Parametric audio system
First Claim
1. A parametric audio generator comprising:
- (a) an ultrasonic signal source providing a carrier;
(b) a source of audio signals;
(c) means for modulating the carrier with the audio signals, the frequency of the carrier being sufficiently high that all of the components of the modulated carrier have frequency above the range in which the human auditory system responds;
(d) an ultrasonic transducer for radiating ultrasonic signals; and
(e) means for applying the modulated carrier to the transducer.
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Accused Products
Abstract
Ultrasonic signals are used to transmit sounds from a modulated ultrasonic generator to other locations from which the sounds appear to emanate. In particular, an ultrasonic carrier is modulated with an audio signal and demodulated on passage through the atmosphere. The carrier frequencies are substantially higher than those of prior systems, e.g., at least 60 kHz, and the modulation products thus have frequencies which are well above the audible range of humans; as a result, these signals are likely harmless to individuals who are within the ultrasonic fields of the system. The signals may be steered to moving locations, and various measures are taken to minimize distortion and maximize efficiency.
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Citations
47 Claims
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1. A parametric audio generator comprising:
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(a) an ultrasonic signal source providing a carrier;
(b) a source of audio signals;
(c) means for modulating the carrier with the audio signals, the frequency of the carrier being sufficiently high that all of the components of the modulated carrier have frequency above the range in which the human auditory system responds;
(d) an ultrasonic transducer for radiating ultrasonic signals; and
(e) means for applying the modulated carrier to the transducer. - View Dependent Claims (2, 45)
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3. A parametric audio generator comprising:
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(a) an ultrasonic signal source providing an ultrasonic carrier;
(b) first and second ultrasonic transducers, said first transducer having a first acoustical-mechanical resonance and said second transducer having a second acoustical-mechanical resonance at a frequency higher than that of said first transducer;
(c) a source of audio signals;
(d) means for modulating said carrier with the audio signals, whereby the frequency spectrum of the modulated carrier includes both of said transducer resonances; and
(e) means for driving said transducer with the modulated carrier. - View Dependent Claims (4, 5, 6)
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7. A parametric audio system comprising:
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(a) a parametric audio generator transmitting an audio-modulated ultrasonic beam into an enclosed atmosphere; and
(b) aan environmental-control apparatus for controlling at least one of temperature and moisture content of the atmosphere in the path of said beam, thereby to increase the efficiency of demodulation of the audio signal.
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8. A parametric audio system comprising:
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(a) a plurality of parametric audio generators transmitting steerable audio-modulated ultrasonic beams; and
(b) means for steering said beams to provide an atmospheric volume in which the beams intersect, the combined intensity of the beams in said volume providing a demodulated audio signal having a substantially greater level than the level provided by demodulation of a single one of said beams.
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9. A parametric audio generator comprising:
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(a) an ultrasonic carrier generator;
(b) a modulator for modulating the output of the carrier generator with an audio signal;
(c) a transducer for receiving the modulated output of the carrier generator and in response thereto, transmitting a modulated acoustical beam of sufficient intensity to provide atmospheric demodulation the audio signals contained therein;
(d) a source of audio signals;
(e) a preprocessor for conditioning the output of the source to compensate for cross-modulation of audio components in the acoustical beam; and
(f) means for combining output of said audio signal source with the output of said preprocessor and applying the resulting combined audio signal to said modulator.
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10. A parametric audio generator comprising:
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(a) a carrier generator providing an electrical carrier comprising an ultrasonic frequency;
(b) a modulator for modulating the carrier with an audio signal;
(c) a transducer for receiving the modulated carrier and, in response thereto, transmitting a modulated acoustical beam;
(d) a source of input audio signals;
(e) means for applying the input audio signals to said modulator; and
(f) a signal control unit comprising;
(1) a level sensor sensing the audio signal level from said audio source; and
(2) means for controlling the intensity of the carrier in response to the sensed audio signal level.
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11. A parametric audio generator comprising:
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(a) a carrier generator providing an electrical carrier and an ultrasonic frequency and having an amplitude sin(ω
ct);
(b) a modulator for modulating the carrier with an input audio signal (1+∫
∫
g(t)dt);
(c) a transducer for receiving the modulated carrier and, in response thereto, transmitting a modulated acoustical beam;
(d) a source of input audio signals;
(e) an ultrasonic transducer for radiating ultrasonic signals;
(f) a level sensor for providing a level signal, L(t), corresponding to the level of the input audio signals; and
(f) control means responsive to the input audio signals and the level signal for modulating the electrical carrier to provide a modulated signal, p′
(t), of the form
p′
(t)=P1(L(t)+m∫
∫
g(t)dt2)1/2 sin (ω
ct),where m is the modulation depth. - View Dependent Claims (12, 13, 14, 15)
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16. A display system comprising:
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(a) a light-reflecting surface;
(b) a projector for projecting a moving optical image onto said reflecting surface;
(c) a steerable parametric audio generator for transmitting an audio-modulated ultrasonic beam; and
(d) means for steering said audio generator to transmit the ultrasonic beam onto said screen at the location of said optical image, whereby the audio signals demodulated from the ultrasonic beam emanates from the location of the optical image. - View Dependent Claims (17, 18)
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19. A parametric audio generator comprising:
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(a) an ultrasonic signal source providing a carrier;
(b) a source of audio signals;
(c) means for modulating the carrier with the audio signals;
(d) an ultrasonic transducer for radiating ultrasonic signals;
(e) means for applying the modulated carrier to the transducer; and
(f) means for compensating for distortion arising from atmospheric propagation and absorption of the radiated ultrasonic signals. - View Dependent Claims (20, 21, 22)
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23. A parametric audio generator comprising:
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(a) an ultrasonic signal source providing a carrier;
(b) a source of audio signals;
(c) means for modulating the carrier with the audio signals;
(d) an ultrasonic transducer for radiating ultrasonic signals at an output level;
(e) means for applying the modulated carrier to the transducer; and
(f) means for controlling the output of the transducer to avoid subjecting listeners to unsafe output levels. - View Dependent Claims (24)
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25. A method of selectively transmitting audio signals to a selected location, the method comprising the steps of:
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(a) modulating an ultrasonic carrier with at least one audio signal, the frequency of the carrier being sufficiently high that all of the components of the modulated carrier have frequencies above the range in which the human auditory system responds; and
(b) directing a beam containing the modulated carrier toward the location, whereby the audio signal appears to emanate therefrom or is confined thereto. - View Dependent Claims (26, 27, 28, 29, 30, 46, 47)
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31. A method of selectively transmitting audio signals to a selected location, the method comprising the steps of:
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(a) modulating an ultrasonic carrier with at least one audio signal;
(b) directing a beam comparing the modulated carrier toward the location, whereby the audio signal appears to emanate therefrom or is confined thereto; and
(c) controlling at least one atmospheric condition proximate to the location to increase demodulation efficiency. - View Dependent Claims (32, 33)
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34. A method of selectively transmitting audio signals to a selected location, the method comprising the steps of:
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(a) modulating an ultrasonic carrier with at least one audio signal;
(b) directing a beam comparing the modulated carrier toward the location, whereby the audio signal appears to emanate therefrom or is confined thereto;
(c) providing a loudspeaker; and
(d) causing the loudspeaker to reproduce low-frequency components of the audio signal. - View Dependent Claims (35, 36, 37)
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38. A method of transmitting audio signals, the method comprising the steps of:
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(a) modulating an ultrasonic carrier signal with audio signals;
(b) radiating the modulated carrier as ultrasonic signals at an output level; and
(c) compensating for distortion arising from atmospheric propagation of the radiated ultrasonic signals. - View Dependent Claims (39, 40)
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41. A method of transmitting audio signals, the method comprising the steps of:
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(a) modulating an ultrasonic carrier signal with audio signals;
(b) radiating the modulated carrier as ultrasonic signals at an output level; and
(c) controlling ultrasonic signals to as to avoid subjecting listeners to unsafe output levels. - View Dependent Claims (42)
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43. A method of selectively transmitting audio signals to an acoustically isolated region, the method comprising the steps of:
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(a) modulating each of a plurality of ultrasonic carriers with at least one audio signal, the frequency of the carriers being sufficiently high that all of the components of the modulated carrier have frequencies above the range in which the human auditory system responds; and
(b) directing the modulated carriers so as to intersect in a selected region, the carriers having a combined intensity within the selected region such as to provide a demodulated audio signal having a substantially greater level than the audio level provided by demodulation of a single one of the modulated carriers, whereby the audio signal emanates from the selected region. - View Dependent Claims (44)
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Specification