OLED Pixel Circuit With Global Initialization for Higher Resolution
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Solution Overview
Problem
Conventional OLED display pixel architectures that support in-pixel threshold voltage compensation require a large number of transistors, limiting the maximum achievable resolution and causing non-uniformity in pixel-to-pixel luminance.
Innovation Solution
A display pixel design with a reduced transistor count, utilizing three thin-film transistors, two capacitors, and an optional additional capacitor, along with a shared emission transistor or row-wise power supply, to achieve in-pixel threshold voltage compensation without additional transistors, enhancing pixel-to-pixel luminance uniformity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional OLED display pixel architectures with in-pixel threshold voltage compensation are used, then luminance uniformity is improved, but the transistor count increases
Solution Approach 1:
The patent merges the emission transistor from individual pixel circuits into a shared common emission transistor that serves multiple pixels. This consolidation reduces the total transistor count per pixel while maintaining the threshold voltage compensation functionality through the combination of the drive transistor, select transistor, and storage capacitor configuration.
Solution Approach 2:
The common emission transistor serves as a universal component for multiple pixels, performing the emission control function that would otherwise require dedicated transistors in each pixel. This multi-functional approach allows the same transistor to control light emission across multiple pixel elements, reducing overall device complexity.
2Manufacturing precision
If conventional OLED display pixel architectures with in-pixel threshold voltage compensation are used, then luminance uniformity is improved, but the display resolution is limited
Solution Approach 1:
By merging emission transistors into a shared common structure, the patent reduces the area occupied by transistor components in each pixel. This area reduction enables higher pixel density arrangements, thereby improving display resolution while maintaining the luminance uniformity benefits of threshold voltage compensation.
Solution Approach 2:
The patent reorganizes the pixel circuit architecture from a planar arrangement with dedicated transistors to a more compact configuration utilizing shared common transistors. This dimensional reorganization allows for more efficient space utilization, enabling higher resolution displays with the same physical area.
3Device complexity
If the emission transistor is omitted from each pixel, then the transistor count is reduced, but control precision may be affected
Solution Approach 1:
The common emission transistor serves multiple pixels simultaneously, providing emission control functionality without requiring dedicated transistors in each pixel. This universal approach maintains emission control precision through the coordinated operation of the common transistor with individual pixel drive transistors and storage capacitors.
Solution Approach 2:
The common emission transistor acts as an intermediary component that mediates between the power supply and multiple pixel circuits. It provides the necessary emission control function while allowing individual pixel data to be maintained through the drive transistor and storage capacitor, preserving control precision without requiring per-pixel emission transistors.
Data Source
AI summary
A display may include an array of pixels. A pixel can include an organic light-emitting diode, up to three thin-film transistors, and up to two capacitors. The pixel can include a drive transistor, an emission transistor, and a select transistor. The select transistor can be used to apply a reference voltage to the gate of the drive transistor during a global reset phase and during a global threshold voltage sampling phase and can also be used to apply a data voltage to the gate of the drive transistor during a data programming phase. The drive transistor can receive a power supply voltage that toggles between a low voltage during the global reset phase and a high voltage during other phases of operation. Configured and operated in this way, the pixel need not include separate dedicated anode reset and initialization transistors.