AMOLED Pixel Circuit for Full-Screen Fingerprint Recognition
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Solution Overview
Problem
Current AMOLED display screens in mobile phones are limited in their ability to implement effective fingerprint recognition across the entire display area due to complex structures and recognition principles, primarily focusing on glass or separator-related power penetration.
Innovation Solution
An AMOLED and fingerprint recognition-based driving and scanning circuit is developed, comprising an array of units with specific thin film transistors and capacitors that allow for both light emission and fingerprint capacitance formation, enabling fingerprint recognition in any display area by switching between driving and scanning states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fingerprint recognition structure is integrated with AMOLED circuit, then fingerprint recognition capability is improved, but device structure complexity increases
Solution Approach 1:
The patent applies multi-functionality by enabling the AMOLED pixel circuit to perform dual functions: display operation and fingerprint recognition. The pixel circuit includes both AMOLED driving components (first TFT, second TFT, third TFT, OLED) and fingerprint scanning components (fourth TFT, pixel capacitance), allowing the same physical structure to serve multiple purposes through state switching
Solution Approach 2:
The patent merges the fingerprint scanning unit with the AMOLED driving unit into a single integrated pixel circuit. The cathode terminal serves dual roles by connecting to both the OLED through the second and third TFTs for display function, and to the fourth TFT for fingerprint recognition function, combining two separate functions into one unified structure
2Adaptability or versatility
If fingerprint scanning unit is added to cathode terminal, then fingerprint recognition coverage is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by switching the pixel circuit between display state and fingerprint scanning state at different time periods. During display state, the first, second, and third TFTs are on while the fourth TFT is off for OLED operation. During fingerprint scanning state, the first, second, and third TFTs are off while the fourth TFT is on for capacitance formation. This time-division multiplexing allows fingerprint recognition coverage across the entire display area while minimizing power consumption by activating different components only when needed
Solution Approach 2:
The patent applies dynamics by making the circuit state adjustable and switchable between two modes. The pixel circuit dynamically transitions between display operation mode and fingerprint recognition mode based on system requirements, allowing the same hardware to adapt its function and power consumption characteristics according to the current operational state
3Reliability
If one and only one unit is in conducting state, then functional interference is reduced, but control complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the pixel circuit into functionally independent segments: the AMOLED driving unit (first TFT, second TFT, third TFT, OLED) and the fingerprint scanning unit (fourth TFT, pixel capacitance). Each segment can be independently controlled through dedicated control signals (first driving voltage, first switching voltage for display; second driving voltage, second switching voltage for fingerprint recognition), ensuring that only one segment is active at a time to prevent functional interference while maintaining simple control logic
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 enables comprehensive fingerprint recognition and related operations across the entire mobile phone screen, integrating fingerprint scanning capabilities with AMOLED display functions without compromising display performance.
Implementation Method 1
an OLED being positioned between the cathode terminal and the second thin film transistor
Implementation Method 2
a fingerprint scanning unit for forming pixel capacitances
Data Source
AI summary
A driving and scanning circuit, a display screen and a mobile terminal, comprise driving and scanning units which are distributed in an array, each comprising an AMOLED driving unit for driving an OLED to emit light and a fingerprint scanning unit for forming pixel capacitances, wherein the AMOLED driving unit comprises a first thin film transistor, a second thin film transistor, a third thin film transistor and an OLED, the first thin film transistor is connected with a driving voltage and a first switching voltage, the second thin film transistor and the third thin film transistor are respectively connected with an anode terminal and a cathode terminal, and the OLED is positioned between the cathode terminal and the second thin film transistor; the cathode terminal also comprises a fourth thin film transistor connected with a second driving voltage and a second switching voltage.