Hollow-Cylindrical Linear Motor for Endoscope Focusing
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Solution Overview
Problem
Existing linear motors for endoscopes are too large and rigid, with limited optical quality and inability to adjust focal length, and require complex control systems and high-accuracy assembly, making them unsuitable for miniaturization and precise positioning in endoscopic applications.
Innovation Solution
A rotationally symmetrical linear motor with a hollow-cylindrical rotor and stator design, utilizing annular coils and permanent magnets, allowing for precise adjustment of optical elements by shifting the sleeve, with a direct correlation between coil current and rotor position, eliminating the need for additional position sensors and using simple, geometrically easy-to-manufacture components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a permanent magnet is moved within a stator coil to adjust focal length, then the lens system can be focused, but the drive becomes sluggish due to large mass and requires additional displacement sensors
Solution Approach 1:
The patent replaces the traditional permanent magnet linear motor with a voice coil motor that uses electromagnetic interaction between a coil and a magnetically conductive element. This substitution eliminates the need for heavy permanent magnets while achieving precise focal length adjustment through controlled electromagnetic forces, directly resolving the contradiction between positioning precision and moving mass.
2Ease of operation
If complex control circuits are used to generate traveling fields for linear motor operation, then continuous rotor displacement is achieved, but device complexity increases
Solution Approach 1:
The patent employs periodic alternating current through the voice coil to generate oscillating electromagnetic forces that move the rotor continuously. This periodic action approach simplifies the control circuitry compared to complex traveling field generation, achieving continuous positioning through straightforward AC drive while maintaining ease of operation.
3Ease of operation
If stable rotor positions are realized by pole shoes with high manufacturing accuracy, then continuous rotor displacement is enabled, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces the mechanical pole shoe guidance system with a magnetic field-based positioning system using voice coil electromagnetic forces. This substitution eliminates the need for high-precision mechanical pole shoes while enabling continuous rotor displacement through controlled electromagnetic interaction, directly resolving the contradiction between operational ease and manufacturing precision requirements.
4Volume of moving object
If miniaturized motor components are used to reduce endoscope size, then the endoscope can be smaller, but driving forces decrease
Solution Approach 1:
The patent optimizes the voice coil motor parameters including coil turns, current density, and magnetic circuit geometry to maximize force density. By carefully adjusting these parameters, the system achieves sufficient driving force in a miniaturized configuration, resolving the contradiction between reduced motor volume and maintained driving force for endoscopic applications.
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
Enables rapid, continuous, and exact positioning of optical systems with high driving forces and low power loss, facilitating miniaturization to a few millimeters, reducing heat generation, and simplifying assembly while maintaining precise control over the beam path.
Implementation Method 1
A phase-shifted energization of the coils generates a traveling field, which causes a displacement of the rotor with axial permanent magnets
Implementation Method 2
The stable positions of the rotor are realized by the pole shoes attached to the stator
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The motor has a stator (1) with a coil (9), which is enclosed by a return element (10) in entire length of the coil. A rotor (2) is displaced parallel to the stator and is partially enfolded by the coil. A pole shoe (4) is arranged between two permanent magnets (7, 8). Length of the rotor corresponds to length of the return element of the stator. An optical element is accommodated at the interior of the rotor. A slide sleeve (6) with a material with lower frictional coefficient is arranged at a surface between the stator and the rotor. An independent claim is also included for a method for operating a linear motor.