Inductive Encoder Scale Pattern with Aligned Loop Centers
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Solution Overview
Problem
Conventional scale patterns, especially solid patterns, face measurement accuracy issues due to scratches that cause deviations in the center of gravity of magnetic flux density distribution, leading to errors in measurement results.
Innovation Solution
A scale pattern comprising multiple loop portions arranged such that their centers of gravity coincide in the measurement direction, allowing the pattern to maintain accuracy even if individual loop portions are damaged, with nested loop configurations enhancing signal strength and preventing center of gravity deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid pattern is used instead of a coil pattern, then the scale pattern can function even when scratched, but the center of gravity of magnetic flux density distribution may deviate from the center of gravity of the pattern when scratched, causing measurement errors
Solution Approach 1:
The solid pattern is divided into multiple loop portions (first loop portion and second loop portion) that are spaced apart. This segmentation allows the pattern to maintain functionality when partially damaged while controlling the center of gravity of magnetic flux density distribution to prevent measurement errors.
2Manufacturing precision
If a coil pattern is used, then high resolution can be achieved, but the pattern may be easily broken and may not function as a scale pattern
Solution Approach 1:
Multiple loop portions are nested or arranged within the unit pattern structure. The first loop portion and second loop portion are positioned such that their centers of gravity align in the measurement direction, creating a nested configuration that maintains both resolution and durability.
3Measurement precision
If multiple loop portions are arranged to maintain center of gravity alignment, then measurement accuracy is maintained even when scratched, but the pattern complexity increases
Solution Approach 1:
The loop portions are arranged with specific local quality characteristics - their centers of gravity are aligned in the measurement direction while being spaced apart. This localized arrangement maintains measurement accuracy without requiring complete redesign of the entire scale pattern structure.
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
The solution ensures measurement accuracy is maintained by preventing center of gravity deviation in the measurement direction, even if loop portions are scratched or broken, while maintaining signal efficiency and high resolution.
Implementation Method 1
an eddy current is generated in the direction of the arrow in the drawings by a transmission coil (not shown)
Implementation Method 2
an eddy current is generated in the direction of the arrow in the drawings by a transmission coil
Data Source
AI summary
A scale capable of maintaining measurement accuracy even if the pattern of the scale pattern is scratched is provided. The scale 2 comprises a scale pattern 4 having a plurality of unit patterns provided at a predetermined pitch along the measurement direction on a surface thereof. At least one of the plurality of unit patterns comprises a plurality of loop portions 8 formed with conductors in a loop shape. The plurality of loop portions 8 included in the unit pattern are arranged so as to be spaced from each other such that the centers of gravity of the loop portions 8 are at the same position in the measurement direction on the surface of the scale 2. Thereby, the plurality of loop portions 8 included in the unit pattern can prevent deviation of the center of gravity of the magnetic flux distribution in the measurement direction, even if any of the plurality of the loop portions 8 is scratched. Therefore, the scale 2 can maintain the measurement accuracy.