Pixel Circuit Body Potential Control for Display Uniformity
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Solution Overview
Problem
Existing pixel drive circuits suffer from poor display uniformity due to random offsets caused by individual differences, leading to significant amplification of small signals and display mura, especially as the drive current increases.
Innovation Solution
A pixel circuit design that includes a pixel drive circuit and a pixel compensation circuit, where the body potential of the drive transistor is set to be lower than the sum of the cathode potential and crossover voltage of the organic light-emitting element, increasing the source-substrate voltage potential and thereby reducing the effect of random offsets on the drive current, while maintaining high brightness capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the drive current is increased to achieve high brightness, then the brightness is improved, but the random offset is significantly amplified resulting in poor uniformity and display mura
Solution Approach 1:
The patent changes the voltage parameters of the drive transistor by setting the body potential to be lower than the sum of cathode potential and crossover voltage (Vbody < Vcom + Voled). This parameter change increases the source-substrate voltage potential, which increases the threshold voltage and reduces the gain, thereby reducing the amplification of random offset while maintaining high brightness capability through increased drive current
2Measurement precision
If the gain is increased to amplify small signals, then the signal amplification is improved, but the random offset is significantly amplified resulting in display mura
Solution Approach 1:
The patent reduces the gain by changing the voltage parameters of the drive transistor. By setting the body potential lower than the sum of cathode potential and crossover voltage, the threshold voltage increases, which reduces the transconductance and gain of the transistor. This reduces the amplification effect on random offset signals while maintaining adequate signal amplification for normal operation
3Manufacturing precision
If the threshold voltage is increased to reduce random offset effect, then the display uniformity is improved, but the drive current decreases resulting in reduced brightness
Solution Approach 1:
The patent simultaneously optimizes multiple voltage parameters: it increases the threshold voltage by increasing the source-substrate voltage potential (reducing gain and random offset amplification), while also increasing the drive current by adjusting the cathode potential and crossover voltage relationship. This dual optimization achieves both improved uniformity and maintained brightness
Data Source
AI summary
Provided are a pixel circuit, a silicon-based display panel, and a display device. The pixel circuit includes a pixel drive circuit and a pixel compensation circuit; the pixel drive circuit includes a drive transistor and an organic light-emitting element; the drive transistor includes an output terminal and a body terminal, where the output terminal is connected to an anode of the organic light-emitting element, and a cathode of the organic light-emitting element is connected to a cathode signal input terminal and configured to receive a cathode potential inputted from the cathode signal input terminal, the cathode potential being fixed; the body terminal is connected to the pixel compensation circuit at a first node, and a potential of the first node is a body potential; and the cathode potential Vcom, a crossover voltage Voled of the organic light-emitting element, and the body potential Vbody satisfy that Vcom+Voled>Vbody.