Fixed-Focus Lens Spherical Groups Aberration Control

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Solution Overview

Problem

Conventional fixed-focus lenses used in projection display apparatuses face challenges in achieving good imaging quality with minimal distortion and aberration, high definition, high contrast ratio, and uniform luminance while maintaining a large field of view, due to increased length and cost associated with aspheric lenses.

Innovation Solution

A fixed-focus lens design comprising multiple spherical lens groups with specific refractive powers and configurations, including a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group with a fixed position, allowing for increased field of view and reduced image aberration, while maintaining a compact size and low cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If aspheric lenses are used to modify image aberration, then imaging quality is improved, but manufacturing cost increases and complexity increases

Engineering Contradiction:

Improveimaging qualityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive aspheric lenses with inexpensive spherical lenses that have the same optical function. Specifically, it uses multiple spherical lenses (first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens) arranged in specific groups to achieve the same image quality correction without the high manufacturing cost of aspheric lenses.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent divides the lens system into multiple lens groups (first lens group with first, second, and third lenses; second lens group with fourth, fifth, and sixth lenses; third lens group with seventh lens), where each group performs specific optical functions. This segmentation allows complex aberration correction to be achieved through multiple simple spherical lenses rather than a single complex aspheric lens.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If the main light ray near the reduced side is made substantially parallel to the optical axis, then light source utilization is enhanced, but lens length and size increase

Engineering Contradiction:

Improvelight source utilizationVSAvoidlens length

Core Design Contradiction:

Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent achieves telecentric characteristics (main light ray parallel to optical axis) through careful arrangement of lenses in multiple groups along the optical axis, utilizing the spatial distribution of lens elements to correct ray angles without increasing overall lens length. The specific positioning of the seventh lens in the third group is critical for achieving this.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the number of lenses is increased to reduce distortion and image aberration, then imaging quality is improved, but device complexity increases

Engineering Contradiction:

Improveimaging qualityVSAvoidnumber of lenses

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent organizes 7 spherical lenses into 3 functional groups with specific refractive power characteristics. The first lens group (positive refractive power) handles basic focusing, the second lens group (negative refractive power) corrects distortion and aberration, and the third lens group (positive refractive power) ensures telecentric characteristics. This segmented approach achieves high imaging quality while maintaining manageable complexity.

Inventive Principle:

Principle #1Segmentation

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 design achieves good image quality with reduced image aberration and distortion, increased field of view, and lower manufacturing costs by using spherical lenses and optimizing lens group positions and refractive powers, making it suitable for projection display applications.

Implementation Method 1

The first lens group is disposed between an enlarged side and a reduced side and has a positive refractive power. The second lens group is disposed between the first lens group and the reduced side and has a positive refractive power. The third lens group is disposed between the second lens group and the reduced side and has a positive refractive power.

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS7859763B2Fixed-focus lens

Publication Date: 2010.12.28 YOUNG OPTICS

AI summary

A fixed-focus lens includes a first, a second, and a third lens groups arranged in sequence from the enlarged side to the reduced side and having positive refractive powers. The first lens group includes a first, a second, and a third lenses from the enlarged side to the reduced side. The second lens group includes a fourth, a fifth, and a sixth lenses from the enlarged side to the reduced side. The third lens group includes a seventh lens. The lens of the first lens group closest to the enlarged side in the fixed-focus lens has a concave surface. The distance between the lens surface of the second lens group closest to the reduced side and the lens surface of the third lens group closest to the enlarged side is L1. The overall length of the fixed-focus lens is L. The fixed-focus lens satisfies 0.1<L1/L<0.5.