Touch-Fingerprint Sensor Electrode Layout for Noise and Linearity
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Solution Overview
Problem
Current touch-fingerprint complex sensors face challenges in achieving improved sensing performance and linearity for both touch and fingerprint recognition, particularly in integrated sensors used in mobile devices and other electronic apparatuses, where external noise and electrode intersection issues affect detection accuracy.
Innovation Solution
The proposed solution involves a touch-fingerprint complex sensor design with a circular or oval configuration, where first and second electrodes are arranged in a distributed uniform pattern with sub-electrodes connected through vias, reducing noise and improving linearity by applying a fixed bias voltage to sub-electrodes during touch detection and using them as dummy electrodes during fingerprint recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a distributed uniform pattern of first and second electrodes is used for touch detection, then touch linearity is improved, but the number of electrodes and circuit complexity increases
Solution Approach 1:
The electrode array is divided into multiple unit groups, with each unit group containing a specific number of first and second electrodes. This segmentation allows the complex electrode system to be managed in modular units, improving touch linearity through uniform distribution while reducing overall circuit complexity through repetitive modular structures.
Solution Approach 2:
Different regions of the electrode array are configured with specific patterns of first and second electrodes tailored to local requirements. The distributed uniform pattern is applied where touch linearity is critical, while other regions may have simplified configurations, optimizing the balance between measurement precision and device complexity.
2Reliability
If sub-electrodes are connected through vias and used as dummy electrodes during fingerprint recognition, then noise is reduced, but manufacturing complexity increases
Solution Approach 1:
The sub-electrodes serve multiple functions: they act as dummy electrodes during fingerprint recognition to reduce noise, and are integrated into the touch detection electrode structure. This multi-functionality reduces noise improvement while avoiding the need for separate noise-reduction components that would increase manufacturing complexity.
Solution Approach 2:
The sub-electrodes are nested within the existing electrode structure and connected through vias to the main electrode layers. This nesting approach allows noise reduction functionality to be embedded within the existing manufacturing process without requiring additional external components or complex assembly steps.
3Measurement precision
If a circular or oval configuration is used for the sensor, then touch sensitivity is improved, but the peripheral region size increases
Solution Approach 1:
The sensor adopts a circular or oval configuration instead of a rectangular shape. This curved geometry improves touch sensitivity by providing more uniform electrode distribution and better capacitive coupling across the sensing surface. The peripheral region is optimized to minimize size while maintaining the beneficial curved geometry, balancing sensitivity improvement with space constraints.
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 design enhances touch linearity and sensitivity while reducing noise and electrode intersection effects, leading to improved detection performance and cost-effectiveness by minimizing the size of the peripheral region and simplifying the circuit configuration.
Implementation Method 1
a plurality of first electrodes 100 extending in a first direction, for example, an X-axis direction, and a plurality of second electrodes 200 extending in a second direction, for example, a Y-axis direction, respectively intersecting the plurality of first electrodes 100
Implementation Method 2
improving linearity by applying a fixed bias voltage to sub-electrodes during touch detection
Data Source
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AI summary
Provided are touch-fingerprint complex sensors, operating methods thereof, and electronic apparatuses including the touch-fingerprint complex sensors. A touch-fingerprint complex sensor may include a plurality of first electrodes extending in a first direction in a touch pad, and a plurality of second electrodes extending in a second direction intersecting the first direction. The plurality of first electrodes may include a plurality of first touch electrodes disposed at regular intervals and a plurality of first sub-electrodes between adjacent ones of the plurality of first touch electrodes. The plurality of second electrodes may include a plurality of second touch electrodes disposed at regular intervals and a plurality of second sub-electrodes between adjacent ones of the plurality of second touch electrodes. The plurality of first touch electrodes may include a first unit group including electrodes, and at least one of the plurality of first sub-electrodes may be disposed between adjacent ones of the electrodes of the first unit group.