Display Device Pixel Electrode Control for Viewing Angle and Gamma
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Solution Overview
Problem
Liquid crystal display devices face issues with narrow viewing angles, gamma distortion, and reduced visibility and transmittance due to the limitations of patterned vertically aligned (PVA) and super-PVA modes, particularly in controlling electric capacitance and supplying different voltages to pixel electrodes.
Innovation Solution
A display device with a pixel electrode configuration including a main and sub pixel electrode connected to separate gate lines and a control thin film transistor, where a control voltage is generated based on the gray scale of an image signal to adjust the transmittance ratio, and specific gate and data signals are supplied to activate the electrodes at different times to control the liquid crystal layer's capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PVA mode with cutting pattern is used to improve viewing angle, then viewing angle is improved, but gamma distortion increases and visibility decreases
Solution Approach 1:
The pixel electrode is divided into a main pixel electrode and a sub pixel electrode, which are independently controlled by separate gate lines. This segmentation allows different voltage control for different regions, enabling improved viewing angle characteristics while maintaining proper gamma response through independent electrode management.
2Ease of operation
If SPVA mode with coupling capacitance is used to supply different voltages, then voltage control is improved, but transmittance and visibility become lower
Solution Approach 1:
A control thin film transistor is introduced as an intermediary element to manage the voltage distribution between the main and sub pixel electrodes. This intermediary component enables precise control of the capacitance coupling, allowing optimal voltage differentiation that improves ease of operation while maintaining adequate transmittance levels.
3Ease of operation
If sub pixel electrode is added to control capacitance, then voltage control is improved, but device complexity increases
Solution Approach 1:
The control thin film transistor is merged with the existing pixel structure, sharing the same substrate and integration process. The sub pixel electrode is combined with the main pixel electrode within the same pixel region, allowing improved voltage control functionality to be achieved with minimal increase in overall device 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 configuration improves visibility and transmittance by controlling the transmittance ratio of sub and main pixel electrodes, reducing gamma curve differences and enhancing the viewing angle, thereby increasing the contrast ratio and overall display performance.
Implementation Method 1
a liquid crystal layer interposed between the first and second substrates
Implementation Method 2
liquid crystals are vertically aligned without application of an electric field
Implementation Method 3
a thin film transistor
Implementation Method 4
a gate driver outputs a first gate signal to the first gate line and a second gate signal to the second gate line
Data Source
AI summary
A display device including a first gate line and a second gate line that extend in parallel with each other, a data line crossing the first and second gate lines to form a pixel region, a pixel electrode in the pixel region and including a main pixel electrode and a sub pixel electrode, which are connected to the first gate line and the data line, a control thin film transistor connected to the second gate line and the sub pixel electrode, and a gate driver. The gate driver outputs a first gate signal to the first gate line and a second gate signal to the second gate line. The first gate signal activates the first gate line during a first time and a second time following the first time, and the second gate signal activates the second gate line during the first time but not the second time.