Plastic Aspheric Lens System for Compact Imaging

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Solution Overview

Problem

Conventional compact imaging lens systems face challenges in achieving a balance between image quality and total track length, making them unsuitable for portable electronic devices, due to excessive spherical glass lenses and complex manufacturing processes.

Innovation Solution

An image capturing optical system comprising five lens elements with specific refractive powers and aspheric surfaces, including a first lens with positive refractive power, a second with negative refractive power, a third, fourth, and fifth lens elements with aspheric surfaces, where the fifth lens has at least one inflection point, all made of plastic, optimizing the focal length ratio and aberration correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional spherical glass lenses are used to achieve good image quality, then imaging performance is improved, but total track length increases and device compactness deteriorates

Engineering Contradiction:

Improveimage qualityVSAvoidtotal track length

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

The patent changes the material parameter from glass to plastic and the surface geometry from spherical to aspheric. This allows achieving the same aberration correction with a more compact optical path, reducing total track length while maintaining image quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs aspheric surfaces instead of spherical surfaces in the lens elements. The aspheric profiles enable better aberration control with fewer elements and shorter optical path, directly addressing the contradiction between image quality and compactness

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Manufacturing precision

If multiple spherical glass lenses are adhered together to correct chromatic aberration, then chromatic aberration correction is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvechromatic aberration correctionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the material from glass to plastic and uses aspheric surfaces, which can be molded as single pieces. This eliminates the need for complex multi-element adhesion processes while maintaining aberration correction capability through optimized aspheric profiles

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines multiple functions (aberration correction, chromatic correction) into fewer plastic lens elements with aspheric surfaces. This merging reduces the number of separate components and adhesion steps, simplifying manufacturing while achieving the required optical performance

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If five lens elements are used to achieve good image quality, then imaging performance is improved, but total track length becomes excessively long

Engineering Contradiction:

Improveimage qualityVSAvoidtotal track length

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

The patent changes material from glass to plastic and surfaces from spherical to aspheric, enabling stronger refractive power per element. This allows achieving the same imaging performance with reduced optical path length, solving the contradiction between image quality and total track length

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

This configuration reduces the total track length, improves image quality, and enhances the sensitivity and compactness of the system, making it suitable for portable electronic devices while simplifying manufacturing.

Implementation Method 1

a first lens element with positive refractive power having a convex object-side surface; a second lens element; a third lens element; a fourth lens element with both the object-side and image-side surfaces thereof being aspheric

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

both the object-side and image-side surfaces thereof being aspheric, and the fourth lens element is made of plastic

Methodology Applied

Scientific EffectSpherical aberration correction: Lens

Implementation Method 3

a fifth lens element with negative refractive power, both the object-side and image-side surfaces thereof being aspheric, at least one inflection point is formed on at least one of the object-side and image-side surfaces thereof

Methodology Applied

Scientific EffectOff-axis aberration correction: Lens

Data Source

PatentUS8451545B2Image capturing optical system

Publication Date: 2013.05.28 LARGAN PRECISION

AI summary

This invention provides an image capturing optical system in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface; a second lens element; a third lens element; a fourth lens element with both the object-side and image-side surfaces thereof being aspheric, and the fourth lens element is made of plastic; and a fifth lens element with negative refractive power, both the object-side and image-side surfaces thereof being aspheric, at least one inflection point is formed on at least one of the object-side and image-side surfaces thereof, and the fifth lens element is made of plastic. By such arrangement, photosensitivity and total track length of the system can be reduced, and better image quality can be obtained.