Electro-optic displays, and methods for driving same

Abstract

The invention relates to electro-optic displays and methods for driving such displays. The invention provides (i) electrochromic displays with solid charge transport layers; (ii) apparatus and methods for improving the contrast and reducing the cost of electrochromic displays; (iii) apparatus and methods for sealing electrochromic displays from the outside environment and preventing ingress of contaminants into such a display; and (iv) methods for adjusting the driving of electro-optic displays to allow for environmental and operating parameters.

1 . An electro-optic display comprising:
 an electro-optic medium;   at least one electrode arranged to apply an electric field to the electro-optic medium;   drive means for supplying a driving pulse to the electrode;   a sensor for measuring at least one parameter affecting the behavior of the electro-optic medium and for producing an output signal representative of the parameter; and   control means for receiving the output signal from the sensor and controlling the drive means to vary the driving pulse dependent upon the output signal,   wherein said sensor comprises at least one of:   (a) a temperature sensor for sensing the temperature of, or adjacent to, the electro-optic medium;   (b) a humidity sensor for sensing the humidity of, or adjacent to, the electro-optic medium; and   (c) a timer for measuring the operating time of the electro-optic medium.   
     
     
         2 . An electro-optic display according to  claim 1  wherein said sensor comprises a temperature sensor for sensing the temperature of, or adjacent to, the electro-optic medium. 
     
     
         3 . An electro-optic display according to  claim 1  wherein said sensor comprises a humidity sensor for sensing the humidity of, or adjacent to, the electro-optic medium. 
     
     
         4 . An electro-optic display according to  claim 1  wherein said sensor comprises a timer for measuring the operating time of the electro-optic medium. 
     
     
         5 . An electro-optic display according to  claim 1  having a plurality of electrodes arranged to apply an electric field to a plurality of pixels of the electro-optic medium, and wherein the drive means is arranged to vary the driving pulse to one electrode based upon the driving pulse applied to at least one other electrode. 
     
     
         6 . An electro-optic display according to  claim 1  wherein the electro-optic medium is an electrophoretic medium comprising a suspending fluid, and a plurality of electrically charged particles suspended in the suspending fluid and capable of moving therethrough on application of an electric field to the suspending fluid. 
     
     
         7 . An electro-optic display according to  claim 6  wherein the suspending fluid and the plurality of electrically charged particles are retained within a plurality of capsules. 
     
     
         8 . An electro-optic display according to  claim 6  wherein the suspending fluid and the plurality of electrically charged particles are present as a plurality of discrete droplets and a continuous phase of polymeric material surrounds the droplets. 
     
     
         9 . An electro-optic display according to  claim 6  wherein the suspending fluid and the plurality of electrically charged particles are retained within a plurality of cavities formed in a carrier medium. 
     
     
         10 . An electro-optic display according to  claim 1  wherein the electro-optic medium is a rotating bichromal member medium or an electrochromic medium. 
     
     
         11 . An electrochromic display comprising an electrolyte and an electrochromically-active layer comprising a nano-porous-nano-crystalline film comprising a semiconducting metal oxide having an electroactive compound which is either a p-type or n-type redox promoter or p-type or n-type redox chromophore adsorbed thereon or otherwise attached thereto, the electrolyte having a light scattering and/or reflective material dispersed therein. 
     
     
         12 . An electrochromic display comprising a nano-porous-nano-crystalline film comprising a semiconducting metal oxide having an electroactive compound which is either a p-type or n-type redox promoter or p-type or n-type redox chromophore adsorbed thereon or otherwise attached thereto, the display having a viewing surface through which an observer can view the display, the display also having, on the opposed side of the film from the viewing surface, a layer of a light-scattering or reflective material disposed on the film. 
     
     
         13 . An electrochromic display comprising an electrochromically-active layer comprising a nano-porous-nano-crystalline film comprising a semiconducting metal oxide having an electroactive compound which is either a p-type or n-type redox promoter or p-type or n-type redox chromophore adsorbed thereon or otherwise attached thereto, the film being formed from a semiconducting metal oxide coated with at least one of silica and alumina. 
     
     
         14 . A process for forming an electrochromic display according to  claim 13 , the process comprising:
 coating particles of a semiconducting metal oxide with at least one of silica and alumina; and   forming the coated particles into the film at a temperature not greater than about 400 C.