Electrophoretic display including display medium containing gelling agent for image stability
First Claim
1. A method of forming an image in an electrophoretic display device comprising an electrophoretic display layer located between two conductive film substrates, at least one of which is transparent, wherein the electrophoretic display layer includes therein a multiplicity of individual units that contain a display medium, wherein the display medium comprises a liquid system, at least one thermally reversible gelling agent, and at least one set of particles exhibiting a color, the method comprising heating the display device to a temperature of about or above a melting point of the at least one thermally reversible gelling agent, subsequently forming an image in the display device by selective application of an appropriate field to selected ones of the multiplicity of individual units to move the at least one set of particles within the heated display medium, and subsequently cooling the display device to a temperature of about or below a gel point of the at least one thermally reversible gelling agent to fix the image in a gel state.
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Abstract
A display medium for an electrophoretic display device includes a liquid system, at least one thermally reversible gelling agent, and at least one set of particles exhibiting a color. Inclusion of the gelling agent enables an image formed in the display device at an elevated temperature of about or above the melting point of the gelling agent to be fixed in a gel state, e.g., at temperature of about or below a gel point of the gelling agent. The image thus has stability, even in the absence of an applied electrophoretic field.
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Citations
13 Claims
- 1. A method of forming an image in an electrophoretic display device comprising an electrophoretic display layer located between two conductive film substrates, at least one of which is transparent, wherein the electrophoretic display layer includes therein a multiplicity of individual units that contain a display medium, wherein the display medium comprises a liquid system, at least one thermally reversible gelling agent, and at least one set of particles exhibiting a color, the method comprising heating the display device to a temperature of about or above a melting point of the at least one thermally reversible gelling agent, subsequently forming an image in the display device by selective application of an appropriate field to selected ones of the multiplicity of individual units to move the at least one set of particles within the heated display medium, and subsequently cooling the display device to a temperature of about or below a gel point of the at least one thermally reversible gelling agent to fix the image in a gel state.
Specification