Pixel Structure Aperture Ratio via Vertical Capacitor Stacking
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Solution Overview
Problem
Existing pixel structures in liquid crystal displays face challenges in achieving high aperture ratios due to the expansion of non-transparent capacitor electrodes and the coupling effects between pixel electrodes and data lines, which limit both image quality and display aperture.
Innovation Solution
A pixel structure with two metal layers is designed, including a channel layer, patterned metal layers, insulation layers, and a pixel electrode, where the capacitor electrode is positioned between the data line and the pixel electrode, allowing for increased storage capacitance and aperture ratio, and a fabrication method using five photomasks to easily form this structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If capacitor electrodes are expanded to increase storage capacitance, then storage capacitance is improved, but aperture ratio deteriorates
Solution Approach 1:
The patent utilizes the third dimension (vertical stacking) by forming capacitor electrodes in multiple layers above and below the pixel electrode plane. This allows storage capacitance to be increased without expanding the horizontal footprint, thereby maintaining the aperture ratio while achieving sufficient capacitance through vertical space utilization.
Solution Approach 2:
The capacitor electrodes are nested within the pixel structure by positioning them in overlapping regions with the pixel electrode. The first and second capacitor electrodes are formed in different vertical layers, with one electrode nested above or below the pixel electrode, allowing compact integration without occupying additional lateral space.
2Reliability
If distance between pixel electrodes and data lines is increased to reduce coupling effects, then display quality is improved, but aperture ratio deteriorates
Solution Approach 1:
The patent introduces a shielding electrode as an intermediary element positioned between the pixel electrode and the data line. This shielding electrode acts as a mediator that blocks or reduces the capacitive coupling effects between the pixel electrode and data line, allowing them to be placed closer together without compromising display quality, thereby maintaining a high aperture ratio.
3Quantity of substance
If non-transparent conductive materials are used for capacitor electrodes to increase capacitance, then storage capacitance is improved, but aperture ratio deteriorates
Solution Approach 1:
The patent applies different material properties to different regions: transparent or translucent conductive materials are used for capacitor electrodes in regions where light transmission is critical (such as beneath the pixel electrode), while non-transparent materials can be used in regions where light transmission is less critical. This localized material selection allows sufficient capacitance to be achieved without significantly compromising the overall aperture ratio and display brightness.
Data Source
AI summary
A pixel structure and its fabrication method are provided. The pixel structure includes a channel layer, a first patterned metal layer, a first insulation layer, a second patterned metal layer, a second insulation layer, and a pixel electrode. The first patterned metal layer includes a data line, a source, and a drain. The first insulation layer has a first opening exposing the drain. The second patterned metal layer includes a scan line and a capacitor electrode. The capacitor electrode has at least one first portion overlapping the data line. The second insulation layer has a second opening communicating with the first opening to expose the drain. The pixel electrode is connected to the drain through the first opening and the second opening and at least overlaps the first portion of the capacitor electrode.