Electrowetting Display Pixel Voltage Polarity Inversion
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Solution Overview
Problem
Existing electrowetting display devices suffer from unsatisfactory image display due to inability to maintain display state at longer periods, especially at low frame rates, and exhibit differences in display states when driven with positive and negative pixel voltages of the same magnitude.
Innovation Solution
The method involves applying a first pixel voltage during a sub-frame, followed by a second pixel voltage with different polarity, and maintaining the pixel state using a TFT, while inverting the polarity of the pixel voltage during the display period to compensate for polarity-dependent fluid configurations and storage capacitor connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a constant pixel voltage is applied during the display period, then the display state is maintained during short periods, but the display state cannot be maintained at longer display periods especially at low frame rates
Solution Approach 1:
The patent applies periodic action by inverting the pixel voltage polarity at specific moments during the display period. Instead of maintaining a constant voltage, the system periodically switches between positive and negative voltage polarities to refresh and maintain the display state throughout the entire display period, enabling reliable operation at low frame rates.
Solution Approach 2:
The patent uses inversion by applying voltage polarity inversion during the display period. The pixel voltage is inverted from positive to negative or vice versa at predetermined moments, which compensates for fluid configuration differences and maintains the display state throughout long display periods, solving the problem of state degradation at low frame rates.
2Manufacturing precision
If the same magnitude of pixel voltage is applied with different polarities, then the voltage magnitude is consistent, but the display states differ due to polarity-dependent fluid configurations
Solution Approach 1:
The patent explicitly addresses polarity-dependent display state differences by inverting the voltage polarity during the display period. This inversion compensates for the asymmetric response of the electroconductive fluid to positive and negative voltages, ensuring that display states remain consistent despite using the same voltage magnitude with different polarities.
Solution Approach 2:
The patent changes the voltage polarity parameter during the display period to compensate for fluid configuration differences. By switching between positive and negative polarities, the system adjusts the electrical parameter to maintain consistent display states despite the inherent asymmetry in fluid response to different voltage polarities.
3Reliability
If the polarity of pixel voltage is inverted during display period, then display state maintenance is improved, but the voltage conversion complexity increases
Solution Approach 1:
The patent implements voltage polarity inversion during the display period to maintain display states at low frame rates. The conversion system uses different conversion formulas for positive and negative voltages, selecting the appropriate formula based on the current polarity to achieve reliable display state maintenance while managing conversion complexity.
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 effectively maintains the display state during long display periods, improving image quality by inverting pixel voltage polarity and using different voltage conversions for positive and negative voltages, suitable for low-frequency driving of electrowetting display devices.
Implementation Method 1
A known electrowetting display device has a plurality of picture elements or pixels... The position of the first fluid in the pixel is controlled by the applied voltage and causes a display effect
Implementation Method 2
The pixel comprises a storage capacitor directly connected between the first electrode and the second electrode
Data Source
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AI summary
A method of driving an electrowetting display device including at least one pixel, the method comprising: applying a first pixel voltage to the pixel during a first portion of the display period; and applying a second pixel voltage to the pixel during a second portion of the display period, the first and second pixel voltages corresponding to a display state of the pixel, and the first pixel voltage and the second pixel voltage having different polarities.