Zoom Lens with Cemented First Unit for Wide Angle and Compact Size

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Solution Overview

Problem

Existing zoom lenses struggle to achieve a balance between small size, wide angle, and effective correction of lateral chromatic aberration, especially in monitoring cameras that require high optical performance across various wavelength ranges.

Innovation Solution

A zoom lens configuration that includes a first lens unit with negative refractive power and a second lens unit with positive refractive power, where the first lens unit consists of two cemented lenses with positive lenses, and the distance between adjacent lens units changes during zooming, satisfying specific refractive index and focal length ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a negative lead type zoom lens with a first lens unit having a negative refractive power and a second lens unit having a positive refractive power is used, then the zoom lens achieves a small size, but it becomes difficult to achieve both small size and wide angle simultaneously

Engineering Contradiction:

Improvesize of zoom lensVSAvoidwide angle capability

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The first lens unit is divided into two cemented lenses, each comprising a positive lens and a negative lens. This segmentation allows for better control of optical parameters while maintaining a compact overall structure, enabling the zoom lens to achieve both small size and wide angle capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each cemented lens in the first lens unit is designed with specific refractive index ratios (ndp1/ndn1 and ndp2/ndn2 within 1.60 to 2.20) and focal length ratios (f1a/f1 and f1b/f1 within 0.30 to 1.80). This local optimization of optical properties enables the lens to achieve wide angle performance while maintaining compact dimensions

Inventive Principle:

Principle #3Local quality

2Volume of moving object

Engineering Contradiction:

Improvesize of zoom lensVSAvoidlateral chromatic aberration correction

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The first lens unit is segmented into two cemented lenses with specifically designed positive and negative lens combinations. This segmentation provides additional degrees of freedom for correcting lateral chromatic aberration across different wavelengths while maintaining a compact lens structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent optimizes specific parameters including the refractive index ratios (ndp1/ndn1 and ndp2/ndn2 within 1.60 to 2.20) and focal length ratios (f1a/f1 and f1b/f1 within 0.30 to 1.80) of the cemented lenses. These parameter optimizations enable effective correction of lateral chromatic aberration in the visible and near-infrared wavelength ranges while keeping the lens compact

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the first lens unit includes two cemented lenses with specific refractive index and focal length ratios, then lateral chromatic aberration is corrected effectively, but the device complexity increases

Engineering Contradiction:

Improvelateral chromatic aberration correctionVSAvoidlens unit structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The first lens unit is divided into two cemented lenses, each with a positive lens and a negative lens. This segmentation enables effective correction of lateral chromatic aberration while the cemented design integrates multiple elements into compact units, balancing optical performance with structural efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Positive and negative lenses are cemented together to form integrated cemented lens units. This merging reduces the number of air-glass interfaces and simplifies the overall structure while maintaining the optical performance needed for lateral chromatic aberration correction

Inventive Principle:

Principle #5Merging (Combining)

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 proposed zoom lens design achieves a small-sized and wide-angle configuration with high optical performance, effectively correcting lateral chromatic aberration across the visible and near-infrared wavelength ranges.

Implementation Method 1

each of the two cemented lenses includes a positive lens... effectively correcting lateral chromatic aberration across the visible and near-infrared wavelength ranges

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

sufficiently correct chromatic aberration from the center to the periphery of images in consideration of wavelengths in a near-infrared wavelength range in addition to the visible wavelength range

Methodology Applied

Scientific EffectChromatic aberration correction: Dispersion (of waves)

Data Source

PatentUS12265206B2Zoom lens and image pickup apparatus

Publication Date: 2025.04.01 CANON KK

AI summary

A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. A distance between adjacent lens units changes during zooming. The first lens unit includes two cemented lenses and each of the two cemented lenses includes a positive lens. Predetermined conditions are satisfied by the zoom lens.