Threshold addressing of electrophoretic displays
First Claim
1. A method of addressing an electrophoretic display, the method comprising the steps of:
- (a) providing an electrophoretic display comprising a plurality of display elements, each of the display elements comprising;
an encapsulating wall;
a plurality of particles disposed within the encapsulating wall, at least one of the plurality of particles responsive to an applied electric field; and
a carrier medium disposed within the encapsulating wall; and
(b) providing a first voltage across at least one of said display elements, thereby to change a viscosity of the carrier medium; and
(c) providing a second voltage across at least one of said display elements, thereby to cause at least one particle to move within the element, wherein the particles are substantially immobile under the second voltage without application of the first voltage.
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Accused Products
Abstract
Methods and apparatus for an electrophoretic display in which the particle motion is a controlled, non-linear function of the applied electric field. Threshold addressing allows simple, inexpensive passive addressing techniques to be employed. The inverse electrorheological gating techniques allow the construction of a full color, passively addressed display without the need to address individual capsules. A mixture of capsules is coated randomly onto a substrate enabling the creation of inexpensive displays. All the techniques allow a significant threshold to be realized. Rapid movement of the pigment particles above the threshold allows rapid switching times for the display. Since diffusion and gravity are extremely weak forces compared to the yield stresses created, the structured or gelled medium approach provides a great improvement in the bistability of the displays.
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Citations
16 Claims
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1. A method of addressing an electrophoretic display, the method comprising the steps of:
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(a) providing an electrophoretic display comprising a plurality of display elements, each of the display elements comprising;
an encapsulating wall;
a plurality of particles disposed within the encapsulating wall, at least one of the plurality of particles responsive to an applied electric field; and
a carrier medium disposed within the encapsulating wall; and
(b) providing a first voltage across at least one of said display elements, thereby to change a viscosity of the carrier medium; and
(c) providing a second voltage across at least one of said display elements, thereby to cause at least one particle to move within the element, wherein the particles are substantially immobile under the second voltage without application of the first voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electrophoretic display element exhibiting a voltage below which the element will not change condition, the display element comprising:
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an encapsulating wall;
a plurality of particles disposed within the encapsulating wall, at least one of the plurality of particles responsive to an applied electric field; and
a carrier medium disposed within the encapsulating wall, the carrier medium having a substantial resistance to particle movement under a second voltage and substantially lacking resistance to particle movement upon applying both the second voltage and a first voltage. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An electrophoretic display element exhibiting a voltage threshold below which the element will not change condition, the display element comprising:
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an encapsulating wall;
a plurality of particles disposed within the encapsulating wall, at least one of the plurality of particles responsive to an applied electric field; and
a carrier medium disposed within the encapsulating wall, wherein the carrier medium has a substantial resistance to particle movement at a voltage below a threshold voltage and substantially lacks resistance to particle movement at or above the threshold voltage such that at a voltage at or above the threshold voltage the particles exhibit movement at a velocity representing substantially a step-change in particle velocity relative to particle velocity at a voltage below the threshold voltage.
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15. A method of threshold addressing an electrophoretic display, the method comprising the steps of:
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(a) providing an electrophoretic display comprising a plurality of display elements, each of the display elements comprising;
an encapsulating wall;
a plurality of particles disposed within the encapsulating wall, at least one of the plurality of particles responsive to an applied electric field; and
a carrier medium disposed within the encapsulating wall; and
(b) providing a voltage of at least a threshold voltage across at least one of said display elements, thereby to cause at least one particle to move within the element, wherein the threshold voltage represents a value of voltage below which the carrier medium has a substantial resistance to particle movement such that the particles are substantially immobile and at or above which the carrier medium substantially lacks resistance to particle movement such that the particles move at a velocity representing substantially a step-change in particle velocity relative to particle velocity when the voltage is below the threshold voltage.
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16. An electrophoretic display element exhibiting a voltage threshold below which the element will not change condition, the display element comprising:
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an encapsulating wall;
a plurality of particles disposed within the encapsulating wall, at least one of the plurality of particles responsive to an applied electric field; and
a carrier medium disposed within the encapsulating wall, wherein the carrier medium has a substantial resistance to particle movement at a voltage below a threshold voltage and substantially lacks resistance to particle movement at or above the threshold voltage such that at or above the threshold voltage the particles exhibit movement at a velocity representing substantially a step-change in particle velocity relative to particle velocity at a voltage below the threshold voltage and wherein the particles move at a velocity that is non-linearly related to an applied voltage.
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Specification