Fingerprint Sensor Integrated with Touch Screen via Transparent Substrates
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Solution Overview
Problem
Capacitive fingerprint sensors face challenges with increased size and cost due to the integration of high-resolution sensor arrays and ICs, leading to reduced touch sensitivity and accuracy in fingerprint recognition, especially when embedded in small devices like smartphones.
Innovation Solution
A display device with a sensor screen that incorporates a fingerprint sensor between two transparent substrates, allowing for closer finger touch positioning and increased recognition accuracy, while also using common electrodes for both touch and fingerprint sensing, thereby enhancing multi-functionality and reducing mutual capacitance interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive fingerprint sensor is integrated with high-resolution sensor arrays and ICs, then fingerprint recognition capability is improved, but device size increases and touch sensitivity decreases
Solution Approach 1:
The patent combines the fingerprint sensor array with the touch sensor array into a single integrated sensor screen. The fingerprint sensor uses the same transparent substrate and electrode structure as the touch sensor, allowing both functions to share the same physical space and component layers, thereby avoiding increased device size while maintaining high-resolution fingerprint recognition capability
Solution Approach 2:
The sensor screen is designed to perform multiple functions simultaneously: it serves as both a touch-sensitive display and a fingerprint recognition sensor. The same transparent electrodes and substrate structure enable both touch detection and fingerprint pattern recognition, eliminating the need for separate dedicated fingerprint sensor components that would increase device size
2Measurement precision
If a capacitive fingerprint sensor is integrated with high-resolution sensor arrays and ICs, then fingerprint recognition capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the fingerprint sensor manufacturing process with the existing touch sensor manufacturing process. Both sensors use the same transparent substrate, electrode materials (such as ITO), and fabrication techniques, allowing for simultaneous production of both sensor types on the same display panel without requiring separate production lines or additional expensive materials
Solution Approach 2:
The sensor screen structure is designed to be universal, serving both touch and fingerprint functions with a single integrated system. This multi-functionality reduces the need for additional separate components and assembly steps, thereby lowering overall manufacturing costs despite the high-resolution fingerprint recognition capability
3Measurement precision
If the fingerprint sensor is positioned closer to the touch point, then fingerprint recognition accuracy is improved, but the display panel becomes more vulnerable to external impacts
Solution Approach 1:
The patent employs a composite structure consisting of multiple transparent substrates with different properties. The first transparent substrate (cover glass) provides mechanical strength and protection against external impacts, while the second transparent substrate (sensor substrate) is positioned closer to the touch point to enable high-accuracy fingerprint recognition. This composite arrangement allows the sensor to be close to the fingerprint while the protective substrate shields against damage
Solution Approach 2:
The sensor screen is divided into multiple functional layers: a protective outer substrate that absorbs external impacts and a sensor substrate positioned closer to the touch surface for accurate fingerprint detection. This segmentation allows each layer to perform its specific function optimally - the protective layer handles mechanical stress while the sensor layer handles precise fingerprint recognition
4Adaptability or versatility
If common electrodes are used for both touch and fingerprint sensing, then multi-functionality is enhanced, but mutual capacitance interference increases
Solution Approach 1:
The patent implements time-division multiplexing where the sensor alternates between touch sensing mode and fingerprint sensing mode. During touch sensing, the system detects touch coordinates using the capacitive electrodes. During fingerprint sensing, the system measures capacitance changes at each electrode to reconstruct the fingerprint pattern. This periodic switching between functions allows common electrodes to serve both purposes while minimizing mutual interference through temporal separation
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 increases fingerprint recognition rate and accuracy, protects the display panel from external impacts, and maintains touch sensitivity by positioning the fingerprint sensor closer to the touch point and using transparent substrates for enhanced rigidity and adhesion.
Implementation Method 1
The capacitive fingerprint sensor utilizes a difference of electric charges charged between ridges and valleys of the fingerprint contacted thereto
Implementation Method 2
positioning the fingerprint sensor closer to the touch point and using transparent substrates for enhanced rigidity and adhesion
Data Source
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AI summary
A display device including a sensor screen (SS) having a touch recognition function and a fingerprint recognition function is disclosed. The display device includes a display panel (DP) having a first display area (DA1) and a second display area (DA2) that are adjacent to each other, a first touch sensor (MTS) being disposed in the first display area, and a sensor screen (SS) having a first transparent substrate (G1) and a second transparent substrate (G2) that are sequentially disposed on the display panel (DP), and a fingerprint sensor and a second touch sensor (FTS) that are disposed between the first transparent substrate and the second transparent of the sensor screen corresponding to the second display area of the display panel.