Magnetoresistive Microphone Package Magnetic Shielding
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Solution Overview
Problem
Microphone packages based on magnetoresistive effect elements face interference from external magnetic fields, such as geomagnetism, which act as noise and affect the accuracy of pressure sensing.
Innovation Solution
The microphone package design incorporates a cover with magnetic and non-magnetic side portions that form a magnetic closed circuit, blocking external magnetic fields and reducing noise interference, while using a resin material for the cover to enhance acoustic performance and mechanical robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetoresistive effect element is used for pressure sensing, then pressure sensing capability is achieved, but external magnetic fields act as noise and degrade measurement precision
Solution Approach 1:
A magnetic shielding layer is introduced as an intermediary between the external magnetic field and the magnetoresistive effect element. This shielding layer selectively blocks external magnetic field lines from reaching the sensing element, while allowing the device to continue functioning normally. The shielding layer acts as a mediator that filters out harmful magnetic interference without affecting the pressure sensing capability.
Solution Approach 2:
The patent utilizes the magnetic properties of materials to convert the harmful effect of external magnetic fields into a beneficial shielding mechanism. By strategically placing magnetic shielding layers, the external magnetic fields that would otherwise cause noise are redirected and contained, effectively protecting the magnetoresistive effect element while maintaining the overall device functionality.
2Measurement precision
If a magnetic shielding structure is added to block external magnetic fields, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Instead of providing uniform magnetic shielding throughout the entire device, the patent applies magnetic shielding materials only in specific locations where external magnetic fields would most strongly affect the magnetoresistive effect element. This localized approach to shielding reduces the overall amount of shielding material needed and simplifies the device structure while still achieving effective magnetic field blocking where it is most critical.
Solution Approach 2:
The magnetic shielding structure is divided into multiple separate segments or layers rather than using a single monolithic shielding component. This segmentation allows for easier integration with the existing device architecture, simplifies manufacturing processes, and enables the shielding to be added in a modular fashion without requiring complete redesign of the entire device 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
This design effectively suppresses external magnetic noise, improving the signal-to-noise ratio and enhancing the acoustic and mechanical performance of the microphone package.
Implementation Method 1
A magnetoresistive effect element can be used to configure a pressure sensing element. This makes it possible to sense pressure change based on the change of the angle between the magnetization of the magnetization free layer and the magnetization of the reference layer.
Implementation Method 2
the side portion is magnetic and provided depending on the first magnetization and the second magnetization. The cover houses therein the pressure sensing element
Data Source
AI summary
According to one embodiment, a microphone package includes: a pressure sensing element including a film and a device; and a cover. The film generates strain in response to pressure. The device includes: a first electrode; a second electrode; and a first magnetic layer. The first magnetic layer is provided between the first electrode and the second electrode and has a first magnetization. The cover includes: an upper portion; and a side portion. The side portion is magnetic and provided depending on the first magnetization and the second magnetization.