Color electrophoretic displays using same polarity reversing address pulse
An electrophoretic display comprising a fluid including a first species of particles and a charge control agent disposed between first and second electrodes. When a first addressing impulse have an electrical polarity is applied to the medium, the first species of particles move in one direction relative to the electric field, but when a second addressing impulse, larger than the first addressing impulse but having the same electrical polarity, is applied to the medium, the first species of particles move in the opposed direction relative to the electric field.
1. An electrophoretic medium comprising a fluid and first, second, and third species of particles disposed in the fluid,
wherein the second and third species of particles bear charges of opposite polarities and the first species of particles bears a charge of the same polarity as the third species of particles, and wherein the colors of the three species are different,
wherein when the electrophoretic medium is addressed with a first impulse in a first direction, the first species of particles move in a first direction relative to an electric field of the first impulse, and a viewing surface of the electrophoretic medium displays the color of the third species of particle,
wherein when the electrophoretic medium is addressed with a second impulse larger than the first impulse and having the same polarity as the first impulse, the first species of particles move in a second direction that is opposite to the first direction, and the viewing surface displays a mixture of the first and third particles, and
wherein when the electrophoretic medium is addressed with a third impulse greater than the second impulse, but having the same polarity as the first and second impulses, the viewing surface displays a mixture of the first, second and third particles.
2. The electrophoretic medium of claim 1 , wherein the fluid is dyed a color.
3. The electrophoretic medium of claim 2 , wherein one of the dyed fluid and the first, second, and third species of particles has one of the additive primary colors and another of the dyed fluid and the first, second, and third species of particles has the complementary subtractive primary color.
4. The electrophoretic medium of claim 3 , wherein the first species of particles is white, and the dyed fluid or the second species of particles has an additive primary colors and the other of the dyed fluid and the second species of particles has a subtractive primary color complementary to the additive primary color.
5. The electrophoretic medium according to claim 1 , wherein the fluid is uncolored.
6. The electrophoretic medium according to claim 5 , wherein the second and third species of particles are white and black.
7. The electrophoretic medium according to claim 1 , wherein the first, second, or third species of particles is white and the colors of the other two species of particles and the fluid are selected from yellow, cyan and magenta, in any order.
8. The electrophoretic medium according to claim 1 , wherein the particles and the fluid are confined within a plurality of capsules or microcells.
9. The electrophoretic medium according to claim 1 , wherein the particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material.
10. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive incorporating the electrophoretic display according to claim 1 .