Fingerprint Sensor Grid with Conductive Probes
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Solution Overview
Problem
Current fingerprint sensors are cost-prohibitive due to the large number of sensing points required for a two-dimensional array, which makes them unsuitable for many applications, and they are prone to damage and interference from environmental factors.
Innovation Solution
A fingerprint sensor design that incorporates conductive probes extending from a grid of impedance-sensitive electrode pairs through an insulating overlay, allowing for enhanced detection of fingerprint features while protecting the sensor from environmental damage and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-dimensional array of sensing points is used to achieve accurate fingerprint detection, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The sensor is divided into two functional layers: a first array of drive elements and a second array of pickup elements arranged in overlapping关系的网格图案。Each drive element combines with each pickup element to form a virtual sensing point, creating a two-dimensional sensing array through the spatial relationship between elements rather than requiring all sensing points to be physically present simultaneously. This segmentation allows the system to achieve high measurement precision while reducing device complexity.
Solution Approach 2:
The patent transitions from a traditional planar two-dimensional array to a three-dimensional arrangement where drive elements and pickup elements are positioned at different heights (separated by dielectric layers). This vertical dimensionality allows the system to create multiple virtual sensing points through the combination of fewer physical elements, reducing the overall device complexity while maintaining fingerprint detection accuracy.
2Measurement precision
If sensing elements are placed directly at the sensing surface to improve detection accuracy, then measurement precision is improved, but reliability decreases due to exposure to environmental damage and noise
Solution Approach 1:
Conductive probes serve as intermediaries between the protected sensing elements and the fingerprint surface. These probes extend through the dielectric overlay, allowing the drive and pickup elements to sense fingerprint features indirectly through the probes rather than direct contact. This intermediary structure maintains measurement precision while protecting the sensing elements from environmental damage and electrical noise.
Solution Approach 2:
A dielectric overlay (thin film structure) is placed over the sensing elements to protect them from environmental factors. The overlay acts as a protective barrier while the conductive probes penetrate through it, allowing the system to maintain both reliability (through protection) and measurement precision (through probe-mediated sensing).
3Reliability
If conductive probes are added to extend the sensing surface, then reliability is improved by protecting sensing elements, but device complexity increases
Solution Approach 1:
The conductive probes serve multiple functions simultaneously: they extend the sensing surface to contact fingerprint features, provide electrical connection between the drive/pickup elements and the external environment, and act as protective interfaces. This multi-functionality allows the system to improve reliability without proportionally increasing device complexity, as a single structural element accomplishes multiple objectives.
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 sensor provides accurate and reliable fingerprint detection with improved durability and noise resistance, enabling integration into touch-enabled devices without increasing costs.
Implementation Method 1
The drive line is configured to carry a signal that can be coupled to a proximally located object
Implementation Method 2
The pickup line is configured to detect the signal coupled to the object by the drive line
Implementation Method 3
The drive line and the pickup line may be separated by a dielectric layer
Data Source
AI summary
An electronic sensor forms a grid to detect surface features of a proximally located object, such as a fingerprint. The grid includes a plurality of parallel drive lines connectable to a drive source and a plurality of parallel pickup lines oriented substantially perpendicular to the drive lines and overlapping the drive lines. The drive lines are separated from the pickup lines by an insulating dielectric layer. The overlaps where the drive lines and pickup lines cross define impedance-sensitive electrode pairs which act as pixels at which surface features of the proximally located object are detected. One or more conductive probes extend from one or more corresponding impedance-sensitive electrode pairs, through an overlay layer of insulating material, to the sensing surface.