Biometric Sensor Module for Smart Card Integration
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Solution Overview
Problem
Fingerprint sensing devices integrated into smart cards face challenges in achieving a small enough thickness and robustness to handle mechanical stress, such as bending, while maintaining reliable electrical connections.
Innovation Solution
A biometric sensor module with a flexible bottom film carrying electrically conductive lines, bent towards a top film, forming a T-shaped structure with thicker wings that can absorb mechanical stress and provide robust electrical connections, allowing the module to be integrated into smart cards more reliably.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fingerprint sensing device is integrated into a smart card, then biometric identification capability is improved, but the device thickness increases and mechanical stress handling capability deteriorates
Solution Approach 1:
The biometric sensor is integrated within a layered structure comprising a substrate, adhesive layer, and cover layer, nesting multiple functional elements within a compact thickness to achieve biometric capability without excessive card thickness increase
Solution Approach 2:
The patent employs flexible adhesive layers and thin film structures to provide the necessary mechanical compliance and electrical connections while maintaining a thin overall profile suitable for smart card integration
2Adaptability or versatility
If a fingerprint sensing device is integrated into a smart card, then biometric identification capability is improved, but mechanical stress handling capability deteriorates
Solution Approach 1:
The flexible adhesive layer acts as a compliant intermediary that absorbs and distributes mechanical stress from card bending, protecting the rigid sensor element and maintaining reliable electrical connections under mechanical stress
Solution Approach 2:
The assembly combines materials with different mechanical properties (rigid sensor, flexible adhesive, protective cover) to create a composite structure that leverages the strengths of each material to handle mechanical stress while maintaining sensor functionality
3Length of moving object
If electrical connections are made in a thin sensor module, then integration into smart card is improved, but connection reliability under mechanical stress deteriorates
Solution Approach 1:
The flexible adhesive layer serves as both a mechanical compliant element and an electrical connection medium, allowing electrical connections to be made through or within the flexible layer, which maintains connection integrity under bending stress due to its flexibility
Data Source
Figure 1A~1B
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AI summary
The present invention relates to a biometric sensor module for detecting a biometric feature of a user, the biometric sensor module comprising: a biometric sensor comprising an array of sensing elements for acquiring sensing signals indicative of a biometric feature of a user, the array of sensing elements arranged facing towards a front side of the biometric sensor. Further, the biometric sensor module comprises a bottom flexible film attached to a back side, opposite the front side, of the biometric sensor. The bottom flexible film carrying at least one electrically conductive line electrically connectable to the biometric sensor and electrically connectable to an external electrical circuit. The biometric sensor module further comprises a top film attached to the biometric sensor closer to the front side of the biometric sensor than the bottom flexible film. The flexible film includes a bent portion such that the flexible film is bent towards the top film.