Moving coil module comprising a substrate patterned with a conductor trace
A linear moving coil magnetic drive system includes a continuous loop coil of flat, thin, rigid construction which levitates inside a quadrupole permanent magnet assembly with minimum gap. The linear coil may be a flat, racetrack-shaped, continuous loop, which may be constructed with single or multilayers PCB, flex-circuit, or other membrane process. The linear coil may include a coating of permeable magnetic material along the insulated conductor traces. The linear coil may be sandwiched between carbon fiber fabrics and cured to create a long, flat, thin and perfectly straight, extremely stiff, light-weight, load-bearing tee-shaped structure. This structure is levitated inside a quadrupole permanent magnetic assembly with minimum air gap between the high gauss magnets. In additional to the bare conductor traces inside this coil, also integrated into this PCB structure, is simple second-order equalizer electronic circuitry, comprised of surface-mounted resistors, capacitors, and IC chips. Either a close loop or open loop control may be included to tune the voltage amplitude at the resonance frequency of this magnetic drive system.
1. A loudspeaker comprising:
a diaphragm configured to vibrate to create sounds;
a magnet assembly comprising a plurality of magnets and an air gap between the magnets; and
a moving coil module comprising an electrically insulating substrate that is patterned with an electrically conducting material forming a coil shaped conductor trace thereon, wherein the substrate and the conductor trace are located in the air gap between the magnets and the moving coil module is attached to the diaphragm and the substrate extends from a surface of the diaphragm,
wherein the moving coil module further comprises two or more ferromagnetic strips that contact the conductor trace, and wherein the two or more ferromagnetic strips, the conductor trace, and the electrically insulating substrate are encapsulated by a non-conductive cover that provides attachment of the coil module to the diaphragm.
2. The loudspeaker of claim 1 wherein the magnet assembly includes a plurality of T-shaped magnet support frames, and the plurality of magnets are supported by the magnet support frames.
3. The loudspeaker of claim 2 wherein the magnet assembly includes a pair of T-shaped magnet support frames, and each T-shaped magnet support frame supports at least two longitudinal rows of magnets.
4. The loudspeaker of claim 3 wherein magnets in a first row of magnets of the at least two longitudinal rows have a polarity opposite polarity of magnets in a second row of magnets of the at least two longitudinal rows.
5. The loudspeaker of claim 3 wherein each of the pair of T-shaped magnet support frames comprises a first planar portion and a second planar portion substantially orthogonal to the first planar portion, wherein the at least two longitudinal rows of magnets are attached to a surface of the first planar portion opposite a surface of the first planar that comes into contact with the second planar portion.
6. The loudspeaker of claim 1 wherein the substrate is a printed circuit board (PCB) substrate.
7. The loudspeaker of claim 6 wherein the conductor trace is etched or printed onto, or embedded or partially embedded into the PCB substrate.
8. The loudspeaker of claim 6 wherein the PCB board is formed from flexible or semi-rigid materials.
9. The loudspeaker of claim 1 wherein the conductor trace is formed of metallized trace lines forming a racetrack shaped coil layout.
10. The loudspeaker of claim 1 wherein the conductor trace has a variable cross section area along the length of the conductor trace.
11. The loudspeaker of claim 1 wherein a conductive material coating is added to the conductor trace, thereby decreasing impedance of the conductor trace.
12. The loudspeaker of claim 1 wherein at least a single layer of the conductor trace is provided to form the coil, and wherein the conductor trace does not intersect itself.
13. The loudspeaker of claim 1 wherein the two or more ferromagnetic strips are positioned so that they are not in contact with one another.
14. The loudspeaker of claim 13 wherein the two or more ferromagnetic strips are aligned substantially parallel to one another.
15. The loudspeaker of claim 1 wherein the two or more ferromagnetic strips contact the conductor trace on a side opposite the substrate.
16. A method of forming a moving coil module for a loudspeaker having a diaphragm configured to vibrate to create sounds, a magnet assembly comprising a plurality of magnets and an air gap between the magnets, and the moving coil module in the air gap and attached to the diaphragm, said method comprising:
selecting a desired characteristic of a magnetic field that includes the magnets;
providing an electrically insulating substrate dimensioned based on the selected desired characteristic of the magnetic field;
selecting dimensions and an arrangement of an electrically conducting material forming a coil shaped conductor trace based on the selected desired characteristic of the magnetic field;
patterning the electrically insulating substrate with the conductor trace thereon in accordance with the selected dimensions and arrangement; and
providing two or more ferromagnetic strips contacting the conductor trace, wherein the two or more ferromagnetic strips, the conductor trace, and the electrically insulating substrate are encapsulated by a non-conductive cover.
17. The method of claim 16 wherein the electrically insulating substrate is a printed circuit board (PCB) substrate and further comprising etching, printing, embedding, or partially embedding the conductor trace on the PCB substrate.
18. The method of claim 17 further comprising encapsulating the PCB substrate and the conductor trace in the non-conductive cover; and baking the PCB substrate, conductor trace, and non-conductive cover at a temperature of least 100 degrees C.
19. The method of claim 16 wherein the conductor trace is patterned to form a racetrack coil that forms a single layer and does not intersect itself.
20. The method of claim 19 wherein the conductor trace is patterned to provide selected spacing between each wind of the coil.