Microelectromechanical magnetic switches having rotors that rotate into a recess in a substrate

• US 7,432,788 B2
• Filed: 06/03/2004
• Issued: 10/07/2008
• Est. Priority Date: 06/27/2003
• Status: Active Grant

• Current Assignee: Memscap Incorporated
• Original Assignee: Memscap Incorporated
• Inventors: Wood, Robert L., Glukh, Konstantin, Agrawal, Vivek
• Primary Examiner(s): Enad; Elvin
• Assistant Examiner(s): Rojas; Bernard
• Application Number:
  US10/859,633
• Publication Number:
  US 20040263297A1
• Time in Patent Office: 1,587 Days
• Field of Search: 335/78, 200/181
• US Class Current: 335/78
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 2001/0047 operable only by mechanical latching
• CPC Class Codes: H01H 2036/0093 Micromechanical switches actuated by a change of the magnetic field
• CPC Class Codes: H01H 36/00 Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding

Abstract

A magnetic switch includes a substrate having a recess therein. A rotor or rotors are provided on the substrate. The rotor includes a tail portion that overlies the recess, and a head portion that extends on the substrate outside the recess. The rotor may be fabricated from ferromagnetic material, and is configured to rotate the tail in the recess in response to a changed magnetic field. First and second magnetic switch contacts also are provided that are configured to make or break electrical connection between one another in response to rotation of the tail in the recess, in response to the changed magnetic field. Related operation and fabrication methods also are described.

Claims

1. A magnetic switch comprising:

a substrate including therein a recess;

a rotor that includes a tail portion that overlies the recess and a head portion that extends on the substrate outside the recess, the rotor comprising unmagnetized ferromagnetic material, being configured to rotate the tail in the recess in response to a changed magnetic field and the rotor being balanced in relation to a torsional hinge used to mount the rotor to the substrate;

first and second magnetic switch contacts that are configured to make or break electrical connection between one another in response to rotation of the tail in the recess in response to the changed magnetic field, and

at least one deformable beam having a fixed end attached to the substrate and a movable end extending beneath the head portion to allow for contact with the head portion in its rest position and/or to provide the torsional hinge with mechanical bias.

2. A magnetic switch according to claim 1

wherein the torsional hinge defines an axis about which the tail is configured to rotate in the recess in response to the changed magnetic field, and

wherein the torsional hinge is prestressed during a mechanical assembly process that provides an initial tilt to the rotor.

3. A magnetic switch according to claim 2 wherein the recess includes a wall that intersects with the substrate at the axis.

4. A magnetic switch according to claim 1 wherein the first contact is on the head portion and the second contact is on the substrate adjacent the head portion.

5. A magnetic switch according to claim 1 wherein the first contact is on the tail portion and the second contact is in the recess adjacent the tail portion.

6. A magnetic switch according to claim 1 further comprising a cap on the substrate that is spaced apart from the rotor to allow rotation thereof, and wherein the first contact is on the head portion and the second contact is on the cap adjacent the head portion.

7. A magnetic switch according to claim 1 further comprising a cap on the substrate that is spaced apart from the rotor to allow rotation thereof, and wherein the first contact is on the tail portion and the second contact is on the cap adjacent the tail portion.

8. A magnetic switch according to claim 1 wherein the first contact and the second contact are on the substrate adjacent the head portion.

9. A magnetic switch according to claim 1 wherein the first contact and the second contact are in the recess adjacent the tail portion.

10. A magnetic switch according to claim 1 further comprising a cap on the substrate that is spaced apart from the rotor to allow rotation thereof, and wherein the first contact and the second contact are on the cap adjacent the head portion.

11. A magnetic switch according to claim 1 further comprising a cap on the substrate that is spaced apart from the rotor to allow rotation thereof, and wherein the first contact and the second contact are on the cap adjacent the tail portion.

12. A magnetic switch according to claim 4 further comprising:

first and second conductors that extend through the substrate, a respective one of the first and second conductors being electrically connected to a respective one of the first and second contacts, to provide external contacts for the magnetic switch on the substrate.

13. A magnetic switch according to claim 5 further comprising:

first and second conductors that extend through the substrate, a respective one of the first and second conductors being electrically connected to a respective one of the first and second contacts, to provide external contacts for the magnetic switch on the substrate.

14. A magnetic switch according to claim 6 further comprising:

a first conductor that extends through the substrate and is electrically connected to the first contact, to provide an external contact for the magnetic switch on the substrate; and

a second conductor on the cap that is electrically connected to the second contact to provide an external contact for the magnetic switch on the cap.

15. A magnetic switch according to claim 7 further comprising:

a first conductor that extends through the substrate and is electrically connected to the first contact, to provide an external contact for the magnetic switch on the substrate; and

a second conductor on the cap that is electrically connected to the second contact to provide an external contact for the magnetic switch on the cap.

16. A magnetic switch according to claim 8 further comprising:

first and second conductors that extend through the substrate, a respective one of the first and second conductors being electrically connected to a respective one of the first and second contacts, to provide external contacts for the magnetic switch on the substrate.

17. A magnetic switch according to claim 9 further comprising:

first and second conductors that extend through the substrate, a respective one of the first and second conductors being electrically connected to a respective one of the first and second contacts, to provide external contacts for the magnetic switch on the substrate.

18. A magnetic switch according to claim 10 further comprising first and second electrical conductors on the cap, a respective one of which is electrically connected to a respective one of the first and second contacts, to provide external contacts for the magnetic switch on the cap.

19. A magnetic switch according to claim 11 further comprising first and second electrical conductors on the cap, a respective one of which is electrically connected to a respective one of the first and second contacts, to provide external contacts for the magnetic switch on the cap.

20. A magnetic switch according to claim 1 wherein the first and/or second contacts are on the substrate outside the head portion and are configured to move beneath the head portion.

21. A magnetic switch according to claim 1 wherein at least a portion of the first and/or second contacts are connected to the movable end.

22. A magnetic switch according to claim 1 comprising first and second deformable beams, the movable ends being connected to the first contact, the first and/or second beams being configured to move, upon application of heat thereto, the first contact beneath the head portion.

23. A magnetic switch according to claim 21, wherein the first contact remains beneath the head portion.

24. A magnetic switch according to claim 1, wherein the movable end is connectedto the first contact, and wherein the movable end is configured to move the first contact beneath the head portion.

25. A magnetic switch according to claim 1, wherein the movable end is connected to the first contact and wherein the beam is configured to inelastically deform to move the first contact beneath the head portion and cause the first contact to remain beneath the head portion.

26. A magnetic switch according to claim 20 further comprising an actuator on the substrate that is configured to move the first and/or second contacts beneath the head portion.

27. A magnetic switch according to claim 1 wherein the torsional hinge is configured to provide a small lateral motion to the rotor in addition to rotating the tail in the recess wherein such lateral motion result is in a wiping of the first and/or second contacts in response to the changed magnetic field.

28. A magnetic switch according to claim 1 wherein the rotor is a first rotor, the magnetic switch further comprising:

a second rotor that includes a second tail portion that overlies the recess and a head portion that extends on the substrate outside the recess, the second rotor comprising ferromagnetic material and being configured to rotate the tail in the recess in response to the changed magnetic field.

29. A magnetic switch according to claim 28 further comprising:

a first hinge that is coupled to the first rotor to define an axis about which the tail is configured to rotate in response to the changed magnetic field; and

a second hinge that is coupled to the second rotor along the axis, and which is stiffer than the first hinge, such that the first and second rotors rotate at different speeds in response to the changed magnetic field.

30. A magnetic switch according to claim 29 further comprising a common hinge that is coupled between the first and second rotors and extends about the axis.

31. A magnetic switch according to claim 30 wherein the first and second hinges are conductive and the common hinge is insulating.

32. A magnetic switch according to claim 29 wherein the first and second magnetic contacts are configured to provide a complex switching operation, a make-before-break or a break-before make operation in response to rotation of the first and second rotors.

33. A magnetic switch according to claim 1 in combination with:

a housing; and

a permanent magnet that is coupled to the housing;

the magnetic switch being removably coupled to the housing and configured such that removal of the magnetic switch from the housing causes the first and second magnetic switch contacts to make or break electrical connection between one another.

34. A magnetic switch according to claim 1 in combination with:

an electrical device that is electrically connected to the first and/or second contacts and is configured to become operative upon the first and second magnetic switch contacts making or breaking electrical connection between one another.

35. A magnetic switch according to claim 34 in further combination with an encapsulating structure, and wherein the substrate and the electrical device are encapsulated by the encapsulating structure.

36. A magnetic switch according to claim 1 further comprising:

a permanent magnet that generates a constant magnetic field to maintain the rotor in a predetermined position, the rotor being configured to rotate from the predetermined position in response to the changed magnetic field.

37. A magnetic switch according to claim 1 further comprising:

at least one mechanical stop attached to the substrate in a way that limits the motion of the deformable beam; and

a latch that is configured to maintain position of the deformable beam touching the mechanical stop.

38. A magnetic switch according to claim 37 wherein the latch comprises a snapping tether that is coupled to the deformable beam to allow its movable end to extend beneath the head portion.

39. A magnetic switch comprising:

a substrate including therein a recess;

a rotor that includes a tail portion that overlies the recess and a head portion that extends on the substrate outside the recess, the head portion and the tail portion of the rotor comprising ferromagnetic material and being configured to rotate the tail in the recess in response to a changed magnetic field the rotor being balanced in relation to a torsional hinge used to mount the rotor to the substrate; and

first and second magnetic switch contacts that are configured to make or break electrical connection between one another in response to rotation of the tail in the recess in response to the changed magnetic field, and

at least one deformable beam having a fixed end attached to the substrate and a movable end extending beneath the head portion to allow for contact with the head portion in its rest position and/or to provide the torsional hinge with mechanical bias.

40. A magnetic switch comprising:

a substrate including therein a recess;

a rotor connected to the substrate by torsional hinge means for mechanically biasing the rotor to a first position in relation to the substrate in the absence of a magnetic field, the rotor being balanced in relation to the torsional hinge, the rotor including a tail portion that overlies the recess and a head portion that extends on the substrate outside the recess, the rotor comprising unmagnetized ferromagnetic material and being configured to rotate the rotor to a second position in response to a changed magnetic field, the tail being in the recess when the rotor is in the second position; and

first and second magnetic switch contacts that are configured to make or break electric connection between one another in response to rotation of the tail in the recess in response to the changed magnetic field, and

at least one deformable beam having a fixed end attached to the substrate and a movable end extending beneath the head portion to allow for contact with the head portion in its rest position and/or to provide the torsional hinge with mechanical bias.