Encapsulated bichromal gyricon display

Abstract

Various layered arrays utilizing encapsulated bichromal balls are disclosed that can be used in display applications. Also disclosed are related methods for manufacturing the layered arrays, and forming displays. The methods are particularly well-suited for forming displays having one or more monolayer(s) of closely-packed encapsulated bichromal balls.

Description

BACKGROUND [0001] The present disclosure relates to displays based upon encapsulated bichromal balls and methods of manufacturing such displays. It finds particular application in conjunction with display technology, and “electric paper” and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications. [0002] Bichromal balls or beads as sometimes referred to in the art, are small spherical balls which have an optical and an electrical anisotropy. These characteristics generally result from each hemisphere surface having a different color and electrical charge. [0003] These spherical particles are imbedded in a solid substrate and a slight space between each ball and the substrate is filled with an oil so that the balls are free to rotate, and migrate in an oil-filled cavity, in a changing electrical field. If one hemisphere is black and the other is white, each pixel can be tur...

AI Technical Summary

Benefits of technology

The present patent is about methods and compositions for producing a closely-packed bichromal Gyricon display with enhanced optical characteristics. The display member comprises a substrate, a layer of adhesive, and a monolayer of encapsulated bichromal balls applied to the adhesive using a cascading application process. The resulting display exhibits improved uniformity and close-packing of the bichromal balls, critical factors for achieving maximum optical performance. The process for forming a layered array of bichromal balls involves depositing a plurality of encapsulated bichromal balls on a substrate using a cascading application process. The resulting display assembly includes a supporting substrate, multiple layers of bichromal balls, and a protective cover. The transmission optical contrasts of the monolayers of bichromal balls produced by the processes disclosed herein are from about 0.40 to about 0.70, allowing only a small percentage of incident light to transmit through the monolayers. The displays produced utilizing such closely-packed bichromal balls exhibit enhanced optical contrast.

Problems solved by technology

Fabrication of the Gyricon display sheet involves many complicated steps.

The material into which the balls are disposed or embedded is largely limited to the class of elastomeric materials chosen for their large capacity to swell.

This material is costly.

The disadvantage of the multi-layered structure is that it degrades the contrast, i.e. reflectance, degrades the resolution, increases the switching voltage, and increases the complexity and cost of the driver electronics of the display.

These add to the complexity and cost of the resulting Gyricon display.

However, such randomly dispersed balls are not closely-packed and produce a large amount of open space.

This results in decreased optical contrast.

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