Electrophoretic Display Driving Method for Temperature-Compensated DC Balance
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Solution Overview
Problem
Electrophoretic display devices face challenges in maintaining long-term reliability due to non-zero average electric fields and increased refresh times, especially when temperature changes affect the viscosity of the dispersion solution, leading to deviations in electric field direction and magnitude, and prolonged reset and drive pulse durations.
Innovation Solution
A method for driving electrophoretic display devices using a partial drive format that allows for shorter refresh times and compensates for temperature changes by adjusting drive pulse signals based on temperature changes, ensuring a DC balance and reducing afterimages through temperature detection and adjusted pulse signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the durations of reset pulse and drive pulse are established on the basis of scaling functions which are each independent, then the image quality is improved by compensating for temperature changes, but the DC balance cannot be ensured and long-term reliability deteriorates
Solution Approach 1:
The patent adjusts the duration of reset pulse and drive pulse based on temperature changes using a unified scaling function. The control unit receives temperature information and modifies pulse durations dynamically to maintain both image quality and DC balance. This parameter change approach allows the system to adapt to temperature variations while ensuring the time average of electric field remains substantially zero, thus maintaining long-term reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit receives temperature information from temperature information acquisition means and adjusts the pulse durations accordingly. This closed-loop control ensures that both image quality and DC balance are maintained by continuously adapting the driving parameters based on actual temperature conditions.
2Reliability
If the durations of reset pulse and drive pulse are aligned to the longer duration, then DC balance is ensured, but the refresh time for image is remarkably delayed
Solution Approach 1:
The patent employs dynamic adjustment of pulse durations based on temperature conditions rather than using fixed aligned durations. The control unit calculates optimal reset pulse and drive pulse durations using a unified scaling function that considers temperature, allowing the system to maintain DC balance with shorter overall refresh times when conditions permit, thus improving productivity while ensuring reliability.
Solution Approach 2:
By changing the pulse duration parameters dynamically based on temperature and display conditions, the system can achieve DC balance without always using the longer aligned duration. This parameter optimization allows shorter refresh times while maintaining the necessary electric field balance for long-term reliability.
3Temperature
If temperature changes occur, then the viscosity of dispersion solution changes causing deviation in electric field direction and magnitude, but the display image appears differently
Solution Approach 1:
The patent adjusts the duration of reset pulse and drive pulse based on temperature changes to compensate for viscosity variations in the dispersion solution. By modifying these parameters dynamically, the system counteracts the effects of temperature-induced viscosity changes, maintaining consistent electric field application and ensuring display image consistency across different temperature conditions.
Solution Approach 2:
The system takes preliminary action by adjusting the pulse durations before temperature changes can significantly affect the display. The control unit proactively modifies the driving parameters based on detected temperature variations, preventing display inconsistencies before they occur by compensating for the anticipated viscosity changes in the dispersion solution.
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
The method enhances long-term reliability and display quality by shortening refresh times and maintaining a DC balance, even with temperature changes, while preventing afterimages from forming, thus improving the overall performance of electrophoretic display devices.
Implementation Method 1
An electrophoretic display device displays an image by using an applied electric field to move, for example, white and black charged electrophoretic particles. The charged particles move through a dispersion solution
Implementation Method 2
a temperature detection unit configured to measure a temperature of the display unit
Implementation Method 3
a voltage based on a drive pulse signal repeating a first electric potential and a second electric potential is applied to the common electrode and a voltage based on a normal signal or an inverse signal of the drive pulse signal is applied to each of the plurality of pixel electrodes, thereby causing the electrophoretic particles to be moved by an electric field produced between the pixel electrodes and the common electrode
Data Source
AI summary
A method includes: causing a first image to be displayed in a first color by a partial drive format; causing a background of the first image to be displayed in the first color; causing a background of a second image to be displayed in a second color; and causing the second image to be displayed in the second color. In a case where a temperature detection unit detects a predetermined change in temperature after causing a background of a second image to be displayed in a second color and before causing the second image to be displayed in the second color, then causing a predetermined image to be displayed and causing the predetermined image to be complementarily displayed using a drive pulse signal adjusted for the temperature after the change.