OLED Pixel Storage Capacitor Segmentation for Gray Scale Consistency
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Solution Overview
Problem
High-resolution OLED displays face challenges in maintaining sufficient capacitance due to reduced pixel area, leading to decreased storage capacity and potential issues with gray scale consistency.
Innovation Solution
The design incorporates a second storage capacitor that does not overlap with the first storage capacitor, allowing for separate storage capacity maintenance and supplementation, ensuring consistent gray scale display across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel area is reduced to increase resolution, then display resolution is improved, but storage capacity decreases
Solution Approach 1:
The pixel circuit is divided into two separate storage capacitors (first storage capacitor and second storage capacitor) instead of using a single capacitor. This segmentation allows the total storage capacity to be maintained even when the overall pixel area is reduced for high-resolution displays, as each capacitor can be optimized independently for its specific function.
Solution Approach 2:
The second storage capacitor is configured with electrodes on different layers (third electrode on a different layer from the first and second electrodes, with the fourth electrode provided on the third electrode), utilizing vertical stacking to save horizontal space. This dimensional approach allows maintaining sufficient storage capacity in a reduced pixel area by exploiting the third dimension (layer stacking) rather than expanding in the planar dimension.
2Measurement precision
If pixel area is reduced to increase resolution, then display resolution is improved, but gray scale consistency deteriorates
Solution Approach 1:
By dividing the storage function into two separate capacitors with distinct electrode configurations and layer assignments, the circuit can more effectively maintain stable voltage levels for gray scale control. The first storage capacitor handles primary storage while the second storage capacitor provides supplementary capacity and stability, ensuring consistent gray scale performance even in high-resolution displays with reduced pixel areas.
Solution Approach 2:
The invention changes the structural parameters of the storage capacitors by placing electrodes on different layers and insulating them from overlapping electrodes of the first capacitor. This parameter change optimizes the electrical characteristics and capacitance values, ensuring stable gray scale consistency in high-resolution displays where pixel area is constrained.
3Device complexity
If storage capacitor structure is simplified, then device complexity is reduced, but storage capacity is insufficient
Solution Approach 1:
The second storage capacitor utilizes a layered structure where the third electrode is on a different layer from the first and second electrodes, with the fourth electrode provided on the third electrode. This vertical stacking approach increases storage capacity without proportionally increasing planar area or overall device complexity, as the structure efficiently uses the vertical dimension available in the pixel circuit.
Solution Approach 2:
The multi-layer electrode structure serves multiple functions: the first and second electrodes form the first storage capacitor, while the third and fourth electrodes on different layers form the second storage capacitor. This universal structure design allows the circuit to achieve enhanced storage capacity without adding separate discrete capacitor components, thereby limiting the increase in device complexity while improving storage capacity.
Data Source
AI summary
An organic light-emitting diode (OLED) display is disclosed. In one aspect, the OLED display includes a plurality of pixels, each including a driving thin film transistor (TFT) formed over a substrate and including a driving gate electrode, a first storage capacitor comprising a first electrode and a second electrode, and a second storage capacitor comprising a third electrode and a fourth electrode. The first electrode is electrically connected to the driving gate electrode and the second electrode is formed over the first electrode and electrically insulated from the first electrode. The third electrode is electrically connected to the first electrode, is formed on a different layer from each of the first and second electrodes, and does not overlap the second electrode. The fourth electrode is formed over the third electrode and electrically insulated from the third electrode.