Audio speaker with graduated voice coil windings
AssigneeSTEP Technologies, Inc.
InventorsEnrique M. Stiles, Richard C. Calderwood
Life of this patent
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Abstract
An audio speaker driver having a voice coil with graduated windings such that different sections of the voice coil have different electrical resistances and/or lengths per unit of height of the voice coil. A center portion of the voice coil gives a greater BL, while outer portions give lower overall electrical resistance, such that the audio speaker driver is highly efficient and linear during low excursion operation, with a smoother transition from the linear region to the grossly non-linear region. The wire of the graduated voice coil can have varying cross-sectional area over its length, can be wound on varying on-center spacing, can be wound in different numbers of layers in the various sections, and/or it can fork into interlaced, parallel windings.
Claims25
An audio speaker driver comprising:
- (A) a motor structure having a magnetic circuit including a magnetic air gap;
- and
- (B) a voice coil assembly disposed within the magnetic air gap and including,
- (1) a bobbin, and
- (2) a voice coil coupled to the bobbin, wherein the voice coil includes,
- (a) a center set of voice coil windings of wire wound about a center portion of the bobbin, and
- (b) an outer set of voice coil windings of wire wound about outer portions of the bobbin above and below the center portion,
- (c) wherein in at least one of,
- (i) the center set of voice coil windings has a higher average electrical resistance per unit of voice coil height than the outer set of voice coil windings, and
- (ii) the center set of voice coil windings has a longer average length L per unit of voice coil height than the outer set of voice coil windings.
An audio speaker driver comprising:
- a magnetic circuit including a magnetic air gap;
- and
- a voice coil assembly disposed within the magnetic air gap and including,
- a bobbin,
- center voice coil windings of wire having a first spacing, arid
- outer voice coil windings of wire above and below the center voice coil windings and having a second spacing looser than the first spacing.
A voice coil assembly for use in an audio speaker driver, the voice coil assembly comprising:
- a bobbin;
- and
- a wire wound around the bobbin into,
- a center portion having a first on-center spacing, and
- an outer portion at least one of above and below the center portion and having a second on-center spacing looser than the first on-center spacing.
A method of operating an audio speaker driver, the method comprising:
- conducting magnetic flux over a magnetic air gap in a magnetic circuit including a magnet, a drive plate, and a magnetic return path member;
- and
- conducting an alternating electric current through a voice coil which comprises wire wound in a graduated pattern around a bobbin, wherein the graduated pattern includes upper and lower outer portions, and a center portion wound on tighter on-center spacing than the outer portions.
The method of 23 further comprising:
- in response to the alternating electric current being conducted through the voice coil when the center portion of the voice coil's windings are disposed within the magnetic air gap, moving the voice coil under a first amount of electromotive force;
- and
- in response to the alternating electric current being conducted through the voice coil when one of the upper and lower portions of the voice coil's windings are disposed within the magnetic air gap, moving the voice coil under a second amount of electromotive force lower than the first amount of electromotive force.
The method of 24 further comprising:
- when the center portion of the voice coil's windings are disposed within the magnetic air gap, operating the audio speaker in a substantially linear excursion mode;
- and
- when one of the upper and lower portions of the voice coil's windings are disposed within the magnetic air gap, operating the audio speaker in a mode which is less linear and less efficient than the linear excursion mode.
Dependencies are inferred from the claim text.