Overlapping Electrode Pixel Capacitors for Higher OLED Drive Capacitance
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Solution Overview
Problem
Existing display apparatuses face challenges in achieving increased capacitance in pixel circuits to drive display elements effectively.
Innovation Solution
The display apparatus incorporates a specific electrode configuration with overlapping electrodes and insulating layers to form capacitors, including a first electrode and a second electrode separated by a first insulating layer, a third electrode overlapping both and separated by a second insulating layer, and a fourth and fifth electrode connected to the first and third electrodes, respectively, with protrusions and contact holes for electrical connections, utilizing materials like molybdenum, aluminum, and copper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional capacitor structure is used in the pixel circuit, then the device complexity is reduced, but the capacitance value is insufficient to effectively drive the display element
Solution Approach 1:
The patent implements a nested capacitor structure where a first capacitor and a second capacitor are formed within the same planar footprint by stacking electrode layers at different heights. The first capacitor comprises a first electrode and third electrode separated by a first insulating layer, while the second capacitor comprises the third electrode and a fourth electrode separated by a second insulating layer. This nested configuration effectively doubles the capacitance value within the same area, resolving the contradiction between sufficient capacitance and device complexity.
Solution Approach 2:
The patent transitions from a conventional single-layer capacitor to a multi-layer stacked capacitor structure by adding the vertical dimension. The first capacitor and second capacitor are formed at different vertical levels using multiple insulating layers and electrode patterns, thereby increasing the effective capacitance without expanding the planar area. This dimensional transformation allows the pixel circuit to achieve higher capacitance while maintaining compact design.
2Reliability
If the capacitor area is increased to achieve higher capacitance, then the capacitance value is improved, but the pixel circuit area increases
Solution Approach 1:
The nested capacitor structure allows two capacitors to share the same planar footprint by stacking them vertically. The first capacitor and second capacitor are positioned at different heights using multiple insulating layers, enabling the pixel circuit to achieve doubled capacitance without increasing the planar area. This resolves the contradiction between high capacitance value and compact pixel circuit area.
Solution Approach 2:
The patent utilizes the vertical dimension to increase capacitance by forming stacked electrode layers separated by insulating layers. This three-dimensional capacitor configuration allows the pixel circuit to achieve higher capacitance values without expanding the two-dimensional pixel area, effectively resolving the area-constraint contradiction.
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 enhances the capacitance of storage and hold capacitors, improving the driving current control for display elements, particularly in organic light-emitting diodes, by increasing the effective area and capacitance of the capacitors.
Implementation Method 1
a first insulating layer disposed on the substrate and overlapping the first electrode and the second electrode, a third electrode disposed on the first insulating layer and overlapping the first electrode and the second electrode, a second insulating layer disposed on the first insulating layer and overlapping the third electrode
Data Source
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AI summary
A display apparatus includes a first electrode and a second electrode that are disposed apart from each other on a substrate, a first insulating layer disposed on the substrate and overlapping the first electrode and the second electrode, a third electrode disposed on the first insulating layer and overlapping the first electrode and the second electrode, a second insulating layer disposed on the first insulating layer and overlapping the third electrode, a fourth electrode disposed on the second insulating layer, overlapping the third electrode, and electrically connected to the first electrode, a third insulating layer disposed on the second insulating layer and overlapping the fourth electrode, and a fifth electrode disposed on the third insulating layer, overlapping the fourth electrode, and electrically connected to the third electrode.