Pixel Driving Circuit Threshold Voltage Compensation
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Solution Overview
Problem
Active matrix organic light-emitting diode (AMOLED) displays face non-uniformity in image display due to variations in threshold voltages of driving transistors, affecting the driving current and overall image quality.
Innovation Solution
A pixel driving circuit design incorporating a light emitting device, a storage capacitor, and four switching units, where the sum of the data signal voltage and threshold voltage of the third switching unit is written into the control terminal of the driving unit, eliminating the effect of threshold voltage changes on light emission, and allowing for a smaller storage capacitor and pixel layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel driving circuit is used, then the circuit structure is simple, but the display uniformity deteriorates due to threshold voltage variations
Solution Approach 1:
The patent applies preliminary action by writing the sum of data signal voltage and threshold voltage into the control terminal of the driving unit before light emission occurs. This advance preparation compensates for threshold voltage variations, ensuring uniform display without requiring complex real-time correction circuits.
Solution Approach 2:
The patent changes the voltage parameter stored in the control terminal from单纯的data signal voltage to the sum of data signal voltage and threshold voltage. This parameter transformation compensates for threshold voltage variations in the driving unit, improving display uniformity while maintaining a relatively simple circuit structure.
2Reliability
If a larger storage capacitor is used, then the threshold voltage compensation is more effective, but the pixel layout area increases
Solution Approach 1:
The patent stores the sum of data signal voltage and threshold voltage in advance in the control terminal before light emission. This preliminary storage eliminates the need for large storage capacitors to maintain threshold voltage compensation during operation, thereby reducing pixel layout area while preserving compensation effectiveness.
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 configuration improves the uniformity of the display image by making the driving current independent of the threshold voltage of the driving unit, resulting in enhanced display resolution and consistency across pixels.
Implementation Method 1
a light emitting device, a storage capacitor, a driving unit and first to fourth switching units
Data Source
AI summary
In the pixel driving circuit of the disclosure, the control terminal of the driving unit is connected with a first terminal of the storage capacitor, the first signal terminal of the first switching unit, the first signal terminal of the second switching unit and the control terminal of the third switching unit. The control terminal of the first switching unit is operable to input a reset signal. The second signal terminal of the first switching unit is connected with an initialization voltage. The control terminal of the second switching unit is operable to input a scan signal. The second signal terminal of the second switching unit is connected with the first signal terminal of the third switching unit. The second signal terminal of the third switching unit is operable to input a data signal. The control terminal of the fourth switching unit is operable to input a light emitting signal.