Capacitive Fingerprint Sensor Segmentation for Blur Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fingerprint recognition devices face challenges in accurately sensing fingerprints due to blur phenomena between ridges and valleys, particularly in capacitive sensors, which affect the precise measurement of capacitance, leading to inefficiencies in fingerprint recognition.
Innovation Solution
The proposed fingerprint recognition device employs a sensing panel with multiple sensing blocks, a scan driving unit, and a timing controller that provides sequential initiation signals to scan drivers corresponding to touch inputs, allowing for precise measurement of capacitance through modulated emission and scan clock signals, reducing the blur effect and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensors are used for fingerprint recognition, then the sensing capability is improved, but blur phenomenon occurs between ridges and valleys reducing measurement precision
Solution Approach 1:
The sensing panel is divided into multiple sensing blocks, where each sensing block contains a specific number of sensors (e.g., 5×5 arrangement). This segmentation allows independent control and signal processing for each block, enabling the system to distinguish between actual fingerprint features and blur artifacts by analyzing capacitance variations at the block level.
Solution Approach 2:
The patent employs periodic scanning of sensing blocks through sequential initiation signals from the timing controller. The scan driving unit systematically activates different sensing blocks in a predetermined sequence, allowing the system to collect capacitance data over multiple cycles and distinguish genuine fingerprint patterns from transient blur effects through temporal analysis.
2Measurement precision
If sequential scanning is used to reduce blur effect, then measurement precision is improved, but scanning time increases
Solution Approach 1:
The timing controller activates only specific sensing blocks that contain touch inputs or are relevant to the current scanning phase, rather than sequentially activating all sensing blocks in the entire panel. This partial action approach reduces the total scanning time while maintaining measurement precision by focusing computational resources on relevant regions only.
Solution Approach 2:
The system performs preliminary identification of touch input locations before initiating detailed capacitance measurement. The timing controller uses initial scan results to pre-identify which sensing blocks require detailed analysis, allowing the sequential scanning to be optimized by skipping or reducing scrutiny in non-relevant blocks, thereby reducing overall scanning time.
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 enables precise capacitance measurement and improved fingerprint recognition by minimizing the blur phenomenon, resulting in more accurate fingerprint sensing and reduced noise in capacitive fingerprint recognition systems.
Implementation Method 1
each of the sensors includes a reference capacitor and a sensing capacitor, the sensing capacitor may have a variable capacitance that varies depending on a distance to a fingerprint
Data Source
AI summary
A fingerprint recognition device including: a sensing panel including a plurality of sensing blocks, wherein each of the sensing blocks includes a plurality of sensors; a scan driving unit configured to provide a scan signal to the sensors; and a timing controller configured to provide a second initiation signal to the scan driving unit, wherein each of the sensors includes a reference capacitor and a sensing capacitor, the scan driving unit includes scan drivers that correspond to rows of the sensing blocks, in a fingerprint recognition mode, the timing controller provides the second initiation signal to a scan driver corresponding to a sensing block where a touch input is generated, and in a touch mode, the timing controller sequentially provides the second initiation signal to the scan drivers.