Lens Rotation Mechanism for Focal Position Correction

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Solution Overview

Problem

Conventional lens adjustment methods fail to accurately correct focal position shifts due to non-uniform lens surface shapes and refractive indices, especially in high-definition television broadcast systems, leading to insufficient correction, particularly at telephoto settings and with heavy focus lens groups.

Innovation Solution

A lens device with a lens moving mechanism and a separate lens rotating mechanism that adjusts focal positions using stored positions and rotation angles, allowing for precise correction of focal shifts caused by non-uniformities in lens surface shapes and refractive indices, with the lens rotating mechanism driven independently from the moving mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a focus lens group is used to correct focus shift, then correction capability is provided, but the weight is heavy and correction speed cannot be increased

Engineering Contradiction:

Improvefocus correction capabilityVSAvoidfocus lens group weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The invention extracts the focus correction function from the heavy focus lens group and implements it through a different mechanism. By using a master lens group with rotation capability, the correction function is separated from the traditional heavy focusing mechanism, achieving correction without the weight penalty of a dedicated focus lens group.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The master lens group is given multiple functions: it serves both as part of the zoom optical system and as the correction mechanism. By rotating the master lens group about the optical axis in addition to moving it along the optical axis, a single component performs both zoom-related and correction-related functions, eliminating the need for separate heavy focus correction lenses.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a master lens group is used for correction, then correction is provided, but the adjustment stroke reaches an upper limit and sufficient correction is not performed at telephoto settings

Engineering Contradiction:

Improvefocus correction functionVSAvoidadjustment stroke

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The invention adds a rotational degree of freedom to the master lens group. Instead of relying solely on linear movement along the optical axis, the lens group can also rotate about the optical axis. This dimensional change provides an additional parameter for correction, enabling sufficient correction range even when linear stroke is limited, particularly at telephoto settings.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If lens surface shape or refractive index is not uniform, then manufacturing is simplified, but adverse effects cannot be eliminated and sufficient correction is not achieved

Engineering Contradiction:

Improvelens uniformityVSAvoidadverse effects from non-uniformity

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention converts the adverse effects of non-uniform lens characteristics into correctable parameters. By introducing rotational adjustment capability, the system can compensate for the optical imperfections caused by non-uniform lens surface shapes or refractive indices. The rotation allows different portions of the non-uniform lens to be positioned optimally, transforming a manufacturing limitation into a correctable condition.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Ease of manufacture

If conventional lens adjustment methods are used, then manufacturing is simple, but performance superior to high-definition television broadcast system cannot be achieved

Engineering Contradiction:

Improveconventional adjustment simplicityVSAvoidfocal position accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The invention transforms the static lens adjustment into a dynamic system. The master lens group can be rotated about the optical axis in addition to moving along it, creating a dynamic adjustment mechanism. This dynamic capability allows precise focal position correction that adapts to different zoom positions and aperture settings, achieving high-definition broadcast system performance while maintaining manufacturing feasibility through a single multi-functional lens group.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10088654B2Lens device and correction method for lens device

Publication Date: 2018.10.02 FUJIFILM CORP

AI summary

This invention provides a lens device and a correction method therefor whereby the focal position of the lens device can be corrected with high accuracy even if a lens surface shape or the like is not uniform. A ring-shaped lens fixing frame 52 is mounted on the outer periphery of a lens 51. A gear 53 is formed on the lens fixing frame 52 in the circumferential direction. A gear 54, which engages with the gear 53, is rotated by a motor 20A. Then, the lens 51 rotates about the optical axis L thereof. Further, a rack 57, which extends in the direction of the optical axis L, is formed on a part of the lens fixing frame 52. A pinion 58 engages with the teeth 57A of the rack 57, and the pinion 58 is rotated by another motor 20B. Then, the rack 57 moves in the direction of the optical axis L, and thus the lens 51 moves in the direction of the optical axis L. Since the lens 51 rotates about the optical axis L thereof, even if the surface shape or the like of the lens 51 is uneven in the circumferential direction, improvement can be realized.