Active matrix display devices and methods of driving such

An active matrix display device comprising sets of row and column address conductors, a row and column array of electro-optic display elements operable to produce a display, each of which is connected in series with a two terminal non-linear switching device between a row conductor and a column conductor, and a drive circuit connected to the sets of row and column address conductors for applying selection signals to the row address conductors to select the rows of display elements and data signals to the column address conductors to drive the selected display elements to produce a required display effect, wherein the data signals comprise pulse width modulated signals whose width determines a desired grey scale output from a display element, and wherein the drive circuit is adapted to provide selection signals which comprise voltage pulse signals whose magnitude increases to a maximum voltage amplitude such that the current flowing through a non-linear switching device during the application of a selection signal tends towards a substantially constant value.