Communication device using bone conduction
A communication device comprising a microphone, a conduction interface and an electromechanical force transducer mounted to the conduction interface to drive the interface to conduct sound to a user by bone conduction, characterised in that the transducer has an intended operative frequency range and comprises a resonant element having a frequency distribution of modes in the operative frequency range and coupling means for mounting the transducer to the interface.
1. A communication device comprising:
a microphone,
a conduction interface,
an electromechanical force transducer mounted to the conduction interface to drive the interface to conduct sound to a user by bone conduction, wherein the transducer has an intended operative frequency range and comprises a resonant element having a frequency distribution of modes in the operative frequency range, and
a coupler for mounting transducer to the interface, wherein the parameters of the resonant element are selected to enhance the distribution of modes in the resonant element in the operative frequency range, and wherein the distribution of modes in the resonant element has a density of modes which is sufficient for the resonant element to provide an effective mean average force which is substantially constant with frequency.
2. A communication device according to claim 1 , wherein the conduction interface is mounted adjacent a user's mastoid bone.
3. A communication device according to claim 1 , wherein the coupler is attached to the resonant element at a position which is beneficial for coupling modal activity of the resonant element to the interface.
4. A communication device according to claim 1 , wherein the modes are distributed substantially even over the intended operative frequency range.
5. A communication device according to claim 2 , comprising:
a casing having an extension remote from the microphone, the transducer being mounted in the extension whereby in use the transducer is adjacent a user's mastoid bone.
6. A communication device according to claim 1 , wherein the resonant element is modal along two substantially normal axes, each axis having an associated fundamental frequency and the ratio of the two associated fundamental frequencies being adjusted for best modal distribution.
7. A communication device according to claim 6 , wherein the ratio of the two fundamental frequencies is about 9:7.
8. A communication device according to claim 1 , wherein the transducer comprises a plurality of resonant elements each having a distribution of modes, the modes of the resonant element being arranged to interleave in the operative frequency range whereby the distribution of modes in the transducer as a whole device is enhanced.
9. A communication device according to claim 1 , wherein the resonant element is plate-like.
10. A communication device according to claim 1 , wherein the shape of the resonant element is selected from the group consisting of beam-like, trapezoidal, hyperelliptical, generally disc shape and rectangular.
11. A communication device according to claim 1 , wherein the resonant element is plate-like.
12. A communication device according to claim 1 , wherein the shape of the resonant element is selected from the group consisting of beam-like, trapezoidal, hyperelliptical, generally disc shaped and rectangular.
13. A communication device according to claim 1 , wherein the communication device is selected by the group consisting of a telephone, a hearing aid, eyeglasses, and a headset.
14. A communication device comprising:
a microphone,
a conduction interface,
an electromechanical force transducer to the conduction interface to drive the interface to conduct sound to user by bone conduction, wherein the transducer has an intended operative frequency range and comprises a resonant element having a frequency distribution of modes in the operative frequency range, and
a coupler for mounting the transducer to the interface, wherein the resonant element is modal along two substantially normal axes, each axis having an associated fundamental frequencies and the ratio of two associated fundamental frequencies being adjusted for best modal distribution.
15. A communication device according to claim 14 , wherein the ratio of two fundamental frequencies is about 9:7.
16. A communication device comprising:
a microphone,
a conduction interface,
an electromechanical force transducer mounted to the conduction interface to drive the interface to conduct sound to a user by bone conduction, wherein the transducer has an intended operative frequency range and comprises a resonant element having a frequency distribution of modes in the operative frequency range, and
a coupler for mounting the transducer to the interface, wherein the transducer comprises a plurality of resonant elements each having a distribution of modes of the resonant elements being arranged to interleave in the operative frequency range whereby the distribution of modes in the transducer as a whole device is enhanced.