US Patent 6987603 Construction of electrophoretic displays

An electrophoretic display (100) comprises a front light-transmissive substrate (112), a rear substrate (116) spaced from the front substrate (112) so as to leave a cavity, and an electrophoretic medium (102) in the cavity, the electrophoretic medium (102) comprising a liquid external phase (120) and a plurality of capsules (104) suspended in the liquid external phase (120), each of the capsules comprising a capsule wall, a suspending fluid (106) held within the capsule wall and at least one electrically charged particle (108, 110) suspended in the suspending fluid (106).