Patent ID: 7474288
Filing Date: 2009-01-06
Classification: G09G

Abstract:
1. Display driver control circuitry for a passive matrix emissive display, the display comprising a plurality of pixels arranged in rows and columns and addressed by row and column electrodes, the control circuitry being configured to address each row in turn to give the appearance of an image on the display, the control circuitry further comprising: a frame memory interface for reading data from a frame memory for presentation on the display; a blank line identifier for identifying one or more substantially blank rows of pixels defined by said data; wherein the control circuitry is further configured to skip past said one or more blank rows of pixels during said row addressing without addressing of the blank rows; a set of column drivers each including a column drive controllable current generator, each said column drive controllable current generator having a first power supply input to receive a power supply from said display driver control circuitry and a second current control input and having a column drive output to provide a column drive to said display; wherein said set of column drivers further comprises at least one digital-to-analogue converter having a digital input to receive a pixel brightness control signal and having an analogue output coupled to a said second current control input of said column drive controllable current generator; and a reference current or voltage generator to set a reference current or voltage for said set of column drive controllable current generators, said reference current or voltage generator having a power supply input to receive power from said power supply and a reference current or voltage control input to control said reference current or voltage; and wherein said display driver control circuitry further comprises a reference drive signal line coupled to said reference current or voltage control input to provide a reference control signal for scaling a set of column drives from said set of column drive controllable current generators; and wherein said reference control signal is configured to control said reference current or voltage generator in proportion to the number of identified blank rows of pixels such that a perceived pixel brightness remains substantially constant as the number of identified blank rows of pixels varies.