Electro-optical Device Driving Method for High-Speed Partial Rewriting
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Solution Overview
Problem
Existing electro-optical devices, such as electronic paper terminals with electrophoretic display devices, face challenges in achieving high-speed display switching, particularly for partial image rewriting like handwriting input, where the current methods require similar time for full and partial image updates, leading to inefficiencies in display state transitions.
Innovation Solution
A method for driving electro-optical devices that involves applying specific voltages to first and second electrodes to select different display states for pixels, allowing for high-speed image rewriting by varying the voltage based on the size of the rewritten region and the number of connected scanning lines, enabling faster partial display updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a periodic rectangular wave is supplied to the common electrode to increase contrast, then display quality is ensured, but the time required for image rewriting increases to 1-2 seconds
Solution Approach 1:
The patent applies different voltage strategies to different regions of the display based on whether they are being rewritten or maintained. For rewritten pixels, a first voltage is applied to the common electrode, while for non-rewritten pixels, a second voltage (rectangular wave) is applied to maintain contrast. This local differentiation allows contrast enhancement only where needed, reducing overall rewriting time while maintaining display quality.
Solution Approach 2:
The patent dynamically adjusts the voltage applied to the common electrode based on the rewriting status of pixels. The voltage switching timing is synchronized with the image signal input timing, creating a dynamic control scheme that adapts to the specific rewriting requirements of each pixel region, thereby optimizing both speed and quality.
2Reliability
If the same contrast enhancement process is applied to all pixels, then display quality is maintained, but partial rewriting speed is reduced to be similar to entire rewriting speed
Solution Approach 1:
The patent implements local quality control by applying contrast enhancement (rectangular wave voltage) only to pixels that are not being rewritten, while allowing rewritten pixels to use a different voltage scheme. This selective application of contrast enhancement enables partial rewriting to proceed at high speed without compromising the display quality of non-rewritten regions.
Solution Approach 2:
The patent segments the pixel array into rewritten and non-rewritten regions, applying different voltage control strategies to each segment. This segmentation allows the system to optimize for speed in rewritten regions while maintaining quality in non-rewritten regions, thereby achieving high-speed partial rewriting capability.
3Speed
If a higher voltage is applied to the electro-optical material layer for partial rewriting, then display state transition speed increases, but power consumption increases
Solution Approach 1:
The patent applies higher voltage only to the common electrode during specific timing periods for rewritten pixels, rather than continuously or to all pixels. This localized and time-limited high voltage application achieves fast display state transition in rewritten regions while minimizing overall power consumption compared to applying high voltage universally or continuously.
Solution Approach 2:
The patent uses periodic voltage application to the common electrode, switching between first voltage (for rewritten pixels) and second voltage (for non-rewritten pixels) in sync with the image signal input. This periodic action enables high-speed transitions when needed while reducing average power consumption by not maintaining high voltage continuously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for high-speed image rewriting by increasing the voltage applied to the electro-optical material layer, reducing the time required for partial updates and maintaining desired contrast, even with low responsiveness materials, thereby enhancing usability and display quality.
Implementation Method 1
electronic paper terminals using electrophoretic display devices
Data Source
AI summary
A method of driving an electro-optical device including a plurality of pixels, one of which having a first electrode, a second electrode, and an electro-optical material layer, includes: when an image is rewritten, selecting a first display state of the one pixel by applying a first voltage to the first electrode and applying a second voltage to the second electrode, or selecting a second display state of the one pixel by applying a third voltage to the second electrode; and when a part of the image is rewritten, selecting any of the first display state and the second display state of the one pixel by applying a fourth voltage which is different from the first voltage to the first electrode and applying a fifth voltage which has a different polarity from that of the fourth voltage with respect to the first voltage to the second electrode.