COMPUTER CONTROLLED WORK TOOL APPARATUS AND METHOD

• US 20110190922A1
• Filed: 08/26/2008
• Published: 08/04/2011
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: Zeeko Limited
• Original Assignee: Zeeko Limited
• Inventors: Walker, David, Beaucamp, Anthony, Dunn, Christina
• Granted Patent: US 9,952,585 B2
• Time in Patent Office: Days
• US Class Current: 700/118
• CPC Class Codes: B24B 13/06 grinding of lenses, the tool or work being controlled by information-carrying means, e.g. patterns, punched tapes, magnetic tapes
• CPC Class Codes: B24D 13/142 Wheels of special form
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 19/4103 Digital interpolation
• CPC Class Codes: G05B 2219/34105 Area pocket machining, space filling curve, to cover whole surface
• CPC Class Codes: G05B 2219/34118 Using a pseudo-random or random tool path
• CPC Class Codes: G05B 2219/34141 B-spline, NURBS non uniform rational b-spline
• CPC Class Codes: G05B 2219/35122 Generate random paths along a raster path
• CPC Class Codes: G05B 2219/45157 Grind optical lens
• CPC Class Codes: G05B 2219/45199 Polish
• CPC Class Codes: G05B 2219/45232 CMP chemical mechanical polishing of wafer
• CPC Class Codes: G05B 2219/49352 7-Axis surface machining

Abstract

A polishing machine is described in which a surface treatment tool is moved across the surface of a workpiece in accordance with a predefined tool-path, in order to carry out the desired treatment process. The tool-path is non-periodic and preferably pseudo-random. Various techniques are described for generating data representing the tool-path to be followed. A technique is also described for determining optimum control parameters used to control the polishing machine for a given tool-path. The surface treatment may be a shaping technique in which material is removed from the surface, or a technique for adding material to the surface of the workpiece, or a technique for modifying the surface or a region under the surface of the workpiece.

Claims

1. A tool-path generator comprising:

a memory operable to store surface model data defining a three-dimensional (3D) surface area of a workpiece to be worked;

a rules database comprising a plurality of rules relating to tool-path generation; and

a tool-path determiner operable to determine data representing a pseudo-random tool-path along the 3D surface of the workpiece area to be worked in accordance with rules from said rules database.

2. A tool-path generator according to claim 1, wherein said surface model data defines said surface area in a two-dimensional (2D) projection and wherein said tool-path determiner is operable to determine data representing a 2D path within said 2D projection and is operable to project the data representing said 2D path into 3D to define said data representing said pseudo-random tool-path.

3. A tool-path generator according to claim 1, wherein said surface model data is operable to define said surface using two-dimensional parametric polynomials, wherein said tool-path determiner is operable to determine data representing a 2D path within a 2D space of said parametric polynomials and is operable to use said parametric polynomials to convert said data representing said 2D path into said data representing said pseudo-random tool-path.

4. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine said data representing said 2D path using one or more predetermined stippling patterns.

5. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine said data representative of said 2D path using adaptive isocurves in accordance with rules in said rules database.

6. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine said data representative of said 2D path using a random walk algorithm in accordance with rules in said rules database.

7. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine said data representative of said 2D path using an artificial ant algorithm in accordance with rules in said rules database.

8. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine said data representative of said 2D path on the basis of a maze algorithm in accordance with rules in said rules database.

9. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine said data representative of said 2D path using a genetic algorithm in accordance with rules in said rules database.

10. A tool-path generator according to claim 3, wherein said data representative of said 2D path comprises a sequence of 2D points and wherein the tool-path determiner is operable to determine said data representing said pseudo-random tool-path by converting said sequence of 2D points into 3D points using said parametric polynomials.

11. A tool-path generator according to claim 10, wherein said tool-path determiner is operable to determine lines and/or curves between successive 3D points obtained from said parametric polynomials to determine said data representing said pseudo-ransom tool-path.

12. A tool-path generator according to claim 10, wherein said tool-path determiner is operable to fit a curve to said 3D points in order to determine said data representing said pseudo-random tool-path.

13. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine a sequence of points within said 2D space, which 2D points identify control points for a plurality of spline segments that define said 2D path.

14. A tool-path generator according to claim 13, wherein said surface model data represents said surface using two-dimensional non-uniform rational B-splines and wherein said control points are control points for a non-uniform rational B-spline.

15. A tool-path generator according to claim 3, wherein said data representative of said 2D path comprises 2D coordinate positions for a sequence of points randomly positioned within said 2D space.

16. A tool-path generator according to claim 3, wherein said tool-path determiner is operable to determine data representing said 2D path comprising a sequence of points positioned in said 2D space in accordance with a distribution function defined by rules in said rules database.

17. A tool-path generator according to claim 16, wherein said rules define a weighted distribution function which causes said tool-path determiner to determine more 2D points at positions in said 2D space corresponding to boundaries of said workpiece.

18. A tool-path generator according to claim 3, wherein said surface model data includes data identifying an amount of work to be carried out on different parts of said surface and wherein said tool-path determiner is operable to determine data representing said 2D path comprising a sequence of points distributed within said 2D space in dependence upon the amount of work to be carried out in the different parts of the surface.

19. A tool-path generator according to claim 2, wherein said tool-path determiner is operable to determine data representative of a 2D path which does not cross itself within said 2D space.

20. A tool-path generator according to claim 2, wherein said tool-path determiner is operable to determine data representing said 2D path using a uniformly-spaced lattice of points within said 2D space.

21. A tool-path generator according to claim 2, wherein said tool-path determiner is operable to define said data representative of said 2D path using a lattice of points in which the spacing between lattice points depends on an amount of work to be performed in a corresponding portion of said surface.

22. A tool-path generator according to claim 2, wherein said tool-path determiner is operable to determine data representing a plurality of 2D paths and wherein said tool-path definer is operable to select one or more of said 2D paths in accordance with a predetermined selection process.

23. A tool-path generator according to claim 22, wherein said tool-path determiner is operable to select said one or more 2D paths using artificial intelligence techniques in accordance with rules in said rules database.

24. A tool-path generator according to claim 22, wherein said tool-path determiner is operable to evaluate estimated effects of a tool working said surface along tool-paths corresponding to each possible 2D path and operable to select one or more of said 2D paths that result, on their own or in combination, in a desired working of the surface by said tool.

25. A tool-path generator according to claim 1, wherein said tool-path determiner is operable to determine data representing said tool-path which comprises 3D coordinates of a sequence of points along said tool-path.

26. A tool-path generator according to claim 25, wherein said tool-path determiner is operable to determine lines and/or curves between successive points within said sequence of points in order determine said data representing said tool-path.

27. A tool-path generator according to claim 25, wherein said tool-path determiner is operable to fit a curve to said sequence of points in order to determine said data representative of said pseudo-random tool-path.

28. A tool-path generator according to claim 1, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path which does not cross itself.

29. A tool-path generator according to claim 1, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path in which the transverse distance between neighbouring stretches of the path is arranged to be within a predetermined range of distances.

30. A tool-path generator according to claim 1, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path in which the transverse distance between neighbouring stretches of the path is substantially the same for all or substantially all points on the path.

31. A tool-path generator according to claim 1, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path in which the transverse distance between neighbouring stretches of the path is different at different points along the path.

32. A tool-path generator according to claim 31, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path in which the transverse distance between neighbouring stretches of the path is reduced for points on the path which lie adjacent the edge of the area.

58. An apparatus according to claim 56, wherein the controller is operable to control relative movement between the support and the tool to cause the tool to follow a pseudo-random tool-path across said surface of the workpiece, which tool-path is generated using an apparatus according to any of claims 1 to 32.

61. An apparatus according to claim 60, wherein said tool-path is defined using a tool-path generator according to claim 1.

70. A method of generating a tool-path characterised by the use of a tool-path generator according to claim 1.

73. A computer implementable instructions product comprising computer implementable instructions to cause a programmable computer device to become configured as a tool-path generator according to claim 1.

33. An apparatus for performing a surface treatment on an area, by moving a surface treatment device having a treatment footprint along an irregular path such that the footprint of the treatment tool passes over all points of the area.

34. An apparatus according to claim 33, wherein the path is a random or pseudo-random path.

35. An apparatus according to claim 33, wherein the path visits all points of the area without visiting any point twice.

36. An apparatus according to claim 35, wherein the transverse distance between neighbouring stretches of the path is arranged to be within a predetermined range of distances.

37. An apparatus according to claim 35, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is substantially the same for all or substantially all points on the path.

38. An apparatus according to claim 34, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is different at different points along the path.

39. An apparatus according to claim 38, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is reduced for points on the path which lie adjacent the edge of the area.

40. A method for performing a surface treatment on an area, by moving a surface treatment device having a treatment footprint over the area;

the method comprising;

generating an irregular path which visits all points of the area; and

moving the surface treatment device along the irregular path such that the footprint of the treatment tool passes over all points of the area.

41. A method according to claim 40, wherein the path is a random or pseudo-random path.

42. A method according to claim 41, wherein the path visits all points of the area without visiting any point twice.

43. A method according to claim 42, wherein the transverse distance between neighbouring stretches of the path is arranged to be within a predetermined range of distances.

44. A method according to claim 42, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is substantially the same for all or substantially all points on the path.

45. A method according to claim 40, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is different at different points along the path.

46. A method according to claim 45, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is reduced for points on the path which lie adjacent the edge of the area.

77. A workpiece comprising a surface which has been shaped or treated using a method according to claim 40.

78. A semiconductor device fabricated from a wafer which has been shaped or treated using a method according to claim 40.

79. A display device including a component which has been shaped or treated using a method according to claim 40.

47. A computer-controlled tool for working on or under the surface of a workpiece by moving a surface treatment tool along a predefined tool-path which is non-periodic.

48. A tool according to claim 47, wherein the tool-path is substantially random (pseudo-random) and generated using, for example, an artificial ant algorithm.

49. A tool according to claim 47, wherein the tool-path does not cross itself.

50. A tool according to claim 47, wherein the tool-path is arranged so that, from a tool-path point which is within a first predetermined distance of the workpiece boundary, the tool-path may not proceed in a direction within a predetermined angular range from the normal joining the workpiece boundary to that tool-path point.

51. A tool according to claim 47, wherein the tool-path is arranged so that, from a tool-path point on the workpiece boundary, the tool-path may only proceed in a direction away from the boundary and within a predetermined angular range from the normal to the workpiece boundary.

52. A tool according to claim 47, wherein the transverse distance between neighbouring stretches of the tool-path is arranged to be within a predetermined range of distances.

53. A tool according to claim 47, wherein the tool-path is arranged so that the transverse distance between neighbouring stretches of the tool-path is substantially the same for all or substantially all points on the tool-path.

54. A tool according to claim 47, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is different at different points along the path.

55. A tool according to claim 54, wherein the path is arranged so that the transverse distance between neighbouring stretches of the path is reduced for points on the path which lie adjacent the edge of the area.

56. An apparatus for treating the surface of a workpiece, the apparatus comprising:

a support operable to support the workpiece;

a tool operable to perform an action on or under said surface of the workpiece to treat said surface; and

a controller operable to control relative movement between the support and the tool, to cause the tool to follow a non-periodic tool-path across said surface of the workpiece to perform said treatment of the surface.

57. A machine according to claim 56, wherein said treatment comprises one or more of:

the removal of material from the surface of said workpiece, the addition of material to the surface of said workpiece, and the modification of the surface or an area under the surface of said workpiece.

59. An apparatus according to claim 56, wherein the treatment comprises abrading or polishing the workpiece.

60. An apparatus for working a workpiece, the apparatus comprising:

a support operable to support the workpiece to be worked;

a tool operable to effect a time-dependent cumulative action on or under a surface of the workpiece within a region that is smaller than said surface and which is located adjacent said tool; and

a controller operable to control relative movement between the support and the tool to cause the tool to follow a non-periodic tool-path across said surface of the workpiece to effect said time-dependent cumulative action on or under said surface within regions of the workpiece corresponding to said tool-path.

62. An apparatus according to claim 60, wherein said controller is operable to control the values of one or more controllable parameters of the apparatus to control the treatment of the workpiece along said tool-path, to cause the apparatus to vary the treatment of said surface at different locations along said tool-path.

63. An apparatus according to claim 60, wherein said controller comprises an optimiser operable to optimise control parameters used to control the working of the workpiece along said tool-path.

64. A machine for polishing or abrading a surface of a workpiece, the machine comprising:

a support operable to support the workpiece to be polished or abraded;

a tool operable to effect a time-dependent polishing or abrading action on the surface of said workpiece within a region that is smaller than said surface and which is located adjacent said tool; and

a controller operable to control relative movement between the support and the tool to cause the tool to follow a non-periodic tool-path across said surface of the workpiece to effect said polishing and/or abrading action within regions of the workpiece corresponding to said tool-path.

65. A machine according to claim 64, wherein said controller is operable to control said tool and said relative movement in order to vary the polishing or abrading action on said surface along said tool-path so that different regions of said surface receive different amounts of polishing and/or abrading.

66. A machine according to claim 64, wherein said controller is operable to use an optimisation process to determine optimal control parameters for controlling the polishing or abrading action performed by said tool along said tool-path, using data defining an influence function of the tool, the influence function defining the pattern of removal of material from the workpiece for a predetermined dwell time or speed of the tool and based on data defining a desired profile and a current profile of the surface of the workpiece.

67. A machine according to claim 66, wherein said controller is operable to determine dwell times or tool speeds for predetermined positions on said surface of the workpiece to provide a predicted removal profile and is operable to vary the dwell times or tool speeds and other controllable parameters of the tool using a numerical optimisation process to determine control parameters and dwell times or tool speeds along said tool path that will minimise an estimated error between said desired profile and the profile of the surface after said tool has performed said polishing or abrading along said tool-path.

68. A machine according to claim 64, wherein said controller is operable to control relative movement between the support and the tool to cause the tool to follow a pseudo-random tool-path across said surface of the workpiece to effect said polishing and/or abrading action within regions of the workpiece corresponding to said tool-path.

69. A method of generating a tool-path comprising:

holding surface model data defining a three-dimensional (3D) surface of a workpiece to be worked;

providing a rules database comprising a plurality of rules relating to tool-path generation; and

determining data representing a pseudo-random tool-path along the 3D surface of the workpiece to be worked in accordance with rules from said rules database.

71. A method of abrading or polishing a workpiece comprising:

supporting the workpiece on a support;

providing a tool for polishing or abrading the surface of the workpiece; and

controlling relative movement between the support and the tool to cause the tool to follow a non-periodic tool-path across the surface of the workpiece to effect said polishing or abrading.

72. A method of finishing the surface of a workpiece, the method comprising:

supporting the workpiece on a support;

providing a tool to perform an action on or under the surface of the workpiece to finish said surface, and

controlling the relative movement between the support and the tool, to cause the tool to follow a non-periodic tool-path across said surface of the workpiece to perform said finishing of the surface.

74. A tool-path generator comprising:

a memory operable to store surface model data defining a three-dimensional (3D) surface of a workpiece to be worked;

a rules database comprising a plurality of rules relating to tool-path generation; and

a tool-path determiner operable to determine data representing a non-periodic tool-path which passes over substantially the whole of said surface of the workpiece, in accordance with rules from said rules database.

75. A tool-path generator according to claim 74, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path over said 3D surface of said workpiece.

76. A tool-path generator according to claim 75, wherein said tool-path determiner is operable to determine data representing a pseudo-random tool-path over a surface on the basis of a maze generated to fit to said surface.