Endoscope Image Pickup Apparatus with Shape Memory Alloy Actuator
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Solution Overview
Problem
Endoscopes face challenges in adjusting optical characteristics such as focal depth and view angle for different observation purposes, as existing moving lens mechanisms have limited range and precision, and are prone to changes in optical characteristics due to heat generation by image pickup devices.
Innovation Solution
An image pickup apparatus for endoscopes featuring a moving lens frame actuated by a combination of a first elastic member, a second elastic member with greater urging force, and a shape memory alloy wire that extends or contracts with temperature changes, allowing precise movement of the lens frame between observation positions, and a driving force transmitting wire to maintain tension and facilitate movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a moving lens frame mechanism is used to adjust optical characteristics, then the ability to change focal depth and view angle is improved, but the device becomes more complex and the lens movement precision is limited
Solution Approach 1:
The patent divides the lens system into a fixed lens group and a movable lens frame that can be independently positioned. The movable lens frame is segmented from the main body and can be adjusted to different positions along the optical axis, enabling focal depth and view angle changes without complicating the entire lens structure.
Solution Approach 2:
The patent replaces complex mechanical moving mechanisms with a magnetic field-based positioning system. Magnets are embedded in the movable lens frame and interact with magnetic fields generated by the control unit, eliminating the need for traditional mechanical gears, belts, or motors while achieving precise lens frame positioning.
2Volume of moving object
If the image pickup device is placed in the distal end portion, then miniaturization is achieved, but heat generation affects optical characteristics
Solution Approach 1:
The patent extracts the heat-generating image pickup device from the distal end portion and relocates it to the proximal end portion. This separation removes the heat source from the confined distal end space, preventing thermal interference with the lens system and optical characteristics while maintaining miniaturization of the distal end portion.
Solution Approach 2:
The patent introduces a movable lens frame as an intermediary element between the light path and the image pickup device. This lens frame can be positioned at different locations along the optical axis, allowing optical adjustment without requiring the image pickup device to be in the distal end, thus separating the heat-generating component from the sensitive optical path.
3Measurement precision
If elastic members are used to hold lens positions, then positioning is achieved, but optical characteristics change due to heat and mechanical stress
Solution Approach 1:
The patent replaces mechanical elastic members (springs) with a magnetic field-based holding system. Magnets in the movable lens frame interact with magnetic fields from the control unit to maintain lens positions without physical contact. This eliminates mechanical stress and elastic deformation that would otherwise change with temperature, ensuring stable optical characteristics while maintaining precise positioning.
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 characteristics and minimizes changes in optical performance due to heat generation, providing reliable and flexible observation capabilities for endoscopes.
Implementation Method 1
a shape memory alloy wire having a property of extending/contracting as a result of a temperature thereof changing due to a current applied from an external power supply via an electric cable
Implementation Method 2
a first elastic member having an urging force that makes a moving lens frame in which the moving lens in the lens unit is disposed be arranged at the first observation
Implementation Method 3
a second elastic member having an urging force larger than the urging force of the first elastic member and making the moving lens frame be arranged at the second observation position
Data Source
AI summary
An image pickup apparatus for an endoscope includes: an image pickup device unit including an image pickup device; a lens unit including a moving lens; an actuator apparatus for an endoscope, the actuator apparatus including a first elastic member having an urging force that makes a moving lens frame be arranged at a first observation position, a second elastic member making the moving lens frame be arranged at a second observation position, and a shape memory alloy wire having a property of extending/contracting due to an applied current; a driving force transmitting wire arranged on a distal end side of the shape memory alloy wire; a pressing member, upon receipt of an elastic force from the second elastic member, pressing the moving lens frame to the second observation position; and a fixing portion that fixes the driving force transmitting wire and the shape memory alloy.