Light-emitting Device Driving Circuit Threshold Voltage Compensation
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Solution Overview
Problem
Conventional circuits for driving pixels in light-emitting displays face challenges due to threshold voltage shifts of driving transistors, affecting emission current and brightness control, especially in low grayscale regions.
Innovation Solution
A light-emitting device driving circuit comprising a delivery capacitor, driving transistor, reset circuit, compensation circuit, and data circuit, where the compensation circuit controls the gate voltage of the driving transistor using a reference voltage to compensate for threshold voltage shifts, enabling precise brightness control and improved resolution by isolating the threshold voltage from emission current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional driving circuits are used, then the circuit structure is simple, but the brightness control precision deteriorates due to threshold voltage shift
Solution Approach 1:
The driving circuit is segmented into functional modules: reset circuit, compensation circuit, and data circuit, each handling specific tasks. The compensation circuit is further divided into first and second compensation circuits that operate at different times, separating the threshold voltage compensation function from the normal driving function to achieve precise brightness control without overwhelming complexity.
Solution Approach 2:
The reset circuit performs preliminary reset action on the driving transistor before the compensation circuit applies threshold voltage compensation. This preliminary reset ensures the transistor starts from a known state, and the subsequent compensation action builds upon this foundation to achieve precise brightness control.
2Measurement precision
If threshold voltage compensation is implemented, then brightness control precision is improved, but the compensation segment duration increases
Solution Approach 1:
The compensation process uses periodic action by alternating between first and second compensation circuits in different time segments. The first compensation circuit operates during a first time segment, then the second compensation circuit operates during a second time segment, creating a periodic compensation pattern that reduces total compensation time while maintaining precision.
Solution Approach 2:
The compensation process uses partial action by dividing the total compensation into two separate compensation circuits that each perform partial compensation functions. This allows the compensation to be distributed over time rather than requiring one excessive long compensation segment, reducing overall time loss.
3Reliability
If threshold voltage shift is not compensated, then the circuit operation is fast, but the emission current control accuracy deteriorates
Solution Approach 1:
The compensation circuits implement feedback by continuously monitoring and adjusting the gate voltage of the driving transistor to compensate for threshold voltage shifts. This feedback mechanism ensures accurate emission current control while the automated nature of the feedback maintains fast operation speed without manual intervention.
Solution Approach 2:
The compensation circuits perform self-service by automatically detecting and correcting threshold voltage shifts without external intervention. The circuit monitors its own state and applies necessary compensation, maintaining both high reliability and fast operation speed through autonomous correction.
Data Source
AI summary
A light-emitting device driving circuit including a light emitting device, a delivery capacitor, a driving transistor, a reset circuit, a compensation circuit, and a data circuit is provided. The delivery capacitor is electrically connected to a low-level voltage. The driving transistor is configured to drive the light-emitting device according to a driving voltage received from a driving voltage line higher than that of the low-level voltage. The reset circuit is configured to determine whether to electrically connect the light-emitting device to the first node. The compensation is configured to receive a reference voltage higher than the low-level voltage to control a gate voltage of the driving transistor through a second node. The data circuit is configured to receive a data voltage to determine whether to electrically connect the data voltage to the compensation circuit and whether to electrically connect the data voltage to the delivery capacitor.