Acceleration sensor

• US 8,368,387 B2
• Filed: 10/28/2008
• Issued: 02/05/2013
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Konno, Nobuaki
• Primary Examiner(s): TANG, MINH NHUT
• Application Number:
  US12/920,682
• Publication Number:
  US 20110031959A1
• Time in Patent Office: 1,561 Days
• Field of Search: None
• US Class Current: 324/162
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 7/0048 between the MEMS die and the substrate
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/0888 for indicating angular acceleration
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/14 by making use of gyroscopes gyroscopes per se G01C19/00
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration
• CPC Class Codes: G01P 3/22 transferred to the indicator by electric or magnetic means
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

An acceleration sensor includes a substrate, first and second torsion beams, first and second detection frames, first and second detection electrodes, first and second link beams, and an inertial mass body. The first and second torsion beams are distorted around the first and second torsion axes. The first and second detection frames are rotated about the first and second torsion axes. The first and second detection electrodes detect an angle formed between the substrate and each of the first and second detection frames. The first link beam is on a first axis located at a position shifted from a position of the first torsion axis to one end side of the first detection frame along a direction crossing the first torsion axis. The second link beam is on a second axis located at a position shifted from a position of the second torsion axis in a direction identical to the direction of shift from the position of the first torsion axis.

Claims

1. An acceleration sensor, comprising:

a substrate;

a first torsion beam supported by said substrate to be distorted around a first torsion axis;

a first detection frame supported by said substrate via said first torsion beam so as to be rotatable about said first torsion axis;

a second torsion beam supported by said substrate to be distorted around a second torsion axis;

a second detection frame supported by said substrate via said second torsion beam so as to be rotatable about said second torsion axis;

first and second detection electrodes formed on said substrate so as to face said first and second detection frames, respectively, for detecting an angle formed between said substrate and each of said first and second detection frames on the basis of electrostatic capacitance;

a first link beam connected to said first detection frame on a first axis located at a position shifted from a position of said first torsion axis to one end side of said first detection frame along a direction crossing said first torsion axis;

a second link beam connected to said second detection frame on a second axis located at a position shifted from a position of said second torsion axis in a direction identical to the direction of shift from the position of said first torsion axis; and

an inertia mass body supported above said substrate to be displaceable in a thickness direction of said substrate, by being linked with said first and second detection frames by said first and second link beams, respectively.

2. The acceleration sensor according to claim 1, wherein an offset between said first torsion axis and said first link beam is equal to an offset between said second torsion axis and said second link beam.

3. The acceleration sensor according to claim 1, wherein said first torsion axis and said second torsion axis are in parallel with each other.

4. The acceleration sensor according to claim 1, wherein said first and second detection frames, said first and second torsion beams, and said first and second link beams are disposed to be symmetrical with respect to an axis in parallel with said first and second torsion axes.

5. The acceleration sensor according to claim 4, wherein said first and second detection frames, said first and second torsion beams, and said first and second link beams are disposed to be symmetrical with respect to an axis crossing said first and second torsion axes.

6. The acceleration sensor according to claim 5, further comprising detection frames, torsion beams, and link beams implemented by rotating said first and second detection frames, said first and second torsion beams, and said first and second link beams by 90 degrees, respectively.

7. The acceleration sensor according to claim 1, further comprising:

a third torsion beam supported by said substrate to be distorted around a third torsion axis;

a third detection frame supported by said substrate via said third torsion beam so as to be rotatable about said third torsion axis;

a fourth torsion beam supported by said substrate to be distorted around a fourth torsion axis;

a fourth detection frame supported by said substrate via said fourth torsion beam so as to be rotatable about said fourth torsion axis;

third and fourth detection electrodes formed on said substrate so as to face said third and fourth detection frames, respectively, for detecting an angle formed between said substrate and each of said third and fourth detection frames on the basis of electrostatic capacitance;

a third link beam connected to said third detection frame on a third axis located at a position shifted from a position of said third torsion axis to one end side of said third detection frame along a direction crossing said third torsion axis; and

a fourth link beam connected to said fourth detection frame on a fourth axis located at a position shifted from a position of said fourth torsion axis in a direction identical to the direction of shift from the position of said third torsion axis,

wherein a direction of shift from said third and fourth torsion axes to said third and fourth axes is opposite to a direction of shift from said first and second torsion axes to said first and second axes.