Micromachined electrothermal rotary actuator

• US 8,243,397 B2
• Filed: 06/20/2007
• Issued: 08/14/2012
• Est. Priority Date: 06/20/2007
• Status: Active Grant

• Current Assignee: Carnegie Mellon University
• Original Assignee: Carnegie Mellon University
• Inventors: Messner, William C., Bain, James A., Fedder, Gary K.
• Primary Examiner(s): Castro, Angel A.
• Application Number:
  US11/820,628
• Publication Number:
  US 20080314040A1
• Time in Patent Office: 1,882 Days
• Field of Search: 360/294.3, 310/306, 605/28
• US Class Current: 360/294.3
• CPC Class Codes: F03G 7/06 using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like using thermal expansion of non-vaporising liquids F01K
• CPC Class Codes: F05B 2250/82 Micromachines

Abstract

The present disclosure is directed to a micromachined rotary actuator constructed of a central portion and an outer portion at least partially surrounding the central portion and separated from the central portion by an in-plane gap. A plurality of arms are each connected at one end to the central portion and at another end to the outer portion so as to span the in-plane gap. The arms are constructed of a plurality of horizontally stacked materials positioned to enable the arms to bend in-plane when heated. Conductors are positioned within the actuator for heating the arms. Because of the rules governing abstracts, this abstract should not be used to construe the claims.

Claims

1. A micromachined rotary actuator, comprising:

a central portion;

an outer portion at least partially surrounding said central portion and separated from said central portion by an in-plane gap;

a plurality of arms each connected at one end to said central portion and at another end to said outer portion so as to span said in-plane gap, each arm being comprised of a plurality of different horizontally stacked materials laterally offset in the same plane positioned to enable each arm to bend in-plane when heated; and

conductors for heating said arms.

2. The actuator of claim 1 wherein said central portion is circular in shape and said outer portion completely surrounds said central portion to define a disk-shaped, in-plane gap between said central portion and said outer portion.

3. The actuator of claim 2 wherein said arms are radially aligned.

4. The actuator of claim 1 wherein said plurality of arms extends substantially perpendicularly from each of said central portion and said outer portion.

5. The actuator of claim 1 wherein said plurality of arms extends at an angle from each of said central portion and said outer portion.

6. The actuator of claim 1 wherein said heating conductors are positioned in one or more of said plurality of arms, said central portion, and said outer portion.

7. The actuator of claim 6 wherein said heating conductors are connected so as to be energized one of individually, in groups, or altogether.

8. The actuator of claim 1 wherein said arms have one of a rectangular or trapezoidal cross section.

9. A head assembly for a disk drive, comprising:

a micromachined rotary actuator having a stationary portion configured for connection to a flexure and a moving portion capable of providing rotary motion with respect to said stationary portion;

wherein said actuator comprises a plurality of arms each connected at one end to a central portion and at another end to an outer portion so as to span an in-plane gap, each arm being comprised of a plurality of different horizontally stacked materials laterally offset in the same plane positioned to enable said arms to bend in-plane when heated;

a slider connected to said moving portion; and

a transducer head carried by said slider.

10. The head assembly of claim 9,

wherein said outer portion at least partially surrounds said central portion and is separated from said central portion by said in-plane gap;

wherein said actuator comprises conductors for heating said arms.

11. The head assembly of claim 10 wherein said central portion is said stationary portion and said outer portion is said moving portion.

12. The head assembly of claim 10 wherein said outer portion is said stationary portion and said central portion is said moving portion.

13. The actuator of claim 10 wherein said central portion is circular in shape and said outer portion completely surrounds said central portion to define a disk-shaped, in-plane gap between said central portion and said outer portion.

14. The actuator of claim 13 wherein said arms are radially aligned.

15. The actuator of claim 10 wherein said plurality of arms extends substantially perpendicularly from each of said central portion and said outer portion.

16. The actuator of claim 10 wherein said heating conductors are positioned in one or more of said plurality of arms, said central portion, and said outer portion.

17. The actuator of claim 16 wherein said heating conductors are connected so as to be energized one of individually, in groups, or altogether.

18. The actuator of claim 17 wherein said arms have one of a rectangular or trapezoidal cross section.

19. The actuator of claim 10 wherein said arms are constructed to transmit a load from said flexure to said slider.

20. The head assembly of claim 9 wherein each of said arms comprises a plurality of horizontally stacked materials having different coefficients of thermal expansion.

21. A method of providing in plane rotary motion with a micromachined rotary actuator, comprising:

providing a central portion;

providing an outer portion at least partially surrounding said central portion and separated from said central portion by an in-plane gap;

providing a plurality of arms each connected at one end to said central portion and at another end to said outer portion so as to span said in-plane gap, said arms comprised of a plurality of horizontally stacked materials positioned to enable said arms to bend in-plane when heated; and

supplying current to conductors within the rotary actuator for heating said arms.

22. The method of claim 21 additionally comprising monitoring the temperature of the rotary actuator, and wherein said supplying step is responsive to a monitored temperature.

23. The method of claim 21 additionally comprising monitoring the position of the rotary actuator, and wherein said supplying step is responsive to a monitored position.

24. The method of claim 23 wherein said arms are heated so as to obtain rotary motion in one of discrete steps or continuous motion.

25. A micromachined rotary actuator, comprising:

a central portion;

an outer portion at least partially surrounding said central portion and separated from said central portion by an in-plane gap;

a plurality of arms each connected at one end to said central portion and at another end to said outer portion so as to span said in-plane gap, each arm being comprised of a plurality of different horizontally stacked materials having different coefficients of thermal expansion positioned to enable each arm to bend in-plane when heated; and

conductors for heating said arms.

26. A head assembly for a disk drive, comprising:

a micromachined rotary actuator having a stationary portion configured for connection to a flexure and a moving portion capable of providing rotary motion with respect to said stationary portion;

wherein said actuator comprises a plurality of arms each connected at one end to a central portion and at another end to an outer portion so as to span an in-plane gap, each arm being comprised of a plurality of different horizontally stacked materials having different coefficients of thermal expansion positioned to enable each arm to bend in-plane when heated;

a slider connected to said moving portion; and

a transducer head carried by said slider.