Patent ID: 8593376

Claim:
An active matrix electroluminescent display device comprising a matrix array of electroluminescent display elements each of which has an associated switching unit configured to control the current through the display element, wherein the switching unit 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 continuously connected to the supply line via a storage capacitor and being connected 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, wherein the display elements are arranged in rows and columns, wherein half the current mirror circuit including only one of the first transistor and the second transistor is shared among the switching units of all the display elements in a same column, wherein the switch device is controlled by a first waveform provided on a first row and the supply line is second row which is adjacent to the first row and is configured to provide a second waveform, wherein the first and second waveforms have a similar shape including a first pulse having a first amplitude and a second pulse having a second amplitude, the second amplitude being higher than the first amplitude, and wherein the second waveform is delayed with respect to the first second so that a leading edge of the second pulse of the first waveform coincides with a leading edge of the first pulse of the second waveform.