Apple Wins Patent for a Next-Gen iPhone Audio Speaker that uses Advanced Magnets to Improve Acoustic Performance
The U.S. Patent and Trademark Office officially published a series of 48 newly granted patents for Apple Inc. today. In this particular report we cover a new audio speaker system for the iPhone that increases a magnetic field that may generate a larger mechanical force on the voicecoil to improve acoustic performance while reducing stray magnetic flux that may prevent demagnetization of nearby magnetic strip cards.
Granted Patent: Audio Speaker having a High-Saturation Magnetic Insert
Apple's newly granted patent covers their invention relating to an embodiment related to an audio speaker, which includes a magnetic system having a magnetic insert in a recess of a bottom plate, is disclosed. The magnetic insert may have a higher magnetic saturation level than the bottom plate.
Apple's patent FIG. 9 is a cross-sectional view, taken about line B-B of FIG. 6, of a magnetic system of an audio speaker; FIG. 17 is a flowchart of a method of manufacturing an audio speaker having a high-saturation magnetic insert in a recess of a bottom plate
Apple notes that electronic devices having audio speakers are becoming more compact, and as the form factors of these devices shrink, the space available for the audio speaker also reduces. Accordingly, the size of the magnetic system components must be reduced to fit within the audio speaker enclosure. However, as the magnetic components are miniaturized, e.g., as a top plate or a bottom plate of the magnetic circuit becomes thinner, the thinner magnetic components are unable to contain the applied magnetic field within the component cross-section. That is, when the magnetic field in the thinner component reaches a saturation limit, e.g., when the entire cross-section is saturated by the magnetic field, magnetic flux tends to leak out of the magnetic circuit into a surrounding environment.
In some cases, this stray flux can leak into nearby low coercivity items, e.g., hotel keys, gift cards, and parking tickets. The stray flux may then cause the low coercivity items to demagnetize and lose stored data. Thus, a magnetic system having components with higher saturation limits may allow the magnetic field in the magnetic system to be increased and the stray magnetic flux to be reduced within a compact form factor.
The increased magnetic field may generate a larger mechanical force on the voicecoil to improve acoustic performance of the audio speaker, and the reduced stray magnetic flux may prevent demagnetization of nearby magnetic strip cards.
Apple further notes that the bottom plate of the system may be formed from a magnetic steel material and the magnetic insert may be formed from a high-saturation magnetic material, e.g., an iron-cobalt (FeCo) alloy such as Hiperco, Vacoflux, or similar high permeability FeCo alloys. Thus, the magnetic saturation level of the magnetic insert may be greater, e.g., at least 10% greater, than the magnetic saturation level of the bottom plate. Accordingly, the magnetic insert may form a preferential magnetic flux path from the lateral magnet to the center magnet to contain the magnetic field within the audio speaker.
Apple's granted patent 9,571,936 was originally filed in Q2 2015 and published today by the US Patent and Trademark Office. To review this highly complex invention click here.
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