Ultrasound based parametric loudspeaker system
AssigneeDaimlerChrysler AG
InventorsGuido Kolano, Klaus Linhard
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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.
Claims27
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.
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.
Dependencies are inferred from the claim text.