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US 8,009,846 B2Granted
Ultrasonic speaker and projector
AssigneeSeiko Epson Corporation
InventorsHirokazu Sekino, Kinya Matsuzawa, Yoshiki Fukui, Shinichi Miyazaki
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AssigneeSeiko Epson Corporation
InventorsHirokazu Sekino, Kinya Matsuzawa, Yoshiki Fukui, Shinichi Miyazaki
Estimating the term…
An ultrasonic speaker including: a vibration film having a conductive layer; a pair of fixed electrodes provided oppositely to respective surfaces of the vibration film; and an ultrasonic transducer that causes the vibration film to generate sound waves by applying a DC bias voltage to the conductive layer of the vibration film while applying an alternating signal between the pair of fixed electrodes, and outputs the sound waves generated by the vibration film from two sound wave output surfaces via through-holes provided in each of the pair of fixed electrodes. The two sound wave output surfaces of the ultrasonic transducer are disposed in a direction intersecting with a sound wave emitting direction at right angles.
An ultrasonic speaker, comprising:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
Making use of electrical energy: electrostatic transducers, e.g. electret-type
Sound-focusing or directing, e.g. scanning: using reflection, e.g. parabolic reflectors
Electrostatic motors: of the gap-closing type
Piezoelectric transducers; Electrostrictive transducers: using a piezoelectric polymer
Term ended 24 Jul 2025 (estimated)
1. Technical Field
The present invention relates to an ultrasonic speaker and a projector incorporating the ultrasonic speaker, and more particularly, to an ultrasonic speaker capable of utilizing all the sound waves emitted from both sound wave output surfaces of a push-pull electrostatic ultrasonic transducer as a sound source and a projector.
2. Related Art
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements, and wherein:
FIG. 1 is a view showing an example of the configuration of an ultrasonic speaker of the invention;
FIG. 2 is a view showing an example of the configuration of a vibration film;
A best mode for carrying out the invention will now be described with reference to the accompanying drawings.
FIG. 1 is a view showing an example of the configuration of an ultrasonic speaker of the invention. Referring to FIG. 1, an audible frequency signal source 11 generates an audible frequency signal (for example, an audio signal). A carrier signal source 12 generates a carrier signal (carrier wave signal) in an ultrasonic frequency band. A modulation portion 13 modulates a carrier signal in the ultrasonic frequency band generated in the carrier signal source 12 into an audible frequency signal. A pre-amplifier 14 pre-amplifies a modulated signal, and a power amplifier 15 further amplifies the modulated signal. An ultrasonic transducer 30 converts the modulated signal amplified by the power amplifier 15 into a sound wave (ultrasonic wave) and emits the sound wave into air.
Ultrasonic waves emitted from the ultrasonic transducer 30 undergo the parametric effect while propagating into the air, and they are demodulated into audible frequency sound waves by themselves to allow individuals to hear them as audible sounds.