Pixel Bias Transistors for Afterimage Recovery
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Solution Overview
Problem
Display devices experience afterimages due to changes in characteristics of driving transistors and light emitting elements, leading to persistent luminance issues and image retention.
Innovation Solution
A display device pixel configuration with a light source unit, transistors, and bias transistors, where specific bias voltages are applied during distinct periods of a frame to control and initialize the driving current, reducing afterimage occurrence by managing the gate-source voltage and anode voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bias voltages are applied continuously to control transistor characteristics, then afterimage recovery is improved, but power consumption increases
Solution Approach 1:
The patent applies bias voltages periodically rather than continuously. Specifically, first and second bias voltages are applied during specific periods (such as horizontal blanking periods or non-display periods) when no image is being displayed, allowing the transistor characteristics to be recovered without consuming power during active display periods.
Solution Approach 2:
The patent applies bias voltages in advance during non-display periods before the next image is displayed. This preliminary action resets the transistor characteristics and reduces afterimage effects before they can manifest, ensuring optimal display performance for the upcoming frame while avoiding continuous power consumption.
2Reliability
If multiple bias transistors are added to control voltages during different periods, then afterimage recovery is improved, but device complexity increases
Solution Approach 1:
The patent designs bias transistors that can serve multiple functions. The first and second bias transistors are configured to apply different bias voltages during different periods, allowing a single transistor structure to perform multiple voltage control functions rather than requiring separate dedicated transistors for each function.
Solution Approach 2:
The patent combines the voltage control functions into a unified circuit architecture where bias transistors work together with the driving transistor and storage capacitor in an integrated manner. The bias transistors share control signals and voltage lines with other pixel components, reducing overall circuit complexity compared to separate independent control circuits.
Data Source
AI summary
A pixel according to some embodiments includes a light source unit, a first transistor coupled between a first power source and a first node, and configured to control a driving current applied to the light source unit, a first bias transistor coupled between a first bias power source and a gate electrode of the first transistor, and a second bias transistor coupled between a second bias power source and a second node that is electrically coupled to an anode of the light source unit, wherein the first bias transistor and the second bias transistor are configured to be turned on during a first period before a data voltage is applied among one frame, and wherein the second bias transistor is configured to be turned on at least once during a second period after the data voltage is applied among the one frame.