Acoustic sensor
AssigneeOMRON Corporation
InventorTakashi Kasai
Life of this patent
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Abstract
A diaphragm for sensing sound pressure faces a back plate including a plate portion and a fixed electrode film to form a capacitance type acoustic sensor. The back plate is opened with acoustic holes for passing vibration, and is arranged with a plurality of stoppers in a projecting manner on a surface facing the diaphragm. The stopper arranged in an outer peripheral area of the back plate has a small diameter, and the stopper arranged in an internal area has a large diameter. Thus, sticking of the diaphragm is prevented, and the diaphragm is less likely to break by impact when the sensor is dropped.
Claims7
An acoustic sensor, comprising:
- a back plate comprising:
- a fixed film arranged on an upper side of a semiconductor substrate;
- and
- a fixed electrode film arranged on the fixed film;
- and
- a vibration electrode film arranged on the upper side of the semiconductor substrate to face the back plate through a void,
- wherein the acoustic sensor converts an acoustic vibration into a change in electrostatic capacitance between the vibration electrode film and the fixed electrode film,
- wherein a plurality of types of projections are arranged on a surface on the void side of at least one of the back plate and the vibration electrode film, and
- wherein a cross-sectional area of the plurality of types of projections is differed according to a projection forming region in at least one of the back plate and the vibration electrode film.
Dependencies are inferred from the claim text.