Adaptive registration during precision graphics cutting from multiple sheets

In a method for narrow-path processing graphics areas on a multiplicity of substantially-identical sheets having registration marks at predetermined positions at and about the graphics areas, including (a) providing a plotter for sequentially receiving the sheets, (b) providing a sensor operatively connected to the plotter for moving over a work surface and configured to sense work-surface positions of registration marks of the sheets, (c) providing a narrow-path processing tool operatively connected to the sensor and movable to narrow-path-process the graphics areas on a sheet in response to sensed registration-mark positions with respect to the work surface, and (d) providing a programmed controller operatively connecting the tool to the sensor to control tool movement, the improvement comprising:

• sensing the work-surface positions of the registration marks of a sheet and calculating an expected work-surface position for each registration mark based on the work-surface positions of at least some of the other registration marks;
• classifying each registration mark as active or inactive based on a first error criterion and applying the classification to corresponding marks of a subsequent sheet, the active marks being fewer than the total number of registration marks;
• sensing the work-surface positions of the active registration marks of the subsequent sheet;
• and narrow-path-processing the graphics area(s) on the subsequent sheet based on the sensed positions of the active marks, thereby reducing the time for accurate narrow-path-processing of the subsequent sheet.

In apparatus for cutting graphics areas from a multiplicity of substantially-identical sheets having registration marks at predetermined positions at and about the graphics areas, including (a) a plotter for sequentially receiving the sheets, (b) a sensor operatively connected to the plotter for moving over a work surface and configured to sense work-surface positions of registration marks of the sheets, (c) a cutter operatively connected to the sensor and movable to cut the graphics areas from a sheet in response to sensed registration-mark positions, and (d) a programmed controller operatively connecting the cutter to the sensor to control cutter movement, the apparatus adapted to:

• sense the work-surface positions of the registration marks of a sheet and calculate an expected work-surface position for each of registration mark based on the work-surface positions of at least some of the other registration marks;
• classify each registration mark as active or inactive based on a first error criterion and apply the classification to corresponding marks of a subsequent sheet, the active marks being fewer than the total number of registration marks;
• sense the work-surface positions of the active registration marks of the subsequent sheet;
• and cut the graphics area(s) from the subsequent sheet based on the sensed positions of the active marks, thereby reducing the time for accurate cut-processing of the subsequent sheet.