Inertial sensor

• US 20050217373A1
• Filed: 03/29/2005
• Published: 10/06/2005
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Fujitsu Limited, Fujitsu Media Devices Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Limited, Fujitsu Media Devices Limited (Fujitsu Limited)
• Inventors: Nagata, Kenji, Ishikawa, Hiroshi, Nakamura, Yoshitaka, Tokunaga, Hiroshi
• Granted Patent: US 7,019,231 B2
• Time in Patent Office: Days
• US Class Current: 73/493
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0842 the mass being of clover leaf shape

Abstract

An inertial sensor includes a sensing portion having a weight supported by beams, the weight being a movable portion, and a weight stopper that limits a movable range of the weight, the weight stopper being arranged in a vicinity of the weight with a given clearance and being a part of a substrate for the inertial sensor processed with MEMS techniques.

Claims

1. An inertial sensor comprising:

a sensing portion having a weight supported by beams, the weight being a movable portion; and

a weight stopper that limits a movable range of the weight,

the weight stopper being arranged in a vicinity of the weight with a given clearance and being a part of a substrate for the inertial sensor processed with MEMS techniques.

2. The inertial sensor as claimed in claim 1, wherein the weight stopper extends toward the weight from a frame that supports the beams, and partially covers gaps between the weight and the frame.

3. The inertial sensor as claimed in claim 1, wherein the weight stopper has a column portion for reinforcing strength of the weight stopper.

4. The inertial sensor as claimed in claim 1, wherein the substrate is made of silicon.

5. The inertial sensor as claimed in claim 4, wherein:

the substrate is an SOI substrate; and

the weight stopper is a part of a silicon film of the SOI substrate.

6. The inertial sensor as claimed in claim 1, wherein the weight stopper is provided on at least one of an inner surface of a cap covering the sensing portion and a bottom surface of a cavity in a package housing the sensing portion.

7. The inertial sensor as claimed in claim 6, further comprising spacers arranged at edges of the weight stopper to control the clearance.

8. The inertial sensor as claimed in claim 6, further comprising bumps arranged in a frame of the sensing portion to control the clearance.

9. The inertial sensor as claimed in claim 1, further comprising projections provided on at least one of a surface of the weight stopper facing the weight and the surface of the weight facing the weight stopper, to control the clearance.

10. The inertial sensor as claimed in claim 1, wherein the clearance is equal to or greater than the movable range of the weight, which corresponds to a dynamic range of the inertial sensor.

11. The inertial sensor as claimed in claim 1, further comprising a package on which the sensing portion is flip-chip mounted.