Method and apparatus for producing an acoustic field

• Main Authors: SRIRAM SUBRAMANIAN, BENJAMIN JOHN OLIVER LONG, THOMAS ANDREW CARTER
• Format: Patent
• Language: English
• Published: 12.11.2014
• Subjects: ACOUSTICS; ACOUSTICS NOT OTHERWISE PROVIDED FOR; CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; MUSICAL INSTRUMENTS; PHYSICS; SOUND-PRODUCING DEVICES

A method of producing an acoustic field from an array of transducers 68 comprises: defining a plurality of control points, such as 80, 82, with a known spatial relationship relative to the array of transducers; assigning an amplitude to each control point; computing a matrix containing elements which represent, for each control point, the effect that producing a modelled acoustic field having the assigned amplitude with a particular phase at the control point has on the consequential amplitude and phase of the field at the other control points; determining eigenvectors of the matrix, each eigenvector representing a set of phases and relative amplitudes of the modelled acoustic field at the control points; and selecting one of the sets and operating the transducer array to cause one or more transducers to output an acoustic wave each having an initial amplitude and phase such that the phases and amplitudes of the resultant acoustic field at the control points correspond to those of the selected set. The acoustic waves may be ultrasound waves, and may provide haptic feedback, such as producing tactile sensations of virtual objects 78 or projecting Braille onto a users hand, or may be used to levitate small objects.