Interchangeable Lens Flange-Back Correction for Field Curvature

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Solution Overview

Problem

Existing interchangeable lenses are susceptible to curvature of field errors due to variations in flange back distance, which cannot be effectively corrected, especially in ultra-short focus lenses.

Innovation Solution

The interchangeable lens includes a flange back distance correction lens group that can move along the optical axis to adjust for errors in the flange back distance, combined with a focus lens group to adjust focus and correct curvature of field, allowing for precise attachment to apparatus bodies with varying flange back distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional interchangeable lens is used with fixed lens groups, then the lens structure is simple, but curvature of field error occurs due to flange back distance variation

Engineering Contradiction:

Improvecurvature of field correctionVSAvoidlens group structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the lens groups movable along the optical axis. The first lens group can move to adjust focus at the magnification conjugate point, while the second lens group can move to correct flange back distance errors. This dynamic adjustment capability allows the lens to adapt to different flange back distances and correct optical aberrations, resolving the contradiction between manufacturing precision and device complexity.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the lens is designed for a specific flange back distance, then the optical performance is optimized, but the lens cannot accommodate apparatus bodies with flange back distance errors

Engineering Contradiction:

Improvecompatibility with apparatus bodiesVSAvoidoptical aberration control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The movable lens groups enable the lens to adapt to different flange back distances while maintaining optical performance. The first lens group adjusts focus position, and the second lens group compensates for flange back distance variations, allowing the lens to work with apparatus bodies that have manufacturing tolerances or variations in flange back distance.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the position parameters of the lens groups along the optical axis to accommodate different flange back distances. By adjusting the positions of the first and second lens groups, the lens can compensate for flange back distance errors and maintain proper focus and minimize optical aberrations across different apparatus bodies.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If focus adjustment is made by moving lens groups, then focus can be corrected, but flange back distance errors cause curvature of field

Engineering Contradiction:

Improvefocus adjustmentVSAvoidcurvature of field error

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent segments the lens system into multiple independent movable groups. The first lens group is dedicated to focus adjustment at the magnification conjugate point, while the second lens group is dedicated to flange back distance correction. This segmentation allows each group to perform its specific function independently, correcting focus errors without introducing curvature of field aberrations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second lens group acts as an intermediary element between the first lens group and the image plane. It specifically compensates for flange back distance errors by moving along the optical axis, thereby mediating the harmful effect of curvature of field while allowing the first lens group to handle focus adjustment.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design reduces the impact of flange back distance errors while suppressing curvature of field, ensuring consistent image quality across different apparatus bodies.

Implementation Method 1

a flange back distance correction lens group that can move along an optical axis to correct an error in a flange back distance of the interchangeable lens with respect to the image forming surface

Methodology Applied

Scientific EffectOptical path correction: Lens

Implementation Method 2

a focus lens group that can move along an optical axis to adjust a focus at the magnification conjugate point

Methodology Applied

Scientific EffectFocusing: Focusing

Data Source

PatentEP3933478B1Interchangeable lens, image projection device and imaging device

Publication Date: 2025.08.13 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(c)

AI summary

The present embodiment discloses an interchangeable lens that can be detachably attached to an apparatus body 105 having an image forming surface Q1 on which an image is formed, and the interchangeable lens has a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side. The interchangeable lens includes a focus lens group FG1 that can move along an optical axis to adjust a focus at the magnification conjugate point and a flange back distance correction lens group FBG that can move along the optical axis to correct an error in a flange back distance of the interchangeable lens with respect to the image forming surface Q1.