Superdirectional Acoustic System and Projector

• US 20070274541A1
• Filed: 06/20/2005
• Published: 11/29/2007
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Matsuzawa, Kinya, Uetake, Akihito
• Granted Patent: US 8,130,973 B2
• Time in Patent Office: Days
• US Class Current: 381/150
• CPC Class Codes: G10K 15/02 Synthesis of acoustic waves synthesis of speech G10L13/00
• CPC Class Codes: H04R 1/323 for loudspeakers H04R1/34 and H04R1/40 take precedence
• CPC Class Codes: H04R 2217/03 Parametric transducers where sound is generated or captured by the acoustic demodulation of amplitude modulated ultrasonic waves
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F

Abstract

A superdirectional acoustic system for reproducing a sound signal supplied from a real sound source by using a superdirectional speaker and producing a virtual sound source in a vicinity of a sound wave reflection surface. The system includes an ultrasonic speaker, which includes an ultrasonic transducer for oscillating a sound wave in an ultrasonic frequency band, for reproducing an audio signal in a relatively medium to high frequency sound range, which is included in the sound signal supplied from the real sound source; and a low frequency sound reproducing speaker for reproducing an audio signal in a relatively low frequency sound range, which is included in the sound signal supplied from the real sound source. Sound in the medium-high frequency range is reproduced in a manner such that the sound is produced from a virtual sound source which is formed in the vicinity of the sound signal reflection surface such as a screen.

Claims

1. A superdirectional acoustic system for reproducing a sound signal supplied from a real sound source by using a superdirectional speaker and producing a virtual sound source in a vicinity of a sound wave reflection surface, the system comprising:

an ultrasonic speaker, which includes an ultrasonic transducer for oscillating a sound wave in an ultrasonic frequency band, for reproducing an audio signal in a relatively medium to high frequency sound range, which is included in the sound signal supplied from the real sound source; and

a low frequency sound reproducing speaker for reproducing an audio signal in a relatively low frequency sound range, which is included in the sound signal supplied from the real sound source.

2. A superdirectional acoustic system comprising:

a sound source for supplying a sound signal;

a signal isolating device for isolating an audio signal in a relatively medium to high frequency sound range and an audio signal in a relatively low frequency sound range from the sound signal;

an ultrasonic speaker for reproducing the isolated audio signal in the medium to high frequency sound range; and

a low frequency sound reproducing speaker for reproducing the isolated audio signal in the low frequency sound range.

3. A superdirectional acoustic system as claimed in claim 2, wherein the ultrasonic speaker includes:

a carrier wave supplying device for generating and outputting a carrier wave in an ultrasonic frequency band;

a modulating device for modulating the carrier wave by the isolated audio signal in the medium to high frequency sound range; and

an ultrasonic transducer for oscillating an ultrasonic wave, wherein the ultrasonic transducer, driven by a modulated signal output from the modulating device, converts the modulated signal to a sound wave having a finite amplitude level and emits the sound wave toward a medium.

4. A superdirectional acoustic system as claimed in claim 3, wherein the carrier wave has a frequency which is determined by designating an arrival distance of the sound wave, measured from a sound wave emitting surface of the ultrasonic transducer along an emission axis to an arrival point of the sound wave.

5. A superdirectional acoustic system as claimed in claim 3, wherein the medium is air.

6. A projector comprising:

an ultrasonic speaker for reproducing an audio signal in an audio frequency sound range, which is included in a sound signal supplied from a sound source, wherein the ultrasonic speaker includes an ultrasonic transducer for oscillating a sound wave in an ultrasonic frequency band;

a projector main portion having a projection optical system for projecting an image onto a projection surface; and

a low frequency sound reproducing speaker, wherein;

an audio signal in a relatively medium to high frequency sound range, which is included in the sound signal supplied from the sound source, is reproduced by the ultrasonic speaker; and

an audio signal in a relatively low frequency sound range, which is included in the sound signal supplied from the sound source, is reproduced by the low frequency sound reproducing speaker.

7. A projector comprising:

a sound source for supplying a sound signal;

a signal isolating device for isolating an audio signal in a relatively medium to high frequency sound range and an audio signal in a relatively low frequency sound range from the sound signal;

an ultrasonic speaker for reproducing the isolated audio signal in the medium to high frequency sound range;

a low frequency sound reproducing speaker for reproducing the isolated audio signal in the low frequency sound range; and

a projector main portion having a projection optical system for projecting an image onto a projection surface.

8. A projector as claimed in claim 7, wherein the ultrasonic speaker includes:

a carrier wave supplying device for generating and outputting a carrier wave in an ultrasonic frequency band;

a modulating device for modulating the carrier wave by the isolated audio signal in the medium to high frequency sound range; and

an ultrasonic transducer for oscillating an ultrasonic wave, wherein the ultrasonic transducer, driven by a modulated signal output from the modulating device, converts the modulated signal to a sound wave having a finite amplitude level and emits the sound wave toward a medium.

9. A projector as claimed in claim 8, wherein the carrier wave has a frequency which is determined by designating an arrival distance of the sound wave, measured from a sound wave emitting surface of the ultrasonic transducer along an emission axis to an arrival point of the sound wave.

10. A projector as claimed in claim 8, wherein the medium is air.