Fingerprint Sensor Memory Reduction via Hadamard Code Selection
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Solution Overview
Problem
Fingerprint sensors face an increase in memory capacity due to the need to store detection signals from all periods corresponding to the number of bits in the code, leading to inefficiencies in data processing and storage.
Innovation Solution
A detecting device with a substrate, detection electrodes, drive electrodes, selection circuits, and a memory that stores output data from selected detection electrodes in a single period, using a Hadamard matrix-based code for efficient selection and scanning of electrodes to reduce memory storage needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If detection signals from all periods corresponding to the number of bits in the code are stored in memory, then complete fingerprint detection data is preserved, but memory capacity increases significantly
Solution Approach 1:
The patent extracts only the necessary detection signals from the complete set of signals that would otherwise be stored. By using the selector to choose specific detection electrodes based on the code, only the minimal required data is stored in memory, separating the essential information from the redundant data.
Solution Approach 2:
Instead of storing all detection signals from every period (excessive action), the system stores only a partial set of signals that are sufficient for fingerprint authentication. The selector enables partial action by choosing specific detection electrodes, achieving the required authentication function with reduced data storage.
2Measurement precision
If all detection electrodes are scanned in every period, then complete detection coverage is achieved, but data processing load increases
Solution Approach 1:
The system extracts and processes only the detection signals from the selected detection electrodes identified by the code, rather than processing all detection signals from all electrodes in every period. This extraction approach reduces the data processing load while maintaining detection precision for the relevant electrodes.
Solution Approach 2:
The patent implements partial action by scanning and processing only a subset of detection electrodes determined by the selector and code, rather than performing exhaustive scanning of all detection electrodes in every period. This partial processing maintains sufficient detection coverage for authentication while improving processing efficiency.
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 approach reduces the memory capacity requirements by storing only the necessary detection signals, thereby minimizing data processing load and memory storage needs, while maintaining effective fingerprint detection and authentication.
Implementation Method 1
Fingerprint sensors detect the shape of a fingerprint of a finger in contact with a detection surface by detecting a change in capacitance due to recesses and protrusions of the fingerprint
Data Source
AI summary
A detecting device includes a substrate, a plurality of detection electrodes provided on the substrate and arrayed in a first direction parallel to the substrate, a plurality of drive electrodes provided on the substrate and arrayed in a second direction intersecting the first direction, a second selection circuit configured to select a plurality of the detection electrodes based on selection signals, a first selection circuit configured to select a plurality of the drive electrodes, a detector coupled to the selected detection electrodes out of the detection electrodes, and a memory storing therein, as a set of output data, a plurality of detection signals output from the selected detection electrodes via the detector by the first selection circuit scanning the drive electrodes in one period when the second selection circuit selects the detection electrodes.