Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Kazumoto Doi

Yoshiyuki Miyashita

Tadao Imai

Hiroaki Iwaseki

Hiroshi Ogura

Futoshi Takeshi

A microphone has: a printed circuit board provided with a first sound hole; a microphone element mounted on a first surface of the printed circuit board so as to cover the first sound hole; a microphone casing provided with a second sound hole opposite to the first sound hole, and housing the printed circuit board so that the second sound hole; and a bush provided with a third sound hole, and having a first contact surface and a second contact surface. The third sound hole is disposed between the first and second sound holes to be communicated with the holes. The first contact surface is in contact with a second surface of the printed circuit board at a first end of the third sound hole. The second contact surface is in contact with an inner surface of the microphone casing at a second end of the third sound hole.

Microphone

A microphone structure has a diaphragm; a frame of which an inside is processed in a shape of a semispherical surface, a parabolic surface, or a conical surface; an acoustic transducer that converts sound pressure into an electric signal; and a wire that transmits the electric signal from the acoustic transducer to outside. A sound pressure input surface of the acoustic transducer is disposed on a bottom surface portion of the semispherical surface, the parabolic surface, or the conical surface inside the frame. The diaphragm and the frame, and the frame and the wire include waterproof mechanisms preventing ingress of water.

In the present invention, a semiconductor substrate wherein a plurality of MEMS microphones is formed is disposed opposed to a discharge electrode in a state of being stuck on a sheet. Electretization of a dielectric film provided in the MEMS microphone is performed by irradiating the dielectric film between a fixed electrode and a vibration film provided in the MEMS microphone with ions resulting from a corona discharge of the discharge electrode in a state that a predetermined potential difference is applied to the fixed electrode and the vibration film and fixing charges based on the ions to the dielectric film. The electretization is successively performed to each MEMS microphone on the semiconductor substrate by relatively moving the semiconductor substrate and the discharge electrode. Therefore, electretization of the dielectric film in the MEMS microphone chip is realized using a low-cost and simple fabricating equipment and productivity can be enhanced.

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Kanagawa, Japan

Kazumoto Doi