GB1381394A - Electrochemical display apparatus - Google Patents

Abstract

1381394 Matrix displays INTERNATIONAL BUSINESS MACHINES CORP 21 Feb 1972 [29 March 1971] 7894/72 Heading G5C [Also in Division H4] A display apparatus comprises one or more electrically common reference electrodes 24, one or more selectively addressable display electrodes 13, 17, e.g. forming a " figure of eight ", and an electrolyte medium 21 comprising an organic ionic halide, so that on passage of current of the appropriate polarity a halogen is released at the display electrode and obscures the surface thereof, which is otherwise visible. The display electrode surface is chemically inert to the halogen and to other components of the medium 21 whether in their oxidized or reduced form. As particularly described, the display electrode has a highly reflective surface, and the organic ionic halide is an ammonium, phosphonium, or arsonium iodide. Most detail is given of the ammonium compounds, the four substituents being the same or different and selected from hydrogen, alkyl, aryl and aralkyl, preferred compounds being acetyl-, propionyl-, and butyryl-choline iodide. The benzoyl derivative is also mentioned. Medium 21 may be liquid, with a viscosity controlled by the addition of gelatine (to prevent diffusion of the iodide or iodine) or it may form a gel therewith. The electrode 24 is preferably Ag/AgI.