Electrophoretic Display Driving Method Using AC Waveforms
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Solution Overview
Problem
Conventional electrophoretic display devices require high drive voltages, leading to increased storage capacity needs, larger and more costly data drive integrated circuits due to 2-bit digital data per cell and high voltage elements.
Innovation Solution
An electrophoretic display device and driving method that utilize AC common and data waveforms to reduce drive voltage, with initializing and entry voltages generated based on current and next frame data, applying AC waveforms for initialization and data entry, reducing the need for high voltage elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high data voltages (+15V and -15V) are used to drive electrophoretic display cells, then gray scale expression is achieved, but the drive voltage becomes high requiring high voltage elements in D-IC
Solution Approach 1:
The patent applies periodic AC waveforms instead of static DC voltages. The common electrode receives AC common waveforms that alternate in polarity, enabling gray scale control through pulse width modulation while keeping the magnitude of voltages lower. This periodic action allows the display to achieve gray scale expression without requiring high voltage elements.
Solution Approach 2:
The patent changes the control parameter from voltage magnitude to pulse width (duty cycle). By varying the width of AC voltage pulses applied to the data electrode while maintaining lower voltage magnitudes, the system achieves gray scale expression. This parameter change eliminates the need for high voltage elements in the data drive integrated circuit.
2Manufacturing precision
If 2-bit digital data is used per cell for gray scale control, then gray scale expression is achieved, but the storage capacity of memory increases
Solution Approach 1:
The patent changes the control parameter from voltage magnitude to pulse width (duty cycle). By varying the width of AC voltage pulses applied to the data electrode while maintaining lower voltage magnitudes, the system achieves gray scale expression. This parameter change eliminates the need for high voltage elements in the data drive integrated circuit.
3Reliability
If high voltage elements are used in data drive integrated circuit to handle +15V and -15V data voltages, then the circuit can drive the display, but the size of D-IC increases
Solution Approach 1:
The patent changes the control parameter from voltage magnitude to pulse width (duty cycle). By varying the width of AC voltage pulses applied to the data electrode while maintaining lower voltage magnitudes, the system achieves gray scale expression. This parameter change eliminates the need for high voltage elements in the data drive integrated circuit.
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 solution decreases the drive voltage, reducing the size and cost of data drive integrated circuits while maintaining effective gray scale expression through pulse width modulation of the drive waveform.
Implementation Method 1
If a material having an electric charge is placed in DC electric field, the material moves in accordance with electric charges, the size and shape of molecules and the like. Such a movement, i.e., a phenomenon in which materials are separated by the difference of movement, is named 'Electrophoresis.'
Data Source
AI summary
A method of driving at least one cell of an electrophoretic display panel through a pixel electrode and a common electrode includes storing at least first data representative of an image currently displayed and second data representative of an image to be displayed; and applying a first AC data waveform and a first AC common waveform for initializing the at least one cell during a first number of frames, applying a second AC data waveform and a second AC common waveform for displaying the second data during a second number of frames, wherein the first number of frames depends on the first data and the second number of frames depends on the second data.