Abstract: Display driver circuits are described for driving organic light emitting diode displays, particularly passive matrix displays, with greater efficiency. The display drivers comprise a controllable current generator to provide a variable current drive output to an OLED display, the current generator comprising at least one bipolar transistor in series with the current drive output. The display brightness is adjustable by controlling the current generator to vary the current drive to the display. Preferably the bipolar transistor has an emitter terminal substantially directly connected to a power supply line of the driver to reduce losses in the driver. A corresponding method is also described. By employing a bipolar transistor current drive and varying display brightness by controlling the current an efficient driver-display combination is obtained.

Abstract: 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 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 the photosensitive device, a first control device coupled between the photosensitive device and a data line and responsive to a first control signal on a first control line to couple the photosensitive device to the data line, and a second control device coupled between the photosensitive device and the driver and responsive to a second control signal on a second control line to couple the photosensitive device to the driver. The circuit can be operated in a number of different modes and provides flexible control of an electro-display element such as an organic LED pixel.

Abstract: 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.