Method and apparatus for automatic precision cutting of graphics areas from sheets

• US 20030047045A1
• Filed: 09/13/2001
• Published: 03/13/2003
• Est. Priority Date: 04/05/2001
• Status: Active Grant

• Current Assignee: Esko Graphics Kongsberg AS
• Original Assignee: Mikkelsen Graphic Engineering Incorporated
• Inventors: Andersen, Geo, Alsten, Peter
• Granted Patent: US 6,619,168 B2
• Time in Patent Office: Days
• US Class Current: 83/13
• CPC Class Codes: B26D 5/00 Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
• CPC Class Codes: B26D 5/005 Computer numerical control means
• CPC Class Codes: B26D 5/34 scanning being effected by a photosensitive device
• CPC Class Codes: B26F 1/3813 wherein the tool head is moved in a plane parallel to the work in a coordinate system fixed with respect to the work
• CPC Class Codes: Y10S 83/94 Cutter moves along bar, bar moves perpendicularly
• CPC Class Codes: Y10T 83/04 Processes
• CPC Class Codes: Y10T 83/0524 Plural cutting steps
• CPC Class Codes: Y10T 83/0586 Effecting diverse or sequential cuts in same cutting step
• CPC Class Codes: Y10T 83/155 Optimizing product from unique workpiece
• CPC Class Codes: Y10T 83/178 Responsive to work
• CPC Class Codes: Y10T 83/531 With plural work-sensing means
• CPC Class Codes: Y10T 83/533 With photo-electric work-sensing means
• CPC Class Codes: Y10T 83/538 Positioning of tool controlled
• CPC Class Codes: Y10T 83/543 Sensing means responsive to work indicium or irregularity

Abstract

An improved method and apparatus for automatic cutting of graphics area(s) from a sheet of material which includes such graphics area(s), the graphics areas having a plurality of registration marks in predetermined positions with respect thereto and including a subset of the marks on no more than one side of the graphics area which are initial-position/orientation-determining marks. The method involves placing the sheet on a sheet-receiving surface, attempting to sense the subset in the field of view of a main sensor, and, when the subset is not in an expected location, automatically determining the coordinate region of the subset on the sheet-receiving surface and automatically repositioning the main sensor to the coordinate region such that the subset is within the field of view of the main sensor. Then the position and orientation of the sheet and approximate positions of the plurality of marks are determined based on sensing the subset, and thereafter their precise positions are sensed to guide cutting operations.

Claims

1. In a method for cutting a graphics area from a sheet of material bearing such graphics area and a plurality of registration marks in predetermined positions with respect thereto, a subset of the marks being initial-position/orientation-determining marks on no more than one side of the graphics area, the method being of the type including (a) placing the sheet on a sheet-receiving surface, (b) sensing the subset in the field of view of a main sensor to determine the position and orientation of the sheet and approximate positions of the plurality of marks, (c) sensing the precise positions of the marks, and (d) cutting the graphics area from the sheet in response to the precise positions of the marks with respect to the graphics area, the improvement comprising:

if the subset is not in an expected location, automatically determining the coordinate region of the subset on the sheet-receiving surface; and

in response to the determining step, automatically repositioning the main sensor to the coordinate region such that the subset is within the field of view of the main sensor.

2. The method of claim 1 wherein:

the automatic determining step includes enlarging the field of view of the main sensor and locating the coordinate region of the subset within the enlarged field of view; and

the automatic repositioning includes shrinking the field of view of the main sensor such that the subset is within the field of view of the main sensor.

3. The method of claim 2 wherein enlarging and shrinking the field of view of the main sensor includes zooming a lens of the main sensor.

4. The method of claim 2 wherein:

the enlarging step includes increasing the distance between the main sensor and the sheet of material; and

the shrinking step includes decreasing the distance between the main sensor and the sheet of material.

5. The method of claim 1 wherein the automatic determining step includes locating the coordinate region of the subset within the field of view of a secondary sensor.

6. The method of claim 1 wherein automatically determining the coordinate region of the subset includes sensing directive indicia on the sheet of material which indicate the coordinate region of the subset, the directive indicia being outside the coordinate region of the subset.

7. The method of claim 1 wherein automatically determining the coordinate region of the subset includes:

moving the main sensor in a predetermined pattern surrounding the expected location of the subset; and

stopping the movement of the main sensor when the coordinate region of the subset is located within the field of view of the main sensor.

8. The method of claim 7 wherein the moving step includes rotating the main sensor such that the field of view changes.

9. The method of claim 1 wherein:

the automatic determining step includes determining (a) the direction from the expected location to the actual location and (b) the distance between the expected location and the actual location; and

the repositioning step is movement in the determined direction for the determined distance.

10. In a method for cutting a graphics area from a sheet of material bearing such graphics area and a plurality of registration marks in predetermined positions with respect thereto at the time the graphics are applied, a subset of the marks being initial-position/orientation-determining marks on no more than one side of the graphics area, the method being of the type including (a) placing the sheet on a sheet-receiving surface, (b) sensing the subset in the field of view of a main sensor to determine the position and orientation of the sheet and approximate positions of the plurality of marks at the time of cutting, (c) sensing the precise positions of the marks, and (d) cutting the graphics area from the sheet in response to the precise positions of the marks with respect to the graphics area at that time, the improvement comprising:

if the subset is not in an expected location, automatically determining the coordinate region of the subset on the sheet-receiving surface; and

in response to the determining step, automatically repositioning the main sensor to the coordinate region such that the subset is within the field of view of the main sensor

whereby cutting occurs precisely despite two-dimensional distortion of the sheet prior to cutting.

11. In a method for narrow-path-processing with respect to a graphics area on a sheet of material bearing such graphics area and a plurality of registration marks in predetermined positions with respect thereto, a subset of the marks being initial-position/orientation-determining marks on no more than one side of the graphics area, the method being of the type including (a) placing the sheet on a sheet-receiving surface, (b) sensing the subset in the field of view of a main sensor to determine the position and orientation of the sheet and approximate positions of the plurality of marks, (c) sensing the precise positions of the marks, and (d) narrow-path-processing with respect to the graphics area on the sheet in response to the precise positions of the marks with respect to the graphics area, the improvement comprising:

if the subset is not in an expected location, automatically determining the coordinate region of the subset on the sheet-receiving surface; and

in response to the determining step, automatically repositioning the main sensor to the coordinate region such that the subset is within the field of view of the main sensor.

12. In apparatus for cutting a graphics area from a sheet of material bearing such graphics area and a plurality of registration marks in predetermined positions with respect thereto, a subset of the marks being initial-position/orientation-determining marks on no more than one side of the graphics area, the apparatus being of the type including (a) a sheet-receiving surface, (b) a main sensor for sensing the subset in the field of view of the main sensor to determine the position and orientation of the sheet and approximate positions of the plurality of marks and for sensing the precise positions of the marks, and (c) a cutter operatively connected to the sensor and movable about the sheet-receiving surface, the cutter cutting the graphics area from the sheet of material in response to the precise positions of the marks sensed by the main sensor, the improvement comprising a coordinate region locator which, if the subset is not in an expected location, automatically determines the coordinate region of the subset on the sheet-receiving surface and in response thereto automatically repositions the main sensor to the coordinate region such that the subset is within the field of view of the main sensor.

13. The apparatus of claim 12 wherein the coordinate region locator includes:

a zoom lens on the main sensor; and

a controller with a set of locating instructions for (a) enlarging the field of view of the main sensor by zooming the lens, (b) locating the coordinate region of the subset within the enlarged field of view, (c) repositioning the main sensor in response to the locating step, and (d) shrinking the field of view of the main sensor by zooming the lens such that the subset is within the field of view of the main sensor.

14. The apparatus of claim 12 wherein the coordinate region locator includes:

a main-sensor height adjustor; and

a controller with a set of locating instructions for (a) enlarging the field of view of the main sensor by increasing the distance of the main sensor from the sheet material, (b) locating the coordinate region of the subset within the enlarged field of view, (c) repositioning the main sensor in response to the locating step, and (d) shrinking the field of view of the main sensor by decreasing the distance of the main sensor from the sheet such that the subset is within the field of view of the main sensor.

15. The apparatus of claim 12 wherein the coordinate region locator includes:

a secondary sensor with a field of view larger than the field of view of the main sensor; and

a controller with a set of locating instructions for (a) locating the coordinate region of the subset within the field of view of the secondary sensor, and (b) repositioning the main sensor in response to the locating step such that the subset is within the field of view of the main sensor.

16. The apparatus of claim 12 wherein the coordinate region locator includes;

directive indicia printed on the sheet of material outside the coordinate region of the subset in predetermined positions and orientations with respect to the subset; and

a controller with a set of locating instructions for (a) determining the coordinate region of the subset by sensing the directive indicia, and (b) repositioning the main sensor in response thereto, such that the subset is within the field of view of the main sensor.

17. The apparatus of claim 12 wherein the coordinate region locator includes a controller with a set of locating instructions for (a) moving the main sensor in a predetermined pattern surrounding the expected location of the subset, and (b) stopping the movement of the main sensor when the coordinate region of the subset is located within the field of view of the main sensor.