Patent ID: 8405599

Claim:
An image display medium comprising: a pair of substrates, at least one of which is light-transmissive; two or more kinds of particles, including a first kind of particle and a second kind of particle, having different colors and charge polarities, the particles being positioned between the pair of substrates such that the particles can move in response to an electric field generated between the pair of substrates; and an electric charge-retention layer that retains a positive or negative charge, is provided at a side of each of the pair of substrates, and maintains the same polarity at each of the pair of substrates, wherein the electric charge-retention layer retains the positive or negative charge and is provided at the side of at least one of the pair of substrates so that an absolute value of a voltage at which the first kind of particle terminates movement from a side of a first substrate of the pair of substrates towards a side of a second substrate of the pair of substrates is smaller than an absolute value of a voltage at which the second kind of particle initiates movement from the side of the second substrate towards the side of the first substrate, and an absolute value of a voltage at which the first kind of particle terminates movement from the side of the second substrate towards the side of the first substrate is smaller than an absolute value of a voltage at which the second kind of particle initiates movement from the side of the first substrate towards the side of the second substrate.