Smartcard Fingerprint Sensor Module Eliminating Rigid Bezels
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Solution Overview
Problem
Existing fingerprint sensor modules for smartcards require a separate bezel for providing a reference potential, which increases manufacturing costs and complexity, and is not suitable for flexible smartcards.
Innovation Solution
A fingerprint sensor module integrated with a contact plate of the smartcard, where the contact area comprises a finger contact pad to provide a reference potential to the finger during image capture, eliminating the need for a separate bezel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate rigid metal bezel is used to provide reference potential for fingerprint sensing, then the reference potential can be reliably provided, but the manufacturing cost increases and the device cannot be integrated into flexible smartcards
Solution Approach 1:
The patent merges the reference potential provision function with the existing contact plate structure by designating one of the contact pads as a finger contact pad. This eliminates the need for a separate rigid metal bezel, reducing manufacturing complexity while maintaining the ability to provide a stable reference potential for capacitive fingerprint sensing.
Solution Approach 2:
The contact plate, originally designed solely for electrical contact with terminals, is given a dual function by incorporating a finger contact pad that serves both as a terminal contact point and as a reference potential source for fingerprint sensing. This multi-functionality reduces the number of separate components needed.
2Reliability
If a separate rigid metal bezel is used to provide reference potential, then the sensing function is enabled, but the manufacturing cost significantly increases
Solution Approach 1:
The patent combines the reference potential provision function with the existing contact plate structure by designating one of the contact pads as a finger contact pad. This eliminates the need for a separate rigid metal bezel, reducing manufacturing cost while maintaining the ability to provide a stable reference potential for capacitive fingerprint sensing.
Solution Approach 2:
The patent replaces the expensive rigid metal bezel with a simple conductive contact pad that can be manufactured using standard PCB or flexible substrate techniques. This substitution significantly reduces material and manufacturing costs while achieving the same functional outcome of providing a reference potential.
3Reliability
If a rigid metal bezel is used for fingerprint sensing, then the reference potential is stable, but it cannot be easily incorporated into flexible smartcards
Solution Approach 1:
The patent replaces the rigid metal bezel with a flexible conductive contact pad that can be integrated into flexible smartcard substrates. This flexible implementation maintains the ability to provide a stable reference potential while being compatible with flexible card formulations and bending requirements.
Solution Approach 2:
The patent merges the reference potential provision function with the flexible contact plate structure, eliminating the need for rigid components. This integration allows the fingerprint sensing function to work seamlessly with flexible smartcard materials and construction.
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 solution simplifies manufacturing, reduces costs, and allows for a more compact design, while maintaining effective fingerprint sensing capabilities without the need for a rigid bezel.
Implementation Method 1
capacitive sensing is most commonly used... All capacitive fingerprint sensors provide a measure indicative of the capacitance between each of several sensing structures and a finger placed on or moved across the surface of the fingerprint sensor
Data Source
Figure 1~2A
Figure 2B~3A
Figure 3B
AI summary
A fingerprint sensor module (102) for a smartcard (100), the fingerprint sensor module comprising: a first substrate (200); a fingerprint sensing device (202) mounted on a first side (204) of the first substrate, the fingerprint sensing device having a sensing surface (206) facing in a first direction (207) of the fingerprint sensor module; a second substrate (208) arranged on a second side (210) of the first substrate, opposite the first side, the second substrate comprising a contact area (216) having a plurality of terminal contact pads (212) configured to connect the fingerprint sensor module to an external terminal, the terminal contact pads facing a second direction (214) of the fingerprint sensor module, opposite the first direction; and wherein the contact area (216) comprises at least one finger contact pad (220) configured to provide a potential to a finger in contact with the finger contact pad during fingerprint image capture.