Reversible image display medium

摘要

A reversible image display medium accommodates a dry developer in each cell formed between two substrates. The developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities. An image display can be achieved by forming an electrostatic latent image on one of the substrates to drive the developing particles in an electric field based on the electrostatic latent image. The developing particles are set to an average charge quantity of 1.0 muC/g to 10 muC/g to achieve good image display. Optionally at least one kind of the developing particles are magnetic developing particles having a coercive force of 50 oersteds to 250 oersteds, and optionally having an optical reflection density of 1.0 or more. An amount of small-size developing particles and/or an addition of a third component may be adjusted and volume average particle size ratio of developing particles may be controlled.