Display driver circuitry for electro-optic displays, in particular active
matrix displays using organic light emitting diodes. The circuitry
includes a driver to drive an electro-optic display element in accordance
with a drive voltage, a photosensitive device optically coupled to the
electro-optic display element to pass a current dependent upon
illumination reaching photosensitive device, a control circuit having a
control line coupled to the driver to control the brightness of the
electro-optic display element and having a current sense input coupled to
the photosensitive device, a current set line for coupling to a reference
current generator, and a display element select line to, when active,
cause the control circuit to drive the electro-optic display element in
accordance with the current set by the reference current generator. The
circuit provides improved control of an electro-display element such as
an organic LED pixel.