Method and apparatus for producing an acoustic field
The present invention concerns a method and apparatus for the modulation of an acoustic field for providing tactile sensations. A method of creating haptic feedback using ultrasound is provided. The method comprises the steps of generating a plurality of ultrasound waves with a common focal point using a phased array of ultrasound transducers, the common focal point being a haptic feedback point, and modulating the generation of the ultrasound waves using a waveform selected to produce little or no audible sound at the haptic feedback point.
1. A method comprising: a) producing an acoustic field using an array of real transducers having known relative positions and orientations; b) tracking an object within the acoustic field; c) using at least one point of focused ultrasound, defining a virtual shape that occupies a virtual volume within the acoustic field, wherein the at least one point of focused ultrasound is modeled as being produced by a virtual transducer; and d) positioning the at least one point of focused ultrasound in a region where the object intersects the virtual shape.
2. The method as in claim 1 , wherein the virtual transducer is below the at least one point of focused ultrasound.
3. The method as in claim 1 , wherein the virtual transducer is in a plane with the array of real transducers.
4. The method as in claim 1 , wherein the virtual transducer enables a lookup table to be pre-computed.
5. The method as in claim 1 , wherein the virtual transducer matches at least one of the array of real transducers.
6. The method as in claim 1 , wherein tracking an object occurs in real time, and further comprising repositioning the at least one point of focused ultrasound in response to a movement in position of the object.
7. The method of claim 6 , wherein the object is a human hand.
8. The method of claim 1 , wherein an acoustic field comprises ultrasonic frequencies.
9. The method of claim 1 , further comprising a modulator to modulate acoustic waves within the acoustic field at a frequency between 0.1 Hz to 500 Hz.
10. The method of claim 1 , wherein the array of transducers is substantially air coupled.
11. The method of claim 1 , wherein the array of transducers is substantially water coupled.
12. The method of claim 1 , wherein the array of transducers amplitudes are scaled such that a highest amplitude transducer operates at substantially full power.
13. A system comprising: an acoustic field in air produced using a plurality of ultrasonic transducers having known relative positions and orientations to each other, wherein at least one of the plurality of ultrasonic transducers is a virtual transducer; a tracker of an object within the acoustic field; a virtual shape defined using at least one point of focused ultrasound produced from at least two of the plurality of ultrasonic transducers that occupies a virtual volume within the acoustic field, wherein the virtual shape is 3-dimensional; and one of the at least one point of focused ultrasound positioned in a region where the object intersects the virtual shape.
14. The method as in claim 13 , wherein the virtual transducer is below the virtual shape.
15. The method as in claim 13 , wherein the virtual transducer is in a plane with the plurality of ultrasonic transducer.
16. The method as in claim 13 , wherein the virtual transducer enables a lookup table to be pre-computed.
17. The system of claim 13 , wherein one of the at least one point of focused ultrasound is positioned on an edge of the virtual shape.
18. The system of claim 13 , wherein one of the at least one point of focused ultrasound is positioned within the virtual shape.
19. The system of claim 13 , further comprising one of the at least one point of focused ultrasound repositioned in response to a movement of the object.
20. The system of claim 16 , wherein the object is a human hand.
21. The system of claim 13 , further comprising acoustic waves within the acoustic field modulated at a frequency between 0.1 Hz to 500 Hz.
22. The system of claim 13 , further comprising acoustic waves within the acoustic field modulated at a frequency between 0 Hz and half of a carrier frequency of the acoustic waves.
23. A system comprising: an acoustic field in air produced using a plurality of ultrasonic transducers having known relative positions and orientations to each other, wherein at least one of the plurality of ultrasonic transducers is a virtual transducer; a tracker of an object within the acoustic field; a virtual shape defined using at least two points of focused ultrasound produced from at least two of the plurality of ultrasonic transducers that occupies a virtual volume within the acoustic field; wherein two of the at least two points of focused ultrasound are positioned in a region where the object intersects the virtual shape.
24. The method as in claim 23 , wherein the virtual transducer is below the virtual shape.
25. The method as in claim 23 , wherein the virtual transducer is in a plane with the plurality of ultrasonic transducer.
26. The method as in claim 23 , wherein the virtual transducer enables a lookup table to be pre-computed.
27. The system of claim 23 , wherein two of the at least two points of focused ultrasound are positioned on an edge of the virtual shape.
28. The system of claim 23 , wherein two of the at least two points of focused ultrasound are positioned within the virtual shape.
29. The system of claim 23 , further comprising two of the at least two points of focused ultrasound repositioned in response to movement of the object.
30. The system of claim 23 , wherein the object is a human hand.
31. The system of claim 23 , further comprising acoustic waves within the acoustic field modulated at a frequency between 0.1 Hz to 500 Hz.
32. The system of claim 23 , further comprising acoustic waves within the acoustic field modulated at a frequency between 0 Hz and half of a carrier frequency of the acoustic waves.
33. The system of claim 23 , wherein the virtual shape is 3-dimensional.