Magnetically self-shielded speaker box for a mobile device
The present document describes techniques for a magnetically self-shielded speaker box for a mobile device. The speaker box described herein includes a thin metal enclosure, thereby reducing or eliminating plastic components from the exterior enclosure of the speaker box. The metal of the enclosure has a high magnetic permeability to prevent penetration of a magnetic field generated by the speaker transducer within the exterior enclosure. Also, the exterior enclosure includes at least two enclosure portions that are joined together with a continuous welded seam. Accordingly, the speaker box described herein is a thin-walled, fully metal, high-permeability enclosure resulting in a smaller, self-shielded solution that reduces both (i) the total physical volume of the speaker box for a given internal speaker back volume and (ii) the spacing requirements to adjacent voice-coil-motor auto-focus camera modules.
1 . A mobile device comprising:
a camera module having a voice coil motor with one or more magnets, the voice coil motor configured to provide an auto-focus functionality for the camera module; and
a microspeaker module located in proximity to the camera module within a range of 0.5 to 3.5 millimeters, the microspeaker module including:
a magnetically self-shielded speaker box; and
a speaker driver housed within the magnetically self-shielded speaker box.
2 . The mobile device of claim 1 , wherein:
the mobile device is a smartphone;
the microspeaker module is an earpiece speaker for the mobile device; and
the camera module is a front-facing camera or a rear-facing camera.
3 . The mobile device of claim 1 , wherein:
the mobile device has first, second, and third axes, the first axis corresponding to a length, the second axis corresponding to a width, the third axis corresponding to a depth, the length greater than the width, the width greater than the depth;
the third axis intersects front and rear sides of the mobile device;
the microspeaker module has a front side for providing a frontward sound wave and a rear side for providing a backward sound wave; and
the front side of the microspeaker module faces a back of a display of the mobile device.
4 . The mobile device of claim 1 , further comprising:
one or more antennas; and
an additional microspeaker module located proximate to the one or more antennas, the additional microspeaker module having a low magnetic permeability that is less than 100 Henry per meter.
5 . The mobile device of claim 1 , wherein the speaker driver is a 10 millimeter by 12 millimeter transducer.
6 . The mobile device of claim 1 , further comprising one or more additional camera modules located in proximity to the microspeaker module within a range of 0.5 to 3.5 millimeters, wherein the one or more additional camera modules are rear-facing cameras.
7 . The mobile device of claim 1 , wherein:
the magnetically self-shielded speaker box includes an enclosure having a high magnetic permeability that is greater than 500 Henry per meter to reduce penetration of a magnetic field through the enclosure; and
the speaker driver is configured to generate audio signals and the magnetic field in a back volume, the back volume being an empty volume between the speaker driver and an interior surface of the enclosure.
8 . The mobile device of claim 7 , wherein the speaker driver is supported within the enclosure of the magnetically self-shielded speaker box by a plastic internal bracket.
9 . The mobile device of claim 7 , wherein the enclosure defines an opening in a wall of the enclosure for passage of frontward sound waves output by the speaker driver.
10 . The mobile device of claim 9 , further comprising a pressure-sensitive adhesive audio seal disposed on an exterior surface of the wall of the enclosure.
11 . The mobile device of claim 10 , further comprising conductive pressure-sensitive adhesive disposed on the exterior surface of the wall for grounding.
12 . The mobile device of claim 7 , wherein the enclosure has a magnetic permeability in a range of 600 to 1100 Henry per meter.
13 . The mobile device of claim 7 , wherein the enclosure is made of stainless steel.
14 . The mobile device of claim 7 , wherein the enclosure includes at least two enclosure members joined together by a continuous welded seam.
15 . The mobile device of claim 7 , wherein the enclosure includes a thickness that is within a range of 0.3 mm to 0.1 mm.
16 . The mobile device of claim 7 , wherein the enclosure includes a vent, the vent configured to equalize pressure between an exterior of the enclosure and an interior of the enclosure.
17 . An electronic device comprising:
a camera module having a voice coil motor with one or more magnets, the voice coil motor configured to provide an auto-focus functionality for the camera module; and
a microspeaker module located in proximity to the camera module within a range of 0.5 to 3.5 millimeters, the microspeaker module including:
a transducer configured to generate audio signals and a transducer-generated magnetic field; and
a magnetically self-shielded speaker box, the magnetically self-shielded speaker box including walls forming a speaker enclosure, the speaker enclosure housing the transducer in a manner that includes an empty volume between a rear of the transducer and an interior surface of the speaker enclosure, the magnetically self-shielded speaker box configured to reduce magnetic flux of the transducer-generated magnetic field from penetrating beyond the walls of speaker enclosure.
18 . The electronic device of claim 17 , wherein the speaker enclosure includes a high magnetic permeability that is greater than 500 Henry per meter and a thickness that is within a range of 0.3 mm to 0.1 mm.
19 . The electronic device of claim 17 , wherein the speaker enclosure defines an opening in one of the walls of the enclosure for passage of frontward sound waves output by the transducer.
20 . The electronic device of claim 17 , wherein:
the electronic device is a smartphone;
the microspeaker module is an earpiece speaker for the electronic device; and
the camera module is a front-facing camera or a rear-facing camera.