Capacitive Fingerprint Sensor Grounded Shielding for Signal Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive fingerprint identification devices face signal interference issues due to the increasing number of leads required for higher resolution, which affects the accuracy of fingerprint recognition.
Innovation Solution
The implementation of a capacitive fingerprint identification device with a conductive layer grounded to prevent signal interference, featuring sensor electrodes and leads protected by a contact protection layer and adhesive, and a manufacturing method that includes patterning conductive films and insulating layers to optimize electrode and lead arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of leads is increased to achieve higher resolution fingerprint identification, then the resolution is improved, but signal interference increases
Solution Approach 1:
A ground layer is introduced as an intermediary component between the leads and the substrate. This ground layer acts as a mediator that provides a reference potential and shields the leads from electromagnetic interference, thereby maintaining signal integrity while allowing increased lead density for higher resolution fingerprint sensing.
Solution Approach 2:
The electrical parameters of the lead arrangement are optimized by controlling the spacing, orientation, and potential distribution of leads. By adjusting these parameters and implementing proper grounding, the signal-to-noise ratio is improved, allowing higher resolution without proportionally increasing interference.
2Measurement precision
If more leads are arranged around sensor electrodes for higher resolution, then the sensing capability is improved, but the complexity of the device increases
Solution Approach 1:
The lead structure is segmented into functionally distinct groups: signal leads connected to sensor electrodes, ground leads forming a reference plane, and power leads. This segmentation allows each group to be optimized independently and simplifies the overall design and manufacturing process while maintaining high resolution capability.
3Measurement precision
If the quantity of leads is increased to improve resolution, then the fingerprint identification accuracy is improved, but the reliability of the device decreases due to signal interference
Solution Approach 1:
The ground layer is designed to create an equipotential reference plane beneath the sensor electrodes and leads. By maintaining a constant potential throughout the ground layer, electromagnetic interference between adjacent leads is minimized, ensuring stable and reliable signal transmission across all sensor elements even at high densities.
Data Source
AI summary
A fingerprint identification device includes a fingerprint identification controller and a fingerprint identification sensor. The fingerprint identification sensor includes a substrate having a top surface, a bottom surface opposite to the top surface, and a side surface coupled between the top surface and the bottom surface. Sensor electrodes are arranged on the top surface, electrical leads couple the sensor electrodes and the fingerprint identification controller. The coupling leads extend from the top surface along the side surface to the bottom surface.