AMOLED Pixel Circuit with Threshold Voltage Compensation and Fingerprint Sensing
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Solution Overview
Problem
In active matrix organic light-emitting diode (AMOLED) displays, the threshold voltage drift of driving transistors leads to uneven display brightness and image quality issues, and integrating fingerprint identification and touch detection with AMOLED technology poses a challenge.
Innovation Solution
A pixel circuit with a display driving module that compensates for threshold voltage by using a data signal and a second signal source, independent of the driving transistor's threshold voltage, and a fingerprint identification module that detects touch and identifies fingerprints using scanning signals, enabling simultaneous display driving, fingerprint identification, and touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If OLED is driven by current to control light emission, then power consumption is reduced and self luminescence is achieved, but threshold voltage drift of driving TFT causes current change and brightness unevenness
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the OLED light emission phase. The compensation is executed during the initialization stage where the first scanning signal activates the compensation circuitry to measure and correct the driving TFT's threshold voltage drift before the actual display data is written. This ensures that the OLED receives a corrected driving current that accounts for threshold variations, thereby maintaining brightness uniformity across all pixels while preserving the low power consumption benefits of current-driven OLED operation.
2Adaptability or versatility
If fingerprint identification and touch detection are integrated with AMOLED, then system security and functionality are improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the pixel circuit to simultaneously perform display driving, fingerprint identification, and touch detection functions. The same pixel electrode structure serves as both the OLED anode and the capacitive touch sensor electrode. The scanning signal lines are multiplexed to control both display transistor gates and fingerprint sensing circuitry. This universal design allows a single integrated circuit to execute multiple functions without requiring separate dedicated components for each function, thereby improving adaptability while controlling device complexity through shared resources.
3Reliability
If threshold voltage compensation is implemented, then brightness evenness is improved, but circuit complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies merging by combining the threshold voltage compensation circuitry with the existing display driving circuitry within the same pixel structure. The compensation transistors and capacitors are integrated alongside the OLED driving transistors, sharing common signal lines and control mechanisms. The compensation process utilizes the same scanning signal infrastructure already present in the display system, eliminating the need for separate dedicated compensation circuits. This merged approach achieves brightness uniformity improvement while minimizing additional manufacturing complexity by reusing existing circuit elements and processes.
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 improves brightness evenness and image display effect in AMOLED panels while integrating display driving, fingerprint identification, and touch detection, effectively addressing the challenges of threshold voltage drift and multi-functional integration.
Implementation Method 1
a first driving transistor DTFT1, and a fifth TFT T5, wherein the gate electrode of the first driving transistor DTFT1 is connected to the second end of the first storage capacitor C1, a source electrode of the fifth TFT T5 is connected to an anode of a light-emitting diode (LED) 10, and a drain electrode of the fifth TFT T5 is connected to a second signal source Vdd
Data Source
AI summary
The pixel circuit includes a display driving module connected to a first scanning line, a second scanning line, a control line, a data line, a second signal source, a third signal source and an anode of an LED, and configured to, under the control of a first scanning signal, a second scanning signal and a control signal, compensate for a threshold voltage of a driving transistor using a data signal and a second signal, so that a light-emitting driving signal for the LED is irrelevant to the threshold voltage of the driving transistor; and a fingerprint identification module connected to the first scanning line, the second scanning line, a fourth signal source and a signal read line, and configured to, under the control of the first scanning signal and the second scanning signal, identify a fingerprint and detect a touch.