Pixel Circuit Driving Method for OLED Display Current Control
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Solution Overview
Problem
In electro-optical devices, such as OLED displays, the miniaturization of pixel circuits leads to challenges in controlling current supplied to light-emitting elements with precision due to variations in transistor threshold voltages, resulting in display nonuniformity and difficulty in achieving high-definition displays with fine precision data signal output.
Innovation Solution
The electro-optical device incorporates a driving circuit with multiple transistors and storage capacitors to compensate for transistor characteristics, allowing precise current supply to light-emitting elements by voltage division and potential shifting, thereby reducing the need for fine precision data signals and minimizing the influence of parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel circuit is miniaturized to achieve high-definition display, then the display resolution is improved, but the precision of current control to light-emitting elements deteriorates due to transistor characteristic variations
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the main current control operation. The pixel circuit first measures the threshold voltage of the transistor and stores it in a capacitor, then uses this pre-acquired information to adjust the drive voltage and compensate for variations. This preliminary measurement and storage of threshold voltage data enables subsequent precise current control despite transistor variations caused by miniaturization.
2Productivity
If the driving capability is increased to charge data lines quickly, then the productivity is improved, but the precision of data signal output deteriorates
Solution Approach 1:
The patent segments the current control process into multiple independent stages: threshold voltage measurement stage, compensation voltage generation stage, and final current drive stage. Each stage is handled by separate circuit components (measurement transistor, compensation capacitor, drive transistor), allowing the system to achieve both fast charging through high-capability drivers and precise control through dedicated compensation circuits operating in sequence.
Data Source
AI summary
An electro-optical device includes a first storage capacitor that has a first electrode and a second electrode, and a second storage capacitor that has a third electrode and a fourth electrode, and a first pixel circuit. The first pixel circuit includes a first transistor having a first gate, a first drain, and a first source, an electro-optical element, a second transistor through which a first data line is electrically connected to the first gate during the second transistor is in an on-state, and a third transistor through which the first gate is electrically connected to the first drain or the first source. The second electrode and the third electrode are electrically connected to the first data line.