In most EPD application scenarios, such as electronic retail shelf labelling, a conventional global update will prove to be sufficient. Here every pixel on the EPD is refreshed, as there are no time pressures and this can be done when the EPD is not being viewed by anyone (such as when the store is closed).
There are, however, certain applications that require rendered information to be refreshed at a quicker rate, while still being viewed.
Using partial updates, rather than refreshing every pixel, the rendered information in a smaller section of the EPD can be refreshed. Changes can be implemented within a shorter time frame and there is even potential for simple animations to be displayed. Until now, the drawback of this has been that partial updates can often result in ghosting, where traces of the previous image remain present on the new image. This impacts on image quality and is clearly detrimental to the user experience. It may also reduce the EPD’s working lifespan.
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