Magnetic Coupling Lens Actuator for Endoscope Durability
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Solution Overview
Problem
Conventional magnetic coupling actuators in endoscopes face limitations in achieving sufficient lens displacement due to the length constraints of shape memory alloy wires, which restrict the freedom in designing optical systems and compromise durability.
Innovation Solution
A magnetic coupling lens driving actuator design that includes a movable lens, a magnetic body, a lens tube for airtight sealing, and a wire member connected to permanent magnets, allowing for equal movement of the lens and wire expansion/contraction, with position regulating members and a bendable tube to enhance durability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a longer shape memory alloy wire is used to achieve longer lens displacement, then the lens displacement amount is improved, but the wire durability deteriorates due to excessive expansion/contraction
Solution Approach 1:
The single long wire is divided into multiple wire members (first wire member and second wire member) connected in series. Each wire member has a limited expansion/contraction range that matches its segment length, preventing excessive deformation while achieving the total required lens displacement through cumulative effect of multiple segments.
Solution Approach 2:
A magnetic coupling mechanism is introduced as an intermediary between the wire members and the lens holder. The magnetic body coupled to the lens holder interacts with permanent magnets on the lens tube, enabling precise control of lens displacement without directly transmitting full wire expansion forces to the lens, thereby protecting the wire from excessive stress.
2Length of moving object
If a longer actuator is used to achieve longer lens displacement, then the lens displacement amount is improved, but the device complexity increases due to space constraints in rigid section
Solution Approach 1:
The wire members are encased within a bendable tube, creating a nested structure where the flexible wire assembly is contained within the protective tube. This allows the actuator to achieve extended displacement through the bendable section while maintaining a compact appearance in the rigid section, avoiding the need for a visibly long actuator.
Solution Approach 2:
The actuator utilizes the dynamic expansion and contraction of shape memory alloy wire members to achieve lens displacement. Instead of a static mechanical linkage, the system employs dynamic material transformation (shape memory effect) to convert electrical energy into precise lens movement, simplifying the mechanical structure while maintaining functionality.
3Ease of operation
If the shape memory alloy wire is expanded/contracted more than the desired displacement to overcome static friction, then the lens can be moved, but the wire durability deteriorates due to excessive expansion/contraction
Solution Approach 1:
The wire system is segmented into multiple members, each responsible for a specific portion of the displacement. The magnetic coupling mechanism ensures that each segment only expands/contracts by the amount necessary for its segment of the journey, preventing the excessive expansion required to overcome static friction from propagating through the entire wire length.
Solution Approach 2:
The magnetic coupling acts as a mediator that decouples the friction-overcoming function from the wire expansion function. The magnetic body and permanent magnets create the necessary force to overcome static friction independently, allowing the wire members to expand/contract only by the precise amount needed for lens displacement without the excessive expansion required to overcome friction.
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 reduces the expansion/contraction of the shape memory alloy wire, improving the durability and efficiency of the actuator, allowing for precise movement of the lens while maintaining airtight sealing and simplifying assembly, thus enhancing the optical system's durability and performance.
Implementation Method 1
a shape memory alloy wire 906 is connected to one side of the permanent magnet 905. The permanent magnet 905 moves in a direction that is parallel to the optic axis 900 with the expansion and contraction of the shape memory alloy wire 906.
Implementation Method 2
The lens holder 903 and the permanent magnet 905 are mutually magnetically coupled via the lens tube 904.
Data Source
AI summary
A magnetic coupling lens driving actuator includes an imaging element; a movable lens that is movable in a direction of an optic axis; a magnetic body that is coupled to the movable lens; a lens tube that encases and airtightly seals the imaging element, the movable lens, and the magnetic body; a magnetic field producing unit that is disposed on an outer surface of the lens tube and that is movable in the direction of the optic axis; and a wire member that has one end thereof attached to the magnetic field producing unit, and that is operative to move the magnetic field producing unit in the direction of the optic axis. The magnetic field producing unit includes two magnetic field producing members disposed with a predetermined gap therebetween in the direction of the optic axis, the magnetic body is disposed opposed to the predetermined gap within the lens tube, and the movable lens is moved by any one of deformation and movement of the wire member.