Patent ID: 8200536

Claim:
An image display medium comprising: a pair of substrates facing each other; and a particle group comprising two or more types of particles sealed in a space between the substrates, at least one of the two or more types of particles being positively chargeable by an external stimulus and at least one other of the two or more types of particles being negatively chargeable by an external stimulus, and the positively chargeable and negatively chargeable particles having, respectively, colors different from each other, wherein the positively chargeable and negatively chargeable particles have particle size distributions satisfying the following formula (1): 0.4 <Ds/Dl< 0.9 Formula (1) wherein, from among the positively chargeable and negatively chargeable particles, Ds represents the particle size distribution of at least one type of particles which are charged with one polarity, from among the positively chargeable and negatively chargeable particles, Dl represents the particle size distribution of at least one other type of particles which are charged with the other polarity, Ds and Dl invariably satisfy a relationship of Ds<Dl, a particle size distribution D expressed by Ds or Dl represents a ratio (d10 vol/d90 vol) of 10% volume diameter (d10 vol) to 90% volume diameter (d90 vol), and 10% volume diameter (d10 vol) and 90% volume diameter (d90 vol) invariably satisfy a relationship of d90 vol≦d10 vol.