CAPACITIVE ACCELERATION SENSOR

• US 20090007669A1
• Filed: 05/12/2008
• Published: 01/08/2009
• Est. Priority Date: 07/06/2007
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: FUKAURA, Teruya
• Granted Patent: US 8,312,770 B2
• Time in Patent Office: Days
• US Class Current: 73/514.320
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/031 Anodic bondings
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

A capacitive acceleration sensor is provided in which sticking of a mass body, made of silicon, to a first sealing substrate or a second sealing substrate, made of glass, is prevented. The capacitive acceleration sensor, including a first sealing substrate and a second sealing substrate each made of glass, is characterized by containing therebetween: an acceleration detecting portion, made of silicon, including a mass body 4 supported in the air to have predetermined gaps each to the first sealing substrate and the second sealing substrate, a beam 7, connected to the mass body 4 for supporting the mass body 4 in the air, having elasticity to enable the mass body 4 to be displaced, and a fixed electrode 8 provided to face the mass body 4 with a predetermined gap thereto; and a bonding frame 2, made of silicon, provided so as to surround the periphery of the acceleration detecting portion, in which at least one of the first sealing substrate and the second sealing substrate includes, at a position thereof facing the mass body 4, a contact portion 13 with which a part of the mass body 4 comes in contact.

Claims

1. A capacitive acceleration sensor including a first sealing substrate and a second sealing substrate each made of glass, the sensor comprising therebetween:

an acceleration detecting portion, made of silicon, including;

a mass body supported in the air to have predetermined gaps each to the first sealing substrate and to the second sealing substrate,

a beam, connected to the mass body for supporting the mass body in the air, having elasticity to enable the mass body to be displaced, and

a fixed electrode provided to face the mass body with a predetermined gap thereto;

a bonding frame, made of silicon, provided so as to surround the periphery of the acceleration detecting portion; and

at least one of the first sealing substrate and the second sealing substrate including, at a position thereof facing the mass body, a contact portion with which a part of the mass body comes into contact.

2. A capacitive acceleration sensor as recited in claim 1, wherein at least one of the first sealing substrate and the second sealing substrate including the contact is provided with a concavity at a position thereof facing the mass body, in such a way that the peripheral portion of the mass body comes into contact in the contact portion with the substrate.

3. A capacitive acceleration sensor as recited in claim 1, wherein at least one of the first sealing substrate and the second sealing substrate including the contact is provided with a protrusion at a position thereof facing the mass body, in such a way that the center of the mass body comes into contact in the contact portion with the substrate.

4. A capacitive acceleration sensor as recited in any one of claims 1 through 3, wherein a contact range of the contact portion with which the mass body comes into contact is determined, in such a way that at the position where the mass body comes into contact with the contact portion, sticking force by which the mass body is stuck to the contact portion becomes lower than recovery force due to the elasticity of the beam that is intended for taking the mass body away from the contact portion.

5. A capacitive acceleration sensor including a first sealing substrate made of silicon, and a second sealing substrate made of glass, the sensor comprising therebetween:

an acceleration detecting portion, made of silicon, including;

a mass body supported in the air to have predetermined gaps each to the first sealing substrate and to the second sealing substrate,

a beam, connected to the mass body for supporting the mass body in the air, having elasticity to enable the mass body to be displaced, and

a fixed electrode provided to face the mass body with a predetermined gap thereto;

a bonding frame, made of silicon, provided so as to surround the periphery of the acceleration detecting portion; and

the second sealing substrate including, at a position thereof facing the mass body a contact portion with which a part of the mass body comes into contact.

6. A capacitive acceleration sensor as recited in claim 5, wherein the second sealing substrate is provided with a concavity at a position thereof facing the mass body, in such a way that the peripheral portion of the mass body comes into contact in the contact portion with the substrate.

7. A capacitive acceleration sensor as recited in claim 5, wherein the second sealing substrate is provided with a protrusion at a position thereof facing the mass body, in such a way that the center of the mass body comes into contact in the contact portion with the substrate.

8. A capacitive acceleration sensor as recited in any one of claims 5 through 7, wherein a contact range of the contact portion with which the mass body comes into contact is determined, in such a way that at the position where the mass body comes into contact with the contact portion, sticking force by which the mass body is stuck to the contact portion becomes lower than recovery force due to the elasticity of the beam that is intended for taking the mass body away from the contact portion.