Seiko Epson Corporation

Kinya Matsuzawa

Hirokazu Sekino

Shinichi Miyazaki

Hiroshi Miyazawa

Yoshiki Fukui

Norio Ito

Koichi Saito

Yasushi Soya

Katsunori Yamazaki

Hiroyuki Yoshino

Shoichi Iino

Hideki Kojima

Yoshitaka Iijima

Akihito Uetake

Masatoshi Moteki

Mutsuto Tezuka

A load driving circuit that generates a desired voltage waveform to drive a load includes a target voltage waveform output section that outputs a target voltage waveform to be applied to the load. Power supply sections generate electrical power with voltage values different from each other. Negative feedback control sections between the power supply sections and the load supply electrical power from the corresponding power supply sections to the load and execute negative feedback control of a value of a voltage applied to the load for matching the voltage value and the target voltage waveform. A power supply connection section selects one of the power supply sections based on the value of the voltage applied to the load or the voltage value of the target voltage waveform and connects the selected power supply section to the load and disconnects the rest of the power supply sections from the load.

Load driving circuit and load driving method

A push-pull-type electrostatic-type ultrasonic transducer includes a first electrode having through holes, a second electrode having through holes each of which is paired with the corresponding through hole of the first electrode, and an oscillation film sandwiched between a pair of the first and second electrodes and having a conductive layer to which direct current bias voltage is applied. When a wavelength obtained from a resonance frequency at a mechanical oscillation resonance point of the oscillation film is &#x3bb;, a thickness t of the respective fixed electrodes is (&#x3bb;/4)&#xb7;n or substantially (&#x3bb;/4)&#xb7;n (where &#x3bb;: wavelength of ultrasonic wave, n: positive odd number). AC signals as modulation waves produced by modulating carrier waves in an ultrasonic frequency band by signal waves in an audio frequency band are applied between a pair of the electrodes.

Drive control method of electrostatic-type ultrasonic transducer, electrostatic-type ultrasonic transducer, ultrasonic speaker using electrostatic-type ultrasonic transducer, audio signal reproducing method, superdirectional acoustic system, and display

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.

Superdirectional acoustic system and projector

An electrostatic ultrasonic transducer includes a first electrode that has through-holes, a second electrode that has through-holes, and a vibrating membrane that is disposed such that the through-holes of the first electrode and the through-holes of the second electrode form a pair, interposed between a pair of electrodes composed of the first electrode and the second electrode, and having a conductive layer applied with a direct current bias voltage. The first electrode and the second electrode each have counter electrode portions that are formed in the through-holes to face the vibrating membrane, and a modulated wave, which is obtained by modulating a carrier wave in an ultrasonic frequency band with a signal wave in an audible frequency band, is applied between the pair of electrodes.

Electrostatic ultrasonic transducer and ultrasonic speaker

An ultrasonic transducer includes: a pair of fixed electrodes including a conductive member; a vibrating film having a conductive layer; and a member which holds the pair of fixed electrodes and the vibrating film. The vibrating film is formed of nonconductive bodies and has an electrode layer formed of a conductive material. The electrode layer is applied with a DC bias voltage of a single polarity by a DC bias supply, and is also applied with an AC signal output from a signal source superimposed on the DC bias voltage. The pair of fixed electrodes have a plurality of holes of the same number at positions facing each other via the vibrating film, and an AC signal is applied between the conductive members of the pair of fixed electrodes by the signal source.

Ultrasonic transducer and ultrasonic speaker using the same

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.

Ultrasonic speaker and projector

An ultrasonic speaker or acoustic system includes an electrostatic type ultrasonic transducer of a push-pull system is constructed such that a through hole is arranged in the central portion of a fixing electrode of a circular shape. A sound wave reflecting plate is arranged on the rear face of the ultrasonic transducer and an ultrasonic wave radiated from the rear face of the ultrasonic transducer is reflected by the sound wave reflecting plate and is radiated to the front face of the ultrasonic transducer through the through hole.

Ultrasonic transducer, ultrasonic speaker, acoustic system, and control method of ultrasonic transducer

A Push-Pull-type electrostatic ultrasonic transducer includes a first electrode having a through hole, a second electrode having a through hole making a pair with the through hole of the first electrode, and a vibration film held between a pair of electrodes composed of the first and the second electrodes and having a conductive layer to which a direct-current bias voltage is applied, and holds the pair of electrodes and the vibration film. Assuming that &#x3bb; is the wavelength of the carrier wave having a frequency shifted as a predetermined amount of frequency from the resonance frequency, which is the mechanical resonance frequency of the vibration film, the thickness t of each of the pair of electrodes is set to (&#x3bb;/4)&#xb7;n or roughly (&#x3bb;/4)&#xb7;n (where, &#x3bb; is the wavelength of the ultrasonic wave, n is a positive odd number), and an alternating-current signal, which is a modulated wave obtained by modulating the carrier wave in the ultrasonic frequency band with a signal wave in an audible frequency band, is applied between the pair of electrodes.

Electrostatic ultrasonic transducer drive control method, electrostatic ultrasonic transducer, ultrasonic speaker using the same, audio signal reproduction method, ultra-directional acoustic system, and display device

An ultrasonic transducer includes: a fixed electrode having corrugations on the surface; a vibrating film having an electrode layer and disposed on the surface of the fixed electrode; and a holding member which holds the fixed electrode and the vibrating film. The ultrasonic transducer is driven by applying an AC signal between the electrode layer of the vibrating film and the fixed electrode, and generates a sound pressure of at least 120 dB within a frequency range from 20 kHz to 120 kHz.

The present invention relates to a push-pull type electrostatic ultrasonic transducer, particularly, an electrostatic ultrasonic transducer capable of generating usual sound pressure with lower energy, and thereby, reducing voltage (lowering power); wherein the spacing between the electrodes and vibrating film is set to a specific distance.

Electrostatic ultrasonic transducer, ultrasonic speaker and display device

An electrostatic ultrasonic transducer that includes: a first electrode that is formed with a plurality of holes; a second electrode that is formed with a plurality of holes, and is used in pair with the first electrode; an oscillation film formed with a conductor layer that is sandwiched between the pair of electrodes, and the conductor layer is applied with a direct-current (DC) bias voltage; and a retention member that keeps hold of the pair of electrodes and the oscillation film. In the transducer, an alternating signal is applied between the pair of electrodes, and the pair of electrodes each have a thickness t of about (&#x3bb;/4)&#xb7;n (where &#x3bb; denotes a wavelength of ultrasound, and n denotes a positive odd number).

Electrostatic ultrasonic transducer, ultrasonic speaker, audio signal reproduction method, electrode manufacturing method for use in ultrasonic transducer, ultrasonic transducer manufacturing method, superdirective acoustic system, and display device

A projector having an ultrasonic speaker including an ultrasonic transducer for emitting an ultrasonic wave signal to a screen; a distance measuring device for measuring a distance between the ultrasonic transducer and the screen; and an ultrasonic frequency control device for controlling a frequency of the ultrasonic wave signal based on a measured result of the distance measuring device and a sound pressure of the ultrasonic wave signal emitted by the ultrasonic transducer, so that the ultrasonic wave signal has a predetermined sound pressure at or in a vicinity of the screen. The projector may include a storage device for storing a propagation loss characteristic in air of the ultrasonic wave signal emitted from the ultrasonic transducer. The ultrasonic frequency control device controls the frequency of the ultrasonic wave signal by referring to the propagation loss characteristic of the ultrasonic wave signal stored in the storage device.

Projector and method of controlling ultrasonic speaker in projector

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. Also, sound wave reflection plates are provided to both of the two sound wave output surfaces of the ultrasonic transducer so that the sound waves outputted from each of the two sound wave output surfaces are reflected in the sound wave emitting direction.

An electrostatic type ultrasonic transducer of a push-pull system is constructed such that a through hole is arranged in the central portion of a fixing electrode of a circular shape. A sound wave reflecting plate is arranged on the rear face of the ultrasonic transducer and an ultrasonic wave radiated from the rear face of the ultrasonic transducer is reflected by the sound wave reflecting plate and is radiated to the front face of the ultrasonic transducer through the through hole.

Growing community of inventors

Shiojiri, Japan

Kinya Matsuzawa