Electro-optic displays and driving methods
A driving method for driving an electrophoretic display comprising four types of particles, the first type of particles and the third type of particles are positively charged, and the second type of particles and the fourth type of particles are negatively charged, the method comprises the steps of: (i). applying a first driving voltage to the pixel of the electrophoretic display for a first period of time at a first amplitude to drive the pixel to a color state of the fourth type of particle at the viewing side; and (ii). applying a second driving voltage to the pixel of the electrophoretic display for a second period of time, opposite to that of the first driving voltage and a second amplitude smaller than that of the first amplitude, to drive the second type particle towards the non-viewing side.
1. A driving method for driving a pixel of an electrophoretic display comprising a first surface on a viewing side, a second surface on a non-viewing side, and an electrophoretic fluid disposed between a first light-transmissive electrode a second electrode, the electrophoretic fluid comprising a first type of particles, a second type of particles, a third type of particles, and a fourth type of particles, all of which are dispersed in a solvent, wherein
a. the four types of pigment particles have different optical characteristics;
b. the first type of particles and the third type of particles are positively charged, wherein the first type of particles have a greater magnitude of positive charge than the third particles; and
c. the second type of particles and the fourth type of particles are negatively charged, wherein the second type of particles have a greater magnitude of negative charge than the fourth particles;
the method comprises the steps of:
(i). applying a first driving voltage to the pixel of the electrophoretic display for a first period of time at a first amplitude to drive the pixel to a color state of the second type of particle at the viewing side; and
(ii). applying a second driving voltage to the pixel of the electrophoretic display for a second period of time, opposite to that of the first driving voltage and a second amplitude smaller than that of the first amplitude, to drive the fourth type particle towards the non-viewing side, wherein the second period of time is longer than the first period of time, and wherein the color state of the second type of particles is retained in the viewing side after the application of the second voltage.
2. The driving method of claim 1 , further comprising repeating steps (i) and (ii).
3. The driving method of claim 2 , wherein steps (i) and (ii) are repeated at least 3 times.
4. The driving method of claim 1 further comprising applying no voltage to the pixel for a period of time before step (i).
5. The driving method of claim 1 , wherein the amplitude of the second driving voltage is less than 50% of the amplitude of the first driving voltage.
6. A driving method for driving a pixel of an electrophoretic display comprising a first surface on a viewing side, a second surface on a non-viewing side, and an electrophoretic fluid disposed between a first light-transmissive electrode a second electrode, the electrophoretic fluid comprising a first type of particles, a second type of particles, a third type of particles, and a fourth type of particles, all of which are dispersed in a solvent, wherein
a. the four types of pigment particles have different optical characteristics;
b. the first type of particles and the third type of particles are positively charged, wherein the first type of particles have a greater magnitude of positive charge than the third particles; and
c. the second type of particles and the fourth type of particles are negatively charged, wherein the second type of particles have a greater magnitude of negative charge than the fourth particles;
the method comprises the steps of:
(i) applying a first driving voltage to the pixel of the electrophoretic display for a first period of time at a first amplitude to drive the pixel to a color state of the third type of particle at the viewing side;
(ii) applying a second driving voltage to the pixel of the electrophoretic display for a second period of time at a second amplitude to drive the pixel to a color state of the second type of particle at the viewing side; and
(iii) applying a third driving voltage to the pixel of the electrophoretic display for a third period of time, opposite to that of the second driving voltage and a third amplitude smaller than that of the second amplitude, to drive the fourth type particle towards the non-viewing side,
wherein the third period of time of step (iii) is longer than the second period of time in step (i), and wherein the color state of the second type of particles is retained in the viewing side after the application of the third voltage.
7. The driving method of claim 6 further comprising applying no driving voltage to the display pixel for a fourth period of time after the step (i).
8. The driving method of claim 6 , wherein step (i) is repeated at least 5 times.
9. The driving method of claim 2 , wherein steps (ii) and (iii) are repeated at least 3 times.
10. The driving method of claim 6 , wherein the amplitude of the third driving voltage is less than 50% of the amplitude of the second driving voltage.