Bone conduction device having a multilayer piezoelectric element

Abstract

A bone conduction device comprising a multilayer piezoelectric element. The multilayer piezoelectric element comprises two stacked piezoelectric layers, and a flexible passive layer disposed between the piezoelectric layers. The device also comprises a mass component attached to the multilayer piezoelectric element; and a coupling attached to the multilayer piezoelectric element configured to transfer mechanical forces generated by the multilayer piezoelectric element and the mass component to a recipient's skull.

What is claimed is: 
     
       1. A bone conduction device for converting received sounds signals into a mechanical force for delivery to a recipient's skull, the device comprising:
 a plurality of separate, independently operable multilayer piezoelectric elements each comprising two stacked piezoelectric layers, and a passive layer disposed between and mounted to the piezoelectric layers so as to separate the piezoelectric layers from each other, wherein the piezoelectric layers are configured to deform in response to application thereto of electrical signals generated based on the received sound signals; 
 a mass componentone or more mass components attached to one or more of the multilayer piezoelectric elements so as to move in response to deformation of the one or more piezoelectric elements; and 
 a coupling configured to attach the device to the recipient so as to transfer mechanical forces generated by the multilayer piezoelectric element and the mass component to the recipient's skull, 
 wherein the device is configured to apply an electric signal to a first of the plurality of multilayer piezoelectric elements in response to receipt of a high frequency sound signal by the device, and wherein the device is configured to apply an electric signal to a second of the plurality of multilayer piezoelectric elements in response to receipt of a low frequency sound signal by the device. 
 
     
     
       2. The bone conduction device of  claim 1 , wherein the at least two piezoelectric layers of one or more of the multilayer piezoelectric elements have opposing directions of polarization such that application of electrical signals to both of the layers causes deflection of the piezoelectric element in a single direction. 
     
     
       3. The bone conduction device of  claim 1 , wherein each of the two stacked piezoelectric layers of one or more of the multilayer piezoelectric elements comprise two or more piezoelectric sheets. 
     
     
       4. The bone conduction device of  claim 1 , wherein one or more of the multilayer piezoelectric elements comprises a bimorph piezoelectric element. 
     
     
       5. The bone conduction device of  claim 1 , wherein one or more of the multilayer piezoelectric elements comprises a plurality of adjacent segments configured to be actuated substantially independently. 
     
     
       6. The bone conduction device of  claim 5 , wherein the plurality of adjacent segments comprise three adjacent segments. 
     
     
       7. The bone conduction device of  claim 5 , further comprising a plurality of amplifiers configured to selectively generate electrical signals for delivery to the plurality of adjacent segments. 
     
     
       8. The bone conduction device of  claim 7 , wherein a first of the plurality of amplifiers is configured to generate an electric signal for application to a first of the plurality of segments in response to receipt of a high frequency sound signal by the device, and wherein a second of the plurality of amplifiers is configured to generate an electric signal for delivery to a second of the plurality of segments in response to receipt of a low frequency sound signal by the device. 
     
     
       9. The bone conduction device of  claim 1 , wherein each of the piezoelectric layers comprise piezoelectric strips. 
     
     
       10. The bone conduction device of  claim 1 , wherein each of the piezoelectric layers comprise piezoelectric disks. 
     
     
       11. The bone conduction device of  claim 1 , wherein the mass component one or more mass components comprises a plurality of separate mass components attached at different locations of the one or more piezoelectric elements. 
     
     
       12. The bone conduction device of  claim 11 , wherein the plurality of mass components are separated by a vibration damping element. 
     
     
       13. The bone conduction device of  claim 1 , wherein the mass components one or more mass components comprise the passive layer disposed between the piezoelectric layers. 
     
     
       14. A bone conduction device for converting received sound signals into a mechanical force for delivery to a recipient's skull, the device comprising:
 a multilayer piezoelectric element comprising two stacked piezoelectric layers separated from each other by a non-conductive passive layer, wherein the piezoelectric layers have opposing directions of polarization such that application of electric signals, generated based on the sound signals, to both of the layers causes deflection of the piezoelectric element in a single direction and wherein the multilayer piezoelectric element comprises a plurality of adjacent segments configured to be actuated substantially independently; 
 a plurality of amplifiers configured to selectively generate electrical signals for application to the plurality of adjacent segments; 
 a mass componentone or more mass components attached to the multilayer piezoelectric element so as to move in response to deformation of the piezoelectric element; and 
 a coupling configured to attach the device to the recipient so as to transfer mechanical forces generated by the multilayer piezoelectric element and the mass component to the recipient's skull. 
 
     
     
       15. The bone conduction device of  claim 14 , wherein each of the two stacked piezoelectric layers comprise two or more piezoelectric sheets. 
     
     
       16. The bone conduction device of  claim 14 , wherein the multilayer piezoelectric element comprises a bimorph piezoelectric element. 
     
     
       17. The bone conduction device of  claim 14 , wherein the plurality of adjacent segments comprise three adjacent segments. 
     
     
       18. The bone conduction device of  claim 14 , wherein a first of the plurality of amplifiers is configured to generate an electric signal for application to a first of the plurality of segments in response to receipt of a high frequency sound signal by the device, and wherein a second of the plurality of amplifiers is configured to generate an electric signal for application to a second of the plurality of segments in response to receipt of a low frequency sound signal by the device. 
     
     
       19. The bone conduction device of  claim 14 , wherein each of the piezoelectric layers comprise piezoelectric strips. 
     
     
       20. The bone conduction device of  claim 14 , wherein each of the piezoelectric layers comprise piezoelectric disks. 
     
     
       21. The bone conduction device of  claim 14 , wherein the at least one mass component one or more mass components comprises a plurality of separate mass components attached at different locations of the one or more piezoelectric elements. 
     
     
       22. The bone conduction device of  claim 21 , wherein the plurality of mass components are separated by a vibration damping element. 
     
     
       23. The bone conduction device of  claim 14 , wherein the mass components one or more mass components comprise the passive layer disposed between the piezoelectric layers. 
     
     
       24. The bone conduction device of  claim 14 , further comprising:
 a plurality of separate, independently operable multilayer piezoelectric elements. 
 
     
     
       25. The bone conduction device of  claim 24 , wherein the device is configured to apply an electric signal to a first of the plurality of multilayer piezoelectric elements in response to receipt of a high frequency sound signal by the device, and wherein the device is configured to apply an electric signal to a second of the plurality of multilayer piezoelectric elements in response to receipt of a low frequency sound signal by the device.