Compact Imaging Lens with Aspheric Fifth Element

Solution Overview

Problem

Existing imaging lenses for compact devices struggle to achieve a balance between low-profile design, high brightness, and wide field of view while effectively correcting aberrations, particularly in the peripheral area.

Innovation Solution

The proposed imaging lens configuration includes an aperture stop followed by a positive refractive power first lens, a negative refractive power biconcave second lens, a third lens with positive or negative refractive power and aspheric surfaces, a meniscus double-sided aspheric fourth lens, and a negative refractive power fifth lens with an aspheric image-side surface having a pole-change point, optimized by specific conditional expressions to ensure low-profileness and aberration correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the total track length is reduced to achieve low-profile design, then the device becomes more compact, but aberration correction becomes difficult

Engineering Contradiction:

Improvetotal track lengthVSAvoidaberration correction

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The imaging lens is divided into five distinct lens groups (first through fifth lens groups) with different refractive powers and shapes. Each group is optimized for specific aberration correction functions, allowing the compact system to achieve proper aberration correction despite the reduced total track length.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple lens surfaces including the first lens object-side surface, second lens image-side surface, third lens object-side surface, fourth lens image-side surface, and fifth lens image-side surface are designed with aspheric shapes. These curved surfaces enable effective aberration correction within the compact lens structure by controlling light ray paths more precisely than spherical surfaces would allow.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Illumination intensity

If the F-value is reduced to increase brightness, then the lens gathers more light, but aberration correction becomes more difficult

Engineering Contradiction:

ImprovebrightnessVSAvoidaberration correction

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The lens system is segmented into multiple groups with specific refractive powers: the first lens group has strong positive refractive power for light gathering, while subsequent groups have negative or weak positive refractive powers for aberration correction. This segmentation allows the system to achieve high brightness (F-value of 2.5 or less) while maintaining proper aberration correction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs aspheric surfaces with specific pole-change points and optimized curvature radii (r1, r2, r7, r8) to control aberrations. By carefully adjusting these geometric parameters and the refractive indices of different lens groups, the system achieves both high brightness and effective aberration correction simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If the field of view is increased to provide wider coverage, then the lens captures more scene, but aberration correction in peripheral area becomes difficult

Engineering Contradiction:

Improvefield of viewVSAvoidperipheral aberration correction

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The imaging lens is divided into five distinct lens groups (first through fifth lens groups) with different refractive powers and shapes. Each group is optimized for specific aberration correction functions, allowing the compact system to achieve proper aberration correction despite the reduced total track length.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple lens surfaces including the first lens object-side surface, second lens image-side surface, third lens object-side surface, fourth lens image-side surface, and fifth lens image-side surface are designed with aspheric shapes. These curved surfaces enable effective aberration correction within the compact lens structure by controlling light ray paths more precisely than spherical surfaces would allow.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Length of moving object

If the total track length is reduced to achieve low-profile design, then the device becomes more compact, but the brightness and field of view performance deteriorates

Engineering Contradiction:

Improvetotal track lengthVSAvoidbrightness

Core Design Contradiction:

Length of moving objectVSIllumination intensity

Solution Approach 1:

The imaging lens is divided into five distinct lens groups (first through fifth lens groups) with different refractive powers and shapes. Each group is optimized for specific aberration correction functions, allowing the compact system to achieve proper aberration correction despite the reduced total track length.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple lens surfaces including the first lens object-side surface, second lens image-side surface, third lens object-side surface, fourth lens image-side surface, and fifth lens image-side surface are designed with aspheric shapes. These curved surfaces enable effective aberration correction within the compact lens structure by controlling light ray paths more precisely than spherical surfaces would allow.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 configuration results in a compact imaging lens that provides brightness with an F-value of 2.5 or less and a wide field of view of 70 degrees or more, effectively correcting various aberrations and maintaining low-profileness, suitable for integration in compact devices like smartphones and mobile phones.

Implementation Method 1

an imaging lens which forms an image of an object on a solid-state image sensor... includes, in order from an object side to an image side, an aperture stop; a first lens with positive refractive power... a second lens with negative refractive power... a third lens with positive or negative refractive power... a fourth lens with positive refractive power... and a fifth lens with negative refractive power

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9541739B2Imaging lens

Publication Date: 2017.01.10 TOKYO VISIONARY OPTICS CO LTD

AI summary

A compact, low-profile, low-cost imaging lens with brightness of F-value 2.5 or less and a wide field of view, which corrects aberrations properly. Elements are arranged from an object side: an aperture stop, positive first lens having a convex object-side surface, negative biconcave second lens having concave object-side and image-side surfaces, positive or negative third lens having a convex object-side surface and at least one aspheric surface; positive meniscus double-sided aspheric fourth lens having a convex image-side surface; and negative double-sided aspheric fifth lens having a concave image-side surface. The fifth lens' aspheric image-side surface has a pole-change point off an optical axis, and the imaging lens satisfies the following conditional expressions:TTL/2ih≦0.8 (1)1.60<Nd3<1.70 (2)4.0<|r9/r10|<14.0 (3)whereTTL: total track lengthih: maximum image heightNd3: third lens refractive index at d-rayr9: curvature radius of the fifth lens object-side surfacer10: curvature radius of the fifth lens image-side surface.