OLED Pixel Circuit Alternating Drive for Reliability
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Solution Overview
Problem
The service life of organic light-emitting diodes in active matrix OLED panels is shortened due to constant direct current bias, leading to rapid polarization and decreased light-emitting efficiency.
Innovation Solution
A pixel circuit with at least two electroluminescence elements, where electrodes of one polarity are coupled to different current control terminals and electrodes of the second polarity are connected to a drive unit, allowing for alternating light-emitting states to prevent direct current bias, comprising a switch transistor, storage capacitor, and drive transistor, and a method that controls these elements to alternate between light-emitting and reverse bias states within each frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single organic light-emitting diode is used in the pixel circuit, then the light-emitting display function is achieved, but the organic light-emitting diode constantly stays in direct current bias state causing rapid polarization and shortened service life
Solution Approach 1:
The pixel circuit is divided into multiple sub-pixel circuits, each containing an organic light-emitting diode. By segmenting the single OLED into multiple OLEDs that can be independently controlled, the patent enables alternating light-emitting states where not all OLEDs emit light simultaneously, thereby reducing the duty cycle and preventing constant direct current bias in each individual OLED.
Solution Approach 2:
The patent implements periodic action by controlling different sub-pixels to emit light in alternating frames or time periods. Each organic light-emitting diode is activated only during specific time intervals rather than continuously, creating a periodic on-off pattern that prevents sustained direct current bias and reduces material polarization.
2Duration of action of moving object
If the organic light-emitting diode constantly emits light within the image display period, then the display continuity is maintained, but the threshold voltage rises due to strengthened built-in electric field and light-emitting efficiency deteriorates
Solution Approach 1:
By dividing the display into multiple sub-pixels with individual OLEDs, the patent enables selective activation of different segments at different times. This segmentation allows the display to maintain continuity through spatial multiplexing while individual OLEDs experience reduced temporal duty cycles, preventing threshold voltage accumulation and maintaining light-emitting efficiency.
Solution Approach 2:
The patent introduces dynamic control where the activation state of each sub-pixel changes over time based on frame timing and grayscale requirements. This dynamic switching between light-emitting and non-light-emitting states prevents static direct current bias, allowing the built-in electric field to relax periodically and maintaining stable threshold voltage and light-emitting efficiency.
Data Source
AI summary
Disclosed are a pixel circuit, a method for driving a pixel circuit, and a display panel, display apparatus and electronic product comprising the pixel circuit. The pixel circuit comprises at least two electroluminescence elements, wherein: an electrode in a first polarity of each of the at least two electroluminescence elements is coupled to a corresponding current control terminal; and an electrode in a second polarity of each of the at least two electroluminescence elements is coupled to a drive unit that supplies a drive current for the at least two electroluminescence elements.