Ultrasound based parametric loudspeaker system
First Claim
1. Process for controlling a parametric loudspeaker system, comprised of one or more transducer elements for ultrasound, which can be driven to produce an AM-signal, which during propagation in a gaseous medium produces an audible signal by self demodulation, one or more amplifiers associated with these transducer elements, and one or more modulators associated therewith, which receive an input signal from a signal source, thereby characterized, that the transducers are driven with an FM-modulated signal (FM-modulation) in the area of the slope of their resonant characteristic lines.
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Abstract
A parametric loudspeaker system is described which is based upon the FM-modulation of an ultrasound carrier. Known systems work with AM-modulation. The FM-modulation produces a good matching to the resonant transducer such as the conventionally employed piezo-ceramic transducers. The resonance slope of the transducers is used for FM/AM-conversion. This FM-resonance principle can advantageously be employed in a multi-path loudspeaker system, in which the transducer works in the optimal resonance range in each of the paths. With the conventional AM-modulation this is not possible. The FM-resonance principle can also be used in resonance-free or resonance-poor transducers, such as for example electrostatic transducers.
10 Citations
27 Claims
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1. Process for controlling a parametric loudspeaker system, comprised of
one or more transducer elements for ultrasound, which can be driven to produce an AM-signal, which during propagation in a gaseous medium produces an audible signal by self demodulation, one or more amplifiers associated with these transducer elements, and one or more modulators associated therewith, which receive an input signal from a signal source, thereby characterized, that the transducers are driven with an FM-modulated signal (FM-modulation) in the area of the slope of their resonant characteristic lines.
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14. Device for controlling a parametric loudspeaker system, comprised of
one or more transducer elements for ultrasound, which can be driven to produce an AM-signal, which during propagation in a gaseous medium produces an audible signal by self demodulation, one or more amplifiers associated with these transducer elements, and one or more modulators associated therewith, which receive an input signal from a signal source, thereby characterized, that means are provided for driving transducers with an FM-modulated signal (FM-modulation) in the area of the slope of their resonant characteristic lines.
Specification