OLED Drive TFT K Value Detection via Dual Voltage Current Integration
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Solution Overview
Problem
The aging of OLED drive thin film transistors and threshold voltage shifts lead to a decline in OLED display quality, necessitating accurate detection and compensation of the K value to maintain performance.
Innovation Solution
A method involving a sub pixel driving circuit with three thin film transistors, a capacitor, and a detection process circuit, which uses scan and detection signals to calculate the K value of the drive thin film transistor through current integration and conversion, allowing for precise K value compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only threshold voltage compensation is implemented, then the device complexity is reduced, but the measurement precision of transistor parameters is insufficient
Solution Approach 1:
The detection circuit shares the drive thin film transistor, capacitor, and other components with the normal display circuit, allowing these components to serve dual purposes: driving the OLED during display operation and detecting K values during compensation mode, thereby reducing the need for completely separate detection hardware
Solution Approach 2:
A detection signal is introduced as an intermediary control mechanism that switches the circuit between normal display mode and detection mode. This detection signal enables the same hardware to perform different functions without requiring permanent dedicated detection components for each pixel
2Measurement precision
If dedicated detection circuits are added to each pixel, then the measurement precision of K value is improved, but the device complexity increases
Solution Approach 1:
The drive thin film transistor and capacitor are designed to serve dual functions: they operate as functional components during normal display driving and as measurement components during K value detection. This eliminates the need for separate dedicated detection circuits at each pixel location
Solution Approach 2:
The detection circuit merges the drive circuit components (thin film transistor, capacitor) with the detection functionality. By combining these elements, the patent achieves accurate K value measurement without adding separate detection hardware to each pixel, thereby reducing overall device complexity
3Measurement precision
If multiple detection signals are used, then the measurement precision of K value is improved, but the loss of time for detection increases
Solution Approach 1:
The detection process uses periodic switching between normal display mode and detection mode through detection signals. Multiple detection voltages are applied in sequential periods rather than simultaneously, allowing accurate measurements to be obtained over time without requiring all measurements to occur at once, thus managing the time trade-off
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method accurately detects and compensates the K value of each pixel, enhancing OLED display quality by maintaining consistent performance over time.
Implementation Method 1
a current integrator electrically coupled to the drain of the third thin film transistor
Implementation Method 2
an analog to digital converter electrically coupled to the CDS sampler
Data Source
AI summary
The present invention provides a K value detection method of an OLED drive thin film transistor. The method sets the data signal to provide two different data voltages to make the drive thin film transistor form two different gate-source voltages, and then the currents flowing through the drive thin film transistor under the two different gate-source voltages are detected by the external detection process circuit, and the central process unit calculates and obtains the threshold voltage of the OLED drive thin film transistor according to the two gate-source voltages, the two current data and the formula based on the current formula for the driving thin film transistor. The present invention can accurately acquires the K value of the drive thin film transistor of each pixel in the OLED display element to improve the K value compensation result of the OLED drive thin film transistor for promoting the OLED display quality.