Reduction of the dynamic deformation of translational mirrors using inertial masses

• US 8,873,128 B2
• Filed: 07/06/2010
• Issued: 10/28/2014
• Est. Priority Date: 07/07/2009
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Technische Universitat Munchen
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Technische Universitat Munchen
• Inventors: Conrad, Holger, Grasshoff, Thomas, Jung, Denis, Sandner, Thilo
• Primary Examiner(s): Lester, Evelyn A.
• Application Number:
  US13/377,667
• Publication Number:
  US 20120099175A1
• Time in Patent Office: 1,575 Days
• Field of Search: 3592231-2262, 359290-295, 359/298
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A micromechanical mirror arrangement comprising a mirror plate (1) which forms a translation mirror, which is connected via at least one holding element (2), preferably two or more holding elements, to a frame structure (3) and is movable in translation relative to this frame structure, characterized in that the connection region (4) of at least one holding element (2), preferably of all holding elements, with the mirror plate (1) is arranged inwardly offset, viewed from the outer margin (5) of the mirror plate toward to the center (6) of the mirror plate.

Claims

1. A micromechanical mirror arrangement comprising

a mirror plate (1) formed as a translation mirror and connected by at least two holding elements (2) to a frame structure (3), said mirror plate movable in translation relative to this frame structure and arranged to reduce dynamic deformation of said mirror plate during the translation movement,

the mirror arrangement comprising,

said holding elements (2) connected to the mirror plate (1) at a connection region (4) which is arranged inwardly offset viewed from an outer margin (5) of the mirror plate toward the center (6) of the mirror plate;

said mirror plate (1) having inertial elements (7) which are arranged point-symmetrically to the center (6) of the mirror plate (1) and which project outwardly with respect to at least one connection region (4) of a holding element (2) with the mirror plate (1) viewed from the center (6) of the mirror plate (1) toward the outside.

2. A micromechanical mirror arrangement in accordance with claim 1, wherein the mean distance (E) of the outer margin (5) of the mirror plate (1) from its center (6) is greater than the spacing of the connection regions (4) of the holding elements (2) of the mirror plate (1) from this center (6).

3. A micromechanical mirror arrangement in accordance with claim 1, wherein the inertial elements (7) are arranged such that the perpendicular projection (P8) of the center (8) of these inertial elements (7) to a straight line (9) extending through the center (6) of the mirror plate (1) is further away from the center (6) of the mirror plate (1) than the perpendicular projection (P4) of the connection regions (4) of a holding element (2) with the mirror plate (1).

4. A micromechanical mirror arrangement in accordance with claim 1, further comprising a slot (10) arranged adjacent to at least one connection region (4) between the holding element (2) and the mirror plate (1) and is introduced, viewed from the outer margin (5) of the mirror plate inwardly to its center (6).

5. A micromechanical mirror arrangement in accordance with claim 1, wherein a section (11) of the mirror plate close to the center is connected to the inertial elements (7) of the mirror plate (1) via an offset frame element (12), with the frame element (12) being provided on its side facing the center (6) and on its side remote from the center (6), with a plurality of connection pieces (13) and that the frame element (12) is connected both to the section (11) close to the center and to the inertial elements (7).

6. A micromechanical mirror arrangement in accordance with claim 1, wherein said mirror plate (1) has a uniform thickness (D) viewed perpendicular to its plate plane between 10 nm and 500 μ

m.

7. A micromechanical mirror arrangement in accordance with claim 1, wherein said mirror plate (1) has sectionally different thicknesses (D1, D2), viewed perpendicular to its plate plane, with at least one of these thicknesses (D1, D2) being between 10 nm and 500 μ

m.

8. A micromechanical mirror arrangement in accordance with claim 1, wherein a section (11) of the mirror plate (1) facing the center (6) has a first thickness (D1) and the inertial elements (7) of the mirror plate have a second thickness (D2), with the first thickness (D1) being smaller than the second thickness (D2).

9. A micromechanical mirror arrangement in accordance with claim 1, wherein at least one of the holding elements (2) has the same thickness, viewed perpendicular to the plate plane of the mirror plate (1), as the inertial elements (7) of the mirror plate (1).

10. A micromechanical mirror arrangement in accordance with claim 1, wherein the inertial elements (7) of the mirror plate (1), viewed in the direction perpendicular to the plate plane of the mirror plate (1), have at least one additional inertial section (16) on at least one of the upper side and lower side (15).

11. A micromechanical mirror arrangement in accordance with claim 1, wherein a section (11) of the mirror plate (1) close to the center has at least one surface stiffening structure (17) on at least one of its upper side (14) and lower side (15).

12. A micromechanical mirror arrangement in accordance with claim 11, wherein the surface stiffening structure (17) is formed as a recess into at least one of the upper side (14) and lower side (15).

13. A micromechanical mirror arrangement in accordance with claim 1, wherein at least one section of the mirror plate (1) is a multilayer plate.

14. A micromechanical mirror arrangement in accordance with claim 13, wherein tensile stress is realized, viewed perpendicular to the plate plane of the mirror plate, on said multilayer plate.

15. A micromechanical mirror arrangement in accordance with claim 1, wherein said mirror plate (1) is formed with a lamella grid comb structure (19).

16. A micromechanical mirror arrangement in accordance with claim 15, wherein said comb structure (19) of the mirror plate (1) is formed as a comb drive.

17. A micromechanical mirror arrangement in accordance with claim 15, wherein the lamella grid is formed as an electrostatically, electromagnetically, piezoelectrically, piezomagnetically, electrostrictively, magnetostrictively, thermally or pneumatically drivable lamella grid.

18. A micromechanical mirror arrangement in accordance with claim 1, wherein said mirror plate (1) includes two beams (20a, 20b) which are arranged perpendicular to one another and which are provided with a plurality of comb fingers (21) of a comb structure (19) projecting perpendicular to the respective longitudinal axis of the beams.

19. A micromechanical mirror arrangement in accordance with claim 18, wherein said mirror plate (1) has a first beam (20a) and two further second beams (20b, 20c) arranged spaced apart from one another and parallel to one another, with the first beam (20a) being arranged perpendicular to the two second beams (20b, 20c), and with at least one beam (20a, 20b, 20c) being provided with a plurality of comb fingers (21) of a comb structure (19) projecting perpendicular to the respective longitudinal axis of the beam.

20. A micromechanical mirror arrangement in accordance with claim 1, wherein the inertial elements (7) of the mirror plate (1) are formed from a first material and a section (11) of the mirror plate (1) close to the center is formed from a second material.

21. A micromechanical mirror arrangement in accordance with claim 20, wherein at least one of the first material and the second material comprises one of amorphous, monocrystalline or polycrystalline silicon, silicon oxide, aluminum, aluminum oxide, aluminum nitride, titanium, titanium aluminide or titanium oxide.

22. A micromechanical mirror arrangement in accordance with claim 1, wherein said mirror plate (1) is monolithic.

23. A micromechanical mirror arrangement in accordance with claim 1, wherein at least one inertial element (7) of the mirror plate (1) is not mirror-coated and a section (11) of the mirror plate (1) close to the center (11) is mirror-coated.

24. A micromechanical mirror arrangement in accordance with claim 1, wherein at least one inertial element (7) of the mirror plate (1) is mirror-coated and is formed as a comb structure and a section (11) of the mirror plate (6) close to the center (11) is mirror-coated.

25. A micromechanical mirror arrangement in accordance with claim 1, wherein said holding elements (2) are one of bending beams, as meandering or beam spring elements and as a pantographic suspension.

26. A micromechanical mirror arrangement in accordance with claim 1, wherein at least one section (11) of the mirror plate (1) close to the center is made as a round, elliptical, rectangular or square plate section.

27. A micromechanical mirror arrangement in accordance with claim 1, wherein at least one projecting inertial element (7) of the mirror plate (1) is arranged at both ends (25a, 25b) of at least one beam (20, 20a, 20b, 20c).

28. A micromechanical mirror arrangement in accordance with claim 1 within a Fourier transform spectrometer.