AMOLED Pixel Circuit with Optical Touch Sensing
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Solution Overview
Problem
In AMOLED displays, the nonuniform threshold voltages of drive transistors in pixel driving circuits lead to varying electric currents through OLEDs, affecting display performance due to manufacturing processes and device aging, and existing touch technologies are limited by module size and sensitivity compared to capacitive touch.
Innovation Solution
A pixel circuit integrating an optical sensing circuit and a pixel driving circuit, using P-type TFTs for efficient integration and stable current control, with a photosensing transistor and capacitors to sense and convert optical signals into electric signals, allowing for touch detection and uniform light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If drive transistors are used in pixel driving circuits, then light emission control is enabled, but nonuniform threshold voltages cause varying electric currents affecting display uniformity
Solution Approach 1:
The patent implements a feedback mechanism by introducing a sensing transistor that detects the actual current flowing through the OLED and feeds this information back to a compensation circuit. The compensation circuit adjusts the drive signal to compensate for threshold voltage variations, ensuring uniform current distribution across all pixels despite transistor parameter variations.
Solution Approach 2:
The patent changes the operating parameters of the drive transistor by introducing a compensation voltage that dynamically adjusts the gate-source voltage to counteract threshold voltage shifts. This parameter adjustment ensures that the drive transistor operates at the desired current level despite manufacturing variations and aging effects.
2Measurement precision
If capacitive touch technology is used, then touch detection is enabled, but module size and sensitivity are limited
Solution Approach 1:
The patent replaces the capacitive sensing mechanism with an optical sensing mechanism using a photosensing transistor. Instead of detecting changes in electrical capacitance, the system detects changes in optical properties (light absorption or reflection) caused by touch, thereby achieving higher sensitivity without being constrained by module size.
Solution Approach 2:
The photosensing transistor serves multiple functions: it acts as both a touch sensor and a component in the pixel driving circuit. This multi-functionality allows the same structure to enable both display and touch sensing capabilities, eliminating the need for separate touch sensor layers and reducing overall module size while maintaining high sensitivity.
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
The solution ensures stable current-driven OLED emission, prolongs OLED service life, and provides equivalent touch sensitivity without size limitations, enhancing display uniformity and touch functionality.
Implementation Method 1
The photoelectric sensor is configured to sense the optical signal and convert the sensed optical signal into the electric signal
Data Source
AI summary
The present disclosure provides a pixel circuit and a drive method thereof, and a touch display apparatus. The pixel circuit includes a pixel driving circuit, an optical sensing circuit, and a light-emitting element. The pixel driving circuit is configured to drive the light-emitting element to emit light, based on a first control signal from a first control line, a second control signal from a second control line, a scanning signal from a scanning line, and a data signal from a data line. The optical sensing circuit is configured to sense an optical signal, convert the sensed optical signal into an electric signal, and output the electric signal via a reading line based on the first control signal, the second control signal, the scanning signal, and the data signal.