Electrophoretic display with a thin edge seal

Abstract

Electrophoretic display modules are described that include various types of backplanes and edge seals to protect the electro-optic display against environmental contaminants. In particular, the disclosed module designs allow for very narrow edge seals, i.e., less than 1 mm thick. In one type of seal, the electro-optic layer is sandwiched between the backplane and a protective sheet, and a seal material extends between the backplane and the protective sheet. In some cases, the protective sheet includes several layers of transparent material to provide physical protection and reduce water ingress.

Description

Technical Field

[0001] (Reference to Related Applications) This application claims priority to U.S. Provisional Patent Application No. 63 / 187,972, filed May 13, 2021, and U.S. Provisional Patent Application No. 63 / 175,935, filed Apr. 16, 2021. The entire contents of all patents and published documents described below are hereby incorporated by reference in their entirety into this specification.

[0002] The present invention relates to an electrophoretic display having an edge seal. The present invention also provides a process for the production of such electrophoretic displays.

Background Art

[0003] The terms "bistable" and "bistability" are used herein in their conventional meaning in the art to refer to a display having display elements with first and second display states having at least one different optical characteristic, such that after any given element is driven using an address pulse of finite duration to exhibit either its first or second display state, after the address pulse has ended, the state of the display element will persist for at least several times, e.g., at least four times, the minimum duration of the address pulse required to change its state. In U.S. Patent No. 7,170,670, it has been shown that some particle-based electrophoretic displays with grayscale capability are stable not only in their extreme black and white states but also in their intermediate gray states, and the same is true for several other types of electro-optic displays. This type of display is appropriately referred to as "multi-stable" rather than "bistable", but for convenience, the term "bistable" may be used herein to include both bistable and multi-stable displays.

[0004] Numerous patents and applications assigned to or in the name of the Massachusetts Institute of Technology (MIT), E Ink Corporation, E Ink California, LLC, and related companies describe various technologies used in encapsulated and microcell electrophoretic media, and other electro-optic media. Encapsulated electrophoretic media include a number of small capsules, each of which itself includes an internal phase containing particles movable by electrophoresis in a fluid medium, and a capsule wall surrounding the internal phase. Typically, the capsules are themselves held within a polymeric binder to form a coherent layer positioned between two electrodes. In a microcell electrophoretic display, the charged particles and fluid are not encapsulated within microcapsules, but instead are held within a plurality of cavities formed within a carrier medium (typically, a polymeric film). [[Hereinafter, the term "microcavity electrophoretic display" may be used to include both encapsulated displays and microcell electrophoretic displays.]] The technology described in these patents and applications includes the following:

[0005] (a) Electrophoretic particles, fluid, and fluid additives: For example, U.S. Patent Nos. 5,961,804 (Patent Document 1), 6,017,584, 6,120,588, 6,120,839, 6,262,706, 6,262,833, 6,300,932, 6,323,989, 6,377,387, 6,515,649, 6,538,801, 6,580,545, 6,652,075, 6,693,620, 6,721,083, 6,727,881, 6,822,782, 6,831,771, 6,870,661, 6,927,892, 6,956,690, 6,958,849, 7,002,728, 7,038,655, 7,052,766, 7,110,162, 7,113,323, 7,141,688, 7,142,351, 7,170,670, 7,180,649, 7,226,550, 7,230,750, 7,230,751, 7,236,290, 7,247,379, 7,277,218, 7,286,279, 7,312,916, 7,375,875, 7,382,514, 7,390,901, 7,411,720, 7,473,782, 7,532,388, 7,532,389, 7,572,394, 7,576,904, 7,580,180, 7,679,814, 7,746,544, 7,767,112, 7,848,006, 7,903,319, 7,951,938, 8,018,640, 8,115,729, 8,199,395, 8,257,614, 8,270,064, 8,305,341, 8,361,620, 8,363,306, 8,390,918, 8,582,196, 8,593,718, 8,654,436, 8,902,491, 8,961,831, 9,052,564, 9,114,663, 9,158,174, 9,341,915, 9,348,193, 9,361,836, 9,366,935, 9,372,380, 9,382,427, 9,423,666, 9,428,649, 9,No. 552,780, No. 9,557,623, No. 9,664,978, No. 9,670,367, No. 9,671,667, No. 9,688,859, No. 9,726,957, No. 9,732,231, No. 9,752,034, No. 9,765,015, No. 9,778,535, No. 9,778,537, No. 9,778,538, No. 9,835,926, No. 9,864,253, No. 9,953,588, No. 9,995,987, No. 10,025,157, No. 10,031,394, No. 10,040,954, No. 10,061,123, No. 10,062,337, No. 10,431,168, No. 10,444,590, and No. 10,514,583, and U.S. Patent Application Publication Nos. 2003 / 0048522, 2003 / 0151029, 2003 / 0164480, 2004 / 0030125, 2005 / 0012980, 2009 / 0009852, 2009 / 0206499, 2009 / 0225398, 2010 / 0148385, 2011 / 0217639, 2012 / 0049125, 2013 / 0161565, 2013 / 0193385, 2013 / 0244149, 2014 / 0011913, 2014 / 0078024, 2014 / 0078573, 2014 / 0078576, 2014 / 0104674, 2014 / 0231728, 2015 / 0177590, 2015 / 0185509, 2015 / 0241754, 2015 / 0301425, and 2016 / 0170106;

[0006] (b) Capsules, Binders, and Encapsulation Processes: See, for example, U.S. Patent Nos. 5,930,026 (Patent Document 2), 6,067,185, 6,130,774, 6,172,798, 6,249,271, 6,327,072, 6,392,785, 6,392,786, 6,459,418, 6,839,158, 6,866,760, 6,922,276, 6,958,848, 6,987,603, 7,061,663, 7,071,913, 7,079,305, 7,109,968, 7,110,164, 7,184,197, 7,202,991, 7,242,513, 7,304,634, 7,339,715, 7,391,555, 7,411,719, 7,477,444, 7,561,324, 7,848,007, 7,910,175, 7,952,790, 7,955,532, 8,035,886, 8,129,655, 8,446,664, and 9,005,494, and U.S. Patent Application Publication Nos. 2005 / 0156340, 2007 / 0091417, 2008 / 0130092, 2009 / 0122389, and 2011 / 0286081;

[0007] (c) Microcell Structure, Wall Material, and Method of Forming Microcells: See, for example, U.S. Patent Nos. 6,672,921, 6,751,007, 6,753,067, 6,781,745, 6,788,452, 6,795,229, 6,806,995, 6,829,078, 6,833,177, 6,850,355, 6,865,012, 6,870,662, 6,885,495, 6,906,779, 6,930,818, 6,933,098, 6,947,202, 6,987,605, 7,046,228, 7,072,095, 7,079,303, 7,141,279, 7,156,945, 7,205,355, 7,233,429, 7,261,920, 7,271,947, 7,304,780, 7,307,778, 7,327,346, 7,347,957, 7,470,386, 7,504,050, 7,580,180, 7,715,087, 7,767,126, 7,880,958, 8,002,948, 8,154,790, 8,169,690, 8,441,432, 8,582,197, 8,891,156, 9,279,906, 9,291,872, 9,388,307, 9,436,057, 9,436,058, 9,470,917, 9,919,553, and 10,401,668, and U.S. Patent Application Publication Nos. 2003 / 0175480, 2003 / 0175481, 2003 / 0179437, 2003 / 0203101, 2014 / 0050814, and 2016 / 0059442;

[0008] (d) Method of filling and sealing a microcell: See, for example, U.S. Patent Nos. 6,545,797, 6,751,008, 6,788,449, 6,831,770, 6,833,943, 6,859,302, 6,867,898, 6,914,714, 6,972,893, 7,005,468, 7,046,228, 7,052,571, 7,144,942, 7,166,182, 7,374,634, 7,385,751, 7,408,696, 7,522,332, 7,557,981, 7,560,004, 7,564,614, 7,572,491, 7,616,374, 7,684,108, 7,715,087, 7,715,088, 8,179,589, 8,361,356, 8,520,292, 8,625,188, 8,830,561, 9,081,250, 9,346,987, and 9,759,978, and U.S. Patent Application Publication Nos. 2002 / 0188053, 2004 / 0120024, 2004 / 0219306, and 2015 / 0098124;

[0009] (e) Films and subassemblies containing electro-optical materials: See, for example, U.S. Patent Nos. 6,825,829, 6,982,178, 7,112,114, 7,158,282, 7,236,292, 7,443,571, 7,513,813, 7,561,324, 7,636,191, 7,649,666, 7,728,811, 7,729,039, 7,791,782, 7,826,129, 7,839,564, 7,843,621, 7,843,624, 8,034,209, 8,068,272, 8,077,381, 8,177,942, 8,390,301, 8,482,835, 8,786,929, 8,830,553, 8,854,721, 9,075,280, 9,238,340, 9,470,950, 9,554,495, 9,563,099, 9,733,540, 9,778,536, 9,835,925, 10,444,591, and 10,466,564, and U.S. Patent Application Publication Nos. 2007 / 0237962, 2009 / 0168067, and 2011 / 0164301;

[0010] (f) Backplane, adhesive layer, and other auxiliary layers, and methods used within a display: for example, U.S. Patent Nos. D485,294, 6,124,851, 6,130,773, 6,177,921, 6,232,950, 6,252,564, 6,312,304, 6,312,971, 6,376,828, 6,392,786, 6,413,790, 6,422,687, 6,445,374, 6,480,182, 6,498,114, 6,506,438, 6,518,949, 6,521,489, 6,535,197, 6,545,291, 6,639,578, 6,657,772, 6,664,944, 6,680,725, 6,683,333, 6,724,519, 6,750,473, 6,816,147, 6,819,471, 6,825,068, 6,831,769, 6,842,167, 6,842,279, 6,842,657, 6,865,010, 6,873,452, 6,909,532, 6,967,640, 6,980,196, 7,012,735, 7,030,412, 7,075,703, 7,106,296, 7,110,163, 7,116,318, 7,148,128, 7,167,155, 7,173,752, 7,176,880, 7,190,008, 7,206,119, 7,223,672, 7,230,751, 7,256,766, 7,259,744, 7,280,094, 7,301,693, 7,304,780, 7,327,346, 7,327,511, 7,347,957, 7,349,148, 7,352,353, 7,365,394, 7,365,733, 7,382,363, 7,388,572, 7,401,758, 7,442,587, 7,492,497, 7,535,624, 7,551,346, 7,554,712, 7,560,004, 7,583,427, 7,598,173, 7,605,799, 7,636,191, 7,649,No. 674, No. 7,667,886, No. 7,672,040, No. 7,688,497, No. 7,733,335, No. 7,785,988, No. 7,830,592, No. 7,839,564, No. 7,843,626, No. 7,859,637, No. 7,880,958, No. 7,893,435, No. 7,898,717, No. 7,905,977, No. 7,957,053, No. 7,986,450, No. 8,009,344, No. 8,027,081, No. 8,049,947, No. 8,072,675, No. 8,077,141, No. 8,089,453, No. 8,120,836, No. 8,159,636, No. 8,208,193, No. 8,237,892, No. 8,238,021, No. 8,362,488, No. 8,373,211, No. 8,389,381, No. 8,395,836, No. 8,437,069, No. 8,441,414, No. 8,456,589, No. 8,498,042, No. 8,514,168, No. 8,547,628, No. 8,576,162, No. 8,610,988, No. 8,714,780, No. 8,728,266, No. 8,743,077, No. 8,754,859, No. 8,797,258, No. 8,797,633, No. 8,797,636, No. 8,830,560, No. 8,891,155, No. 8,969,886, No. 9,147,364, No. 9,025,234, No. 9,025,238, No. 9,030,374, No. 9,140,952, No. 9,152,003, No. 9,152,004, No. 9,201,279, No. 9,223,164, No. 9,285,648, No. 9,310,661, No. 9,419,024, No. 9,454,057, No. 9,529,240, No. 9,620,066, No. 9,632,373, No. 9,632,389, No. 9,666,142, No. 9,671,635, No. 9,715,155, No. 9,777,201, No. 9,778,500, No. 9,841,653, No. 9,897,891, No. 9,910,337, No. 9,921,422, No. 9,964,831, No. 10,036,930, No. 10,037,735, No. 10,048,563, No. 10,048,564, No. 10,190,743, No. 10,324,577, No. 10,365,533, No. 10,No. 372,008, No. 10,429,715, No. 10,446,585, No. 10,466,564, No. 10,466,565, No. 10,495,940, No. 10,495,941, No. 10,503,041, and No. 10,509,294, and U.S. Patent Application Publication Nos. 2002 / 0060321, 2004 / 0085619, 2004 / 0105036, 2005 / 0122306, 2005 / 0122563, 2006 / 0255322, 2007 / 0052757, 2009 / 0122389, 2009 / 0315044, 2010 / 0177396, 2011 / 0140744, 2011 / 0187683, 2011 / 0292319, 2014 / 0078024, 2014 / 0192000, 2014 / 0210701, 2014 / 0368753, 2015 / 0378235, and 2016 / 0077375, and International Application Publication No. WO 00 / 38000, European Patent Nos. 1,099,207 B1, and 1,145,072 B1;

[0011] (g) Color formation and color adjustment: For example, 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, 7,684,108, 7,791,789, 7,800,813, 7,821,702, 7,839,564, 7,910,175, 7,952,790, 7,956,841, 7,982,941, 8,040,594, 8,054,526, 8,098,418, 8,159,636, 8,213,076, 8,363,299, 8,422,116, 8,441,714, 8,441,716, 8,466,852, 8,503,063, 8,576,470, 8,576,475, 8,593,721, 8,605,354, 8,649,084, 8,670,174, 8,704,756, 8,717,664, 8,786,935, 8,797,634, 8,810,899, 8,830,559, 8,873,129, 8,902,153, 8,902,491, 8,917,439, 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, 9,423,666, 9,436,056, 9,459,510, 9,513,527, 9,541,814, 9,552,780, 9,640,119, 9,646,547, 9,671,668, 9,697,778, 9,726,959, 9,740,076, 9,759,Nos. 9,810,981, 9,761,181, 9,778,538, 9,779,670, 9,779,671, 9,812,073, 9,829,764, 9,921,451, 9,922,603, 9,989,829, 10,032,419, 10,036,929, 10,036,931, 10,332,435, 10,339,876, 10,353,266, 10,366,647, 10,372,010, 10,380,931, 10,380,955, 10,431,168, 10,444,592, 10,467,984, 10,475,399, 10,509,293, and 10,514,583, 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, 2015 / 0103394, 2015 / 0118390, 2015 / 0124345, 2015 / 0268531, 2015 / 0301246, 2016 / 0026062, 2016 / 0048054, and 2016 / 0116818;

[0012] (h) Method of driving a display: For example, 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, 7,202,847, 7,242,514, 7,259,744, 7,304,787, 7,312,794, 7,327,511, 7,408,699, 7,453,445, 7,492,339, 7,528,822, 7,545,358, 7,583,251, 7,602,374, 7,612,760, 7,679,599, 7,679,813, 7,683,606, 7,688,297, 7,729,039, 7,733,311, 7,733,335, 7,787,169, 7,859,742, 7,952,557, 7,956,841, 7,982,479, 7,999,787, 8,077,141, 8,125,501, 8,139,050, 8,174,490, 8,243,013, 8,274,472, 8,289,250, 8,300,006, 8,305,341, 8,314,784, 8,373,649, 8,384,658, 8,456,414, 8,462,102, 8,514,168, 8,537,105, 8,558,783, 8,558,785, 8,558,786, 8,558,855, 8,576,164, 8,576,259, 8,593,396, 8,605,032, 8,643,595, 8,665,206, 8,681,191, 8,730,153, 8,810,525, 8,928,562, 8,928,641, 8,976,444, 9,013,394, 9,019,197, 9,019,198, 9,019,318, 9,Nos. 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, 9,412,314, 9,424,800, 9,460,666, 9,495,918, 9,501,981, 9,513,743, 9,514,667, 9,530,363, 9,542,895, 9,564,088, 9,612,502, 9,620,048, 9,620,067, 9,672,766, 9,721,495, 9,779,670, 9,881,564, 9,881,565, 9,886,886, 9,928,810, 9,966,018, 9,996,195, 10,002,575, 10,037,089, 10,380,954, 10,388,233, 10,475,396, and 10,504,Nos. 457, and U.S. Patent Application Publication Nos. 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 / 0322721, 2010 / 0194733, 2010 / 0194789, 2010 / 0220121, 2010 / 0265561, 2011 / 0063314, 2011 / 0175875, 2011 / 0193840, 2011 / 0193841, 2011 / 0199671, 2011 / 0221740, 2012 / 0001957, 2012 / 0098740, 2013 / 0063333, 2013 / 0194250, 2013 / 0249782, 2014 / 0009817, 2014 / 0085355, 2014 / 0204012, 2014 / 0218277, 2014 / 0240210, 2014 / 0253425, 2014 / 0293398, 2015 / 0262255, 2015 / 0262551, 2016 / 0071465, 2016 / 0093253, 2016 / 0140910, and 2016 / 0180777;

[0013] (i) Application to displays: For example, see U.S. Pat. Nos. 6,118,426, 6,473,072, 6,704,133, 6,710,540, 6,738,050, 6,825,829, 7,030,854, 7,119,759, 7,312,784, 7,705,824, 8,009,348, 8,011,592, 8,064,962, 8,162,212, 8,553,012, 8,973,837, 9,188,829, 9,197,704, 9,506,243, 9,880,646, and 10,331,005, and U.S. Patent Application Publication Nos. 2002 / 0090980, 2004 / 0119681, 2007 / 0285385, 2013 / 0176288, 2013 / 0221112, 2013 / 0233930, 2013 / 0235536, 2014 / 0049808, 2014 / 0062391, 2014 / 0206292, and 2016 / 0035291, and International Application Publication No. WO 00 / 36560.

[0014] Many of the aforementioned patents and applications recognize that the walls surrounding the separate microcapsules in an encapsulated electrophoretic medium can be replaced with a continuous phase, thus giving rise to a so-called "polymer-dispersed electrophoretic display," in which the electrophoretic medium comprises a plurality of separate droplets of an electrophoretic fluid and a continuous phase of a polymer material, and that the separate droplets of the electrophoretic fluid within such a polymer-dispersed electrophoretic display can be regarded as capsules or microcapsules even if no separate capsule membranes are associated with each individual droplet (see, e.g., U.S. Pat. No. 6,866,760). Thus, for the purposes of the present application, such a polymer-dispersed electrophoretic medium is regarded as a subclass of the encapsulated electrophoretic medium.

[0015] Electrophoretic media are often opaque (e.g., in many electrophoretic media, the particles substantially prevent the transmission of visible light through the display) and 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, e.g., U.S. Pat. Nos. 5,872,552, 6,130,774, 6,144,361, 6,172,798, 6,271,823, 6,225,971, and 6,184,856). Dielectrophoretic displays, which, like electrophoretic displays, rely on variations in electric field strength, can operate in a similar mode (see U.S. Pat. No. 4,418,346). Other types of electro-optic displays may also be capable of operating in a shutter mode. Electro-optic media that operate in a shutter mode can be useful in multilayer structures for full-color displays, in which at least one layer adjacent to the viewing surface of the display operates in a shutter mode to expose or conceal a second layer that is more remote from the viewing surface.

[0016] Encapsulated electrophoretic displays typically do not suffer from the clustering and sedimentation failure modes of conventional electrophoretic devices and offer additional advantages such as the ability to print or coat displays 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 process, electrostatic printing process, thermal printing process, inkjet printing process, electrophoretic deposition (see U.S. Patent No. 7,339,715), and other similar techniques.) As a result, the resulting display can be flexible. Further, since the display medium can be printed (using a variety of methods), the display itself can be manufactured at low cost.

[0017] A related type of electrophoretic display is the so-called "microcell electrophoretic display". In a microcell electrophoretic display, charged particles and a suspension fluid are not encapsulated within microcapsules but are instead held within a plurality of cavities formed within a carrier medium, typically a polymeric film (see, for example, International Application Publication No. WO 02 / 01281 and Published U.S. Application No. 2002 / 0075556, assigned to Sipix Imaging, Inc.).

[0018] An electro-optical device typically comprises a layer of electrophoretic material and at least two other layers disposed on opposite sides of the electrophoretic material, one of these two layers being an electrode layer. In most such displays, both of the 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 elongated row electrodes and the other into elongated column electrodes running perpendicular to the row electrodes, and the pixels are 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 electrophoretic display intended for use with a stylus, printing head, or similar movable electrode separate from the display, only one of the layers adjacent to the electrophoretic layer comprises electrodes, and the layer on the opposite side of the electrophoretic layer is typically a protective layer intended to prevent damage to the electrophoretic layer by the movable electrode.

[0019] 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, an encapsulated electrophoretic medium having capsules within a binder is coated onto a flexible substrate having an indium tin oxide (ITO) or 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. A process for manufacturing an encapsulated electrophoretic display is described. Separately, a backplane is prepared that includes an array of pixel electrodes and a suitable arrangement of conductors for connecting the pixel electrodes to a drive circuitry network. 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 a stylus or similar movable electrode and a usable electrophoretic display by replacing the backplane with a simple protective layer such as a plastic film on which the stylus or other movable electrode can slide). In one preferred form of such a process, the backplane itself is flexible and is prepared by printing the pixel electrodes and conductors onto a plastic film or other flexible substrate. An obvious lamination technique for mass - production of displays by this process is roll lamination using a lamination adhesive.

[0020] 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, this co-pending application describes a so-called "front plane laminate" ("FPL") which, in turn, comprises a light-transmissive conductive layer, a layer of 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 supported 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 is normally visible through the conductive layer and an adjacent substrate (if present). The substrate is typically a polymeric 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 conveniently be, for example, a thin metal layer of aluminum or ITO, or a conductive polymer. Poly(ethylene terephthalate) (PET) film coated with aluminum or ITO is commercially available, for example, from E.I. du Pont de Nemours & Company (Wilmington DE) as "aluminized Mylar" (where "Mylar" is a registered trademark), and such commercially available materials can be used with good results in front plane laminates.

[0021] The term "impulse" is used herein in its conventional meaning of the integral of voltage with respect to time. However, some bistable electro-optic media function as charge transducers, and for such media, an alternative definition of impulse, namely the integral of current over time (equal to the total charge applied), may be used. The appropriate definition of impulse should be used depending on whether the media functions as a voltage-time impulse transducer or as a charge impulse transducer. The term "waveform" will be used to denote the entire curve of voltage versus time used to effect a transition from a particular initial gray level to a particular final gray level. Typically, such a waveform comprises a plurality of waveform elements, and if these elements are essentially rectangular (i.e., if a given element comprises the application of a constant voltage over a period of time), the elements may be referred to as "pulses" or "drive pulses". The term "drive scheme" denotes a set of waveforms sufficient to effect all possible transitions between gray levels for a particular display. A display may utilize two or more drive schemes. For example, the aforementioned U.S. Patent No. 7,012,600 teaches that the drive scheme may need to be modified depending on parameters such as the temperature of the display or the time it has been operating during its lifetime, and thus, a plurality of different drive schemes may be provided for use of the display at different temperatures, etc. The set of drive schemes used in this manner may be referred to as a "set of associated drive schemes". As described in some of the aforementioned MEDEOD applications, it is also possible to use two or more drive schemes simultaneously within different areas of the same display, and the set of drive schemes used in this manner may be referred to as a "set of simultaneous drive schemes".

[0022] A further complexity in driving an electrophoretic display is the need for so-called "DC balance." As discussed in the aforementioned U.S. Patents Nos. 6,531,997 and 6,504,524, problems are encountered and the operating life time of the display can be reduced if the method used to drive the display does not result in a net time-averaged applied electric field that is zero or near zero across the electro-optic medium. Driving methods that result in a zero net time-averaged applied electric field across the electro-optic medium are conveniently referred to as "direct current balanced" or "DC balanced."

[0023] U.S. Patent No. 6,982,178 mentioned above also explains the importance of protecting electro-optical media from environmental contaminants since some electro-optical media are sensitive to humidity and ultraviolet radiation and most such media are vulnerable to mechanical damage. This published application illustrates in FIG. 10 a process in which a protective film is laminated over a front plane laminate in the same lamination operation by which the front plane laminate is laminated to the back plane, and such a protective film can protect the electro-optical media against the intrusion 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 published application teaches that it is also advisable for the display to include an edge seal, which serves to prevent the intrusion of moisture and other contaminants around the outer edges of the display. Various types of edge seals are illustrated in FIGS. 11 - 17 of U.S. Patent No. 6,982,178. Such edge seals can consist of a metallized foil or other barrier foil adhered over the edge of the FPL, a dispensed sealant (thermally, chemically, and / or radiation curable), a polyisobutylene or acrylate-based sealant, etc. Hybrid radiation and thermal curing sealants (i.e., UV curing with thermal post-curing) have been found to provide certain advantages in display system performance. The Threebond 30Y-491 material (manufactured by Threebond Corporation, Cincinnati, OH) is preferred especially for its favorable water vapor barrier properties, low viscosity at high temperatures for easy dispensing of the edge seal material, good wetting properties, and manageable curing characteristics. Those skilled in the art and those proficient in advanced sealants will be able to identify other sealants that provide equivalent performance. An exemplary edge seal having a width of about 2.5 mm is shown in FIG. 1.

[0024] FIG. 20 of the aforementioned U.S. Patent No. 6,982,178 shows a preferred form of an electro-optical display having a front protective layer and an edge seal. This preferred display generally resembles a backplane used with a liquid crystal display and includes a matrix of pixel electrodes, associated thin film transistors and conductors, a thin film transistor (TFT) backplane for independently controlling the voltage applied to the pixel electrodes. A tape connection package is connected to the peripheral portion of the backplane and 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 includes additional circuitry for controlling the operation of the display.

[0025] 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 conveniently formed from an indium tin oxide coated polymer film, and 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. A portion of the front electrode and the front substrate extends beyond the electro-optical layer, and in the extended portions of the front electrode and the 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.

[0026] On the front substrate, a first layer of optically transparent adhesive, a barrier film, a second layer of optically transparent adhesive, and, further, a relatively thick protective film (with an anti-reflection coating) provided on its exposed surface are continuously disposed. The protective film serves to prevent ultraviolet radiation from reaching the electro-optical layer and also prevents moisture or other contaminants in the atmosphere from reaching this layer.

[0027] 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 fabricated larger in both dimensions than the front substrate, and thus these layers have a peripheral portion that extends (or "overhangs") over the outer edge of the front substrate. To complete the sealing of the electro-optical layer, a curable edge sealing material is typically injected through a syringe into the area of the overhang and cured to form an edge seal that completely surrounds the electro-optical layer.

[0028] This type of edge seal is effective in preventing the ingress of moisture and other environmental contaminants into the electro-optical medium. However, one of the advantages of encapsulated electrophoretic media and other electro-optical media, such as twisted nematic members and microcell media, is that they are sufficiently flexible for use in flexible displays. The aforementioned type of edge seal and similar edge seals are not suitable for use in flexible displays because the edge seal itself imparts rigidity to the display.

[0029] Electro-optical displays, and more specifically, further improvements to edge seals in electrophoretic displays, can be found, for example, in U.S. Patent No. 7,649,674, which is incorporated herein by reference in its entirety. The '674 patent describes several different edge seal designs, including laminated sealing materials, single and double seal type protective sheets, single and double adhesive seals, and tape seals. For example, FIG. 2 shows a schematic cross-section through a single seal type protective sheet display (generally designated as 200) as disclosed in the '674 patent. This display 200 includes a backplane 202, a laminated adhesive layer 204, a layer of electro-optical material 206, a front substrate 208 including a light transmissive conductor, and a backplane 202, which may include an array of pixels coupled to thin film transistors. In particular, the backplane 202 is considerably wider than the layers 204-208 deposited as part of the front plane laminate, as described above, for example. As a result of this structure, a substantial peripheral portion 202P extends well beyond the edges of the active area of the layer of electro-optical material 206. This extra area, while it occupies a part of the display, is often referred to as "dead" because it cannot be switched between optical states (see FIG. 1). The width of the edge seal is generally designated as D ES in this document. In many cases, this dead area is covered by a decorative cover such as a case, frame, or bezel.

[0030] The display 200 further includes a front protective or barrier sheet 210, which also includes a peripheral portion 210P that extends outwardly beyond the edges of the layers 204-208. The peripheral portion 210P of the front barrier sheet 210 is sealed to the peripheral portion 202P of the backplane 202, for example, using laser or ultrasonic welding, by melting an appropriate portion of the front barrier sheet. Alternatively, the peripheral portions 210P and 202P can be fixed to each other using an adhesive.

[0031] As is apparent from FIG. 2, the edge seal width D ES is determined in many ways by the thickness and flexibility of the front protection or barrier sheet 210. Additionally, the way in which the peripheral portion of the substrate 202P is sealed to the peripheral portion of the front protection or barrier sheet 210P determines how closely the substrate 202 can be cut from the edge of the layer of electro-optic material 206. If a welding method is used, it may be possible to reduce the overall width of the substrate, however, if an adhesive is placed between 210P and 202P, a larger edge seal may be required (to explain for certainty, in a mass production type display module such as that in FIG. 1, the front plane laminate is cut to allow sufficient edge for sealing to the previously manufactured TFT backplane and not vice versa).

[0032] For many modern electronic displays, such as mobile phones, televisions, computer monitors, there is also an increasing need for thinner borders with respect to electrophoretic displays. In fact, in some applications, the edge seal width limits the width at which a bezel or frame must be used. Additionally, when electrophoretic displays are tiled together, the edge seal width has a significant impact on customer acceptance. A large format high resolution electrophoretic display with a non-switching line running through the center is simply not acceptable for high-end applications such as digital photos and artwork.

Prior Art Documents

Patent Documents

[0033]

Patent Document 1

Patent Document 2

Summary of the Invention

Means for Solving the Problems

[0034] The present invention provides an electrophoretic display including an integrated backplane, a layer of electrophoretic material disposed adjacent to the integrated backplane, a light-transmissive electrode layer adjacent to the layer of electrophoretic material, and an integrated front barrier. The integrated backplane includes a back electrode layer, an adhesive layer, a metal foil layer, and a substrate. The integrated front barrier includes an upper protective layer, a moisture barrier layer, and an optically transparent adhesive that joins the moisture barrier layer and the integrated backplane to create an edge seal. In some embodiments, the integrated front barrier is deformed at the edges to join the moisture barrier layer and the integrated backplane along the edges of the electrophoretic display and to enclose the layer of electrophoretic material and the light-transmissive electrode layer in the central portion. In some embodiments, the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated backplane is 1 mm or less. In some embodiments, the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated backplane is 0.5 mm or less. In some embodiments, the electrophoretic display further includes a layer of laminated adhesive between the integrated backplane and the layer of electrophoretic material. In some embodiments, the metal foil is a gold foil, a silver foil, an aluminum foil, or a copper foil. In some embodiments, the back electrode layer comprises indium tin oxide, conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene). In some embodiments, the electrophoretic material includes two or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties. In some embodiments, the electrophoretic material includes three or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties.

[0035] In another aspect, the present invention provides an electrophoretic display including an integrated back barrier, a back electrode layer, a layer of electrophoretic material disposed adjacent to the back electrode layer, a light-transmissive electrode layer adjacent to the layer of electrophoretic material on the opposite side from the back electrode layer, and an integrated front barrier. The integrated back barrier includes a back protective layer, a back moisture barrier layer, and a back laminated adhesive. The integrated front barrier includes an upper protective layer, a front moisture barrier layer, and an optically transparent adhesive that joins the front moisture barrier layer and the back electrode layer to create an edge seal. In some embodiments, the integrated front barrier is deformed at the edges to join the front moisture barrier layer and the back electrode layer along the edges of the electrophoretic display and to enclose the layer of electrophoretic material and the light-transmissive electrode layer in the central portion. In some embodiments, the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated back barrier is 1 mm or less. In some embodiments, the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated back barrier is 0.5 mm or less. In some embodiments, the electrophoretic display further includes a layer of laminated adhesive between the back electrode layer and the layer of electrophoretic material. In some embodiments, the back electrode layer is light-transmissive. In some embodiments, the back electrode layer comprises indium tin oxide, conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene). In some embodiments, the electrophoretic material includes two or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties. In some embodiments, the electrophoretic material includes three or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties. This specification also provides, for example, the following items. (Item 1) An electrophoretic display, wherein the electrophoretic display is an integrated backplane, and the integrated backplane comprises a back electrode layer, a polymer layer, a metal foil layer, and a substrate and is an integrated backplane, a layer of electrophoretic material disposed adjacent to the integrated backplane, a light-transmissive electrode layer adjacent to the layer of electrophoretic material, and an integrated front barrier and is provided with, wherein the integrated front barrier comprises an upper protective layer, a moisture-proof layer, and an optically transparent adhesive and comprises, wherein the optically transparent adhesive joins the moisture-proof layer and the integrated backplane to form an edge seal, an electrophoretic display. (Item 2) The integrated front barrier is deformed at the edge toward the integrated backplane to join the moisture-proof layer and the integrated backplane along the edge of the electrophoretic display and to enclose the layer of electrophoretic material and the layer of light-transmissive electrode in the central portion, the electrophoretic display according to Item 1. (Item 3) The integrated front barrier is deformed at the edge toward the integrated backplane, and the integrated backplane is deformed at the edge toward the integrated front barrier to join the moisture-proof layer and the integrated backplane along the edge of the electrophoretic display and to enclose the layer of electrophoretic material and the layer of light-transmissive electrode in the central portion, the electrophoretic display according to Item 1. (Item 4) The distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated backplane is 1 mm or less, the electrophoretic display according to Item 2 or Item 3. (Item 5) The distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated backplane is 0.5 mm or less, the electrophoretic display according to Item 4. (Item 6) The electrophoretic display according to Item 1 further comprises a layer of laminated adhesive between the integrated backplane and the layer of electrophoretic material. (Item 7) The metal foil is gold foil, silver foil, aluminum foil, or copper foil, the electrophoretic display according to Item 1. (Item 8) The back electrode layer comprises indium tin oxide, conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene), the electrophoretic display according to Item 1. (Item 9) The electrophoretic display according to item 1, wherein the electrophoretic material includes two or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties. (Item 10) The electrophoretic display according to item 1, wherein the electrophoretic material includes three or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties. (Item 11) An electrophoretic display, wherein the electrophoretic display is an integrated back barrier, and the integrated back barrier includes a back protective layer, a back moisture-proof layer and an integrated back barrier, a back electrode layer, a layer of electrophoretic material disposed adjacent to the back electrode layer, a light-transmissive electrode layer adjacent to the layer of electrophoretic material on the side opposite to the back electrode layer, and an integrated front barrier and is provided with wherein the integrated front barrier includes an upper protective layer, a front moisture-proof layer, and an optically transparent adhesive and the optically transparent adhesive joins the front moisture-proof layer and the back electrode layer to form an edge seal. An electrophoretic display. (Item 12) The electrophoretic display according to item 11, wherein the integrated front barrier joins the front moisture-proof layer and the back electrode layer along the edge of the electrophoretic display, and is deformed at the edge toward the integrated back barrier to wrap the layer of electrophoretic material and the light-transmissive electrode layer in the central portion. (Item 13) The electrophoretic display according to item 11, wherein the integrated front barrier is deformed at the edge toward the integrated back barrier, and the integrated back barrier joins the moisture-proof layer and the integrated backplane along the edge of the electrophoretic display, and is deformed at the edge toward the integrated front barrier to wrap the layer of electrophoretic material and the light-transmissive electrode layer in the central portion. (Item 14) The electrophoretic display according to item 12 or item 13, wherein the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated back barrier is 1 mm or less. (Item 15) The electrophoretic display according to item 14, wherein the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated back barrier is 0.5 mm or less. (Item 16) The electrophoretic display according to item 11, further comprising a layer of laminated adhesive between the back electrode layer and the layer of electrophoretic material. (Item 17) The electrophoretic display according to item 11, wherein the back electrode layer is light-transmissive. (Item 18) The electrophoretic display according to item 11, wherein the back electrode layer includes indium tin oxide, conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene). (Item 19) The electrophoretic display according to item 11, wherein the electrophoretic material includes two or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties. (Item 20) The electrophoretic display according to item 11, wherein the electrophoretic material includes three or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties.

Brief Description of the Drawings

[0036]

Figure 1

[0037]

Figure 2

[0038]

Figure 3

[0039]

Figure 4

[0040]

Figure 5

[0041]

Figure 6

[0042]

Figure 7

[0043]

Figure 8

[0044] It should be emphasized that all of 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 of the drawings, the thicknesses of the various layers are greatly exaggerated relative to their lateral dimensions.

[0045] As discussed in the background art, there are several approaches for sealing an electrophoretic display using a combination of a substrate, an edge seal material, and an assembly technique. The electrophoretic displays described herein provide a narrow edge seal, thereby reducing the width of the material at the edges of the sealed electrophoretic display that is inert.

[0046] 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 aforementioned patents and published applications, and means a rigid or flexible material having one or more electrodes. The backplane may comprise electronics for addressing the display, or such electronics may be provided in a unit separate from the backplane. In electrophoretic displays, 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, normally viewed from the side opposite the backplane).

[0047] As discussed in the aforementioned U.S. Pat. Nos. 6,982,178 and 7,110,164 and Patent Publication No. 2004 / 0155857, one preferred form of a front substrate for an electro-optical display comprises a thin layer of ITO on PET, and such coated films are readily commercially available. In such front substrates, the ITO layer serves as a barrier material, but in practice, commercially available PET / ITO is inevitably plagued with micropores and cracks through which moisture and other contaminants can penetrate to the electro-optical material.

[0048] 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, which redundant barrier layer may be 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) It is formed from. 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. If an adhesive layer is required to attach the redundant barrier to the front substrate, the adhesive layer should be transparent, colorless, thin, flexible, have low creep (when the display is bent or rolled), and be durable at all temperatures within the operating range of the display. Certain cross-linked polyurethanes and polyacrylates can be used as such adhesives.

[0049] Alternatively, the barrier properties of a PET / ITO or similar front substrate can be improved by coating a redundant metal oxide layer (e.g., an alumina layer) either on the opposite surface from the ITO layer of the front substrate or beneath the ITO 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 excessive yellowing of the substrate (such as would occur if attempting to improve the barrier properties by increasing the thickness of the ITO layer). Instead of a simple metal oxide layer, a more complex structure including a ceramic material such as the Barix® sealing material available from Vitex Systems, Inc. (3047 Orchard Parkway, San Jose, CA 95134) can be used, and as before, the barrier layer can be provided either on the surface of the front substrate remote from the ITO layer or beneath the ITO layer. Vitex Systems currently sells a polymer film that supports both a Barix layer and an ITO layer under the trade name FlexGlass 200, but the polymer film is 5 mils (127 μm) PEN.

[0050] Not only the barrier properties of the front substrate, but also properties such as flexibility, cost, and other special properties can be controlled by the careful selection of both the polymers and conductive materials used within the front substrate. Almost any flexible and optically transmissive polymer can, in principle, be used: 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).

[0051] A preferred display of the present invention will now be described, by way of example only, with reference to the accompanying drawings. In all cases, the electrophoretic layer can be any of a capsule electrophoretic layer, a polymer dispersed electrophoretic layer, or other types of electro-optic layers discussed above. The electrophoretic layer can be contained within microcells defined by microembossing a polymer such as acrylate to contain the electrophoretic medium, filling the microcells with the electrophoretic medium, and then sealing the microcells. The display can include one or two (or more) laminated adhesive layers to attach the layers of the electrophoretic display to each other or to attach to the front substrate and / or the backplane. The display can be viewed through any of the laminated adhesive layers, and the display can be assembled by direct coating and lamination, or by the use of a front plane laminate, an inverted front plane laminate, or a double release film, as described above.

[0052] The types of electrophoretic materials incorporated into the disclosed electrophoretic displays are not limited. For example, the electrophoretic media of the present invention can include two oppositely charged particles having different optical properties, such as white and black. However, the colors incorporated into the electrophoretic media are not limited and can include, for example, among others, red, orange, yellow, green, blue, purple, brown, pink, magenta, and cyan. The electrophoretic media can include three or more different sets of electrophoretic materials, such as those described in U.S. Patent Nos. 9,921,451 and 9,812,073, both of which are incorporated by reference in their entireties.

[0053] Figure 3 is a schematic illustration of an electrophoretic display (generally designated as 300) of the present invention. This display 300 includes an integrated backplane 320, a layer 306 of electrophoretic material, a layer 304 of laminated adhesive, a light-transmissive electrode layer 308, and an integrated front barrier 310. The integrated backplane 320 includes a back electrode layer 326, a polymer layer 324, a metal foil layer 322, and a substrate 321. The integrated backplane 320 can additionally include an adhesive layer between the metal foil layer 322 and the substrate 321. The light-transmissive electrode layer 308 can include indium tin oxide (ITO) sputtered onto a thin polyethylene terephthalate (PET), or it can include another light-transmissive electrode material such as conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene) (PEDOT). The PET can be 50 μm thick or less, for example, 30 μm thick or less, 25 μm thick or less, or 20 μm thick or less. In some cases, a conductive material (such as metal whiskers) is distributed within a transparent polymer matrix. The metal foil layer can include gold foil, silver foil, aluminum foil, or copper foil. The integrated backplane 320 is not limited to the structure described with respect to Figure 3 and can additionally include one or more additional flexible substrates, one or more additional adhesive layers, and one or more additional metal layers. In some cases, the integrated backplane 320 is flexible and can be deformed around the layers of electrophoretic material 306 and the layer of light-transmissive electrode layer 308 to join with the integrated front barrier 310.

[0054] The integrated front barrier 310 includes an upper protective layer 311, a moisture barrier layer 314, and an optically transparent adhesive 312. The integrated front barrier may include a second optically transparent adhesive 316 between the upper protective layer 311 and the moisture barrier layer 314. The peripheral portion 318 of the integrated front barrier is deformed so as to join the moisture barrier layer 314 and the integrated backplane 320 along the edge of the electrophoretic display while enclosing the layer of the electrophoretic material layer 306 and the light transmissive electrode layer 308 in the central portion. The upper protective layer 311 can be any of transparent deformable polymer materials such as polyethylene, polyacrylate, or polystyrene.

[0055] Edge seal distance D ES is defined as the minimum distance between the edge of the light transmissive electrode layer 308 and the edge of the integrated front barrier 310, or simply the distance between the edge of the light transmissive electrode layer 308 and the farthest extent of the upper protective layer 311, and the upper protective layer 311 may, in some cases, extend slightly beyond the moisture barrier layer 314. Using the structure shown in FIG. 3, it is possible to achieve a narrow edge seal, for example, D ESis 2 mm or less, for example, 1 mm or less, for example, 0.5 mm or less, for example, 0.2 mm or less. Compared to the prior art, for example, FIG. 1, it represents an edge seal that is 3 to 10 times thinner. Such a narrow-width edge seal is beneficial when the display is integrated into other devices for use as a decoration or indicator whose color changes, or when multiple displays are in contact (e.g., arranged like tiles). A narrow-width edge seal may also be desirable when the surface area is limited, such as in gemstones, or when integrated into a surface that is viewed up close, such as in sunglasses or augmented reality glasses. In some cases, the edges of the electrophoretic display may be further finished using laser ablation or ion beam ablation, for example, to further reduce the width of the peripheral region 318. The exposed surface at the interface between the integrated front barrier 310 and the integrated backplane 320 may be sealed with an edge barrier 340, which may be an acrylic, for example, cyanoacrylate, or a high-density polymer sealant such as polyurethane, or a sealing tape. In some embodiments, the edge barrier 340 may be a deposited material such as silicon nitride, aluminum nitride, aluminum oxide, or silicon oxide.

[0056] A second embodiment of the electrophoretic display of the present invention is shown in FIG. 4. This display 400 includes an integrated rear barrier 420, a rear electrode layer 430, a layer of electrophoretic material 406, a layer of laminated adhesive 404, a light-transmissive electrode layer 408, and an integrated front barrier 410. The integrated rear barrier 420 includes a rear protective layer 421, a rear moisture-proof layer 424, and a rear laminated adhesive 422. The light-transmissive electrode layer 408 and the rear electrode layer 430 may both, or optionally, include indium tin oxide (ITO) sputtered on thin polyethylene terephthalate (PET), or they may include another light-transmissive electrode material such as conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene) (PEDOT). The rear electrode layer 430 may not be light-transmissive. In some embodiments, each of the light-transmissive electrode layer 408 and the rear electrode layer 430 is 50 μm thick or less, for example, 30 μm thick or less, 25 μm thick or less, or 20 μm thick or less.

[0057] The integrated front barrier 410 includes an upper protective layer 411, a moisture-proof layer 414, and an optically transparent adhesive 412. The integrated front barrier 410 may include a second optically transparent adhesive 416 between the upper protective layer 411 and the moisture-proof layer 414. The peripheral portion 418 of the integrated front barrier is deformed to join the moisture-proof layer 414 and the rear electrode layer 430 along the edge of the electrophoretic display while enclosing the layer of electrophoretic material 406 and the light-transmissive electrode layer 408 in the central portion. The upper protective layer 411 may be any of transparent deformable polymer materials such as polyethylene, polyacrylate, or polystyrene.

[0058] Similar to FIG. 3, the width of the edge seal in the embodiment of FIG. 4 is the minimum distance between the edge of the light-transmissive electrode 408 layer and the edge of the rear electrode layer 430 or the integrated rear barrier 420, both of which extend further outward from the edge of the light-transmissive electrode 408. The exposed surface at the interface between the integrated front barrier 410 and the integrated rear barrier 420 may be sealed with an edge barrier 440, for example, as described above with respect to FIG. 3.

[0059] An alternative edge seal for FIG. 3 is shown in FIG. 5. In FIG. 5, the integrated front barrier 510 is deformed at the edge towards the integrated backplane 510, while at the same time, the integrated backplane 520 is deformed towards the integrated front barrier 510. This configuration may be referred to as a "clamping type edge" seal. Similar to FIG. 3, the display 500 of FIG. 5 includes an integrated backplane 520, a layer of electrophoretic material 506, a light transmissive electrode layer 508, and an integrated front barrier 510. The integrated backplane 520 includes a back electrode layer 526, a polymer layer 524, a metal foil layer 522, and a substrate 521. The integrated backplane 520 may additionally include an adhesive layer between the metal foil layer 522 and the substrate 521. The integrated backplane 520 is not limited to the structure described with respect to FIG. 5 and may additionally include one or more additional flexible substrates, one or more additional adhesive layers, and one or more additional metal layers. The integrated front barrier 510 includes an upper protective layer 511, a moisture barrier layer 514, and an optically transparent adhesive 512. The integrated front barrier 510 may include a second optically transparent adhesive 516 between the upper protective layer 511 and the moisture barrier layer 514. The peripheral portion 518 of the integrated front barrier is deformed to join the moisture barrier layer 514 and the integrated backplane 520 along the edge of the electrophoretic display while enclosing the layer of electrophoretic material 506 and the layer of light transmissive electrode layer 508 in the central portion. The upper protective layer 511 may be any of a transparent deformable polymer material such as polyethylene, polyacrylate, or polystyrene. Using the structure shown in FIG. 5, it is possible to achieve a narrow edge seal, for example, D ES is 2 mm or less, for example, 1 mm or less, for example, 0.5 mm or less, for example, 0.2 mm or less. In certain cases, the edge of the electrophoretic display will be further finished using laser ablation or ion beam ablation, for example, to further reduce the width of the peripheral region 518. The exposed surface at the interface between the integrated front barrier 510 and the integrated backplane 520 may be sealed with an edge barrier 540, which may be a high density polymer sealant such as acrylic, for example, cyanoacrylate, or polyurethane, or a sealing tape.

[0060] In different embodiments, as shown in FIG. 6, after the back electrode layer 526 and the polymer layer 524 are removed from the portion of the display that extends beyond the layer of electrophoretic material 506 and the lamination adhesive 504, a clamping-type edge seal similar to that of FIG. 5 can be formed. The integrated back barrier 620 includes the metal foil layer 522, the substrate 521, and optionally an adhesive layer (not shown). As in FIG. 5, the integrated front barrier 510 includes the upper protective layer 511, the moisture barrier layer 514, and the optically transparent adhesive 512. The peripheral portion 518 of the integrated front barrier 510 is deformed toward the integrated back barrier 620, while a portion of the integrated back barrier 620 wraps around the layer of electrophoretic material 506, the light transmissive electrode layer 508, and the layer of lamination adhesive 504 in the central portion and is deformed toward the integrated front barrier 510 to join the moisture barrier layer 514 and the metal foil layer 524 along the edge of the electrophoretic display with the optically transparent adhesive layer 512. The resulting stack is thinner, thereby allowing for a narrower edge seal. It should be understood that the deflection of the integrated front barrier 510 and the deflection of the integrated back barrier need not be symmetric.

[0061] A method of forming a narrow clamping type edge seal including an integrated backplane of a display 500 is shown in FIG. 7A. In this case, the peripheral portion 518 is extended, which simply uses larger segments of both the integrated front barrier 510 and the integrated backplane 520. After the seal is formed between the transparent adhesive 512 and the back electrode layer 526, the edge seal is trimmed using a laser 710 (or another cutting tool) to reduce the edge seal width. However, the resulting foil / backplane layer 720 may not be provided as a good seal, and thus, as shown in FIG. 7B, an edge barrier 540 that contacts both the exposed edge of the integrated front barrier 510 and the metal foil layer 522 is formed. This same edge seal method can be used in any of the above displays as shown in FIGS. 3-6. Additionally, in some embodiments, the metal foil layer 522 can be electrically coupled to the back electrode layer 526 to enable easy external connection to the back electrode layer.

[0062] An alternative method of forming a narrow clamping type edge seal including an integrated backplane of a display 600 is shown in FIG. 8A. In this case, the peripheral portion 518 is extended, which simply uses larger segments of both the integrated front barrier 510 and the back barrier layer 520. After the seal is formed between the moisture barrier layer 514 and the metal foil layer 522, the edge seal is trimmed using a laser 710 (or another cutting tool) to reduce the edge seal width. In some embodiments, as shown in FIG. 8B, an edge barrier 740 that contacts both the exposed edge of the integrated front barrier 510 and the metal foil layer 522 is formed. In some embodiments, the metal foil layer 522 can be electrically coupled to the back electrode layer 526 to enable easy external connection to the back electrode layer. In yet another alternative structure, the structure of FIG. 8B can be formed by cutting the back barrier layer 620 before assembling the remaining components of the display 600 and then clamping the integrated front barrier 510 and the back barrier layer 620 together, and thus, the moisture barrier layer 514 can be sealed to the metal foil layer 522.

[0063] The electrophoretic display of the present invention can be substantially rigid, or the materials can be selected such that the display can be bent. Such a display does not require the type of thick rigid sealing member found in some prior art displays, and on the premise that the backplane is sufficiently flexible, the peripheral portion of the backplane and the barrier sheet, or the peripheral portions of two barrier sheets (which are adhered to each other), can remain flexible. In some applications, the entire stack can be light transmissive except for a portion of the electrophoretic medium (i.e., charged pigment particles). In some embodiments, the electrophoretic medium can contain only one type of particle, and the display can be designed to provide an electric field suitable for moving the pigment particles to a "shielded" state in which the viewing area is substantially light transmissive.

[0064] The electrode arrangements 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 can be of the direct drive type, in which the backplane comprises a plurality of electrodes, each of which comprises a separate connector, using which the 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 arrangements are possible. Depending on the type of electro-optic material used, it may be possible to use a passive matrix drive arrangement where the (typically) backplane supports 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") running perpendicular to the column electrodes are provided, and the overlap between one particular column electrode and one particular row electrode defines one pixel of the display. This display can 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 to write to the display row by row. Finally, this display can also be of the stylus drive type, (typically) with a single electrode on the backplane, and without a permanent front electrode, and the writing to the display is effected by moving a stylus across the front surface of the display.

[0065] The displays of the present invention can be used in any application in which prior art electro-optic displays have been used. Thus, for example, the displays can be used in e-book readers, portable computers, tablet computers, mobile phones, smart cards, billboards, wristwatches, shelf labels, flash drives.

[0066] Numerous changes and modifications can be made to the preferred embodiments of the invention already described without departing from the scope of the invention. Accordingly, the foregoing description is to be construed in an illustrative rather than a limiting sense.

Claims

1. An electrophoretic display, wherein the electrophoretic display comprises: An integrated backplane, wherein the integrated backplane comprises: A back electrode layer; A polymer layer; A metal foil layer; A substrate An integrated backplane including the above; A layer of electrophoretic material disposed adjacent to the integrated backplane; A light-transmissive electrode layer adjacent to the layer of electrophoretic material; An integrated front barrier, wherein the integrated front barrier comprises: An upper protective layer; A moisture-proof layer; An optically transparent adhesive An integrated front barrier, wherein the optically transparent adhesive joins the moisture-proof layer and the integrated backplane to form an edge seal; An edge barrier having a high-density polymer sealant covering the exposed surface at the interface between the integrated front barrier and the integrated backplane in the edge seal; Comprising the above; The electrophoretic display, wherein the optically transparent adhesive is disposed adjacent to the moisture-proof layer and adjacent to the light-transmissive electrode layer.

2. The electrophoretic display according to claim 1, wherein the integrated front barrier joins the moisture-proof layer and the integrated backplane along the edge of the electrophoretic display and is deformed at the edge towards the integrated backplane to enclose the layer of electrophoretic material and the light-transmissive electrode layer in the central portion.

3. The electrophoretic display according to claim 1, wherein the integrated front barrier is deformed at the edge towards the integrated backplane, and the integrated backplane joins the moisture-proof layer and the integrated backplane along the edge of the electrophoretic display and is deformed at the edge towards the integrated front barrier to enclose the layer of electrophoretic material and the light-transmissive electrode layer in the central portion.

4. The electrophoretic display according to claim 2 or claim 3, wherein the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated backplane is 1 mm or less.

5. The electrophoretic display according to claim 4, wherein the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated backplane is 0.5 mm or less.

6. The electrophoretic display according to claim 1, further comprising a layer of laminated adhesive between the integrated backplane and the layer of electrophoretic material.

7. The electrophoretic display according to claim 1, wherein the metal foil is gold foil, silver foil, aluminum foil, or copper foil.

8. The electrophoretic display according to claim 1, wherein the back electrode layer comprises indium tin oxide, conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene).

9. The electrophoretic display according to claim 1, wherein the electrophoretic material includes two or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties.

10. The electrophoretic display according to claim 1, wherein the electrophoretic material includes three or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties.

11. An electrophoretic display, wherein the electrophoretic display is an integrated back barrier, and the integrated back barrier includes a back protective layer, a back moisture-proof layer and an integrated back barrier, a back electrode layer, a layer of electrophoretic material disposed adjacent to the back electrode layer, a light-transmissive electrode layer adjacent to the layer of electrophoretic material on the opposite side from the back electrode layer, is an integrated front barrier, and the integrated front barrier includes an upper protective layer, a front moisture-proof layer, and an optically transparent adhesive and the optically transparent adhesive joins the front moisture-proof layer and the back electrode layer to form an edge seal, and an integrated front barrier, and an edge barrier having a high-density polymer sealant covering the exposed surface at the interface between the integrated front barrier and the back electrode layer in the edge seal and is provided with the electrophoretic display, wherein the optically transparent adhesive is disposed adjacent to the front moisture-proof layer and adjacent to the light-transmissive electrode layer.

12. The electrophoretic display according to claim 11, wherein the integrated front barrier is deformed at the edge toward the integrated back barrier to join the front moisture-proof layer and the back electrode layer along the edge of the electrophoretic display and to enclose the layer of electrophoretic material and the light-transmissive electrode layer at the central portion.

13. The electrophoretic display according to claim 11, wherein the integrated front barrier is deformed at the edge toward the integrated back barrier, and the integrated back barrier is deformed at the edge toward the integrated front barrier to join the front moisture-proof layer and the integrated back barrier along the edge of the electrophoretic display and to enclose the layer of electrophoretic material and the light-transmissive electrode layer at the central portion.

14. The electrophoretic display according to claim 12 or claim 13, wherein the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated back barrier is 1 mm or less.

15. The electrophoretic display according to claim 14, wherein the distance between the edge of the light-transmissive electrode layer and the outer edge of the integrated back barrier is 0.5 mm or less.

16. The electrophoretic display according to claim 11, further comprising a layer of a laminated adhesive between the back electrode layer and the layer of the electrophoretic material.

17. The electrophoretic display according to claim 11, wherein the back electrode layer is light-transmissive.

18. The electrophoretic display according to claim 11, wherein the back electrode layer comprises indium tin oxide, conductive carbon, graphene, nanotubes, metal whiskers, or poly(3,4-ethylenedioxythiophene).

19. The electrophoretic display according to claim 11, wherein the electrophoretic material includes two or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties.

20. The electrophoretic display according to claim 11, wherein the electrophoretic material includes three or more sets of charged particles that move in response to an electric field, and each set of charged particles has different optical properties.

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