 2011 / 0193840, No. 2011 / 0193841, No. 2011 / 0199671, No. 2011 / 0221740, No. 2012 / 0001957, No. 2012 / 0098740, No. 2013 / 0063333, No. 2 No. 013 / 0194250, No. 2013 / 0249782, No. 2013 / 0321278, No. 2014 / 0009817, No. 2014 / 0085355, No. 2014 / 0204012, No. 2014 / 0218277, No. 2014 / No. 0240210, No. 2014 / 0240373, No. 2014 / 0253425, No. 2014 / 0292830, No. 2014 / 0293398, No. 2014 / 0333685, No. 2014 / 0340734, No. 2015 / 00707 See Nos. 44, 2015 / 0097877, 2015 / 0109283, 2015 / 0213749, 2015 / 0213765, 2015 / 0221257, 2015 / 0262255, 2015 / 0262551, 2016 / 0071465, 2016 / 0078820, 2016 / 0093253, 2016 / 0140910, and 2016 / 0180777 (these patents and applications may hereafter be referred to as MEDEOD ("Methods for Driving Electro-Optic Display") applications)). (i) Application of the display (see, for example, U.S. Patent Nos. 7,312,784 and 8,009,348) (j) Non-electrophoretic displays (see, for example, U.S. Patent No. 6,241,921 and U.S. Patent Application Publications 2015 / 0277160, 2015 / 0005720, and 2016 / 0012710)

[0010] Many of the aforementioned patents and applications recognize that the walls surrounding discrete microcapsules in encapsulated electrophoretic media can be replaced by a continuous phase, thus producing a so-called "polymer-dispersed electrophoretic display," in which the electrophoretic medium comprises a plurality of discrete droplets of electrophoretic fluid and a continuous phase of polymer material, and that discrete droplets of electrophoretic fluid in such a polymer-dispersed electrophoretic display can be considered as capsules or microcapsules even if the discrete capsule membrane is not associated with each individual droplet (see, for example, U.S. Patent No. 6,866,760). Therefore, for the purposes of this application, such polymer-dispersed electrophoretic media are considered a variant of encapsulated electrophoretic media.

[0011] A related type of electrophoretic display is the so-called microcell electrophoretic display. In a microcell electrophoretic display, charged particles and fluids are not encapsulated within microcapsules, but instead are held within a carrier medium, typically within a polymer film, in multiple cavities. See, for example, U.S. Patents 6,672,921 and 6,788,449.

[0012] Another type of electro-optical display is the electrowetting display, developed by Philips and described in Hayes, RA, et al.'s “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-optical materials can also be used in various embodiments. Of particular note is the bistable ferroelectric liquid crystal display (FLC), which is well known in the art.

[0014] Electrophoretic media are often impermeable (for example, in many electrophoretic media, the particles substantially block the transmission of visible light through the display) and operate in reflective mode. However, many electrophoretic displays can be manufactured to operate in a so-called "shutter mode," where one display state is substantially impermeable and the other is light-transmitting. See, for example, U.S. Patents 6,130,774 and 6,172,798, and U.S. Patents 5,872,552, 6,144,361, 6,271,823, 6,225,971, and 6,184,856. Dielectric displays, similar to electrophoretic displays but relying on variations in electric field intensity, can operate in a similar mode (see, for example, U.S. Patent 4,418,346).

[0015] Encapsulated or microcell electrophoretic displays typically do not suffer from the clustering and sedimentation failure modes of conventional electrophoretic devices and offer further advantages such as the ability to print or coat displays on a wide variety of flexible and rigid substrates. (The use of the word "printing" is intended to include, but is not limited to, all forms of printing and coating, including, patch die coating, slot or extrusion coating, slide or cascade coating, pre-metered coating such as curtain coating, roll coating such as knife over-roll coating, forward and reverse roll coating, gravure coating, immersion coating, spray coating, meniscus coating, spin coating, brush coating, air knife coating, silkscreen printing process, electrostatic printing process, thermal printing process, inkjet printing process, electrophoretic deposition, and other similar techniques). Therefore, the resulting display can be flexible. Furthermore, since the display medium can be printed (using various methods), the display itself can be manufactured inexpensively.

[0016] An electro-optic display typically comprises a layer of electro-optic material and at least two other layers positioned opposite the electro-optic material, one of which is an electrode layer. In most such displays, both layers are electrode layers, and one or both of the electrode layers are patterned to define pixels on the display. In most electro-optic displays, at least one of the electrode layers is light-transmitting. In passive matrix devices, one electrode layer may be patterned into extended row electrodes, while the other electrode layer may be patterned into extended column electrodes extending perpendicular to the row electrodes, with pixels defined by the intersections of the row and column electrodes. Alternatively, more commonly, one electrode layer may have the form of a single continuous (light-transmitting) electrode, while the other electrode layer may be patterned into a matrix of pixel electrodes, each defining one pixel on the display. In another type of electro-optic display intended for use with a separate stylus, print head, or similar movable electrode, only one of the layers adjacent to the electro-optic layer contains the electrode, and the layer on the opposite side of the electro-optic layer is typically a protective layer intended to prevent the movable electrode from damaging the electro-optic layer.

[0017] The manufacture of a three-layer electrophoretic display typically involves at least one lamination operation. For example, some of the aforementioned MIT and E INK patents and applications describe a process for manufacturing an encapsulated electrophoretic display, in which an encapsulated electrophoretic medium having capsules in a binder is coated onto a flexible substrate having an indium tin oxide (ITO) or similar conductive coating (acting as one electrode in the final display) on a plastic film (e.g., polyethylene terephthalate (PET)), and the capsule / binder coating is subsequently dried to form a coherent layer of electrophoretic medium that is firmly bonded to the substrate. Separately, a backplane is prepared containing an array of pixel electrodes and a suitable array of conductors for connecting the pixel electrodes to a driving network. To form the final display, a substrate having the capsule / binder layer thereon is laminated onto the backplane using a lamination adhesive. (A very similar process can be used to prepare electrophoretic displays that can be used 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 is flexible itself and is prepared by printing the pixel electrodes and conductors onto a plastic film or other flexible substrate. The lamination technique for mass production of displays by this process is roll-to-roll lamination using lamination adhesive. Similar manufacturing techniques can be used in combination with other types of electro-optical displays. For example, microcell electrophoretic media or rotating bicolor component media can be laminated onto the backplane in substantially the same manner as encapsulated electrophoretic media.

[0018] As discussed in the aforementioned U.S. Patent No. 6,982,178, many of the components used in solid-state electro-optical displays, and the methods used to manufacture such displays, are derived from the techniques used in liquid crystal displays (LCDs) (which are also electro-optical displays), but utilize a liquid medium. However, the methods used to assemble LCDs cannot be used in conjunction with solid-state electro-optical displays. LCDs are typically assembled by forming a backplane and a front electrode on separate glass substrates, then bonding these components together, leaving a small opening between them, placing the resulting assembly under vacuum, and immersing the assembly in a liquid crystal bath 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] A partitioned display includes an array of display segments that can be individually controlled to render a desired image. In a partitioned electro-optical display, the display segments can be formed within the backplane of the display and are selectively driven to alter the optical state of adjacent portions of the electro-optical medium.

[0020] Various embodiments disclosed herein relate to improved backplanes for compartmentalized electro-optical displays and methods for manufacturing such backplanes. The backplanes can be laminated onto a frontplane laminate containing an encapsulated electro-optical medium to produce compartmentalized electro-optical displays. [Prior art documents] [Patent Documents]

[0021] [Patent Document 1] U.S. Patent No. 7,170,670 [Overview of the Initiative] [Means for solving the problem]

[0022] A method according to an aspect of the present invention for manufacturing a backplane for a segmented electro-optical display is disclosed. The method includes: (a) providing a laminate comprising an insulating layer having opposing first and second surfaces and a conductive metal layer having opposing first and second surfaces, wherein the second surface of the insulating layer overlays the first surface of the conductive metal layer; (b) applying laser energy from a first laser source passing through the insulating layer onto selected portions of the first surface of the conductive metal layer to pyrolyze adjacent portions of the insulating layer and form conductive carbon regions; and (c) applying laser energy from a second laser source onto the first surface of the insulating layer to pyrolyze selected portions of the first surface of the insulating layer into a plurality of conductive carbon segments electrically insulated from each other by other portions of the insulating layer, wherein the conductive carbon regions in the insulating layer form vias between each of the plurality of conductive carbon segments and one of the selected portions of the conductive metal layer.

[0023] Disclosed is a backplane for a segmented electro-optical display, according to another aspect of the present invention. The backplane includes: (a) an insulating layer having opposing first and second surfaces; (b) a conductive metal layer having opposing first and second surfaces, wherein the second surface of the insulating layer overlaps on the first surface of the conductive metal layer; (c) a plurality of conductive carbon segments on the first surface of the insulating layer, electrically insulated from each other by a portion of the insulating layer, and formed by applying laser energy from a second laser source onto a selected portion of the first surface of the insulating layer; and (d) conductive carbon vias within the insulating layer that electrically connect each of the selected portions of the conductive metal layer to a different one of the conductive carbon segments, the conductive carbon vias being formed by applying laser energy from a first laser source different from the second laser source onto the first surface of the insulating layer, the laser energy from the first laser source passing through the insulating layer and reaching a selected portion of the first surface of the conductive metal layer, thermally decomposing an adjacent portion of the second surface of the insulating layer, and forming the conductive carbon vias.

[0024] According to one or more embodiments, the insulating layer comprises a polyimide layer, a polyethersulfone layer, or a polybenzimidazole layer.

[0025] According to one or more embodiments, the insulating layer comprises a Kapton® polyimide film.

[0026] According to one or more embodiments, the conductive metal layer comprises a copper layer, a silver layer, or an aluminum layer.

[0027] According to one or more embodiments, the conductive metal layer comprises a pattern of traces. [[ID=IPG=17]]

[0028] According to one or more embodiments, the second laser source comprises a CO2 laser.

[0029] According to one or more embodiments, the second laser source emits a laser beam having a wavelength of about 9 to 11 μm.

[0030] According to one or more embodiments, the first laser source comprises an Nd:YAG fiber laser.

[0031] According to one or more embodiments, the first laser source emits a laser beam having a wavelength of about 1 μm.

[0032] According to one or more embodiments, the insulating layer absorbs about 20% of the laser energy from the first laser source.

[0033] According to one or more embodiments, the insulating layer has a thickness of at least 12 μm.

[0034] According to one or more embodiments, the insulating layer has a thickness of about 12 μm to about 70 μm.

[0035] According to one or more embodiments, the conductive metal layer has a thickness of at least 9 μm. [Brief explanation of the drawing]

[0036] Additional details of one or more embodiments of the subject matter described herein are provided in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will also be apparent from the description and accompanying drawings contained herein. It should be noted that the accompanying drawings are schematic and not to scale. In particular, for ease of illustration, the thicknesses of various layers in the drawings do not correspond to their actual thicknesses. Similarly, the thicknesses of various layers are not to scale with respect to their lateral dimensions. In general, elements of similar structures are annotated throughout the drawings with similar reference numerals for illustrative purposes. However, the specific properties and functions of elements in different embodiments may not be identical. Furthermore, the drawings are intended merely to facilitate the description of the subject matter. The drawings do not illustrate all aspects of the embodiments described and do not limit the scope of this disclosure or the claims.

[0037] [Figure 1] Figure 1 is a schematic cross-sectional view showing an exemplary front-plane laminate according to prior art.

[0038] [Figure 2] Figure 2 is a schematic diagram showing an exemplary electro-optic device according to one or more embodiments.

[0039] [Figure 3] Figure 3 is a photograph showing an exemplary compartmentalized electro-optic device according to one or more embodiments.

[0040] [Figure 4] Figure 4 is a schematic cross-sectional view showing an exemplary backplane of a compartmentalized electro-optical device according to prior art.

[0041] [Figure 5] Figure 5 is a schematic cross-sectional view showing an exemplary backplane of a compartmentalized electro-optical device according to one or more embodiments.

[0042] [Figure 6] Figures 6A–6C schematically illustrate exemplary processes for forming a backplane of a compartmentalized electro-optic device according to one or more embodiments.

[0043] [Figure 7] Figure 7 is a schematic cross-sectional view showing an exemplary alternative backplane for a compartmentalized electro-optic device according to one or more embodiments.

[0044] [Figure 8] Figure 8 is a schematic cross-sectional view showing another exemplary backplane of a compartmentalized electro-optical device according to one or more embodiments.

[0045] [Figure 9] Figure 9 is a schematic diagram showing exemplary conductive trace patterns within the backplane of a compartmentalized electro-optic device according to one or more embodiments. [Modes for carrying out the invention]

[0046] Detailed explanation Various embodiments disclosed herein relate to backplanes with integrated barriers within a compartmentalized electro-optical display, and methods for manufacturing such backplanes. The backplane is laminated onto a frontplane laminate ("FPL") containing an encapsulated electro-optical medium to produce a compartmentalized electro-optical display.

[0047] The term "backplane," as used herein, is used in the art of electro-optical displays and in a manner consistent with its conventional meaning in the aforementioned patents and published applications, and refers to a rigid or flexible material comprising one or more electrodes within an electro-optical display. The backplane may also comprise electronic equipment for addressing the display, or such electronic equipment may be provided in a unit separate from the backplane. In flexible displays, it is desirable that the backplane provide sufficient barrier properties to prevent the ingress of moisture or other contaminants through the non-visible side of the display (the display is, of course, typically viewed from the side away from the backplane).

[0048] Figure 1 schematically shows an exemplary front-plane laminate (FPL) 100. As shown in Figure 2, the FPL 100 can be laminated on a backplane 112 according to one or more embodiments to produce an electro-optical display 114, for example, a partitioned electro-optical display. The FPL 100 is similar to that described in U.S. Patent No. 10,503,041, which is incorporated herein by reference. The FPL 100 includes, in order, a front-plane light-transmitting substrate 102, a light-transmitting conductive layer 104 in contact with the inner surface of the front-plane light-transmitting substrate 102, an electro-optical medium layer 106, an adhesive layer 108, and a release sheet 110. It should be understood that in other FPL embodiments, an additional layer of adhesive may be placed between the light-transmitting conductive layer 104 and the electro-optical medium layer 106 (not shown in Figure 1).

[0049] In many applications, the front-plane light-transmitting substrate 102 includes a PET layer, and the light-transmitting conductive layer 104 comprises indium tin oxide (ITO). Such materials are commercially available in large rolls, for example, from Saint-Gobain. The light-transmitting conductive layer 104 is applied to the light-transmitting substrate 102, which is typically flexible in the sense that the substrate can be manually wound around a drum with a diameter of, for example, 10 inches (254 mm), without permanent deformation.

[0050] The term “light-transmissive” is used herein in accordance with its conventional meaning in the art of electro-optical displays and in the aforementioned patents and published applications, by allowing sufficient light to pass through the layer, thereby enabling an observer looking through the layer to observe changes in the display state of the electro-optical medium that would normally be visible through the conductive layer 104 and the adjacent substrate 102. If the electro-optical medium 106 displays changes in reflectivity at invisible wavelengths, the term “light-transmissive” should naturally be interpreted to refer to the transmission of the relevant invisible wavelengths. The substrate 102 may be manufactured from glass or a polymer film, e.g., PET, and may have a thickness in the range of about 20 μm to about 650 μm, more typically about 50 μm to about 250 μm. The conductive layer 104 is typically a thin layer of a so-called "transparent conducting oxide," such as aluminum oxide, zinc oxide, indium zinc oxide, or indium tin oxide, or the conductive layer 104 may contain a conductive polymer such as poly(3,4-ethylenedioxythiophene) (PEDOT). The design may also include hybrid materials such as a combination of conductive polymers and conductive oxides, or the design may also include rare conductive fillers such as silver whiskers or flakes, or novel materials such as nanotubes and graphene. In some embodiments, the substrate 102 may be glass or a hard, light-transmitting material such as transparent polycarbonate or acrylic.

[0051] Typically, a coating of an electro-optic medium 106 that can be switched between optical states is applied across the conductive layer 104 such that the electro-optic medium 106 is in close proximity to the conductive layer 104. The electro-optic medium would typically feature an electrophoretic material containing a plurality of electrically charged particles that are placed in a fluid and are capable of moving through the fluid under the influence of an electric field. The electrophoretic material can be selected such that, when an appropriate electric field is applied, the front panel lamination achieves interchangeable and reversible different states, for example, the electrophoretic medium can switch between transparent and opaque, or between color 1 and color 2, or between transparent and color 1 and color 2.

[0052] In some embodiments, the electro-optic medium may be in the form of a reverse-charged double-particle encapsulated medium. Such an encapsulated medium comprises a number of small capsules, each of which comprises an inner phase containing electrophoretic mobile particles suspended in a liquid suspension medium, and a capsule wall surrounding the inner phase. Typically, the capsules are held within a polymer binder so that they themselves form a coherent layer. When the coherent layer is positioned between two electrodes, the optical state can be reversed with the presentation of a suitable electric field. The suspension medium may contain a hydrocarbon liquid suspended in negatively charged white particles and positively charged black particles. In such embodiments, in response to the application of an electric field across the electro-optic medium, the white particles move to the positive electrode and the black particles move to the negative electrode, thereby, for example, the electro-optic medium 106 appears white or black to an observer viewing the display through the substrate 102, depending on whether the conductive layer 104 is positive or negative with respect to the backplane at any point in the final display. The electro-optic medium 106 may, as an alternative, contain a plurality of colored particles in addition to black and / or white particles, each color having its own distinct charge properties and intensity. It should be understood that, although not shown in the drawings, the type of microcell-type FPL discussed above can also be used in conjunction with the backplane of the present invention.

[0053] A layer of laminated adhesive 108 is coated over the electro-optic medium layer 106, and a release sheet 110 is applied over the adhesive layer 108. The release sheet 110 can be any known type, provided that it does not contain any material that adversely affects the properties of the electro-optic medium. Numerous suitable types of release sheets will be known to those skilled in the art. Typical release sheets include a substrate such as paper or plastic film, e.g., PET film, which has a thickness of about 150 μm to about 200 μm and is coated with a low surface energy material, e.g., silicone. In some cases, the release sheet is metallized, allowing for the application of potential across the electro-optic medium, so that its functionality can be evaluated during the assembly of downstream products.

[0054] Now, looking at Figure 2, the electro-optical display 114 is assembled by removing the release sheet 110 on the FPL 100 and bringing the adhesive layer 108 into contact with the backplane 112 under conditions effective for bonding the adhesive layer 108 to the backplane 112, thereby fixing the adhesive layer 108, the electro-optical medium layer 106, and the light-transmitting conductive layer 104 to the backplane 112. The FPL 100 can be cut larger than the final display size and can also be a continuous sheet, as in a roll-to-roll process. This allows for coarse tolerances in the alignment of the FPL 100 and the backplane 112, which is particularly useful for large displays. Once laminated, the display can be cut to its final size, potentially allowing for precise alignment of the cut portion to the backplane using alignment marks or pins on the backplane.

[0055] The lamination of FPL100 onto the backplane 112 can be advantageously carried out by vacuum lamination. Vacuum lamination is effective in removing air from between the two materials being laminated, thus avoiding unwanted air bubbles in the final display, which can result in undesirable artifacts in the image produced on the display. However, vacuum lamination of two parts of the electro-optic display 114 in this manner can impose strict requirements on the lamination adhesive used, particularly in the case of displays using encapsulated electrophoretic media. The lamination adhesive 108 should have sufficient adhesive strength to bond the electro-optic layer 106 to the backplane 112, and in the case of encapsulated electrophoretic media, the adhesive 108 should also have sufficient adhesive strength to mechanically hold the capsules together. Preferably, the adhesive 108 is chemically compatible with all other materials in the display 114. If the electro-optic display 114 is of the flexible type, the adhesive 108 should have sufficient flexibility so as not to cause defects in the display when the display is bent. The lamination adhesive 108 should have a suitable fluidity at the lamination temperature to ensure high-quality lamination. Furthermore, the lamination temperature is preferably as low as possible. One example of a useful lamination adhesive that can be incorporated into various embodiments is an aqueous polyurethane dispersion known as a "TMXDI / PPO" dispersion, as described in U.S. Patent No. 7,342,068, which is incorporated as a whole by reference.

[0056] Figure 3 is a photograph showing one embodiment of a compartmentalized electro-optical device 114 according to one or more embodiments. The FPL 100 is stacked on a backplane 112. In this embodiment, an image is rendered on the device 114, which comprises an array of image elements 116 including a Christmas tree, a menorah, and letters. The image elements 116 correspond to and are aligned with similarly molded display sections formed within a compartmentalized conductive layer in the backplane 112, as discussed below.

[0057] Figure 4 is a schematic cross-sectional view showing an exemplary backplane 140 of a compartmentalized electro-optic device including a moisture barrier layer according to the prior art. The backplane 140 includes, in order, a conductive carbon upper layer 142, a PET insulating layer 144, an aluminum barrier layer 146, and an additional PET (protective) layer 148. The conductive carbon upper layer 142 is ablated using a fiber laser to form a plurality of display compartment shapes 149 connected to electrical trace connections within the upper layer. This type of backplane is primarily used in single-layer compartmentalized designs, i.e., both the display compartment shapes and electrical trace connections are in a single layer. However, multilayer designs in which the display compartment shapes and electrical trace connections are in separate layers would be preferable to single-layer designs because they have fewer design constraints. For example, traces would not need to be visibly routed between display compartments. In addition, display segments located distal to the edge connector of the device connected to the display controller can be connected by more conductive metal traces in a multilayer design that follows a more efficient path, rather than very long, less conductive carbon traces. However, fabricating this type of two-layer partitioned display backplane and separating the display segment shape from the electrical trace connections will usually require several additional steps to pattern and apply additional insulating and conductive layers.

[0058] Figure 5 is a schematic cross-sectional view showing an exemplary backplane 112 for a compartmentalized electro-optical device 114 according to one or more embodiments. The backplane 112 includes an insulating layer 150 and a conductive metal layer 152. A conductive carbon upper layer 154 comprising a plurality of display compartment shapes 156 is formed within the insulating layer 150. The display compartment shapes 156 are electrically insulated from each other. Vias 158 are formed within the insulating layer 150 to electrically connect each display compartment 156 to the conductive metal layer 152. The display compartment shapes 156 are therefore located in a separate layer from the electrical trace connections. As a result, traces are not visibly routed between the display compartments 156. In addition, the conductive metal layer 152 connects display compartments 156 located distal to the edge connector of the device connected to the display controller more efficiently than conductive carbon traces.

[0059] In one or more embodiments, the insulating layer 150 comprises a polyimide layer, preferably a Kapton® polyimide film available from DuPont de Nemours, Inc. The polyimide film preferably has a thickness of at least 12 μm. In one or more embodiments, the polyimide film has a thickness of about 12 μm to about 70 μm.

[0060] In other embodiments, the insulating layer 150 may comprise polyethersulfone, polybenzimidazole, and similar materials.

[0061] Figures 6A-6C schematically illustrate exemplary processes for manufacturing a backplane 112 of a compartmentalized electro-optical device 114 according to one or more embodiments.

[0062] As shown in Figure 6A, the backplane 112 is constructed from a lamination comprising an insulating layer 150 having opposing first and second surfaces 160, 162 and a conductive metal layer 152 having first and second surfaces 164, 166. The second surface 162 of the insulating layer 150 is superimposed on the first surface 164 of the conductive metal layer 152.

[0063] As shown in Figure 6B, laser energy is applied from the laser source 170 to a selected portion of the first surface 164 of the conductive metal layer 152 within a wavelength range that substantially passes through the insulating layer 150, causing the adjacent portion 172 of the insulating layer 150 to thermally decompose and form conductive carbon vias 158.

[0064] As shown in Figure 6C, laser energy from the second laser source 174 is applied to the first surface 160 of the insulating layer 150, thermally decomposing a selective portion of the first surface 160 of the insulating layer 150 into a plurality of conductive carbon compartments 156 that are electrically insulated from each other by the rest of the insulating layer 150. Vias 158 electrically connect each of the carbon compartments 156 to the conductive metal layer 152.

[0065] In one or more embodiments, the laser source 174 used to thermally decompose a portion of the insulating layer 150 to form conductive carbon compartments 156 comprises a CO2 laser. In one or more embodiments, the CO2 laser emits a laser beam having a wavelength of about 9–11 μm. The use of a CO2 laser to thermally decompose the insulating layer 150, in particular the Kapton® polyimide film, allows the insulating gap between the conductive carbon compartments 156 to be fabricated to be relatively small compared to other processes.

[0066] In one or more embodiments, the laser source 170 that forms vias 158 within the insulating layer 150 comprises a neodymium-doped yttrium aluminum garnet (Nd:YAG) fiber laser that emits light with a typical wavelength of about 1 μm (about 940 nm to about 1,440 nm).

[0067] The use of the fiber laser 170 allows vias to be formed from bottom to top, i.e., from the conductive metal layer 152 to the conductive carbon compartment 156. The insulating layer 150 is thought to be thermally decomposed by a combination of heating of the conductive metal layer 152 by the fiber laser 170 and reflection of the fiber laser beam back into the insulating layer 150 by the conductive metal layer 152, so that the focal point of the laser beam is within the insulating layer 150, thereby forming vias 158.

[0068] In addition to generating vias 158, the fiber laser 174 can also be used, if desired, to ablate or thermally decompose any other material on the back surface of the insulating layer 150.

[0069] Figure 7 is a schematic cross-sectional view showing an exemplary backplane 113 for a compartmentalized electro-optical device 114 according to one or more alternative embodiments. The backplane 113 includes an insulating layer (e.g., Kapton® polyimide film) 150 and a conductive metal (e.g., copper) layer 152. A conductive carbon upper layer 154, comprising a plurality of display compartment shapes 156, 157, is formed within the insulating layer 150. The display compartment shapes 156, 157 are electrically insulated from each other. Vias 158 are formed within the insulating layer 150 to electrically connect the display compartments 156 to the conductive metal layer 152. However, display compartments 157 do not have associated vias and are not electrically connected to the conductive metal layer 152. Display compartments 157 may include conductive carbon traces on the insulating layer 150 that lead to edge connectors (not shown), which can be connected to a display controller (not shown). In this way, the display controller can drive display sections 157 and 156 separately to achieve different optical states within the corresponding sections of the FPL 100. For example, in Figure 3, the display section that generates the Christmas tree image is connected to the edge connector by tracing, while other image elements are connected to the connector via the conductive metal layer 152. In this way, the Christmas tree can be rendered using a different color from the other image elements.

[0070] Figure 8 is a schematic cross-sectional view showing an exemplary backplane 200 for a compartmentalized electro-optical device 114 according to one or more alternative embodiments. The backplane 200 includes, in order, a conductive carbon top layer 154, an insulating layer (e.g., Kapton® polyimide film) 150, a conductive metal trace layer 201 (e.g., shown in Figure 9), a PET insulating layer 144, an aluminum barrier layer 146, and an additional protective PET layer 148. The conductive carbon top layer 154 comprises a plurality of display compartment shapes 156 formed within the insulating layer 150. The display compartment shapes 156 are electrically insulated from each other. Vias 158 are formed within the insulating layer 150 (e.g., using the process shown in Figures 6A-6C) to electrically connect each of the display compartments 156 to the conductive metal trace layer 201.

[0071] Figure 9 shows a simple embodiment of the conductive metal trace layer 201. The conductive metal trace layer 201 comprises a plurality of electrodes 202 (e.g., having copper, silver, or aluminum targets) that extend to the edge of the backplane 200 and are connected to a conductor 204 that extends to an electrical connector 206. The connector 206 can be connected to a display controller (not shown). The display controller can selectively control the voltage applied to the conductor 204 to individually drive each of the display sections 156 in order to change the optical state of adjacent corresponding portions of the electro-optic medium in the FPL 100. In this way, it is possible to display different colors for each display section.

[0072] The process described above simplifies the production of multilayer partitioned displays and enables the rapid formation of conductive carbon compartments 156 and vias 158 within a backplane 112 using two lasers that can reside in a single machine. In example, the process can be carried out using the Speedy Flexx® laser system available from Trotec Laser GmbH, which integrates CO2 and fiber laser sources into a single machine.

[0073] It will be apparent to those skilled in the art that numerous variations and modifications can be made in specific embodiments of the invention described above without departing from the scope of the present invention. Therefore, the entire preceding description should be interpreted in an illustrative rather than restrictive sense.

Claims

1. A method for manufacturing a backplane for a partitioned electro-optical display, wherein the method is To provide a laminate comprising an insulating layer having opposing first and second surfaces, and a conductive metal layer having opposing first and second surfaces, wherein the second surface of the insulating layer is superimposed on the first surface of the conductive metal layer, Laser energy from a first laser source passing through the insulating layer is applied to a selected portion of the first surface of the conductive metal layer, causing thermal decomposition of adjacent portions of the insulating layer to form a conductive carbon region. The method involves applying laser energy from a second laser source onto the first surface of the insulating layer, and thermally decomposing a selected portion of the first surface of the insulating layer into a plurality of conductive carbon compartments electrically insulated from each other by the other portions of the insulating layer, wherein the conductive carbon regions within the insulating layer form vias between each of the plurality of conductive carbon compartments and the conductive metal layer. Methods that include...

2. The method according to claim 1, further comprising applying laser energy from the second laser source to thermally decompose one or more additional selected portions of the first surface of the insulating layer into at least one additional conductive carbon portion that is electrically insulated from the plurality of conductive carbon portions and from the conductive metal layer, wherein the at least one additional conductive carbon portion includes a trace.

3. The method according to any one of claims 1 to 2, wherein the insulating layer comprises a polyimide layer, a polyethersulfone layer, or a polybenzimidazole layer.

4. The method according to any one of claims 1 to 3, wherein the insulating layer comprises a Kapton® polyimide film.

5. The method according to any one of claims 1 to 4, wherein the conductive metal layer comprises a copper layer, a silver layer, or an aluminum layer.

6. The method according to any one of claims 1 to 5, wherein the conductive metal layer has a trace pattern.

7. The second laser source is CO ２ The method according to any one of claims 1 to 6, comprising a laser.

8. The method according to any one of claims 1 to 7, wherein the second laser source emits a laser beam having a wavelength of about 9 to 11 μm.

9. The method according to any one of claims 1 to 8, wherein the first laser source comprises an Nd:YAG fiber laser.

10. The method according to any one of claims 1 to 9, wherein the first laser source emits a laser beam having a wavelength of about 1 μm.

11. The method according to any one of claims 1 to 10, wherein the insulating layer absorbs about 20% of the laser energy from the first laser source.

12. The method according to any one of claims 1 to 11, wherein the insulating layer has a thickness of at least 12 μm.

13. The method according to any one of claims 1 to 12, wherein the insulating layer has a thickness of about 12 μm to about 70 μm.

14. The method according to any one of claims 1 to 13, wherein the conductive metal layer has a thickness of at least 9 μm.

15. The method according to any one of claims 1 to 14, wherein the backplane is configured to be fixed to a frontplane laminate comprising a light-transmitting conductive layer and a layer of encapsulated electro-optic medium in electrical contact with the conductive layer, and the layer of encapsulated electro-optic medium is adapted to be superimposed on the first surface of the insulating layer of the backplane on the conductive carbon compartment.

16. A backplane for a partitioned electro-optical display, wherein the backplane is An insulating layer having opposing first and second surfaces, A conductive metal layer having opposing first and second surfaces, wherein the second surface of the insulating layer is superimposed on the first surface of the conductive metal layer, A plurality of conductive carbon compartments on the first surface of the insulating layer, wherein the plurality of conductive carbon compartments are electrically insulated from each other by a portion of the insulating layer, and are formed by applying laser energy from a second laser source onto a selected portion of the first surface of the insulating layer, Conductive carbon vias in the insulating layer that electrically connect each selected portion of the conductive metal layer to one of the different conductive carbon compartments, wherein the conductive carbon vias are formed by applying laser energy from a first laser source different from the second laser source onto the first surface of the insulating layer, the laser energy from the first laser source passing through the insulating layer to reach the selected portion of the first surface of the conductive metal layer, and thermally decomposing an adjacent portion of the second surface of the insulating layer to form the conductive carbon vias and A backplane equipped with this feature.

17. The backplane according to claim 16, further comprising at least one additional conductive carbon compartment electrically insulated from the plurality of conductive carbon compartments and from the conductive metal layer, wherein the at least one additional conductive carbon compartment is formed by applying laser energy from the second laser source and thermally decomposing one or more selected portions of the first surface of the insulating layer, and the at least one additional conductive carbon compartment includes a trace.

18. The backplane according to any one of claims 1 to 17, wherein the insulating layer comprises a polyimide layer, a polyethersulfone layer, or a polybenzoimidazole layer.

19. The backplane according to any one of claims 1 to 18, wherein the insulating layer comprises a Kapton® polyimide film.

20. The backplane according to any one of claims 1 to 19, wherein the conductive metal layer comprises a copper layer, a silver layer, or an aluminum layer.

21. The backplane according to any one of claims 1 to 20, wherein the conductive metal layer has a trace pattern.

22. The second laser source is CO ２ A backplane according to any one of claims 1 to 21, comprising a laser.

23. The backplane according to any one of claims 1 to 22, wherein the second laser source emits a laser beam having a wavelength of about 9 to 11 μm.

24. The backplane according to any one of claims 1 to 23, wherein the first laser source comprises an Nd:YAG fiber laser.

25. The first laser source emits a laser beam having a wavelength of about 1 μm, according to any one of claims 1 to 24.

26. The backplane according to any one of claims 1 to 25, wherein the insulating layer absorbs about 20% of the laser energy from the first laser source.

27. The backplane according to any one of claims 1 to 26, wherein the insulating layer has a thickness of at least 12 μm.

28. The backplane according to any one of claims 1 to 27, wherein the insulating layer has a thickness of about 12 μm to about 70 μm.

29. The backplane according to any one of claims 1 to 28, wherein the conductive metal layer has a thickness of at least 9 μm.

30. The backplane according to any one of claims 1 to 29, wherein the backplane is configured to be fixed to a frontplane laminate comprising a light-transmitting conductive layer and a layer of encapsulated electro-optic medium that is in electrical contact with the conductive layer, and the layer of encapsulated electro-optic medium is adapted to be superimposed on the first surface of the insulating layer of the backplane on the conductive carbon compartment.

31. An electro-optical display, wherein the electro-optical display comprises a backplane according to any one of claims 1 to 30, which is fixed to a frontplane laminate.

32. The electro-optical display according to claim 31, wherein the front plane laminate comprises a light-transmitting conductive layer and a layer of encapsulated electro-optic medium disposed between the light-transmitting conductive layer and the back plane.

33. The electro-optical display according to claim 31 or claim 32, wherein the electro-optical display is flexible.

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