Differential Magnetic Sensing for Wider-Range Speaker Feedback
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Solution Overview
Problem
Existing speakers with magnetic sensors for feedback control are limited in the range of vibrations they can accurately detect due to the orientation of magnetic fields remaining constant when the second magnet moves above or below the sensor, and the detection output decreases with distance, making accurate detection difficult and costly with rare earth metals.
Innovation Solution
A speaker design with two magnetic sensors spaced apart to detect the difference in magnetic fields from a detection magnet, determining the orientation and intensity changes to expand the detection range and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single magnetic sensor is used to detect the second magnet, then the device complexity is low, but the measurement precision and detection range are limited
Solution Approach 1:
The single magnetic sensor is divided into two separate magnetic sensors (first magnetic sensor and second magnetic sensor) spaced apart in the vibration direction. This segmentation allows the system to detect the detection magnet's position both above and below the sensor array, expanding the measurement range and improving detection accuracy through differential measurement of magnetic field changes at different locations.
Solution Approach 2:
The solution transitions from a one-dimensional detection approach (single sensor) to a two-dimensional detection approach (two sensors spaced in the vibration direction). By adding the spatial dimension of sensor separation, the system can distinguish between magnet positions above and below the sensor plane, effectively expanding the detection range without significantly increasing overall system complexity.
2Adaptability or versatility
If the second magnet moves to a distant position above the magnetic sensor, then the vibration range is expanded, but the detection output decreases making accurate detection difficult
Solution Approach 1:
By segmenting the detection into two sensors positioned at different locations along the vibration direction, the system maintains detection sensitivity across a wider range of magnet positions. The differential measurement between the two sensors compensates for the decrease in individual sensor output when the magnet is at distant positions, ensuring reliable detection throughout the expanded vibration range.
3Measurement precision
If measures are taken to enable the second magnet to emit a greater amount of magnetism, then the detection output is improved, but the cost increases due to rare earth metals
Solution Approach 1:
The patent introduces a first magnet as an intermediary that generates a magnetic flux in the gap to which the voice coil is exposed. This first magnet works in conjunction with the detection magnet (second magnet) to create a composite magnetic field that enhances the detection output. By using this intermediary magnetic field, the system achieves improved detection sensitivity without requiring the detection magnet itself to be made from expensive rare earth metals, thus controlling material costs while maintaining measurement precision.
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 speaker can accurately detect the position of the vibrating part over a wider range, reducing the need for rare earth metals and enhancing feedback control for improved sound quality and protection of components.
Implementation Method 1
the magnetic sensor can detect the orientation of the composite magnetic flux combining the magnetic flux of the first magnet and the magnetic flux of the second magnet
Implementation Method 2
A first magnet is provided to impart magnetic flux to the voice coil in a gap
Data Source
AI summary
A speaker includes: a drive-and-support part having a frame; a vibrating part supported by the frame such that the vibrating part is able to vibrate; a magnetic drive part configured to make the vibrating part vibrate; a detection magnet provided in one of the drive-and-support part or the vibrating part; a first magnetic sensor and a second magnetic sensor provided in the other one of the drive-and-support part or the vibrating part, and configured to detect a magnetic field produced by the detection magnet; and a detection circuit configured to determine a difference between a first detection output of the first magnetic sensor and a second detection output of the second magnetic sensor. The first and second magnetic sensors are spaced apart from each other in a direction in which the vibrating part vibrates.