Micro-machined mechanical structure and device incorporating the structure

• US 20020011117A1
• Filed: 04/23/2001
• Published: 01/31/2002
• Est. Priority Date: 04/28/2000
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Wehbe-Alause, Helene, Diem, Bernard, Lefort, Olivier, Orsier, Elisabeth
• Granted Patent: US 6,546,801 B2
• Time in Patent Office: Days
• US Class Current: 73/860
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2203/0307 Anchors
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• 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: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

A mechanical structure (100) comprises a moving mass (3) suspended by beams (4, 5, 6, 7) from a fixed frame (2). The structure (100) comprises elongation means (23-26) mechanically connected to each of the beams (4, 5, 6, 7). The elongation means is designed such that the stiffness of the beams (4, 5, 6, 7) varies only little during movement of the moving mass. The structure is characterized in that the response of an elongation means is asymmetric when acting in tension and in compression. The structure is thus made insensitive to accelerations along a direction parallel to the suspension direction.

Claims

1. Mechanical structure building in at least a moving mass moving along an OY axis, this moving mass being suspended by suspension elements mechanically connected firstly to the moving mass and secondly to fixed anchor means, the structure comprising an elongation means inserted between the anchor means and the moving mass and connected to each suspension element, this means co-operating with the suspension element to form an improved suspension means, with first ends mechanically connected to the anchor means and second ends connected to the moving mass, the elongation means being deformable in an XOY plane, the direction OX being the direction connecting the first end to the second end of the improved suspension means, structure characterised in that the stiffness of the elongation means is asymmetric, and an applied force causes a lower apparent stiffness variation when it is exerted in one direction along the OX axis than when the same force is applied in the opposite direction.

2. Structure according to claim 1, characterised in that at least one of the elongation means is in the form of at least one beam with two ends and an axial line with a hollow with a bottom, this beam being symmetrical with respect to an axis of the suspension element connected to it, such that the said axial line is in the form of two half parts symmetrical with each other, each half part having a point of inflection.

3. Structure according to claim 2, characterised in that the tangent to the axial line at each of its ends forms an angle of between 0 and 45°

with a direction perpendicular to the axis of symmetry of the axial line.

4. Structure according to claim 2, characterised in that the tangent to the axial line at the point of intersection of this line with the axis of symmetry is perpendicular to the axis of symmetry.

5. Structure according to claim 2, characterised in that an elongation means is connected to the anchor.

6. Structure according to claim 2, characterised in that an elongation means is connected to the moving mass.

7. Structure according to claim 2, characterised in that an elongation means is connected to the anchor, and in that an elongation means is connected to the moving mass.

8. Structure according to claim 5, characterised in that an elongation means is composed of several elongation beams.

9. Structure according to claim 6, characterised in that an elongation means is composed of several elongation beams.

10. Structure according to claim 7, characterised in that an elongation means is composed of several elongation beams.

11. Structure according to claim 1, characterised in that it comprises two improved suspension means symmetrical with each other about an axis.

12. Structure according to claim 2, characterised in that it comprises two improved suspension means symmetrical with each other about an axis.

13. Structure according to claim 1, characterised in that it comprises four improved suspension means symmetrical with each other in pairs.

14. Structure according to claim 2, characterised in that the axial line of at least one of the elongation means is in the form of a hollow, the bottom of which consists of a straight line segment.

15. Device, and particularly a sensor, incorporating a mechanical structure according to any one of claims 1 to 14.