Device for measuring magnetic fields with Laplace force

Patent metadata

Field	Value
Publication number	US-9417097-B2
Application number	US-201314423831-A
Country	US
Kind code	B2
Filing date	Aug 29, 2013
Priority date	Aug 29, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A device for measuring magnetic fields with Laplace force, comprising a substrate extending in a substrate plane, a first rigid frame in a first plane moveable relative to the substrate about a first rotation axis parallel to the substrate plane with a central through-recess. There is a fixed electrical conductor wound an axis perpendicular to the plane of the first frame. There a first hinge connecting the first rigid frame to the substrate with a first electrical track. There is a second hinge connected to the first rigid frame with a second electrical track. There is a first sensor for measuring of the angular displacement of the first rigid frame. The first hinge and the first electrical track are inside the central recess of the first rigid frame and the second hinge and the second electrical track are outside the central recess of the first rigid frame.

First claim

The invention claimed is:

1. A device for measuring magnetic fields with Laplace force, this device comprising:
a substrate extending essentially in a plane called the “plane of the substrate”,
a first rigid frame extending essentially in a plane called the “plane of the first frame” and suspended above the substrate, the first frame being moveable relative to the substrate in rotation about a first rotation axis parallel to the plane of the substrate, and the first rigid frame comprising a central through-recess,
a fixed electrical conductor fixed, with no degree of freedom, to the first rigid frame, the fixed electrical conductor being wound about a winding axis perpendicular to the plane of the first frame,
at least one first hinge mechanically connecting the first rigid frame to the substrate, the at least one first hinge comprising a first electrical track electrically connecting a first end of the fixed electrical conductor and a first connection pad fixedly attached to the substrate,
a second hinge mechanically connected to the first rigid frame and comprising a second electrical track electrically connecting a second end of the fixed electrical conductor to a second connection pad fixedly attached to the substrate, and
at least one first sensor capable of measuring a physical quantity representing the amplitude of the angular displacement of the first rigid frame about said first rotation axis, wherein:
the at least one first hinge and the first electrical track are situated inside the central recess of the first rigid frame, and
the second hinge and the second electrical track are situated outside the central recess of the first rigid frame.

2. The device according to claim 1 , wherein the at least one first sensor is a strain sensor, and the strain sensor comprises a beam, a first end of which is directly anchored in the first rigid frame and a second end of which is anchored, with no degree of freedom, to the substrate, the first end being anchored in the first rigid frame, at a non-zero distance dp from the first rotation axis, this distance dp being at least twice as small as the thickness of the first frame and the thickness of the beam being at least twice as small as the thickness of the first rigid frame.

3. The device according to claim 2 , wherein the beam is entirely disposed beneath a plane parallel to the plane of the substrate and passing through the rotation axis.

4. The device according to claim 2 , wherein the first rigid frame comprises at least one rigid lateral branch extending along the first rotation axis and the beam is suspended above the substrate, the beam extends perpendicularly to the first rotation axis essentially in a plane parallel to the plane of the substrate and the first end being:
situated strictly above or strictly beneath a plane passing through the first rotation axis and parallel to the plane of the substrate, and
directly fixed to the lateral branch.

5. The device according to claim 4 , wherein the lateral branch comprises a notch extending perpendicularly to the first rotation axis until a bottom, and the first end of the beam is directly fixed with no degree of freedom to this bottom.

6. The device according to claim 2 , wherein the beam of the sensor is made out of piezoelectrical material and the sensor comprises means capable of measuring a physical quantity representing the variation of the resistance of the beam in response to the rotation of the first rigid frame.

7. The device according to claim 2 , wherein the sensor comprises:
a first electrode capable of making the beam vibrate,
a second electrode, wherein the first or second electrodes measure the vibration of the beam,
means capable of measuring a physical quantity representing the vibration frequency of the beam, and
a source for powering the first and second electrodes capable of automatically slaving the vibration frequency of the beam to the mechanical resonance frequency of the beam.

8. The device according to claim 1 , wherein the center of gravity of the first rigid frame is contained in a plane perpendicular to the plane of the first rigid frame and containing the first rotation axis.

9. The device according to claim 1 , wherein the first rigid frame comprises a first rigid arm and a second rigid arm that are parallel, situated on either side of the central recess passing through the first rigid frame, and the second hinge mechanically connects the first rigid frame to the substrate, the first and second hinges being mechanically connected directly, respectively, to the first and second arms.

10. The device according to claim 1 , wherein the first connection pad is situated outside the first rigid frame and the device comprises an electrical track passing beneath the first rigid frame and electrically linking the first electrical track of the first hinge to the connection pad fixedly attached to the substrate situated outside the rigid frame.

11. The device according to claim 1 , further comprising:
a second rigid frame extending essentially in a plane and suspended above the substrate, the second rigid frame being moveable relative to the substrate in rotation about a second rotation axis parallel to the plane of the substrate and not parallel to the first rotation axis, the second rigid frame comprising a central recess inside which the first rigid frame is received,
at least one third hinge mechanically connecting the second rigid frame to the substrate,
at least one second sensor capable of measuring a physical quantity representing the amplitude of the angular displacement of the second rigid frame about the second rotation axis, and
the second hinge is suspended above the substrate and fixed, on one side, to the first rigid frame and, on an opposite side, to the second rigid frame, the second hinge being shaped to allow the rotation of the first rigid frame about the first rotation axis and keep the first rigid frame suspended above the substrate.

12. The device according to claim 1 , wherein the winding axis passes through the central recess.

13. The device according to claim 1 , wherein each of the first and second hinges enable the rotation of the first rigid frame about the first rotation axis comprises a torsion bar which extends along the first rotation axis, the torsion bar being shaped so as to be deformed essentially in torsion during the rotation of the first rigid frame.

14. The device according to claim 1 , wherein the electrical conductor is wound several times about the first winding axis to form a coil with several turns.

Assignees

• Commissariat L Energie Atomique Et Aux Energies Alternatives

Inventors

• Robert Philippe
• Ettelt Dirk
• Walther Arnaud

Classifications

• G01R33/038

  using permanent magnets, e.g. balances, torsion devices · CPC title

• G01D5/14 Primary

  influencing the magnitude of a current or voltage · CPC title

• G01R33/0286 Primary

  comprising microelectromechanical systems [MEMS] (MEMS devices in general B81B) · CPC title