Memory-equipped monochrome display of the photoconductor-electroluminescent type

Claim 1

Electroluminescent monochrome display with a memory effect comprising on an insulating substrate an assembly having a single electroluminescent layer (16, 34) in contact with a photoconductor layer (20, 32) or separated from said photoconductor layer by a first transparent dielectric layer (18), said assembly of said two layers being inserted between a first (36) and a second (30) systems of electrodes connected to a power supply (24) for exciting certain zones of the electroluminescent layer, said photoconductor layer (32) being such that the overlap zone of the light sensitivity spectrum of said photoconductor layer and the emission spectrum of the ambient illumination is at a minimum and said electroluminescent layer (34) being such that the overlap zone of said sensitivity spectrum and the emission spectrum of the electroluminescent layer is at a maximum, the emission spectrum of the electroluminescent layer overlapping also the visible spectrums and an optical filter (40) located between the electroluminescent layer (34) and the display observer and permitting the passage of that part of the emission spectrum of the electroluminescent layer most useful for display purposes, while blocking a region of the emission spectrum of the ambient illumination, the sensitivity spectrum of the photoconductor layer (32) being essentially contained in said region.