Driving methods for electrophoretic displays
The present invention is directed to driving methods for driving an electro-optic display device which can display high quality color states. The electro-optic display may have a plurality of display pixels, a first type of pigment particle, a second type of pigment particle, and a third type of pigment particle, wherein the three types of pigment particles have optical characteristics differing from one another, the method may include: (i) driving a display pixel to the color state of the first type of pigment particles or the color state of the second type of pigment particles; (ii) driving the pixel to a grey state between the color state of the first type of pigment particle and the color state of the second type of pigment particles; and (iii) applying at least one pair of opposite driving pulses.
1. A driving method for driving an electro-optic display having a plurality of display pixels, and an electrophoretic fluid comprising a first type of pigment particle, a second type of pigment particle, and a third type of pigment particle, wherein
(a) the three types of pigment particles have optical characteristics differing from one another,
(b) the first type of pigment particles and the second type of pigment particles carry opposite charge polarities; and
(c) the third type of pigment particles carries a lower charge intensity than the first type of pigment particles or the second type of pigment particles;
the method comprising the following steps, in this order:
(i) driving a display pixel to the color state of the first type of pigment particles or the color state of the second type of pigment particles;
(ii) immediately after the completion of step (i), driving the pixel to a grey state between the color state of the first type of pigment particle and the color state of the second type of pigment particles; and
(iii) immediately after the completion of step (ii), applying a shaking waveform comprising at least one pair of opposite driving pulses, wherein at the end of the shaking waveform the three types of pigment particles are mixed in the electrophoretic fluid.
2. The method of claim 1 , wherein the first type of pigment particles is negatively charged and the second type of pigment particles is positively charged.
3. The method of claim 1 , wherein the three types of pigment particles have different colors.
4. The method of claim 1 , wherein the first type of pigment particles is white and the second type of pigment particles is black.
5. The method of claim 1 , wherein the third type of pigment particles is non-white and non-black.
6. The method of claim 1 , wherein the third type of pigment particles is red.
7. The method of claim 1 , following the step of applying at least one pair of opposite driving pulses, applying a driving voltage having the same polarity as the first type of pigment particles to drive the pixel to the color state of the first type of pigment particles at the viewing side.
8. The method of claim 1 , following the step of applying at least one pair of opposite driving pulses, applying a driving voltage having the same polarity as the second type of pigment particles to drive the pixel to the color state of the second type of pigment particles at the viewing side.
9. The method of claim 1 , following the step of applying at least one pair of opposite driving pulses, applying a driving voltage having the same polarity as the third type of pigment particles to drive the pixel to the color state of the third type of pigment particles at the viewing side.
10. The method of claim 1 , wherein the step of driving the pixel to a grey state comprises applying a first driving voltage to the pixel in the color state of the first type of pigment particles for a first period of time, wherein the first driving voltage has the same polarity as the second type of pigment particles.
11. The method of claim 1 , wherein the step of driving the pixel to a grey state comprises applying a second driving voltage to the pixel in the color state of the second type of pigment particles for a second period of time, wherein the second driving voltage has the same polarity as the first type of pigment particles.