Variable stiffness diaphragm for a playback device

1 . A diaphragm for an audio transducer, the diaphragm comprising:

a body having a first surface extending between a radially inner edge and a radially outer edge; and

a second surface of the body opposite the first surface, the second surface extending between the radially inner edge and the radially outer edge,

wherein the body includes a major axis defined as having the longest length across the body and a minor axis defined as having the shortest length across the body, and

wherein a thickness extending between the first surface and the second surface increases along a circumferential axis surrounding a central aperture as it approaches the major axis and the thickness decreases along the circumferential axis as it approaches the minor axis.

2 . The diaphragm of claim 1 , wherein the body comprises an annular body defining the central aperture.

3 . The diaphragm of claim 1 , wherein along a first azimuthal direction, the body has a first range of thicknesses extending between the first surface and the second surface, the first range of thicknesses comprising a first thickness adjacent the radially inner edge and a second thickness adjacent the radially outer edge, the first thickness being different from the second thickness.

4 . The diaphragm of claim 3 , wherein along a second azimuthal direction, the body has a second range of thicknesses extending between the first surface and the second surface, the second range of thicknesses comprising a third thickness adjacent the radially inner edge and a fourth thickness adjacent the radially outer edge, the third thickness being different from the fourth thickness.

5 . The diaphragm of claim 4 , wherein the body is longer along the first azimuthal direction than the second azimuthal direction.

6 . The diaphragm of claim 3 , wherein the first range of thicknesses increases in thickness from the radially inner edge to the radially outer edge along the first azimuthal direction.

7 . The diaphragm of claim 3 , wherein the first range of thicknesses varies nonuniformly in thickness from the radially inner edge to the radially outer edge along the first azimuthal direction.

8 . The diaphragm of claim 4 , wherein the first thickness is smaller than the third thickness.

9 . The diaphragm of claim 4 , wherein the second thickness is smaller than the fourth thickness.

10 . The diaphragm of claim 3 , wherein the first range of thicknesses is at its maximum thickness at a location spaced apart from the radially inner edge and the radially outer edge.

11 . A diaphragm for an audio transducer, the diaphragm comprising:

an annular body defining a central aperture;

a first surface of the body extending between a radially inner edge adjacent the aperture and a radially outer edge; and

a second surface of the body opposite the first surface, the second surface extending between the radially inner edge and the radially outer edge,

wherein along a first azimuthal direction, the body has a first range of stiffnesses extending between the radially inner edge and the radially outer edge, the first range of stiffnesses comprising a first stiffness adjacent the radially inner edge and a second stiffness adjacent the radially outer edge, the first stiffness being different from the second stiffness, wherein a thickness of the body between the first surface and the second surface increases monotonically along the first azimuthal direction from the radially inner edge to the radially outer edge, and

wherein along a second azimuthal direction, the body has a second range of stiffnesses extending between the radially inner edge and the radially outer edge, the second range of stiffnesses comprising a third stiffness adjacent the radially inner edge and a fourth stiffness adjacent the radially outer edge, the third stiffness being different from the fourth stiffness.

12 . The diaphragm of claim 11 , wherein along the second azimuthal direction, the body comprises a range of thicknesses extending between the first surface and the second surface, the range of thicknesses comprising a first thickness adjacent the radially inner edge and a second thickness adjacent the radially outer edge.

13 . The diaphragm of claim 12 , wherein the first thickness is different from the second thickness.

14 . The diaphragm of claim 12 , wherein the first range of stiffnesses is at its maximum stiffness at a location spaced apart from the radially inner edge and the radial outer edge.

15 . The diaphragm of claim 11 , wherein the annular body is conical shaped.

16 . The diaphragm of claim 11 , wherein the annular body comprises plastic.

17 . An audio transducer, comprising:

a frame;

the diaphragm of claim 11 ;

a surround resiliently coupling the radially outer edge of the diaphragm to the frame;

a magnet attached to the frame; and

a voice coil adjacent the magnet and operably coupled to the diaphragm, wherein the voice coil is configured to receive a flow of electric signals from an amplifier, and, in response to the received flow of electric signals, correspondingly move the diaphragm axially inward and outward with respect to the frame, thereby producing sound waves.

18 . The audio transducer of claim 17 , wherein the sound waves have a cutoff frequency between about 3 kilohertz (kHz) and about 7 kHz.

19 . The audio transducer of claim 17 , further comprising a dust cap configured to substantially axially overlap the center aperture.

20 . A playback device, comprising:

an enclosure; and

an audio transducer according to claim 17 , the audio transducer carried by the enclosure.