Method for reciprocating a workpiece through an ion beam
View Patent ↗A method for reciprocally transporting a workpiece on a scan arm through an ion beam is provided, wherein the scan arm is operably coupled to a motor comprising a rotor and stator that are individually rotatable about a first axis. An electromagnetic force applied between the rotor and stator rotates the rotor about the first axis and translates the workpiece through the ion beam along a first scan path. A position of the workpiece is sensed and the electromagnetic force between the rotor and stator is controlled in order to reverse the direction of motion of the workpiece along the first scan path, and wherein the control is based, at least in part, on the sensed position of the workpiece. The stator further rotates about the first axis in reaction to the rotation of the rotor, particularly in the reversal of direction of motion of the workpiece, thus acting as a reaction mass to the rotation of one or more of the rotor, scan arm, and workpiece.
1. A method for reciprocally transporting a workpiece, the method comprising the steps of:
providing the workpiece on a scan arm, wherein the scan arm is operably coupled to a motor comprising a rotor and a stator, and wherein the rotor and stator are operable to individually rotate and counter-rotate about a first axis;
generating an electromagnetic force between said rotor and said stator so as to induce rotation of said rotor, wherein the rotation of said rotor further induces rotation of said stator, and further wherein rotation of said rotor translates said scan arm such that the workpiece travels through the ion beam along a first scan path; and
controlling the electromagnetic force generated between said rotor and said stator to selectively reverse the rotation of said rotor and thereby reciprocally transport the workpiece along the first scan path, wherein said stator rotates and counter-rotates about the first axis in reaction to the reciprocating transport of the workpiece.
2. The method of claim 1 , wherein a mass moment of inertia associated with said stator is greater than or equal to a total of mass moments of inertia of said scan arm and the workpiece.
3. The method of claim 2 wherein said stator comprises an inertial mass coupled thereto, wherein the mass moment of inertia thereof is greater than or equal to the total mass moments of inertia of said scan arm and workpiece.
4. The method of claim 1 , further including the step of sensing a position of the workpiece along the first scan path for controlling the electromagnetic force, wherein said sensing of the position of the workpiece comprises sensing a rotational position of one or more of the shaft, rotor, and stator about the first axis, wherein the control of the electromagnetic force is based, at least in part, on the sensed rotational position of the respective shaft, rotor, and stator about the first axis.
5. The method of claim 4 , wherein sensing the rotational position of one or more of the shaft, rotor, and stator about the first axis comprises:
sensing a first rotational orientation of the rotor with respect to the stator; and
sensing a second rotational orientation of the rotor with respect to a generally stationary reference, wherein the control of the electromagnetic force is based, at least in part, on the first rotational orientation of the rotor with respect to the stator and second rotational position of the rotor with respect to the generally stationary reference.
6. The method of claim 5 , comprising repeatedly sensing the rotational position of one or more of the shaft, rotor, and stator throughout the reciprocating transport of the workpiece.
7. The method of claim 5 , wherein the step of controlling the electromagnetic force is further based on a set of predetermined criteria.
8. The method of claim 7 , wherein the set of predetermined criteria comprises one or more of a number of reciprocations of the workpiece along the first scan path, a desired velocity of the workpiece at one or more predetermined positions of the workpiece along the first scan path, and a desired acceleration of the workpiece at the one or more predetermined positions of the workpiece along the first scan path.
9. The method of claim 8 , wherein the one or more predetermined positions of the workpiece are associated with one or more of a predetermined beam impact range and a turn-around range, wherein the beam impact range is generally defined by positions of the workpiece along the first scan path in which the ion beam impinges upon the workpiece, and wherein the turn-around range is generally defined by positions of the workpiece along the first scan path in which the ion beam does not impinge upon the workpiece.
10. The method of claim 9 , comprising controlling the electromagnetic force between the rotor and the stator such that the desired velocity of the workpiece is substantially constant within the beam impact range.
11. The method of claim 5 , further comprising the step of rotating the workpiece with respect to the scan arm about a second axis, wherein a rotational orientation of the workpiece about the second axis is generally fixed with respect to the stationary reference, and wherein the rotation of the workpiece about the second axis is based on the sensed second rotational orientation of the rotor with respect to the stationary reference.
12. The method of claim 1 , further comprising translating the motor along a third axis generally perpendicular to the first axis, thereby translating the workpiece along a second scan path generally orthogonal to the first scan path.
13. The method of claim 12 , comprising translating the motor along the third axis at a constant velocity.
14. The method of claim 12 , comprising translating the motor along the third axis when the ion beam does not impinge upon the workpiece.
15. The method of claim 1 , further comprising measuring one or more properties of the ion beam when the ion beam does not impinge upon the workpiece.
16. A method for reciprocating a workpiece through an ion beam, the method comprising:
providing the workpiece on a scan arm, wherein the scan arm is operably coupled to a motor comprising a rotor and a stator, and wherein the rotor and stator are operable to individually rotate and counter-rotate about a first axis; and
applying an electromagnetic force between the rotor and stator, therein translating the workpiece through the ion beam along a first scan path.
17. The method of claim 16 , further comprising:
sensing a position of the workpiece; and
controlling the electromagnetic force between the rotor and stator to reciprocate the workpiece along the first scan path, wherein the control is based, at least in part, on the sensed position of the workpiece, and wherein the stator rotates and counter-rotates about the first axis in reaction to the reciprocation of the workpiece.
18. A method for reciprocating a workpiece through a process medium, the method comprising:
rotating a rotor of a motor about a first axis, therein translating the workpiece along a first scan path; and
rotating a stator of the motor about the first axis in reaction to the rotation of the rotor.
19. The method of claim 18 , further comprising:
sensing a rotational position of the rotor and the stator; and
controlling the rotation of the rotor, wherein the control is based, at least in part, on the sensed rotational position of the rotor and the stator.
20. The method of claim 18 , further comprising translating the workpiece along a second scan path, wherein the second scan path is generally perpendicular to at least a portion of the first scan path.