Fingerprint Sensor Discontinuous Grid Shielding Electric Interference
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Solution Overview
Problem
Fingerprint sensors face challenges in reinforcing the electric field and preventing electric interference between adjacent electrodes, which affects the accuracy and efficiency of fingerprint recognition.
Innovation Solution
A fingerprint sensor design featuring a plurality of sensor electrodes on a substrate with a passivation layer, an insulating layer, and a discontinuous grid made of conductive material that surrounds the insulating layer and is electrically insulated from the electrodes, enhancing the electric field focus and shielding interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If sensor electrodes are arranged closely to increase sensing area, then fingerprint recognition coverage is improved, but electric interference between adjacent electrodes increases
Solution Approach 1:
A discontinuous grid structure is introduced as an intermediary element between adjacent sensor electrodes. This grid, formed by conductive material patterns on the insulating layer, acts as a shielding mechanism that blocks electric field interference between neighboring electrodes while allowing the electrodes to be arranged closely for increased sensing area.
Solution Approach 2:
The continuous insulating layer is segmented into regions by the discontinuous grid pattern. This segmentation creates isolated electric field zones around each sensor electrode, preventing cross-talk between adjacent electrodes while maintaining close spacing for comprehensive fingerprint coverage.
2Measurement precision
If electric field strength is increased to improve detection sensitivity, then fingerprint recognition accuracy is improved, but electric interference between adjacent electrodes worsens
Solution Approach 1:
The discontinuous grid serves as a shielding intermediary that allows strong electric fields to be generated at each sensor electrode for high detection sensitivity, while simultaneously blocking the spread of these fields to adjacent electrodes, thus preventing interference.
Solution Approach 2:
The electric field strength is optimized locally at each sensor electrode position for maximum detection sensitivity, while the discontinuous grid ensures that these strong local fields do not interfere with neighboring electrodes, achieving both high sensitivity and low interference.
3Object-affected harmful factors
If shielding structures are added to prevent electric interference, then electric interference is reduced, but device complexity increases
Solution Approach 1:
The shielding function is merged with the existing insulating layer by forming the discontinuous grid pattern directly on top of it. This integration combines the insulation and shielding functions into a single structural layer, reducing overall device complexity compared to adding separate shielding components.
Solution Approach 2:
The insulating layer serves multiple functions: electrical insulation between the sensor electrodes and the discontinuous grid, and electric field shielding through the grid pattern. This multi-functionality eliminates the need for separate shielding structures, simplifying the device design.
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 design significantly increases the capacitance difference between ridge and valley regions, improving fingerprint recognition accuracy and efficiency by reinforcing the electric field and preventing interference.
Implementation Method 1
a capacitance type fingerprint sensor detects a fingerprint of an examinee by using a capacitance difference in fingerprint regions of the examinee
Implementation Method 2
a discontinuous grid formed of a conductive material, arranged to surround each of regions of the insulating layer on the plurality of sensor electrodes, and electrically insulated from the plurality of sensor electrodes
Data Source
AI summary
A fingerprint sensor for reinforcing an electric field and preventing electric interference between adjacent electrodes. The fingerprint sensor includes a plurality of sensor electrodes provided on a substrate, an insulating layer, and a discontinuous grid formed in the insulating layer. The discontinuous grid includes a plurality of walls that are arranged in a two-dimensional (2D) manner. The plurality of walls are electrically insulated from each other.