Patent Application
20050166744
The present invention relates generally to automated cutting and/or scoring (hereinafter collectively “cutting”) of substrates bearing pre-printed graphics, registration marks, and optional so-called encoded-into-print instructions, e.g., barcoded instructions, and more specifically to dynamically detecting the registration marks for use in correcting the cutting plan for any substrate positional or alignment error on a cutting table station whereat cutting occurs, modifying the cutting plan according to any relevant encoded-into-print instructions, and to automatically cutting the substrate to achieve rapid and precise alignment of the cutting relative to the graphics.
Containers, cartons, boxes, placards and the like are commonly formed from a planar substrate such as cardboard, although other material may be used. The substrate is often printed with graphics, and may be scored and/or cut to form a not necessarily rectangular advertising medium, among other applications. It may be desired to cut (and/or score) the substrate around the perimeter of a pre-printed graphics, for example, which perimeter may be along a locus having varying direction, or along the dimensions of a box on which the pre-printed graphics should be positioned.
In some applications, the substrate may be cut first and then be printed with graphics. These various operations are sometimes referred to as short run cutting and scoring. Although short run operations can be carried out in various ways, it is always desired that cutting be in proper alignment with graphics, and that good speed and efficiency, collectively “throughput”, be maintained during the various processing operations. Note that by “short run production” is meant the production of a relative low volume.
In
Before cutting can occur, it is necessary that the just-loaded substrate be properly positioned and aligned at station 70, and on occasion manual intervention is required. Achieving and confirming proper positioning and alignment of the substrate before cutting occurs can be time consuming relative to overall throughput of system 10, and is relatively difficult to achieve.
At station 70, a sensor system 80 optically tries to locate and read bar encoded instructions 30. In some prior art application, bar encoded instructions can assist in more rapidly locating pre-printed registration marks 40 upon the sensor-facing surface of the substrate. Sensor system 80 may include a camera system and an associated computer system 90 to control operation of feed mechanism 60, and thus movement of substrate 20.
It is common in the prior art to use an edge of the just-loaded substrate as a reference to geometry printed on the substrate surface. However in practice, the edge of a substrate is not always sufficiently accurate to ensure that graphics are consistently located at a position a known distance from the substrate edge. Understandably if the graphics are not quite properly aligned relative to the substrate edge, when the substrate is cut, the cut-line might go through rather than around the graphics, or generate graphics that are not accurately positioned in the final folded box.
In a prior art system 10, unless the substrate can be perfectly aligned relative to the cutting table, it is necessary to modify the cutting plan based upon knowledge of such positional alignment error. Determination of such positional error and correction to the cutting plan occurs while substrate 20 is stationary at station 70. During this stationary period, feed mechanism 60 will also be stationary, for example responsive to a control signal output from computer system 90.
After computer system 90 determines position of the stationary substrate and makes any modifications to the cutting plan to compensate for positional misalignment of the substrate on the cutting table, cutting can commence at station 70. Sensor system 80 outputs a signal to computer system 90, which in turn will command cutting system 110 to cut (or score) the substrate, which is stationary at station 70. As noted, cutting can be responsive to encoded instructions present in bar codes 30 or may be responsive solely to instructions already present in computer system 90. As noted, it is desired that cutting occur in acceptable locations relative to the graphics and the desired cut and fold lines for the substrate.
Upon completion of the cutting operation at station 70, system 10 perhaps under control of computer system 90 re-starts feed mechanism 60, and the cut substrate, denoted 20′ in
What is needed is a computerized method and system to enable substrates pre-printed with graphics, reference alignment marks, and encoded-into-print instructions bar encoded data to be dynamically examined while being positioned on a cutting table region, and to have any required corrections made dynamically to a relevant cutting plan before cutting occurs. Such a method and system should require minimal operator intervention, and should exhibit substantially improved throughput. Further such system should lend itself to automated low volume sample production applications, in addition to full production run applications.
Aspects of the present invention provide such a computerized method and system, and substrates so cut.
Embodiments of the present invention promote throughput in a short run cutting and scoring system that transports and cuts substrates that have been simultaneously pre-printed with graphics, at least first and second registration marks, and optionally, encoded-into-print instructions that tell how the substrate is to be cut and/or scored by the system. In one embodiment, the invention includes a cutting table region whereon substrate cutting occurs, and preferably includes an in-stack region whereon substrates are stacked prior to being moved onto the cutting table region, and preferably includes an out-stack region whereon cut substrates are stacked for removal. The embodiment preferably includes a loadframe that transports substrates one at a time from the top of the in-stack, across the cutting table, and to the out-stack region. Loadframe transport velocity preferably is dynamic in that a high velocity is used to transport the substrate until the first registration mark is detected by the sensor system. Thereafter a lower loadframe velocity profile is used to ensure detection of the second registration mark with acceptable positional accuracy.
The system preferably further includes at least one sensor system that detects presence of the first and second registration marks. The detected registration mark positions are used by a computer system to correct the cutting plan for the substrate for any errors in positioning the substrate on the cutting table region. Optional encoded-into-print instructions may be read by the same sensor system or by a second sensor system for use in modifying the cutting plan for the substrate. Nominal offsets of the registration marks from the adjacent edge of the substrate will be known a priori, as will offset between the registration marks and a perimeter bounding the overall region to be cut and/or scored on the substrate. The overall x-axis dimension of the bounding box can be determined. Preferably four loadframe x-axis positions are defined: a zero-position as a substrate is picked-up from the in-stack, a first position corresponding to detection of the first registration mark (corresponding to x-axis distance from zero-position to the first registration mark), a second position corresponding to detection of the second registration mark (corresponding to x-axis distance between zero-position and the second registration mark), and a third position when the substrate is fully on the cutting table (which position information is used to calculate exact offset for the cutting and/or scoring to be carried out). The cutting table station defines a frame of reference definable by orthogonal x-and y-axes that intersect at an edge of the region. The mechanism that actually cuts the substrate uses this frame of reference.
Encoded loadframe positional information is coupled to a computer system that preferably controls the overall system including the loadframe and cutting table sensor. The computer system can calculate any required registration mark position offsets to modify reference points, as needed, to carry out the cutting and/or scoring task at hand. Similarly any required rotational positional offset for the substrate can be detected and corrected before cutting and/or scoring. The nominal cutting plan for the substrate to be cut includes a locus of coordinate (x,y) points on a two-dimensional cutting plane. The computer system uses the offset data to alter, as needed, these coordinates to correct for positional and/or rotational error. Subject to possible modification by data read from any optional encoded-into-print instructions, the corrected or updated cutting plan is then used by the computer system to control a cutting head. Since the graphics, registration marks, and optional encoded-into-print instructions were preferably simultaneously pre-printed on the substrate, good positional and rotational alignment between the graphics and the cutting line results.
Other features and advantages of embodiments of the present invention will appear from the following description in which preferred embodiments have been set forth in detail, in conjunction with the accompanying drawings.
As will now be described, aspects of the present invention promote throughput and high performance in a short run cutting and scoring system by optically reading registration marks on a substrate sheet while the substrate is being moved and loaded from an in-stack onto the cutting table station. Since register marks are pre-printed simultaneously with graphics (and with optional encoded-into-print instructions), the registration marks are precisely positioned relative to the graphics. Location of the registration marks may be rapidly sensed while the substrate sheet is being moved onto the cutting table station. Sensing the registration mark locations allows correcting cutting plan coordinates for any error in positional alignment including rotational offset of the substrate on the cutting table station. The cutting plan is thus adjusted to precisely accommodate the graphics on the substrate. Data read from optional encoded-into-print instructions permits altering the corrected cutting plan to accommodate a particular substrate, and/or to make adjustments from a standard template cutting plan. In an alternate embodiment, the encoded-into-print instructions include the actual cutting plan rather than variations from a prototype cutting plan. Implementation is flexible, and may be based upon existing and proven technology, for example the Kongsberg Digital Converting Machine (DCM) technology, available from Esko-Graphics located in Gent, Belgium.
Associated with lift table 220 is a lift table operator's panel 240 with controls to allow human supervision, if needed, of the stack lifting operation. An overall system 200 operator's control panel 250 and front-end computer system 260 are typically, but not necessarily, disposed near the lift table operator's panel 240. (Details of an exemplary front-end computer system 260 are shown in
After each successive top-most substrate 20-U is moved horizontally along the x-axis (in
Transport of uppermost substrate 20-U from in-stack region 210, onto and then off of cutting table station 230, and to out-stack region 300 will now be described. A traverse member 280 preferably is moved over the top region of the in-stack sufficiently to enable loadframe 290 to grip the front (right-most) edge of upper-most substrate, denoted 20-U. In one embodiment, loadframe 290 includes vacuum or suction cups (best seen in
In one embodiment, cutting table station 230 includes at least one base frame 310, each base frame preferably covered with a plastic cover 320. Cutting table station 230 includes a cutting table top surface 330 per se, and a preferably vacuum-based system 340 to hold down material (e.g., substrate 20-U) firmly against surface 330.
In practice, an uppermost substrate sheet 20-U preferably is automatically transported by loadframe 290 from the top of in-stack region 210 onto cutting table station 230 where vacuum-based system 340 secures the moving substrate against table surface 330. As substrate 20-U is being transported across surface 330, cutting table sensor system 350 examines the upper (or lower) surface of substrate 20-U for pre-printed registration marks 360, 360′, 360″ and preferably for any optional encoded-into-print instructions 370, 370′. The location, number of, and type of marks and data depicted in
As described later herein with respect to
At this juncture, substrate 20-U is securely on the surface 330 of cutting table station 230, and relevant corrections for the position of the substrate relative to the x-axis, y-axis reference frame of the cutting table station have been accounted for within the cutting plan, using sensor-acquired registration mark data. Also optional instructions 370, 370′ will also have been read into computer system 260 (or equivalent system) and will be input to make relevant modification to the cutting plan, or, in an alternate embodiment, the plan itself.
Within system 200, a tool head mechanism 380 includes a knife tip that projects controllably into the substrate. The knife tip portion of mechanism 380 extends only partially into the substrate for scoring, but extends completely through for substrate cutting. Mostly, scoring is carried out by a separate tool equipped with a score wheel. Movement of the knife tip to trace the locus of desired scoring and/or cutting lines (cut-line) in or through substrate 20-U preferably occurs under control of computer system 260. As such, movement of mechanism 380 can be horizontally in the (x,y) plane along y-axis carriage 390, as well as vertically upward and downward (along the z-axis). In one embodiment; the x-axis, y-axis frame of reference for cutting table surface 330 defines the frame of reference for tool head mechanism 380. (In the embodiment of
Preferably after substrate cutting or scoring is complete, the tip of the knife is permitted to move or drop downward along the z-axis onto a measuring pad 400 to ensure that the knife blade is still intact. This check of knife blade integrity can be carried out within a relatively short time period, e.g., a second or so.
In the embodiment shown, after tool head mechanism and associated knife tip 380 have completed cutting and/or scoring substrate 20-U, loadframe 290 moves the thus-processed substrate onto out-stack region 300. Preferably the out-stack region is disposed on a lift table system 410. An overhead sensor system 420 detects when a newly processed substrate sheet has been added to the top of the stack of substrates in out-stack region 300, and outputs a signal when such event is sensed. This sensor output signal then causes lift table system 410 to decrement in elevation a vertical distance ΔZ that approximates the substrate thickness, for example under control of computer system 260. Preferably out-stack region 300 is disposed such that processed substrate sheets are properly stacked, a feature that simplifies subsequent stripping operations.
In one embodiment, an out-stack door 430 is disposed adjacent region 300. Preferably when door 430 is opened, the lift table system 410 moves downward in elevation to permit pallet removal and transportation (not shown) of the processed substrates. Preferably when door 430 is closed, the lift table system 410 moves vertically upward to the correct height. Such vertical movement may, but need not be, under control of computer system 260.
Preferably a safety fence 440 is installed around system 200 to protect nearby personnel from the automated, rapidly functioning system, with safety fence doors 450 provided for operator access, as needed.
As noted, the above-described embodiment of the present invention makes use of registration marks 360 and any optional encoded-into-print instructions 370 to dynamically correct, as needed, and optionally alter the cut plan for the substrate at hand, or in an alternate embodiment, to read the cutting plan itself. It is advantageous to at least pre-print registration marks 360 simultaneously with graphics 375 to ensure that the geometric relationship between these marks and the graphics on the substrate is known. Precise location of optional barcodes or other format encoded-into-print instructions is less critical, but it may be convenient to also print such instructions 370 simultaneously with graphics 375 and registration marks 360. The encoded-into-print instructions 370 may be printed on surfaces of the substrate that will not be readily visible when the carton, box, or other structure that will result from the processed substrate is formed.
Having briefly described how system 200 can function to accurately score and/or cut a substrate relative to graphics printed on the substrate, a description will now be given as to an exemplary method by which a graphics artist can lay out the carton or box or other structure to be formed from the finished substrate. A typical end use of a substrate exiting out-stack 300 in system 200 might be a three-dimensional box or carton.
For ease of depiction, substrate 20 is shown in
As shown by
After the process shown in
Referring now to
It is understood that graphics 375 may be printed anywhere, even everywhere, on substrate 20. However for ease of illustration, only a simple graphics “AbCdEf” printed in one location is shown. As noted, one problem in the prior art is ensuring that when substrate 20 is cut and/or scored, that the printed graphics appear in good registration on the box, carton, or other object to be fabricated from the processed substrate. If optional encoded-into-print instruction 370 is printed, printing can be on a region of the box or carton that will not be visible to the end-user. For example instructions 370 can be printed on a bottom-facing portion of the three-dimensional box or carton, or on a portion that will be over-covered with a flap or panel of the three-dimensional box or carton. As noted, it is advantageous that at least registration marks 360′, 360″ and graphics 375 be simultaneously pre-printed to ensure good printing alignment, and optional instructions 370 may also be printed at the same time.
According to an embodiment of the present invention, it suffices for that two registration marks 360′, 360″ be printed on substrate 20 for use in correcting the cutting plan for positional error when the substrate is transported onto cutting table station surface 330. Turning now to
In
It is useful at this juncture to describe an exemplary computer system 260 used in one embodiment of the present invention to enter offset values Sx, Sy, Rx and Ry. Referring to
Typically the user of front-end computer system 260 can use one or more input devices such as a mouse, a trackball, a joystick, a digitizer tablet, or a computer keyboard to control system 200. For example, in one embodiment offset values Sx, Sy, Rx, and Ry preferably are entered into system 260 and maintained from a graphical user interface (GUI) dialog presented on monitor 560, which is coupled to computer system 510. Referring to
Referring briefly to the embodiment shown in
In one embodiment, program 550 includes a so-called wizard set of instructions that display on monitor 560 a command inviting the human operator to “obtain camera position” and to input such data into computer system 210. Preferably each time the position of camera system 350 is changed, the wizard will display the “obtain camera position” instructions to prompt the operator to input coordinate information to the system.
A single camera or equivalent sensor 350 can suffice to locate pre-printed registration marks 360 on a substrate 20. Also needed is information regarding movement of loadframe 290 to acquire at least first and second images from camera 350 in positions that properly represent detected locations of registration marks 360′, 360″.
Using image data acquired from sensor 350, computer system 260 (or equivalent) can execute a software program, perhaps program 550, to calculate proper cutting plan coordinate offsets (Sx, Sy, Rx, Ry) including any required adjustment for rotational position of substrate 20-U on surface 330. Once coordinate correction has been made by computer system 510 to the cutting plan to account for precisely how substrate 20-U lies upon surface 330, mechanism 380 can commence cutting the substrate. Since graphics 275 will preferably have been pre-printed simultaneously with registration marks 360′, 360″, the cut line will be precisely aligned with the graphics on the substrate.
In one embodiment, graphics 375, registration marks 360 and any encoded-into-print instructions 370 are printed on the upper surface of substrate 20-U, and the registration marks and instructions are sensed from above the substrate. In this embodiment, cutting is carried out from the lower surface of the substrate, although top-side cutting could instead be used.
As noted, in one embodiment, loadframe 290 position is feedback, for example via encoder 570 (see
In plan view
In
Loadframe 290 continues to transport substrate 20-U along the x-axis and in
In
In one embodiment, loadframe 290 can transport substrates along the x-axis at a high speed. In this embodiment, cutting table sensor system 350 is a camera operable whose shutter is adequate to acquire an image of first registration mark 360′ (see
Thus loadframe 290 preferably has a dynamic transport velocity. The velocity can be relatively rapid as sensor system 350 acquires an image of first registration mark 360′, but transport velocity should then be reduced to ensure accurate acquisition of an image of the second registration mark 360″. It will be appreciated that various velocity profiles may be programmed into system 200 to promote high-speed transport velocity while ensuring adequate accuracy of the image acquired for the second registration mark. For example if the X-dimension size is known by system 200 to be large, then the relatively rapid transport velocity can be maintained for a longer time between registration mark 360′ and the vicinity of registration mark 360″.
It will be appreciated that the window frame of cutting station camera sensor system 350 should encompass the size of registration mark 360′ or 360″. This requirement follows from the window frame size determining the maximum allowable error in positioning substrate 20-U atop cutting table station 230. In practice, the ΔT thickness of various types of substrates 20 may vary from perhaps 1 mm or so to at least 20 mm, and thus the focal length of cutting station sensor system 350 must encompass the foreseeable ranges of substrate thickness.
Preferably LCU 600 further outputs a TPU DO signal as input to a control unit 620 that synchronously controls shutter operation of camera sensor 630 within sensor system 350. As shown in
In summary it is seen that aspects of the present invention provide a high performance, automated short run cutting and scoring system. System performance is enhanced at least in part due to a dynamic loadframe velocity that can maintain high system throughput while ensuring acceptably good alignment mark position measurement accuracy. Rapidly acquired images of the first and second registration marks enable dynamic correction to the substrate cutting plan to account for the actual position of the substrate on the cutting table station. The amended cutting plan can also take into account any option encoded-into-print instructions. Since the graphics and at least the first and second registration marks will preferably have been pre-printed simultaneously, aspects′ of the present invention can cut with good precision and alignment relative to the graphics printed on the substrate surface.
Modifications and variations may be made to the disclosed embodiments without departing from the subject and spirit of the invention as defined by the following claims.
