Pixel Driving Circuit Touch Compensation for OLED Luminance Stability
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Solution Overview
Problem
Existing OLED display devices face issues with luminance variation due to touch drive signals affecting the electric current flowing through the OLED, which impacts light emission display when the cathode is reused as a touch electrode.
Innovation Solution
A display device with a pixel driving circuit array that includes a driving unit, data voltage write unit, energy storage unit, threshold compensation unit, and touch driving compensation unit, where the touch driving compensation unit adjusts the voltage of the second energy storage end to maintain a consistent driving current during touch phases, preventing luminance variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cathode of OLED is reused as a touch electrode, then the entire thickness of the display device is reduced, but the voltage variation of the touch drive signal causes electric current flowing through OLED to change, thereby making luminance of the OLED vary with time
Solution Approach 1:
The patent introduces a compensation capacitor connected between the cathode (touch electrode) and a reference potential, which acts as an intermediary element. This capacitor compensates for the voltage variation caused by touch drive signals, thereby stabilizing the electric current flowing through the OLED and preventing luminance variation while maintaining the thin-profile design
2Adaptability or versatility
If a touch drive signal is applied to the cathode for touch detection, then touch function is enabled, but the voltage variation of the touch drive signal causes electric current flowing through OLED to change, thereby affecting light emission display
Solution Approach 1:
The patent converts the harmful voltage variation caused by touch drive signals into a beneficial compensation mechanism. By using a compensation capacitor connected to the cathode, the circuit automatically generates a compensating voltage that counteracts the touch-induced voltage variation, thereby eliminating luminance variation while preserving touch detection functionality
Solution Approach 2:
The compensation capacitor serves as an intermediary element between the touch electrode (cathode) and the reference potential, mediating the voltage variation and converting it into a stable driving condition for the OLED, thus enabling both touch function and stable light emission
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 solution ensures that the driving current generated by the drive transistor does not vary with time during touch phases, thereby maintaining consistent luminance and avoiding any adverse effects on light emission displays.
Implementation Method 1
The capacitor is configured to maintain a voltage difference between the first energy storage end and the second energy storage end when the first energy storage end is floating
Implementation Method 2
A gate electrode of the drive transistor is connected to the first energy storage end, and is configured to generate a driving current for driving an electroluminescent element connected to drain of the drive transistor
Data Source
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AI summary
The present disclosure provides a pixel driving circuit, a display substrate and a driving method thereof, and a display device, wherein the pixel driving circuit comprises: a driving unit, a data voltage write unit, an energy storage unit, a threshold compensation unit and a touch driving compensation unit. The energy storage unit comprises a first energy storage end and a second energy storage end. The touch driving compensation unit is connected to the second energy storage end of the energy storage unit to compensate the voltage of the second energy storage end in a touch phase, so as to maintain that driving current generated by the driving unit does not vary with time. The pixel driving circuit provided by the present disclosure can allow luminance of a driven electroluminescent element does not vary with time in a touch phase, thereby avoiding affecting light emission display of the driven electroluminescent element.