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ELECTRODE AND FILM SURFACE STRUCTURE FOR EXPRESSIVE WRITING CAPABILITY IN AN ELECTROSTATIC RE-WRITEABLE MEDIUM DEVICE

IP.com Disclosure Number: IPCOM000124196D
Publication Date: 2005-Apr-11

Publishing Venue

The IP.com Prior Art Database

Abstract

An electrostatic re-writable medium comprises a surface layer and/or has a surface that effectively supports expressive writing, and/or the electrode comprises a surface layer and/or has a surface that effectively supports expressive writing, that is to say allows for creastion of lines having variable width, gray level or pattern.

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  ELECTRODE AND FILM SURFACE STRUCTURE FOR EXPRESSIVE WRITING CAPABILITY IN AN ELECTROSTATIC RE-WRITEABLE MEDIUM DEVICE

The present invention relates to electronic displays and, in particular, to apparatus and methods for addressing a display with an input instrument, e.g., a stylus.

Electrostatic re-writable media (ERM) typically include a stack of layers of materials. For example, one of the layers can be an electrophoretic display medium, and a layer at the bottom of the stack can be a common plane electrode. A charge is applied to the top surface with an electrode at a voltage different from the voltage of the common plane. The charges can cause electrophoretic movement that results in an image that tracks the electrode movement. The optical state can be affected by the sign of the electrode voltage so that, by reversing the voltage of the electrode, an image can be erased or the opposite optical state can be formed. For example, contact with the electrode at a positive voltage relative to the common plane can result in a white optical state, and by reversing the electrode voltage a dark state can be formed. It is a technical challenge to produce an ERM-based display that permits "expressive" writing; that is, creation of lines having, for example, variable width, gray level, and pattern.

In the accompanying drawings:

Figures 1 and 2 are cross-sectional views of displays and their associated styli for addressing the displays.

Figure 3 is a side elevation of an embossed top surface of a display.

Figures 4 and 5 are side elevations of embossed top surfaces of displays and their associated styli.

Figures 6-10 show various views of different types of styli.

General Principles of Electro-optic Displays

Electro-optic displays include a layer of electro-optic material, a term which is used herein in its conventional meaning in the art to refer to a material having first and second display states differing in at least one optical property, the material being changed from its first to its second display state by application of an electric field to the material. The optical property is typically color perceptible to the human eye, but may be another optical property, such as optical transmission, reflectance, luminescence or, in the case of displays intended for machine reading, pseudo-color in the sense of a change in reflectance of electromagnetic wavelengths outside the visible range.

The electro-optic displays in which the method of the present invention is used typically contain an electro-optic material which is a solid in the sense that the electro-optic material has solid external surfaces, although the material may, and often does, have

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internal liquid- or gas-filled space. Such displays using solid electro-optic materials may hereinafter for convenience be referred to as "solid electro-optic displays".

Several types of electro-optic displays are known. One type of electro-optic display is a rotating bichromal m...