Push-push multiple magnetic air gap transducer

An electromagnetic transducer comprising:

• a pole plate including a pole piece and a back plate;
• a first drive plate defining a first drive magnetic air gap between the first drive plate and the pole piece;
• a first drive magnet magnetically coupled to, and positioned between, the back plate and the first drive plate;
• a magnetic material member magnetically coupled to the first drive plate opposite the first drive magnet;
• a second drive plate defining a second drive magnetic air gap between the second drive plate and the pole piece, and disposed between the bucking magnet and the magnetic material member;
• a bucking magnet magnetically coupled to the first drive plate and positioned on an opposite side of the first drive plate from the first drive magnet, and having its polarity opposite that of the first drive magnet;
• a bucking plate magnetically coupled to the bucking magnet and positioned on an opposite side of the bucking magnet from the first drive plate, and defining a non-driving magnetic air gap to provide a low reluctance return path from the pole piece to the bucking magnet;
• a diaphragm assembly including a diaphragm, a bobbin coupled to the diaphragm, a first voice coil coupled to the bobbin and disposed in the first drive magnetic air gap, voice coil windings coupled to the bobbin and disposed in the second drive magnetic air gap, wherein the diaphragm assembly is substantially electromagnetically inert within the non-driving magnetic air gap.

A electromagnetic transducer comprising:

• a cup;
• a first drive magnet disposed within and magnetically coupled to the cup;
• a first drive plate disposed within the cup and magnetically coupled to the first drive magnet, positioned on an opposite side of the first drive magnet from the cup, and defining a first drive magnetic air gap between the first drive plate and the cup;
• a second drive plate disposed within the cup and magnetically coupled to, and positioned between, the bucking magnet and the first drive plate, and defining a second drive magnetic air gap between the second drive plate and the cup;
• a bucking magnet disposed within the cup and magnetically coupled to the first drive plate, and having its magnetic polarity opposite that of the first drive magnet;
• a bucking plate disposed substantially within the cup and magnetically coupled to the bucking magnet, and disposed on an opposite side of the bucking magnet from the first drive plate, and defining a non-driving magnetic air gap to provide a low reluctance return path from the cup to the bucking magnet;
• and
• a diaphragm assembly including a diaphragm, a bobbin coupled to the diaphragm, a first voice coil coupled to the bobbin and disposed in the first drive magnetic air gap, and voice coil windings coupled to the bobbin and disposed in the second drive magnetic air gap, wherein the diaphragm assembly is substantially electromagnetically inert within the non-driving magnetic air gap.

A method of operating an audio speaker, the method comprising:

• A) conducting first magnetic flux in a first magnetic circuit
• i) from a first drive magnet,
• ii) through a first drive plate,
• iii) in a first direction across a voice coil disposed within a first drive magnetic air gap,
• iv) through a magnetically conductive member which comprises one of a cup and a pole plate, and
• v) back to the first drive magnet;
• B) conducting second magnetic flux in a second magnetic circuit
• i) from a bucking magnet,
• ii) through a second drive plate,
• iii) in the first direction across a voice coil disposed within a second drive magnetic air gap,
• iv) through the magnetically conductive member,
• v) across a non driving magnetic air gap in a second direction opposite the first direction without passing through a voice coil,
• vi) through a bucking plate, and
• vii) back to the bucking magnet;
• and
• C) conducting an alternating current electrical signal through the voice coil to move a bobbin coupled to the voice coil, and a diaphragm coupled to the bobbin, by electromagnetic action in the drive magnetic air gap(s) only.

An audio speaker comprising:

• (A) a magnetically conductive member;
• (B) at least two magnet/plate pairs each including,
• (i) a drive magnet having its magnetic poles oriented in a first direction with respect to the magnetically conductive member,
• (ii) a magnetic drive plate magnetically coupled to the drive magnet opposite the magnetically conductive member, and
• (iii) a magnetic drive air gap defined between the magnetic drive plate and the magnetically conductive member;
• wherein
• (a) the magnet of a bottom-most magnet/plate pair is magnetically coupled to the magnetically conductive member, and
• (b) the magnet of each magnet/plate pair which is not the bottom-most, is magnetically coupled to the magnetic drive plate of a next lower magnet/plate pair;
• (C) a bucking magnet magnetically coupled to a top-most magnetic drive plate opposite the magnet/plate pair(s) and having its magnetic poles oriented in a second direction with respect to the magnetically conductive member, wherein the second direction is substantially opposite the first direction;
• (D) a return path plate magnetically coupled to the bucking magnet opposite the magnet/plate pair(s) and defining a non-driving magnetic air gap to provide a low reluctance return path between the bucking magnet and the magnetically conductive member;
• and
• (E) a diaphragm assembly mechanically coupled to the magnetically conductive member and including,
• (i) a diaphragm,
• (ii) a bobbin coupled to the diaphragm, and
• (iii) at least one voice coil coupled to the bobbin to reside in the magnetic drive air gap(s) and to stay out of the non-driving magnetic air gap during linear excursion of the diaphragm assembly.

An electromagnetic transducer comprising:

• an internal permanent magnet;
• at least one internal soft magnet magnetically coupled to the internal permanent magnet;
• an external permanent magnet;
• at least one external soft magnet magnetically coupled to the external permanent magnet;
• at least one drive magnetic air gap defined between one of the internal soft magnet(s) and one of the external soft magnet(s), wherein magnetic flux over each of the drive magnetic air gap(s) is in a same direction;
• a low reluctance return path magnetic air gap defined between one of the internal soft magnet(s) and one of the external soft magnet(s), wherein magnetic flux over the low reluctance return path magnetic air gap is in a second direction substantially opposite the first direction;
• and
• a voice coil assembly including a bobbin and electrically conductive windings coupled to the bobbin in a position wherein the windings do not enter the low reluctance return path magnetic air gap during linear excursion of the voice coil assembly.