Movable Lens Backlash Prevention via Magnetic Pressing
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Solution Overview
Problem
Existing image pickup apparatuses with movable lens frames, such as those in endoscopes, face challenges in preventing backlash during movement, which affects the precision and reliability of focal point switching, and often require complex configurations to maintain accurate positioning and prevent mechanical backlash.
Innovation Solution
The proposed solution involves a magnetic member placed outside the holding frame's outer circumferential surface, orthogonal to the optical axis, which generates an attracting force to the magnet pairs on the lens frame, ensuring stable movement and preventing backlash by pressing the lens frame against the inner surface of the holding frame, thus allowing for smooth forward and backward movement without mechanical backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a voice coil motor is used to move the movable lens frame, then the lens frame can be moved in the optical axis direction, but mechanical backlash occurs during movement affecting positioning precision
Solution Approach 1:
A magnetic member is introduced as an intermediary between the movable lens frame and the holding frame. This magnetic member generates magnetic force to press the outer circumferential surface of the movable lens frame against the inner circumferential surface of the holding frame, eliminating gaps and preventing backlash during movement, thereby improving positioning precision while maintaining movability
Solution Approach 2:
The patent replaces pure mechanical coupling with a magnetic field-based coupling system. The magnetic member generates magnetic force to create friction between the movable lens frame and holding frame, substituting mechanical interference fits or complex mechanical locking mechanisms with a more reliable magnetic field-based friction coupling that prevents backlash
2Manufacturing precision
If complex configurations are used to prevent backlash, then positioning accuracy improves, but device complexity increases
Solution Approach 1:
The magnetic member serves as a simple intermediary component that eliminates the need for complex mechanical backlash prevention mechanisms. By generating magnetic force to press the lens frame against the holding frame, it achieves precise positioning with a single, simple component rather than complex mechanical systems
Solution Approach 2:
The patent replaces complex mechanical backlash prevention systems with a simple magnetic field-based friction coupling. This substitution dramatically reduces device complexity while maintaining or improving positioning precision, as the magnetic member can be integrated into the existing voice coil motor structure
3Manufacturing precision
If friction is increased to prevent backlash, then positioning stability improves, but moving force required increases
Solution Approach 1:
The magnetic member acts as an intermediary that generates controlled friction through magnetic force. This friction is sufficient to prevent backlash and improve positioning stability, while the magnetic force can be optimized to minimize the additional moving force required, balancing stability and energy consumption
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 effectively prevents backlash during the movement of the movable lens frame, ensuring precise focal point switching and achieving downsizing of the apparatus while maintaining low costs and high reliability.
Implementation Method 1
a coil that is wound on an outer circumferential surface, the coil being provided to face the magnet and generating driving force with respect to the lens frame in response to energization
Implementation Method 2
a magnetic member provided on outside of the outer circumferential surface of the holding frame in a radial direction of the holding frame that is orthogonal to the optical axis direction, the magnetic member facing the magnet only in one direction of a plurality of directions configuring the radial direction, and the magnetic member generating attracting force with respect to the magnet
Data Source
AI summary
An image pickup apparatus includes: a lens frame internally holding a movable lens, and including a magnet provided on an outer circumferential surface; a holding frame; and a magnetic member, in which the magnet includes a plurality of magnet pairs provided at uniform angles in a circumferential direction of the lens frame, each of the magnet pairs including magnets that are respectively disposed on distal end side and proximal end side along the optical axis direction of the movable lens, the magnet disposed on the distal end side has a polarity opposite in the radial direction to a polarity of the magnet disposed on the proximal end side, and the magnetic member is provided to face the magnets that configure one of the plurality of magnet pairs.