Nec Corporation

Nec C Orporation

Nozomi Toki

Yasuhiro Sasaki

Yasuharu Onishi

Yukio Yokoyama

Masatake Takahashi

Ukyo Mori

Yukio Murata

Jun Kuroda

Yasuharu Oonishi

A piezoelectric acoustic device comprises: at least two piezoelectric actuators; a support body that supports the at least two piezoelectric actuators; and a signal input unit that drives the at least two piezoelectric actuators at respective arbitrary times. At least one pair of piezoelectric actuators among the at least two piezoelectric actuators is arranged in such a manner that their sound radiation surfaces face each other with a predetermined gap.

Piezoelectric acoustic device and electronic apparatus

Piezoelectric actuator () includes a piezoelectric element () that performs expansion/contraction movement in accordance with the state of an electrical field, a base () with the piezoelectric element () adhered to one surface thereof, and a support member () for supporting the piezoelectric element () and the base (), the piezoelectric element () and base () vibrating up and down in accordance with the expansion/contraction movement of the piezoelectric element (). The base () is connected to the support member () by way of a vibration film () having less rigidity than the base (). In addition, the piezoelectric element () and support member () have different outline shapes.

Piezoelectric actuator and electronic apparatus

An electronic device includes a microphone, a microphone holder holding the microphone therein, and a case encasing the microphone holder therein. The microphone holder has a first portion at which the microphone holder makes contact with a first inner surface of the case, and a second portion at which the microphone holder makes contact with one of a part of the electronic device and a second inner surface of the case facing the first inner surface, the microphone holder being sandwiched between the first inner surface and the part. At least one of the first and second portions of the microphone holder is disposed more outwardly than an outer edge of the microphone in a plane which is in parallel with the first inner surface.

Electronic device and microphone holder therefor

A piezoelectric acoustic elementof the present invention comprising a hollow casinghaving a opening, a piezoelectric elementthat is disposed in said casingand bends when a voltage is applied thereto, and diaphragmprovided at the openingof said casing; wherein said piezoelectric elementand said diaphragmare joined through a vibration transmitting member

Piezoelectric acoustic element, acoustic device, and portable terminal device

A piezo-electric actuator comprising: piezo-electric elementhaving piezo-electric bodywhich is provided with at least two opposing surfaces, wherein the surfaces perform an expanding and contracting motion in accordance with the state of an electric field; a constraint memberfor constraining piezo-electric elementon at least one of the two surfaces, a supporting member disposed around constraint member, and a plurality of beam memberseach having both ends fixed to constraint memberand supporting member, respectively, wherein each beam member has a neutral axis for bending in a direction substantially parallel with the constrained surface, wherein the constraint member vibrates by vibration which is generated by the constraining effect between the constraint member and the piezo-electric element, and is amplified by the beam members.

Piezoelectric actuator

This invention has been made to provide a speaker system capable of miniaturization and presenting a good sound quality. A speaker is mounted on a printed circuit board arranged inside a telephone body enclosure . Acoustic waves of positive phase produced by vibration of a diaphragm of the speaker are output through front acoustic apertures and a front air chamber to the exterior from an enclosure acoustic aperture . On the other hand, the acoustic waves of opposite phase enter a rear air chamber through rear acoustic apertures , reach an enclosure internal space through an opposite-phase opening provided by cutting away a part of a rear sealing member , and transmit to a card slot , then being output to the exterior. The opposite-phase opening as an opening allows the acoustic waves to be output in a direction remotest from the card slot , so that the acoustic waves of opposite phase are output to the extension through the remotest path in the enclosure of the speaker resulting in reducing interference of the acoustic waves of positive phase and negative phase. This enables realization of a speaker system of small size but of a good sound quality.

Speaker system

A foldable handy phone of the present invention includes a receiver case and a transmitter case hinged to each other. A piezoelectric device or similar sounding means is accommodated in the receiver case. A through hole is formed in the surface of the receiver case that faces the transmitter case when the handy phone is folded up. The through hole is communicated to a portion accommodating the sounding means. A groove is formed in the above surface of the receiver case and extends from the open end of the through hole to the end of the receiver case opposite to the end hinged to the transmitter case. When the sounding means produces an alert tone in the folded position of the handy phone, the alert tone is radiated to the outside via the groove.

Foldable handy phone

Disclosed is a piezoelectric diaphragm with a transparent piezoelectric member and a transparent electrode. Also disclosed is a portable electronic device that has a display means to display an image and a piezoelectric speaker having a transparent piezoelectric member and a transparent electrode. In this portable electronic device, the piezoelectric speaker is disposed in front of the display means.

Piezoelectric diaphragm and piezoelectric speaker

Apparatus for detecting the opening and closing angle which is easy to switch, is reliable, is capable of positively preventing howling from occurring, can be reduced in size and weight, and uses no special components. The apparatus comprises a first and second hinge portions belonging to a first and second housings, respectively, for pivotal linking said first housing to said second housing. The first hinge portion has on the lateral side a curved surface in a rotational direction of said first housing and comprises a given number of parallel electrodes extending in a rotational direction of said first housing on said convex curved surface. The curved surface portion is disposed in the second housing; the second housing includes therein terminals in pressure contact with said electrodes or the curved surface; the terminals are in contact or non-contact with corresponding electrodes at different predetermined angles depending on the rotation of the first housing.

Opening and closing angle detecting apparatus and foldable device

A D/A converter realizes an output analog signal with less ripple within a wide range and includes (a) a bit recognizer for recognizing at least one bit of a digital input signal to thereby produce a pulse width signal and a control signal; (b) a PWM signal generator for generating a PWM signal with a variable pulse width according to a value of the input signal by modulating the input signal according to a PWM process; and (c) an output circuit for outputting an output pulse voltage according to the value of the input signal. The pulse width of the PWM signal is controlled by the pulse width signal, and the output pulse voltage is controlled by the control signal. The pulse width of the PWM signal and the output pulse voltage are controlled in such a way that an area of a pulse of the PWM signal is equal to an area of every other pulse. Each pulse of the PWM signal may be divided into blocks having different values designed for forming a specific expansion characteristic.

D/A conversion method and a D/A converter using pulse width modulation

A transmitter structure which is resistance to wind noise and the like and allows a reduction in size is disclosed. A sound hole is formed in a case at an offset position with respect to a microphone, and a slit extending from the sound hole to the microphone is filled with an acoustic resistance cloth.

Transmitter structure for limiting the effects of wind noise on a

Disclosed is a PWM driver in which, when no signal is input, a PWM pulse wave is not output so as to thereby reduce a power to be consumed and a high output level can be obtained even by the use of a single-polarity power source. Also, provided is a PWM driver capable of changing an output amplitude by a simple circuit. For this purpose, a PWM driving apparatus for supplying a power proportional to an input signal to a load by outputting a PWM pulse wave whose duty cycle is changed in proportion to the input signal, comprises: a PWM modulator for outputting a first PWM pulse having a pulse width proportional to an absolute value of the input signal in a predetermined cycle; an inverting amplifier for outputting a second PWM pulse having a polarity opposite to the polarity of the first PWM pulse; switch means for outputting the first PWM pulse or the second PWM pulse in response to the polarity of the input signal; and an amplifier for outputting the PWM pulse wave in response to an output pulse of the switch means.

PWM driver

Insulating flexible sheets and electroconductive flexible sheets having electroconductive patterns are stacked alternately into a multi-layer structure to form a laminated body. The inclining directions of the obliquely formed electroconductive patterns are varied alternately from layer to layer, and the patterns of different layers are electrically connected by electroconductive connecting parts formed on the insulating sheets. A pattern of a single line wound in the same direction is formed by rounding the laminated body so as to connect the patterns to each other and thereby form a cylindrical multi-layer coil. Further, by opening the connecting part to make it a tapping part and reducing the number of turns of the multi-layer coil, the inductance of the coil can be set as desired. Alternatively, the electroconductive patterns are formed with the same inclination and the connecting part on each insulating flexible sheet is opened to make it a tapping part, so that each layer constitutes an independent single-layer coil. This plurality of single-layer coils are freely connected whether in series or in parallel.

Method of making multi-layer coil using electroconductive flexible sheets

The piezoelectric-acoustic transducer of the present invention has a hollow case provided with a sound hole. A piezoelectric actuator is disposed inside this case that has one end fixed to the case and that bends in the direction of the thickness of the case when voltage is applied. A diaphragm is secured to one portion of the piezoelectric actuator and is positioned at a distance from the piezoelectric acturator in the direction of the thickness of the case.

Piezoelectric acoustic transducer

Insulating flexible sheets and electroconductive flexible sheets having electroconductive patterns are stacked alternately into a multi-layer structure to form a laminated body. The inclining directions of the obliquely formed electroconductive patterns are varied alternately from layer to layer, and the patterns of different layers are electrically connected by electro-conductive connecting parts formed on the insulating sheets. A pattern of a single line wound in the same direction is formed by rounding the laminated body so as to connect the patterns to each other and thereby form a cylindrical multi-layer coil. Further, by opening the connecting part to make it a tapping part and reducing the number of turns of the multi-layer coil, the inductance of the coil can be set as desired. Alternatively the electroconductive patterns are formed with the same inclination and the connecting part on each insulating flexible sheet is opened to make it a tapping part, so that each layer constitutes an independent single-layer coil. This plurality of single-layer coils are freely connected whether in series or in parallel.

Growing community of inventors

Saitama, Japan

Nozomi Toki