Piezoelectric actuator

• US 5,939,816 A
• Filed: 06/24/1994
• Issued: 08/17/1999
• Est. Priority Date: 09/30/1988
• Status: Expired due to Fees

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Culp, Gordon W.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US08/265,561
• Time in Patent Office: 1,880 Days
• Field of Search: 310/323, 310/328, 310/366, 310/317, 310/316, 310/319
• US Class Current: 310/328
• CPC Class Codes: H02N 2/0095 producing combined linear and rotary motion, e.g. multi-direction positioners
• CPC Class Codes: H02N 2/021 using intermittent driving, e.g. step motors, piezoleg motors
• CPC Class Codes: H02N 2/028 along multiple or arbitrary translation directions, e.g. XYZ stages
• CPC Class Codes: H02N 2/101 using intermittent driving, e.g. step motors
• CPC Class Codes: H02N 2/108 around multiple axes of rotation, e.g. spherical rotor motors
• CPC Class Codes: H02N 2/142 Small signal circuits; Means for controlling position or derived quantities, e.g. speed, torque, starting, stopping, reversing
• CPC Class Codes: H10N 30/101 with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• CPC Class Codes: H10N 30/1071 with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• CPC Class Codes: H10N 30/2023 having polygonal or rectangular shape

Abstract

A piezoelectric device or actuator (30) includes dimorph stack (32) attached to a support (34). Affixed to the apex of stack (32) is friction surface (36) which is held in contact with the external friction surface of a positionable object (38).

Claims

1. A piezoelectric actuator capable of providing independently controllable motion in first and second angularly disposed planes, comprising:

a first piezoelectric dimorph having a pair of ground electrodes and an active electrode oriented so as to cause an electrical potential across said piezoelectric portion and move said first piezoelectric dimorph in said first plane;

a second piezoelectric dimorph acting in said second plane angularly with respect to the first plane, and said second piezoelectric dimorph being in direct physical and conductive electrical contact with a ground electrode of said first piezoelectric dimorph; and

means for independently controlling an electric field in each of said first and said second piezoelectric dimorphs to produce said independent movement in said first and second piezoelectric dimorphs.

2. The piezoelectric actuator of claim 1 wherein first and second piezoelectric dimorphs act in orthogonally disposed planes.

3. The piezoelectric actuator of claim 1 wherein one piezoelectric dimorph is a lifter acting in thickness mode and the other piezoelectric dimorph acts in a shear mode.

4. The piezoelectric actuator of claim 1 wherein said first piezoelectric dimorph comprises a plurality of first piezoelectric dimorphs each in direct conductive electrical contact with the adjacent dimorph and all providing motion in the same planar direction.

5. The piezoelectric actuator of claim 4 wherein said second piezoelectric dimorph comprises a plurality of second piezoelectric dimorphs each in direct conductive electrical contact with the adjacent dimorph and all providing motion in the same planar direction.

6. A piezoelectric actuator capable of providing independently controllable motion in two angularly disposed planes of motion, which comprises:

a first ground electrode layer;

a first piezoelectric wafer, layered onto and in conductive electrical contact with said first ground electrode layer;

a first active electrode, layered onto and in conductive electrical contact with said first piezoelectric wafer;

a second piezoelectric wafer, layered onto and in conductive electrical contact with said first active electrode, and wherein said second piezoelectric wafer is orientated so as to act antiparallel to said first piezoelectric wafer;

second ground electrode, layered onto and in conductive electrical contact with said second piezoelectric wafer;

a third piezoelectric wafer, layered onto and in conductive electrical contact with said second ground electrode, and wherein said third piezoelectric wafer acts angularly with respect to said first and second piezoelectric wafers;

a second active electrode, layered onto and in conductive electrical contact with said third piezoelectric wafer;

a fourth piezoelectric wafer, layered onto and in conductive electrical contact with said second active electrode, and wherein said fourth piezoelectric wafer is oriented so as to act antiparallel to said third piezoelectric wafer;

a third ground electrode, layered onto and in conductive electrical contact with said fourth piezoelectric wafer; and

means for independently controlling the electrical potential applied to said first and second active electrodes.

7. A piezoelectric actuator capable of providing independently controllable motion in first and second angularly disposed planes, comprising:

a first piezoelectric dimorph having first and second piezoelectric wafers positioned adjacent one another, first and second ground electrodes positioned on opposite outer surfaces of said first and second piezoelectric wafers, and a first active electrode extending between said first and second piezoelectric wafers, said first piezoelectric dimorph being oriented so as to produce motion in said first plane in response to an electrical potential applied across said first active electrode and said first and second ground electrodes;

a second piezoelectric dimorph having third and fourth piezoelectric wafers positioned adjacent one another, a third ground electrode positioned on an outer surface of said fourth piezoelectric wafer, and a second active electrode extending between said third and fourth piezoelectric wafers, the outer surface of said third piezoelectric wafer being positioned in direct physical and electrical contact with said second ground electrode of said first piezoelectric dimorph, said second piezoelectric dimorph being oriented so as to produce motion in said second plane in response to an electrical potential applied across said second active electrode and said second and third ground electrodes; and

means for independently controlling an electric field in each of said first and said second piezoelectric dimorphs to produce said independent movement in said first and second piezoelectric dimorphs.

8. A piezoelectric actuator, as set forth in claim 7, wherein said first and second planes are orthogonally disposed.

9. A piezoelectric actuator, as set forth in claim 7, wherein at least one of said first and second piezoelectric dimorphs acts in shear mode.