Follow Focus Interference Rings for Compact Clamping

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Solution Overview

Problem

Existing follow focus devices are bulky due to the need for sufficient clamping force and often have difficult-to-operate thumb lever screws, limiting convenience and flexibility, especially when adjusting the rotatable arm position with the device already attached to the camera.

Innovation Solution

The follow focus design incorporates two interference rings with threaded surfaces and keyways, allowing for a high clamping force per unit length and reduced length, along with ball bearings for low-friction rotation and a separate axial securing mechanism, enabling easier operation and adjustment of the rotatable arm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If traditional thumb lever screws are used to secure the rotatable arm, then the clamping force is sufficient, but the device becomes bulky and difficult to operate

Engineering Contradiction:

Improveclamping forceVSAvoidease of adjusting rotatable arm

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

The clamping mechanism is segmented into two independent threaded rings (first interference ring and second interference ring) that can be adjusted separately. This allows the rotatable arm to be positioned and secured in two stages: first positioning the arm axially along the carrier rods, then securing it rotationally. This segmentation eliminates the need for bulky thumb lever screws while maintaining sufficient clamping force.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The traditional thumb lever screw mechanism is extracted and replaced with a more compact threaded ring system. The threaded rings integrate the clamping function directly into the mounting structure, removing the need for separate lever screws and reducing overall device bulk while improving operability.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If traditional clamping mechanisms are used to secure the rotatable arm, then the connection is reliable, but the device length increases

Engineering Contradiction:

Improveconnection reliabilityVSAvoidfollow focus length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The first and second threaded rings are nested within the compact mounting structure of the follow focus device. The rings are positioned within the existing housing and clamp structure, utilizing the available internal space efficiently. This nesting approach maintains reliable threaded connections without extending the overall device length.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Force

If sufficient clamping force is achieved through traditional means, then the rotatable arm is securely fixed, but the clamping length increases device bulk

Engineering Contradiction:

Improveclamping forceVSAvoidfollow focus volume

Core Design Contradiction:

ForceVSVolume of moving object

Solution Approach 1:

The threaded rings concentrate the clamping force application to specific localized contact points on the rotatable arm. Rather than distributing clamping over a long distance, the threaded rings apply focused radial forces at precise locations, achieving secure fixation with minimal clamping length and reduced device volume.

Inventive Principle:

Principle #3Local quality

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 enhances user convenience by providing a more compact and easily operable follow focus with improved clamping force and reduced friction, allowing for precise and flexible adjustment of the rotatable arm without the need for extensive clamping.

Implementation Method 1

along with ball bearings for low-friction rotation

Methodology Applied

Scientific EffectBall bearing: Ball Bearing

Implementation Method 2

two interference rings with threaded surfaces

Methodology Applied

Scientific EffectThreaded mechanism: Screw

Data Source

PatentUS10649171B2Follow focus

Publication Date: 2020.05.12 SUBRATIE ANDREW

AI summary

A follow focus, comprising a main bridge including a transmission housing and an output gear, a removable arm including an input gear and a lens turning gear or an interface capable of receiving a lens gear, an axial securement means that is operable by hand to engage to prevent axial movement between the arm and the transmission housing, and disengages to allow the arm to be rotated and/or removed, such that between the arm and the main bridge there is provided a first engagement element having a substantially axial face having projections and a second engagement element substantially axial face having corresponding indentations, wherein either the first or the second engagement element has a threaded outer circumference and may be fixably rotated, and wherein the first engagement element is borne by the arm, and the second engagement element is borne on the transmission housing such that the axial securement means may be operated to secure the arm to the main bridge so that the projections and corresponding indentations of the first and second engagement elements engage to prevent rotational movement of the arm relative to the transmission housing.