Optical Filter Holding Frame With Worm Gear Self-Locking

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Solution Overview

Problem

Conventional filter switching mechanisms in image pickup apparatuses suffer from weak holding forces, leading to unintentional filter switching due to vibrations or impacts, and increasing the size of the apparatus when torque is enhanced for better holding.

Innovation Solution

A compact optical apparatus using a worm gear mechanism with a worm and worm wheel to drive the filter holding frame, incorporating a self-locking function to stabilize the filter position, preventing unintentional switching during impacts or vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the torque of the actuator is made larger to increase the holding force, then the holding force is improved, but the actuator and finally the image pickup apparatus become larger

Engineering Contradiction:
Improveholding forceVSAvoidapparatus size
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

A dedicated lock unit is introduced as an intermediary component between the actuator and the filter frame. This lock unit engages with the filter frame at a predetermined position to provide additional locking force, allowing the actuator to maintain adequate holding force without needing to be oversized. The lock unit acts as a mediator that supplements the actuator's holding capability while keeping the overall apparatus compact.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Force

If a dedicated lock unit for locking the filter frame is added, then the holding force is improved, but the size of the image pickup apparatus increases

Engineering Contradiction:
Improveholding forceVSAvoidapparatus size
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The lock unit is integrated with the existing actuator structure rather than being a completely separate component. The lock unit shares spatial and structural elements with the actuator mechanism, merging multiple functions into a compact arrangement. This integration allows the lock unit to provide enhanced holding force without proportionally increasing the overall apparatus size, as it utilizes the same structural envelope as the actuator.

Inventive Principle:
Principle #5Merging (Combining)

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 worm gear mechanism ensures stable and compact filter positioning, maintaining the apparatus size while effectively preventing filter movement during vibrations or impacts.

Implementation Method 1

A driver including a worm (23) rotated by an actuator (20), a worm wheel (24a) that forms a worm gear with the worm (23), and a pinion (24b) that rotates with a rotation of the worm wheel (24a) and is engaged with the rack (17a)

Methodology Applied
Scientific EffectWorm gear mechanism: Worm Drive

Implementation Method 2

incorporating a self-locking function to stabilize the filter position, preventing unintentional switching during impacts or vibrations

Methodology Applied
Scientific EffectSelf-locking function: Friction

Data Source

PatentEP3722872B1Optical apparatus
Publication Date: 2025.08.27 CANON KK
  • EP3722872B1 patent drawingFigure 1
  • EP3722872B1 patent drawingFigure 2A~2B
  • EP3722872B1 patent drawingFigure 3~4

AI summary

An optical apparatus includes a holding frame configured to hold an optical element and including a rack, and a driver configured to drive the holding frame. The driver includes a worm rotated by the actuator, a worm wheel configured to form a worm gear together with the worm, and a pinion configured to rotate with a rotation of the worm wheel and engaged with the rack.