Acceleration sensor structure and use thereof

• US 9,279,825 B2
• Filed: 01/11/2013
• Issued: 03/08/2016
• Est. Priority Date: 01/12/2012
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Electronics OY (Murata Manufacturing Co Limited)
• Inventors: Blomqvist, Anssi, Roschier, Leif, RYTKONEN, Ville Pekka
• Primary Examiner(s): Noori, Max
• Application Number:
  US13/739,513
• Publication Number:
  US 20130192371A1
• Time in Patent Office: 1,152 Days
• Field of Search: 735/143.2, 737/77
• US Class Current: 1/1
• CPC Class Codes: G01P 1/00 Details of instruments
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: G01P 15/02 by making use of inertia forces using solid seismic massesG01P15/14 takes precedence
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• 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

Abstract

A MEMS-sensor structure comprising first means and second means coupled for double differential detection and positioned symmetrically to provide quantities for the double differential detection in a phase shift. If the sensor deforms, due to a specifically symmetric positioning of the first and second means, the effect of the displacement is at least partly eliminated.

Claims

1. A sensor structure matrix comprising a first sensor cell, a second sensor cell and a third sensor cell, each of the sensor cells having a planar structure, the first sensor cell including a MEMS-sensor structure that comprises:

a first proof mass configured to pivot around an axis of rotation to provide a first differentially coupled pair of detectable quantities including a diminishing first quantity at a first location and an increasing second quantity at a second location mutually coupled so that said diminishing and increasing occur because of the same operation; and

a second proof mass configured to pivot around the axis of rotation to provide a second differentially coupled pair of quantities including a diminishing third quantity at a third location and an increasing fourth quantity at a fourth location mutually coupled so that said diminishing and increasing occur because of the same operation,

wherein the first proof mass and the second proof mass are coupled for double differential detection and positioned symmetrically to generate quantities for the double differential detection in a phase shift;

wherein the first sensor cell, the second sensor cell and the third sensor cell are arranged into a common plane,

wherein the second cell and the third sensor cell are arranged to detect acceleration components in the common plane,

wherein the second sensor cell and the third sensor cell are arranged into parallel positions along a first direction in the common plane,

wherein the first sensor cell is arranged to a parallel position between the second sensor cell and the third sensor cell in said common plane such that the axis of rotation of the first sensor cell is parallel to the first direction,

wherein the first proof mass of the first cell includes an end part that extends beyond the dimension of the second sensor cell and the third sensor cell in a second direction, and to the outer ends of the second sensor cell and the third sensor cell in the first direction, wherein the second direction is perpendicular to the first direction,

wherein the second proof mass of the first cell includes an end part that extends beyond the dimension of the second sensor cell and the third sensor cell in the second direction, and to the outer ends of the second sensor cell and the third sensor cell in the first direction, and

wherein the end part of the first proof mass and the end part of the second proof mass are on different sides of the axis of rotation.

2. The sensor structure matrix of claim 1, wherein the phase shift is 180°

causing the first proof mass and the second proof mass to provide quantities for the double differential detection in opposite phase.

3. The sensor structure matrix of claim 1, the second sensor cell or the third sensor cell including:

a frame suspendable to a substrate with one or more springs;

first capacitive elements supported by the frame;

an anchor element for connection to the substrate;

second capacitive elements supported by the anchor element;

wherein

the detectable quantities are capacitances between the first capacitive elements and the second capacitive elements, the capacitances varying according to movements of the frame in respect of the substrate.

4. The sensor structure matrix of claim 3, wherein the second sensor cell and the third sensor cell are arranged into a XY-directional planar structure in the common plane, and a proof mass of the second sensor cell and a proof mass of the third sensor cell are oriented to detect accelerations in X-direction, in Y-direction, or in X-direction and in Y-direction of the XY-directional structure.

5. The sensor structure matrix of claim 1, wherein:

the first proof mass is coupled to a first spring structure to pivot around the axis of rotation;

the second proof mass is coupled to a second spring structure to pivot around the axis of rotation.

6. The sensor structure matrix of claim 5, wherein the mass distributions of the first proof mass and the second proof mass of the first sensor cell are point symmetrical.

7. The MEMS-sensor structure of claim 6, wherein the first spring structure and the second spring structure are coupled to a single anchor for connection to a substrate.

8. A sensor structure matrix of claim 4, comprising at least one sensor cell for detection in the X-direction and at least one sensor cell for detection in the Y-direction.

9. An acceleration sensor comprising the sensor structure matrix of claim 1.

10. A device (D) comprising an acceleration sensor of claim 9, wherein said device comprises at least one of the following:

a vehicle, cloth, shoe, pointer, compass, scales, seismometer, navigator, mobile device, mechanical motor, hydraulic motor, electric motor, generator, bearing module, centrifuge.

11. A system comprising at least one device of claim 10.