Patent ID: 7792252

Claim:
A multileaf collimator, comprising: a leaf mounted displaceably in an adjusting linear direction that contributes to establish a contour of a beam path; a linear drive assigned to the leaf that displaces the leaf in the adjusting linear direction; a piezoelectric actuator arranged on the linear drive that moves the linear drive, wherein the piezoelectric actuator comprises a piezoelectric element and a transducer coupled thereto; and a control device that drives the piezoelectric actuator in accordance with an asymmetrically-changing voltage, the control device being operable to drive the piezoelectric element with a high speed, wherein essentially no friction is transmitted to the leaf, and being operable to drive the piezoelectric element with a low speed, wherein a frictional force is transmitted to the leaf as a driving force, wherein the asymmetrically-changing voltage is configured so that during a first state of the changing voltage the transducer overcomes a level of static frictional force between the transducer and the leaf, and, in response to overcoming said level of static frictional force, the transducer slides relative to the leaf to travel an interval in a direction opposite to the adjusting direction, wherein the asymmetrically-changing voltage is further configured so that during a second state of the changing voltage the transducer is within the level of static frictional force between the transducer and the leaf, and, in response to being within said level of static frictional force, the transducer is affixed to the leaf by way of said static frictional force to drive the leaf so that the leaf travels the interval in the adjusting direction.