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1. (WO1993019494) MOTEUR PIEZO-ELECTRIQUE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

Claims

1. A method of translating a load using a piezo-electric motor wherein a plurality of piezo-electric actuators are disposed about and held in constant contact with the load by normal forces so that frictional forces hold the load stationary, the method comprising supplying driving voltages to the actuators to:- (a) simultaneously actuate and move all of the
actuators to translate the load without any
sliding between the actuators and the load;
and
(b) actuate all of the actuators in ones or groups at different times to slide them relative to
the load while the remaining actuator or
actuators hold the load stationary.

2. A method as claimed in claim 1 wherein the steps (a) and (b) are repeated to translate the load in a stepwise manner.

3. A method as claimed in claim 1 or 2 wherein step (b) comprises actuating each one or group of the
actuators sequentially to slide them across the load until they have all been moved to new positions, and step (a) is performed before or after this step.

4. A method as claimed in claim 3 , wherein the driving signal supplied to each actuator in step (a) is
identical.

5. A method as claimed in claim 1, 2, 3 or 4 wherein step (a) comprises moving the actuators in" the same direction to move the load in a linear manner.

6. A method as claimed in claim 1, 2, 3 or 4 wherein step (a) comprises moving the actuators along tangents to a circle to rotate the load about the axis of the circle.

7. A method as claimed in any preceding claim, further comprising the step of maintaining a constant driving signal to all of the actuators to cause them to
translate the load within the range of a single-step size.

8. A method as claimed in any preceding claim wherein step (a) further comprises the step of adjusting the driving signal to control the force or torque acting on the load when the actuators move.

9. A method as claimed in claim 8 wherein the driving signal for step (a) is the smooth combination of two parabolic curves of voltage against time.

10. A method as claimed in any preceding claim
comprising (a) applying a rapidly rising actuating signal to a first actuator or group of actuators and holding it, subsequently applying a rapidly rising actuating signal to a second actuator or group of actuators and holding it, continuing to apply and hold actuating signals until all of the actuators have been slid relative to the load, and (b) either before or after step (a) simultaneously reducing the actuating signals to all of the actuators to apply substantially identical driving forces to the load.

11. An apparatus for translating a load comprising: -

(a) a body having a V-shaped groove having a
plurality of piezo-electric actuators disposed on its sloping surfaces, onto which a
triangular cross-sectioned load can be placed;

(b) a plate having a plurality of piezo-electric
actuators disposed on one surface thereof, the plate being placed on top of the load so the
actuators rest thereon;
(c) means for applying a force to the plate to
push it towards the groove, thus applying a normal pressure on the contact surfaces
between the actuators and load; and
(d) control means for supplying driving signals to each of the actuators.

12. An apparatus as claimed in claim 11 wherein the means for applying a force comprise spring means.

13. An apparatus as claimed in claim 12 wherein the spring means comprises bellows attached to the body on each side of the groove and extending across it,

14. An apparatus as claimed in claim 12 or 13 wherein a ball is disposed between the spring means and the plate, so that the plate is under single point loading.