U.S. patent application number 11/416959 was filed with the patent office on 2006-09-07 for method for preparing graphics on sheets.
Invention is credited to Peter Alsten, Geo Andersen, David G. Jansson, Steen Mikkelsen.
Application Number | 20060196381 11/416959 |
Document ID | / |
Family ID | 32174663 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196381 |
Kind Code |
A1 |
Mikkelsen; Steen ; et
al. |
September 7, 2006 |
Method for preparing graphics on sheets
Abstract
A method for preparing a graphic on a sheet (40) of material
which also includes at least one registration mark (44) at and
about the graphic in predetermined positions. The method involves
the steps of applying the graphic (42a, 42b) and at least one
registration mark on a sheet of material in positions according to
layout data, transferring the layout data to a processing
controller, placing the sheet of material on a sheet-receiving
surface (16), sensing the position of the registration mark on the
sheet of material, and utilizing the layout data and the position
of the registration mark to precisely narrow-path-process around
the graphic on the sheet of material. Certain embodiments use
either (a) a subset (46) of marks which is applied on one side of
the graphic or (b) certain reference features, such as edges and
corners of the sheet and elements of the graphic, to ascertain the
position and orientation of the sheet on the apparatus. The
invention provides efficient, rapid, automated, and precise
processing around the graphic.
Inventors: |
Mikkelsen; Steen; (Delavan,
WI) ; Alsten; Peter; (Racine, WI) ; Andersen;
Geo; (Aabyhoej, DK) ; Jansson; David G.;
(Racine, WI) |
Correspondence
Address: |
JANSSON, SHUPE, MUNGER & ANTARAMIAN, LTD
245 MAIN STREET
RACINE
WI
53403
US
|
Family ID: |
32174663 |
Appl. No.: |
11/416959 |
Filed: |
May 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10283460 |
Oct 30, 2002 |
7040204 |
|
|
11416959 |
May 3, 2006 |
|
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|
Current U.S.
Class: |
101/485 |
Current CPC
Class: |
B26D 5/06 20130101; Y10T
83/04 20150401; B26D 5/005 20130101; Y10T 83/05 20150401; Y10T
83/538 20150401; Y10T 83/543 20150401; B26D 5/34 20130101; Y10T
83/152 20150401; B26D 5/00 20130101; Y10T 83/533 20150401; B26D
7/27 20130101; B26F 1/3813 20130101; Y10T 83/0524 20150401; Y10T
83/178 20150401 |
Class at
Publication: |
101/485 |
International
Class: |
B41F 1/34 20060101
B41F001/34 |
Claims
1. A method for automatically preparing at least one graphic on a
sheet of material, the method comprising: non-removably applying to
the sheet of material the graphic and at least one registration
mark in positions according to layout data; transferring the layout
data to a processing controller; placing the sheet of material on a
sheet-receiving surface; automatically sensing the position(s) of
the registration mark(s) on the sheet of material; and utilizing
the layout data and the position(s) of the registration mark(s) to
precisely narrow-path-process around the graphic on the sheet of
material.
2. The method of claim 1 wherein the at least one registration mark
is multiple lines applied to the sheet of material along an edge
thereof.
3. The method of claim 1 wherein the at least one registration mark
is multiple marks applied to the sheet of material along an edge
thereof.
4. The method of claim 1 wherein the at least one registration mark
is multiple marks applied to the sheet of material surrounding the
graphic.
5. The method of claim 1 wherein the at least registration mark
includes a bar code, the method further including the steps of:
reading the bar code to identify the sheet of material on the
sheet-receiving surface; and finding the layout data corresponding
to the graphic and the at least one registration mark.
6. The method of claim 1 wherein the layout data is transferred to
the processing controller through a network connection.
7. The method of claim 1 wherein the layout data is transferred to
the processing controller by downloading the layout data to a disc
and uploading the layout data from the disc to the processing
controller.
8. The method of claim 1 wherein the layout data comprises graphic
data and registration mark data and the transferring step
comprises: transferring the graphic data and registration mark data
to at least one file; transferring the at least one file to the
processing controller; and uploading the graphic data and
registration mark data from the file to the processing
controller.
9. The method of claim 8 wherein the registration mark data
comprises data pertaining to X-Y position, angle orientation and
scale factor.
10. The method of claim 1 wherein the applying step includes
providing at least one registration mark within the graphic.
11. The method of claim 1 wherein the applying step includes
providing at least one registration mark at a known position
relative to the graphic.
12. A method for automatically preparing at least one graphic on a
sheet of material, the method comprising: printing on the sheet of
material the graphic and at least one registration mark in
positions according to layout data; transferring the layout data to
a processing controller; placing the sheet of material on a
sheet-receiving surface; automatically sensing the position(s) of
the registration mark(s) on the sheet of material; and utilizing
the layout data and the position(s) of the registration mark(s) to
precisely narrow-path-process around the graphic on the sheet of
material.
13. The method of claim 12 wherein the at least one registration
mark is multiple lines printed on the sheet of material along an
edge thereof.
14. The method of claim 12 wherein the at least one registration
mark is multiple marks printed on the sheet of material along an
edge thereof.
15. The method of claim 12 wherein the at least one registration
mark is multiple marks printed on the sheet of material surrounding
the graphic.
16. The method of claim 12 wherein the at least registration mark
includes a bar code, the method further including the steps of:
reading the bar code to identify the sheet of material on the
sheet-receiving surface; and finding the layout data corresponding
to the graphic and the at least one registration mark.
17. The method of claim 12 wherein the layout data is transferred
to the processing controller through a network connection.
18. The method of claim 12 wherein the layout data is transferred
to the processing controller by downloading the layout data to a
disc and uploading the layout data from the disc to the processing
controller.
19. The method of claim 12 wherein the layout data comprises
graphic data and registration mark data and the transferring step
comprises: transferring the graphic data and registration mark data
to at least one file; transferring the at least one file to the
processing controller; and uploading the graphic data and
registration mark data from the file to the processing
controller.
20. The method of claim 19 wherein the registration mark data
comprises data pertaining to X-Y position, angle orientation and
scale factor.
21. The method of claim 12 wherein the printing step includes
providing at least one registration mark within the graphic.
22. The method of claim 12 wherein the printing step includes
providing at least one registration mark at a known position
relative to the graphic.
23. In a method for preparing a graphic on a sheet of material, the
method being of the type including the steps of non-removably
applying to the sheet of material the graphic and at least one
registration mark, placing the sheet on a sheet-receiving surface,
sensing positions of the registration marks and utilizing the
positions of the registration marks to narrow-path-process around
the graphic on the sheet of material, the improvement wherein a
processing controller utilizes processing data to
narrow-path-process around the graphic on the sheet of material and
the method comprises: creating and using layout data to apply the
graphic and registration marks to the sheet of material;
transferring the layout data to the processing controller;
identifying the sheet placed on the sheet-receiving surface;
locating the layout data which pertains to the identified sheet;
and utilizing the layout data as the processing data.
Description
RELATED APPLICATION
[0001] This is a continuation of patent application Ser. No.
10/283,460, filed Oct. 30, 2002, issuing on May 9, 2006 as Patent
No. 7,040,204, the contents of which are incorporated herein.
FIELD OF THE INVENTION
[0002] This invention is related generally to the field of cutting
of graphics or the like from sheets for various purposes, and other
narrow-path-processing about graphics on sheets.
BACKGROUND OF THE INVENTION
[0003] The technical field involving the cutting of graphic areas
from sheets, or otherwise doing narrow-path-processing about
graphics images on sheets, includes, for example, the face-cutting
of laminate sheets to form decals. More specifically, a graphic on
the face layer of a laminate needs to be cut away from the
remainder of the face layer so that the graphic (decal) can
subsequently be pulled away from the backing layer of the laminate
and be applied elsewhere as intended. Highly accurate face-layer
cutting about the graphics is obviously highly desirable.
[0004] This is but one example in which highly accurate sheet
cutting is desirable. In many other situations, highly accurate
sheet cutting may not involve face-cutting, but through-cutting, in
which the full thickness of the sheet is cut about a graphic on the
sheet. And in many situations, rather than highly accurate cutting,
highly accurate scoring, creasing, line embossing or the like, in
each case, of course, along a line the varying direction of which
is determined by the shape of the graphic. Together these types of
operations on sheets with respect to graphics thereon are referred
to herein as "narrow-path-processing." For convenience, the prior
art problems and the invention herein which solves such problems
will be discussed primarily with reference to sheet-cutting
apparatus.
[0005] A method and associated apparatus which addresses many of
the problems encountered in such processing of sheet material is
the i-cut.TM. vision cutting system from Mikkelsen Graphic
Engineering of Lake Geneva, Wisconsin, and is the subject of a
pending United States patent (Ser. No. 09/678,594) filed on Oct. 4,
2000. The invention described in such document is a method and
apparatus for achieving highly improved accuracy in cutting around
graphics in order to fully adjust for two-dimensional distortion in
the sheets from which the graphics will be cut, including
distortion of differing degrees in one dimension or along one
direction on the sheet of material. The distortion may be from the
printing process or from some other post-printing process such as
material handling or during the cutting process itself. This
invention also provides improved speed and accuracy in
narrow-path-processing and greater efficiency of material
usage.
[0006] In some cases, such as in the i-cut.TM. system from
Mikkelsen Graphic Engineering, a flatbed plotter is used. These are
devices having a positionally-controlled cutting implement above a
flat work surface on which the sheet to be cut rests. The cutting
implements are controlled based on controller-supplied instructions
based on the X-Y coordinates necessary to achieve cutting along the
intended path, such as about the graphic.
[0007] Achieving greater speed and overall efficiencies in
narrow-path-processing is a continuing challenge encountered with
such systems. One source of inefficiency is the manual intervention
often required to adjust the initial position and alignment of the
sheet on the work surface of the cutting apparatus. Sheets of
material on which graphics have been previously printed are placed
on the work surface of the cutting apparatus, either manually or by
automatic sheet-feeding equipment. In either of these set-up
situations, the cutting apparatus must determine the position and
orientation of the sheet on the work surface in order to proceed
accurately with the cutting process. If the operator or automatic
sheet-feeder places the sheet of material on the work surface such
that it is outside of the area or region of alignment on the work
surface which the cutting system expects to find the sheet, manual
intervention may be necessary to adjust the placement of the sheet
to within the required initial region in order for the process to
continue beyond this initial set-up step. Another source of
inefficiency is the time-consuming step which may be required to
allow the system to determine the initial position and orientation
of the sheet on the work surface.
[0008] Another source of inefficiency is the requirement that
information pertaining to a specific graphic be created and entered
into the processing controller. Such information may require
additional scanning of each sheet of material on which graphics are
applied or otherwise inputting data concerning X-Y positions, angle
orientations, scale factors, types or shapes of marks, graphic
boundaries, etc.
[0009] Another measure of efficiency is the amount of material
waste which is produced during narrow-path-processing. Depending on
volumes of material processed and the cost of the material used,
the amount of waste may be important to minimize in order to
increase overall process efficiency.
[0010] Despite the significant advances represented by the
i-cut.TM. system, these advances have not yet achieved the highest
levels of performance which potentially can be reached by automated
cutting systems. Further increases in efficiency (precision, speed
and efficiency of operation, and material usage) are highly
desirable in automated cutting systems.
OBJECTS OF THE INVENTION
[0011] It is an object of this invention to provide an improved
method for precision preparation of graphics from sheets and other
narrow-path-processing with respect to graphics on sheet materials
of various kinds, thereby overcoming some of the problems and
shortcomings of the prior art.
[0012] Another object of this invention is to provide a method for
reducing the time to recognize a specific graphic or sheet of
material and identify processing information pertaining to the
graphic and/or sheet.
[0013] Another object of the invention is to minimize or completely
eliminate the need for manual intervention by an operator in the
inputting of layout information related to specific graphics or
sheets of material.
[0014] Another object of this invention is to provide an improved
method which increases the speed of preparing processes graphics on
sheets of material.
[0015] Another object of this invention is to provide an improved
method which automate the cutting and other narrow-path-processing
of sheet material as much as possible.
[0016] Another object of this invention is to provide an improved
method which reduces material waste in cutting and other
narrow-path-processing of sheet material.
[0017] Another object of the invention is to provide a improved
method which provides for automatic determination of sheet position
and orientation of for processing around graphics on the sheet in
order to fully adjust for two-dimensional distortion in the sheets
from which the graphics will be processed.
[0018] These and other objects of the invention will be apparent
from the following descriptions and from the drawings.
SUMMARY OF THE INVENTION
[0019] The instant invention overcomes the above-noted problems and
shortcomings and satisfies the objects of the invention. The
invention is an improved method automatically preparing graphics on
a sheet of material. Stated more broadly, the invention is an
improved method and apparatus for narrow-path-processing with
respect to graphics images on sheets, including by cutting,
creasing, scoring or the like around such images. Of particular
note is that the instant invention brings high speed and improved
efficiency, including minimizing material waste and eliminating
certain manual intervention, to the precision processing of
graphics images from sheets bearing such images, including without
limitation in situations in which there has been distortion of
various kinds in the sheets, including two-dimensional
distortion.
[0020] The method of this invention, stated with respect to
automatically preparing graphics from sheets of material including
such graphics, includes as a first step applying a graphic and at
least one registration mark on a sheet of material in positions
according to layout data. The registration mark is preferably
applied at and about the graphic in known predetermined positions
with respect to the graphic, or more particularly, with respect to
the perimeter thereof which will be processed. In certain preferred
embodiments at least one registration mark is provided within the
graphic. In other certain preferred embodiments, at least one
registration mark is in an initial-position/orientation-determining
subset which is located on no more than one side of the
graphic.
[0021] As used herein, the word "perimeter" means the intended
processing path around a graphic, whether or not the intended
processing path is an outer edge of the graphic or an inner edge
(such as from removal of the inside of the letter "D").
[0022] The method involves: transferring the layout data to a
processing controller; placing the sheet of material on a
sheet-receiving surface; sensing the position of the registration
mark on the sheet of material; and utilizing the layout data and
the position of the registration mark to precisely process or cut
around the graphic on the sheet of material. The transfer of layout
data to the processing controller may be performed by downloading
the data from the graphic and mark application device to a disc and
uploading the data to the controller, through a network connection
between the application device and the controller or otherwise.
This method allows the identification of the graphic and/or sheet
and the retrieval of the respective layout data to occur rapidly
with a minimum of manual intervention and processing to occur
precisely even if two-dimensional distortion of the sheet has
occurred prior to processing.
[0023] It is highly preferred that the controller furnish
instructions for the sensing and processing operations so that the
determinations involving sensing and processing are carried out
swiftly and on a continuing basis as one or more graphics are
processed from a sheet and as additional sheets are processed. The
controller further facilitates the efficiency improvements of this
invention.
[0024] In preferred embodiments the registration marks may be
multiple lines applied along an edge of the sheet of material,
multiple marks applied along an edge of the sheet of material,
multiple marks applied on the sheet of material surrounding the
graphic, or a bar code. If a bar code, the method preferably
includes the further steps of: reading the bar code to identify the
sheet of material on the sheet-receiving surface; and finding the
layout data corresponding to the graphic and registration mark
applied on the sheet of material. It is preferred that the bar code
simply identify the proper file associated with the sheet or
graphic. Therefore, because the bar code need only communicate a
file name or file number, it can be quite small.
[0025] In other preferred embodiments, the layout data comprises
graphic data and registration mark data. In such embodiments, the
method preferably further includes the steps of downloading the
graphic data and registration mark data to at least one file,
transferring the file or files to the processing controller; and
uploading the graphic data and registration mark data from the file
or files to the processing controller. The registration mark data
may include data pertaining to X-Y position, angle orientation,
scale factor, and/or mirroring information. The graphic data may
including nesting information (i.e., the optimized spacing of
multiple graphics at various positions on the sheet), mirroring
information related to mirrored graphics, contour information,
perimeter information, X-Y position, angle orientation, and/or
scale factor.
[0026] A preferred method further includes the steps of: after
placing the sheet of material on the sheet-receiving surface,
sensing the registration mark in a field of view of a main sensor
and utilizing the layout data to determine a position and
orientation of the sheet of material; if the registration mark is
not in an expected location, automatically determining a coordinate
region of the registration mark on the sheet-receiving surface by
enlarging the field of view of the main sensor and locating the
coordinate region of the registration mark within the enlarged
field of view; in response to determining the coordinate region of
the registration mark, automatically repositioning the main sensor
to the coordinate region by shrinking the field of view of the main
sensor such that the registration mark is within the field of view
of the main sensor; and utilizing the layout data and the position
of the registration mark to precisely process around the graphic on
the sheet of material.
[0027] In another preferred method, the sensing step includes
moving a sensor operatively connected to the sheet-receiving
surface along the surface to detect the position of the
registration mark and the utilizing step includes communicating the
position of the registration mark from the sensor to the processing
controller.
[0028] In another description of the invention, the method for
automatically preparing at least one graphic on a sheet of material
comprises: applying the graphic on the sheet of material in a
position according to layout data, the layout data including a
predetermined approximate position and orientation of the graphic
with respect to a set of reference features of the sheet of
material; transferring the layout data to a processing controller;
placing the sheet of material on a sheet-receiving surface;
automatically determining whether the reference features are in an
expected coordinate region on the sheet-receiving surface; if the
reference features of the sheet of material are not in the expected
coordinate region, automatically determining the coordinate region
of the reference features on the sheet-receiving surface; sensing
metrics of the reference features to determine a position and
orientation of the sheet of material; inferring therefrom the
approximate position of the graphic; and utilizing the layout data
and precise position of the graphic to precisely process around the
graphic on the sheet of material. Transfer of the layout data to
the processing controller may be through a network connection, by
downloading the layout data to a disc and uploading the layout data
from the disc to the processing controller, or by other means.
[0029] In another description of the invention, the method
comprises the steps of: applying the graphic on the sheet of
material in a position according to layout data; applying a
plurality of registration marks on the sheet of material at and
about the graphic in predetermined positions with respect thereto
at the time the graphic is applied according to layout data, the
plurality of registration marks including an
initial-position/orientation-determining subset located on no more
than one side of the graphic; transferring the layout data to a
processing controller; placing the sheet of material on a
sheet-receiving surface; sensing the subset to ascertain a position
and orientation of the sheet of material and approximate positions
of the plurality of registration marks thereon; sensing precise
positions of the registration marks on the sheet of material; and
utilizing the layout data and the precise positions of the
registration marks with respect to the graphic to precisely process
around the graphic on the sheet of material.
[0030] Such a method may also include the steps of retaining the
sheet of material on the sheet-receiving surface at a location
thereon such the sheet of material overlaps the X and Y coordinate
grid, acquiring X and Y coordinates which are overlapped by the
registration marks and comparing the X and Y coordinates which are
overlapped by the registration marks with a reference set of X and
Y coordinates.
[0031] In certain preferred embodiments the layout data includes
reference X and Y coordinates for the registration marks and the
predetermined positions thereof with respect to the perimeter of
the graphic when the graphic and registration marks are applied to
the sheet of material and the utilizing step further includes
setting an optimized processing path based on the comparing step,
such optimized processing path corresponding to the perimeter of
the graphic.
[0032] In another description, the invention represents an
improvement on methods for preparing graphics on a sheet of
material which include the steps of: applying the graphic and at
least one registration mark on the sheet of material, placing the
sheet on a sheet-receiving surface, sensing positions of the
registration marks and utilizing the positions of the registration
marks to process around the graphic on the sheet of material. The
improvement wherein a processing controller utilizes processing
data to process around the graphic on the sheet of material and
comprising the steps of creating and using layout data to apply the
graphic and registration marks to the sheet of material;
transferring the layout data to the processing controller;
identifying the sheet placed on the sheet-receiving surface;
locating the layout data which pertains to the identified sheet;
and utilizing the layout data as the processing data. This improved
method allows the processing to occur efficiently and rapidly with
a minimum of manual intervention and to occur precisely despite
two-dimensional distortion of the sheet prior to processing.
[0033] In preferred embodiments of the invention, the
initial-position/orientation-determining subset is a pair of
registration marks in tandem relationship to each other. The term
"tandem relationship" as used herein means spaced closer to one
another than the average spacing between other registration marks
applied on the sheet of material. For example, on a sheet of
material one meter by one meter in size with graphics applied
including registration marks around the perimeters of the graphics,
two registration marks applied near one corner of the sheet with a
25 mm space between the centers of the two marks are said to be in
tandem relationship with each other.
[0034] In certain preferred embodiments, each of the registration
marks of the pair is a round area, and the sensing step includes
processing sensed data to find the mathematical centers thereof.
Further, in highly preferred embodiments, all of the registration
marks are round areas, and the sensing step includes processing
sensed data to find the mathematical centers thereof.
[0035] In highly preferred embodiments, the method includes the
additional step of placing the sheet on a sheet-receiving surface
having an X and Y coordinate grid and retaining the sheet at a
user-selected location thereon such that the sheet of material
overlaps the X and Y coordinate grid. In such preferred
embodiments, the sensing of the precise positions of the
registration marks on the sheet includes the step of acquiring the
X and Y coordinates which are overlapped by the registration marks.
Further, preferred embodiments of the invention include in the
processing process the step of comparing the X and Y coordinates
which are overlapped by the registration marks with a reference set
of X and Y coordinates. In highly preferred embodiments, the
comparing step is carried out by the controller.
[0036] In certain preferred embodiments, the controller has a
programmed set of predetermined processing instructions which
includes reference X and Y coordinates for the registration marks
and also includes the predetermined positions thereof with respect
to the perimeter of the graphic when the graphic and registration
marks are first applied to the sheet. Such processing instructions
are preferably delivered to the controller as layout data from the
graphic and registration mark application. In such embodiments, the
processing step includes setting a final (optimized) processing
path based on the comparing step, such final processing path
corresponding to the perimeter of the graphic of the sheet even
though such perimeter is distorted during the uncut life of the
sheet.
[0037] In certain preferred embodiments, the sheet is a laminate
having (a) a face layer which bears one or more graphics and
registration marks corresponding to each, and (b) a backing layer,
and the processing is face cutting only. This allows preparation of
highly accurate decals, which can later be removed from the backing
layer.
[0038] In many cases, depending on the size of the sheet, it is
preferred that there be a plurality of graphics on each sheet and a
corresponding plurality of sets of the registration marks at or
about each graphic.
[0039] In a highly preferred embodiment of the invention, the
method involves: placing the sheet on a sheet-receiving surface;
sensing the subset in the field of view of a main sensor to
ascertain the position and orientation of the sheet and to infer
the approximate positions of the plurality of marks; if the subset
is not in an expected location, automatically determining the
coordinate region of the subset on the sheet-receiving surface;
sensing the precise positions of the marks; and processing the
graphic from the sheet in response to the precise positions of the
marks with respect to the graphic. This embodiment of the method
allows the sensing of the registration marks to occur rapidly with
a minimum of manual intervention and cutting (or other
narrow-path-processing) to occur precisely, whether or not
two-dimensional distortion of the sheet is present prior to
processing.
[0040] In certain preferred embodiments of the invention,
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. In
one such embodiment, movement of the main sensor is in the plane of
the sheet-receiving surface. In another such embodiment, moving the
main sensor includes rotating the main sensor such that the field
of view changes.
[0041] In certain embodiments of the invention, the automatic
determining step includes enlarging the field of view of the main
sensor, thereby locating the coordinate region of the subset within
an enlarged field of view. The main sensor is then repositioned,
including shrinking the field of view of the main sensor, such that
the subset is within the field of view of the main sensor. In one
such embodiment, enlarging and shrinking the field of view of the
main sensor is performed by zooming a lens of the main sensor. In
another such embodiment, the enlarging and shrinking steps are
performed by increasing and decreasing respectively the distance
between the main sensor and the sheet-receiving surface.
[0042] In another embodiment of the invention, automatically
determining the location of the coordinate region of the subset
involves locating the coordinate region of the subset within the
field of view of a secondary sensor.
[0043] In certain embodiments of the invention, automatic
determination 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 extra
marks printed on the sheet of material outside the coordinate
region of the subset. In particular embodiments of the invention,
the automatic determining step includes determining from the
directive indicia the direction and distance from the expected
location to the actual location and repositioning the main sensor
by moving it in the determined direction for the determined
distance.
[0044] Another aspect of the inventive technology disclosed herein
involves an alternative approach to ascertaining the position and
orientation of the sheet of material. The method involves: placing
the sheet on a sheet-receiving surface; sensing a set of reference
features of the sheet of material (such as edges, a corner, or
elements of a graphic printed on the sheet) in the field of view of
a main sensor to ascertain the position and orientation of the
sheet and to infer the approximate positions of the plurality of
marks; if the reference features are not in an expected location,
automatically determining the coordinate region of the reference
features on the sheet-receiving surface and then sensing the
metrics of the reference features in order to then ascertain such
position and orientation and infer such approximate positions;
sensing the precise positions of the marks; and processing the
graphic from the sheet in response to the precise positions of the
marks with respect to the graphic.
[0045] The coordinate region of the set of reference features on
the sheet-receiving surface is the area thereof which, when
contained within the field of view of the main sensor, enables
main-sensor sensing of the set with precision sufficient to
determine the position and orientation of the sheet of material on
the sheet-receiving surface such that the various registration
marks can be automatically found to enable subsequent precision
sensing thereof.
[0046] As used herein, the term "metrics," applied in
characterizing a reference feature, refers to the numerical
parameters which can be used by the device to describe the position
and orientation of the reference feature and, in combination with
other metrics of this and other reference features, can be used to
ascertain the position and orientation of the sheet of material on
the sheet-receiving surface. For example, a straight edge of a
sheet of material defines a line which lies at an angle with
respect to the coordinate system axes of the sheet-receiving
surface. Such angle is one such "metric." The corner of a sheet
defined by the intersection of two such edges defines a point
within the coordinate system, and the x,y coordinates of the corner
point are two more such "metrics." Other metrics might include,
among other things, certain geometric descriptors of shapes,
positions, and orientations of graphical images within the graphic
itself.
[0047] In a fashion similar to embodiments wherein a subset of
initial-position/orientation-determining marks is employed, other
embodiments of the inventive technology include the alternative use
of a set of reference features.
[0048] The apparatus of this invention is a device for processing a
graphic at the perimeter thereof from a sheet of material, the
sheet having a plurality of registration marks at and about the
graphic, the plurality of registration marks including an
initial-position/orientation-determining subset that is located on
no more than one side of the graphic. The registration marks are
simply added during the printing of the graphic.
[0049] The inventive apparatus includes: a sheet-receiving surface;
a main sensor, preferably a CCD area image sensor; for sensing the
subset in the field of view of the main sensor to ascertain the
position and orientation of the sheet and to infer approximate
positions of the plurality of marks and for sensing the precise
positions of the marks; a cutter or other processing device
operatively connected to the main sensor and movable about the
sheet-receiving surface, the cutter processing the graphic from the
sheet of material in response to the precise positions of the
registration marks sensed by the main sensor; and a controller for
controlling movement of the cutter along the sheet-receiving, the
controller including a set of initialization instructions
corresponding to (a) predetermined approximate positions of the
initial-position/orientation-determining subset on the sheet and
(b) the relative positions of the remaining registration marks
thereon with respect to the position of the subset. The invention,
as already indicated, allows the sensing of the registration marks
to occur rapidly and processing to occur precisely despite
two-dimensional distortion of the sheet prior to processing.
[0050] In preferred embodiments, the initialization instructions of
the controller also include instructions for sensing the precise
position and orientation of the subset, whereby the approximate
positions of the remaining registration marks are inferred to
facilitate sensing of the precise positions of the remaining
registration marks. Further, the controller includes a set of
predetermined processing instructions therein corresponding to the
perimeter of the graphic and the predetermined position thereof
with respect to predetermined positions of the registration marks
when the graphic and registration marks are first applied to the
sheet, the controller moving the cutter along the sheet-receiving
surface in response to a comparison of (a) the locations of the
registration marks sensed by the sensor on the sheet with (b) the
set of predetermined processing instructions.
[0051] In highly preferred embodiments of the invention, the
apparatus also includes 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.
[0052] In other highly preferred embodiments of the invention, the
coordinate region locator includes a controller with a set of
locating instructions for 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.
[0053] In certain preferred embodiments, 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.
[0054] Another embodiment of 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.
[0055] In certain embodiments of the invention, 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.
[0056] In another embodiment of the invention, 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
determining the coordinate region of the subset by sensing the
directive indicia, and repositioning the main sensor in response
thereto, such that the subset is within the field of view of the
main sensor.
[0057] Another aspect of the inventive apparatus disclosed herein
involves an alternative approach to ascertaining the position and
orientation of the sheet of material. In some highly preferred
embodiments, the apparatus also includes a reference feature
identifier which, if the reference features are not in an expected
coordinate region on the sheet-receiving surface, automatically
determines the coordinate region of the reference features, and
which, when the coordinate region of the reference features is
known, senses the metrics of the reference features in order to
infer the approximate positions of the registration marks.
[0058] In a fashion similar to embodiments in which a subset of
initial-position/orientation-determining marks is employed, other
embodiments of the inventive apparatus include the alternative use
of a set of reference features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] FIG. 1 is a perspective view of an automatically controlled
processing apparatus employing the present invention.
[0060] FIG. 2 is a top view of a sheet of sheet material with
pre-printed graphics and registration marks, including an
initial-position/orientation-determining subset of marks.
[0061] FIG. 3A is a top view of a sheet of material on a
sheet-receiving surface, illustrating a coordinate region of the
subset and a field of view of a main sensor which does not contain
the coordinate region of the subset.
[0062] FIG. 3B is a top view of a sheet of material on a
sheet-receiving surface, illustrating a coordinate region of a set
of reference features and a field of view of a main sensor which
does not contain the coordinate region of the set.
[0063] FIG. 4A is a top view of a portion of a sheet-receiving
surface, a portion of a sheet of material, and one predetermined
pattern of movement of the main sensor, illustrated by consecutive
fields of view of the main sensor.
[0064] FIG. 4B is a top view of a portion of a sheet-receiving
surface, a portion of a sheet of material, and a second
predetermined pattern of movement of the main sensor, illustrated
by consecutive fields of view of the main sensor.
[0065] FIG. 4C is a top view of a portion of a sheet-receiving
surface, a portion of a sheet of material, and one predetermined
pattern of movement of the main sensor, illustrated by consecutive
fields of view of the main sensor.
[0066] FIG. 4D is a top view of a portion of a sheet-receiving
surface, a portion of a sheet of material, and a second
predetermined pattern of movement of the main sensor, illustrated
by consecutive fields of view of the main sensor.
[0067] FIG. 5 is a schematic side view of sheet-receiving surface
and a main sensor with a zoom lens.
[0068] FIG. 6 is a schematic side view of a sheet-receiving surface
with a main sensor height adjustor.
[0069] FIG. 7 is a schematic side view of a sheet-receiving surface
with a main sensor and a secondary sensor.
[0070] FIG. 8 is a schematic side view of a sheet-receiving surface
with a main sensor which rotates to change its field of view.
[0071] FIG. 9A is a top view of a sheet of material with
pre-printed graphics, an initial-position/orientation-determining
subset, and one type of directive indicia.
[0072] FIG. 9B is a top view of a sheet of material with
pre-printed graphics, an initial-position/orientation-determining
subset, and two additional types of directive indicia.
[0073] FIG. 10A is a top view of a sheet of material with
pre-printed graphics and a set of reference features including a
uniqueness feature comprising a corner cut-off.
[0074] FIG. 10B is a top view of a sheet of material with
pre-printed graphics, with a set of reference features including a
portion of the graphics image near one corner of the sheet.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0075] Referring to FIG. 1, a partially cut away view of a cutting
or processing device 10 is shown. Cutting device 10 has a housing
12 which may contain the controller 50 and a sheet-receiving
surface 16. Cutting device 10, which is shown with a sheet 40
positioned on sheet-receiving surface 16, is also known as a
flatbed plotter or cutter in the art and may be a Zund plotter,
manufactured by Zund System Technik HG, or a Wild plotter, to give
two examples.
[0076] Cutting device 10 includes two longitudinal guide rails 14
mounted on housing 12 and a transverse member 18 is suspended
between longitudinal guide rails 14. Transverse member 18 is driven
by a motor (not shown) along guide rails 14. A cutting tool 20
rides on transverse member 18. Cutting tool 20 has a cutting knife
(not shown).
[0077] A main sensor 22 is shown attached to cutting tool 20. While
sensor or detector 22 is shown attached to cutting tool 10, it is
not necessary for it to be attached to it. Main sensor 22 may be an
optical detector responsive to registration marks on sheet 40.
[0078] Cutting tool 20 moves along transverse member 18 and is
driven by a motor (not shown). Cutting tool 20 is capable of moving
laterally or longitudinally along work surface 16. Cutting tool 20
may have pressure and tangential controlled tungsten carbide
blades, tungsten carbide blades, other blades that are generally
known or lasers, which are not shown. The cutter driver (not shown)
which controls cutting tool 20 is standard and is known in the
art.
[0079] Referring to FIG. 2, registration marks 44 are pre-printed
on sheet 40. Sheet 40 has many registration marks 44 preprinted
thereon, including several around each of the graphics 42a and 42b
which are intended to be processed from sheet 40. (A variety of
shapes, sizes, and colors for the marks are possible. In some
embodiments, registration marks are circles, either filled or
unfilled, of equal size. They may be anywhere from 3 mm to 12 mm in
diameter, with a preferred outer diameter of 6.3 mm.) Registration
marks 44 are adjacent to, but not contiguous with, the perimeters
of preprinted graphics 42a and 42b.
[0080] The registration marks include an
initial-position/orientation-determining subset 46 of marks which
is on only one side of the graphics 42a and 42b. This subset 46 is
placed only to one side of graphics 42a and 42b to facilitate rapid
determination of the positions of subset 46 relative to work
surface 16. It is possible for there to be more than one subset of
unique initial-position/orientation-determining marks, but in such
cases only one such subset need be sensed.
[0081] Main sensor 22 is connected to the input of the controller,
part of the coordinate region locator (not shown as a discrete
element) by cables 28 and 30. The controller is also connected to
and drives cutting tool 20. The controller receives the input
external data and compares it to the format and content of
information which it has stored in it. For each graphic 42a and
42b, the information stored in the controller is the location of
the perimeter of the graphic relative to the locations of
registration marks 44 as printed on sheet 40. Specifically, the
controller has information defining the position of the
registration marks 44 and the intended processing paths,
information defining the position of the registration marks 44 with
respect to initial-position/orientation-determining subset 46 of
marks, and information defining the expected location of subset 46
on sheet-receiving surface 16.
[0082] After graphics 42a and 42b and registration marks 44 and
initial-position/orientation-determining subset 46 of marks have
been printed on sheet 40, sheet 40 is placed on sheet-receiving
surface 16 at an initial position and orientation. When the
controller instructs main sensor 22 to sense subset 46 but subset
46 is not found in the location expected by the controller, the
controller instructs main sensor 22 to move in a predetermined
pattern in order to determine the coordinate region of subset
46.
[0083] The controller instructs sensor 22 to find the precise
positions of the mathematical centers of
initial-position/orientation-determining subset of marks 46 and
defines these positions in X-Y coordinates of work surface 16. This
information is then used to determine the position and orientation
of sheet 40 on work surface 16. Once the position and orientation
of sheet 40 are known, the controller uses the stored information
on the relative location of registration marks 44, in conjunction
with sensors 22, to determine the precise positions of registration
marks 44.
[0084] The controller compares the actual distance between the
three registration marks (44) which are closest to a point on the
intended processing point, and adjusts the processing path
according to the changes between these registration marks using the
information for their locations when printed on sheet 40. The
adjustments are made by making changes in the X-Y coordinates of
points along the processing path.
[0085] The sensor or detector 22 may be a CCD camera, which is
known in the art. The cutter drivers (not shown) are also known in
the art. In operation, sensor 22 is caused to be positioned over a
registration mark 44. Sensor 22 finds the mathematical center of a
registration mark 44 and defines its position in X-Y coordinates of
work surface 16. Two other registration marks 44 are located and
their centers are defined by X-Y coordinates in like manner.
[0086] These data are inputted to the processing controller where
the actual locations of registration marks 44 on ready-to-be-cut
sheet 40 are compared to those of the registration marks in the
predetermined processing instructions. The predetermined processing
path which is a collection of X-Y coordinate sets is adjusted
according to the actual X-Y coordinates of registration marks 44.
These comparisons are made interactively throughout the cutting
process, making the process a dynamic process.
[0087] The processing path is adjusted according to the actual
coordinates of the three registration marks 44 closest to a
processing point. When the processing of an individual graphic is
completed, cutting tool 20 is caused to be lifted and moved to the
next graphic and the process is repeated.
[0088] In the operating mode, sheet material 40 is placed on work
surface 16 and may be held in place by a vacuum which acts through
the work surface. The processing of graphics 42a and 42b is
effected by movement of computer-controlled cutting tool 20 and
computer-controlled transverse rail 18. The predetermined
processing instructions contained in the controller are based upon
the graphic which was originally printed on sheet 40. The
processing path is defined in X-Y coordinates.
[0089] As already noted, sensor 22 finds the locations of
registration marks 44 and defines them in X-Y coordinates. This
information is compared to the predetermined X-Y coordinates of the
registration marks, and the processing path along the perimeters of
the graphics are adjusted according to the changes in the location
of the three registration marks are closest to each processing
point. The processing path is optimized and modified dynamically as
the cutting proceeds; i.e., an appropriate final processing path is
determined.
[0090] FIG. 3A illustrates sheet 40 placed on sheet-receiving
surface 16 such that coordinate region 45 of subset 46 of marks is
not within initial field of view 48 of main sensor 22. FIG. 3A
illustrates this situation within the context of a coordinate
region locator. In the following detailed descriptions, two
approaches for ascertaining the position and orientation of sheet
40 are described in parallel fashion; one is a coordinate region
locator and the other is a reference feature identifier. Either of
these approaches can be used during the process of ascertaining the
position and orientation of sheet 40. The coordinate region locator
uses subset 46; the reference feature identifier uses a reference
feature set (e.g., see set 49 in FIG. 3B). Such subset of
registration marks and such reference feature set each, by itself,
uniquely indicates such position and orientation.
[0091] Thus, referring to FIG. 3B, within the context of a
reference feature identifier, sheet 40 is shown placed on
sheet-receiving surface 16. A reference feature set 49 (shown as
two edges at one corner of sheet 40) is within coordinate region 47
of sheet-receiving surface 16, with region 47 not within initial
field of view 48 of main sensor 22. Referring back to FIG. 1, main
sensor 22 is connected to the input of the controller, part of the
reference feature identifier (not shown as a discrete element) by
cables 28 and 30. The controller is also connected to and drives
cutting tool 20. The controller receives the input external data
and compares it to the format and content of information which it
has stored in it. For each graphic 42a and 42b, the information
stored in the controller is the location of the perimeter of the
graphic relative to the locations of registration marks 44 as
printed on sheet 40. Specifically, the controller has information
defining the position of the registration marks 44 and the intended
processing paths, information defining the position of the
registration marks 44 with respect to reference feature set 49, and
information defining the expected location of set 49 on
sheet-receiving surface 16.
[0092] After graphics 42a and 42b and registration marks 44 have
been printed on sheet 40, sheet 40 is placed on sheet-receiving
surface 16 at an initial position and orientation, illustrated in
FIG. 3B. When the controller instructs main sensor 22 to identify
set 49 but set 49 is not found in the location expected by the
controller, the controller instructs main sensor 22 to move in a
predetermined pattern. The location expected by the controller is
represented by initial field of view 48 of main sensor 22.
[0093] FIGS. 4A and 4B illustrate two predetermined patterns along
which main sensor 22 is directed to move by the set of instructions
of the coordinate region locator. In FIGS. 4A and 4B, one corner of
sheet-receiving surface 16 is shown, along with one corner of sheet
40 containing subset 46. In both of these figures, movement of main
sensor 22 is illustrated by consecutive fields of view F1, F2, F3 .
. . , etc., with initial field of view 48 (F1) aligning with the
expected location of subset 46. FIG. 4A illustrates a predetermined
outwardly-expanding spiral pattern, and FIG. 4B illustrates a
predetermined L-shaped pattern. These examples of predetermined
patterns are but two of many patterns which can be used in the
coordinate region locator to place coordinate region 45 of subset
46 within the field of view of main sensor 22.
[0094] Information obtained by sensing subset 46 is then used to
determine the position and orientation of sheet 40 on work surface
16. Once the position and orientation of sheet 40 are known, the
controller uses the stored information on the relative location of
registration marks 44, in conjunction with main sensor 22, to
determine the precise positions of registration marks 44.
[0095] In a manner similar to FIGS. 4A and 4B, FIGS. 4C and 4D
illustrate the same two predetermined patterns along which main
sensor 22 is directed to move, but in this case by the controller
of a reference feature identifier. The metrics obtained by sensing
set 49 are then used to determine the position and orientation of
sheet 40 on work surface 16. Once the position and orientation of
sheet 40 are known, the controller uses the stored information on
the relative location of registration marks 44, in conjunction with
main sensor 22, to determine the precise positions of registration
marks 44.
[0096] While FIGS. 4A through 4D illustrate predetermined patterns
made of a series of discrete fields of view, the patterns of this
invention also contemplate continuous movement and continuous
viewing by the coordinate region locator or the reference feature
identifier.
[0097] FIG. 5 shows schematically another embodiment of the
coordinate region locator. Main sensor 22 includes a zoom lens 26
which is used to enlarge the field of view of main sensor 22. When
subset 46 is not in an expected location, the controller of the
coordinate region locator instructs the zoom lens to zoom out to
enlarge the field of view and determines the position of subset 46
in this enlarged field of view. Then, main sensor 22 is
repositioned over sheet-receiving surface 16 such that coordinate
region 45 of subset 46 is centered within the field of view of main
sensor 22, after which main sensor 22 zooms back in, shrinking its
field of view in order to allow precise sensing of the marks of
subset 46. Two alternative procedures include zooming main sensor
22 back in either before or during such repositioning; regardless
of which procedure is programmed, coordinate region 45 of subset 46
will end up within the shrunken field of view of main sensor
22.
[0098] FIG. 5 also can be used to illustrate another embodiment of
the reference feature identifier. Main sensor 22 includes a zoom
lens 26 which is used to enlarge the field of view of main sensor
22. When reference feature set 49 is not in an expected location,
the controller of the reference feature identifier instructs the
zoom lens to zoom out to enlarge the field of view and determines
the position of set 49 in this enlarged field of view. Then, main
sensor 22 is repositioned over sheet-receiving surface 16 such that
coordinate region 47 of set 49 is centered within the field of view
of main sensor 22, after which main sensor 22 zooms back in,
shrinking its field of view in order to allow precise sensing of
the metrics of reference feature set 49. Two alternative procedures
include zooming main sensor 22 back in either before or during such
repositioning; regardless of which procedure is programmed,
coordinate region 47 of set 49 will end up within the shrunken
field of view of main sensor 22.
[0099] FIG. 6 shows schematically yet another embodiment of the
coordinate region locator. Main sensor 22 is mounted on main-sensor
height adjustor 28. Main sensor 22 is moved along track 27 by a
motor (not shown) away from and toward sheet-receiving surface 16
to enlarge and shrink respectively the field of view of main sensor
22. When subset 46 is not in an expected location, the controller
of the coordinate region locator instructs main sensor 22 to move
away from sheet-receiving surface 16, thereby enlarging the field
of view of main sensor 22. The coordinate region locator then
determines the position of subset 46 and directs the repositioning
of main sensor 22 over sheet-receiving surface 16. Then, main
sensor 22 is moved back toward sheet-receiving surface 16 to shrink
the field of view, such that coordinate region 45 of subset 46 is
within the field of view of main sensor 22.
[0100] In a similar fashion to the description of FIG. 5, the
physical configuration shown in FIG. 6 also can be used as a
portion of a reference feature identifier, with the controller (not
shown) containing a set of instructions to instruct height adjustor
28 and to respond to reference feature set 49 (see FIGS. 4C and
4D).
[0101] FIG. 7 shows schematically a coordinate region locator which
includes secondary sensor 62 which has a larger field of view than
main sensor 22. Operation of the coordinate region locator in this
embodiment is similar to the operation of the embodiment
illustrated in FIG. 6, except that secondary sensor 62, the
vertical position of which is fixed, takes the place of main sensor
22 in its raised position.
[0102] As with the descriptions of FIGS. 5 and 6, the physical
configuration shown in FIG. 7 also can be used as a portion of a
reference feature identifier, with the controller (not shown)
containing a set of instructions to instruct secondary sensor 62
and main sensor 22 and tailored to respond to reference feature set
49 (see FIGS. 4C and 4D).
[0103] FIG. 8 illustrates schematically a coordinate region locator
which includes rotation around one of two axes parallel to the
plane of sheet-receiving surface 16. Rotation about one such axis
is illustrated in FIG. 8. When subset 46 is not in an expected
location, the controller (not shown) of the coordinate region
locator instructs main sensor 22 to rotate in a manner which
changes the field of view of main sensor 22, thereby allowing the
coordinate region locator to find coordinate region 45 of subset 46
outside of the initial field of view of main sensor 22. Main sensor
22 then determines the position of coordinate region 45 of subset
46, is repositioned over sheet-receiving surface 16, and rotated
back to a normal vertical orientation such that coordinate region
45 of subset 46 is within the field of view of main sensor 22.
[0104] Again, as with the descriptions of FIGS. 5, 6, and 7, the
physical configuration shown in FIG. 8 also can be used as a
portion of a reference feature identifier, with the controller (not
shown) containing a set of instructions to instruct main sensor 22
to rotate in a manner which changes the field of view of main
sensor 22, thereby allowing the reference feature identifier to
find coordinate region 47 of set 49 (see FIGS. 4C and 4D) outside
of the initial field of view of main sensor 22. Main sensor 22 then
determines the position of coordinate region 47 of set 49, is
repositioned over sheet-receiving surface 16, and rotated back to a
normal vertical orientation such that coordinate region 47 of set
49 is within the field of view of main sensor 22.
[0105] FIGS. 9A and 9B illustrate several different types of
directive indicia as part of other embodiments of a coordinate
region locator. Shown in FIGS. 9A and 9B are corner portions of
sheet-receiving surfaces 16 with corner portions of sheet 40
thereon. The corner portions of sheet 40 include subset 46.
[0106] FIG. 9A shows circular directive indicia 80 which surround
subset 46 such that the coordinate region locator can determine the
location of coordinate region 45 of subset 46 when a portion of
circular directive indicia 80 is within the field of view of main
sensor 22, the curvature and orientation of circular indicia 80
indicating such location. Such circular directive indicia can be
continuous as shown, or can be severely discontinuous as necessary
to accommodate the graphics. In a similar manner, the size and
orientation of arrow directive indicia 81 surrounding subset 46 in
FIG. 9B indicate the location of coordinate region 45 of subset
46.
[0107] FIG. 9B also illustrates edges 83 of sheet 40, a corner 82
of sheet 40, and graphics image portion 84 which can be used in
other embodiments of the coordinate region locator. These three
types of directive indicia are but examples of alternative
directive indicia which can be used by a coordinate region locator
to locate coordinate region 45 of subset 46.
[0108] FIGS. 10A and 10B illustrate two additional types of
reference feature sets (in addition to those illustrated in FIGS.
3B, 4C, and 4D) which can be identified by the reference feature
identifier. Shown in FIG. 10A is sheet 40 with graphics 42a and 42b
thereon and reference feature set 41 at the upper left corner of
sheet 40. Shown in FIG. 10B is sheet 40 with graphics 42a and 42b
thereon and reference feature set 51 at the upper left corner of
sheet 40.
[0109] FIG. 10A shows reference feature set 41 as a corner of sheet
40 which has a small section of the corner cut off. One group of
metrics of set 41 includes the angle (with respect to the
coordinate axes of surface 16, not shown) of the line defined by
the edge of the cutoff corner and the two end points of the cutoff
corner. If only one corner of sheet 40 has been cut off, then this
group of metrics is adequate to uniquely ascertain position and
orientation of sheet 40. Another group of metrics can include the
angles of the cutoff edge and the two edges which meet the cutoff
at its end points (all measured with respect to the coordinate axes
of surface 16). In fact, there are numerous combinations of metrics
which can be used based on such reference features. Further, if it
can be assumed that the initial placement of sheet 40 on surface 16
is such that a particular corner is the corner nearest initial
field of view 48 of sensor 22, then a smaller group of metrics is
adequate for determining the position and orientation of sheet 40.
In this way, the metrics of reference feature set 49 shown in FIGS.
3B, 4C, and 4D can be the angle of the edges of set 49 with respect
to a known line of surface 16 or the angle of one edge and the
coordinates of the corner point.
[0110] FIG. 10B illustrates a different set 51 of reference
features comprised of certain features of graphic 42a and a corner
of sheet 40. The group of metrics can be the coordinates of the
three points indicated by the arrows from the number 51, one of
which is the corner point itself. Just as in the description of set
41 in FIG. 10A, it will be apparent to those familiar with this
invention that other groups of metrics of set 51 can be used to
adequately determine the position and orientation of sheet 40 on
surface 16.
[0111] As indicated above, the method and apparatus of this
invention significantly speed the process of locating precise
positions of registration marks 44 and improve the efficiency of
the overall process, and these advantages are made possible
regardless of presence or absence of distortion in sheet 40
occurring after the graphics image and registration marks are
printed thereon. In operation, sensor 22 is caused to be positioned
over a registration mark 44. Sensor 22 finds the mathematical
center of a registration mark 44 and defines its position on work
surface 16. Two other registration marks 44 are located and their
centers are defined in like manner. These data are inputted to the
controller where the actual locations of registration marks 44 on
sheet 40 are compared to those of the registration marks in the
predetermined processing instructions--which are based on the
pre-distortion positions of the graphics image(s) and registration
marks 44. The predetermined processing path is adjusted according
to the actual (post-distortion) coordinates of registration marks
44. These comparisons are made interactively throughout the cutting
process, making the process a dynamic process. The processing path
is adjusted according to the actual coordinates of the three
registration marks 44 closest to a processing point. When the
processing of an individual graphic is completed, cutting tool 20
is caused to be lifted and moved to the next graphic and the
process is repeated.
[0112] The method and apparatus of this invention have a wide range
of applications in a variety of industries. The invention also has
application to sheets in the form of curved surfaces, in certain
situations. Furthermore, the applicability of the invention is not
limited to any particular kind or form of sheet.
[0113] Additionally, it should be noted that while two round marks
are shown as initial-position/orientation-determining subset of
marks 46, numerous other combinations of shapes and sizes of subset
marks are sufficient to determine the position and orientation of
sheet 40 on work surface 16. For example, with the sensor and
controller properly programmed, a single rectangular mark would
also provide sufficient information for this determination. In a
similar fashion, the reference feature sets described are but a few
of the many possible sets can be used in conjunction with a
reference feature identifier to uniquely ascertain position and
orientation of the sheet of material.
[0114] While the principles of this invention have been described
in connection with specific embodiments, it should be understood
clearly that these descriptions are made only by way of example and
are not intended to limit the scope of the invention.
* * * * *