Method and device for driving a directional speaker
First Claim
1. A directional speaker that vibrates a diaphragm to send sound waves, comprising:
- reproducing signal generation means for outputting a reproducing audible signal;
ultrasonic signal generation means for outputting a carrier wave signal at a frequency in an ultrasonic band;
phase modulation means for phase modulating the carrier wave signal with the reproducing audible signal to output a modulated carrier wave signal; and
diaphragm driving means for vibrating said diaphragm based on a compression cycle of the modulated carrier wave signal.
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Accused Products
Abstract
A directional speaker that vibrates a diaphragm to send sound waves includes reproducing signal generation means 10 for outputting a reproducing audible signal; ultrasonic signal generation means 20 for outputting a carrier wave signal at a frequency in an ultrasonic band; phase modulation means 30 for phase modulating the carrier wave signal with the reproducing audible signal to output a modulated carrier wave signal; and diaphragm driving means 50 for vibrating the diaphragm based on a compression cycle of the modulated carrier wave signal. The configuration, in which the ultrasonic carrier wave is modulated with an audio signal, can generate a small, narrow-directional audible sound field without using a parametric effect. At the same time, the ultrasonic carrier wave is modulated in such a way that the sound pressure distribution of a target audio signal (reproducing audible signal) can be obtained for output and, therefore, the sound quality of a sound signal output from the directional speaker is improved.
55 Citations
40 Claims
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1. A directional speaker that vibrates a diaphragm to send sound waves, comprising:
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reproducing signal generation means for outputting a reproducing audible signal;
ultrasonic signal generation means for outputting a carrier wave signal at a frequency in an ultrasonic band;
phase modulation means for phase modulating the carrier wave signal with the reproducing audible signal to output a modulated carrier wave signal; and
diaphragm driving means for vibrating said diaphragm based on a compression cycle of the modulated carrier wave signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A directional speaker that vibrates a diaphragm to send sound waves, comprising:
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reproducing signal generation means for outputting a reproducing audible signal;
ultrasonic signal generation means for outputting a carrier wave signal at a frequency in an ultrasonic band;
angle modulation means for modulating the carrier wave signal with the reproducing audible signal to output a modulated carrier wave signal; and
diaphragm driving means for vibrating said diaphragm based on a compression cycle of the modulated carrier wave signal, wherein the carrier wave signal is a rectangular wave at a frequency of 40 kHz to 100 kHz and a duty ratio of the rectangular wave is a value selected from a range 20% to 80%.
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19. A directional speaker that vibrates a diaphragm to send sound waves, comprising:
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reproducing signal generation means for outputting a reproducing audible signal;
ultrasonic signal generation means for outputting a carrier wave signal at a frequency in an ultrasonic band;
angle modulation means for modulating the carrier wave signal with the reproducing audible signal to output a modulated carrier wave signal;
diaphragm driving means for vibrating said diaphragm based on a compression cycle of the modulated carrier wave signal; and
a filter, provided between said angle modulation means and said diaphragm driving means, for passing a predetermined frequency component of the modulated carrier wave signal, wherein the passing area of said filter is a frequency area that does not include a resonance point in sound pressure characteristics for the frequency of said diaphragm driving means.
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20. A directional speaker that vibrates a diaphragm to send sound waves, comprising:
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reproducing signal generation means for outputting a reproducing audible signal;
ultrasonic signal generation means for outputting a carrier wave signal at a frequency in an ultrasonic band;
angle modulation means for modulating the carrier wave signal with the reproducing audible signal to output a modulated carrier wave signal;
diaphragm driving means for vibrating said diaphragm based on a compression cycle of the modulated carrier wave signal; and
amplitude change means provided between said angle modulation means and said diaphragm driving means wherein, based on amplitude characteristics for the frequency of said amplitude change means, sound pressure characteristics for the frequency of said diaphragm driving means are corrected to predetermined sound pressure characteristics.
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21. A method for driving a directional speaker that vibrates a diaphragm to send sound waves, comprising the steps of:
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phase modulating a carrier wave signal at a frequency in an ultrasonic band with a reproducing audible signal output from reproducing signal generation means, said carrier wave signal being output by ultrasonic signal generation means, said phase modulation being carried out by phase modulation means; and
vibrating said diaphragm based on a compression cycle of a modulated carrier wave signal obtained by said phase modulation. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method for driving a directional speaker that vibrates a diaphragm to send sound waves, comprising the steps of:
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modulating a carrier wave signal at a frequency in an ultrasonic band with a reproducing audible signal output from reproducing signal generation means, said carrier wave signal being output by ultrasonic signal generation means, said modulation being carried out by angle modulation means; and
vibrating said diaphragm based on a compression cycle of a modulated carrier wave signal obtained by said modulation wherein the carrier wave signal is a rectangular wave at a frequency of 40 kHz to 100 kHz and a duty ratio of the rectangular wave is a value selected from a range 20% to 80%.
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39. A method for driving a directional speaker that vibrates a diaphragm to send sound waves, comprising the steps of:
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modulating a carrier wave signal at a frequency in an ultrasonic band with a reproducing audible signal output from reproducing signal generation means, said carrier wave signal being output by ultrasonic signal generation means, said modulation being carried out by angle modulation means; and
vibrating said diaphragm based on a compression cycle of a modulated carrier wave signal obtained by said modulation wherein a predetermined frequency component that is included in the modulated carrier wave signal output by said angle modulation means and that does not include a resonance point in sound pressure characteristics for the frequency of diaphragm driving means is passed and the diaphragm is vibrated by the modulated carrier wave signal of the predetermined frequency component.
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40. A method for driving a directional speaker that vibrates a diaphragm to send sound waves, comprising the steps of:
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modulating a carrier wave signal at a frequency in an ultrasonic band with a reproducing audible signal output from reproducing signal generation means, said carrier wave signal being output by ultrasonic signal generation means, said modulation being carried out by angle modulation means; and
vibrating said diaphragm based on a compression cycle of a modulated carrier wave signal obtained by said modulation wherein an amplitude of the modulated carrier wave signal output by said angle modulation means is changed and, based on frequency characteristics of the amplitude, sound pressure characteristics for the frequency of diaphragm driving means, which drives said diaphragm, are corrected to predetermined sound pressure characteristics.
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Specification