Multi-Picture Element Driving for LCD Viewing Angle Uniformity
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Solution Overview
Problem
Liquid crystal display devices in MVA and ASM modes suffer from viewing angle dependency of γ characteristics, leading to uneven luminance and gradation inversion issues, particularly when observed from the side, which affects image quality in applications like photography and TV broadcasting.
Innovation Solution
The implementation of a multi-picture element driving method, where one display picture element is composed of sub-picture elements with different luminance levels, with the OFF timing of switching elements synchronized to match the phase timing of subsidiary capacity wires, ensuring uniform voltage application and preventing uneven luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-picture element driving method is implemented to improve viewing angle characteristics, then viewing angle dependency of γ characteristics is reduced, but uneven luminance appears in lateral streaks
Solution Approach 1:
The patent applies preliminary action by pre-charging subsidiary capacity wires to specific potentials before the switching element turns OFF. This ensures that at the critical moment when charging completes, all subsidiary capacity wires are at the same potential, preventing uneven luminance. The phase timing of voltage signals is predetermined and synchronized with the switching element's OFF timing to achieve uniform charging across all sub picture elements.
Solution Approach 2:
The patent implements equipotentiality by ensuring all subsidiary capacity wires are at the same potential at the moment when the switching element turns OFF. This is achieved by controlling the phase timing of voltage signals applied to different subsidiary capacity wires, making their potentials equal at the critical charging completion moment. This eliminates potential differences that would cause uneven luminance distribution.
2Productivity
If TN mode is used for wide production margin and excellent productivity, then manufacturing efficiency is improved, but viewing angle characteristics deteriorate with contrast ratio decrease and gradation inversion
Solution Approach 1:
The patent applies segmentation by dividing a single picture element into multiple sub picture elements (first and second sub picture elements). Each sub picture element is connected to separate subsidiary capacity wires that can be independently controlled. This segmentation allows different voltage signals to be applied to different regions, enabling improved viewing angle characteristics while maintaining the TN mode structure for manufacturing efficiency.
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 effectively reduces uneven luminance and gradation inversion, enhancing viewing angle characteristics and maintaining image quality across different observation angles.
Implementation Method 1
a long axis of a liquid crystal molecule with positive permittivity anisotropy is oriented substantially in parallel to the surface of substrates, and the long axis of a crystal liquid molecule is twisted approximately 90° between the above and below substrates in a thickness direction of a liquid crystal layer. Applying a voltage on this liquid crystal layer allows the liquid crystal molecule to stand in parallel to an electric field
Data Source
AI summary
In a liquid crystal display device performing multi-picture element driving, gate OFF timing of a switching element connected between each sub picture element and a signal line is matched with phase timing when all the subsidiary capacity wires are at the same potential. This prevents the occurrence of uneven luminance appearing in a lateral streak.