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

Claim 0:
1. An 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.