Touch Display Panel Fingerprint Sensing via Common Electrode
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Solution Overview
Problem
Conventional touch display panels are unable to recognize fingerprints within the display area, limiting their functionality.
Innovation Solution
A touch display panel design that incorporates a fingerprint identification function, utilizing a substrate with sub-pixels arranged in a matrix, scan and touch lines, thin film transistors, and a driving circuit capable of applying specific voltage and sensing signals to detect fingerprints during designated periods, allowing for simultaneous display, touch sensing, and fingerprint recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional touch display panel structure is used, then display and touch sensing functions are achieved, but fingerprint recognition function cannot be implemented in the display area
Solution Approach 1:
The common electrode is designed to serve multiple functions: it acts as both the common electrode for LCD display operation and the sensing electrode for fingerprint recognition. This multi-functional design allows the display panel to perform display, touch sensing, and fingerprint recognition without adding separate dedicated structures, thereby resolving the contradiction between functionality and complexity
Solution Approach 2:
The patent merges the fingerprint sensing function with the existing display structure by utilizing the common electrode and insulation layer as part of the fingerprint sensing mechanism. The insulation layer between the common electrode and pixel electrode serves dual purposes: electrical insulation for display operation and dielectric layer for fingerprint sensing capacitor formation, thus combining multiple functions into existing components
2Adaptability or versatility
If fingerprint sensing is added to the display area, then fingerprint recognition capability is improved, but the complexity of control and signal management increases
Solution Approach 1:
The driving circuit implements periodic action by allocating specific time periods within each frame cycle for fingerprint sensing operations. During designated periods, the common electrode switches between display voltage mode and fingerprint sensing voltage mode, allowing fingerprint recognition to occur periodically without interfering with continuous display operation, thus managing control complexity through time-division multiplexing
Solution Approach 2:
The common electrode voltage is made dynamic and adjustable, switching between different voltage levels depending on the operational mode (display mode or fingerprint sensing mode). This dynamic voltage control allows the same electrode structure to serve multiple functions, reducing the need for separate dedicated electrodes and simplifying the overall control architecture
3Adaptability or versatility
If fingerprint sensing period is allocated within frame period, then fingerprint recognition is enabled, but display refresh rate may be affected
Solution Approach 1:
Fingerprint sensing is implemented periodically within the frame period by allocating specific time slots for sensing operations. The driving circuit switches the common electrode between display voltage and sensing voltage in a periodic manner, allowing fingerprint recognition to occur during designated periods while maintaining continuous display refresh, thus balancing fingerprint recognition capability with display refresh rate through time-division multiplexing
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
Enables effective fingerprint sensing within the display area, enhancing the panel's functionality and user experience by integrating fingerprint recognition without compromising display and touch sensing capabilities.
Implementation Method 1
a driving circuit 40. The driving circuit 40 is electrically connected to the data lines 24, the touch lines 21, the touch scan lines 22 and the common electrodes 31
Implementation Method 2
During a fingerprint sensing period, the driving circuit 40 applies a fingerprint sensing signal to the common electrode 31 to sense fingerprint
Data Source
AI summary
A display panel able to receive full fingerprint impressions in a display area together with command touches, in addition to showing images, includes a substrate, scan lines, data lines, touch scan lines, touch lines, sub-pixels, and fingerprint sensing units. A method for driving such multifunctional touch display panel is also provided.