Methods for driving electro-optic displays, and apparatus for use therein

A method for addressing a bistable electro-optic medium, the electro-optic medium being an encapsulated dual particle opposite charge type medium comprising two different types of particles bearing opposite charges, the method comprising:

• (a) applying to the medium a first alternating current pulse having a first voltage, a first frequency and a first duty cycle, for a period sufficient to cause the medium to display a substantially constant first gray level;
• and
• (b) applying to the medium a second alternating current pulse having the first voltage and the first frequency but a second duty cycle different from the first duty cycle, for a period sufficient to cause the medium to display a substantially constant second gray level different from the first gray level.