Actuator
AssigneePhysik Instrumente (Pi) GmbH & Co. KG
InventorsBurhanettin KOC, Bülent DELIBAS
Life of this patent
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Abstract
An actuator with a rectangular shape] is made of polarized electromechanical material having two large main surfaces and at least four side surfaces, two of which being longer than the other two side surfaces. At least one friction element is arranged on at least one of the shorter side surfaces. At least two active electrodes are arranged on one of the main surfaces, with one common electrode arranged on the other of the main surfaces The electromechanical material of the actuator is excitable to perform standing wave deformations due to an electric field generated therein for moving the friction element to drive an element. The actuator aspect ratio for its length to its thickness is between 3.9 and 4.1 and an aspect ratio for the length relative to width is between 2 and 5.
Claims18
An actuator with a rectangular shape comprises:
- polarized electromechanical material having two large main surfaces and four side surfaces connecting the main surfaces with each other, two of said side surfaces representing long side surfaces being longer than the other two side surfaces representing short side surfaces;
- at least one friction element arranged on at least one of the shorter side surfaces, the actuator having a length L, a thickness T and a width W;
- and
- at least two active electrodes arranged on one of the main surfaces, and one common electrode arranged on the other of the main surfaces, with the electrodes arranged on the main surfaces defining outer electrodes, where the electromechanical material of the actuator is polarized in its thickness direction and excitable to perform standing wave deformations due to an electric field generated therein upon application of an electric voltage to the electrodes, said deformations leading to a corresponding movement of the friction element, and said movement of the friction element being usable to drive an element to be driven via friction contact between the friction element and the element to be driven, wherein in an unexcited state of the actuator, an aspect ratio for the length L of the actuator to its thickness T is between 3.9 and 4.1 and an aspect ratio for the length L of the actuator to its width W is between 2 and 5, with said aspect ratios being suitable for excitation of a first standing wave causing a first longitudinal vibration mode in a length direction of the actuator and for excitation of a second standing wave causing a second bending mode in a thickness direction of the actuator, with the second bending mode vibration perturbing the first longitudinal mode resulting in an elliptic trajectory of the movement of the friction element, said elliptic trajectory being usable to drive an element to be driven along the thickness direction of the actuator.
Method for driving an actuator having polarized electromechanical material having two large main surfaces and four side surfaces connecting the main surfaces with each other, two of said side surfaces representing long side surfaces being longer than the other two side surfaces representing short side surfaces;
- at least one friction element arranged on at least one of the shorter side surfaces, the actuator having a length L, a thickness T and a width W;
- and
- at least two active electrodes arranged on one of the main surfaces, and one common electrode arranged on the other of the main surfaces, with the electrodes arranged on the main surfaces defining outer electrodes, where the electromechanical material of the actuator is polarized in its thickness direction and excitable to perform standing wave deformations due to an electric field generated therein upon application of an electric voltage to the electrodes, wherein in an unexcited state of the actuator, an aspect ratio for the length L of the actuator to its thickness T is between 3.9 and 4.1 and an aspect ratio for the length L of the actuator to its width W is between 2 and 5, with said aspect ratios being suitable for excitation of a first standing wave causing a first longitudinal vibration mode in a length direction of the actuator and for excitation of a second standing wave causing a second bending mode in a thickness direction of the actuator, with the second bending mode vibration perturbing the first longitudinal mode resulting in an elliptic trajectory of the movement of the friction element, said elliptic trajectory being usable to drive an element to be driven along the thickness direction of the actuator, the method comprising:
- exciting a first standing wave for causing a first longitudinal vibration mode in the length direction of the actuator;
- and
- exciting a second standing wave for causing a second bending mode in the thickness direction of the actuator, with the second bending mode vibration perturbing the first longitudinal mode resulting in an elliptic trajectory of movement of the friction element, wherein only one of the active electrodes is applied with an electric voltage, while the at least one other active electrode is floating.
Dependencies are inferred from the claim text.