Electrostatic parametric transducer and related methods
An electrostatic ultrasonic transducer includes a first conductive layer; a second conductive layer spaced apart from the first conductive layer; and a third conductive layer disposed between the first and second conductive layers, the third conductive layer being spaced apart from the first conductive layer and in physical contact with a part of the second conductive layer.
1. An ultrasonic transducer, comprising:
a first conductive element comprising first and second major surfaces;
a second conductive element comprising first and second major surfaces and textural features formed on the first major surface of the second conductive element and arranged in spaced apart relation to the first conductive element with the first major surface of the second conductive element facing toward the first conductive element; and
a third conductive element comprising first and second major surfaces and positioned between the first and second conductive elements such that the third conductive element does not contact the first conductive element and the second major surface of the third conductive element physically contacts at least some of the textural features of the second conductive element and forms a resonant cavity, wherein the third conductive element comprises an insulating layer and a conducting layer and wherein the third conductive element is oriented such that the insulating layer is disposed between the conducting layer and the second conductive element.
2. The ultrasonic transducer of claim 1 , wherein the ultrasonic transducer has a resonant frequency and wherein the resonant frequency is defined by a volume of the open area between the second and third conductive elements.
3. The ultrasonic transducer of claim 2 , wherein the resonant frequency is further defined by a tension, thickness and density of the third conductive element.
4. The ultrasonic transducer of claim 1 , wherein the textural features comprise a plurality of ridges extending beyond the first major surface of the second conductive element.
5. The ultrasonic transducer of claim 4 , wherein the ridges may comprise at least one of a triangular, square, rectangular, rounded or hemispherical cross-section.
6. The ultrasonic transducer of claim 4 , wherein the ridges span part or all of the length or width of the second conductive element.
7. The ultrasonic transducer of claim 1 , wherein the textural features comprise a plurality of spacers disposed on the first major surface of the second conductive element.
8. The ultrasonic transducer of claim 7 , wherein the second conductive element comprises a conductive layer and an insulating layer, and the spacers comprise a plurality of dots disposed on the insulating layer of the second conductive element.
9. The ultrasonic transducer of claim 1 , wherein the textural features comprise a plurality of dots disposed on the second conductive element.
10. The ultrasonic transducer of claim 8 or 9 , wherein the dots comprise patterns of at least one of spherical, elongated, squared, polygonal, pyramidal, or hemispherical shapes.
11. The ultrasonic transducer of claim 1 , wherein the first conductive element is transparent to ultrasonic signals.
12. The ultrasonic transducer of claim 1 , wherein the first conductive element is sufficiently transparent to ultrasonic signals so as to not attenuate ultrasonic signals generated by the third conductive element by greater than 3 DB.
13. The ultrasonic transducer of claim 1 , wherein the first conductive element is transparent to ultrasonic signals and the second conductive element is not transparent to ultrasonic signals such that, in operation, an ultrasonic signal is emitted from the ultrasonic audio transducer in one direction.
14. The ultrasonic transducer of claim 1 , wherein the ultrasonic transducer is an ultrasonic audio transducer.
15. An ultrasonic transducer, comprising:
a first conductive element comprising first and second major surfaces;
a second conductive element comprising first and second major surfaces and arranged in spaced apart relation to the first conductive element with the first major surface of the second conductive element facing toward the first conductive element; and
a third conductive element comprising first and second major surfaces and positioned between the first and second conductive elements, wherein the third conductive element comprises an insulating layer and a conducting layer and wherein the third conductive element is oriented such that the insulating layer is disposed between the conducting layer and the second conductive element; and
a plurality of first spacers disposed between the second and third conductive elements and configured in touching relation to the second and third conductive elements.
16. The ultrasonic transducer of claim 15 , further comprising a plurality of second spacers disposed between the first and third conductive elements and configured in touching relation to the first and third conductive elements.
17. The ultrasonic transducer of claim 15 , wherein the ultrasonic audio transducer has a resonant frequency and wherein the resonant frequency is defined by a volume of the open area between the second and third conductive elements.
18. The ultrasonic transducer of claim 17 , wherein the resonant frequency is further defined by a tension, thickness and density of the third conductive element.
19. The ultrasonic transducer of claim 15 , wherein the first spacers comprise a plurality of dots disposed on the second conductive element.
20. The ultrasonic transducer of claim 15 , wherein the second spacers comprise a plurality of dots disposed on the first conductive element.
21. The ultrasonic transducer of claim 15 , wherein the first spacers comprise a plurality of dots disposed on one side of the third conductive element.
22. The ultrasonic transducer of claim 21 , wherein the second spacers comprise a plurality of dots disposed on the opposite side of the third conductive element.
23. The ultrasonic transducer of claim 15 , wherein the first spacers comprise a plurality of dots disposed on both sides of the third conductive element.
24. The ultrasonic transducer of claim 15 , wherein the second conductive element comprises a conductive layer and an insulating layer, and the spacers comprise a plurality of dots disposed on the insulating layer of the second conductive element.
25. The ultrasonic transducer of claim 15 , wherein the second conductive element comprises a conductive layer and an insulating layer, and the spacers comprise a plurality of dots disposed in touching relation with the insulating layer of the second conductive element.
26. The ultrasonic transducer of claim 15 , 19 , 20 , 21 , 23 , 24 or 25 wherein the dots comprise patterns of at least one of spherical, elongated, squared, polygonal, pyramidal, or hemispherical shapes.
27. The ultrasonic transducer of claim 15 , wherein the first conductive element is transparent to ultrasonic signals.
28. The ultrasonic transducer of claim 15 , wherein the first conductive element is sufficiently transparent to ultrasonic signals so as to not attenuate ultrasonic signals generated by the third conductive element by greater than 3 DB.
29. The ultrasonic transducer of claim 15 , wherein the first conductive element is transparent to ultrasonic signals and the second conductive element is not transparent to ultrasonic signals such that, in operation, an ultrasonic signal is emitted from the ultrasonic audio transducer in one direction.
30. The ultrasonic transducer of claim 15 , wherein the ultrasonic transducer is an ultrasonic audio transducer.
31. An ultrasonic transducer, comprising:
a transformer comprising first and second inputs and first, second and third outputs, a first winding between the first and second inputs, a second winding between the first and second outputs and a third winding between the second and third outputs;
an ultrasonic audio transducer, comprising:
a first stator electrically connected to the first output of the transformer;
a second stator arranged in spaced apart relation to the first stator and electrically connected to the third output of the transformer;
a conductive element positioned between the first and second stators and electrically connected to the second output of the transformer, the conductive element disposed such that it is at a first spacing from the first stator and a second spacing from the second stator, wherein the second spacing is less than the first spacing and wherein a ratio of the number of turns in the second winding to the number of turns in the third winding is proportional to the first and second spacings; and
a plurality of textural features disposed between and in touching relation to the conductive element and the second stator; and
a bias source coupled between the second output of the transformer and the conductive element.
32. The ultrasonic transducer of claim 31 , wherein the ratio is in the range of 8:1 to 10:1.
33. The ultrasonic transducer of claim 31 , further comprising a resistive element coupled between the bias source and the conductive element.
34. The ultrasonic transducer of claim 31 , wherein the textural features comprise a plurality of ridges extending beyond a first surface of the second stator.
35. The ultrasonic transducer of claim 31 , wherein the ridges may comprise at least one of a triangular, square, rectangular, rounded or hemispherical cross-section.
36. The ultrasonic transducer of claim 31 , wherein the ridges span part or all of the length or width of the second stator.
37. The ultrasonic transducer of claim 31 , wherein the textural features comprise a plurality of spacers disposed on a first surface of the second stator.
38. The ultrasonic transducer of claim 37 , wherein the second stator comprises a conductive layer and an insulating layer, and the spacers comprise a plurality of dots disposed on the insulating layer of the second stator.
39. The ultrasonic transducer of claim 31 , wherein the textural features comprise a plurality of dots disposed on the second stator.
40. The ultrasonic transducer of claim 38 or 39 , wherein the dots comprise patterns of at least one of spherical, elongated, squared, polygonal, pyramidal, or hemispherical shapes.