Electrophoretic Display Driving Signal Balancing Vertical Gravity
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Solution Overview
Problem
Electro-phoretic displays in vertical orientation experience display quality issues due to gravitational effects on particle distribution, leading to a yellowish appearance of black frames caused by the sinking of yellow electro-phoretic particles during the driving process.
Innovation Solution
A driving method for electro-phoretic displays that utilizes a driving signal with a first pulse of larger width before the driving stage and a second pulse in the resetting stage, ensuring effective movement and distribution of electro-phoretic particles to improve display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the electro-phoretic display is driven in vertical orientation, then the display can be compact and space-efficient, but gravitational effects cause yellow electro-phoretic particles to sink and accumulate at the display end, resulting in yellowish black frames and degraded display quality
Solution Approach 1:
The patent applies a preliminary balancing pulse before the main driving pulse to counteract gravitational effects on electro-phoretic particles. This preliminary action redistributes particles uniformly throughout the liquid crystal layer, preventing yellow particle accumulation at the display end during vertical operation, thereby maintaining display quality while preserving compact vertical orientation
Solution Approach 2:
The patent modifies the driving signal parameters by introducing a dual-pulse waveform with different amplitudes and durations. The first pulse has higher amplitude and longer duration to overcome gravity, while the second pulse has lower amplitude for normal display operation. This parameter change enables the display to maintain particle distribution uniformity in vertical orientation without sacrificing compactness
2Stability of the object's composition
If a strong driving signal is applied to move electro-phoretic particles against gravity, then particle distribution can be maintained, but the risk of particle aggregation and display defects increases
Solution Approach 1:
The patent employs periodic dual-pulse signaling where the first strong pulse is applied intermittently before each frame display, followed by a weaker second pulse for actual image rendering. This periodic application of controlled force maintains particle distribution stability without causing continuous agitation that would lead to aggregation and display defects
Solution Approach 2:
The patent applies excessive force only partially - the first strong pulse is used solely for particle redistribution during balancing, while the second weaker pulse handles normal display operation. This partial application of excessive force achieves the necessary particle redistribution without subjecting the system to continuous high-stress conditions that would cause instability
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 effectively addresses the display quality issues by ensuring the proper positioning of electro-phoretic particles, enhancing the display's ability to accurately represent colors, particularly in reducing the yellowish tint of black frames.
Implementation Method 1
the charged particles thereof rely on the embedded electrical field to move
Implementation Method 2
are also affected by gravitational field
Data Source
AI summary
An electro-phoretic display including a display panel and a driving circuit. The display panel is configured to display image frames. The driving circuit is coupled to the display panel. The driving circuit is configured to drive the display panel to display the image frames according to a driving signal. The driving signal includes a first pulse and a second pulse. A driving period of the driving signal includes a first stage, a second stage and a driving stage in sequence. The first pulse is located before the driving stage, and the second pulse is located in the second stage. The pulse width of the first pulse is larger than that of the second pulse. In addition, a driving method of an electro-phoretic display is also provided.