Methods and systems for managing remnant voltage during fast updates in electrophoretic displays
AssigneeE Ink Corporation
InventorsSanket DIWALE, Amit DELIWALA
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Abstract
Methods for actively managing remnant voltage on backplane electrodes when driving an electrophoretic display, especially with short waveforms, such as used for scrolling, pinch-zoom, pulldown menus, and even video. The methods track the remnant voltage changes for each backplane electrode during a series of image updates and use same color transitions to either improve the optical quality state of the display pixel or to decrease the remnant voltage at the display pixel. Thus, it is not necessary to employ full reset pulses, which typically drive a backplane electrode to both extreme voltage states and appear very “flashy” to a user.
Claims22
A method for regulating remnant voltage in an electrophoretic display comprising a layer of electrophoretic media disposed between a light-transmissive electrode and a plurality of drive electrodes and a controller coupled to the plurality of drive electrodes, the method comprising:
- determining for each display pixel in the electrophoretic display whether that display pixel has a same color state for a first image and a second image;
- sending instructions to the controller to provide waveforms corresponding to a transition from the color state of the first image to the color state of the second image for each display pixel that does not have the same color state for the first image and the second image;
- determining a calculated remnant voltage for each display pixel having the same color state for the first image and the second image;
- determining a projected remnant voltage for each display pixel having the same color state for the first image and the second image when that display pixel receives instructions to increase optical quality state;
- comparing the projected remnant voltage for each display pixel having the same color state for the first image and the second image to a remnant voltage threshold;
- sending instructions to the controller to provide waveforms causing an increase in optical quality state for each display pixel having the same color state for the first image and the second image and having a projected remnant voltage less than the remnant voltage threshold;
- and
- sending instructions to the controller to provide waveforms causing a decrease in remnant voltage for each display pixel having the same color state for the first image and the second image and having a projected remnant voltage greater than or equal to the remnant voltage threshold.
An electrophoretic display configured to actively manage remnant voltage during updates, comprising:
- a light-transmissive electrode;
- a plurality of drive electrodes;
- a layer of electrophoretic media disposed between the light-transmissive electrode and the plurality of drive electrodes;
- a controller coupled to the plurality of drive electrodes;
- and
- a processor, the processor configured to:
- determine for each display pixel in the electrophoretic display whether that display pixel has a same color state for a first image and a second image,
- send instructions to the controller to provide waveforms corresponding to a transition from the color state of the first image to the color state of the second image for each display pixel that does not have the same color state for the first image and the second image,
- determine a calculated remnant voltage for each display pixel having the same color state for the first image and the second image,
- determine a projected remnant voltage for each display pixel having the same color state for the first image and the second image when that display pixel receives instructions to increase optical quality state,
- compare the projected remnant voltage for each display pixel having the same color state for the first image and the second image to a remnant voltage threshold,
- send instructions to the controller to provide waveforms causing an increase in optical quality state for each display pixel having the same color state for the first image and the second image and having a projected remnant voltage less than the remnant voltage threshold, and
- send instructions to the controller to provide waveforms causing a decrease in remnant voltage for each display pixel having the same color state for the first image and the second image and having a projected remnant voltage greater than or equal to the remnant voltage threshold.
Dependencies are inferred from the claim text.