Liquid Crystal Display Drive Voltage Waveform Optimization
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Solution Overview
Problem
MVA type liquid crystal display panels suffer from slow response times when converting black displays to low brightness halftone displays, leading to brightness over-shoot and poor display frames due to the lack of grinding treatment on the alignment film and excessive rotation torque at higher drive voltages.
Innovation Solution
A liquid crystal display device with protrusions on the electrodes, where the drive voltage is adjusted in a specific waveform to optimize the rotation torque of liquid crystal molecules, with higher voltages applied in the front half of a frame period and equal or lower voltages in the rear half, and subsequent frame periods, to enhance response speed and reduce over-shoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a drive voltage of 3V or more is applied to convert black display to high brightness halftone display or white display, then the rotation torque of liquid crystal molecules becomes large and response speed increases, but the liquid crystal molecules exceed the target direction causing brightness over-shoot and poor display frame
Solution Approach 1:
The patent applies periodic voltage pulses with different amplitudes in sequential stages: an initial high voltage pulse (3V or more) to generate large rotation torque and accelerate liquid crystal molecule response, followed by subsequent voltage adjustments to fine-tune the molecular orientation. This periodic action with varying voltage levels enables the liquid crystal molecules to reach the target direction accurately without excessive overshoot, thereby improving both response speed and display frame quality.
2Ease of manufacture
If no grinding treatment is performed on the alignment film in MVA type liquid crystal display panel, then the manufacturing process is simplified, but the directions of the long axes of liquid crystal molecules in some small areas are in multiple directions when no externally applied voltage is present, resulting in slow response speed when converting black display to low brightness halftone display
Solution Approach 1:
The patent applies a preliminary high voltage pulse (3V or more) at the beginning of the frame period to pre-align the liquid crystal molecules in the desired direction before the actual display content is rendered. This preliminary action overcomes the initial multi-directional disorder of molecules caused by the absence of grinding treatment, enabling faster response speed when converting from black display to low brightness halftone display while maintaining the simplified manufacturing process without grinding treatment.
3Loss of time
If the drive voltage is increased to improve the response speed when converting black display to low brightness halftone display, then the response time decreases, but the brightness over-shoot phenomenon occurs and the display frame quality deteriorates
Solution Approach 1:
The patent employs periodic voltage pulses with optimized amplitude and duration parameters. A high voltage pulse is applied initially to reduce response time, followed by subsequent voltage adjustments within the same frame period to correct any overshoot. This periodic voltage control enables the system to achieve fast response while maintaining accurate brightness levels and good display frame quality, resolving the contradiction between response time and display quality.
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 significantly shortens the response time for converting black displays to low brightness halftone displays, minimizes brightness over-shoot, and maintains a stable display frame, improving the overall performance of the liquid crystal display panel.
Implementation Method 1
liquid crystal display device having negative dielectric anisotropy
Data Source
AI summary
A liquid crystal display device and a driving method thereof are provided. The drive circuit of the liquid crystal display device outputs a drive voltage applied between the first electrode and the second electrode of a pixel. When a transmittance of the sub-pixel is changed from a first transmittance to a second transmittance higher than the first transmittance in a first frame period, the drive voltage is higher than a first target drive voltage corresponding to the second transmittance in a front half period of the first frame period, the drive voltage is equal to the first target drive voltage in a rear half period of the first frame period, and the drive voltage is equal to the first target drive voltage in other frame periods after the first frame period.