Research On Driving Mechanism Of Paper-like Display For High Response And High Luminance Pixels

Paper-like displays have the advantages of readability in bright light and low power consumption.They are widely used in e-books,billboards and portable devices.The traditional paper-like display is electrophoretic display(EPD).In order to achieve a rich color display,three-color EPDs can be prepared by adding red particles into EPD microcapsules.But the performance of three-color EPDs is reduced by defects such as long response time,ghost image and flickers.In this thesis,the defects were effectively suppressed by exploring and optimizing driving schemes.However,it is difficult to realize video playback and full color display on three-color EPDs.In order to improve the performance of paper-like displays,electrowetting displays(EWDs)were further studied.High luminance and short response time can be achieved by inhibiting oil splitting,charge trapping and oil backflow.The main research contents are as follows.1)In view of long response time of three-color EPDs,a motion characteristic of particles was analyzed by electrophoretic theory,and the relationship between response time and spatial position of particles was clarified.A new driving scheme was proposed to reduce response time.The effects of amplitude and frequency on particle activity were elucidated,then,an activation stage was redesigned to reduce the distance between black and white particles and a common electrode plate.Compared with a traditional driving scheme,the response time of black particles was reduced by 45% and the response time of white particles was reduced by 40%.Moreover,the maximum flicker intensity and flickers were significantly suppressed.2)In view of ghost image and flickers of three-color EPDs,a driving scheme based on high frequency voltage was proposed.A high frequency voltage was used to activate particles and unify a grayscale.Then,a separation stage was added to reduce the mixing of red and black particles.The results showed that flickers could be suppressed when pixels were driven to black,reduced by 88.9% when pixels were driven to white,and reduced by 90% when pixels were driven to red.The response time of black and white particles was reduced to 1.32 s and the response time of red particles was reduced to2.97 s.3)Compared with three-color EPDs,the response time of EWDs is extremely short.However,display performance of EWDs is reduced by oil splitting,charge trapping and oil backflow.In order to suppress these defects,a driving scheme based on an exponential function and alternating current(AC)voltage was proposed.The slope of driving voltage could be adjusted by controlling a power constant,thus avoiding oil splitting.Then,the influence of AC voltages on oil stability was studied.Trapped charges were released by negative voltages,which inhibited oil backflow.Compared with a traditional driving scheme,the response time was reduced by 27.3% and luminance value was increased by 16.2%.The causes and effects of different defects were studied and analyzed in this thesis.New driving schemes were designed to solve these defects.The research results showed that the response time and luminance value were effectively improved,which provided some reference value for the industrialization application of paper-like displays.