Patent ID: 8922544

Claim:
A display system comprising: a pixel circuit including a light emitting device and a driving transistor for driving current through the light emitting device according to a driving voltage across the driving transistor, the pixel circuit further including one or more switch transistors arranged to selectively connect the pixel circuit to a signal line and a monitoring line; a driver for programming the pixel circuit with the driving voltage via the signal line; a monitor for measuring a current through the driving transistor via the monitoring line; and a controller for operating the driver and the monitor, the controller being configured to: measure a first current through the drive transistor, via the monitor, for a duration sufficient for the current on the monitoring line to settle at a steady value and thereby avoid propagation delay effects of the monitoring line; measure a second current through the drive transistor, via the monitor, for a duration provided for a monitoring timing budget of the display; and compare the measured first and second currents to extract the propagation delay effects of the monitoring line for the pixel.