Patent ID: 7944410

Claim:
A controlled current display driver for a passive matrix organic light emitting diode (OLED) display, said display having a matrix of OLED pixels addressed by row and column electrodes, said display driver being configured to simultaneously drive a plurality of said column electrodes with a plurality of column currents and a plurality of said row electrodes with a plurality of row currents such that a sum of said column currents is divided between said row electrodes in a variable ratio, the display driver comprising: a plurality of column current sources for driving said column electrodes simultaneously with a plurality of controlled column currents; and a current generator, the current generator comprising: a first, reference current input to receive a reference current for driving a first of said plurality of row electrodes; a second, ratioed current input to receive a ratioed current for driving a second of said plurality of row electrodes; a first ratio control input to receive a first row current ratio control; a controllable current mirror having a first current generator control input coupled to said first ratio control input, a current input coupled to said reference current input, and an output coupled to said ratioed current input; said current generator being configured such that a signal on said first current generator control input controls a ratio of said ratioed current to said reference current; such that said sum of said column currents is divided in proportion to said ratio of said ratioed current to said reference current.