GB788479A - Improvements in or relating to electroluminescent cells - Google Patents

Abstract

788,479. Electroluminescence. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Oct. 21, 1955 [Nov. 1, 1954], No. 30130/55. Class 39(1). Electroluminescent particles embedded in dielectric material are oriented in groups perpendicular to the parallel electrodes of the cell by applying an aligning electric field whilst the dielectric is in a fluid condition. Heat is applied simultaneously with the orienting field to render fluid the thermoplastic and thermosetting dielectrics. Polyester epoxy, acrylic and styrene resins are satisfactory thermosetting dielectrics. Canada balsam, polymerized ethyl methacrylate or polyvinyl acetate are suitable thermoplastic materials. The alignment apparatus for a cell comprising a backing plate 22, electrode 20, high dielectric constant layer 18, e.g., mica, phosphor-dielectric layer 16 and subsequently a further electrode layer with bus-bar terminals, consists of spacers 27 placed on the layer 18 to confine the phosphor dielectric suspension. A heater 26 is placed on top of the assembly and a field applied between the heater and the electrode 20. The phosphor dielectric may be introduced when the heater is already in position by means of the overflow ports 28. The alignment of the phosphor particles in the fluid dielectric is thought to be primarily a dielectric phenomenon. Dielectric materials which polymerize at room temperature, e.g. water emulsified acrylic resins or epoxy resins, may also be used thereby dispensing with the heating step.