Patent ID: 7453435

Claim:
A method of controlling the grey state of pixels in an electrochromic matrix display comprising a first set of electrodes formed of electrically isolated conduction lines, a second set of electrodes formed of electrically isolated conduction lines, an electrochromic material arranged between or on said first and second sets of electrodes and a drive arranged to supply drive voltages selectively to individual electrodes in said first and second sets of electrodes, said first and second sets of electrodes being arranged in a pattern such that each electrode in said first set intersects each electrode in said second set at a single intersection and each electrode in said second set intersects each electrode in said first set at a single intersection, said intersections between the first and second sets of electrodes forming a set of pixels, wherein said method comprises the steps of: providing select or unselect signals from said drive to one of said sets of electrodes, said electrodes forming select lines, wherein the select or unselect signals, which are independent of the desired image pattern, are applied on the select lines to select and unselect groups of pixels along their respective select line; providing data signals from said drive to the other set of electrodes, said electrodes forming data lines, wherein the data signals, which are applied on the data lines to affect greyscale states of selected pixels, are dependent on the desired image pattern; wherein the electric signal for a particular greyscale state on a particular data line is a function of the distribution of the greyscale states of the pixels along said particular data line; wherein one of two constant voltages U DARK and U LIGHT are applied on a particular data line, wherein U DARK is applied if the greyscale state of the selected pixel along the data line belongs to one group of greyscale states and U LIGHT is applied if the greyscale state of the selected pixel along the data line belongs to another group of greyscale states; wherein only two possible greyscale states of the pixels exist; wherein U DARK is a monotonic function of the number of desired dark pixels along the data line and U LIGHT is a constant.