Omron Corporation

Akihiro Okugawa

Takashi Kasai

Koji Momotani

An acoustic sensor adapted to convert acoustic vibration to a change in an electrostatic capacitance to detect the acoustic vibration is provided. The acoustic sensor includes a semiconductor substrate, a back plate including a fixed plate arranged to face a surface of the semiconductor substrate, and a fixed electrode film arranged on the fixed plate, and a vibrating electrode film arranged to face the back plate with a space formed therebetween. The vibrating electrode film includes a plate-like vibrating member that vibrates in response to sound pressure. The vibrating electrode film is fixed to the back plate with a fixing unit thereof including one or more fixing portions each including a fixing protruding end that is arranged on a protruding end of a leg portion protruding from an edge of the vibrating member. The vibrating member has an edge portion surrounding at least a part of the fixing protruding end.

Acoustic sensor

A capacitance-type transducer has a back plate having a fixed electrode, a diaphragm that opposes the back plate via an air gap and serves as a movable electrode, and at least first stoppers having a first projection length and second stoppers having a second projection length that project from at least one of a surface of the back plate on the air gap side and a surface of the diaphragm on the air gap side. At least one of the diaphragm and the fixed electrode is divided into at least a first region having a first surface area and a second region having a second surface area, a first sensing portion made up of the diaphragm and the fixed electrode is constituted in the first region, and a second sensing portion made up of the diaphragm and the fixed electrode is constituted in the second region.

Capacitance-type transducer

A capacitive transducer has a back plate including a fixed electrode, a diaphragm facing the back plate with an air gap interposed therebetween, the diaphragm acting as a movable electrode, at least a first stopper of a first protruding length, and a second stopper of a second protruding length. The first and second stoppers protrude from at least either the surface on the back plate near the air gap or the surface on the diaphragm near the air gap. The first stopper is provided at a position corresponding to a first position on the diaphragm. The second the stopper is provided at a position corresponding to a second position on the diaphragm. An amount of displacement of the diaphragm at the first position is greater than an amount of displacement of the diaphragm at the second position. The protruding length of the first stopper is shorter than the protruding length of the second stopper.

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Kyoto, Japan

Akihiro Okugawa