Electromagnetic Induction Encoder Asymmetry
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Solution Overview
Problem
Existing electromagnetic induction type encoders require multiple scale coils, leading to lengthy wiring and reduced signal intensity due to impedance, making it difficult to achieve strong signal intensity with offset reduction, especially in the yaw direction.
Innovation Solution
The encoder features two sets of transmitting, receiving, and scale coils disposed symmetrically around the center of the scale, with one set of scale coils shifted by 1/2 phase, allowing for reduced wiring and eliminating the need for additional receiving coils between transmitting coils, thereby enhancing signal intensity and durability against yaw fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple scale coils are disposed to reduce offset, then offset reduction is achieved, but wiring length increases and signal intensity decreases
Solution Approach 1:
The patent applies asymmetry by shifting scale coils of one set by 1/2 phase of scale pitch relative to the other set, creating an asymmetric configuration that reduces offset while maintaining short wiring length and strong signal intensity
Solution Approach 2:
The patent merges the functions of multiple receiving coils into a single receiving coil that detects combined magnetic flux changes, reducing the number of scale coils needed and thereby reducing wiring length while maintaining offset reduction capability
2Measurement precision
If three rows of scale coils are disposed, then offset is reduced, but wiring length increases and impedance increases
Solution Approach 1:
The patent merges the functions of multiple receiving coils into a single receiving coil that detects combined magnetic flux changes, reducing the number of scale coils needed and thereby reducing wiring length and impedance
Solution Approach 2:
The single receiving coil performs multiple functions by detecting magnetic flux changes from multiple transmitting coils simultaneously, eliminating the need for separate receiving coils and reducing overall wiring complexity
3Measurement precision
If receiving coils are disposed between transmitting coils, then offset is reduced, but device complexity and cost increase
Solution Approach 1:
The patent merges the functions of multiple receiving coils into a single receiving coil that detects combined magnetic flux changes, reducing the number of components needed and thereby reducing manufacturing cost while maintaining offset reduction capability
Solution Approach 2:
The single receiving coil performs multiple functions by detecting magnetic flux changes from multiple transmitting coils simultaneously, eliminating the need for separate receiving coils and reducing overall manufacturing 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 results in a highly accurate, compact, and cost-effective encoder with reduced positional errors and improved durability against environmental factors, using fewer grid layers and eliminating the need for connection wiring, while maintaining strong signal intensity.
Implementation Method 1
electromagnetic induction type encoder includes a number of scale coils 14,16 arrayed on a scale 10 along the measurement direction, and transmitting coils 24,26 and receiving coils 20, 22 disposed on a grid (may be referred to as a slider, too) 12 relatively movable in the measurement direction with respect to the scale 10, and is capable of detecting a relative movement amount of the scale 10 and the grid 12 from changes in magnetic fluxes detected by the receiving coils via the scale coils when the transmitting coils are magnetized
Data Source
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AI summary
The invention provides a highly accurate and inexpensive electromagnetic induction type encoder capable of acquiring strong signal intensity with the offset reduced by a short scale coil, and is durable against fluctuations in the yaw direction, which includes a number of scale coils 14 arrayed on a scale 10 along the measurement direction, and transmitting coils 24 and receiving coils 20 that are disposed on a grid 12 relatively movably in the measurement direction with respect to the scale, and which detects a relative movement amount of the scale and the grid from changes in magnetic fluxes detected by the receiving coils via the scale coil when the transmitting coils are magnetized, wherein a plurality of sets of the transmitting coils (24A, 24B), the receiving coils (20A, 20B) and the scale coils (14A, 14B) are disposed symmetrically with respect to the center of the scale, and scale coils of one set located at a symmetrical position around the center of the scale is disposed with 1/2 phase of the scale pitch shifted with respect to scale coils of the other set.