Optical System for Fingerprint Recognition with Aspheric Lenses

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Solution Overview

Problem

Existing optical fingerprint recognition systems lack penetrability, making it difficult to achieve a large field of view, large aperture, and ultra-thin features, which are essential for effective fingerprint recognition in full-screen mobile terminals.

Innovation Solution

The optical system includes a glass screen, an interference screen, a lens group, and a color filter, with specific optical configurations such as f/EPD < 1.8, P/H < 1.5, and 0.5 < ImgH/f < 1.5, utilizing aspheric lenses to enhance light penetration and image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional optical systems are used, then the structure is simple, but the penetrability is poor and cannot achieve large field of view and large aperture

Engineering Contradiction:

ImprovepenetrabilityVSAvoidoptical system structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The optical system is segmented into multiple functional components: glass screen, interference screen, lens group, and color filter. Each component performs a specific function to collectively achieve high penetrability while maintaining a compact structure suitable for full-screen devices.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Aspheric lenses are employed in the lens group to correct optical aberrations and improve image quality. The aspheric surfaces enable better light control and penetration through the glass screen while achieving large field of view and aperture requirements.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Length of moving object

If the optical system is made thinner, then ultra-thin feature is achieved, but light penetration and image quality may deteriorate

Engineering Contradiction:

ImprovethicknessVSAvoidlight penetration

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

Aspheric lenses are used to maximize light gathering efficiency within a thin profile. The curved surfaces optimize light path control, enabling effective fingerprint recognition imaging while maintaining ultra-thin device characteristics.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The optical system parameters are optimized to achieve f/EPD < 1.8 and P/H < 1.5, allowing the system to maintain thin form factor while ensuring sufficient light penetration and image quality for reliable fingerprint recognition.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If large aperture and field of view are achieved, then fingerprint recognition capability is improved, but optical distortion increases

Engineering Contradiction:

Improvefingerprint recognition capabilityVSAvoidoptical distortion

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Aspheric lenses in the lens group effectively correct optical distortions that occur with large aperture and field of view designs. The non-spherical surfaces compensate for aberrations, maintaining high imaging precision for accurate fingerprint recognition.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The optical parameters are carefully controlled within specific ranges (f/EPD < 1.8, P/H < 1.5, 0.5 < ImgH/f < 1.5) to balance large field of view and aperture with minimal distortion, ensuring high fingerprint recognition accuracy.

Inventive Principle:

Principle #35Parameter changes

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

The solution enables a large field of view, larger aperture, and ultra-thin feature, improving fingerprint recognition capabilities in portable electronic devices by optimizing the optical design and using aspheric lenses to minimize distortion and enhance image quality.

Implementation Method 1

a lens group... sequentially from an object side to an image side along an optical axis, may include: an glass screen, an interference screen, a lens group

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

utilizing aspheric lenses to enhance light penetration and image quality... using aspheric lenses to minimize distortion and enhance image quality

Methodology Applied

Scientific EffectAspheric lens correction: Lens

Implementation Method 3

a color filter... sequentially from an object side to an image side along an optical axis, may include: an glass screen, an interference screen, a lens group, and a color filter

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS11614598B2Optical system

Publication Date: 2023.03.28 ZHEJIANG SUNNY OPTICAL CO LTD

AI summary

An optical system, sequentially from an object side to an image side along an optical axis, includes: an glass screen (E1), an interference screen (S3), a lens group, and a color filter (E3). An effective focal length f of the optical system and an entrance pupil diameter EPD of the optical system satisfy f/EPD<1.8. The optical system may be used for fingerprint recognition, and has characteristics such as a large field of view, a larger aperture, and an ultra-thin feature, etc.