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US 5,357,587 AGranted
Distortion reduction in loudspeakers
OwnerRobert M. Grodinsky, David G. Cornwellinventors
Life of this patent
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Abstract
A loudspeaker includes a pole piece that is transversely divided into magnetically coupled, but electrically isolated first and second sections. The first pole piece section is surrounded by the voice coil and is magnetically coupled to, but electrically isolated from, the loudspeaker bottom plate. Other versions include pairs of loudspeakers with reversed polarity magnets and magnetic intercoupling for offsetting distortion produced therein.
Claims17
A loudspeaker system comprising:
- a magnetic structure including a permanent magnet, a magnetically permeable pole piece and first and second magnetically permeable plates for developing a unidirectional magnetic field in an air gap between said pole piece and said first magnetically permeable plate;
- an AC signal carrying voice coil mounted for movement in said air gap, said voice coil undesirably generating distortion producing AC energy in the form of AC magnetic flux and eddy currents in said magnetic structure;
- and
- means dividing said magnetically permeable pole piece into at least first and second pole piece sections that are electrically isolated for reducing the distortion effects of said AC energy, said second pole piece section being physically directly connected to said second magnetically permeable plate.
1 more element
A loudspeaker system comprising:
- a magnetic structure including a permanent magnet, a magnetically permeable pole piece and first and second magnetically permeable plates for developing a unidirectional magnetic field in an air gap between said magnetically permeable pole piece and said first magnetically permeable plate;
- an AC signal carrying voice coil mounted for movement in said air gap, said voice coil undesirably generating distortion producing AC energy in the form of magnetic flux and eddy currents in said magnetic structure;
- means dividing said magnetically permeable pole piece into electrically isolated first and second pole piece sections for reducing the distortion effects of said AC energy;
- and
- a magnetically permeable extension piece magnetically coupled to said first pole piece section.
2 more elements
A loudspeaker system comprising:
- first magnetic structure means including a first permanent magnet, a first magnetically permeable pole piece divided into two electrically isolated sections for developing a unidirectional magnetic field in an air gap;
- a first AC signal carrying voice coil mounted for movement in said air gap, said first voice coil undesirably generating distortion producing AC energy in the form of magnetic flux and eddy currents in said first magnetic structure means;
- second magnetic structure means having a second permanent magnet oppositely poled with respect to said first permanent magnet, a second AC voice coil arranged to move in the same direction as said first AC voice coil in response to the same polarity of AC signal and a second magnetically permeable pole piece divided into two electrically isolated sections;
- and
- a first magnetically permeable member coupling corresponding ones of said isolated pole piece sections for offsetting distortion effects in said first and said second magnetic structure means.
2 more elements
Dependencies are inferred from the claim text.