Display Pixel Capacitor Layout for Higher Light Extraction
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Solution Overview
Problem
In display apparatuses, the light emitted from light-emitting devices is often blocked by the pixel driving circuit, leading to decreased light extraction efficiency.
Innovation Solution
The display apparatus incorporates a bank insulating layer defining an emission area, with a light-emitting device and a capacitor electrode having a positive taper shape, reflecting light inward to enhance extraction efficiency and prevent color mixing, while reducing the area occupied by the pixel driving circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel driving circuit is disposed in each pixel area to supply driving current to the light-emitting device, then the light-emitting device can be driven properly, but the light extracted from the light-emitting device is blocked by the pixel driving circuit, decreasing light extraction efficiency
Solution Approach 1:
The invention moves the storage capacitor from the planar pixel area to the vertical dimension by disposing it between the over-coat layer and the bank insulating layer. This three-dimensional arrangement allows the pixel driving circuit to be positioned below the light-emitting device in the vertical direction, eliminating light blocking while maintaining electrical connectivity through conductive layers extending through the over-coat layer.
Solution Approach 2:
The invention segments the pixel structure into distinct functional layers: the light-emitting device is separated from the pixel driving circuit by the over-coat layer, with the storage capacitor positioned in the interstitial space between the over-coat layer and bank insulating layer. This segmentation allows independent optimization of light extraction and circuit functionality.
2Ease of operation
If the pixel driving circuit occupies space in the pixel area, then the light-emitting device can be controlled, but the emission area is reduced and color mixing may occur
Solution Approach 1:
By transitioning to vertical stacking, the invention maximizes the planar emission area while accommodating the pixel driving circuit in the vertical dimension. The over-coat layer with its inclined surface creates a three-dimensional configuration that expands the light-emitting device's horizontal footprint without increasing the occupied pixel area.
Solution Approach 2:
The over-coat layer features an asymmetric inclined surface that slopes downward from the center toward the edges of the emission area. This asymmetric geometry directs light preferentially toward the emission area while providing space for the storage capacitor on the opposite side, effectively separating light propagation and circuit functions within the same pixel area.
3Duration of action of stationary object
If the storage capacitor is disposed in each pixel area to maintain driving current, then the light-emitting device can be driven continuously, but the area occupied by the pixel driving circuit increases
Solution Approach 1:
The storage capacitor is repositioned from a planar arrangement within the pixel driving circuit to a vertical arrangement between the over-coat layer and bank insulating layer. This three-dimensional placement incorporates the capacitor into the vertical stack without expanding the horizontal pixel area, maintaining continuous driving current while preserving emission area.
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
Improves light extraction efficiency and prevents color mixing by reflecting light inward, increasing the size of the emission area and maintaining image quality.
Implementation Method 1
a capacitor electrode having a positive taper shape, reflecting light inward to enhance extraction efficiency and prevent color mixing
Data Source
AI summary
A display apparatus is provided. The display apparatus may include a light-emitting device disposed on an emission area of a device substrate. An over-coat layer may be disposed between the device substrate and the light-emitting device. The over-coat layer may include an over inclined surface extending along an edge of the emission area. A capacitor electrode may cover the over inclined surface. A first electrode of the light-emitting device may include a capacitor region overlapping with the capacitor electrode. A capacitor insulating layer may be disposed between the capacitor electrode and the capacitor region of the first electrode. Thus, in the display apparatus, an emission area may be increased, the light extraction efficiency may be improved, and color mixing may be prevented.