Protective electrodes for electrophoretic displays

Details Protective electrodes for electrophoretic displays Protective electrodes for electrophoretic displays

1999-12-20

2004-04-20

Sugarman, Scott J. (Department: 2873)

Optical: systems and elements

Optical modulator

Light wave temporal modulation

C345S109000

Reexamination Certificate

active

06724519

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to electronic displays and, in particular, to electrodes that protect displays from deterioration, their mode of use and their methods of fabrication.
BACKGROUND OF THE INVENTION
Electrophoretic displays have been the subject of intense research and development for a number of years. Electrophoretic displays have attributes of good brightness and contrast, wide viewing angles, state bistability, and low power consumption when compared with liquid crystal displays. Nevertheless, problems with the long-term image quality of these displays have prevented their widespread usage. For example, particles that make up such displays tend to cluster and settle, resulting in inadequate service-life for these displays.
An encapsulated, electrophoretic display typically does not suffer from the clustering and settling failure mode of traditional electrophoretic devices and provides further advantages, such as the ability to print or coat the display on a wide variety of flexible and rigid substrates.
Traditionally, electronic displays such as liquid crystal displays have been made by sandwiching an optoelectrically active material between two pieces of glass. In many cases each piece of glass has an etched, clear electrode structure formed using indium tin oxide (“ITO”). A first electrode structure controls all the segments of the display that may be addressed, that is, changed from one visual state to another. A second electrode, sometimes called a counter electrode, addresses all display segments as one large electrode, and is generally designed not to overlap any of the rear electrode wire connections that are not desired in the final image. Alternatively, the second electrode is also patterned to control specific segments of the displays. In these displays, unaddressed areas of the display have a defined appearance.
In electrophoretic displays, it has been commonly observed that the display fails after some time. One of the reasons why such a display may fail is that the materials is used to construct the display are damaged by repeated application of electrical addressing signals. Another reason why such displays fail is that the display elements or electrodes suffer mechanical or electrochemical damage.
SUMMARY OF THE INVENTION
In one aspect the invention provides novel apparatus and methods for providing protective electrodes for use in electrically addressable displays including electrophoretic displays. Additionally the invention discloses applications of these methods and materials in displays that can be flexible, that can be applied in large area, low cost, and high durability applications that operate under a variety of environments.
In one aspect, the present invention relates to a display that includes a display element capable of changing its appearance in response to an electric field, and a first electrode adjacent the display element, such that the first electrode provides a protective layer adapted to prevent mechanical or electrochemical damage to the display element
In one embodiment, the display includes an electrophoretic display element that has as components a capsule, a dispersing fluid having a first optical property disposed within the capsule, and at least one electrophoretically-mobile particle disposed within the capsule. The at least one electrophoretically-mobile particle has a second optical property different from the first optical property, and the at least one electrophoretically-mobile particle can change position within the capsule under the influence of an applied electric field. The appearance of the display element can change depending on where the at least one electrophoretically-mobile particle is situated within the capsule.
In other embodiments, the protective layer is flexible, and the protective layer is adapted to prevent mechanical removal of the electrophoretic element from the display. In yet another embodiment, the protective layer includes a plurality of conductors extending therethrough. In still another embodiment, the first electrode is transparent and the protective layer is disposed upon the transparent electrode, the protective layer being capable of protecting the transparent electrode from degradation under the application of an electrical potential. In a further embodiment, the first electrode is transparent and comprises one or more oxides selected from the group consisting of indium oxide, tin oxide and indium tin oxide.
In another embodiment, the protective layer comprises at least one chemical composition selected from the group consisting of the metals nickel, palladium, platinum, ruthenium, rhodium, silver, aluminum, gold, titanium, chromium and zinc, and the oxides silver oxide (AgO), aluminum oxide (Al
2
O
3
), gold (III) oxide (Au
2
O
3
), titanium (II) oxide (TiO), titanium (IV) oxide (TiO
2
), chromium (III) oxide (Cr
2
O
3
), chromium (VI) oxide (CrO
3
), zinc oxide (ZnO), nickel (II) oxide (NiO), palladium (II) oxide (PdO), platinum (IV) oxide (PtO
2
), ruthenium (IV) oxide (RuO
2
), and rhodium (III) oxide (Rh
2
O
3
). In a preferred embodiment, the protective layer comprises palladium. In still another embodiment, the protective layer has a thickness not greater than approximately 10 nm.
In another aspect, the invention relates to a display, that includes a display element, and a vapor-permeable electrode adjacent the display element. In one embodiment, the display includes an electrophoretic display element that has as components a capsule, a dispersing fluid having a first optical property disposed within the capsule, and at least one electrophoretically-mobile particle disposed within the capsule. The at least one electrophoretically-mobile particle has a second optical property different from the first optical property, and the at least one electrophoretically-mobile particle can change position within the capsule under the influence of an applied electric field. The appearance of the display element can change depending on where the at least one electrophoretically-mobile particle is situated within the capsule.
In another embodiment, the vapor-permeable electrode comprises an electrode permeable to water vapor. In another embodiment, the vapor-permeable electrode comprises a reticulated electrically conductive structure. The reticulated electrically conductive structure can be a wire mesh. The wire mesh can be made of copper or bronze, as well as other metals. The reticulated electrically conductive structure can be a reticulated layer at least partially coated with an electrically conductive material, or it can be a reticulated layer at least partially impregnated with an electrically conductive material.
In another aspect the invention relates to an electrostatically addressable display, including a display element having a first surface and a second surface, a protective layer disposed adjacent the first surface of the display element, the protective layer capable of transmitting charge, and an electrode disposed adjacent the second surface of the display element.
In one embodiment, the protective layer is flexible. In one detailed embodiment, the protective layer comprises an anisotropic material. For example, the protective layer can comprise a sheet of plastic and a plurality of conductive elements vertically embedded in the sheet. The conductive elements can comprise a plurality of rods. The conductive elements can be substantially invisible. Alternatively, the protective layer can comprise a semiconductor. For example, the protective layer can comprise a polymeric semiconductor including a plurality of photoconductors. The protective layer can is comprise a layer of polymeric material, such as Mylar.
In another embodiment, the display includes an electrophoretic display element that has as components a capsule, a dispersing fluid having a first optical property disposed within the capsule, and at least one electrophoretically-mobile particle disposed within the capsule. The at least one electrophoretically-mobile particle has a second optical pr

Affiliated with

Also associated with

Rating

Protective electrodes for electrophoretic displays does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Protective electrodes for electrophoretic displays, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protective electrodes for electrophoretic displays will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3208346