Optical Fingerprint Sensor Layout for Living Body Detection
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Solution Overview
Problem
Conventional sensing devices are unable to perform living body fingerprint identification, limiting the capability for anti-counterfeiting authentication.
Innovation Solution
A sensing device with a circuit structure that includes separate circuits for fingerprint and living body identification, utilizing photodetectors with increased area and wavelength selective layers to enhance living body detection, and a light source for biometric authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical fingerprint identification technology is used, then fingerprint identification can be performed, but living body identification cannot be performed
Solution Approach 1:
The sensing device is divided into separate functional modules: a first circuit for fingerprint identification and a second circuit for living body identification. This segmentation allows each circuit to be optimized for its specific function while working together to provide comprehensive authentication, resolving the contradiction between adding living body identification capability and increasing device complexity.
Solution Approach 2:
The sensing device is designed to perform multiple functions using integrated components. The same substrate and photodetectors are used for both fingerprint identification and living body identification, allowing the device to achieve multi-functionality without proportionally increasing complexity. The circuit structure is configured to handle both authentication types through different signal processing paths.
2Measurement precision
If photodetector area is increased to enhance living body detection sensitivity, then detection accuracy improves, but device area increases
Solution Approach 1:
Different regions of the photodetector are optimized for different functions. The photodetector structure is designed with specific area allocations where certain regions are optimized for fingerprint detection while other regions enhance living body detection sensitivity. This local quality optimization allows enhanced sensitivity without requiring a proportional increase in total photodetector area.
Solution Approach 2:
The patent enhances detection sensitivity by adding vertical dimensionality through multiple layers including the substrate, circuit layers, and photodetector layers. Instead of simply increasing photodetector area in the horizontal plane, the design utilizes stacked layers to increase the effective sensing volume and sensitivity for living body detection while maintaining a compact footprint.
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
Enables accurate living body identification and anti-counterfeiting by enhancing the sensitivity and accuracy of fingerprint and living body detection.
Implementation Method 1
a photodetector disposed on the circuit and electrically connected to the circuit
Implementation Method 2
utilizing photodetectors with increased area and wavelength selective layers to enhance living body detection
Data Source
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AI summary
A sensing device includes a substrate, a first circuit, a second circuit, a first photodetector, and a second photodetector. The substrate has a sensing region. The first circuit is disposed on the substrate and in the sensing region, and configured to sense a fingerprint. The second circuit is disposed on the substrate and in the sensing region, and configured to sense a living body. The first photodetector is electrically connected to the first circuit. The second photodetector is electrically connected to the second circuit. The area of the second photodetector is larger than the area of the first photodetector.