Parallel Dual-Light-Emitter Pixel Circuit for Uniform Grayscale Luminance
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Solution Overview
Problem
Existing display devices face complexity in driving circuits and inefficiencies in luminance uniformity and power consumption due to the need for separate pixel data and wires for multiple light-emitting elements, particularly affecting green and blue pixels.
Innovation Solution
A pixel circuit design with two light-emitting elements having different threshold voltages connected in parallel, controlled by a single switch element, allowing independent operation and improved luminance uniformity through a simple circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two light-emitting elements are driven individually with separate pixel data and wires, then luminance uniformity and lifetime are improved, but circuit complexity increases
Solution Approach 1:
The patent merges the control of two light-emitting elements into a single pixel circuit by sharing common wiring (ELVDD, ELVSS, data lines) and using a unified driving transistor. The two light-emitting elements are connected in parallel to the second node, allowing them to be driven by the same pixel circuit without requiring separate pixel data and wires, thus reducing circuit complexity while maintaining luminance uniformity through careful design of the driving mechanism
Solution Approach 2:
The pixel circuit is designed with multi-functionality to control both light-emitting elements simultaneously. The driving transistor and capacitor serve dual purposes in managing the voltage and current for both EL1 and EL2, allowing a single pixel circuit structure to perform the function of what would traditionally require two separate circuits, thereby reducing overall circuit complexity
2Reliability
If two light-emitting elements are driven individually with separate pixel data and wires, then luminance uniformity is improved, but the number of components increases
Solution Approach 1:
The patent combines multiple components into a shared infrastructure. Both light-emitting elements share common power supply lines (ELVDD, ELVSS), data lines, and the same pixel circuit components (driving transistor, capacitor). This merging approach reduces the total quantity of components needed compared to having completely separate circuits for each light-emitting element, while still achieving luminance uniformity through the unified control mechanism
3Reliability
If two light-emitting elements are connected in parallel with different threshold voltages, then luminance uniformity across grayscale levels is improved, but power consumption optimization becomes more challenging
Solution Approach 1:
The patent applies local quality by assigning different threshold voltages to different light-emitting elements based on their specific characteristics and requirements. EL1 and EL2 have different threshold voltages tailored to their individual performance needs, allowing each element to operate optimally within the parallel configuration. This localized optimization enables luminance uniformity across grayscale levels while the unified pixel circuit manages power consumption through coordinated control of both elements
Data Source
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AI summary
A pixel circuit according to an example and a display device including the same are disclosed. A pixel circuit includes a driving element including a first electrode connected to a first power line, a gate electrode connected to a first node, and a second electrode connected to a second node; a switch element configured to supply a data voltage to the first node in response to a gate signal; a capacitor connected between the first node and the second node; and a first light-emitting element and a second light-emitting element connected in parallel between the second node and a second power line, wherein the first light-emitting element and the second light-emitting element have different threshold voltages.