Optical Unit Lens Barrel Position Sensing Without Adhesive Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical units with voice coil motors for endoscopes face challenges in accurately detecting the position of movable lenses due to adhesive-related issues affecting the magnetic sensor's output characteristics and sensitivity, leading to potential misalignment and reduced performance.
Innovation Solution
The optical unit incorporates a position detection unit with a magnetic sensor mounted on a substrate, where the sensor is not in contact with any adhesive, and a base member is fixed to the position defining surface with adhesives, ensuring accurate positioning and preventing output characteristic changes, while using a voice coil motor with magnets and coils to move the lens barrel along the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the magnetic sensor is fixed directly to the position defining surface with adhesive, then the device complexity is reduced, but the measurement precision deteriorates due to adhesive-related shifts and stress affecting sensor output characteristics
Solution Approach 1:
A base member is introduced as an intermediary component between the magnetic sensor and the position defining surface. The base member is fixed to the position defining surface with adhesive, while the magnetic sensor is mounted on the base member without direct adhesive contact. This intermediary structure prevents adhesive-related stress and shifts from affecting the sensor, thereby maintaining measurement precision while still enabling a relatively simple overall device structure.
2Ease of manufacture
If the magnetic sensor is fixed with adhesive, then the ease of manufacture is improved, but the reliability deteriorates due to potential changes in sensor sensitivity and output characteristics
Solution Approach 1:
The base member serves as a mediator that separates the adhesive bonding process from the magnetic sensor. The adhesive is applied between the base member and the position defining surface, not directly to the sensor. This maintains ease of manufacture through simple adhesive bonding while ensuring reliability by preventing adhesive-induced changes in sensor sensitivity and output characteristics.
3Measurement precision
If the magnetic sensor is kept away from adhesive, then the measurement precision is improved, but the device complexity increases due to additional base member and mounting structure
Solution Approach 1:
The base member is designed to serve multiple functions: it provides a mounting surface for the magnetic sensor, defines the position of the sensor relative to the position defining surface, and serves as the bonding surface for adhesive attachment to the third barrel. By consolidating these functions into a single component, the structure remains relatively simple while achieving the goal of keeping the sensor away from adhesive.
4Manufacturing precision
If the base member defines the distance between position defining surface and sensor mounting surface, then the manufacturing precision is improved, but the device complexity increases due to the additional component
Solution Approach 1:
The base member simultaneously serves as a positioning element that defines the distance between the position defining surface and sensor mounting surface, and as a structural component for mounting the magnetic sensor and attaching to the third barrel. This multi-functionality achieves manufacturing precision without proportionally increasing device complexity.
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 ensures precise position detection and movement of the lens barrel, maintaining the sensitivity and accuracy of the magnetic sensor, reducing the risk of adhesive-related shifts or stress, and minimizing the number of components needed for position detection.
Implementation Method 1
a coil fixed to the second barrel and configured to generate a magnetic field for moving the first barrel by interacting with a magnetic field generated by the magnet
Implementation Method 2
a magnetic sensor configured to detect the magnetic field generated by the magnet and to generate a detection signal having a corresponding relation with a position of the first barrel
Data Source
AI summary
An optical unit includes a first barrel, a second barrel, a third barrel, and a position detection unit. Eight magnets including first and second magnets are fixed to the first barrel. A first and second coils are fixed to the second barrel. The position detection unit includes a magnetic sensor configured to detect magnetic fields generated by the first and second magnets and to generate a detection signal having a corresponding relation with a position of the first barrel. The third barrel includes a position defining surface parallel to a moving direction of the first barrel. The position detection unit is fixed to the position defining surface.