Transparent Electrode Placement for Aperture Ratio in VR Displays
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Solution Overview
Problem
High-definition liquid crystal display devices, such as those used in virtual reality viewers, face challenges in controlling the liquid crystal layer near contact holes and securing sufficient capacitance due to reduced pixel areas, leading to inefficiencies in display quality and alignment.
Innovation Solution
The configuration of a display device with a first transparent electrode located in the center of a pixel region, connected to a second transparent electrode through a contact hole, and a third transparent electrode with an opening, allows for improved alignment and capacitance without overlapping with signal or scanning lines, enhancing display quality and light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the contact hole is provided near the boundary of pixels to avoid overlapping with signal lines, then the manufacturing complexity is reduced, but the effective aperture ratio decreases due to the need for pixel electrode spacing
Solution Approach 1:
The patent moves the contact hole from the conventional position near the pixel boundary to the center of the pixel region, utilizing the central area more effectively. This dimensional repositioning allows the contact hole to overlap with the pixel electrode without causing short circuits, as the electrode pattern is designed to accommodate the central contact hole while maintaining isolation from adjacent pixels through insulating layers and electrode geometry control.
Solution Approach 2:
The pixel electrode is designed with a dual function: it serves as both the display electrode and the isolation structure for adjacent pixels. By extending the pixel electrode to cover the central contact hole and using insulating layers selectively, the electrode pattern achieves both electrical connection through the contact hole and electrical isolation from neighboring pixels, eliminating the need for separate spacing structures.
2Measurement precision
If the pixel area is reduced to achieve higher definition (2000 ppi or more), then the display resolution is improved, but the capacitance between pixel electrodes and common electrode becomes insufficient
Solution Approach 1:
The patent introduces a third transparent electrode positioned between the pixel electrode and the common electrode, creating an additional capacitive coupling dimension. This multi-layer electrode structure increases the effective capacitance by adding another interface for electrical interaction, compensating for the reduced pixel area while maintaining high resolution display capabilities.
Solution Approach 2:
The patent employs a nested electrode structure where the third transparent electrode is positioned within the space between the pixel electrode and the common electrode. This nested configuration maximizes the use of available vertical space to create additional capacitance without increasing the horizontal pixel area, thereby maintaining high definition while securing sufficient capacitance for liquid crystal alignment.
3Reliability
If the pixel electrode is spaced apart from adjacent pixel electrodes to prevent short circuits through contact holes, then the electrical isolation is improved, but the effective aperture ratio decreases
Solution Approach 1:
The pixel electrode pattern is designed to perform multiple functions simultaneously: it provides electrical connection through the central contact hole, maintains isolation from adjacent pixels through its geometric configuration and insulating layer coverage, and maximizes the effective aperture area by eliminating the need for external spacing structures. The electrode geometry is optimized to extend over the contact hole while being controlled by insulating layers to prevent short circuits.
Solution Approach 2:
The patent introduces insulating layers as intermediary elements that enable the pixel electrode to extend to the center of the pixel region without causing short circuits. These insulating layers selectively cover portions of the electrode pattern, allowing the electrode to reach the central contact hole while maintaining electrical isolation from adjacent pixels, thereby eliminating the need for spacing gaps and increasing the effective aperture ratio.
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 improves the effective aperture ratio and light transmittance of the display panel, maintaining high-definition display quality even with reduced pixel areas by optimizing the placement of electrodes and the formation of fringing fields for better liquid crystal alignment.
Implementation Method 1
a third transparent electrode overlaid on the first transparent electrode and the second transparent electrode... the outer periphery of the first transparent electrode intersects an edge of the opening at eight points
Data Source
AI summary
According to one embodiment, a display device includes a first substrate, a second substrate opposed to the first substrate, and a liquid crystal layer provided between the first substrate and the second substrate. The first substrate includes a first signal line and a second signal line and being adjacent to each other in a first direction, a first scanning line and a second scanning line and being adjacent to each other in a second direction intersecting the first direction, a semiconductor layer connected to the first signal line and the first scanning line, a first transparent electrode in contact with the semiconductor layer, an organic insulating layer including a contact hole, and a second transparent electrode in contact with the first transparent electrode.