Addressing methods for displays having zero time-average field

A method for addressing a bistable display, said display comprising a set of display elements each having first and second display states differing in at least one optical property, the method comprising:

• (a) selecting a first subset of display elements that represent a first image, and applying to said first subset a first addressing signal, thereby causing said first subset to assume said first display state and said display to display said first image;
• (b) selecting a second subset of display elements that represent a second image different from said first image and thereby defining three classes of display elements, namely a first class which are members of both the first and second subsets, a second class which are members of said first subset but not members of said second subset, and a third class which are not members of said first subset but are members of said second subset, and applying to said second class a second addressing signal, thereby setting said second class to said second display state, and applying to said third class a third addressing signal, thereby setting said third class to said first display state, and causing said display to display said second image.

A bistable display element having first and second display states differing in at least one optical property, the display element comprising:

• a signal control module that controls the signal applied to said display element, said signal control module applying at least a first addressing signal and at least a second addressing signal to said display element, said first addressing pulse not substantially changing the display state of said element and said second addressing signal changing said display state of said element,
• wherein said signal control module applies said first addressing signal having a first polarity, a first amplitude as a function of time and a first duration, and said second addressing signal having a second polarity, a second amplitude as a function of time and a second duration, such that the sum of the first amplitude as a function of time integrated over the first duration and the second amplitude as a function of time integrated over the second duration is substantially zero.