Array Substrate Control Terminal Shielding for Liquid Crystal Light Leakage
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Solution Overview
Problem
Liquid crystal displays suffer from light leakage in the dark state due to irregular electric fields, leading to increased brightness and reduced contrast, which existing solutions like black matrices cannot effectively address at oblique viewing angles, especially with anisotropic liquid crystal materials.
Innovation Solution
The array substrate design includes a thin film transistor with a control terminal and pixel electrode configuration where the orthographic projection of the control terminal is within the common electrode's projection, creating overlap areas to shield electric fields and prevent liquid crystal deflection, thereby reducing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black matrix is used to block light leakage, then light leakage at normal viewing angles is reduced, but light leakage at oblique viewing angles cannot be effectively addressed and aperture ratio is reduced
Solution Approach 1:
The patent introduces a common electrode as an intermediary element positioned between the pixel electrode and the liquid crystal layer. This common electrode generates an electric field that works in conjunction with the pixel electrode to maintain uniform liquid crystal alignment, thereby preventing light leakage without requiring additional light-blocking structures that would reduce aperture ratio.
Solution Approach 2:
The patent changes the electrical parameters by applying specific voltage potentials to the common electrode relative to the pixel electrode. By controlling the voltage difference between these electrodes, the electric field distribution is optimized to prevent liquid crystal deflection at oblique viewing angles, achieving contrast improvement without structural additions that would reduce aperture.
2Ease of manufacture
If the control terminal is positioned outside the common electrode projection, then manufacturing is simpler, but irregular electric fields cause liquid crystal deflection and light leakage
Solution Approach 1:
The patent applies preliminary anti-action by positioning the control terminal within the common electrode's projection area, which allows the common electrode to pre-establish an electric field that counteracts potential irregularities before they can cause liquid crystal deflection. This proactive positioning prevents light leakage by ensuring uniform field distribution across the pixel area.
Solution Approach 2:
The patent applies local quality by creating a specific spatial relationship where the control terminal is localized within the common electrode projection. This localized positioning ensures that the electric field generated by the control terminal is uniformly distributed only in the necessary pixel region, preventing light leakage without affecting the overall manufacturing process complexity.
3Speed
If anisotropic liquid crystal materials are used to improve response speed, then viewing angle performance improves, but irregular electric fields cause deflection and reduce contrast
Solution Approach 1:
The patent applies equipotentiality by using the common electrode to create a uniform electric field distribution across the liquid crystal layer. This uniform field ensures that anisotropic liquid crystal molecules are aligned consistently, preventing deflection and light leakage while maintaining the fast response characteristics that anisotropic materials provide.
Solution Approach 2:
The patent effectively creates a composite electromagnetic environment by combining the electric fields generated by both the pixel electrode and the common electrode. This composite field structure works synergistically with the anisotropic liquid crystal material to achieve both fast response speed and uniform alignment, preventing light leakage at oblique viewing angles.
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 effectively reduces light leakage and improves contrast by shielding electric fields, achieving a contrast ratio increase from 900:1 to 1000:1 and maintaining performance even with alignment deviations.
Implementation Method 1
the liquid crystals at certain positions are deflected due to the influence of the irregular electric field
Data Source
AI summary
Embodiments of the present application provide an array substrate and a display device. The array substrate includes a plurality of sub-pixel units arranged in an array, each sub-pixel unit includes a base substrate, a thin film transistor, a pixel electrode and a common electrode, the common electrode is on a side of the base substrate, the thin film transistor and the pixel electrode are between the base substrate and the common electrode, the thin film transistor includes a control terminal, a first electrode and a second electrode, the pixel electrode is connected to the second electrode, and the control terminal is in a continuous sheet shape, an orthographic projection of a boundary of the control terminal on the base substrate is within an orthographic projection of the common electrode on the base substrate.