AMOLED Pixel Circuit Sharing for Uniform Brightness and Higher Yield
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Solution Overview
Problem
Existing active-matrix organic light-emitting diode (AMOLED) displays require a large number of transistors in their pixel circuits for brightness compensation, leading to increased complexity, reduced yield, and limited resolution due to layout area constraints.
Innovation Solution
A novel frame-division and pixel circuit-sharing scheme where the array of light emitting elements is divided into groups, allowing multiple elements to share the same pixel circuit, reducing the average number of transistors required while maintaining brightness uniformity, and simplifying gate scanning and light emitting drivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If compensation circuits with extra transistors are added to each pixel circuit, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple light emitting elements into a single pixel circuit unit. Specifically, one pixel circuit controls multiple light emitting elements (e.g., multiple subpixels or pixels) by sharing the driving transistor and compensation circuit components. This consolidation reduces the total transistor count per element while maintaining brightness uniformity through centralized compensation control.
Solution Approach 2:
The pixel circuit is designed with universal components that can serve multiple light emitting elements. The driving transistor and compensation circuitry are configured to function as multi-functional units that can drive and compensate for multiple different light emitting elements, rather than being dedicated to a single element. This universality reduces overall device complexity while maintaining manufacturing precision.
2Manufacturing precision
If more transistors are used per pixel circuit for compensation, then brightness uniformity is improved, but layout area increases
Solution Approach 1:
By merging multiple light emitting elements under a single pixel circuit control, the layout area per element is reduced. The shared compensation circuit and driving transistor occupy common space that would otherwise be replicated multiple times, thereby reducing the total layout area while maintaining brightness uniformity through the shared compensation mechanism.
Solution Approach 2:
The patent reorganizes the pixel array structure by dividing it into groups where each group shares a common pixel circuit. This dimensional reorganization allows multiple elements to be controlled by a single circuit unit, effectively reducing the area footprint per element while maintaining compensation functionality across the entire group.
3Manufacturing precision
If each light emitting element has its own dedicated pixel circuit, then manufacturing precision is maintained, but productivity decreases
Solution Approach 1:
The patent merges multiple light emitting elements into shared pixel circuits, reducing the total number of transistors and components that need to be manufactured. This consolidation improves productivity and yield by reducing the complexity of the manufacturing process, while the shared compensation circuitry maintains brightness uniformity across all elements through centralized control.
Data Source
AI summary
A pixel circuit includes a capacitor, a light emitting control transistor, a driving transistor, and multiple light emitting transistors. The light emitting control transistor includes a gate electrode coupled to a light emitting control signal, a source electrode coupled to a supply voltage, and a drain electrode. The driving transistor includes a gate electrode coupled to the capacitor, a source electrode coupled to the drain electrode of the light emitting control transistor, and a drain electrode. Each light emitting transistor includes a gate electrode coupled to a respective light emitting signal, a source electrode coupled to the drain electrode of the driving transistor, and a drain electrode coupled to a respective light emitting element. Each light emitting signal turns on the respective light emitting transistor during a respective light emitting period within a frame period to cause the respective light emitting element to emit a light. The light emitting control signal turns on the light emitting control transistor during each light emitting period within the frame period.