Electrophoretic display device
First Claim
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1. An electrophoretic display having a viewing surface and comprising an electrophoretic medium and means for applying an electric field to the electrophoretic medium, the electrophoretic medium comprising a fluid and first, second and third types of particles dispersed in the fluid, wherein:
- (i) the first and second types of particles bear charges of opposite polarities and have first and second optical characteristics differing from each other;
(ii) the third type of particles has substantially the first optical characteristic and bears a charge of the same polarity as the second type of particles but have a lower zeta potential or electrophoretic mobility than the second type of particles; and
(iii) when the first optical characteristic is displayed at the viewing surface, application for a time T of an electric field E of a polarity which drives the second type of particles towards the viewing surface will cause the second optical characteristic to be displayed at the viewing surface, but application for a time T of an electric field E/3 of the same polarity will cause the first optical characteristic to remain displayed at the viewing surface.
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Abstract
An electrophoretic display is provided suitable for passive matrix driving. The electrophoretic display comprises three types of particles, with the first and second types of charged particles carrying charges of opposite polarities and have contrasting colors. The third type of particles has the same color as the first or the second type of particles.
258 Citations
16 Claims
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1. An electrophoretic display having a viewing surface and comprising an electrophoretic medium and means for applying an electric field to the electrophoretic medium, the electrophoretic medium comprising a fluid and first, second and third types of particles dispersed in the fluid, wherein:
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(i) the first and second types of particles bear charges of opposite polarities and have first and second optical characteristics differing from each other; (ii) the third type of particles has substantially the first optical characteristic and bears a charge of the same polarity as the second type of particles but have a lower zeta potential or electrophoretic mobility than the second type of particles; and (iii) when the first optical characteristic is displayed at the viewing surface, application for a time T of an electric field E of a polarity which drives the second type of particles towards the viewing surface will cause the second optical characteristic to be displayed at the viewing surface, but application for a time T of an electric field E/3 of the same polarity will cause the first optical characteristic to remain displayed at the viewing surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification