# US 8,541,852 B2 · Acoustic sensor

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,541,852 B2
- Document ID: US8541852B2
- Status: Granted
- Kind: B2
- Application number: 13/106,288
- Filed: 2011-05-12
- Published: 2011-11-17
- Granted: 2013-09-24
- Earliest claimed: 2010-05-13
- Assignees: OMRON Corporation
- Applicants: Takashi Kasai
- Inventors: Takashi Kasai
- Web page: https://patentgrep.com/patent/US8541852B2

## CPC

- G01H 11/06: by electric means
- H04R 19/005: {using semiconductor materials}
- H04R 19/04: Microphones (H04R19/01 takes precedence)
- H04R 31/006: {Interconnection of transducer parts (of diaphragm and outer suspension by moulding H04R31/003)}
- G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## 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.

## Claims

### Claim 1

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.

### Claim 2 (depends on 1)

The acoustic sensor according to claim 1,
wherein three or more types of projections having different cross-sectional areas are arranged; and
wherein the projections are arranged so that the cross-sectional area sequentially becomes smaller toward an outer peripheral side from a center of at least one of the back plate and the vibration electrode film.

### Claim 3 (depends on 1)

The acoustic sensor according to claim 1,
wherein a projection having a relatively small cross-sectional area is arranged in an outer peripheral area of at least one of the back plate and the vibration electrode film, and
wherein a projection having a relatively large cross-sectional area is arranged in an internal area of at least one of the back plate and the vibration electrode film.

### Claim 4 (depends on 3)

The acoustic sensor according to claim 3, wherein a width of the outer peripheral area where the projection having a relatively small cross-sectional area is arranged is smaller than or equal to ¼ of a width of the back plate or the vibration electrode film.

### Claim 5 (depends on 1)

The acoustic sensor according to claim 1,
wherein the semiconductor substrate is formed with a hollow portion from an upper surface to a lower side,
wherein the vibration electrode film is arranged on the upper surface of the semiconductor substrate,
wherein the back plate is fixed on the upper surface of the semiconductor substrate so as to cover the vibration electrode film, and
wherein a plurality of acoustic holes are opened in the back plate.

### Claim 6 (depends on 1)

The acoustic sensor according to claim 1,
wherein a plurality of projections are arranged in a region facing an upper surface of the semiconductor substrate of a lower surface of the vibration electrode film, and
wherein the cross-sectional area of a projection arranged at an outer peripheral part of the region is smaller than the cross-sectional area of a projection arranged at an inner peripheral part of the region.

### Claim 7 (depends on 1)

The acoustic sensor according to claim 1, wherein the back plate is fixed on an upper surface of the semiconductor substrate, and the vibration electrode film is arranged on an upper side of the back plate.