Electrophoretic Display Refresh Control for Afterimage Reduction
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Solution Overview
Problem
The refresh process in electrophoretic displays (EPDs) is burdensome for users as it resets the entire screen, causing discomfort and reducing usability, as existing methods do not effectively mitigate the visual impact of the refresh process.
Innovation Solution
A display device with a controller that performs a refresh process on target pixels distributed at wider intervals than regular intervals, using pseudo random numbers to select pixels for refresh, and inverting binary information values, while focusing more frequent refreshes on areas with significant signal value differences to reduce visual impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh process is performed on the entire screen, then afterimages are eliminated, but user comfort deteriorates and usability is reduced
Solution Approach 1:
The patent segments the screen into multiple pixel groups and performs refresh processes on different groups in different cycles. Instead of refreshing all pixels simultaneously, the controller divides pixels into first and second groups, refreshing the first group in odd cycles and the second group in even cycles. This segmentation distributes the visual impact of refresh operations over time, eliminating afterimages while maintaining user comfort.
Solution Approach 2:
The patent implements periodic refresh actions with alternating patterns. The controller performs refresh processes periodically on different pixel groups based on cycle parity (odd/even cycles). This periodic action ensures that afterimages are systematically eliminated while the alternating pattern prevents concentrated visual disruption, thereby maintaining user comfort during normal display operation.
2Reliability
If refresh process is performed frequently, then afterimage elimination is improved, but power consumption increases
Solution Approach 1:
By segmenting pixels into multiple groups and refreshing them alternately, the patent reduces the frequency of refresh operations on any single pixel group. Each group is refreshed less frequently than if all pixels were refreshed in every cycle, thereby reducing overall power consumption while maintaining effective afterimage elimination through the alternating pattern.
Solution Approach 2:
The periodic alternating refresh pattern allows the display to maintain afterimage elimination effectiveness while reducing the average refresh frequency. By switching between different pixel groups in odd and even cycles, the system achieves reliable afterimage prevention with lower cumulative power consumption compared to refreshing all pixels in every cycle.
Data Source
AI summary
A display device includes: a display medium having a screen area in which pixels are disposed at regular intervals; and a controller that causes the display medium to display an image. The controller is configured to perform refresh process on target pixels that are included in a different pixel pattern for each predetermined refresh cycle. The target pixels being of the pixels disposed in the screen area and being distributed at intervals wider than the regular intervals.