Follow Focus Worm Gear Assembly for Zero-Backlash Rotation

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Solution Overview

Problem

Existing follow focus systems suffer from transmission gap errors between the handwheel body and the follow focus gear, leading to inconsistent rotation and potential failure to maintain focus.

Innovation Solution

The proposed follow focus system incorporates an active worm and a driven worm with a 90° angle, where the first worm gear is meshed with the second worm gear, eliminating the transmission gap and ensuring synchronized rotation between the handwheel body and the follow focus gear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If 45° bevel gear is used to rotate by 90°, then the transmission structure can change rotation direction, but there is a transmission gap error of 1°-3° leading to inconsistent rotation

Engineering Contradiction:

Improverotation direction controlVSAvoidtransmission accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the traditional 45° bevel gear mechanical transmission system with a worm gear mechanism. The worm gear's unique engagement geometry eliminates the transmission gap inherent in bevel gears, achieving precise 90° rotation direction change without the 1°-3° error that plagues conventional systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental transmission parameters by using a worm gear with specific helix angle and engagement characteristics. This parameter change transforms the transmission mechanism from one with inherent gaps (bevel gear) to one with continuous contact and zero backlash (worm gear), thereby eliminating the transmission accuracy problem.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If transmission gap exists in the gear system, then the structure is simpler, but the follow focus gear cannot follow the handwheel body to rotate accurately

Engineering Contradiction:

Improvetransmission structureVSAvoidfocus tracking accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent substitutes the conventional gear transmission system that suffers from transmission gap with a worm gear mechanism. This substitution maintains structural simplicity while fundamentally improving reliability by eliminating the gap that causes focus tracking errors, ensuring the follow focus gear accurately follows handwheel body rotation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the follow focus gear does not follow the handwheel body rotation due to transmission gap, then the structure remains simple, but focus control fails

Engineering Contradiction:

Improvetransmission structureVSAvoidfocus control precision

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent replaces the flawed gear transmission system with a worm gear mechanism that eliminates transmission gap. This substitution preserves structural simplicity while dramatically improving operational precision, ensuring that focus control responds accurately and consistently to handwheel body rotation without the tracking failures caused by mechanical gaps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration ensures that the follow focus gear rotates consistently with the handwheel body, enhancing user control and preventing focus failures, while also improving the damping feel and smoothness of the rotation.

Implementation Method 1

an angle between the active worm and the driven worm is 90°, and the first worm gear is meshed with the second worm gear

Methodology Applied

Scientific EffectWorm gear meshing: Worm Drive

Implementation Method 2

the active worm is further provided with a damping ring, an outer periphery of the damping ring is abutted against an inner side wall of the gear box

Methodology Applied

Scientific EffectDamping: Damping

Implementation Method 3

the gear box is provided with a lubricant for lubricating the damping ring and an inner side wall of the gear box

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS12222629B2Follow focus

Publication Date: 2025.02.11 SHEN ZHEN NEEWER TECH CO LTD

AI summary

Disclosed is a follow focus. The follow focus includes the gear box, the handwheel assembly and the follow focus assembly. The handwheel assembly includes a handwheel body and an active worm, the active worm is fixed to the handwheel body and extends toward the gear box, and the active worm is provided with a first worm gear; and a follow focus assembly includes a follow focus gear and a driven worm, the driven worm is fixed to the follow focus gear and extends toward the gear box, the driven worm is provided with a second worm gear, an angle between the active worm and the driven worm is 90°, and the first worm gear is meshed with the second worm gear.