Electromagnetic Position Detector Offset Cancellation
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Solution Overview
Problem
Existing electromagnetic induction type position detectors face accuracy issues due to voltage offset caused by manufacturing errors and spatial modulation of flux units, requiring additional space for symmetrical transmission windings to cancel out voltages and necessitate separate gap measurement devices.
Innovation Solution
The design incorporates a primary-side member with overlapping transmission windings forming alternating positive and negative polarity loops, and a secondary-side member with flux modulation units, where the windings are adjusted to invert loop dispositions and overlap partially, using alternating currents to cancel induced voltages and reduce offsets without requiring additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two transmission winding portions having shapes symmetrical to each other are provided outside the reception winding to cancel induced voltages and reduce offset, then measurement precision is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines the offset cancellation function and position detection function into a single integrated structure. The transmission winding is configured with alternating positive-polarity and negative-polarity loops that are spatially modulated, allowing the same winding to both generate the magnetic field for position detection and cancel offset voltages through its symmetric loop arrangement, eliminating the need for separate cancellation windings.
Solution Approach 2:
The transmission winding serves multiple functions simultaneously: it generates the magnetic field for inducing voltage in the reception winding for position detection, and it cancels offset voltages through its alternating polarity loop configuration. This multi-functional design reduces device complexity while maintaining measurement precision.
2Measurement precision
If two transmission winding portions having shapes symmetrical to each other are provided outside the reception winding to cancel induced voltages and reduce offset, then measurement precision is improved, but the device occupies large space
Solution Approach 1:
The patent merges the offset cancellation function and position detection function into a single integrated structure. The transmission winding is configured with alternating positive-polarity and negative-polarity loops that are spatially modulated, allowing the same winding to both generate the magnetic field for position detection and cancel offset voltages through its symmetric loop arrangement, eliminating the need for separate cancellation windings.
Solution Approach 2:
The patent uses spatial modulation of the transmission winding loops in the vertical direction (stacked layers) rather than expanding horizontally. The positive-polarity and negative-polarity loops are arranged in different layers with alternating current supply, achieving offset cancellation without increasing the horizontal footprint of the device.
3Measurement precision
If the offset is present due to manufacturing errors and spatial modulation, then position detection requires additional correction measurements, but separate gap measurement devices are necessitated
Solution Approach 1:
The patent applies preliminary anti-action by configuring the transmission winding to proactively cancel offset voltages before they affect position detection accuracy. The alternating positive-polarity and negative-polarity loops generate equal and opposite magnetic fluxes that compensate for manufacturing errors and spatial modulation effects, eliminating the need for post-detection correction measurements or separate gap measurement devices.
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 achieves higher accuracy and compactification by minimizing voltage offsets, eliminating the need for separate gap measurement devices and allowing for precise position detection without large space requirements.
Implementation Method 1
The linear type scale and the rotary type scale detect a position by electromagnetic induction of patterns disposed so as to face each other in parallel to each other
Implementation Method 2
an eddy current is generated in a flux modulation unit in a scale, and as a result, an induced voltage is generated in a reception winding in the slider
Implementation Method 3
providing an excitation signal to the transmission winding in a slider, an eddy current is generated in a flux modulation unit in a scale, and as a result, an induced voltage is generated in a reception winding in the slider
Data Source
AI summary
A transmission winding portion having a positive-polarity loop and a negative-polarity loop alternately formed so as to partially overlap with each other in the extending direction of a scale, arrangement of the positive-polarity loop and the negative-polarity loop being adjusted such that the positive-polarity loop and the negative-polarity loop on both sides with respect to the intermediate position in the longitudinal direction of the transmission winding portion are inverted; a first reception winding that covers the transmission winding portion in the width direction of the scale, that has a length, corresponding to the cycle of the cycle pattern of the transmission winding portion, and that is formed into a rectangular pattern; a second reception winding having a shape symmetrical to the first reception winding with respect to the intermediate position in the longitudinal direction of the transmission winding portion.