Patent ID: 8139039

Claim:
A selectively erasable electronic writing tablet comprising: a transparent, flexible writing surface; electrically conductive layers below said writing surface, adjacent said conductive layers being spaced apart by a gap; a layer of cholesteric liquid crystal material disposed in said gap, wherein pressure applied to said writing surface decreases said gap; circuitry including: a) a full erase function adapted to apply a full erase voltage to said conductive layers placing said liquid crystal layer in an initial planar or focal conic texture that is stable in an absence of an electric field, b) a write function adapted to form a written portion on said writing tablet during writing conditions, including applying said pressure to said writing surface, wherein said written portion includes a changed focal conic or planar texture different from said initial texture without affecting a texture outside of said written portion; c) a select erase function adapted to selectively erase said written portion during select erasing conditions, including applying said pressure to an erasing region of said writing surface overlying said written portion, wherein said selectively erasing returns said changed texture to said initial texture without affecting a texture outside of said erasing region; and a black or color light absorbing layer located so as to absorb light passing through said liquid crystal layer.