Pixel Circuit Threshold Compensation for AMOLED Touch Displays
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Solution Overview
Problem
The integration of touch signal detection and pixel circuit driving in in-cell touch screens and AMOLED display panels faces challenges in achieving consistent brightness and reliability due to the dependence of driving current on threshold voltage, particularly in larger and thicker display devices.
Innovation Solution
A pixel circuit configuration that includes a driving transistor, a driving control module, and a light-emitting module, with a touch sensing module, which compensates for the threshold voltage of the driving transistor through diode connection and storage capacitor discharging, ensuring consistent driving currents across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external type touch screen is used, then touch detection function is achieved, but cost and thickness of display device increase
Solution Approach 1:
The patent combines the touch detection function and display function into a single integrated structure by implementing in-cell touch technology within the AMOLED display panel, eliminating the need for separate external touch screens while maintaining both functions
Solution Approach 2:
The display panel structure is designed to perform multiple functions simultaneously - serving as both the display medium and the touch sensing layer, thereby achieving multi-functionality in a single component
2Length of stationary object
If in-cell touch screen is integrated with AMOLED display panel, then thickness and weight are reduced, but brightness uniformity and reliability deteriorate due to threshold voltage dependence
Solution Approach 1:
The patent implements preliminary threshold voltage compensation during the initialization phase by connecting the gate and drain of the driving transistor through the switching transistor, establishing a compensated state before normal operation to ensure consistent brightness
Solution Approach 2:
The circuit incorporates feedback mechanisms where the driving transistor's threshold voltage is continuously compensated through the switching transistor and capacitor network, adjusting the gate voltage to maintain stable driving current and brightness uniformity
3Device complexity
If driving current depends on threshold voltage, then circuit design is simplified, but brightness consistency and reliability worsen
Solution Approach 1:
The patent performs preliminary threshold voltage compensation by establishing a diode connection between gate and drain through the switching transistor during initialization, pre-adjusting the gate voltage to account for threshold voltage variations before normal display operation begins
Solution Approach 2:
The circuit uses feedback through the switching transistor and capacitor network to continuously monitor and compensate for threshold voltage changes in the driving transistor, maintaining stable driving current and brightness consistency throughout operation
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 brightness uniformity and reliability by making the driving current independent of the threshold voltage, facilitating a thinner, lighter, and cost-effective display panel with integrated touch and OLED driving capabilities.
Implementation Method 1
a sensing element and a seventh transistor; wherein a first terminal of the sensing element is connected with an input terminal for a first level signal, and a second terminal of the sensing element is connected with a source of the seventh transistor
Implementation Method 2
a third transistor and an organic light-emitting diode; wherein a source of the third transistor is connected with a source of the second transistor, a drain of the driving transistor, a drain of the eighth transistor, respectively
Data Source
AI summary
Embodiments of the present disclosure provide a pixel circuit, a driving method thereof, an organic light-emitting display panel and a display device. The pixel circuit is provided with a touch sensing module, a driving transistor, a driving control module and a light-emitting module. The pixel circuit compensates for a threshold voltage of the driving transistor by a diode connection of the driving transistor and a discharging of a storage capacitor, so that a driving current of the driving transistor is independent of the threshold voltage of the driving transistor, and thus the driving currents of the OLEDs located at different positions on the organic light-emitting display panel are consistent, which can improve a brightness uniformity and a reliability of the display panel.