ACCELERATOR SENSOR STRUCTURE AND USE THEREOF

• US 20130192371A1
• Filed: 01/11/2013
• Published: 08/01/2013
• 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
• Granted Patent: US 9,279,825 B2
• Time in Patent Office: Days
• US Class Current: 73/514.32
• 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 MEMS-sensor structure, comprising:

first means for providing 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,

second means for providing 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

the first means and the second means being coupled for double differential detection and positioned symmetrically to generate quantities for the double differential detection in a phase shift.

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

causing the first differentially coupled pair and the second differentially coupled pair to provide quantities for the double differential detection in opposite phase.

3. The MEMS-sensor structure of claim 1, 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;

the second capacitive elements comprise the first means and the second means.

4. The MEMS-sensor structure of claim 3, wherein the first and the second means are arranged into a XY-directional planar structure and the first and the second means are oriented to detect accelerations in X-direction or in Y-direction of the XY-directional structure.

5. The MEMS-sensor structure of claim 1, including:

a first proof mass coupled to a first spring to pivot around an axis of rotation;

a second proof mass coupled to a second spring to pivot around the axis of rotations;

a first pair of opposite capacitive elements supported on the first proof mass;

a second pair of opposite capacitive elements supported on the second proof mass;

one or more static electrodes;

wherein

the first differentially coupled pair of detectable quantities are capacitances generated by the first pair of opposite capacitive elements, and the second differentially coupled pair of detectable quantities are capacitances generated by the second pair of opposite capacitive elements.

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

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

8. A sensor structure matrix comprising at least one sensor structure of claim 1.

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

10. A sensor structure matrix of claim 8, comprising two sensor structures for detection in the X-direction and two sensor structures for detection in the Y-direction.

11. A sensor structure matrix of claim 10, comprising sensor structures including:

first means for providing 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,

second means for providing 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

the first means and the second means being coupled for double differential detection and positioned symmetrically to generate quantities for the double differential detection in a phase shift,

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;

the second capacitive elements comprise the first means and the second means.

12. An accelerator sensor comprising at least one sensor structure of claim 1.

13. A device (D) comprising an accelerator sensor of claim 12, 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.

14. A system comprising at least one device of claim 13.