Under-screen Fingerprint Sensor Using Micro Lens Array

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Solution Overview

Problem

Current under-screen fingerprint identification technologies, such as those based on collimating holes and pinhole imaging, result in larger device sizes and thicknesses, making them unsuitable for electronic devices with size and thickness constraints.

Innovation Solution

An optical image capturing unit comprising an optical converging device with a diaphragm and window, where the optical signal is converged within a specific incident angle range and transmitted to a photosensing unit, allowing for a compact design that reduces the thickness of the fingerprint identification apparatus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an array of collimating holes is used for under-screen fingerprint identification, then fingerprint identification function is achieved, but the device size increases due to requirements for period and aspect ratio of collimating holes

Engineering Contradiction:

Improvefingerprint identification functionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the optical parameters by using a micro lens array with specific focal lengths and aperture sizes, replacing the traditional collimating hole array. The micro lenses have optimized parameters (focal length, aperture diameter) that achieve the same fingerprint identification function with reduced device area.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical collimating hole structure with an optical micro lens array system. This substitution allows for more efficient light control and reduces the required device area while maintaining fingerprint identification functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If pinhole imaging principle is used for under-screen fingerprint identification, then fingerprint detection is achieved, but the apparatus thickness increases requiring a lens module

Engineering Contradiction:

Improvefingerprint detection functionVSAvoidapparatus thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent extracts and eliminates the traditional lens module from the optical path by using a micro lens array integrated directly with the sensor. This removal of the separate lens module significantly reduces the apparatus thickness while maintaining fingerprint detection capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the micro lens array with the sensor structure, integrating multiple functions into a single compact unit. This consolidation eliminates the need for separate lens modules and reduces overall apparatus thickness.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If traditional optical imaging system is used, then image capturing function is achieved, but the system thickness is large and cannot be integrated under thin display screens

Engineering Contradiction:

Improveimage capturing functionVSAvoidsystem thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent transitions from a traditional three-dimensional optical imaging system to a two-dimensional micro lens array configuration integrated directly on the sensor plane. This dimensional change enables thin-profile integration under display screens while maintaining image capturing functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 solution enables a thinner and more compact optical image capturing system suitable for integration under display screens, enhancing biometric identification capabilities without the need for additional space, thus supporting full-screen solutions in electronic devices.

Implementation Method 1

an optical converging device; where the optical converging device is configured to converge an optical signal within a specific incident angle range to the window

Methodology Applied

Scientific EffectOptical convergence: Lens

Implementation Method 2

the optical converging device is configured to converge an optical signal within a specific incident angle range to the window, and the optical signal is transmitted to the photosensing unit via the window

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

a photosensing unit disposed under the diaphragm, where the optical converging device is configured to converge an optical signal within a specific incident angle range to the window, and the optical signal is transmitted to the photosensing unit via the window

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11514709B2Biometric identification device using a light detection apparatus with light blocking layer/diaphragm

Publication Date: 2022.11.29 SHENZHEN GOODIX TECH CO LTD

AI summary

Provided are an optical image capturing unit and an electronic device. The optical image capturing unit includes: an optical converging device; a diaphragm disposed on a back focal plane of the optical converging device, where the diaphragm is provided with a window; and a photosensing unit disposed under the diaphragm, where the optical converging device is configured to converge an optical signal within a specific incident angle range to the window, and the optical signal is transmitted to the photosensing unit via the window.