TFT Array Panel Storage Electrode Overlap Design
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Solution Overview
Problem
Conventional liquid crystal display (LCD) panels face issues with aperture ratio reduction and inconsistent storage capacitance due to light leakage near openings in color filters, which affects display performance.
Innovation Solution
A thin film transistor (TFT) array panel design that includes a substrate with a first storage electrode, a TFT separated from the storage electrode, an insulating layer with openings, and a pixel electrode overlapping the storage electrode, with the boundary of the pixel electrode partially within the opening, ensuring appropriate storage capacitance and minimizing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If openings are formed in color filters to ensure storage capacitance, then storage capacitance is improved, but light leakage occurs near the openings
Solution Approach 1:
A black matrix layer is introduced as an intermediary substance between the opening and the liquid crystal layer to block light leakage. The black matrix is specifically positioned to cover the peripheral region of the opening where light leakage occurs, while maintaining the opening's functionality for storage capacitance. This mediator approach allows both requirements to coexist.
Solution Approach 2:
The color filter structure is modified to have different properties in different regions: the central opening region maintains transparency for capacitance, while the peripheral region around the opening is covered by the black matrix to block light leakage. This local differentiation allows each region to fulfill its specific function without compromising the other.
2Object-generated harmful factors
If the pixel electrode boundary is positioned within the opening to block light leakage, then light leakage is reduced, but the aperture ratio decreases
Solution Approach 1:
The black matrix serves as a mediator that blocks light leakage without requiring the pixel electrode to extend into the opening. This allows the pixel electrode to maintain its optimal position for maximum aperture ratio while the black matrix handles the light leakage blocking function separately.
Solution Approach 2:
The light leakage blocking function is segmented from the pixel electrode structure and assigned to a separate black matrix layer. This segmentation allows the pixel electrode to focus on maximizing aperture ratio while the black matrix independently handles light leakage, avoiding the trade-off between the two functions.
3Quantity of substance
If the pixel electrode overlaps the storage electrode to form storage capacitor, then storage capacitance is ensured, but light leakage occurs at the overlapping boundary near openings
Solution Approach 1:
The black matrix is positioned as an intermediary layer between the pixel electrode and the opening, specifically covering the boundary region where light leakage occurs. This allows the pixel electrode to maintain its overlapping position with the storage electrode for capacitance while the black matrix blocks light leakage at the critical boundary area.
Solution Approach 2:
The black matrix is strategically positioned only at the peripheral boundary region of the opening where light leakage occurs, while leaving the central opening area and the overlapping region between pixel and storage electrodes intact. This local placement ensures storage capacitance is maintained while blocking light leakage at the problematic boundary.
Data Source
AI summary
A thin film transistor (“TFT”) array panel according to an exemplary embodiment of the present invention includes a substrate, a first storage electrode formed on the substrate, a first TFT formed on the substrate and separated from the first storage electrode, a first insulating layer formed on the first storage electrode and the first TFT and having a first opening disposed on the first storage electrode, a pixel electrode connected to the first TFT and overlapping the first storage electrode in the first opening, and a second insulating layer disposed between the first storage electrode and the pixel electrode in the first opening, wherein at least a portion of the boundary of the pixel electrode overlaps the first storage electrode and is disposed in the first opening. Accordingly, storage appropriate capacitance is ensured and a reduction of the aperture ratio may be decreased.