Passive matrix display drivers

A method of driving a passive matrix electroluminescent display, the display having a plurality of rows and columns of emissive elements addressed by respective row and column electrodes, the method comprising:

• addressing said row electrodes, one at a time;
• driving a set of said column electrodes while addressing each said row electrode;
• converting drive level data for a set of said emissive elements into first data defining column drive current signal ratios of a drive current for a particular column electrode to an overall column drive current for said set of said column electrodes and second data defining an overall row drive current,
• wherein said column electrode driving comprises driving said set of said column electrodes at said column drive current signal ratios for said set of column electrodes;
• and
• driving each said addressed row at said overall row drive current to control a drive current to said emissive elements in each said addressed row,
• wherein said driving comprises driving said column electrodes with a current driver comprising a current mirror having a reference input and a plurality of outputs, and wherein said outputs are coupled to said column electrodes and one of said column electrodes is coupled to said reference input of said current mirror.