Patent ID: 6359605
Filing Date: 2002-03-19
Classification: G09G

Abstract:
An active matrix electroluminescent display device comprising a matrix array of electroluminescent display elements each of which has an associated switching means for controlling the current through the display element, characterised in that the switching means associated with a display element comprises a current mirror circuit which is operable to sample and store a drive signal that determines the display element drive current applied during a display element address period, and to maintain the display element drive current following the address period, the current mirror circuit comprising a first transistor whose current-carrying electrodes are connected between a supply line and an electrode of the display element, a second transistor to whose gate electrode and first current-carrying electrode the drive signal is applied and whose second current-carrying electrode is connected to the supply line, the gate of the first transistor being connected to the supply line via a storage capacitor and to the gate of the second transistor via a switch device which is operable to connect the gates of the first and second transistors during the address period;further characterised in that the display elements are arranged in rows and columns, and the switch devices of the current mirror circuits for a row of display elements are connected to a respective common, row address conductor via which a selection signal for operating the switch devices in that row is applied, and each row address conductor is arranged to receive a selection signal in turn, characterised in that each row or column of display elements is associated with a respective supply line which is shared by all the display elements in the row or column, and further characterised in that the supply line is associated with, and common to, a row of display elements and comprises a row address conductor associated with an adjacent row of display elements via which a selection signal is applied to the switch devices of the current mirror circuits of the adjacent row.