Flexible Scale Rotation Detection with Segmented Annular Member
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Solution Overview
Problem
Existing rotation detection systems for endlessly rotatable operation rings in optical apparatuses face accuracy issues due to variations in tensile force and thermal expansion differences between the operation ring and attached sheets, leading to errors in rotation detection.
Innovation Solution
A rotation detection apparatus featuring a flexible scale member fixed to an annular member with multiple convex and concave portions along its circumference, where both ends of the scale member are securely attached, allowing for precise detection of relative rotation and minimizing the impact of thermal changes and component variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sheet is attached to the inner circumferential surface of the operation ring with tensile force to prevent floating, then the sheet remains securely attached, but variation in tensile force causes variation in circumferential length of the scale and error in circumferential width of the gap, decreasing rotation detection accuracy
Solution Approach 1:
The operation ring is divided into multiple convex portions and concave portions along the circumferential direction. The scale is segmented to fit between these portions, with both ends fixed to the circumferential portion. This segmentation allows the scale to be securely attached without requiring excessive tensile force, thereby maintaining rotation detection accuracy.
Solution Approach 2:
The convex portions and concave portions are strategically positioned to provide localized support and fixation points for the scale. The concave portions receive the ends of the scale, providing stable fixation without requiring high tensile force across the entire scale, thus reducing dimensional variations.
2Measurement precision
If the length of the scale and the width of the gap between the both ends of the sheet are adjusted by peeling the sheet off and re-attaching it, then the detection accuracy can be improved, but such work takes time
Solution Approach 1:
The operation ring is pre-formed with multiple convex portions and concave portions during manufacturing. The scale is designed to fit between these pre-formed portions, eliminating the need for post-manufacturing adjustment by peeling and re-attaching. This preliminary structuring ensures accurate detection from the outset.
3Adaptability or versatility
If a sheet is attached to the operation ring, then the scale can be formed, but when linear expansion coefficients of the operation ring and the sheet have a difference, a temperature change may cause a change in width of the gap and peeling of the sheet
Solution Approach 1:
The operation ring is segmented into multiple convex portions and concave portions, allowing the scale to be fixed at multiple discrete points rather than requiring continuous attachment. This segmentation reduces the overall tensile force required and minimizes thermal expansion differences between the operation ring and the scale material.
Solution Approach 2:
The design accommodates temperature changes by allowing the scale to expand and contract within the constraints of the convex and concave portions. The flexible attachment at the concave portions enables the scale to adapt to thermal expansion without causing gap width changes or peeling.
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 enhances detection precision and stability, enabling high-resolution rotation detection and position control of optical components, such as focus lenses, while reducing the risk of plastic deformation and pitch variations.
Implementation Method 1
a scale member having flexibility and being fixed to a circumferential portion of the annular member
Data Source
AI summary
The rotation detection apparatus including an annular member, a scale member having flexibility and being fixed to a circumferential portion of the annular member, and a detector facing the scale member and configured to detect relative rotation between the scale member and the detector. The circumferential portion of the annular member includes multiple convex portions and multiple concave portions along a circumferential direction of the annular member. The scale member is in contact with the multiple convex portions. Both ends, in the circumferential direction, of the scale member are fixed to the circumferential portion.