Chip-Inductor Inductive Position Detector for Higher Resolution
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Solution Overview
Problem
Existing inductive position detectors face challenges in achieving high resolution and accuracy while maintaining a small size, due to limitations in reducing conductor target pitch and detection coil size, which affects signal-to-noise ratio and requires complex signal processing, and are costly for small-volume production.
Innovation Solution
An inductive position detector using chip inductors surface-mounted on a wiring board with different spatial phases to detect magnetic field changes from conductor targets, allowing for flexible layout and uniform output signals, and utilizing multilayer chip inductors to increase turn number without excessive cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pitch of conductor targets is reduced to increase shaft angle multiplier and improve resolution, then the size of the position detector is reduced, but the interlinkage flux number is reduced and signal voltage is reduced, lowering the signal-to-noise ratio and making accurate detection difficult
Solution Approach 1:
The patent transitions from planar conductor patterns on a printed wiring board to three-dimensional chip inductors with multiple turns. This dimensional change allows the detection coil to achieve a greater effective turn number within a compact footprint, thereby maintaining sufficient signal voltage and signal-to-noise ratio even when the pitch between conductor targets is reduced for higher resolution detection.
Solution Approach 2:
The patent changes the physical parameters of the detection coil by using chip inductors with optimized turn numbers, wire diameters, and effective areas. These parameter adjustments enable the detection coil to generate adequate signal voltage despite the reduced pitch of conductor targets, thus maintaining reliable signal-to-noise ratio while achieving higher detection resolution.
2Reliability
If the number of turns of the detection coil is increased to provide sufficient signal voltage, then the signal-to-noise ratio is improved, but the size of the detection coil increases, making it difficult to reduce the overall detector size
Solution Approach 1:
The patent employs three-dimensional chip inductor structures that achieve multiple turns within a compact volume. This vertical stacking and spatial arrangement of turns allows the detection coil to provide sufficient signal voltage without increasing the planar footprint, thus enabling both high signal quality and small detector size.
Solution Approach 2:
The chip inductor structure implements nested turns where multiple loops are arranged in a compact, space-efficient manner. This nesting allows the detection coil to achieve a high turn number within a small effective area, providing adequate signal voltage while maintaining a compact detection coil size suitable for small-volume detectors.
3Reliability
If a multilayer printed wiring board is used to increase the turn number of the detection coil, then the signal voltage is improved, but the production complexity and cost increase due to limitations in pattern width, pattern spacing, via-hole diameter and the like
Solution Approach 1:
The patent extracts the detection coil function from the printed wiring board conductor pattern and implements it using separate chip inductor components. This extraction eliminates the need for complex multilayer PCB routing, via-holes, and inter-layer connections, thereby significantly reducing production complexity while maintaining the ability to achieve sufficient turn numbers for adequate signal voltage.
Solution Approach 2:
The patent uses standardized, commercially available chip inductors instead of custom-designed multilayer PCB traces. These off-the-shelf components are cost-effective for small-volume production, eliminate the need for expensive and complex multilayer board fabrication processes, and provide consistent electrical characteristics without requiring specialized production infrastructure.
4Measurement precision
If conductor targets are arranged with smaller pitch to increase shaft angle multiplier, then the detection resolution is improved, but the number of detection cycles per rotation remains limited by the physical constraints of the detection coil size
Solution Approach 1:
The patent uses three-dimensional chip inductor structures that provide adequate signal voltage without requiring large planar dimensions. This enables the system to accommodate smaller pitch between conductor targets arranged circumferentially, thereby increasing the shaft angle multiplier and detection resolution while maintaining sufficient signal quality from each detection cycle.
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 detector achieves higher design flexibility, smaller size, and improved detection resolution with uniform signal outputs, addressing the limitations of previous technologies and enabling accurate rotational position detection.
Implementation Method 1
a voltage induced in the detection coil by an AC magnetic field generated by the excitation coil is changed according to a positional relationship between the detection coil and the conductor target
Implementation Method 2
Position detectors of the induction type are adapted to move a movable portion holding a conductor in an AC magnetic field and detect a magnetic field change caused by electric current induced in the conductor
Data Source
AI summary
The inductive position detector includes: a stator having a wiring board; a rotor having a non-conductive component disposed in opposed relation to the stator and rotatable relative to the stator about a rotation axis; a conductor pattern held by the non-conductive component so as to have cyclicity (geometrical periodicity) circumferentially about the rotation axis, and movable to pass through a rotation track defined about the rotation axis as the rotor is rotated; and a plurality of chip inductors surface-mounted on a major surface of the wiring board of the stator in opposed relation to the rotation track so as to have different spatial phases with respect to the conductor pattern, and respectively serving as detection coils that detect a magnetic field change occurring due to the passage of the conductor pattern.