Parametric loudspeaker with improved phase characteristics
First Claim
Patent Images
1. A parametric loudspeaker system, comprising:
- an electronic modulator, adapted to receive audio signals, wherein the electronic modulator generates a carrier frequency to be modulated with the audio signals to produce a modulated signal;
at least two ultrasonic transducers, coupled to the electronic modulator to reproduce the modulated signal, the at least two ultrasonic transducers each having at least one resonant frequency, wherein the carrier frequency is offset from each at least one resonant frequency in view of the rate of change of phase of each transducer in the vicinity of each at least one resonant frequency in order to increase the phase coherence and combined parametric output of said transducers.
13 Assignments
0 Petitions
Accused Products
Abstract
A parametric loudspeaker which uses multiple piezoelectric bimorph transducers. These multiple piezoelectric bimorphs have a resonant frequency which varies from unit to unit. The phase response at and near the resonant frequency changes at a very high rate with slight changes in frequency. The associated modulator electronics have a primary carrier frequency that is optimized for maximum parametric output. This is achieved by aligning the carrier frequency with the flattest portions of the phase curve for maximum phase coordination among the multiple devices.
-
Citations
34 Claims
-
1. A parametric loudspeaker system, comprising:
-
an electronic modulator, adapted to receive audio signals, wherein the electronic modulator generates a carrier frequency to be modulated with the audio signals to produce a modulated signal;
at least two ultrasonic transducers, coupled to the electronic modulator to reproduce the modulated signal, the at least two ultrasonic transducers each having at least one resonant frequency, wherein the carrier frequency is offset from each at least one resonant frequency in view of the rate of change of phase of each transducer in the vicinity of each at least one resonant frequency in order to increase the phase coherence and combined parametric output of said transducers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
-
-
27. A method for increasing the parametric output of a parametric loudspeaker system, comprising the steps of:
-
(a) providing multiple parametric emitters that output signals in a frequency band;
(b) correlating and controlling the phase relationships to increase phase coherence between each parametric emitter to maximize parametric output, wherein said controlling and correlating includes offsetting a carrier frequency applied to each emitter from a resonant frequency of each emitter in view of a rate of change of phase of each emitter in the vicinity of each resonant frequency; and
(c) emitting ultrasonic energy from the parametric emitters, wherein the correlated phase relationship increases the parametric output.
-
-
28. A method for increasing the parametric output of a parametric loudspeaker system, comprising the steps of:
-
(a) generating a carrier frequency in an electronic modulator;
(b) providing at least two ultrasonic emitters connected to the electronic modulator, wherein the ultrasonic transducers each have a resonant frequency;
(c) offsetting the carrier frequency from each resonant frequency in view of the rate of change of phase of each emitter in the vicinity of said resonant frequency;
(d) modulating the carrier frequency with audio signals received into the electronic modulator, to produce a modulated signal;
(e) reproducing the modulated signal using the offset carrier frequency to increase the combined parametric output of the emitters. - View Dependent Claims (29, 30, 31, 32, 33, 34)
-
Specification