Method for Automated Error Management in a Printing Machine

Abstract

The invention relates to a method for automated error management in a printing machine, in which a recurring print image is imprinted on a moving material web.

To improve automated error management for existing inspection systems, a method is provided in which an inspection of the moving material web is controlled by a control unit and a function switch, the function switch being switchable at least between a first function mode and a second function mode, and in which the print image is acquired by a first inspection unit in the first function mode and forwarded to the control unit, and in which the print image is acquired by a second inspection unit in the second function mode and forwarded to the control unit.

Claims

1. Method for automated error management in a printing machine, the method comprising: imprinting a recurring print image on a moving material web, controlling an inspection of the moving material web with a control unit and a function switch, the function switch being switchable between at least a first function mode and a second function mode, acquiring, by a first inspection unit in the first function mode, the print image and forwarding the print image to the control unit, and acquiring, by a second inspection unit in the second function mode, the print image and forwarding the print image to the control unit.

2. The method of claim 1, wherein the first inspection unit comprises a line scan camera for continuous inspection of print images.

3. The method of claim 1, wherein the second inspection unit comprises an area scan camera capable of zooming for inspecting specific areas of a print image.

4. The method of claim 1, wherein the first inspection unit comprises a first error recognition algorithm.

5. The method of claim 1, wherein the second inspection unit comprises a second error recognition algorithm.

Description

[0013] The attached drawings describe further details and advantages of the invention.

[0014] FIG. 1 shows an overall view of the printing machine according to the invention, using the example of a flexographic printing machine,

[0015] FIG. 2 shows a detail view of FIG. 1 including a line scan camera and a moving material web, and

[0016] FIG. 3 shows a detail view of FIG. 1. including an area scan camera capable of zooming and a moving material web.

[0017] FIG. 1 shows an overall view of the printing machine according to the invention, using the example of a flexographic printing machine 101 having a camera 102, a prepress phase 103, a control unit 104, and a control station 106. The control unit is installed at position 105 of the flexographic printing machine 101 and is shown separately for reasons of clarity.

[0018] The flexographic printing machine 101 is a so-called color impression machine and thus has a color impression drum 107 around which the eight color decks are installed in a satellite arrangement. Each of these color decks has a plate cylinder, an anilox mandrel and a doctor blade chamber, each mounted on machine-side anchorages. Color deck 108 is labeled with the described components as an example of these eight color decks.

[0019] To imprint the material web 109, it is pulled off the material roll 111 in the unwinding station 110 and guided over several deflection rollers to the nip roller 112. The nip roller 112 places the material web 109 on the color impression drum 107 for further transport so that the material web 109 is moved with register accuracy past the color decks and the between-color dryers not shown in detail.

[0020] Once the material web 109 has left the color impression drum 107, it is moved through a bridge dryer 113 for drying the ink and is then wound onto the material roll 115 in the rewinding station 114.

[0021] Camera 102 is designed to be operable both as a line scan camera and as an area scan camera capable of zooming by the control unit. Camera 102 is connected to the control unit 104 via cable 116 for operation. Alternatively, it is understood that two separate cameras may be provided in the form of a line scan camera and an area scan camera, it being feasible to operate both cameras either jointly or individually as desired.

[0022] The monitor of the control station 106 is designed as a touchscreen, enabling the operator to execute certain commands for operating the flexographic printing machine 101 directly on the monitor through menu navigation. Among other features, the menu navigation of the control station provides a function switch on the touchscreen, the function switch being switchable between at least a first function mode and a second function mode.

[0023] In the first function mode, the print image is acquired by a first inspection unit and forwarded to the control unit. Among other features, the first inspection unit comprises the camera 102, camera 102 being operated as a line scan camera in the first function mode. The first inspection unit also comprises an inspection system for continuous web inspection. Another common term for continuous web inspection is 100% inspection as the recurring print images on the moving material web are acquired 100%. The first inspection unit finally also comprises an inspection system for error recognition with a first error recognition algorithm. For this purpose, an initial print image 118 (composite file) is saved together with the color separations from the prepress phase 103 in the control unit 104, the prepress phase being connected to the control unit 104 via cable 117. In control unit 104, the initial print image 118 is then compared to the actual print image acquired by camera 102.

[0024] FIG. 2 shows a detail view of FIG. 1 with a line scan camera and a moving material web. Since the corresponding reference signs were transferred from FIG. 1, reference should be made to the description of FIG. 1. The representation of FIG. 2 corresponds to the first function mode so that camera 102 is operated as a line scan camera that continuously acquires the print image 201.

[0025] However, there may occasionally be areas in the print image that cannot be optimally inspected in the first function mode with the settings of the first inspection unit. These include, for example, areas in the image that contain specific spot colors, coatings, patterns, and the like. In order to optionally inspect these areas in the print image under different settings, the operator may use the function switch on the monitor of control station 106 to interrupt the first function mode and to briefly switch to the second function mode.

[0026] When the function switch is actuated, the control unit automatically executes all commands to switch to the second function mode.

[0027] FIG. 3 shows a detail view of FIG. 1 including an area scan camera capable of zooming and a moving material web. Since the corresponding reference signs were transferred from FIG. 1, reference should be made to the description of FIG. 1. The representation of FIG. 3 corresponds to the second function mode so that camera 102 is operated as an area scan camera capable of zooming.

[0028] In the second function mode, the print image is acquired by a second inspection unit and forwarded to the control unit. In addition to the area scan camera, the second inspection unit also comprises special settings that allow for optimal inspection of the aforementioned areas in the print image 301. This may include other illumination situations (e.g. light field instead of dark field) or the use of special software filters. The control unit saves the acquired images and keeps them available for subsequent offline inspection by the operator. Alternatively or additionally, the inspection may also be performed using a second error recognition algorithm.

[0029] Once a sufficient number of images has been acquired by the area scan camera, the control unit automatically switches back to the first function mode for continuous web inspection. Alternatively, it is understood that the operator may initiate the switch back to the first function mode.

TABLE-US-00001 List of reference signs 101 Flexographic printing machine 102 Camera 103 Pre-press phase 104 Control unit 105 Position of the flexographic printing machine 101 106 Control station 107 Color impression drum 108 Color deck 109 Material web 110 Unwinding station 111 Material roll 112 Nip roller 113 Bridge dryer 114 Rewinding station 115 Material roll 116 Cable 117 Cable 118 Initial print image 201 Print image 301 Print image