Patent ID: 11868020
Assignee: E INK CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 12:
13. A method for driving an electrophoretic display device comprising:
(i) providing an electrophoretic display device comprising (a) a layer of the electrophoretic medium, said electrophoretic medium comprising a fluid and first, second, third and fourth types of particles dispersed in the fluid, the first, second, third and fourth types of particles having respectively first, second, third and fourth colors differing from one another, the first and third types of particles having charges of one polarity and the second and fourth types of particles having charges of the opposite polarity, the first type of particles having a greater zeta potential or electrophoretic mobility than the third type of particles, and the second type of particles having a greater zeta potential or electrophoretic mobility than the fourth type of particles, wherein one of the types of particles is white and the other three types of particles are non-white, one of the types of non-white particles is partially light-transmissive, and the remaining two types of non-white particles are light-reflective, wherein a layer of the partially light-transmissive type of particles has a contrast ratio of not more than about 0.5, (b) a front electrode and a rear electrode disposed on opposed sides of the layer of electrophoretic medium, and (c) voltage control means arranged to control the potentials of the front and rear electrodes;
(ii) applying a second driving voltage having a polarity driving partially light-transmissive type of particles towards the viewing surface for a third period of time;
(iii) applying a third driving voltage have a polarity opposite to that of the second driving voltage and a magnitude less than that of the second driving voltage for a fourth period of time longer than the third period of time;
(iv) repeating steps (ii) and (iii);
(v) after the repetition of steps (ii) and (iii), applying the third driving voltage for a fifth period of time;
(vi) applying no driving voltage for a sixth period of time;
(vii) repeating steps (v) and (vi);
(viii) after the repetition of steps (v) and (vi), applying the second driving voltage for a seventh period of time;
(ix) applying a fourth driving voltage having the same polarity as, but a smaller magnitude than, the third driving voltage for an eighth period of time longer than the seventh period of time; and
(x) repeating steps (viii) and (ix), but concluding with a repetition of step (viii) not followed by a repetition of step (ix), thereby displaying the color of the light-transmissive type of particles at the viewing surface.