Methods for driving electro-optic displays

Abstract

There are provided display controllers and driving methods related to those described in US Published Patent Application No. 2013/0194250. These include (a) a display controller having an update buffer, means for removing from the update buffer pixels not requiring updating, and means to ensure that pixels having certain special states are not removed from the update buffer; (b) a method of driving a bistable display wherein, in a pixel undergoing a white-to-white transition and lying adjacent another pixel undergoing a visible transition, there is applied to the pixel one or more balanced pulse pairs and at least one top-off pulse; (c) a method of driving a bistable display by overlaying a non-rectangular item over a pre-existing image content and then removing the item, where only pixels in the region of the item perform transitions (including self-transitions); and (d) a method of driving a bistable display in which a proportion of background pixels not undergoing an optical change are subjected to a refresh pulse to correct optical state drift.

1 . A display controller capable of controlling the operation of a bistable electro-optic display and having an update buffer, means for removing from the update buffer pixels which do not require updating during a given transition, means for receiving a list of states that should not be removed from the update buffer, and means to ensure that pixels having listed states are not removed from the update buffer. 
     
     
         2 . A display controller capable of controlling the operation of a bistable electro-optic display and having an update buffer, and means for removing from the update buffer pixels which do not require updating during a given transition, the controller having at least one special transition having two states associated therewith, means to determine when a pixel is undergoing a special transition immediately after a previous special transition, and means to insert into the update buffer the second state associated with the at least one special transition when a pixel is undergoing a special transition immediately after a previous special transition. 
     
     
         3 . A display controller according to  claim 1  wherein the specified drive method is applied only to pixels within one or more defined regions of the display and a different drive scheme is applied to pixels outside the defined region or regions. 
     
     
         4 . A bistable electro-optic display comprising a drive controller according to  claim 1 . 
     
     
         5 . An electro-optic display according to  claim 4  comprising a rotating bichromal member, electrochromic or electro-wetting material. 
     
     
         6 . An electro-optic display according to  claim 4  comprising an electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field. 
     
     
         7 . An electro-optic display according to  claim 6  wherein the electrically charged particles and the fluid are confined within a plurality of capsules or microcells. 
     
     
         8 . An electro-optic display according to  claim 6  wherein the electrically charged particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material. 
     
     
         9 . An electro-optic display according to  claim 6  wherein the fluid is gaseous. 
     
     
         10 . An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label, variable transmission window or flash drive comprising a display according to  claim 4 . 
     
     
         11 . A method of driving a bistable electro-optic display comprising overlaying a non-rectangular item over pre-existing text or image content followed by removal of the item, wherein only pixels in the region of the item perform transitions (including self-transitions). 
     
     
         12 . A method according to  claim 11  wherein the item includes at least one transparent region, and wherein only pixels in the non-transparent regions of the item perform transitions (including self-transitions). 
     
     
         13 . A display controller or electro-optic display arranged to carry out the method of  claim 11 .