Active matrix electroluminescent display devices, and their manufacture

Abstract

Physical barriers () are present between neighbouring pixels () on a circuit substrate () of an active-matrix electroluminescent display device, particularly with LEDs () of organic semi conductor materials. The invention forms these barriers () with metal or other electrically-conductive material (), that is insulated () from the LEDs but connected to the circuitry within the substrate (). This conductive barrier material () backs-up or replaces at least a part of the drive supply line () to which the LEDs are connected by a drive element T. This transfers the problem of line resistance and associated voltage drop from within the circuit substrate (), where it is severely constrained, to the much freer environment of the pixel barriers () on the substrate () where the conductive barrier material () can provide much lower resistance. Very large displays can be made with low voltage drops along this composite drive supply line (). Furthermore, the structure can be optimised to form a smoothing capacitor (Cs) between this drive supply line () with its conductive barrier material () and the further supply line () of the LED upper electrodes () extending on an insulating coating () over the top of the conductive barrier material ().