Douglas A Button

US Patent:

6768806, Jul 27, 2004

Filed:

Mar 18, 1999

Appl. No.:

09/271686

Inventors:

Douglas J. Button - Los Angeles CA
Ralph E. Hyde - Santa Clarita CA
Alex V. Salvatti - Northridge CA

Assignee:

Harman International Industries, Incorporated - Northridge CA

International Classification:

H04R 2500

US Classification:

381401, 381396, 381412, 381414

Abstract:

Loudspeakers and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic and higher order even harmonic distortion, a centered location on the flux loop centerline, i. e. centered in the magnetic gap, favors reduction of third harmonic and higher odd order harmonic distortion, while location outside the flux loop as defined by its center line but near the voice coil acts generally to reduce harmonic distortion and reduce the voice coil inductance. Thus a plurality of rings can be strategically deployed at different locations so as to optimally suppress both even and odd order harmonic distortion and to reduce the voice coil inductance.

US Patent:

6847726, Jan 25, 2005

Filed:

Apr 9, 2003

Appl. No.:

10/410005

Inventors:

Douglas J. Button - Los Angeles CA, US
Ralph E. Hyde - Santa Clarita CA, US
Alex V. Salvatti - Northridge CA, US

Assignee:

Harman International Industries, Incorporated - Northridge CA

International Classification:

H04R 2500

US Classification:

381401, 381396, 381412, 381414

Abstract:

Loudspeaker and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic distortion and higher order even harmonic distortion, a centered location on the flux loop centerline, i. e. centered in the magnetic gap, favors reduction of third harmonic and higher odd order harmonic distortion, while location outside the flux loop as defined by its center line but near the voice coil acts to generally reduce harmonic distortion and reduce the voice coil inductance. Thus a plurality of rings can be strategically deployed at different locations so as to optimally suppress both even and odd order harmonic distortion and to reduce the voice coil inductance.

US Patent:

50420720, Aug 20, 1991

Filed:

Apr 14, 1989

Appl. No.:

7/337826

Inventors:

Douglas J. Button - Los Angeles CA

Assignee:

Harman International Industries, Inc. - Northridge CA

International Classification:

H04R 2500

US Classification:

381192

Abstract:

A self-cooled electrodynamic loudspeaker wherein the magnetic structure or pole piece has channels whereby cool air may be introduced and hot air may be exhausted to cool a voice coil by movement of the speaker diaphragm. This self-cooling results in greater power handling and output of the speaker.

US Patent:

58287671, Oct 27, 1998

Filed:

Sep 22, 1997

Appl. No.:

8/934642

Inventors:

Douglas J. Button - Los Angeles CA

Assignee:

JBL Inc. - Northridge CA

International Classification:

H04R 2500

US Classification:

381195

Abstract:

An electro-magnetic loudspeaker, with dual voice coils operating in corresponding magnetic fields in annular gaps between permanent magnet pole pieces, is provided with a single short-circuited braking coil of one or more turns mounted on the voice coil form midway between the two voice coils. The braking coil has minimal effect on normal operation of the loudspeaker, but introduces an inductive braking effect from counter-EMF whenever the voice coil assembly displacement approaches a working limit in either direction, as the braking coil enters a corresponding one of the two magnetized gaps. Thus bidirectional braking/damping is accomplished in a dual coil speaker by the addition of a single braking coil, which could be simply a one turn ring; whereas bidirectional inductive braking in a speaker with a single voice coil requires two such braking coils flanking the voice coil. The single braking/damping coil can be brought out to terminals for connecting it in a loop circuit with an active feedback driver and/or a network of one or more reactive components, for modifying and enhancing the braking/damping action.

US Patent:

49339753, Jun 12, 1990

Filed:

May 19, 1988

Appl. No.:

7/196438

Inventors:

Douglas J. Button - Los Angeles CA

Assignee:

Electro-Voice, Inc. - Buchanan MI

International Classification:

H04R 904
H04R 900
H04R 902
H04R 906

US Classification:

381192

Abstract:

A loudspeaker with a voice coil reciprocally disposed in a magnetic gap provided with means for conducting heat outwardly from the gap comprising a flat circular web disposal in abuttment with the magnetic structure and extending between a cylindrical collar which confronts the voice coil former to a circular ring integral with the frame of the loudspeaker and including vanes extending from the web between the collar and ring. The voice coil former is limited to axial motion by a pair of spaced flat disks mounted at their centers on the central pole piece normal to the axis of motion and on the coil former at their perimeters.