Writing system including paper-like digitally addressed media and addressing device therefor

Claim 1

A writing system including a reusable planar writing sheet for use with an addressing device which is capable of imposing human perceivable information on said writing sheet, said writing sheet and said addressing device being normally independent and remote from one another when said writing sheet is not being addressed, and wherein said writing sheet and said addressing device are brought into proximity with and are moved relative to one another for imposing information on said writing sheet, said writing sheet has a surface upon which information can be written and erased, exhibits ambient light valve behavior, has the ability to retain imposed information in the absence of an external retaining ibrce, and has the capability of being rolled into tubular form about any axis lying in the plane of said sheet, said writing sheet further comprises a light transparent host layer, a plurality of reorientable substantially spherical balls having at least two dissimilar surface portions of contrasting colors and different surface charges, each of said balls being contained, and free to rotate, within a cavity in said host layer, said reorientable balls being movable from a fixed and stable first orientation, in which they will present a first visual appearance, to a fixed and stable second orientation, in which they will present a second visual appearance, said addressing device includes an array of electrically chargeable electrodes for dislodging said balls from one fixed and stable orientation and initiating rotation thereof, and a holding electrode for completing rotation of said balls to the other fixed and stable orientation.