Fingerprint Sensor Light Blocking Layer Calibration

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Solution Overview

Problem

Existing fingerprint sensing technologies require large storage space and long loading times for white calibration images, and they take a significant amount of time to perform white calibration on original images acquired through photo sensors due to the inclusion of noise and the need to calibrate the entire sensing region.

Innovation Solution

A fingerprint sensor with a light blocking layer that includes openings, allowing only valid regions of the original calibration image to be used for generating a synthetic calibration image, which is then used for calibration, thereby reducing storage space and calibration time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If white calibration is performed on the entire sensing region, then calibration accuracy is improved, but storage space and loading time increase

Engineering Contradiction:

Improvecalibration accuracyVSAvoidstorage space

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The sensing region is divided into valid regions and invalid regions based on the light blocking layer configuration. Only valid regions are used for white calibration, segmenting the calibration process to exclude unnecessary areas. This reduces the calibration data size while maintaining accuracy in the effective sensing area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Invalid regions from the calibration image are extracted and removed, keeping only the valid regions that correspond to actual fingerprint sensing areas. This extraction process reduces storage requirements while preserving calibration accuracy for the functional regions.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If white calibration is performed on the entire sensing region, then calibration completeness is improved, but calibration time increases

Engineering Contradiction:

Improvecalibration completenessVSAvoidcalibration time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The calibration process is segmented to operate only on valid regions identified through the light blocking layer pattern. This segmentation reduces the total area requiring calibration processing while ensuring complete calibration coverage of the functional sensing regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of calibrating the entire sensing region (excessive action), the method applies calibration only to the necessary valid regions (partial action). This partial calibration approach reduces processing time while maintaining sufficient calibration completeness for fingerprint detection accuracy.

Inventive Principle:

Principle #16Partial or excessive action

3Object-affected harmful factors

If the light blocking layer blocks most light paths, then noise reduction is improved, but the number of valid photo sensors decreases

Engineering Contradiction:

ImprovenoiseVSAvoidnumber of valid photo sensors

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The light blocking layer creates local quality variations across the sensing region, with different areas having different light transmission characteristics. Valid photo sensors are those that receive light through single openings with appropriate optical paths, while other areas are blocked to reduce noise. This local differentiation optimizes the signal-to-noise ratio in valid regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The light blocking layer converts potentially harmful scattered light and noise into beneficial selective filtering. By strategically blocking certain light paths, the system eliminates noise sources while preserving valid fingerprint reflection signals, transforming the blocking function from a limitation into a noise-reduction advantage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 minimizes storage space for white calibration images, decreases the loading time of the calibration image, and reduces the time required for white calibration, improving the efficiency of fingerprint detection.

Implementation Method 1

a light blocking layer on a first surface of the substrate, the light blocking layer including openings in a light blocking mask

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 2

Each photo sensor may receive reflected light generated by a fingerprint of a user

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11488412B2Fingerprint sensing method, fingerprint sensor, and display device including the same

Publication Date: 2022.11.01 SAMSUNG DISPLAY CO LTD

AI summary

A fingerprint sensor includes a substrate, a light blocking layer that is on a first surface of the substrate and includes openings in a light blocking mask, and a sensor layer that is on a second surface of the substrate and includes photo sensors. A fingerprint sensing method of the fingerprint sensor includes: storing a calibration image; generating an original image, based on sensing signals from the photo sensors; performing calibration on the original image by utilizing the calibration image; and detecting a fingerprint, based on the calibrated image. The calibration image is generated by synthetizing valid regions extracted from an original calibration image corresponding to the original image.