Black Matrix Overlap Boosts LCD Storage Capacitance
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Solution Overview
Problem
The capacitance of storage capacitors in liquid crystal display (LCD) devices is insufficient, which affects image quality by not effectively maintaining image data signals during a frame period.
Innovation Solution
The design includes a black matrix with horizontal and vertical portions that overlap the pixel and common electrodes, increasing the overlapping area between them, thereby enhancing the capacitance of the storage capacitor. The black matrix is strategically positioned to cover parts of the pixel electrode and common electrode, specifically with the vertical portion overlapping the branch electrodes, which are designed to be smaller in area than non-overlapping sections, and has a width ranging from 2 μm to 13 μm, defined by a specific height formula.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the black matrix is designed to overlap the pixel electrode and common electrode, then the capacitance of the storage capacitor is increased, but the area of the pixel electrode is reduced
Solution Approach 1:
The black matrix is designed with different coverage areas in different regions. The vertical portion covers only a specific region of the pixel electrode (branch electrodes) rather than the entire pixel electrode area. This local coverage strategy increases the overlapping area between pixel electrode and common electrode to enhance capacitance, while minimizing the reduction of overall pixel electrode area that would affect display quality.
2Reliability
If the vertical portion of the black matrix is made wider to increase overlapping area, then the capacitance is enhanced, but the light blocking area increases
Solution Approach 1:
The width of the vertical portion of the black matrix is precisely controlled within the range of 2 μm to 13 μm. This parameter optimization ensures sufficient overlapping area with the pixel electrode to enhance capacitance while maintaining the light blocking function within acceptable limits. The height is also controlled by the formula W×0.11≦H≦W×1.5 to achieve the optimal balance.
3Reliability
If the pixel electrode area overlapping the black matrix is reduced to enhance capacitance, then the storage capacitor performance is improved, but the display area is reduced
Solution Approach 1:
The black matrix vertical portion is positioned to overlap specifically with the branch electrodes of the pixel electrode, which are peripheral structures. This local positioning strategy enhances the capacitance by increasing the overlapping area between pixel electrode and common electrode in the critical region, while minimizing the impact on the overall display area formed by the main pixel electrode structure.
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 increases the capacitance of the storage capacitor, improving the ability to maintain image data signals and enhance image quality by increasing the overlapping area between the pixel and common electrodes.
Implementation Method 1
increasing the overlapping area between the pixel electrode and the common electrode, thereby enhancing the capacitance of the storage capacitor
Data Source
AI summary
A liquid crystal display (LCD) device includes: a first substrate and a second substrate disposed opposite to each other; a liquid crystal layer disposed between the first substrate and the second substrate; a gate line and a data line disposed on the first substrate; a transistor connected to the gate line and the data line; a pixel electrode disposed in a pixel region of the first substrate; a connecting electrode connecting the pixel electrode and the transistor; a common electrode overlapping the pixel electrode; a protection layer disposed between the pixel electrode and the common electrode; and a black matrix disposed on the protection layer, the black matrix defining the pixel region. The black matrix includes: a horizontal portion extending along the gate line and a vertical portion extending along the data line and overlaps the data line and at least one of the pixel electrode and the common electrode.