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AssigneeWisdom Audio Corp.
InventorsJack T. Bohlender, Thilo Christian Stompler, David J. Graebener, David J. Michno, Robert M. Smith
Estimating the term…
An audio loudspeaker having an induction motor whose yoke components are formed of powdered iron or other material which is highly magnetically permeable and highly electrically resistive. The oscillating magnetic flux caused by the alternating current applied to the primary coil induces eddy currents in the shorted turn secondary coil but not in the yoke components. This reduces heating of the yoke components, reduces flux modulation, and reduces wasted power.
An electromagnetic transducer comprising:
A loudspeaker induction motor comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Transducers of moving-coil, moving-strip, or moving-wire type: loudspeakers
Details of transducers of the moving-coil, moving-strip, or moving-wire type covered by H04R9/00 but not provided for in any of its subgroups:…
Loudspeakers, microphones, gramophone pick-ups or like acoustic electromechanical transducers
About 3 years 8 months of term left · ends 1 Jul 2030 (estimated)
1. Technical Field of the Invention
This invention relates generally to electromagnetic transducer motor structures, and more specifically to the material composition of the yoke and other steel parts in the magnetic circuit of an induction motor for a transducer such as a loudspeaker or a microphone.
2. Background Art
FIG. 1 shows a cross-section view of one embodiment of an induction motor according to this invention.
FIG. 2 shows a perspective view of the motor of FIG. 1.
FIG. 3 shows an exploded view of the motor of FIG. 2.
The invention will be understood more fully from the detailed description given below and from the accompanying drawings of embodiments of the invention which, however, should not be taken to limit the invention to the specific embodiments described, but are for explanation and understanding only.
FIG. 1 illustrates one embodiment of an induction motor 10 according to this invention. The induction motor includes a magnetically conductive cup 12 having a back plate portion 14, an outer cylinder portion 16, and a polepiece portion 18. The back plate, outer cylinder, and polepiece may be of monolithic construction as shown, or they may be distinct components coupled together. The induction motor further includes a radially charged magnet 22 disposed within the outer cylinder; in the example shown, the radially charged magnet is disposed against and magnetically coupled to the inner surface of the outer cylinder, but in other embodiments, it could be disposed against and magnetically coupled to the outer surface of the polepiece.
The induction motor optionally but advantageously includes a magnetically conductive cap 20 which is disposed against and magnetically couples the upper end of the polepiece and the upper end of the outer cylinder. In the embodiment shown, the cap engages the upper surface of the outer cylinder and the outer surface of the polepiece; in other embodiments, it could engage the inner surface of the outer cylinder and/or the upper surface of the polepiece, instead.