Color electro-optic displays, and processes for the production thereof

Abstract

A color filter array is provided in an electro-optic display by ink jet printing a plurality of colored areas (22R, 22G, 22B) on one surface of a layer of electro-optic material (12), an adhesive layer or a protective layer. Alternatively, the ink jet printing may be effected on the same layers in various sub-assemblies used to produce electro-optic displays.

Description

REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of Application Ser. No. 60 / 825,933, filed Sep. 18, 2006. [0002] This application is also a continuation-in-part of copending application Ser. No. 11 / 550,114, filed Oct. 17, 2006 (Publication No. 2007 / 0109219), which itself claims benefit of Application Ser. No. 60 / 596,743, filed Oct. 18, 2005, and of Application Ser. No. 60 / 596,799, filed Oct. 21, 2005. [0003] This application is also related to: [0004] (a) application Ser. No. 10 / 249,957, filed May 22, 2003 (now U.S. Pat. No. 6,982,178), which claims benefit of Application Ser. No. 60 / 319,300, filed Jun. 10, 2002, and Application Ser. No. 60 / 320,186, filed May 12, 2003; [0005] (b) application Ser. No. 10 / 907,065, filed Mar. 18, 2005 (now U.S. Pat. No. 7,236,292), which is a divisional of the aforementioned application Ser. No. 10 / 249,957; [0006] (c) copending application Ser. No. 11 / 747,546, filed May 11, 2007, which is a continuation of the aforementioned app...

AI Technical Summary

Benefits of technology

[0059] This aspect of the present invention may hereinafter for convenience be called the “protective layer printing” or “PLP” aspect of the invention. Typically, this process will be used to print a full color filter array having two, three or four colors, although more colors can be used if desired. Thus, in a typical PLP process, a plurality of first colored areas and a plurality of second colored areas are printed on the surface of the layer of electro-

Problems solved by technology

Nevertheless, problems with the long-term image quality of these displays have prevented their widespread usage.

For example, particles that make up electrophoretic displays tend to settle, resulting in inadequate service-life for these displays.

Such gas-based electrophoretic media appear to be susceptible to the same types of problems due to particle settling as liquid-based electrophoretic media, when the media are used in an orientation which permits such settling, for example in a sign where the medium is disposed in a vertical plane.

Indeed, particle settling appears to be a more serious problem in gas-based electrophoretic media than in liquid-based ones, since the lower viscosity of gaseous suspending fluids as compared with liquid ones allows more rapid settling of the electrophoretic particles.

However, the methods used for assembling LCD's cannot be used with encapsulated electrophoretic displays.

This LCD assembly process cannot readily be transferred to solid electro-optic displays.

As discussed in the aforementioned U.S. Pat. No. 6,312,304, the manufacture of solid electro-optic displays also presents problems in that the optical components (the electro-optic medium) and the electronic components (in the backplane) have differing performance criteria.

Therefore, a process for manufacturing an optical component may not be ideal for manufacturing an electronic component, and vice versa.

The processing temperature can be in the range from about 300° C. to about 600° C. Subjecting many optical components to such high temperatures, however, can be harmful to the optical components by degrading the electro-optic medium chemically or by causing mechanical damage.

Electro-optic displays are often costly; for example, the cost of the color LCD found in a portable computer is typically a substantial fraction of the entire cost of the computer.

However, such equipment is costly and the areas of electro-optic media presently sold may be insufficient to justify dedicated equipment, so that it may typically be necessary to transport the coated medium from a commercial coating plant to the plant used for final assembly of electro-optic displays without damage to the relatively fragile layer of electro-optic medium.

Choosing the optimum method for providing a color filter array in an electro-optic display is more complex than it might at first appear, and involves a number of often-conflicting desiderata.

However, it is also necessary to consider the ease of incorporation of the color filter array into the selected position within the display; for example, it is relatively easy to attach a pre-formed color filter array on to the viewing surface of the display, but it may be substantially more difficult to place a color filter array between two interior layers of the display.

In this regard, it should be noted that thin front plane laminates (including inverted front plane laminates) and double release films tend to change size slightly during laminations, and even a small change in size can have severe effects on the electro-optic performance of the resulting display.

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