Patent ID: 8780142
Filing Date: 2014-07-15
Classification: G09G

Abstract:
1. An active matrix liquid crystal display device comprising: an array of pixels arranged in rows and columns, each pixel comprising a liquid crystal cell; a column driver circuit for providing pixel drive signals to the columns of pixels, wherein the column driver circuit comprises an array of current source circuits, a respective current source circuit being provided for each column of pixels, wherein each current source circuit comprises: a current source; and a supply switch for controlling the time during which the current source supplies current to or drains current from the column, and wherein the device further comprises a mapping means for deriving a digital value from the transmittance of the liquid crystal cell, wherein the digital value represents a time period for the control of the supply switch of each current source circuit, the mapping means implementing a single mapping function for use in providing the digital values for all current source circuits; wherein the column driver circuit is adapted to apply a polarity inversion scheme such that the current source is controlled to supply current to or drain current from the column thereby generating a voltage corresponding to a positive gamma curve and a voltage corresponding to a negative gamma curve on a capacitor of the liquid crystal cell alternately.