AUTOMATIC METHOD AND DEVICE FOR CUTTING SUBSTRATES HAVING PRINTED IMAGES

Abstract

The invention relates to a method for cutting substrates with printed images in an automatic cutting device provided with means for correcting alignment errors based on the detection of longitudinal and transverse cutting marks. The longitudinal cutting marks (LM) are provided with a discontinuity (N) arranged upstream of each transverse cutting mark (TM) with respect to a feeding direction (F) of a substrate (S) and spaced therefrom by a predefined known measure (d). The automatic cutting device has a first optical unit configured to detect the transverse cutting marks (TM) and a second optical unit configured to detect the discontinuities (N) in the longitudinal cutting mark (LM). Since the velocity of the substrate is known, the control system activates the first optical unit when the transverse cutting mark (TM) actually passed underneath it.

Claims

1. A method for cutting substrates comprising printed images by way of an automatic cutting device provided with means for the correction of alignment errors, said method comprising the steps of: i) Printing a plurality of images on a substrate; ii) Printing a longitudinal cutting mark close to an edge of said substrate and parallel to edges of said images in a longitudinal or feeding direction and a plurality of transverse cutting marks perpendicular to said longitudinal cutting mark, said transverse cutting marks being arranged between consecutive images printed on said substrate; iii) Providing an automatic cutting device having a first optical unit configured for the detection of said transverse cutting marks; and iv) Feeding the substrate into said automatic cutting device; said longitudinal cutting mark is printed such that it has a discontinuity arranged upstream of each transverse cutting mark with respect to said feeding direction, said discontinuity being spaced from the respective transverse cutting mark by a predefined known measure; the automatic cutting device is provided with a second optical unit configured for the detection of said discontinuities in the longitudinal cutting mark; and a control system of the automatic cutting device is configured such that, when the second optical unit detects the discontinuities of the longitudinal cutting mark, the first optical unit is selectively activated for the detection of transverse cut marks printed on the substrate.

2. The cutting method according to claim 1, wherein the discontinuities of the longitudinal cutting mark are indentations.

3. The cutting method according to claim 1, wherein the second optical unit is configured to detect the discontinuities of the longitudinal cutting mark as well as to monitor the latter along the feeding direction and the correction of alignment errors of the substrate.

4. An automatic device for cutting substrates comprising printed images, said device comprising: i) one or more longitudinal cutting units configured to allow cutting of a substrate in a feeding direction; ii) a transverse cutting unit configured to allow cutting of said substrate in a transverse direction perpendicular to said feeding direction; iii) correction means for the correction of alignment errors of a substrate, wherein said correction means comprise a first optical unit arranged in said transverse direction and configured for the detection of transverse cutting marks printed on said substrate; and iv) a control system to which said first optical unit is operatively connected; further comprising a second optical unit that is operatively connected to said control system and is provided with two detection points, said second optical unit being arranged at one end of said automatic device in the transverse direction in such a way that, in use, said two detection points are arranged opposite each other with respect to a longitudinal cutting mark printed along an edge of the substrate fed in the feeding direction; and said control system is configured to activate the first optical unit selectively on the basis of signals indicative of discontinuities in said longitudinal cutting mark received from said second optical unit.

5. The automatic device according to claim 4, further comprising a third optical unit arranged at one end of said automatic device in the transverse direction and configured for monitoring the longitudinal cutting mark.

6. The automatic device according to claim 5, wherein the third optical unit is arranged close to the second optical unit.

7. The automatic device according to claim 4, wherein the second optical unit is configured for both the detection of the discontinuities of the longitudinal cutting mark and its monitoring in the feeding direction, as well as for the correction of alignment errors of the substrate.

Description

[0021] Further advantages and features of the present invention will become clear to those skilled in the art from the following detailed and non-limiting description of embodiments thereof with reference to the accompanying drawings wherein:

[0022] FIG. 1 is a perspective view showing an automatic cutting device according to the invention;

[0023] FIG. 2 shows a detail II of FIG. 1;

[0024] FIG. 3 is a top plan view schematically showing a portion of a substrate having two printed images and related cutting marks when the substrate passes through the automatic cutting device.

[0025] Referring to FIGS. 1 and 2, an automatic cutting device according to the invention for the cutting of substrates having printed images is generally indicated by reference numeral 100.

[0026] The device 100 includes a frame 110, for example a frame movable on wheels, comprising in a known manner a pair of uprights 111, 112 supporting a plane (not shown) intended to receive a substrate S having a plurality of printed images with the related cutting marks. A plurality of drag rollers (not shown) are also mounted on the frame 110 so as to allow to move the substrate S in a longitudinal or feeding direction between an inlet and outlet of the cutting device 100. The longitudinal or feeding direction is schematically indicated by an arrow F.

[0027] The cutting device 100 further comprises one or more longitudinal cutting units 120 configured to cut the substrate S in the feeding direction F and at least one transverse cutting unit 130 configured to cut the substrate S in a transverse direction T perpendicular to the feeding direction F.

[0028] The longitudinal cutting units 120 are restrained to a bar 113 of the frame 110 extending between the uprights 111, 112 in the transverse direction T. The position of the longitudinal cutting units 120 along the bar 113 in the transverse direction T can be modified manually or automatically, depending on the number of images printed on substrate S and on their layout. The transverse cutting unit 130 is movable along a guide 114 of the frame 110 extending between the uprights 111, 112 in the transverse direction T parallel to the bar 113. The transverse cutting unit 130 may e.g. be driven by a motor through a transmission belt.

[0029] The cutting device 100 further comprises means for correcting alignment errors of the substrate S relative to the feeding direction F and the transverse direction T along which the longitudinal cutting units 120 and the transverse cutting unit 130 operate. The correcting means include optical units, such as reflective optical cells, that are operably connected to a control system (not shown) of the device 100 comprising a microprocessor provided with a suitable control program. It is known that the correction of errors is based on the detection of longitudinal and transverse cutting marks printed on the substrate along the edges of the images.

[0030] In the embodiment shown in the drawings, the device 100 comprises a first optical unit 140, for example consisting of two reflective optical cells 141, 142 which may be associated with the guide 114 along which the transverse cutting unit 130 is moved. The first optical unit 140 is e.g. arranged in the middle of the guide 114 and the two reflective optical cells 141, 142 are spaced apart in transverse direction T so as to allow to detect alignment errors of the substrate relative to the transverse cutting marks printed thereon.

[0031] According to the invention, the cutting device 100 further comprises a second optical unit 150 operably connected to the control system and cooperating with the first optical unit 140 so as to send a confirmation of the actual passage of a transverse cutting mark to the control system.

[0032] The second optical unit 150, e.g. in the form of a linear CCD sensor or an equivalent sensor, comprises two reading points 151, 152 that are mutually spaced apart in the transverse direction T, and is arranged close to one of uprights of the frame, e.g. the upright 112, so that the two reading points 151, 152 are positioned opposite to each other with respect to a longitudinal cutting mark printed on the substrate S that proceeds in the feeding direction F.

[0033] FIG. 3 schematically shows a substrate S passing through the automatic cutting device 100 in the feeding direction F. A plurality of images IM1, IM2, etc. are printed on the substrate S consecutively in the feeding direction F. Transverse cutting marks TM, e.g. consisting of a pair of parallel black bands, are printed between consecutive images. A longitudinal cutting mark LM is printed close to an edge of the substrate S and extends parallel to the images IM1, IM2 in the feeding direction F.

[0034] According to the invention, the longitudinal cutting mark LM comprises a discontinuity, for example in the form of an indentation N, an interruption or the like, located upstream of each transverse cutting mark TM with respect to the feeding direction F and spaced therefrom by a predefined known measure d, for example comprised between 150 mm and 200 mm. This measure is an input given to the control system of the automatic cutting device 100.

[0035] Since the velocity of the substrate S in the feeding direction F is known, detection of the discontinuity N in the longitudinal cutting mark LM by the second optical unit 150 allows the control system to know precisely when the transverse cutting marks TM following the discontinuity will pass under the first optical unit 140 configured to detect them. This allows to avoid detection errors and therefore errors when correcting the position of the substrate S. The activation of the first optical unit 140 by the control system is selectively performed upon detection of the discontinuity in the longitudinal cutting mark LM. In other words, detection of the discontinuity in the longitudinal cutting mark LM predicts arrival of the transverse cutting marks TM.

[0036] According to an embodiment of the invention, the device 100 may comprise a third optical unit (not shown) restrained to the frame 110 close to one of the uprights, e.g. the upright 112, and configured to detect alignment errors of the substrate S with reference to the longitudinal cutting mark LM printed thereon. The third optical unit may advantageously be arranged close to the second optical unit 150, thus forming a single reading block for the longitudinal cutting mark LM.

[0037] According to an alternative embodiment of the invention, the second optical unit 150 may be configured for detecting the discontinuity N in the longitudinal cutting mark

[0038] LM preceding the transverse cutting TM, as well as for monitoring the longitudinal cutting mark LM, i.e. to control alignment of the substrate S.

[0039] The invention has herein been disclosed with reference to preferred embodiments thereof. It will be appreciated that there may be further embodiments relating to the same inventive idea, as defined by the scope of protection of the claims set forth below.