Shape Memory Alloy Actuator for Endoscope Lens Positioning
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Solution Overview
Problem
Existing endoscope image pickup apparatuses face challenges in varying optical properties such as depth of focus, image magnification, and viewing angle, which are essential for effective observation and treatment within body cavities or industrial facilities, due to limitations in moving optical lenses along the optical axis.
Innovation Solution
An image pickup apparatus with a solid-state image pickup device unit, a fixed lens frame, a movable lens frame, and an actuator that includes a shape memory alloy wire, allowing for the movement of lenses along the optical axis to adjust optical properties, utilizing a combination of elastic members and a guide pipe to control the lens frame's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a movable lens frame is used to vary optical properties, then optical performance is improved, but device complexity increases
Solution Approach 1:
The patent applies the dynamics principle by making the lens frame movable rather than fixed. The lens frame can move along the optical axis to change the optical properties (focusing, zooming) of the image pickup apparatus. This dynamic structure allows the system to adapt to different observation requirements while maintaining relatively simple construction through the use of shape memory alloy actuators.
2Volume of moving object
If the distal end portion size is reduced, then ease of insertion is improved, but optical performance deteriorates
Solution Approach 1:
The patent applies the nesting principle by placing the movable lens frame and actuator mechanism within the existing lens barrel structure. The shape memory alloy wire is coiled and positioned within the lens frame assembly, allowing the actuation mechanism to be nested within the compact distal end portion. This enables space-efficient design that maintains optical performance while reducing overall size for easier insertion.
3Device complexity
If shape memory alloy wire is used for actuation, then device complexity is reduced, but control precision deteriorates
Solution Approach 1:
The patent applies the intermediary principle by introducing a guide pipe as a mediator between the shape memory alloy wire actuator and the movable lens frame. The guide pipe constrains the movement of the lens frame to a precise linear path along the optical axis, ensuring accurate positioning despite the non-linear contraction characteristics of the shape memory alloy wire. This intermediary component translates the actuator's motion into precise, controlled lens frame displacement.
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 precise adjustment of optical properties, improving the ability to focus and zoom within the endoscope, enhancing observation capabilities and reducing the size of the endoscope's distal end portion while maintaining optical performance.
Implementation Method 1
an actuator that has one end connected to the movable lens frame and that moves the movable lens frame forward and backward, and that includes a rigid member provided so as to extend as far as a vicinity of a rear end at which the solid-state image pickup device unit is disposed, and a shape memory alloy that is coupled to the rigid member
Data Source
AI summary
An image pickup apparatus of the present invention varies optical properties by moving a part of lenses of an objective lens, and includes a solid-state image pickup device unit that is disposed at a rear-end section and that subjects a subject image to photoelectric conversion, a fixed lens frame that retains the objective lens that is disposed in front of the solid-state image pickup device unit, a movable lens frame that retains the part of lenses that moves along a photographing optical axis O inside the lens frame, and an actuator having one end connected to the movable lens frame and that moves the movable lens frame forward and backward. The actuator includes a rigid member provided so as to extend to the vicinity of the rear end at which the solid-state image pickup device unit is disposed and a shape memory alloy that is coupled to the rigid member.