A variable light transmission device comprising microcells

Abstract

A variable light transmission device is disclosed, which can mitigate negative aperture diffraction effects and exhibit good switching speed between open and closed optical states. The device includes a microcell layer disposed between two light-transmitting electrode layers, the microcell layer having a plurality of microcells, each microcell containing an electrophoretic medium, and each microcell including a protrusion structure having one or more wells.

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 664,300, filed June 26, 2024, the entire contents of which, along with all other patents and patent applications disclosed herein, are incorporated herein by reference.

[0002] This invention relates to a variable light transmission device. Specifically, it relates to a microcellular electro-optic device comprising an electrophoretic medium containing charged pigment particles and a nonpolar liquid. This electrophoretic medium can be switched between optical states using an electric field. The variable light transmission device can adjust the amount of light passing through it and other electromagnetic radiation. It can be used in mirrors, windows, skylights, and similar objects. For example, this invention can be applied to windows that can regulate the amount of light entering buildings and vehicles. Examples of electrophoretic media that can be incorporated into various embodiments of the present invention include, for example, those described in U.S. Patent Nos. 7,116,466, 7,327,511, 8,576,476, 10,319,314, 10,809,590, 10,067,398, 10,067,398 and 11,143,930, and U.S. Patent Application Publications Nos. 2014 / 0055841, 2017 / 0351155, 2017 / 0235206, 2011 / 0199671, 2020 / 0355979, 2020 / 0272017, 2021 / 0096439, and U.S. Patent Application No. 17 / 953,386, filed September 27, 2022, the entire contents of which are incorporated herein by reference. Prior Technology

[0003] Particle-based electrophoretic displays have been a subject of intensive research for several years, in which multiple charged pigment particles move through a suspended fluid under the influence of an electric field. Compared with liquid crystal displays, such displays have advantages such as good brightness and contrast, wide viewing angle, dual stability, and low power consumption.

[0004] The terms "bistable" and "bistability" are used herein in their conventional sense to refer to a display comprising display elements having first and second display states that are different in at least one optical property, and to present either the first or second display state after any given element is driven by an addressing pulse of finite duration, and that state persists at least several times, for example, at least four times, after the addressing pulse terminates; the addressing pulse requires a minimum duration to change the state of the display element. Published U.S. Patent Application No. 2002 / 0180687 shows that some particle-based electrophoretic displays with grayscale capabilities are stable not only in their extreme black and white states but also in their intermediate gray states, and similarly, some other types of electro-optic displays. Such displays may be appropriately called multi-stable rather than bistable, but for convenience, the term "bistable" may be used herein to encompass both bistable and multi-stable displays.

[0005] As mentioned above, electrophoretic media require the presence of a suspending fluid. In most conventional electrophoretic media, this suspension system is liquid, but gaseous suspensions can be used to produce electrophoretic media. When used in an orientation that allows particle settling (e.g., in the case of media arranged in a vertical plane), such gas-based electrophoretic media appear to be susceptible to the same type of problems caused by particle settling as liquid-based electrophoretic media. More precisely, particle settling appears to be a more severe problem in gas-based electrophoretic media than in liquid-based electrophoretic media because the lower viscosity of gaseous suspensions allows charged pigment particles to settle more rapidly compared to liquid suspensions.

[0006] 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 techniques used in encapsulation and microelectrophoresis and other electro-optic media. Encapsulation electrophoretic media comprises a plurality of microcapsules, each capsule comprising an internal phase containing electrophoretically moving particles in a liquid medium and a capsule wall surrounding the internal phase. Typically, these capsules are themselves held in a polymeric binder to form a coherent layer between two electrodes. In microelectrophoretic displays, charged pigment particles and liquid are not encapsulated within microcapsules but are retained within a plurality of cavities formed in a carrier medium (typically a polymer film). The techniques described in these patents and applications include: (a) Electrophoretic particles, fluids, and fluid additives; see, for example, U.S. Patent Nos. 5,961,804; 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; 7,0 02,728;7,038,655;7,052,766;7,110,162;7,113,323;7,141,688;7,142,351;7,170,670;7,226,550;7,230,750;7,230,751;7,236,290;7,277,21 8;7,286,279;7,312,916;7,382,514;7,390,901;7,473,782;7,561,324;7,583,251;7,572,394;7,576,904;7,580,180;7,679,814;7,848,006;7,9 03,319;8,018,640;8,115,729;8,257,614;8,270,064;8,363,306;8,390,918;8,582,196;8,654,436;8,902,491;8,961,831;9,052,564;9,341,9 15;9,348,193;9,361,836;9,366,935;9,372,380;9,382,427;9,423,666;9,428,649;9,557,623;9,670,367;9,671,667;9,688,859;9,726,957;9, 752,034;9,765,015;9,778,535;9,778,537;9,835,926;9,953,588;9,995,987;10,025,157;10,031,394;10,040,954;10,061,123;10,062,337;10,147,366; and 10,514,583; and U.S. Patent Application Publications 2003 / 0048522;2003 / 0151029;2003 / 0164480;2004 / 0030125;2004 / 0105036;2005 / 0012980;2009 / 0009852;2011 / 0217639; 2012 / 0049125; 2013 / 0161565; 2013 / 0193385; 2013 / 0244149; 2013 / 0063333; 2014 / 0011913; 2014 / 0078576; 2014 / 0104674; 2014 / 0231728; 2015 / 0177590; 2015 / 0185509; 2015 / 0241754; 2015 / 0301425; and 2016 / 0170106; (b) Capsules, binders, and encapsulation processes; see, for example, U.S. Patents 5,930,026; 6,067,185; 6,130,774; 6,262,706; 6,327,072; 6,392,786; 6,459,418; 6,727,881; 6,839,158; 6,866,760; 6,922,276; 6,958,848; 6,987,603; 7,110,164; 7,14 U.S. Patent Application Publications Nos. 8,128; 7,184,197; 7,304,634; 7,327,511; 7,339,715; 7,411,719; 7,477,444; 7,561,324; 7,910,175; 7,952,790; 8,129,655; 8,446,664; and U.S. Patent Application Publications Nos. 2005 / 0156340; 2007 / 0091417; and 2009 / 0122389; (c) Microcellular structures, wall materials, and methods of forming microcells; see, for example, U.S. Patents 6,672,921; 6,751,007; 6,753,067; 6,781,745; 6,788,452; 6,795,229; 6,806,995; 6,829,078; 6,850,355; 6,865,012; 6,870,662 ;6,885,495;6,930,818;6,933,098;6,947,202;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;7,304,78 0;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;8,891,1 56; 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 / 0203101; 2014 / 0050814; and 2016 / 0059442; (d) Methods for filling and sealing microcells; see, for example, U.S. Patent Nos. 6,545,797; 6,788,449; 6,831,770; 6,833,943; 6,930,818; 7,046,228; 7,052,571; 7,166,182; 7,347,957; 7,374,634; 7,385,751; 7,408,696; 7,557,981; 7,560,004; 7 U.S. Patent Application Publications Nos. 564,614; 7,572,491; 7,616,374; 7,715,087; 7,715,088; 8,361,356; 8,625,188; 8,830,561; 9,346,987; and 9,759,978; and U.S. Patent Application Publications Nos. 2002 / 0188053; 2004 / 0120024; 2004 / 0219306; and 2015 / 0098124; (e) Thin films and sub-assemblies containing electro-optic materials; see, for example, U.S. Patents 6,825,829; 6,982,178; 7,110,164; 7,158,282; 7,554,712; 7,561,324; 7,649,666; 7,728,811; 7,826,129; 7,839,564; 7,843,621; 7,843,624; 7,952,790; 8,034,209; 8,177,942; 8,390,301; 9,238,340; 9,470,950; U.S. Patent Application Publication Nos. 9,835,925; and U.S. Patent Application Publication Nos. 2005 / 0122563; 2007 / 0237962; and 2011 / 0164301; (f) Backplates, adhesive layers, and other auxiliary layers used in displays, and methods thereof; see, for example, U.S. Patent Nos. D485,294; 5,930,026; 6,120,588; 6,124,851; 6,177,921; 6,232,950; 6,252,564; 6,312,304; 6,312,971; 6,376,828; 6,392,786; 6,413,790; 6,480,182; 6,498,114; 6,506,438; 6,518,949; 6,545,291; 6,639,578; 6,657,772; 6,664,944; 6,683,333; 6 710,540;6,724,519;6,816,147;6,819,471;6,825,068;6,831,769;6,842,279;6,842,657;6,865,010;6,873,452;6,909,532;6,967,640;7,012,6 00;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;7,301,693;7,304,780;7,327,346;7,327,511;7,347,957;7,365,733;7,388,572;7,401,758;7,492,4 97;7,535,624;7,551,346;7,554,712;7,560,004;7,583,427;7,649,674;7,667,886;7,672,040;7,688,497;7,826,129;7,830,592;7,839,564;7, 880,958;7,893,435;7,905,977;7,952,790;7,986,450;8,034,209;8,049,947;8,072,675;8,120,836;8,159,636;8,177,942;8,237,892;8,362,4 88;8,395,836;8,437,069;8,441,414;8,456,589;8,514,168;8,547,628;8,576,162;8,610,988;8,714,780;8,743,077;8,754,85​​9;8,797,258;8,797,633;8,797,636;9,147,364;9,025,234;9,025,238;9,030,374;9,140,​​952;9,201,279;9,223,164;9,238,340;9,285,648;9,454,057;9,529,240;9,620,066;9 ,632,373;9,666,142;9,671,635;9,715,155;9,777,201;9,897,891;10,037,735;10,190,743;10,324,577;10,365,533;10,372,008;10,446,585;10,466,565;10,495,9 41;10,503,041;10,509,294;10,613,407; and U.S. Patent Application Publication Nos. 2002 / 0060321; 2004 / 0085619; 2004 / 0105036; 2005 / 0122306; 2005 / 0122563; 2006 / 0255322; 2009 / 0122389;201 Applications Nos. 0 / 0177396, 2011 / 0164301, 2011 / 0292319, 2014 / 0192000, 2014 / 0210701, 2014 / 0368753, and 2016 / 0077375; and International Application Publications Nos. WO2000 / 038000, WO2000 / 005704, and WO1999 / 067678; (g) Color formation and color adjustment; see, for example, U.S. Patents 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; 7,385,7 51;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;8,213,0 76;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; and 9,423,666; and U.S. Patent Application Publications 2008 / 0043318;2008 / 0048970;2009 / 0225398;2010 / 0156780;2011 / 0043543;2012 / 0326957;201 3 / 0242378;2013 / 0278995;2014 / 0055840;2014 / 0078576;2014 / 0340430;2014 / 0340736;2014 / 0362213;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) A method for driving a display; see, 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; 7,3 12,794;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;9,082,352;9,171,508;9,218,77 3;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 9,412,314;And U.S. Patent Application Publications 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 / 0195568; 2 009 / 0322721;2010 / 0194733;2010 / 0194789;2010 / 0220121;2010 / 0265561;2010 / 0283804;2011 / 0063314;2011 / 0175875;2011 / 0193840;2011 / 0193841;2011 / 0199671;2011 / 0221740;2012 / 0001957;2012 / 0098740;20 13 / 0063333;2013 / 0194250;2013 / 0249782;2013 / 0321278;2014 / 0009817;2014 / 0085355;2014 / 0204012;2014 / 0218277;2014 / 0240210;2014 / 0240373;2014 / 0253425;2014 / 0292830;2014 / 0293398;2014 / 0333685;20 14 / 0340734; 2015 / 0070744; 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; (i) Applications of displays; see, for example, U.S. Patents 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; and 9,197,704; and U.S. Patent Application Publications 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 WO 00 / 36560; and (j) Non-electrophoretic displays, such as those described in U.S. Patent Nos. 6,241,921; 6,784,953; 6,795,138; 6,914,713; 6,950,220; 7,095,477; 7,182,830; 7,245,414; 7,420,549; 7,471,369; 7,576,904; 7,580,180; 7,850,867; 8,018,643; 8,023,071; 8,282,762; 8,319,759; and 8,9 See, for example, U.S. Patent Application Publications 2005 / 0099575; 2006 / 0262249; 2007 / 0042135; 2007 / 0153360; 2008 / 0020007; 2012 / 0293858; and 2015 / 0277160; as well as packaging and applications of micro-cell technology other than displays; see, for example, U.S. Patent No. 7,615,325; and U.S. Patent Application Publications 2015 / 0005720 and 2016 / 0012710.

[0007] Many of the aforementioned patents and applications recognize that the walls surrounding discrete microcapsules in an encapsulated electrophoretic medium can be replaced by a continuous phase, thereby producing a so-called polymer dispersion electrophoretic display, wherein the electrophoretic medium comprises a plurality of discrete droplets of a nonpolar liquid and a continuous phase of polymeric material, and even without discrete capsule membranes associated with each individual droplet, the electrophoretic medium of the discrete droplets within such a polymer dispersion electrophoretic display can be considered as capsules or microcapsules; see, for example, the aforementioned U.S. Patent Application Publication No. 2002 / 0131147. Thus, for the purposes of this application, such polymer dispersion electrophoretic media are considered a subtype of encapsulated electrophoretic media.

[0008] One related type of electrophoretic display is the so-called "microcellular electrophoresis display." In a microcellular electrophoresis display, instead of encapsulating charged pigment particles and suspended liquid in microcapsules, they are held in multiple cavities formed within a carrier medium (e.g., a polymer membrane). See, for example, International Application Publication No. WO 02 / 01281 and published U.S. Application No. 2002 / 0075556, both of which have been assigned to Sipix Imaging, Inc.

[0009] Although electrophoretic media are typically opaque (because, for example, in many electrophoretic media, particles substantially block the transmission of visible light through the display) and operate in a light-reflective mode, many electrophoretic displays can also operate in a so-called "shutter mode," in which one display state is substantially opaque and another display state is transparent. See, for example, the aforementioned 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. Dielectrophoretic displays (which are similar to electrophoretic displays but depend on changes in electric field strength) can operate in a similar mode; see U.S. Patent 4,418,346. Other types of electro-optic displays can also operate in shutter mode.

[0010] An encapsulated or microcellular electrophoretic display typically does not suffer from the clustering and settling failure modes of conventional electrophoretic devices and offers additional advantages, such as the ability to print or coat the display on a variety of flexible and rigid substrates. The term "printing" is intended to encompass all forms of printing and coating, including but not limited to: pre-metered coatings (e.g., patch die coating, slot or extrusion coating, slide or cascade coating, and curtain coating); roll coating (e.g., knife over roll coating and forward and reverse roll coating; gravel coating); dip coating; spray coating; meniscus coating; spin coating; brush coating; air-knife coating; silk screen printing processes; electrostatic printing processes; thermal printing processes; and inkjet printing processes. Printing processes); electrophoretic deposition; and other similar techniques. Therefore, the resulting display can be flexible. Furthermore, because the display medium can be printed (using various methods), the display itself can be manufactured inexpensively.

[0011] One potentially important market for electrophoretic media is windows with variable transmittance. As energy efficiency in buildings and transportation becomes increasingly important, electrophoretic media can be used as a coating on windows to electrically control the proportion of incident radiation transmitted through the window by changing the optical state of the electrophoretic media. The effective implementation of this "variable transmittance" ("VT") technology in buildings is expected to (1) reduce unnecessary heating effects during hot weather, thereby reducing the energy required for cooling, the size of air conditioning equipment, and peak power demand; (2) increase the utilization of natural light, thereby reducing lighting energy and peak power demand; and (3) improve occupant comfort by increasing thermal and visual comfort. Greater benefits can be obtained in automobiles, where the ratio of glass surface area to enclosed volume is significantly greater than in typical buildings. Specifically, the effective implementation of VT technology in automobiles is expected to not only provide the above benefits, but also (1) improve driving safety, (2) reduce glare, (3) enhance mirror performance (by using electro-optic coatings on mirrors), and (4) enhance the ability to use head-up displays. Other potential applications of VT technology include privacy glass in electronic devices and anti-glare screen protectors.

[0012] This technology provides an example of an apparatus comprising an electrophoretic medium sandwiched between electrode layers, the electrophoretic medium being capable of achieving a closed optical state (opaque optical state) and an open optical state (transparent optical state) and switching between these states by applying an electric field throughout the electrophoretic medium. However, conventional electrophoretic apparatuses employing conventional structures and waveforms require long switching times. Furthermore, light from luminescent objects (e.g., light sources) in dark environments or mirror-reflected light from the sun in bright environments can easily diffract when passing through the apparatus, a phenomenon visible to the viewer and even causing disturbance, thus making the apparatus less desirable. The inventors of this invention have unexpectedly discovered that a device comprising microcellular layers with a specific architecture can achieve efficient switching between open and closed optical states and improve the optical performance of the open optical state. Summary of the Invention

[0013] In one embodiment, the present invention provides a variable light transmission device (200, 300, 350) according to a first embodiment. The variable light transmission device according to the first embodiment includes a first light-transmitting electrode layer (202), a second light-transmitting electrode layer (207), and a microcell layer (203). The microcell layer (203) is disposed between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207). The microcell layer (203) includes a plurality of microcells (204) and a sealing layer (206). Each microcell in the plurality of microcells (204) includes an electrophoretic medium (209) comprising charged pigment particles and a nonpolar liquid. Each microcell in the plurality of microcells (204) has a microcell opening (205). The sealing layer (206) spans the microcell openings (205) of the plurality of microcells (204). Each microcell's sealing layer (206) has an upper surface and a lower surface. The lower surface is in contact with the electrophoretic medium (209), and the upper surface is in contact with (i) the first light-transmitting electrode layer (202) or (ii) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the upper surface of the sealing layer (206). Each of the plurality of microcells (204) includes a microcell bottom layer (210), a protruding structure (217), and a microcell wall (212). The microcell bottom layer (210) has a microcell bottom inner surface (211).

[0014] According to the first embodiment, the protrusion structure (217) of a microcell of the variable light transmission device comprises a protrusion structure solid portion (217a) and one or more wells (217b). The protrusion structure (217) has a protruding bottom surface (218), a top plane (229), and a protrusion height (220). The protrusion structure solid portion (217a) has a protrusion structure solid portion top surface (219), a protrusion structure solid portion side surface (221), and a protrusion structure solid portion bottom surface (218a). The protrusion structure solid portion top surface (219) is a point or set of points of the protrusion structure solid portion (217a), which is shorter than all other points of the protrusion structure solid portion (217a) at a distance from the microcell opening (205). The top plane (229) is a plane parallel to the plane of the microcell opening (205) and encompassing the protrusion structure solid portion top surface (219). The side surface (221) of the solid portion of the protruding structure is the surface in contact with the electrophoretic medium (209) of the solid portion of the protruding structure (excluding the top end (219) of the solid portion of the protruding structure). The bottom surface (218a) of the solid portion of the protruding structure is the surface in contact with the inner surface (211) of the bottom of the microcell. The bottom surface (218) of the protrusion is the surface in contact with the solid portion of the protruding structure and the one or more wells and the bottom layer (210) of the microcell. The protrusion height (220) is the distance between the top plane (229) and the bottom surface (218) of the protrusion. The protruding structure (217) has a three-dimensional shape. The structure is a cylinder or a polygonal prism having a first base and a second base, each having 3 to 20 sides. The one or more wells (217b) of the protrusion structure (217) have a volume filled with the electrophoretic medium (209). Each of the one or more wells (217b) has a three-dimensional shape composed of one geometric shape or a combination of two or more geometric shapes. The three-dimensional shape of each of the one or more wells (217b) is defined by the space between (i) the top plane (229), (ii) the side surface (221) of the solid portion of the protrusion structure, and (iii) the inner surface (211) of the bottom of the microcell.The three-dimensional shape of each of the one or more wells, and each of the two or more geometric shapes, is selected from the group consisting of: a cone, a frustum of a cone, a cylinder, a polygonal pyramid, a frustum of a polygonal pyramid, and a polygonal prism; the cone having a base and a apex; the frustum of a cone having a large base and a small base; the cylinder having a first base and a second base; the polygonal pyramid having a base and a apex, the base of the polygonal pyramid being a polygon with 3 to 20 sides; the frustum of a polygon having a large base and a small base, the large and small bases of the frustum of a polygon having 3 to 20 sides; and the polygonal prism having a first base and a second base, the first and second bases of the polygonal prism being polygons with 3 to 20 sides.

[0015] According to the first embodiment, the cell wall (212) of a microcell in the variable light transmission device has an inner surface (213) and an upper surface (214). The inner surface (213) is the surface in contact between the cell wall (212) and the electrophoretic medium (209). The upper surface (214) is the surface in contact between the cell wall (212) and the sealing layer (206).

[0016] In one embodiment, the present invention provides a variable light transmission device (500, 550, 580, 590, 600, 650) according to a second embodiment. The variable light transmission device according to the second embodiment includes a first light-transmitting electrode layer (202), a second light-transmitting electrode layer (207), and a microcell layer (203). The microcell layer (203) is disposed between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207). The microcell layer (203) includes a plurality of microcells (204) and a sealing layer (206). Each microcell (204) contains an electrophoretic medium (209) comprising charged pigment particles and a nonpolar liquid. Each of the plurality of microcells (204) has a microcell opening (205), and the sealing layer (206) spans the microcell openings (205) of the plurality of microcells (204). The sealing layer (206) of each microcell has an upper surface and a lower surface, the lower surface being in contact with the electrophoretic medium (209), and the upper surface being in contact with (i) the first light-transmitting electrode layer (202) or (ii) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the upper surface of the sealing layer (206).

[0017] Each of the plurality of microcells (204) in the variable light transmission device according to the second embodiment includes a microcell bottom layer (210), a channel (215), a protrusion structure (217), and a microcell wall (212). The microcell bottom layer (210) has a microcell bottom inner surface (211). The microcell wall (212) has a microcell wall inner surface (213) and a microcell wall upper surface (214). The microcell wall inner surface (213) is the surface in contact with the electrophoretic medium (209). The microcell wall upper surface (214) is the surface in contact with the sealing layer (206).

[0018] According to the second embodiment, the protrusion structure (217) of a microcell of the variable light transmission device comprises a protrusion structure solid portion (217a) and one or more wells (217b). The protrusion structure (217) has a protruding bottom surface (218), a top plane (229), and a protrusion height (220). The protrusion structure solid portion (217a) has a protrusion structure solid portion top surface (219), a protrusion structure solid portion side surface (221), and a protrusion structure solid portion bottom surface (218a). The protrusion structure solid portion top surface (219) is a point or set of points of the protrusion structure solid portion (217a), which is shorter than all other points of the protrusion structure solid portion (217a) at a distance from the microcell opening (205). The top plane (229) is a plane parallel to the plane of the microcell opening (205) and encompassing the protrusion structure solid portion top surface (219). The side surface (221) of the protruding structural solid portion is the surface of the protruding structural solid portion (217a) that contacts the electrophoretic medium (209) (excluding the top surface (219) of the protruding structural solid portion). The bottom surface (218a) of the protruding structural solid portion is the surface of the protruding structural solid portion (217a) that contacts the inner surface (211) of the bottom of the microcell. The bottom surface (218) of the protrusion is the surface of the protruding structural solid portion and the one or more wells that contact the bottom layer (210) of the microcell, and the protrusion height (220) is the distance between the top surface (229) and the bottom surface (218) of the protrusion.

[0019] The protrusion structure of a microcell in the variable light transmission device of the second embodiment has a three-dimensional shape, which is composed of one geometric shape or a combination of two or more geometric shapes. Each of the one geometric shape and the two or more geometric shapes in the three-dimensional shape of the protrusion structure is selected from the group consisting of: a cylinder, a polygonal prism, a frustum of a cone, and a frustum of a pyramid; the cylinder has a first base and a second base; the polygonal prism has a first base and a second base, and the first base and the second base of the polygonal prism are polygons with 3 to 20 sides; the frustum of a cone has a large base and a small base; the frustum of a pyramid has a large base and a small base, and the large base and the small base of the frustum of a pyramid are polygons with 3 to 20 sides.

[0020] The side surface (221) of the protruding structural solid portion of a microcell in the second embodiment of the variable light transmission device is composed of an inner side surface (221b) and an outer side surface (221a) of the protruding structural solid portion. The inner side surface (221b) is the portion of the side surface (221) that contacts the one or more wells (217b). The outer side surface (221a) is the portion of the side surface (221) that does not contact the one or more wells (217b). The bottom inner surface (211) of the microcell is composed of an unexposed bottom inner surface (211a), a first exposed bottom inner surface (211b), and a second exposed bottom inner surface (211c). The unexposed bottom inner surface (211a) contacts the bottom surface (218a) of the protruding structural solid portion but does not contact the electrophoretic medium (209). The first exposed inner surface of the microcell base (211b) and the second exposed inner surface of the microcell base (211c) are in contact with the electrophoresis medium (209). The first exposed inner surface of the microcell base (211b) is in contact with the channel (215), and the second exposed inner surface of the microcell base (211c) is in contact with the one or more wells (217b).

[0021] The channel (215) of a microcell in the variable light transmission device of the second embodiment has a channel height (216h), an inner bottom perimeter (225), and an outer bottom perimeter (226). The channel (215) has a volume filled with the electrophoretic medium (209). The channel is a three-dimensional shape defined by the outer surface (221a) of the protruding structural solid portion, the inner surface (211b) of the first exposed microcell bottom, the inner surface (213) of the microcell wall, and a plane parallel to the inner surface (211b) of the first exposed microcell bottom. The distance between the plane and the inner surface (211b) of the first exposed microcell bottom is equal to the channel height (216h), which is 50% of the protrusion height (220). The inner bottom perimeter (225) is the intersection of the microcell wall (212) and the inner surface (211b) of the first exposed microcell bottom. The perimeter (226) of the outer bottom surface is the intersection of the outer surface (221a) of the solid part of the protruding structure and the inner surface (211b) of the bottom of the first exposed microcell.

[0022] According to the second embodiment, each well (217b) of the protrusion structure (217) of a microcell of the variable light transmission device has a volume filled with the electrophoretic medium (209). Each well (217b) has a three-dimensional shape composed of one geometric shape or a combination of two or more geometric shapes. The three-dimensional shape of each well (217b) is defined by the space between (i) the top plane (229), (ii) the inner surface (221b) of the solid portion of the protrusion structure, and (iii) the inner surface (211c) of the second exposed bottom of the microcell. The three-dimensional shape of each of the one or more wells, and each of the two or more geometric shapes, is selected from the group consisting of: a cone, a frustum, a cylinder, a polygonal pyramid, a frustum, and a prism, wherein the cone has a base and a apex, the frustum has a large base and a small base, the cylinder has a first base and a second base, the polygonal pyramid has a base and a apex, the base of the polygonal pyramid is a polygon with 3 to 20 sides, the frustum has a large base and a small base, the large and small bases of the frustum are polygons with 3 to 20 sides, and the prism has a first base and a second base, the first and second bases of the prism are polygons with 3 to 20 sides.

[0023] The variable light transmission device according to the first and second embodiments has a first outer surface (250) and a second outer surface (251). The first outer surface (250) is located on the side of the variable light transmission device closer to the first light-transmitting electrode layer (202), and the second outer surface (251) is located on the side of the variable light transmission device closer to the second light-transmitting electrode layer (207). A first electric field with a first waveform is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), causing the charged pigment particles to move toward the one or more wells (217b) in the case of the device according to the first embodiment, or to move toward the one or more wells (217b) and the channel in the case of the device according to the second embodiment, thereby causing the variable light transmission device to switch to an on optical state. A second electric field is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207) with a second waveform, causing the charged pigment particles to move toward the first light-transmitting electrode layer (202), wherein the closed optical state has a lower percentage of transparency than the open optical state.

[0024] The three-dimensional shape of each well (217b) in the protrusion structure of a microcell of the variable light transmission device in the first and second embodiments can be selected from the group consisting of: (a) a cone or a polygonal pyramid, the bottom surface of which contacts the top plane (229), and the top of which contacts the inner surface (211) of the bottom of the microcell; (b) a cylinder, a frustum, a frustum, or a polygonal prism, the first bottom surface of which, the large bottom surface of which, the large bottom surface of which, or the first bottom surface of which contacts the top plane (229), and the second bottom surface of which, the small bottom surface of which, the large bottom surface of which, or the small bottom surface of which contacts the top plane (217b), contacts the top plane (229), and the second bottom surface of which, the small bottom surface of which, the large bottom surface of which, or the small bottom surface of which contacts the top plane (217b), contacts the top plane (217b); and the third bottom surface of which, the fourth bottom surface of which contacts the top plane (217b); and the fifth bottom surface of which, the sixth bottom surface of which contacts the top plane (217b); and the sixth bottom surface of which, the seventh bottom surface of which contacts the top plane (217b); and the seventh bottom surface of which, the eighth bottom surface of which contacts the top plane (217b); and the eighth bottom surface of which, the ninth bottom surface of which contacts the top plane (217b); and the tenth bottom surface of which, the truncation ... (c) A cylinder or a first frustum is located on a cone or a second cone, the first bottom surface of the cylinder is in contact with the top plane (229), the second bottom surface of the cylinder is in contact with the bottom surface of the cone or the large bottom surface of the frustum, and the top surface of the cone or the small bottom surface of the frustum is in contact with the inner surface of the bottom of the microcell; (d) A polygonal prism or a first frustum is located on a polygonal pyramid or a second polygonal pyramid, the first bottom surface of the polygonal prism or the large bottom surface of the first frustum is in contact with the top plane (229), the second bottom surface of the polygonal prism or the small bottom surface of the first frustum is in contact with the inner surface of the bottom of the microcell; The bottom surface of the body or the large bottom surface of the second polygonal pyramid is in contact with the top surface of the pyramid or the small bottom surface of the second polygonal pyramid, and the top surface of the pyramid or the small bottom surface of the second polygonal pyramid is in contact with the inner surface of the cell bottom, wherein the first and second bottom surfaces of the polygonal prism, the large and small bottom surfaces of the first polygonal pyramid, the bottom surface of the pyramid and the large and small bottom surfaces of the second polygonal pyramid have the same number of sides; (e) A first polygonal pyramid is located on a polygonal pyramid or a second polygonal pyramid or a polygonal prism, the large bottom surface of the first polygonal pyramid is in contact with the top surface plane (229), the small bottom surface of the first polygonal pyramid is in contact with the bottom surface of the pyramid or the large bottom surface of the second polygonal pyramid or the first bottom surface of the polygonal prism, and the top surface of the pyramid or the small bottom surface of the second polygonal pyramid is in contact with the inner surface of the cell bottom. The small base of the second frustum or the second base of the prism is in contact with the inner surface of the bottom of the microcell, wherein the large and small bases of the first frustum, the large and small bases of the second frustum, the bottom of the pyramid, and the first and second bases of the prism have the same number of sides; (f) A first frustum is located on a cone, a second frustum, or a cylinder, the large base of the first frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the bottom surface of the cone, the large base of the second frustum, or the first bottom surface of the cylinder, and the top of the cone, the small base of the second frustum, or the second bottom surface of the cylinder is in contact with the inner surface of the bottom of the microcell;(g) A first cylinder is located on a first truncated cone, the first truncated cone being located on a cone, a second truncated cone, or a second cylinder, the first bottom surface of the first cylinder contacting the top plane (229), the second bottom surface of the first cylinder contacting the large bottom surface of the first truncated cone, the small bottom surface of the first truncated cone contacting the bottom surface of the cone, the large bottom surface of the second truncated cone, or the first bottom surface of the second cylinder, and the top surface of the cone, the small bottom surface of the second truncated cone, or the second bottom surface of the second cylinder contacting the inner surface of the cell bottom; (h) A first truncated cone is located on a cylinder or a second truncated cone. Above, the cylinder or the second frustum is located on a cone or a third frustum, the large base of the first frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the first bottom surface of the cylinder or the large base of the second frustum, the second bottom surface of the cylinder or the small base of the second frustum is in contact with the bottom surface of the cone or the large base of the third frustum, and the top of the cone or the small base of the third frustum is in contact with the inner surface of the bottom of the microcell; (i) a first frustum is located on a second frustum, the second frustum is located on a cone or a third frustum or a cylinder, the first cylinder The large base of the frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the large base of the second frustum, the small base of the second frustum is in contact with the bottom surface of the cone or the large base of the third frustum or the first bottom surface of the cylinder, and the top of the cone or the small base of the third frustum or the second bottom surface of the cylinder is in contact with the inner surface of the bottom of the microcell; (j) a first polygonal frustum is located on a pyramidal prism or a second polygonal frustum, the pyramidal prism or the second polygonal frustum is located on a polygonal pyramid or a third polygonal frustum, the large base of the first polygonal frustum is in contact with the top plane (229). 9) Contact: The small base of the first truncated pyramid is in contact with the first base of the pyramidal prism or the large base of the second truncated pyramid; the second base of the pyramidal prism or the small base of the second truncated pyramid is in contact with the base of the pyramid or the large base of the third truncated pyramid; and the apex of the pyramid or the small base of the third truncated pyramid is in contact with the inner surface of the bottom of the microcell. The large and small bases of the first truncated pyramid, the first and second bases of the pyramidal prism, the large and small bases of the second truncated pyramid, the base of the pyramid, and the large and small bases of the third truncated pyramid have the same number of sides.And (k) a first polyhedral frustum is located on a second polyhedral frustum, which is located on a polyhedral pyramid, a third polyhedral frustum, or a polyhedral prism. The large base of the first polyhedral frustum is in contact with the apex plane (229), the small base of the first polyhedral frustum is in contact with the large base of the second polyhedral frustum, the small base of the second polyhedral frustum is in contact with the base of the polyhedral pyramid, the large base of the third polyhedral frustum, or the first base of the polyhedral prism, and the apex of the polyhedral pyramid, the small base of the third polyhedral frustum, or the second base of the polyhedral prism is in contact with the inner surface of the cell bottom. The large and small bases of the first, second, and third polyhedral frustums, the first and second bases of the polyhedral prism, and the base of the polyhedral pyramid have the same number of sides.

[0025] The three-dimensional shape of the protrusion structure (217) of a microcell of the variable light transmission device in the first and second embodiments can be selected from the group consisting of: (a) a cylinder, the first bottom surface of which is the protrusion bottom surface (218), and the second bottom surface of which is in contact with the top surface (229); (b) a polygonal prism, the first bottom surface of which is the protrusion bottom surface (218), and the second bottom surface of which is in contact with the top surface (229); 229) Contact, the first bottom surface and the second bottom surface each have 3 to 20 sides; (c) A frustum of a cone, the large bottom surface of the frustum being the convex bottom surface (218), and the small bottom surface of the frustum contacting the apex plane (229); (d) A frustum of a polygon, the large bottom surface of the frustum being the convex bottom surface (218), the small bottom surface of the frustum contacting the apex plane (229), the large bottom surface and the small bottom surface of the frustum each having the same Number of sides (3 to 20 sides); (e) a first frustum of a cone located on a cylinder or a second frustum of a cone, the first base of the cylinder or the large base of the second frustum of a cone being the raised base (218), the second base of the cylinder or the small base of the second frustum of a cone contacting the large base of the first frustum of a cone, and the small base of the first frustum of a cone contacting the top plane (229); and (f) a first frustum of a polygon located on a polygonal cylinder or a second frustum of a polygon. The first bottom surface of the polygonal prism or the large bottom surface of the second polygonal frustum is the raised bottom surface (218). The second bottom surface of the polygonal prism or the small bottom surface of the second polygonal frustum is in contact with the large bottom surface of the first polygonal frustum, and the small bottom surface of the first polygonal frustum is in contact with the top plane (229). The large and small bottom surfaces of the first and second polygonal frustums and the first and second bottom surfaces of the polygonal prism each have the same number of sides (3 to 20 sides).

[0026] According to the first and second embodiments, the microcell opening (205) of each of the plurality of microcells (204) in the microcell layer (203) of the variable light transmission device has a shape, the shape of the microcell opening (205) is selected from the group consisting of: a circle, an ellipse, a square, a rectangle and a polygon, the polygon having 5 to 12 sides.

[0027] Each of the plurality of microcells (204) in the microcell layer (203) of the variable light transmission device according to the first and second embodiments can have a length of 400 micrometers to 800 micrometers and a height of 20 micrometers to 100 micrometers.

[0028] The variable light transmission device according to the first and second embodiments may include: (i) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the sealing layer (206); (ii) a second adhesive layer disposed between the microcell layer (203) and the second light-transmitting electrode layer (207); or (iii) the adhesive layer and the second adhesive layer.

[0029] The variable light transmission device according to the first and second embodiments may include a light blocking layer (230) disposed between the upper surface (214) of the microcell wall and the sealing layer (206). The light blocking layer (230) contains a light-absorbing pigment, and the light-absorbing pigment of the light blocking layer (230) may be black.

[0030] The charged pigment particles (223) of the electrophoretic medium (209) of the variable light transmission device according to the first and second embodiments can absorb light.

[0031] When the second electric field is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207) of the variable light transmission device according to the first and second embodiments, the charged pigment particles (223) move toward the first light-transmitting electrode layer (202) at a speed that may have a lateral component.

[0032] A first electric field with a first waveform is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207) of the variable light transmission device according to the first and second embodiments, causing the charged pigment particles to move toward one or more wells (217b), thereby causing the variable light transmission device to switch to an on optical state. The first electric field may have a net positive pulse or a net negative pulse. The second waveform may include an AC waveform with a duty cycle of 5% to 45%. The second waveform may include a DC bias waveform, which is formed by superimposing a DC voltage component and an AC waveform.

[0033] The variable light transmission device according to the second embodiment may include a microcell having a protrusion structure comprising 1 to 3 wells, 1 to 5 wells, 1 to 10 wells, 1 to 15 wells, 1 to 20 wells, 1 to 30 wells, 2 to 5 wells, 2 to 10 wells, 2 to 15 wells, 2 to 20 wells, 2 to 30 wells, 5 to 25 wells, or 5 to 30 wells. The variable light transmission device according to the second embodiment may include a microcell layer, each of the plurality of microcells in the microcell layer having a protrusion structure, the protrusion structure including 1 to 3 wells, 1 to 5 wells, 1 to 10 wells, 1 to 15 wells, 1 to 20 wells, 1 to 30 wells, 2 to 5 wells, 2 to 10 wells, 2 to 15 wells, 2 to 20 wells, 2 to 30 wells, 5 to 25 wells, or 5 to 30 wells.

[0034] The variable light transmission device according to the first embodiment may include a microcell having a protrusion structure comprising 1 to 3 wells, 1 to 5 wells, 1 to 10 wells, 1 to 15 wells, 1 to 20 wells, 1 to 30 wells, 1 to 35 wells, 1 to 39 wells, 10 to 20 wells, 10 to 39 wells, 2 to 5 wells, 2 to 10 wells, 2 to 15 wells, 2 to 20 wells, 2 to 30 wells, 2 to 35 wells, 2 to 39 wells, 10 to 25 wells, 10 to 30 wells, 10 to 39 wells, 15 to 39 wells, or 20 to 39 wells. The variable light transmission device according to the first embodiment may include a microcell layer, each of the plurality of microcells in the microcell layer having a protrusion structure, the protrusion structure including 1 to 3 wells, 1 to 5 wells, 1 to 10 wells, 1 to 15 wells, 1 to 20 wells, 1 to 30 wells, 1 to 35 wells, 1 to 39 wells, 10 to 20 wells, 10 to 39 wells, 2 to 5 wells, 2 to 10 wells, 2 to 15 wells, 2 to 20 wells, 2 to 30 wells, 2 to 35 wells, 2 to 39 wells, 10 to 25 wells, 10 to 30 wells, 10 to 39 wells, 15 to 39 wells, or 20 to 39 wells.

[0035] According to the second embodiment, the channel of the variable light transmission device can have a width of 5 micrometers to 30 micrometers, 10 micrometers to 30 micrometers, 15 micrometers to 20 micrometers, or 10 micrometers to 20 micrometers.

[0036] The well of the variable light transmission device according to the first and second embodiments can have a width of 5 micrometers to 30 micrometers, 5 micrometers to 20 micrometers, 10 micrometers to 20 micrometers, or 10 micrometers to 25 micrometers.

[0037] According to the second embodiment, the inner surface (213) of the cell wall of a microcell of the variable light transmission device and the inner surface (211) of the bottom of the microcell can form an angle (φ), which is 90 to 120 degrees. Simple Explanation of the Diagram

[0038] Figure 1 is a diagram showing cylindrical particles in a liquid under the action of an applied electric field and the resultant force acting on the particles; Figures 2A and 2B illustrate an example side view of a microcell of the variable light transmission device according to the first embodiment of the present invention; Figures 3A and 3B illustrate an example side view of a microcell of the variable light transmission device according to the first embodiment of the present invention; Figures 4A, 4B, 4C, and 4D illustrate side views of various well examples; Figures 5A and 5B illustrate an example side view of a microcell of the variable light transmission device according to the second embodiment of the present invention; Figure 5C is a perspective view of the microcell of the variable light transmission device according to the second embodiment, wherein the microcell has 22 wells; Figures 6A and 6B illustrate an example side view of a microcell of the variable light transmission device according to the second embodiment of the present invention; Figure 7 illustrates a partial side view of one example of a variable light transmission device according to a second embodiment of the present invention; the side view includes four microcells; Figures 8A to 8F are side views illustrating examples of the raised structure of the microcells in the variable light transmission device of the present invention; Figure 9 illustrates a side view of an example of a microcell of the variable light transmission device of the second embodiment in the optically activated state; Figure 10 illustrates an example side view of a microcell of the variable light transmission device of the second embodiment in a closed optical state; Figure 11 shows an example of a second waveform that can be applied to the variable light transmission device of the present invention to achieve a closed optical state; this example includes a DC unbalanced waveform, which includes an AC waveform with a duty cycle of more than 50%. Figure 12 shows another example of a second waveform that can be applied to the variable light transmission device of the present invention to achieve a closed optical state; this waveform is a superposition of a DC voltage component and an AC waveform. Figure 13 illustrates the force exerted by a charged pigment particle on the surface of a conical protrusion of the variable light transmission device of the present invention; Figure 14 illustrates a side view of an example microcell of the variable light transmission device of the second embodiment; this example microcell includes a light-blocking layer located on the upper surface of the microcell wall; Figure 15 illustrates a side view of an example microcell of the variable light transmission device of the second embodiment; in this example, the inner surface of the microcell wall and the bottom surface of the microcell form an angle (φ) greater than 90 degrees; Figure 16 illustrates an example side view of a microcell of the variable light transmission device according to the second embodiment; this microcell includes a protruding structure in which a first truncated cone is located on a second truncated cone; the slope of the first truncated cone is less than the slope of the second truncated cone; Figure 17 illustrates a side view of an example microcell of the variable light transmission device according to the second embodiment; this microcell includes a protruding structure in which a first truncated cone is located on a second truncated cone; the slope of the first truncated cone is less than the slope of the second truncated cone; the inner surface of the microcell wall and the bottom surface of this example microcell form an angle (φ) greater than 90 degrees; Figure 18A illustrates a top view of a portion of a variable light transmission device having a plurality of microcells, each of which has a hexagonal inner base perimeter and an outer base perimeter; Figure 18B shows the Fraunhofer diffraction patterns formed by the circular apertures and the hexagonal apertures of the device. A portion of the multiple microcells of the device is shown in Figure 18A. Figure 19A illustrates an example side view of a microcell of the variable light transmission device of the first embodiment. This microcell does not include a channel and has a cylindrical protrusion structure. Figure 19B shows the Fraunhofer diffraction pattern formed by the variable light transmission device, the microcells of which are shown in Figure 19A; Figure 20A illustrates an example side view of a microcell of the variable light transmission device of the second embodiment; this microcell is a geometric shape consisting of a frustum of a cone situated on a cylinder; Figure 20B illustrates a top view of an example microcell of a variable light transmission device, while a side view of the microcell of the variable light transmission device is shown in Figure 20A; and Figure 21 shows the Fraunhofer diffraction pattern formed by the variable light transmission device, with the microcells of the variable light transmission device shown in Figure 20A (circular aperture). Implementation

[0039] As used herein, a "variable light transmission device" is a device that includes an electrophoretic medium, wherein the amount of light transmitted through the device can be controlled by applying an electric field over the entire electrophoretic medium.

[0040] "The first outer surface of the variable light transmission device" and "the second outer surface of the variable light transmission device" are the outer surfaces of the device that are parallel to the first and second light-transmitting electrode layers, respectively. As used herein, "outer surface" refers only to the main surface on the viewing side of the variable light transmission device, and not to the smaller surfaces surrounding the device.

[0041] The "first exposed inner surface of the microcell bottom" refers to the portion of the inner surface of the microcell bottom of the variable light transmission device in the second embodiment that contacts the channel of the variable light transmission device. This channel is filled with an electrophoretic medium. Therefore, the first exposed inner surface of the microcell bottom is in contact with the electrophoretic medium of the microcell. Conversely, the "unexposed inner surface of the microcell bottom" is not in contact with the electrophoretic medium of the microcell. The unexposed inner surface of the microcell bottom is the portion of the inner surface of the microcell bottom of the variable light transmission device in both the first and second embodiments that contacts the bottom surface (218a) of the protruding structural entity portion. The "second exposed inner surface of the microcell bottom" is the portion of the inner surface of the microcell bottom of the variable light transmission device in the second embodiment that contacts the protruding structural hole of the variable light transmission device. The protruding structure is also filled with an electrophoretic medium. Therefore, the second exposed inner surface of the microcell bottom is in contact with the electrophoretic medium of the microcell.

[0042] When this text uses the phrase "in contact with the electrophoretic medium" (referring to the surface within the microcell), it is assumed that the entire usable volume of the microcell is filled with the electrophoretic medium. Usable volume is the volume of the microcell not occupied by the physical medium.

[0043] The "transparency percentage of the variable light transmission device" (%T) at a certain location of the device is given by Formula 1. Therefore, the "transparency percentage of the variable light transmission device" (%T) at a certain location of the device is the ratio of the intensity (I) of light transmitted through the variable light transmission device and emitted from a certain location on the second outer surface of the variable light transmission device to the intensity (Io) of light entering the variable light transmission device from a certain location on the first outer surface of the variable light transmission device, multiplied by 100; the location of the second outer surface is symmetrical to the location of the first outer surface with respect to a plane system, which is located at equal distances between the first and second light-transmitting electrode layers. %T = (I / Io) × 100 (Formula 1)

[0044] The distance between a point and a plane is the shortest perpendicular distance from that point to the plane. The shortest distance from a point to a plane is the length of the perpendicular line parallel to the normal vector from the given point to the given plane.

[0045] The distance between two planes in three-dimensional space is the shortest distance between those two planes. It is the shortest distance between any point on one plane and any point on the other plane.

[0046] The term "cone" as used in this article includes cones with a circular or elliptical base.

[0047] A frustum is the base of a cone or polygon obtained by cutting off the top part with a plane parallel to the base. Because it has no top but two parallel bases, it is also called a flat-topped cone or pyramid.

[0048] The term "frustum" as used in this article includes frustums of cones having a circular or elliptical base.

[0049] The slope of a cone is defined as an angle having: (a) a vertex (A) on the circumference of the base of the cone; (b) a first arm, which is a line connecting point A (vertex) to the center C of the base of the cone; and (c) a second arm, which is a line connecting point A (vertex) to the apex of the cone.

[0050] The slope of a frustum is defined as an angle having: (a) a vertex (A) on the circumference of the base (large) surface of the frustum; (b) a first arm, which is a line connecting point (A) (the vertex) and the center C of the base of the frustum; and (c) a second arm, which is the intersection of the side surface of the frustum and a plane containing the line segment AC, which is perpendicular to the base of the frustum.

[0051] The slope of a polygonal pyramid is defined as an angle having: (a) a vertex (A) around the base of the pyramid; (b) a first arm, a line connecting point A (vertex) to the center of the base of the pyramid; and (c) a second arm, a line connecting point A (vertex) to the vertex of the pyramid. The slope of a frustum is defined as an angle having: (a) a vertex (A) around the base (large) surface of the frustum; (b) a first arm, a line connecting point A (vertex) to the center of the base of the frustum; and (c) a second arm, the intersection of the side surface of the frustum and a plane containing line segment AC, this plane being perpendicular to the base of the frustum.

[0052] The term "charged pigment particle" can refer to a charged pigment particle with or without any polymer material on its surface. As used herein, the term "charged pigment particle" is synonymous with "electrophoretic particle".

[0053] The "inner surface of the microcell wall" refers to the surface of the microcell wall that is in contact with the electrophoretic medium of the microcell. As mentioned above, this definition assumes that the entire usable volume of the microcell is filled with the electrophoretic medium.

[0054] The "upper surface of the microcell wall" refers to the surface of the microcell wall that is in contact with the sealing layer of the microcell. In the case where a light-blocking layer exists on the upper surface of the microcell wall, the light-blocking layer is positioned between the upper surface of the microcell wall and the sealing layer.

[0055] "The length of the cell" is the longest distance between any point on the cell opening (205) and any other point on the cell opening (205). "The height of the cell" is the distance between the plane containing the cell opening (205) and the plane containing the inner surface (211) of the cell bottom.

[0056] The "channel bottom width" (216w) is the minimum distance between the inner bottom perimeter (224) and the outer bottom perimeter (225) of the channel of the microcell.

[0057] As used herein, a surface on plane A is in contact with another surface on plane B, meaning that the two planes are parallel and all points are in contact with each other. For example, when the bottom surface A of a first geometry is in contact with the bottom surface B of a second geometry, the plane containing the surface of bottom surface A is parallel to the plane containing the surface of bottom surface B, and the two planes are in contact with each other.

[0058] The term "DC-balanced waveform" or "DC-balanced drive waveform" applied to a pixel is a drive waveform in which the drive voltage applied to the pixel is substantially zero when integrated over the entire application period of the waveform. DC balancing can be achieved by balancing each stage of the waveform, that is, selecting a first positive voltage such that integration over the subsequent negative voltage results in zero or substantially zero. If the waveform is not DC-balanced, it is called a "DC-unbalanced waveform" or "DC-unbalanced drive waveform." The drive waveform applied to a pixel may have a DC-unbalanced portion and at least one additional pulse with opposite pulses to ensure that the entire waveform applied to the pixel is DC-balanced. This additional pulse may be applied before the DC-unbalanced portion of the waveform (pre-pulse). Typical examples of DC-unbalanced waveforms include (a) an AC square wave or sine wave with a duty cycle of less than (or greater than) 50%, and (b) an AC square wave or sine wave with DC bias.

[0059] The term "pulse" refers to the integral of voltage with respect to time. That is, for a waveform pulse of voltage V with an applied time t, the pulse is V × t. If the polarity of voltage V is positive, the pulse will be positive; if the polarity of voltage V is negative, the pulse will be negative.

[0060] The term "net positive pulse" in waveform refers to the phenomenon where negatively charged pigment particles are attracted to and move toward the first light-transmitting electrode layer during the application of the waveform.

[0061] The term "lateral component of velocity" related to the motion of charged pigment particles in the microcells of the variable light transmission device of the present invention refers to the velocity in the horizontal direction. For this definition, we assume that the velocity of a charged particle is the vector obtained by adding the vectors of the horizontal velocity (Vt) and the vertical velocity (Vv), and that, in the case of charged pigment particles moving within the electrophoretic microcell, the vertical direction is from the first phototransmitting electrode layer to the second phototransmitting electrode layer or from the second phototransmitting electrode layer to the first phototransmitting electrode layer. In the same system, the horizontal direction of the movement of charged pigment particles within the electrophoretic microcell is from one side of the microcell wall to the other side of the microcell wall, parallel to the first phototransmitting electrode layer. Therefore, the statement regarding the velocities of a plurality of charged pigment particles that "the velocity of the charged pigment particles has a lateral component" means that the magnitude of the velocity in the horizontal direction is greater than zero.

[0062] The phenomenon of induced charge electroosmosis (ICEO) can be used to laterally move polarizable particles, such as pigment particles, present in an electrophoretic medium. That is, polarizable particles can move parallel to the electrode layer sandwiching the electrophoretic medium. In the presence of an electric field, the particles may experience a force caused by the polarization of the particles (or by the polarization of a conductive coating adsorbed on the particle surface or the electric double layer surrounding the particles). As shown in Figure 1, where cylindrical particles 101 are surrounded by the liquid of the electrophoretic medium in an applied electric field, this force may cause a disturbance in the flow of mobile charges (e.g., ions or charged microparticles) in the electrophoretic medium. This figure is reproduced from the article by Bazant and Squires, J. Fluid Mech., 2004, 509, 217-252.

[0063] Perfectly symmetrical spherical particles experience no net force, but less symmetrical particles experience a force with a component perpendicular to the applied field. The cooperative flow generated by a group of particles, each subject to such a force, results in a "vortex" in the electrophoretic medium containing multiple particles. According to the theory proposed in the Bazant and Squires paper, the maximum velocity u of the vortex for a given particle is approximately represented by equation (1): (Expression 1)

[0064] In Equation 1, the field strength of the E system, the dielectric constant of the solvent of the ε system, the viscosity of the electrophoretic fluid of the η system, the sinusoidal alternating frequency applied by the ω system, and the time scale of the time scale used to establish the screening charge layer through the movement of solvent-borne charges around the charge are represented by Equation (3): (Formula 3)

[0065] In Equation 3, λD represents the Debye shielding length, R represents the particle radius, and D represents the diffusion constant of the charge carrier in the fluid.

[0066] According to Equation 1, as the frequency increases, the value of ω²τ² increases and the maximum velocity of the induced charge flow decreases. Furthermore, for ω²τ² values ​​significantly greater than 1, the maximum vortex velocity is proportional to the square of the ratio E / ω. Regardless of the polarity of the applied electric field, the induced charge flow occurs in the same direction, and therefore can be driven by an alternating field.

[0067] When the electrophoretic medium, as preferred in an electrophoretic display, is contained within microcells, the resulting flow geometry is influenced by the shape of the microcells used. For example, in the simplest case with two parallel electrodes, it has been shown that, using appropriate electric field strength and alternating frequency, the flow can employ a roll structure with periodic intervals corresponding to the gap width between the electrodes.

[0068] The inventors of this invention use a complex microcellular structure formed by an embossing method to manufacture a variable light transmission device. In one example, the embossed structure includes raised structures on the bottom inner surface of each microcell. Figures 2A, 2B, 3A, 3B, and 18 illustrate examples of a first embodiment of the variable light transmission device according to the invention. The first embodiment includes a variable light transmission device containing microcells, wherein the microcells do not contain channels. Figures 5A, 5B, 6A, 6B, 7, 8, 9, 13, 14, 16, 15, 17, and 20 illustrate examples of a second embodiment of the variable light transmission device according to the invention. The second embodiment includes a variable light transmission device containing microcells with channels.

[0069] Figures 2A and 2B illustrate an example side view of a microcell of the variable light transmission device 200 according to the first embodiment. Figures 2A and 2B illustrate cross-sectional (side view) views of the same device. That is, the graphics in Figure 2A are repeated in Figure 2B to facilitate identification of the various parts and components of the device. These graphics only illustrate a portion of the display (not drawn to scale), showing only one microcell among the plurality of microcells of the device. The variable light transmission device 200 sequentially includes a first light-transmitting substrate (201), a first light-transmitting electrode layer (202), a microcell layer (203), a second light-transmitting electrode layer (207), and a second light-transmitting substrate (208). The microcell layer 203 is disposed between the first light-transmitting electrode layer 202, the second light-transmitting electrode layer 207, and the second light-transmitting substrate (208). The microcell layer 203 includes a plurality of microcells (204) and a sealing layer (206). Each of the plurality of microcells (204) comprises an electrophoretic medium (209) containing charged pigment particles and a nonpolar liquid (not shown in Figures 2A and 2B). Each of the plurality of microcells (204) has a microcell opening (205), and a sealing layer (206) spans the microcell openings (205) of the plurality of microcells (204). Each of the plurality of microcells (204) includes a microcell bottom layer (210), a protruding structure (217), and a microcell wall (212), the microcell bottom layer (210) having an inner surface (211) at the bottom of the microcell. The variable light transmission device of the present invention has a first outer surface (250) and a second outer surface (251). The first outer surface (250) is located on the side of the variable light transmission device closer to the first light-transmitting electrode layer (202), while the second outer surface (251) is located on the side of the variable light transmission device closer to the second light-transmitting electrode layer (207).

[0070] The protruding structure (217) of the device in Figures 2A and 2B consists of a protruding structural solid portion (217a) and a well (217b). The protruding structural solid portion (217a) includes a top end (219), a side surface (221), a bottom surface (218), a height (220), and a top plane (229). The bottom surface of the protruding structural solid portion is the surface that contacts the bottom layer (210) of the microcell or is equivalent to the surface that contacts the inner surface (211) of the bottom of the microcell, and is not labeled in Figures 2A and 2B. The top end (219) of the protruding structural solid portion is a point or set of points of the protruding structural solid portion (217a) that is shorter than all other points of the protruding structural solid portion (217a) in distance from the microcell opening (205). The top plane (229) is a plane parallel to the plane of the microcell opening (205) and encompassing the top of the protruding structural solid portion (219). The side surface (221) of the protruding structural solid portion is the surface in contact with the electrophoretic medium (209) of the protruding structural solid portion, excluding the top of the protruding structural solid portion (219). In the case where the top of the protruding structural solid portion (219) is a set of points, this set of points can form a surface that is not part of the side surface (221) of the protruding structural solid portion. Even in the case where the top of the protruding structure is not a surface but only a point or a finite number of points, as in the examples of the devices in Figures 2A and 2B, this point or this finite number of points is not part of the side surface (221) of the protruding structural solid portion according to the definition of the side surface (221) of the protruding structural solid portion. In other words, the total surface in contact with the electrophoretic medium (209) of the protruding structural solid portion is the combination of the surface formed by the side surface (221) of the protruding structural solid portion and the top of the protruding structural solid portion. The height of the protrusion (220) is the distance between the top plane (229) and the bottom plane (218).

[0071] The protruding structure has a three-dimensional shape. In the examples of the devices in Figures 2A and 2B, the three-dimensional shape of the protruding structure is a cylinder. The first base of the cylinder is the protruding base 218, and the second base of the cylinder contacts the top plane 229. The height of the protruding structure is the distance between the protruding base (218) and the top plane 229.

[0072] The well has a three-dimensional shape. The entire volume of the well is filled with an electrophoretic medium (209). The three-dimensional shape of each well in one or more wells (217b) is defined by the space between (i) the top plane (229), (ii) the side surface (221) of the protruding structural solid portion, and (iii) the inner surface (211) of the bottom of the microcell. In the example of the device in Figures 2A and 2B, there is only one well, whose three-dimensional shape consists of two geometric shapes, namely, a first truncated cone located on a second truncated cone. The large base of the first truncated cone contacts the top plane 229; the small base of the first truncated cone contacts the large base of the second truncated cone; and the small base of the second truncated cone contacts the bottom layer 210 of the microcell.

[0073] The microcells shown in Figures 2A and 2B have an inner surface 213 and an upper surface 214 in their cell walls 212. The inner surface 213 is in contact with the electrophoresis medium 209. The upper surface 214 is the surface in contact between the microcell wall 212 and the sealing layer 206.

[0074] In the example of the variable light transmission device 200 in Figures 2A and 2B, the raised structure (the combination of the solid portion 217a and the well 217b) can also be a polygonal prism with 3 to 20 sides. This polygonal prism has two bases: a first base and a second base. The first base contacts the top plane (229), while the second base is the raised base (218). The well 217b of the variable light transmission device 200 can be a first truncated pyramid located on a second truncated pyramid. The first truncated pyramid has a small base and a large base. Similarly, the second truncated pyramid has a small base and a large base. All bases of the first and second truncated pyramids can be polygons with the same number of sides (3 to 20 sides). The large base of the first truncated pyramid contacts the top plane 229. The small base of the first truncated pyramid contacts the large base of the second truncated pyramid. The small base of the second truncated pyramid contacts the inner surface 211 of the cell bottom.

[0075] The variable light transmission device 300 in Figures 3A and 3B has a structure similar to that of the variable light transmission device 200 in Figures 2A and 2B. The only difference relates to the three-dimensional shape of well 217b. Specifically, as in the microcell of the variable light transmission device 200, the protruding structure 217 of the microcell of the variable light transmission device 300 can be a cylinder or a polygonal prism. However, well 217b of the protruding structure 217 of the variable light transmission device 300 is a frustum of a cone located on a cone. The frustum of a cone has a large base and a small base, while the cone has a base and a apex. The large base of the frustum of a cone is part of the apex plane 229. The small base of the frustum of a cone contacts the base of the cone. The apex of the cone in the microcell of the variable light transmission device 300 is part of the protruding base 218, which contacts the inner surface 211 of the bottom of the microcell.

[0076] Figures 4A, 4B, 4C, and 4D illustrate side views of wells 217b with various three-dimensional shapes in the microcells of the variable light transmission device according to the first embodiment. Specifically, Figure 4A illustrates a well with a three-dimensional shape consisting of a first truncated cone located on a second truncated cone or a first polygonal truncated cone located on a second polygonal truncated cone, wherein both the first and second polygonal truncated cones have 3 to 20 sides. The slope of the first truncated cone is less than the slope of the second truncated cone, or the slope of the first polygonal truncated cone is less than the slope of the second polygonal truncated cone. Figure 4B illustrates a well with a three-dimensional shape consisting of a first truncated cone located on a second truncated cone and a second truncated cone located on a cylinder, or a first polygonal truncated cone located on a second polygonal truncated cone and a second polygonal truncated cone located on a polygonal prism, wherein the first, second, and polygonal truncated cones and the polygonal prism have 3 to 20 sides. The slope of the first frustum is less than the slope of the second frustum, or the slope of the first truncated polygon is less than the slope of the second truncated polygon. Figure 4C illustrates a well having a three-dimensional shape formed by the first frustum located on the second frustum and the second frustum located on the third frustum, or the first truncated polygon located on the second truncated polygon and the second truncated polygon located on the third truncated polygon, wherein the first, second, and third truncated polygons have 3 to 20 sides. The slope of the first frustum is less than the slope of the second frustum, and the slope of the second frustum is less than the slope of the third frustum; or the slope of the first truncated polygon is less than the slope of the second truncated polygon, and the slope of the second truncated polygon is less than the slope of the third truncated polygon. Figure 4D illustrates a well having a three-dimensional shape formed by the frustum located on a cone or the truncated polygon located on a polygon, wherein the truncated polygon and the polygonal prism have 3 to 20 sides. The slope of the frustum is less than that of the cone, or the slope of the frustum of a polygon is less than that of the prism. The apex plane 229 is shown in Figures 4A-4D for reference. The slope of the geometry of the wells in the various variable light transmission devices of the first embodiment allows charged electrophoretic pigment particles to aggregate in the wells of the protruding structure, thereby forming the open optical state of the device.

[0077] Figures 5A and 5B illustrate examples of portions of the variable light transmission device 200 according to the second embodiment. Figures 5A and 5B illustrate cross-sectional (side view) views of the same light transmission device. That is, the graphics of Figure 5A are repeated in Figure 5B to facilitate identification of the various parts and components of the device. These graphics only illustrate a portion of the display (not drawn to scale), showing only one of the plurality of microcells of the device. The variable light transmission device 500 sequentially includes a first light-transmitting substrate (201), a first light-transmitting electrode layer (202), a microcell layer (203), a second light-transmitting electrode layer (207), and a second light-transmitting substrate (208). The microcell layer 203 is disposed between the first light-transmitting electrode layer 202 and the second light-transmitting electrode layer 207. The microcell layer 203 includes a plurality of microcells (204) and a sealing layer (206). Each of the plurality of microcells (204) contains an electrophoretic medium (209), which contains charged pigment particles and a non-polar liquid (not shown). Each of the plurality of microcells (204) has a microcell opening (205), and a sealing layer (206) spans the microcell openings (205) of the plurality of microcells (204). Each of the plurality of microcells (204) includes a microcell base layer (210), a channel (215), a protrusion structure (217), and a microcell wall (212). The microcell base layer (210) has a microcell base inner surface (211), which includes an unexposed microcell base inner surface (211a), a first exposed microcell base inner surface (211b), and a second exposed microcell base inner surface (211c). The raised structure (217) has a raised structural solid portion (217a), a well (217b), a side surface (221) of the raised structural solid portion, a raised bottom surface (218), a raised structural solid portion side surface (221), a raised structural solid portion inner surface (221b), a raised structural solid portion outer surface (221a), a raised structural solid portion top (219), a raised top surface, and a raised height (220). The well 217b has a three-dimensional shape with a certain volume, and the entire volume of the well (217b) is filled with an electrophoretic medium (209). The three-dimensional shape of the well is defined by the space between (i) the top plane (229), (ii) the raised structural solid portion inner surface (221b), and (iii) the second exposed microcell bottom inner surface (211c). The raised structural solid portion side surface (221) is the surface of the raised structural solid portion (217a) in contact with the electrophoretic medium.

[0078] The outer surface (221a) of the solid portion of the raised structure is the portion of the side surface (221) of the solid portion of the raised structure that does not contact one or more wells (217b). The outer surface (221b) of the solid portion of the raised structure is the portion of the side surface of the solid portion of the raised structure excluding the inner surface (221b) of the solid portion of the raised structure. The apex (219) of the raised structure is a set of points on the raised structure (217) that are shorter than the distance to the microcell opening (205) than all other points on the raised structure (217). The height of the raised structure (220) is the distance between the apex plane (229) and the bottom surface (218) of the raised structure. The bottom surface (218) of the raised structure is the surface in contact with the solid portion of the raised structure and one or more wells and the bottom layer (210) of the microcell.

[0079] The three-dimensional shape of the protruding structure 217 (a combination of the protruding structure solid portion 217a and one or more wells 217b) of the variable light transmission device 500 in Figures 5A and 5B is a frustum of a cone situated on a cylinder. The frustum of a cone has a small base and a large base. The cylinder has a first base and a second base. The small base of the frustum of a cone is part of the top plane (229). The large base of the frustum of a cone contacts the first base of the cylinder, and the second base of the cylinder contacts the inner surface 211 of the bottom of the microcell.

[0080] The three-dimensional shape of the protruding structure 217 of the variable light transmission device 500 in Figures 5A and 5B can also be a polygonal frustum located on a polygonal prism, the polygonal frustum having 3 to 20 sides, and the polygonal prism having a first base and a second base, both having 3 to 20 sides. The polygonal frustum has a large base and a small base, both of which are polygons with 3 to 20 sides. The small base of the polygonal frustum is part of the top plane (229). The large base of the polygonal frustum contacts the first base of the polygonal prism. The second base of the polygonal prism contacts the inner surface 211 of the bottom of the microcell.

[0081] Well 217b of the variable light transmission device 500 in Figures 5A and 5B can have a three-dimensional shape of a frustum. The frustum has a large base and a small base. The large base of the frustum is part of the top plane (229). The small base of well 217b is in contact with the inner surface 211 of the bottom of the microcell (and part of the raised base). Well 217b of the variable light transmission device 500 in Figures 5A and 5B can also have a three-dimensional shape of a frustum.

[0082] The microcell wall 212 has an inner surface 213 and an upper surface 214. The inner surface 213 is in contact with the electrophoresis medium 209. The upper surface 214 is the surface in contact between the microcell wall 212 and the sealing layer 206.

[0083] The variable light transmission device shown in Figures 5A and 5B has a single microcell containing only one well. Multiple wells can also be contained within a single microcell. Figure 5C illustrates a perspective view of a microcell of such a variable light transmission device according to the second embodiment. The microcell of this device contains 22 wells. Similar devices with microcells containing multiple wells can also be manufactured for the variable light transmission device according to the first embodiment.

[0084] Figures 6A and 6B illustrate another example of a microcell of the variable light transmission device 600 according to a second embodiment of the present invention. Figures 6A and 6B illustrate cross-sectional (side view) views of the same light transmission device. That is, the graphics of Figure 6A are repeated in Figure 6B to facilitate identification of the various parts and components of the device. These graphics show only a portion of the display (not drawn to scale), showing only one microcell among the plurality of microcells of the device. The other microcells exist in the microcell layer of the device.

[0085] The variable light transmission device 600 in Figures 6A and 6B has a similar structure to the variable light transmission device 500 in Figures 5A and 5B. The only difference is the three-dimensional shape of the well. The protruding structure 217 of the variable light transmission device 600 can be a frustum of a cone located on a cylinder. The frustum of a cone has a small base and a large base. The cylinder has a first base and a second base. The small base of the frustum of a cone is part of the top plane (229). The large base of the frustum of a cone contacts the first base of the cylinder. The second base of the cylinder contacts the inner surface 211 of the cell bottom.

[0086] The protruding structure 217 of the variable light transmission device 600 can be a truncated polygon on a polygonal prism. The truncated polygon has a small base and a large base. The polygonal prism has a first base and a second base. The small base of the truncated polygon is part of the top plane (229). The large base of the truncated polygon contacts the first base of the polygonal prism. The second base of the polygonal prism contacts the inner surface 211 of the cell bottom.

[0087] Well 217b of the variable light transmission device 600 in Figures 6A and 6B can have a three-dimensional cone shape. The cone has a base and a apex. The base of the cone is part of the apex plane (229). The apex of the cone contacts the inner surface 211 of the bottom of the microcell. Well 217b of the variable light transmission device 600 in Figures 6A and 6B can also have a three-dimensional polygonal pyramid shape.

[0088] Figure 7 illustrates a side view of a microcell of an example of a variable light transmission device according to a second embodiment of the present invention. The variable light transmission device in Figure 7 is the same as the variable light transmission device 500 in Figures 5A and 5B, but Figure 7 shows a side view of a larger portion of the device, which contains four microcells.

[0089] The variable light transmission device of the second embodiment (examples of which are shown in Figures 5A, 5B, 6A, 6B and 7) has microcells comprising channels and wells. Therefore, charged electrophoretic pigment particles can aggregate in the wells and channels, thereby forming the open optical state of the device.

[0090] Figure 8 illustrates some examples of wells (side views). Specifically, Figure 8A illustrates a side view of a well with a conical or polygonal pyramidal geometry, the polygon having 3 to 20 sides. Figure 8B illustrates a side view of a well that is a cylinder or polygonal prism. Figure 8C illustrates a side view of a well with a frustum of a cone or a frustum of a polygon. Figure 8D illustrates a side view of a well with a cylinder situated on a frustum of a cone or a cylinder situated on a frustum of a polygon. Figure 8E illustrates a side view of a well with a cylinder situated on a frustum of a cone and the frustum of the cone on the cylinder, or a cylinder situated on a frustum of a polygon and the frustum of the polygon on the cylinder. Figure 8F illustrates a side view of a well with a cylinder situated on a first frustum of a cone and the first frustum of a cone on a second frustum, or a cylinder situated on a first frustum of a polygon and the first frustum of the polygon on a second frustum. The base of the aforementioned geometric shape, the frustum of a polygon, has 3 to 20 sides.

[0091] The variable light transmission device of the first and second embodiments of the present invention can switch from an open optical state (transparent state or light-transmitting state) to a closed optical state (opaque state) by applying an electric field between the electrode layers.

[0092] Figures 9 and 10 illustrate the optical state switching of the variable light transmission device 500 (in the second embodiment). When a first electric field with a first waveform is applied between the first transparent electrode layer 202 and the second transparent electrode layer 207, the charged pigment particles 223 move towards the well (217b) and the channel (215) when the polarity of the charged pigment particles 223 is opposite to the voltage polarity of the second transparent electrode layer. If the polarity of the charged pigment particles 223 is opposite to the voltage polarity of the second transparent electrode layer, the charged pigment particles 223 are attracted by the second transparent electrode, and the variable light transmission device switches to an open optical state, which has a higher percentage of transparency than the closed optical state. The open optical state is illustrated in Figure 9, where the charged pigment particles 223 are represented by solid black circles. In this example, the electrophoretic medium contains one type of charged pigment particles 223. In the open optical state, the charged pigment particles 223 are present in the wells of the microcells.

[0093] A second electric field with a second waveform is applied between the first transparent electrode layer 202 and the second transparent electrode layer 207, causing charged pigment particles 223 to move to the first transparent electrode layer 202 at a certain velocity. This results in a closed optical state as shown in FIG. 10. This velocity has a lateral component. Without the lateral component, the closed optical state would not occur because the charged pigment particles 223 would move from the well (open optical state) to the first transparent electrode layer 202, but these charged pigment particles 223 would occupy the area near the center of the microcells in the sealing layer 206. That is, the charged pigment particles 223 would not be distributed across the entire surface of the first transparent electrode layer 202. Therefore, a closed optical state would not be effectively formed because a closed optical state would have relatively high transmittance.

[0094] The above facts indicate that the transition from the closed optical state to the open optical state is easier to achieve because when charged pigment particles collide with the raised surface of the raised structure as they move toward the second transparent electrode layer, the slope of the raised structure will introduce a lateral component to the velocity of the charged pigment particles.

[0095] By applying a first electric field with a first waveform between the first and second light-transmitting electrode layers, charged pigment particles are moved toward the well (and channel), allowing the variable light transmission device to be switched to an open optical state. By applying a second electric field with a second waveform between the first and second light-transmitting electrode layers, charged pigment particles of the first type are moved toward the first light-transmitting electrode layer at a certain velocity, allowing the variable light transmission device to be switched to a closed optical state. This velocity has a transverse component and results in a closed optical state. The second waveform includes a series of at least two positive and negative pulses with net positive or net negative pulses, wherein the closed optical state has a lower percentage of transparency than the open optical state.

[0096] The second waveform can be DC unbalanced. The second waveform may include at least one positive voltage and at least one negative voltage, and the second waveform has a net positive pulse or a net negative pulse. The choice of net positive pulse or net negative pulse depends on the polarity of the charged pigment particles that are to move to a position near the sealing layer of the electrophoretic medium. Specifically, if the closed state involves the movement of negatively charged pigment particles, a net positive pulse is needed to move those particles from the wells and channels towards the first transparent electrode layer. In other words, this movement requires the net effect of the applied voltage to be the attraction of the positive voltage of the first transparent electrode layer relative to the second transparent electrode layer on the negatively charged particles. Conversely, if the closed state involves the movement of positively charged pigment particles, a net negative pulse is needed to move the positively charged pigment particles from the wells and channels near the second transparent electrode layer 207 towards the first transparent electrode layer.

[0097] A closed optical state is achieved by applying a second electric field with a second waveform between the two transparent electrode layers.

[0098] The second waveform may contain an AC waveform with a duty cycle not equal to 50%. An example of a second waveform is illustrated in Figure 11.

[0099] The AC waveform can have positive or negative DC bias. DC bias can be achieved by controlling the waveform's duty cycle. A positive DC bias waveform has a duty cycle greater than 50%. The duty cycle of a positive DC bias waveform may be greater than 55%, greater than 60%, or greater than 65%. The duty cycle of a positive DC bias waveform may be 55% to 95%, 58% to 90%, 60% to 88%, 65% to 85%, or 70% to 80%. Similarly, a negative DC bias waveform has a duty cycle less than 50%. The duty cycle of a negative DC bias waveform may be less than 45%, less than 40%, or less than 35%. The duty cycle of a negative DC bias waveform may be 5% to 45%, 8% to 40%, 10% to 38%, 15% to 35%, or 20% to 30%.

[0100] The waveform shown in the example of Figure 11 includes an AC square wave with two or more periods. Each period may include a first pulse with amplitude V1 applied to time period t1 and a second pulse with amplitude V2 applied to time period t2, where V1 is positive, V2 is negative, and t1 is greater than t2. DC bias is achieved through the difference in time periods when the amplitude of V1 equals the amplitude of V2 (|V1|=|V2|). In the example of Figure 11, a positive DC bias exists because the application time (t1) of the positive voltage V1 is longer than the application time (t2) of the negative voltage V2. A positive DC bias means that if the charged pigment particles in the variable light transmission device are negatively charged, they will move towards the first light-transmitting electrode layer of the device. The duty cycle of the waveform can be calculated using Equation 4. Working period = 100 × (V1·t1) / [(V1·t2) + (V2·t2)] Formula 4

[0101] In the waveform example in Figure 11, the amplitude of V1 can be equal to the amplitude of V2 (|V1|=|V2|), but in general, the amplitudes of V1 and V2 can be different from each other.

[0102] The example drive waveform in Figure 11 is DC unbalanced. However, the waveform shown in Figure 11 can include one or more additional pulses with reverse pulses, which ensures that the overall waveform applied to the pixel is DC balanced. This additional pulse (or multiple additional pulses) can be applied before the DC unbalanced waveform (pre-pulse). Furthermore, the example waveform in Figure 11 is an AC square wave. Other examples of available AC waveforms include sine waves, triangle waves, and sawtooth waves.

[0103] The AC waveform can have an amplitude from 10V to 200V and a frequency from 0.1 to 6000Hz. The AC waveform can have an amplitude from 15V to 180V, from 20V to 160V, from 25V to 150V, or from 30V to 140V. The AC waveform can have a frequency from 0.5Hz to 5000Hz, from 1Hz to 4000Hz, from 5Hz to 3000Hz, from 10Hz to 2000Hz, from 15Hz to 1000Hz, from 20Hz to 800Hz, or from 25 to 600Hz. The ratio of the AC waveform frequency to the weight percentage of the charge control agent in the electrophoretic medium can be from 400Hz to 2000Hz.

[0104] The second waveform can include a waveform formed by the superposition of a DC voltage component and an AC waveform. An example of a second waveform is illustrated in Figure 12.

[0105] The waveform in Figure 12 has a net negative pulse due to the DC bias (Ved). Although the period for which the positive pulse is applied (t3) is equal to the period for which the negative pulse is applied (t4), the DC bias is achieved by the difference in pulse amplitude. Specifically, the amplitude of the positive pulse V3 is smaller than the amplitude of the negative pulse V4. This is caused by the DC voltage component Vd of the waveform. That is, the waveform shown in Figure 12 has a DC bias.

[0106] The example of the drive waveform in Figure 12 is a DC unbalanced waveform. However, one or more additional pulses with opposite pulses can be included in the waveform of Figure 12, which ensures that the overall waveform applied to the pixel is DC balanced. This additional pulse (or these additional pulses) can be applied before the DC unbalanced waveform (pre-pulse). Additionally, the waveform in Figure 12 is a real AC square wave. Other examples of AC waveforms that can be used include sine waves, triangular waves, and sawtooth waves.

[0107] The AC waveform can have an amplitude from 10V to 200V and a frequency from 0.1 to 6000Hz. The AC waveform can have an amplitude from 15V to 180V, from 20V to 160V, from 25V to 150V, or from 30V to 140V. The AC waveform can have a frequency from 0.5Hz to 5000Hz, from 1Hz to 4000Hz, from 5Hz to 3000Hz, from 10Hz to 2000Hz, from 15Hz to 1000Hz, from 20Hz to 800Hz, or from 25Hz to 600Hz. The ratio of the AC waveform frequency to the weight percentage of the charge control agent in the electrophoretic medium can be from 400Hz to 2000Hz.

[0108] In cases where the kinematic coefficient of charge (ICEO) of the pigment particles is relatively low, even when the device is driven using a DC-balanced AC waveform, the protruding structural solid portion (217a) of the microcell contributes to the efficient operation of the variable light transmission device. As shown in Figure 13, in an example of a protruding structure containing a well with a surface of a certain slope, any charged pigment particle located on the surface will be subject to a net force that causes them to move upward. Figure 13 shows charged pigment particles 223 in contact with the well in electric field 602. In this case, the ICEO flow is indicated by the curved arrows, and the ICEO flow is more constrained on the "uphill" side of the cone compared to the "downhill" side. This exerts a force on the particles as indicated by the dashed horizontal arrows. There will be a counterforce perpendicular to the cone, forcing the particles upward. By appropriately selecting the AC field and frequency, the particles can be moved out of the well. If the geometry of the channel includes surfaces with similar slopes, the same concept applies to particles located in the channel.

[0109] As shown in Figure 14, the microcells of the variable light transmission device (550) of the present invention may also include a light-blocking layer 230. The light-blocking layer 230 is disposed between the upper surface of the microcell and the sealing layer 206. The light-blocking layer 230 may contain a light-absorbing pigment. The light-absorbing pigment of the light-blocking layer may be black. The inventors of the present invention have discovered that the light-blocking layer 230 helps improve the closed state by increasing the opacity of the device, which may be caused by partially translucent wall material. The light-blocking layer 230 may be conductive, which facilitates device switching.

[0110] Figure 15 also illustrates the variable light transmission device (560) of the present invention, which includes a first light-transmitting substrate 201, a first light-transmitting electrode layer 202, a microcell layer comprising a plurality of microcells and a sealing layer 206 (only one microcell is shown here), a second light-transmitting electrode layer 207, and a second light-transmitting substrate 208. Each microcell includes a microcell wall 212, a channel 215, a raised structural solid portion 217a, a well 217b, and a microcell bottom layer 210. In the microcell of the variable light transmission device of Figure 15, the inner surface (213) of the microcell wall and the inner surface (211) of the microcell bottom form an angle (φ) greater than 90 degrees. The inventors of the present invention have found that such a structure significantly facilitates the embossing process for manufacturing a plurality of microcells because the embossing tool can be easily removed without damaging the microcell wall. The angle φ can be 90 to 120 degrees, 93 to 117 degrees, 95 to 115 degrees, 98 to 118 degrees, or 100 to 115 degrees.

[0111] Figure 16 shows an element that aids in the manufacture of this device, illustrating the variable light transmission device (580) of the present invention. The device includes a first light-transmitting substrate 201, a first light-transmitting electrode layer 202, a microcell layer comprising a plurality of microcells and a sealing layer 206 (only one microcell is shown here), a second light-transmitting electrode layer 207, and a second light-transmitting substrate 208. Each microcell includes a microcell wall 212, a protrusion structure 217, and a microcell bottom layer 210. The protrusion structure 217 is a geometry where a first frustum is located on a second frustum. The first frustum has a first slope (θ1), and the second frustum has a second slope (θ2). The second slope (θ2) is greater than the first slope (θ1), and the difference between the second slope (θ2) and the first slope (θ1) is 1 to 25 degrees, 1 to 30 degrees, 2 to 20 degrees, 2 to 15 degrees, 2 to 12 degrees, 2 to 9 degrees, 2 to 8 degrees, 3 to 8 degrees, or 4 to 8 degrees.

[0112] Figure 17 illustrates another variable light transmission device (590) of the present invention, which simplifies the device manufacturing process. The variable light transmission device includes a first light-transmitting substrate 201, a first light-transmitting electrode layer 202, a microcell layer comprising a plurality of microcells and a sealing layer 206 (only one microcell is shown here), a second light-transmitting electrode layer 207, and a second light-transmitting substrate 208. Each microcell includes a microcell wall 212, a protrusion structure 217, and a microcell bottom layer 210. This protrusion structure has a structure similar to that of the protrusion structure in Figure 16, wherein the slope θ2 (second slope) of the second truncated cone is greater than the slope θ1 (first slope) of the first truncated cone. The difference between the second slope (θ2) and the first slope (θ1) is 1 to 25 degrees, 1 to 30 degrees, 2 to 20 degrees, 2 to 15 degrees, 2 to 12 degrees, 2 to 9 degrees, 2 to 8 degrees, 3 to 8 degrees, or 4 to 8 degrees. Furthermore, in the device of Figure 17, the inner surface of the microcell wall (213) and the inner surface of the microcell base (211) form an angle (φ) greater than 90 degrees. The angle φ can be 90 to 120 degrees, 93 to 117 degrees, 95 to 115 degrees, 98 to 118 degrees, or 100 to 115 degrees.

[0113] When the variable light transmission device is in the open optical state, the light-absorbing charged pigment particles reside only in a portion of each microcell (e.g., in the channel). One problem encountered is the diffraction pattern observable within the field of view. This diffraction pattern, called the Fraunhofer diffraction pattern, can be distracting to the viewer. It forms when light, for example, from a small object in a dark environment or specularly reflected sunlight from a bright environment, passes through the variable light transmission device in the open optical state.

[0114] Figure 18A shows a diffraction pattern formed by a hexagonal aperture. The diffraction pattern in Figure 18B contains a highly visible linear component, where the light intensity gradually decreases as the linear component moves away from the center of the light pattern. This diffraction pattern is formed by a variable light transmission device (as shown in Figure 18A) having microcells containing a solid portion of a conical protrusion structure and hexagonal channels; the protrusion structure of this variable light transmission device has no wells.

[0115] In contrast, Figure 19B shows the diffraction pattern formed by the variable light transmission device 350 shown in Figure 19A. The variable light transmission device 350 sequentially includes a first light-transmitting substrate 201, a first light-transmitting electrode layer 202, a microcell layer 203, a second light-transmitting electrode layer 207, and a second light-transmitting substrate 208. The microcell layer 203 comprises a plurality of microcells and a sealing layer 206. Each of the plurality of microcells includes a microcell bottom layer 210, a protrusion structure, and a microcell wall 212. The protrusion structure includes a protrusion structure solid portion 217a and a well 217b. The protrusion structure has a top plane 229. The protrusion structure of the variable light transmission device 350 in Figure 19A is a cylinder with a first bottom surface and a second bottom surface, wherein the first bottom surface is part of the top plane 229, and the second bottom surface contacts the inner surface 211 of the bottom of the microcell. The well 217b of the variable light transmission device 350 is a frustum of a cone located on the cylinder. The frustum has a large base and a small base, while the cylinder has a first base and a second base. The large base of the frustum is part of the apex 229. The small base of the frustum contacts the first base of the cylinder. The second base of the cylinder contacts the inner surface 211 of the cell bottom. The diffraction pattern of the variable light transmission device 350 from Figure 19A does not have a highly visible linear component like the diffraction pattern of the variable light transmission device from Figure 19B.

[0116] Figure 21 shows the diffraction pattern formed by the variable light transmission device 650 shown in Figures 20A and 20B. Figure 20A is a side view of a portion of the variable light transmission device 650, and Figure 20B is a top view of a portion of the variable light transmission device 650. The variable light transmission device 650 sequentially includes a first light-transmitting substrate 201, a first light-transmitting electrode layer 202, a microcell layer 203, a second light-transmitting electrode layer 207, and a second light-transmitting substrate 208. The microcell layer 203 includes a plurality of microcells and a sealing layer 206. Each of the plurality of microcells includes a microcell bottom layer 210, a protrusion structure, a channel 215, and a microcell wall 212. The protrusion structure includes a protrusion structure solid portion 217a and a well 217b. The protrusion structure has a top plane 229. The protrusion structure of the variable light transmission device 650 in Figures 20A and 20B is a frustum of a cone located on a cylinder.

[0117] Therefore, the variable light transmission device of the first and second embodiments of the present invention provides improved optical performance when the optical state is turned on.

[0118] Terms:

[0119] Clause 1: A variable light transmission device (200) includes: First transparent electrode layer (202); A second light-transmitting electrode layer (207); and A microcell layer (203) is disposed between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207). The microcell layer (203) includes a plurality of microcells (204) and a sealing layer (206). Each microcell in the plurality of microcells (204) contains an electrophoretic medium (209), which contains charged pigment particles and a nonpolar liquid. Each microcell in the plurality of microcells (204) has a microcell opening (205). The sealing layer (206) spans the microcell openings (205) of the plurality of microcells (204). Each microcell's sealing layer (206) has an upper surface and a lower surface, the lower surface being in contact with the electrophoretic medium (209), and the upper surface being in contact with (i) the first light-transmitting electrode layer (202) or (ii) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the upper surface of the sealing layer (206); Each of the plurality of microcells (204) includes a microcell base layer (210), a protrusion structure (217) and a microcell wall (212), wherein the microcell base layer (210) has a microcell bottom inner surface (211); The protruding structure (217) consists of a protruding structural solid portion (217a) and one or more wells (217b). The protruding structure (217) has a protruding bottom surface (218), a top plane (229), and a protruding height (220). The protruding structural solid portion (217a) has a protruding structural solid portion top surface (219), a protruding structural solid portion side surface (221), and a protruding structural solid portion bottom surface (218a). The protruding structural solid portion top surface (219) is a point or a group of points of the protruding structural solid portion (217a), and the distance of this point or group of points from the microcell opening (205) is shorter than all other points of the protruding structural solid portion (217a). The top plane (229) is a plane parallel to the plane of the microcell opening (205) and including the protruding structural solid portion top surface (219). The side surface (221) of the protruding structural solid portion is the surface of the protruding structural solid portion (217a) in contact with the electrophoretic medium (209) (excluding the top end (219) of the protruding structural solid portion), the bottom surface (218a) of the protruding structural solid portion is the surface of the protruding structural solid portion (217a) in contact with the inner surface (211) of the bottom of the microcell, the bottom surface (218) of the protruding structure is the surface of the protruding structural solid portion (217a) and the one or more wells in contact with the bottom layer (210) of the microcell, the protrusion height (220) is the distance between the top plane (229) and the bottom surface (218) of the protruding structure, the protruding structure (217) has a three-dimensional shape, the three-dimensional shape of the protruding structure is a cylinder or a polygonal prism, the polygonal prism has a first bottom surface and a second bottom surface, the first bottom surface and the second bottom surface each have 3 to 20 sides; The one or more wells (217b) have a volume filled with the electrophoretic medium (209), and each of the one or more wells (217b) has a three-dimensional shape composed of one geometric shape or a combination of two or more geometric shapes. The three-dimensional shape of each of the one or more wells (217b) is defined by the space between (i) the top plane (229), (ii) the side surface (221) of the protruding structural solid portion, and (iii) the inner surface (211) of the bottom of the microcell. The one geometric shape and each of the two or more geometric shapes in the three-dimensional shape of each of the one or more wells are selected from the following: A group consisting of: a cone, a frustum of a cone, a cylinder, a polygonal pyramid, a frustum of a polygonal pyramid, and a polygonal prism, wherein the cone has a base and a apex, the frustum of a cone has a large base and a small base, the cylinder has a first base and a second base, the polygonal pyramid has a base and a apex, the base of the polygonal pyramid is a polygon with 3 to 20 sides, the frustum of a polygon has a large base and a small base, the large and small bases of the frustum of a polygon are polygons with 3 to 20 sides, and the polygonal prism has a first base and a second base, the first and second bases of the polygonal prism are polygons with 3 to 20 sides; The microcell wall (212) has an inner surface (213) and an upper surface (214). The inner surface (213) is the surface in contact between the microcell wall (212) of a microcell and the electrophoretic medium (209), and the upper surface (214) is the surface in contact between the microcell wall (212) of a microcell and the sealing layer (206). The variable light transmission device has a first outer surface (250) and a second outer surface (251). The first outer surface (250) is located on the side of the variable light transmission device closer to the first light-transmitting electrode layer (202), while the second outer surface (251) is located on the side of the variable light transmission device closer to the second light-transmitting electrode layer (207). A first electric field with a first waveform is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), causing the charged pigment particles to move toward the one or more wells (217b), thereby causing the variable light transmission device to switch to an optical state. A second electric field is applied with a second waveform between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207) to cause the charged pigment particles to move toward the first light-transmitting electrode layer (202), wherein the closed optical state has a lower percentage of transparency than the open optical state.

[0120] Clause 2: A variable light transmission device (300), comprising: First transparent electrode layer (202); A second light-transmitting electrode layer (207); and A microcell layer (203) is disposed between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207). The microcell layer (203) includes a plurality of microcells (204) and a sealing layer (206). Each microcell in the plurality of microcells (204) contains an electrophoretic medium (209), which contains charged pigment particles and a nonpolar liquid. Each microcell in the plurality of microcells (204) has a microcell opening (205). The sealing layer (206) spans the microcell openings (205) of the plurality of microcells (204). Each microcell's sealing layer (206) has an upper surface and a lower surface, the lower surface being in contact with the electrophoretic medium (209), and the upper surface being in contact with (i) the first light-transmitting electrode layer (202) or (ii) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the upper surface of the sealing layer (206); Each of the plurality of microcells (204) includes a microcell base layer (210), a channel (215), a protrusion structure (217) and a microcell wall (212), wherein the microcell base layer (210) has a microcell bottom inner surface (211); The microcell wall (212) has an inner surface (213) and an upper surface (214). The inner surface (213) is the surface in contact with the electrophoretic medium (209), and the upper surface (214) is the surface in contact with the sealing layer (206). The protruding structure (217) consists of a protruding structural solid portion (217a) and one or more wells (217b). The protruding structure (217) has a protruding bottom surface (218), a top plane (229), and a protrusion height (220). The protruding structural solid portion (217a) has a protruding structural solid portion top surface (219), a protruding structural solid portion side surface (221), and a protruding structural solid portion bottom surface (218a). The protruding structural solid portion top surface (219) is a point or a group of points of the protruding structural solid portion (217a). The distance of this point or group of points from the microcell opening (205) is shorter than that of all other points of the protruding structural solid portion (217a). The top plane ( 229) is a plane parallel to the plane of the microcell opening (205) and including the top end (219) of the protruding structural entity portion; the side surface (221) of the protruding structural entity portion is the surface of the protruding structural entity portion (217a) in contact with the electrophoretic medium (209), excluding the top end (219) of the protruding structural entity portion; the bottom surface (218a) of the protruding structural entity portion is the surface of the protruding structural entity portion (217a) in contact with the inner surface (211) of the bottom of the microcell; the bottom surface (218) of the protrusion is the surface of the protruding structural entity portion and the one or more wells in contact with the bottom layer (210) of the microcell; the protrusion height (220) is the distance between the top end plane (229) and the bottom surface (218) of the protrusion. The protruding structure has a three-dimensional shape, which is composed of one geometric shape or a combination of two or more geometric shapes. Each of the one geometric shape and the two or more geometric shapes in the three-dimensional shape of the protruding structure is selected from the group consisting of: a cylinder, a polygonal prism, a frustum of a cone, and a frustum of a polygon. The cylinder has a first base and a second base. The polygonal prism has a first base and a second base. The first base and the second base of the polygonal prism are polygons with 3 to 20 sides. The frustum of a cone has a large base and a small base. The large base and the small base of the frustum of a polygon are polygons with 3 to 20 sides. The side surface (221) of the protruding structural entity is composed of an inner side surface (221b) and an outer side surface (221a) of the protruding structural entity. The inner side surface (221b) is the part of the side surface (221) of the protruding structural entity that contacts the one or more wells (217b), and the outer side surface (221a) is the part of the side surface (221) of the protruding structural entity that does not contact the one or more wells (217b). The inner surface (211) of the microcell bottom is composed of an unexposed inner surface (211a), a first exposed inner surface (211b), and a second exposed inner surface (211c). The unexposed inner surface (211a) is in contact with the bottom surface (218a) of the protruding structure solid portion, but not with the electrophoretic medium (209). The first exposed inner surface (211b) and the second exposed inner surface (211c) are in contact with the electrophoretic medium (209). The first exposed inner surface (211c) is in contact with the channel (215), and the second exposed inner surface (211b) is in contact with the one or more wells (217b). The channel (215) has a channel height (216h), an inner bottom perimeter (225), and an outer bottom perimeter (226). The channel (215) has a volume filled with the electrophoretic medium (209). The channel is a three-dimensional shape defined by the outer surface (221a) of the protruding structural solid portion, the inner surface (211b) of the first exposed microcell bottom, the inner surface (213) of the microcell wall, and a plane parallel to the inner surface (211b) of the first exposed microcell bottom. The distance between the plane and the inner surface (211b) of the first exposed microcell bottom is equal to the channel height (216h), which is 50% of the protrusion height (220). The inner bottom perimeter (225) is the intersection of the microcell wall (212) and the inner surface (211b) of the first exposed microcell bottom. The outer bottom perimeter (226) is the intersection of the outer surface (221a) of the protruding structure solid portion and the inner surface (211b) of the first exposed microcell bottom. Each of the one or more wells (217b) has a volume filled with the electrophoretic medium (209), and each of the one or more wells (217b) has a three-dimensional shape composed of one geometric shape or a combination of two or more geometric shapes. The three-dimensional shape of each of the one or more wells (217b) is defined by the space between (i) the top plane (229), (ii) the inner surface (221b) of the protruding structural solid portion, and (iii) the inner surface (211c) of the bottom of the second exposed microcell. The shape is selected from the group consisting of: a cone, a frustum, a cylinder, a polygonal pyramid, a frustum, and a prism, wherein the cone has a base and a apex, the frustum has a large base and a small base, the cylinder has a first base and a second base, the polygonal pyramid has a base and a apex, the base of the polygonal pyramid is a polygon with 3 to 20 sides, the frustum has a large base and a small base, the large and small bases of the frustum are polygons with 3 to 20 sides, and the prism has a first base and a second base, the first and second bases of the prism are polygons with 3 to 20 sides. The variable light transmission device has a first outer surface (250) and a second outer surface (251). The first outer surface (250) is located on the side of the variable light transmission device closer to the first light-transmitting electrode layer (202), while the second outer surface (251) is located on the side of the variable light transmission device closer to the second light-transmitting electrode layer (207). A first electric field with a first waveform is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), causing the charged pigment particles to move toward the one or more wells (217b) and the channel, thereby causing the variable light transmission device to switch to an on optical state; A second electric field is applied with a second waveform between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207) to cause the charged pigment particles to move toward the first light-transmitting electrode layer (202), wherein the closed optical state has a lower percentage of transparency than the open optical state.

[0121] Clause 3: The variable light transmission device (200, 300) as described in Clause 1 or 2, wherein the three-dimensional shape of each of the one or more wells is selected from the group consisting of: (a) a cone or a polygonal pyramid, the base of which contacts the apex plane (229), and the apex of which contacts the inner surface (211) of the cell base; (b) a cylinder, a frustum, a frustum of a polygon, or a polygonal prism, the first base of which, the large base of which, the large base of which, or the first base of which contacts the apex plane (229), and the second base of which, the small base of which, the large base of which, or the small base of which, contacts the apex plane (229), and the second base of which, the small base of which, the large base of which, or the small base of which, contacts the apex plane (211); (c) A cylinder or a first frustum is located on a cone or a second frustum, the first bottom surface of the cylinder is in contact with the top plane (229), the second bottom surface of the cylinder is in contact with the bottom surface of the cone or the large bottom surface of the frustum, and the top surface of the cone or the small bottom surface of the frustum is in contact with the inner surface of the bottom of the microcell; (d) A polygonal prism or a first frustum is located on a polygonal pyramid or a second frustum, the first bottom surface of the polygonal prism or the large bottom surface of the first frustum is in contact with the top plane (229), and the second bottom surface of the polygonal prism or the small bottom surface of the first frustum is in contact with the bottom plane (229). The first and second bottom surfaces of the prism, the large and small bottom surfaces of the first truncated polygon, the bottom surface of the pyramid, and the large and small bottom surfaces of the second truncated polygon have the same number of sides; (e) A first truncated polygon is located on a pyramid, a second truncated polygon, or a prism, the large bottom surface of the first truncated polygon contacts the top surface (229), the small bottom surface of the first truncated polygon contacts the bottom surface of the pyramid, the large bottom surface of the second truncated polygon, or the first bottom surface of the prism, and the top surface of the pyramid or the second truncated polygon has the same number of sides. The small base of the frustum or the second base of the prism is in contact with the inner surface of the bottom of the microcell, wherein the large and small bases of the first frustum, the large and small bases of the second frustum, the bottom of the pyramid, and the first and second bases of the prism have the same number of sides; (f) A first frustum is located on a cone, a second frustum, or a cylinder, the large base of the first frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the bottom surface of the cone, the large base of the second frustum, or the first bottom surface of the cylinder, and the top of the cone, the small base of the second frustum, or the second bottom surface of the cylinder is in contact with the inner surface of the bottom of the microcell;(g) A first cylinder is located on a first truncated cone, the first truncated cone being located on a cone, a second truncated cone, or a second cylinder, the first bottom surface of the first cylinder contacting the top plane (229), the second bottom surface of the first cylinder contacting the large bottom surface of the first truncated cone, the small bottom surface of the first truncated cone contacting the bottom surface of the cone, the large bottom surface of the second truncated cone, or the first bottom surface of the second cylinder, and the top surface of the cone, the small bottom surface of the second truncated cone, or the second bottom surface of the second cylinder contacting the inner surface of the cell bottom; (h) A first truncated cone is located on a cylinder or a second truncated cone. Above, the cylinder or the second frustum is located on a cone or a third frustum, the large base of the first frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the first bottom surface of the cylinder or the large base of the second frustum, the second bottom surface of the cylinder or the small base of the second frustum is in contact with the bottom surface of the cone or the large base of the third frustum, and the top of the cone or the small base of the third frustum is in contact with the inner surface of the bottom of the microcell; (i) a first frustum is located on a second frustum, the second frustum is located on a cone or a third frustum or a cylinder, the first cylinder The large base of the frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the large base of the second frustum, the small base of the second frustum is in contact with the bottom surface of the cone or the large base of the third frustum or the first bottom surface of the cylinder, and the top of the cone or the small base of the third frustum or the second bottom surface of the cylinder is in contact with the inner surface of the bottom of the microcell; (j) a first polygonal frustum is located on a pyramidal prism or a second polygonal frustum, the pyramidal prism or the second polygonal frustum is located on a polygonal pyramid or a third polygonal frustum, the large base of the first polygonal frustum is in contact with the top plane (229). 9) Contact: The small base of the first truncated pyramid is in contact with the first base of the pyramidal prism or the large base of the second truncated pyramid; the second base of the pyramidal prism or the small base of the second truncated pyramid is in contact with the base of the pyramid or the large base of the third truncated pyramid; and the apex of the pyramid or the small base of the third truncated pyramid is in contact with the inner surface of the bottom of the microcell. The large and small bases of the first truncated pyramid, the first and second bases of the pyramidal prism, the large and small bases of the second truncated pyramid, the base of the pyramid, and the large and small bases of the third truncated pyramid have the same number of sides.And (k) a first polyhedral frustum is located on a second polyhedral frustum, which is located on a polyhedral pyramid, a third polyhedral frustum, or a polyhedral prism. The large base of the first polyhedral frustum is in contact with the apex plane (229), the small base of the first polyhedral frustum is in contact with the large base of the second polyhedral frustum, the small base of the second polyhedral frustum is in contact with the base of the polyhedral pyramid, the large base of the third polyhedral frustum, or the first base of the polyhedral prism, and the apex of the polyhedral pyramid, the small base of the third polyhedral frustum, or the second base of the polyhedral prism is in contact with the inner surface of the cell bottom. The large and small bases of the first, second, and third polyhedral frustums, the first and second bases of the polyhedral prism, and the base of the polyhedral pyramid have the same number of sides.

[0122] Clause 4: For any of Clauses 1 to 3, the variable light transmission device (200, 300) wherein the three-dimensional shape of the protruding structure (217) is selected from the group consisting of: (a) a cylinder, the first base of which is the protruding base (218), and the second base of which is in contact with the top plane (229); (b) a polygonal prism, the first base of which is the protruding base (218), and the second base of which is in contact with the top plane (229); (c) A frustum of a cone, the large base of which is the convex base (218), and the small base of which is in contact with the top plane (229); (d) A frustum of a polygon, the large base of which is the convex base (218), and the small base of which is in contact with the top plane (229), the large base of which is in contact with the top plane (229 ... and the small base of which is in contact with the top plane (229), the large base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (229), and the small base of which is in contact with the top plane (2 (e) A first frustum of a cone is located on a cylinder or a second frustum of a cone, the first base of the cylinder or the large base of the second frustum of a cone being the raised base (218), the second base of the cylinder or the small base of the second frustum of a cone contacting the large base of the first frustum of a cone, and the small base of the first frustum of a cone contacting the apex plane (229); and (f) A first frustum of a polygon is located on a polygonal cylinder or a second polygonal cone. On the platform, the first bottom surface of the polygonal prism or the large bottom surface of the second polygonal frustum is the raised bottom surface (218), the second bottom surface of the polygonal prism or the small bottom surface of the second polygonal frustum is in contact with the large bottom surface of the first polygonal frustum, and the small bottom surface of the first polygonal frustum is in contact with the top plane (229), wherein the large bottom surface and small bottom surface of the first and second polygonal frustums and the first bottom surface and second bottom surface of the polygonal prism each have the same number of sides (3 to 20 sides).

[0123] Clause 5: The variable light transmission device as in Clause 1, wherein the opening (205) of each of the plurality of microcells (204) of the microcell layer (203) has a shape, the shape of the opening (205) being selected from the group consisting of: a circle, an ellipse, a square, a rectangle and a polygon having 5 to 12 sides.

[0124] Clause 6: A variable light transmission device as described in any of Clauses 1 to 5, wherein each of the plurality of microcells (204) has a length of 400 micrometers to 800 micrometers and a height of 20 micrometers to 100 micrometers.

[0125] Clause 7: A variable light transmission device as described in any of Clauses 2 to 6, wherein the channel (215) has a width of 10 micrometers to 30 micrometers.

[0126] Clause 8: A variable light transmission device as described in any of Clauses 2 to 7, wherein the inner surface of the microcell wall (213) forms an angle (φ) of 90 to 120 degrees with the inner surface of the first exposed microcell bottom (211b).

[0127] Clause 9: A variable light transmission device as described in any of Clauses 1 to 8, wherein the variable light transmission device comprises: (i) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the sealing layer (206); (ii) a second adhesive layer disposed between the microcell layer (203) and the second light-transmitting electrode layer (207); or (iii) the adhesive layer and the second adhesive layer.

[0128] Clause 10: A variable light transmission device as described in any of Clauses 1 to 9, wherein the variable light transmission device includes a light blocking layer (230) disposed between the upper surface (214) of the microcell wall and the sealing layer (206), the light blocking layer (230) containing light-absorbing pigment.

[0129] Clause 11: The variable light transmission device as described in Clause 10, wherein the light-absorbing pigment of the light-blocking layer (230) is black.

[0130] Clause 12: A variable light transmission device as described in any of Clauses 1 to 11, wherein the charged pigment particles (223) of the electrophoretic medium (209) absorb light.

[0131] Clause 13: A variable light transmission device as described in any of Clauses 1 to 12, wherein the second electric field causes the charged pigment particles (223) to move toward the first light-transmitting electrode layer (202) at a velocity having a lateral component.

[0132] Clause 14: A variable light transmission device as described in any of Clauses 1 to 13, wherein the second waveform includes at least one positive voltage and at least one negative voltage, and the second waveform has a net positive pulse or a net negative pulse.

[0133] Clause 15: The variable light transmission device as described in Clause 14, wherein the second waveform includes an AC waveform having a duty cycle of 5% to 45%, or wherein the second waveform includes a DC bias waveform formed by superimposing a DC voltage component with an AC waveform.

[0134] Clause 16: A variable light transmission device as described in any of Clauses 1 to 15, wherein the variable light transmission device includes a microcell having a protruding structure comprising 10 to 39 wells.

[0135] Clause 17: A variable light transmission device as described in any of Clauses 2 to 15, wherein the variable light transmission device includes a microcell having a protrusion structure comprising 1 to 3 wells.

[0136] Clause 18: A variable light transmission device as described in any of Clauses 1 to 15, wherein the variable light transmission device includes a microcell having a protrusion structure comprising 1 to 5 wells.

[0137] Clause 19: A variable light transmission device as described in any of Clauses 1 to 15, wherein the variable light transmission device includes a microcell having a protrusion structure comprising 1 to 10 wells.

[0138] Clause 20: A variable light transmission device as described in any of Clauses 1 to 15, wherein the variable light transmission device includes a microcell having a protrusion structure comprising 1 to 15 wells. Component symbols in the attached diagram

[0139] 200, 300, 350: Variable light transmission device according to the first embodiment; 500, 550, 560, 580, 590, 600, 650: Variable light transmission device according to the second embodiment; 201: First light-transmitting substrate; 202: First light-transmitting electrode layer; 203: Microcell layer; 204: Proximity of microcells; 205: Microcell opening; 206: Sealing layer; 207: Second light-transmitting electrode layer; 208: Second light-transmitting substrate; 209: Electrophoretic medium; 210: Microcell bottom layer; 211: Inner surface of microcell bottom; 211a: Unexposed inner surface of microcell bottom; 211b: First exposed inner surface of microcell bottom; 211c: 212: Microcell wall; 213: Microcell wall inner surface; 214: Microcell wall upper surface; 215: Channel; 216h: Channel height; 216w: Channel bottom width; 217: Protrusion structure; 217a: Protrusion structure solid part; 217b: Well; 218: Protrusion bottom surface; 219: Protrusion structure solid part top; 220: Protrusion height; 221: Protrusion side surface; 221a: Protrusion outer surface; 221b: Protrusion inner surface; 223: Charged pigment particle; 224: Channel inner bottom perimeter; 225: Channel outer bottom perimeter; 602: Electric field.

[0140] 200: Variable light transmission device 201: First transparent substrate 202: First transparent electrode layer 203: Microcellular layer 204: microcell 205: Microcell opening 206: Sealing layer 207: Second transparent electrode layer 208: Second transparent substrate 209: Electrophoretic medium 210: Microcellular basal layer 211: Inner surface of the cell base 211a: Unexposed inner surface of the microcellular base 211b: First exposed inner surface of the microcell base 211c: Second exposed inner surface of the microcell base 212: Microcell wall 213: Inner surface of microcell wall 214: Upper surface of the cell wall 215: Channel 216h: Channel height 216w: Width of the bottom surface of the channel 217: Protruding structure 217a: Protruding structural solid part 217b: Well 218: Raised bottom surface 219: Top of the protruding structural solid part 220: Protrusion height 221: Side surface of the solid part of the protruding structure 221a: Outer surface of the solid part of the protruding structure 221b: Inner surface of the solid part of the protruding structure 223: Charged pigment particles 225: Inner bottom perimeter 226: Perimeter of the outer bottom surface 229: Top plane 230: Light blocking layer 250: First outer surface 251: Second outer surface 300: Variable light transmission device 350: Variable light transmission device 500: Variable light transmission device 550: Variable light transmission device 560: Variable light transmission device 580: Variable light transmission device 590: Variable light transmission device 600: Variable light transmission device 602: Electric Field 650: Variable light transmission device φ: Angle θ1: First slope θ2: Second slope

Claims

1. A variable light transmission device (200), comprising: A first light-transmitting electrode layer (202); A second light-transmitting electrode layer (207); And a microcell layer (203) disposed between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), the microcell layer (203) comprising a plurality of microcells (204) and a sealing layer (206), each of the plurality of microcells (204) comprising an electrophoretic medium (209) comprising charged pigment particles and a nonpolar liquid, each of the plurality of microcells (204) having a microcell opening (205), the sealing layer (206) spanning the microcell openings (205) of the plurality of microcells (204); Each microcell's sealing layer (206) has an upper surface and a lower surface, the lower surface being in contact with the electrophoretic medium (209), and the upper surface being in contact with (i) the first light-transmitting electrode layer (202) or (ii) an adhesive layer, the adhesive layer being disposed between the first light-transmitting electrode layer (202) and the upper surface of the sealing layer (206); each of the plurality of microcells (204) includes a microcell bottom layer (210), a protrusion structure (217) and a microcell wall (212), the microcell bottom layer (210) having a microcell bottom inner surface (211); The protruding structure (217) consists of a protruding structural solid portion (217a) and one or more wells (217b). The protruding structure (217) has a protruding bottom surface (218), a top plane (229), and a protruding height (220). The protruding structural solid portion (217a) has a protruding structural solid portion top surface (219), a protruding structural solid portion side surface (221), and a protruding structural solid portion bottom surface (218a). The protruding structural solid portion top surface (219) is a point or a group of points of the protruding structural solid portion (217a), and the distance of this point or group of points from the microcell opening (205) is shorter than all other points of the protruding structural solid portion (217a). The top plane (229) is a plane parallel to the plane of the microcell opening (205) and includes the top surface (219) of the protruding structural solid portion. The side surface (221) of the solid part of the protruding structure is the surface in contact with the electrophoretic medium (209) of the solid part of the protruding structure (217a) (excluding the top end (219) of the solid part of the protruding structure), the bottom surface (218a) of the solid part of the protruding structure is the surface in contact with the inner surface (211) of the bottom of the microcell, the bottom surface (218) of the protruding structure is the surface in contact with the solid part of the protruding structure and the one or more wells and the bottom layer (210) of the microcell, the protrusion height (220) is the distance between the top plane (229) and the bottom surface (218) of the protruding structure, the protruding structure (217) has a three-dimensional shape, the three-dimensional shape of the protruding structure is a cylinder or a polygonal prism, the polygonal prism has a first bottom surface and a second bottom surface, the first bottom surface and the second bottom surface each have 3 to 20 sides;The one or more wells (217b) have a volume filled with the electrophoretic medium (209), and each of the one or more wells (217b) has a three-dimensional shape composed of one geometric shape or a combination of two or more geometric shapes. The three-dimensional shape of each of the one or more wells (217b) is defined by the space between (i) the top plane (229), (ii) the side surface (221) of the protruding structural solid portion, and (iii) the inner surface (211) of the bottom of the microcell. The one geometric shape and each of the two or more geometric shapes in the three-dimensional shape of each of the one or more wells are selected from the following: A group consisting of: a cone, a frustum of a cone, a cylinder, a polygonal pyramid, a frustum of a polygonal pyramid, and a polygonal prism, wherein the cone has a base and a apex, the frustum of a cone has a large base and a small base, the cylinder has a first base and a second base, the polygonal pyramid has a base and a apex, the base of the polygonal pyramid is a polygon with 3 to 20 sides, the frustum of a polygon has a large base and a small base, the large and small bases of the frustum of a polygon are polygons with 3 to 20 sides, and the polygonal prism has a first base and a second base, the first and second bases of the polygonal prism are polygons with 3 to 20 sides; The microcell wall (212) has an inner surface (213) and an upper surface (214). The inner surface (213) is the surface in contact between the microcell wall (212) of a microcell and the electrophoretic medium (209). The upper surface (214) is the surface in contact between the microcell wall (212) of a microcell and the sealing layer (206). The variable light transmission device has a first outer surface (250) and a second outer surface (251). The first outer surface (250) is located on the side of the variable light transmission device closer to the first light-transmitting electrode layer (202), and the second outer surface (251) is located on the side of the variable light transmission device closer to the second light-transmitting electrode layer (207). In this process, a first electric field with a first waveform is applied between the first transparent electrode layer (202) and the second transparent electrode layer (207), causing the charged pigment particles to move toward one or more wells (217b), thereby causing the variable light transmission device to switch to an open optical state; In this process, a second electric field with a second waveform is applied between the first transparent electrode layer (202) and the second transparent electrode layer (207), causing the charged pigment particles to move toward the first transparent electrode layer (202), wherein the closed optical state has a lower percentage of transparency than the open optical state.

2. The variable light transmission device (200) as claimed in claim 1, wherein, The three-dimensional shape of each of the one or more wells is selected from the group consisting of: (a) a cone or a polygonal pyramid, the base of which contacts the apex plane (229), and the apex of which contacts the inner surface (211) of the cell bottom; (b) a cylinder, a frustum, a frustum of a polygon, or a polygonal prism, the first base of which, the major base of which, the major base of which, or the first base of which contacts the apex plane (229), and the second base of which, the minor base of which, or the minor base of which, or the second base of which contacts the inner surface of the cell bottom. (c) A cylinder or a first frustum of a cone or a second frustum, wherein the first base of the cylinder contacts the top plane (229), the second base of the cylinder contacts the base of the cone or the large base of the frustum, and the top of the cone or the small base of the frustum contacts the inner surface of the cell bottom; (d) A polygonal prism or a first frustum of a polygonal pyramid, wherein the first base of the polygonal prism or the large base of the first frustum of a polygonal pyramid contacts the top plane (229), and the second base of the polygonal prism or the small base of the first frustum of a polygonal pyramid contacts the base of the polygonal pyramid or the large base of the second frustum of a polygonal pyramid. The top of the polygonal pyramid or the small base of the second polygonal frustum is in contact with the inner surface of the cell bottom, wherein the first and second bases of the polygonal prism, the large and small bases of the first polygonal frustum, the base of the polygonal pyramid, and the large and small bases of the second polygonal frustum have the same number of sides; (e) A first polygonal frustum is located on a polygonal pyramid, a second polygonal frustum, or a polygonal prism, the large base of the first polygonal frustum is in contact with the top plane (229), the small base of the first polygonal frustum is in contact with the base of the polygonal pyramid, the large base of the second polygonal frustum, or the first base of the polygonal prism, and the top of the polygonal pyramid or the small base of the second polygonal frustum. Or the second bottom surface of the polygonal prism is in contact with the inner surface of the bottom of the microcell, wherein the large and small bottom surfaces of the first polygonal frustum, the large and small bottom surfaces of the second polygonal frustum, the bottom surface of the polygonal pyramid, and the first and second bottom surfaces of the polygonal prism have the same number of sides; (f) a first frustum is located on a cone or a second frustum or a cylinder, the large bottom surface of the first frustum is in contact with the top plane (229), the small bottom surface of the first frustum is in contact with the bottom surface of the cone or the large bottom surface of the second frustum or the first bottom surface of the cylinder, and the top surface of the cone or the small bottom surface of the second frustum or the second bottom surface of the cylinder is in contact with the inner surface of the bottom of the microcell;(g) A first cylinder is located on a first truncated cone, the first truncated cone being located on a cone, a second truncated cone, or a second cylinder, the first bottom surface of the first cylinder contacting the top plane (229), the second bottom surface of the first cylinder contacting the large bottom surface of the first truncated cone, the small bottom surface of the first truncated cone contacting the bottom surface of the cone, the large bottom surface of the second truncated cone, or the first bottom surface of the second cylinder, and the top surface of the cone, the small bottom surface of the second truncated cone, or the second bottom surface of the second cylinder contacting the inner surface of the bottom of the microcell; (h) A first truncated cone is located on a cylinder or a second truncated cone. Above, the cylinder or the second frustum is located on a cone or a third frustum, the large base of the first frustum is in contact with the top plane (229), the small base of the first frustum is in contact with the first bottom surface of the cylinder or the large base of the second frustum, the second bottom surface of the cylinder or the small base of the second frustum is in contact with the bottom surface of the cone or the large base of the third frustum, and the top of the cone or the small base of the third frustum is in contact with the inner surface of the bottom of the microcell; (i) a first frustum is located on a second frustum, the second frustum is located on a cone or a third frustum or a cylinder, the first cylinder The large base of the frustum contacts the top plane (229), the small base of the first frustum contacts the large base of the second frustum, the small base of the second frustum contacts the bottom surface of the cone or the large base of the third frustum or the first bottom surface of the cylinder, and the top of the cone or the small base of the third frustum or the second bottom surface of the cylinder contacts the inner surface of the bottom of the microcell; (j) a first polygonal frustum is located on a pyramidal prism or a second polygonal frustum, the pyramidal prism or the second polygonal frustum is located on a polygonal pyramid or a third polygonal frustum, the large base of the first polygonal frustum contacts the top plane (229). The small base of the first truncated pyramid is in contact with the first base of the pyramidal prism or the large base of the second truncated pyramid; the second base of the pyramidal prism or the small base of the second truncated pyramid is in contact with the base of the pyramid or the large base of the third truncated pyramid; and the apex of the pyramid or the small base of the third truncated pyramid is in contact with the inner surface of the bottom of the microcell. The large and small bases of the first truncated pyramid, the first and second bases of the pyramidal prism, the large and small bases of the second truncated pyramid, the base of the pyramid, and the large and small bases of the third truncated pyramid have the same number of sides.And (k) a first polyhedral frustum is located on a second polyhedral frustum, which is located on a polyhedral pyramid, a third polyhedral frustum, or a polyhedral prism. The large base of the first polyhedral frustum is in contact with the apex plane (229), the small base of the first polyhedral frustum is in contact with the large base of the second polyhedral frustum, the small base of the second polyhedral frustum is in contact with the base of the polyhedral pyramid, the large base of the third polyhedral frustum, or the first base of the polyhedral prism, and the apex of the polyhedral pyramid, the small base of the third polyhedral frustum, or the second base of the polyhedral prism is in contact with the inner surface of the cell bottom. The large and small bases of the first, second, and third polyhedral frustums, the first and second bases of the polyhedral prism, and the base of the polyhedral pyramid have the same number of sides.

3. The variable light transmission device (200) as claimed in claim 1, wherein, The three-dimensional shape of the protrusion structure (217) is selected from the group consisting of: (a) a cylinder, the first base of which is the protrusion base (218), and the second base of which is in contact with the top plane (229); (b) a polygonal prism, the first base of which is the protrusion base (218), and the second base of which is in contact with the top plane (229), the first base and the second base... Each of the following surfaces has 3 to 20 sides: (c) a frustum of a cone, the major base of which is the convex base (218), and the minor base of which contacts the apex plane (229); (d) a frustum of a polygon, the major base of which is the convex base (218), and the minor base of which contacts the apex plane (229), wherein the major and minor bases of the frustum of a polygon each have the same number of sides (3 to 20 sides); (e) A first truncated cone is located on a cylinder or a second truncated cone, the first base of the cylinder or the large base of the second truncated cone being the raised base (218), the second base of the cylinder or the small base of the second truncated cone contacting the large base of the first truncated cone, and the small base of the first truncated cone contacting the top plane (229); and (f) A first truncated polygon is located on a polygonal prism or a second truncated polygon, the first base of the polygonal prism or the large base of the second truncated polygon is the raised base (218), the second base of the polygonal prism or the small base of the second truncated polygon contacting the large base of the first truncated polygon, and the small base of the first truncated polygon contacting the top plane (229), wherein the large and small bases of the first and second truncated polygons and the first and second bases of the polygonal prism each have the same number of sides (3 to 20 sides).

4. The variable light transmission device as claimed in claim 1, wherein, The microcell opening (205) of each of the plurality of microcells (204) in the microcell layer (203) has a shape selected from the group consisting of: a circle, an ellipse, a square, a rectangle and a polygon having 5 to 12 sides.

5. The variable light transmission device as claimed in claim 1, wherein, Each of the plurality of microcells (204) has a length of 400 to 800 micrometers and a height of 20 to 100 micrometers.

6. The variable light transmission device as claimed in claim 1, wherein, The variable light transmission device includes: (i) an adhesive layer disposed between the first light-transmitting electrode layer (202) and the sealing layer (206); (ii) a second adhesive layer disposed between the microcell layer (203) and the second light-transmitting electrode layer (207); or (iii) the adhesive layer and the second adhesive layer.

7. The variable light transmission device as claimed in claim 1, wherein, The variable light transmission device includes a light blocking layer (230) disposed between the upper surface (214) of the microcell wall and the sealing layer (206), the light blocking layer (230) containing light-absorbing pigment.

8. The variable light transmission device as claimed in claim 7, wherein, The light-absorbing pigment of the light-blocking layer (230) is black.

9. The variable light transmission device as claimed in claim 1, wherein, The charged pigment particles (223) of the electrophoretic medium (209) absorb light.

10. The variable light transmission device as claimed in claim 1, wherein, The second electric field causes the charged pigment particles (223) to move toward the first transparent electrode layer (202) at a velocity having a transverse component.

11. The variable light transmission device as claimed in claim 1, wherein, The second waveform includes at least one positive voltage and at least one negative voltage, and the second waveform has a net positive pulse or a net negative pulse.

12. The variable light transmission device as claimed in claim 11, wherein, The second waveform includes an AC waveform having a duty cycle of 5% to 45%, or the second waveform includes a DC bias waveform formed by superimposing a DC voltage component with an AC waveform.

13. A variable light transmission device as claimed in any of claims 1 to 12, wherein, The variable light transmission device includes a microcell having a protruding structure containing one to three wells.

14. A variable light transmission device as claimed in any of claims 1 to 12, wherein, The variable light transmission device includes a microcell having a protruding structure containing 1 to 5 wells.

15. A variable light transmission device as claimed in any of claims 1 to 12, wherein, The variable light transmission device includes a microcell having a protruding structure containing 1 to 10 wells.

16. A variable light transmission device as claimed in any of claims 1 to 12, wherein, Each microcell includes a protrusion structure containing 5 to 39 wells.

17. A variable light transmission device (300), comprising: A first light-transmitting electrode layer (202); A second light-transmitting electrode layer (207); And a microcell layer (203) disposed between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), the microcell layer (203) comprising a plurality of microcells (204) and a sealing layer (206), each of the plurality of microcells (204) comprising an electrophoretic medium (209) comprising charged pigment particles and a nonpolar liquid, each of the plurality of microcells (204) having a microcell opening (205), the sealing layer (206) spanning the microcell openings (205) of the plurality of microcells (204); Each microcell's sealing layer (206) has an upper surface and a lower surface, the lower surface being in contact with the electrophoretic medium (209), and the upper surface being in contact with (i) the first light-transmitting electrode layer (202) or (ii) an adhesive layer, the adhesive layer being disposed between the first light-transmitting electrode layer (202) and the upper surface of the sealing layer (206); each of the plurality of microcells (204) includes a microcell bottom layer (210), a channel (215), a protrusion structure (217) and a microcell wall (212), the microcell bottom layer (210) having a microcell bottom inner surface (211); The microcell wall (212) has an inner surface (213) and an upper surface (214). The inner surface (213) is the surface in contact with the electrophoretic medium (209), and the upper surface (214) is the surface in contact with the sealing layer (206).The protruding structure (217) consists of a protruding structural solid portion (217a) and one or more wells (217b). The protruding structure (217) has a protruding bottom surface (218), a top surface (229), and a protrusion height (220). The protruding structural solid portion (217a) has a protruding structural solid portion top surface (219), a protruding structural solid portion side surface (221), and a protruding structural solid portion bottom surface (218a). The protruding structural solid portion top surface (219) is a point or a group of points of the protruding structural solid portion (217a). The distance of this point or group of points from the microcell opening (205) is shorter than that of all other points of the protruding structural solid portion (217a). The top surface (217a) is... 29) is a plane parallel to the microcell opening (205) and including the top end (219) of the protruding structural entity portion. The side surface (221) of the protruding structural entity portion is the surface of the protruding structural entity portion (217a) in contact with the electrophoretic medium (209) (excluding the top end (219) of the protruding structural entity portion). The bottom surface (218a) of the protruding structural entity portion is the surface of the protruding structural entity portion (217a) in contact with the inner surface (211) of the bottom of the microcell. The bottom surface (218) of the protrusion is the surface of the protruding structural entity portion and the one or more wells in contact with the bottom layer (210) of the microcell. The protrusion height (220) is the distance between the top end plane (229) and the bottom surface (218) of the protrusion. The protruding structure has a three-dimensional shape, which is composed of one geometric shape or a combination of two or more geometric shapes. Each of the one geometric shape and the two or more geometric shapes in the three-dimensional shape of the protruding structure is selected from the group consisting of: a cylinder, a polygonal prism, a frustum of a cone, and a frustum of a polygon. The cylinder has a first base and a second base. The polygonal prism has a first base and a second base. The first base and the second base of the polygonal prism are polygons with 3 to 20 sides. The frustum of a cone has a large base and a small base. The frustum of a polygon has a large base and a small base. The large base and the small base of the frustum of a polygon are polygons with 3 to 20 sides. The side surface (221) of the protruding structural entity is composed of an inner side surface (221b) and an outer side surface (221a) of the protruding structural entity. The inner side surface (221b) is the part of the side surface (221) of the protruding structural entity that contacts the one or more wells (217b), and the outer side surface (221a) is the part of the side surface (221) of the protruding structural entity that does not contact the one or more wells (217b).The inner surface of the microcell bottom (211) is composed of an unexposed inner surface of the microcell bottom (211a), a first exposed inner surface of the microcell bottom (211b), and a second exposed inner surface of the microcell bottom (211c). The unexposed inner surface of the microcell bottom (211a) is in contact with the bottom surface (218a) of the protruding structure solid portion, but not with the electrophoretic medium (209). The first exposed inner surface of the microcell bottom (211b) and the second exposed inner surface of the microcell bottom (211c) are in contact with the electrophoretic medium (209). The first exposed inner surface of the microcell bottom (211b) is in contact with the channel (215), and the second exposed inner surface of the microcell bottom (211c) is in contact with the one or more wells (217b). The channel (215) has a channel height (216h), an inner bottom perimeter (225), and an outer bottom perimeter (226). The channel (215) has a volume filled with the electrophoretic medium (209). The channel is a three-dimensional shape defined by the outer surface (221a) of the protruding structural solid portion, the inner surface (211b) of the first exposed microcell bottom, the inner surface (213) of the microcell wall, and a plane parallel to the inner surface (211b) of the first exposed microcell bottom. The distance between the plane and the inner surface (211b) of the first exposed microcell bottom is equal to the channel height (216h), which is 50% of the protrusion height (220). The inner bottom perimeter (225) is the intersection of the microcell wall (212) and the inner surface (211b) of the first exposed microcell bottom. The outer bottom perimeter (226) is the intersection of the outer surface (221a) of the protrusion structure solid part and the inner surface (211b) of the first exposed microcell bottom.Each of the one or more wells (217b) has a volume filled with the electrophoretic medium (209), and each of the one or more wells (217b) has a three-dimensional shape composed of one geometric shape or a combination of two or more geometric shapes. The three-dimensional shape of each of the one or more wells (217b) is defined by the space between (i) the top plane (229), (ii) the inner surface (221b) of the protruding structural solid portion, and (iii) the inner surface (211c) of the bottom of the second exposed microcell. The shape is selected from the group consisting of: a cone, a frustum, a cylinder, a polygonal pyramid, a frustum and a prism, the cone having a base and a apex, the frustum having a large base and a small base, the cylinder having a first base and a second base, the polygon having a base and a apex, the base of the polygon being a polygon with 3 to 20 sides, the frustum having a large base and a small base, the large and small bases of the frustum being polygons with 3 to 20 sides, and the prism having a first base and a second base, the first and second bases of the prism being polygons with 3 to 20 sides. The variable light transmission device has a first outer surface (250) and a second outer surface (251). The first outer surface (250) is located on the side of the variable light transmission device closer to the first light-transmitting electrode layer (202), and the second outer surface (251) is located on the side of the variable light transmission device closer to the second light-transmitting electrode layer (207). A first electric field with a first waveform is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), causing charged pigment particles to move toward the one or more wells (217b) and the channel, thereby causing the variable light transmission device to switch to an open optical state. A second electric field with a second waveform is applied between the first light-transmitting electrode layer (202) and the second light-transmitting electrode layer (207), causing charged pigment particles to move toward the first light-transmitting electrode layer (202). The closed optical state has a lower percentage of transparency than the open optical state.

18. The variable light transmission device as claimed in claim 17, wherein, The channel (215) has a width of 10 micrometers to 30 micrometers.

19. The variable light transmission device as claimed in claim 17, wherein, The inner surface of the microcell wall (213) forms an angle (φ) of 90 to 120 degrees with the inner surface of the first exposed microcell base (211b).

20. A variable light transmission device as claimed in any of claims 17 to 19, wherein, The variable light transmission device includes a microcell having a protruding structure containing 1 to 10 wells.

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