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US 6,373,454 B1Granted
Active matrix electroluminescent display devices
AssigneeU.S. Philips Corporation
InventorsAlan G. Knapp, Neil C. Bird
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AssigneeU.S. Philips Corporation
InventorsAlan G. Knapp, Neil C. Bird
Estimating the term…
An active matrix electroluminescent display device has an array of current-driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (30, 32, 38) in which the same transistor (30) is used to both sense and produce the required drive current for the display element (20) with the gate of the transistor being connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. This allows variations in transistor characteristics over the array to be compensated and improved uniformity of light outputs from the display elements to be obtained.
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 in accordance with an applied drive signal and in which the switching means comprises a drive transistor whose first current-carrying terminal is connected to a first supply line, whose second current-carrying terminal is connected via the display element to a second supply line and whose gate is connected to its first current-carrying terminal via a capacitance, wherein the second current-carrying terminal of the drive transistor is connected to an input terminal for the drive signal and wherein a switch device is connected in series between the second current-carrying terminal and the gate of the transistor which is operable during the application of a drive signal so as to store a gate voltage on the capacitance determined by the drive signal.
Dependencies are inferred from the claim text.