Electromagnetic transducer having a low reluctance return path
AssigneeSTEP Technologies, Inc.
InventorEnrique M. Stiles
Life of this patent
Estimating the term…
Abstract
An electromagnetic transducer, such as an audio speaker, includes a return path member which is a pole piece for external magnet geometries or a cup for internal magnet geometries. The magnetic flux return path for the primary drive magnet is through a first portion of the return path member. A first section of a low reluctance magnetic flux return path for a secondary drive magnet is through a second portion of the return path member. A magnetically conductive plate provides a second section of the low reluctance return path from the second portion of the return path member to the secondary drive magnet.
Claims13
An electromagnetic transducer comprising:
- a cup including a back plate portion and a substantially cylindrical wall portion;
- a first magnet magnetically coupled to the back plate portion of cup;
- a first drive plate magnetically coupled to the first magnet opposite the back plate portion of the cup, the first drive plate defining a first drive magnetic air gap with the wall portion of the cup;
- a second magnet magnetically coupled to the first drive plate opposite the first magnet, and having a magnetic polarity substantially opposite a magnetic polarity of the first magnet;
- a return path plate magnetically coupled to the second magnet opposite the first drive plate, and defining a low reluctance return path gap with the wall portion of the cup;
- wherein magnetic flux flows over the return path gap in an orientation substantially opposite that of flux flowing over the first drive magnetic air gap.
An electromagnetic transducer comprising:
- a magnetically conductive cup including a back plate portion and a cylindrical wall portion;
- a first internal magnet magnetically disposed within the cup and magnetically coupled to the bask plate portion of the cup;
- a first drive plate disposed within the cup and magnetically coupled to the first internal magnet opposite the back plate portion of the cup, the first drive plate defining a first drive magnetic air gap with the cylindrical wall portion of the cup;
- a non-magnetically conductive spacer disposed within the cup and coupled to the first drive plate opposite the first internal magnet;
- a second drive plate disposed within the cup and coupled to the spacer opposite the first drive plate, the second drive plate defining a second drive magnetic air gap with the cylindrical wall portion of the cup;
- a second internal magnet disposed within the cup and magnetically coupled to the second drive plate opposite the spacer;
- and
- a return path plate disposed within the cup and magnetically coupled to the second internal magnet opposite the second drive plate, the return path plate defining a low reluctance return path gap with the cylindrical wall portion of the cup;
- wherein the first and second internal magnets are substantially oppositely polarized;
- and
- wherein magnetic flux flows in a same direction over the first and second drive magnetic air gaps, and in a substantially opposite direction over the low reluctance return path gap.
An electromagnetic transducer comprising:
- a magnetically conductive cup including a back plate portion and a cylindrical wall portion;
- a first magnet disposed within the cup and magnetically coupled atop the back plate portion of the cup;
- a return path plate disposed within the cup so as to define a low reluctance return path gap with the cylindrical wall portion of the cup;
- a second magnet disposed within the cup and magnetically coupled beneath the return path plate, the second magnet polarized substantially oppositely the first magnet;
- at least one drive plate disposed within the cup and defining a corresponding number of drive magnetic air gap(s) with the cylindrical wall portion of the cup, wherein a lowermost one of the drive plate(s) is magnetically coupled atop the first magnet and an uppermost one of the drive plate(s) is magnetically coupled beneath the return path plate;
- and
- at least one voice coil disposed in the drive magnetic air gap(s).
Dependencies are inferred from the claim text.