Fingerprint Sensor Image Restoration via Phase Correction
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Solution Overview
Problem
Fingerprint sensors in display devices with multi-layer structures face challenges in accurately restoring fingerprint images due to phase information loss and interference from various ultrasound transmission paths.
Innovation Solution
A method and apparatus that capture a fake fingerprint image, calculate its phase, and apply this phase information to target fingerprint images acquired at different measurement times, thereby synthesizing a final fingerprint image by restoring the magnitude information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fingerprint sensor is disposed under a display panel in a multi-layer structure, then the device can provide both display and fingerprint authentication functions, but the phase information of the fingerprint image is lost due to interference from various ultrasound transmission paths
Solution Approach 1:
The system performs preliminary action by capturing a reference fingerprint image before capturing target fingerprint images. This reference image is used to calculate phase information in advance, which is then applied to correct the target images. This preliminary calculation of phase information from a reference image resolves the phase information loss problem while maintaining the multi-layer structure's versatility.
Solution Approach 2:
A fake fingerprint image is introduced as an intermediary element. This fake fingerprint is placed on the display panel surface and captured by the sensor. The phase information extracted from this intermediary fake fingerprint image serves as a reference to correct the phase shifts in actual fingerprint images, thereby resolving the information loss caused by the multi-layer structure's interference.
2Device complexity
If multiple layers are disposed between the display panel and fingerprint sensor, then the device structure is more integrated, but the accuracy of fingerprint image restoration is reduced
Solution Approach 1:
The system creates a copy of the fingerprint imaging conditions using a fake fingerprint image. This fake fingerprint replicates the optical and acoustic path through the multi-layer structure without containing actual biometric information. By analyzing this copy, the system calculates phase correction data that can be applied to restore accuracy in real fingerprint images while maintaining the integrated multi-layer structure.
Solution Approach 2:
The system changes the parameter being measured by using phase information from a fake fingerprint as a reference. Instead of directly measuring the fingerprint image quality degraded by the multi-layer structure, the system measures phase shifts using a controlled fake fingerprint, then applies this parameter transformation to correct the actual fingerprint images, thereby restoring measurement precision.
3Measurement precision
If phase information is calculated from a fake fingerprint image and applied to target fingerprint images, then fingerprint recognition accuracy is improved, but additional processing time is required
Solution Approach 1:
The phase information calculation is performed as a preliminary action using a fake fingerprint image before actual fingerprint recognition occurs. This reference phase data is computed in advance and stored, so that when real fingerprints are captured, the correction can be applied quickly using pre-calculated parameters, thereby reducing the time loss during actual authentication while maintaining high accuracy.
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 effectively corrects phase shifts caused by the device structure, leading to improved accuracy in restoring fingerprint images and enhancing fingerprint recognition capabilities.
Implementation Method 1
The fingerprint sensor may be implemented by using an optical scanner, an ultrasonic scanner, and/or a capacitive scanner
Implementation Method 2
an incident signal transmitted from the fingerprint sensor is reflected off a user's fingerprint and is received back to the fingerprint sensor as a reflected signal
Data Source
AI summary
A method for restoring an image of a fingerprint sensor is described. The method includes capturing, by the fingerprint sensor, a fake fingerprint image from a fake fingerprint; calculating a phase of the fake fingerprint from the fake fingerprint image; capturing a plurality of target fingerprint images at measurement times by a fingerprint sensor disposed on a rear side of a display panel; applying the calculated phase to each of the acquired target fingerprint images; and combining information from each of the plurality of target fingerprint images to generate a final fingerprint image.