Linear Fingerprint Sensor Reducing Data Bandwidth
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Solution Overview
Problem
Conventional silicon fingerprint sensors are large, expensive, and have high power consumption, making them unsuitable for real-time authentication in consumer electronics due to the need for large memory buffers and high-speed data transmission, which increases costs and restricts their use in applications like portable electronics and personal ID cards.
Innovation Solution
A linear image sensing device with an image matching function that outputs non-overlapped partial fragment images, reducing data size and transmission bandwidth, and utilizing a programmable gain amplifier, analog-to-digital converter, image matching module, and control logic to regenerate non-overlapped images without the need for high-speed microprocessors or large memory buffers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional silicon fingerprint sensors are used to achieve real-time authentication, then authentication speed is improved, but device size and power consumption increase
Solution Approach 1:
The patent divides the sensing process into discrete linear segments that are scanned sequentially. Instead of using a large 2D sensor array, the fingerprint is scanned line by line through a linear sensor array, reducing the number of sensing elements required while maintaining real-time authentication capability
Solution Approach 2:
The patent transitions from a 2D sensor array to a 1D linear sensor array by introducing time as an additional dimension. The fingerprint image is acquired through sequential linear scans over time, converting a spatial problem into a spatio-temporal solution that reduces hardware complexity and power consumption
2Area of stationary object
If conventional silicon fingerprint sensors with large sensing area are used, then complete fingerprint capture is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the fingerprint sensing into multiple sequential linear passes. A small linear sensor array scans across the fingerprint multiple times, capturing the complete image through time-sequential acquisition rather than requiring a large single-area sensor, thereby reducing manufacturing cost
Solution Approach 2:
The patent reuses the same linear sensor array for multiple scanning passes over the fingerprint. Instead of requiring a large sensor that captures the entire fingerprint in one static image, the system discards the need for additional sensor elements and recycles the same sensor through sequential scanning, reducing manufacturing complexity and cost
3Reliability
If overlapped whole fragment images are output for reconstruction, then complete image reconstruction is achieved, but data transmission bandwidth and memory capacity increase
Solution Approach 1:
The patent extracts and removes the redundant overlapped portions from sequential fragment images before transmission. By identifying and eliminating duplicate data regions that would otherwise require transmission and processing, the system maintains complete image reconstruction capability while significantly reducing data transmission bandwidth and memory capacity requirements
Data Source
AI summary
In a linear image sensing device with image matching function, a linear sensors array senses a finger, which is moving over it, to obtain fragment image analog signals, which are amplified, by a programmable gain amplifier, into amplified signals. An analog-to-digital converter sequentially converts the amplified signals into digital image signals. An image matching module sequentially receives and processes adjacent two of the digital image signals, and outputs continuous non-overlapped fragment images through an input/output interface. A control logic controls operations and communications of the above-mentioned components. A terminal system receives the non-overlapped fragment images and assembles the non-overlapped fragment images into a complete fingerprint image in a manner of stacking the images side by side.