Segmented Lead Screw Driven Body with Biasing Arms

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Solution Overview

Problem

Existing lead screw devices for camera lenses face challenges with tooth skipping and thread damage due to external forces, particularly when a photographer interacts with the lens group, as the half nut configuration used to address assembly issues compromises strength and increases the risk of thread damage.

Innovation Solution

A lead screw device with a driven body comprising a pair of driven members that sandwich the lead screw radially, with tooth portions engaging the thread by a biasing force, allowing for stable engagement and movement while absorbing external forces to prevent tooth skipping and thread damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a half nut is used to allow lateral assembly, then ease of manufacture is improved, but strength is reduced leading to tooth skipping and thread damage

Engineering Contradiction:

Improveease of assemblyVSAvoidstrength of nut member

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The single half-nut structure is segmented into two separate driven members that sandwich the lead screw. Each driven member has its own tooth portion that engages with the thread portion, distributing the load and preventing tooth skipping while maintaining ease of assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The biasing mechanism applies localized force to press the tooth portions of both driven members against the thread portion of the lead screw. This creates enhanced contact pressure at the engagement points, preventing disengagement under external forces while maintaining overall structural integrity.

Inventive Principle:

Principle #3Local quality

2Reliability

If the nut member is pressed against the lead screw to prevent tooth skipping, then reliability is improved, but stress concentration damages the thread portions

Engineering Contradiction:

Improveprevention of tooth skippingVSAvoidstrength of thread portions

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The single engagement point is segmented into two separate driven members engaging at different locations on the lead screw. This distributes the stress concentration across multiple engagement points, preventing damage to individual thread portions while maintaining reliable engagement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The biasing mechanism creates a counteracting force that presses the tooth portions against the thread portion, balancing the external forces applied to the lens group. This prevents disengagement and tooth skipping while distributing the load evenly across both driven members.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Stability of the object's composition

If both ends of the lead screw are supported by a U-shaped supporting member, then stability is improved, but ease of assembly is reduced due to assembly order requirements

Engineering Contradiction:

Improvestability of lead screwVSAvoidease of assembly

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The single nut member is segmented into two driven members that can be assembled independently on either side of the lead screw. This eliminates the need for specific assembly sequences and allows the lead screw to be fully supported by the U-shaped member while maintaining ease of assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of assembling the nut member onto the lead screw from one end, the two driven members are assembled by sandwiching the lead screw between them. This inverted assembly approach allows simultaneous support of both ends of the lead screw while simplifying the assembly process.

Inventive Principle:

Principle #13The other way round (Inversion)

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 solution effectively prevents tooth skipping and thread damage by distributing external forces through the biasing mechanism, ensuring stable engagement and accurate lens movement, even under external forces, thus enhancing the reliability and durability of the lens driver.

Implementation Method 1

the driven body includes a biasing member which biases the pair of driven members in a direction sandwiching the lead screw in the radial direction, and a tooth portion provided in each driven member engages with the thread portion of the lead screw by the biasing force

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10473882B2Lead screw device, lens driver, lens barrel, and camera using the lead screw device

Publication Date: 2019.11.12 RICOH IMAGING COMPANY

AI summary

An optical device includes an optical system including a plurality of lens groups, at least one lens group being a movable lens group moving in an optical axis direction, and a movable frame to move the movable lens group. The movable frame includes a driving source, a drive screw, a lens supporting frame, and maintaining an integrated state relative to the movable lens group, a plurality of arms disposed in a position to face the drive screw and being openable and closable relative to the drive screw with a single opening and closing axis as a support axis, the plurality of arms including a first arm and a second arm, and a biasing spring configured to apply a biasing force to the first arm in a direction in which the first arm approaches the drive screw, wherein the lens supporting frame is further configured to support the biasing spring.