EP2974865B1 - Method for the localization of a fault on a printing substrate and device for carrying out said method - Google Patents

Description

The present invention relates to a method and a device for fault location on a printing substrate.

The invention lies in the technical field of quality management.

From the prior art is from the patent DE 102005001417 B4 a display and control device for controlling machines with a projection device for projecting an image on a projection surface, with which it is possible to simulate the effects of changes made to the operating device. For this purpose, the control computer of the machine calculates the probable effects of the changes made and projects the calculated image data onto an existing printing material. Its image content is known to the control computer, so that the visual overlay of projected data and image content of the printing material corresponds to a hypothetical image printed with the changes made. Such a device is useful for checking the performance of the inspection system. This gives the user feedback as to whether he can still rely on the inspection system by making a comparison as to whether the system has changed with respect to a previous time; eg with regard to image quality, computer performance, lens quality, contamination. However, what this device does not enable is an automatic quality inspection of already printed printed products. In addition, the device described is very complicated implement both hardware and software, since image data recorded and made changes must be simulated and projected.

For the automatic quality investigation is from the patent application DE 19516352 A1 a device for image inspection of the printed image of a product of a printing press, the device having an image detection device which provides actual image data from the product, which by means of a comparison circuit with target image data of a error-free subjects are compared. The errors detected during the described inspection are displayed on a monitor, whereby the recorded print image is subdivided into inspection areas and the inspection areas with detected defects are displayed on the monitor. A disadvantage of the disclosed device, however, is that no precise location of the detected errors is possible, since only the corresponding inspection area is marked on the monitor. In addition, no simultaneous analysis of the error location and the error itself is possible because only one piece of information can be meaningfully displayed on the monitor at the same time.

From the German godparent application DE 41 00 170 A1 In addition, a color mixer for visual and metrological quality control of printed sheets is known in which a printed sheet is scanned by a hand-held measuring device and wherein a mounted on the sheet at the desk projection device emits light rays over the entire sheet and wherein a photo sensor is mounted in the meter, which recognizes when it is struck by a light beam, whereby the current position information of the measuring device can be determined on the sheet.

From the German patent application DE 103 53 868 A1 In addition, a device for displaying certain data of a printing press on a printed sheet is known, wherein by means of a projection device which is positioned above the printed sheet, the data can be projected onto the printed sheet.

The European patent application EP 0 410 253 A2 on the other hand discloses a device for data acquisition, control and display of measured values in quality monitoring on a printing machine. In this case, the integration of workflows and to improve the quality of work and operation of the sheet is recorded with a video camera lying on a Abmusterungstisch. The data is stored in a memory for digital image data. At the Abmusterungstisch measuring devices for detecting quality data of the printed image are arranged and provided with markings. Parallel to the video camera, a light source is provided both for displaying data and as a guide device for the measuring devices. Between video camera and light source are one or more systems for Image evaluation, in particular for pattern recognition, provided that use the data of the memory for the image data. As measurement devices come colorimeters, register meters or hand-held scanners, ie. small format scanners, which are guided by hand on the surface to be scanned, in question

A possible alternative is therefore to shift the display of the fault location information from the monitor to an existing printed test sheet on which the fault location (s) are then displayed by means of projection. Particularly suitable for this type of projection are various forms of projection lasers, in particular laser pointers. These are known from the prior art in various performance classes and colors, as well as in general in a variety of designs.

The object of the present invention is thus to describe a device and a method for fault location, which facilitates the user finding fault locations on the sheet.

The inventive solution to this problem is a method having the features of main claim 1 and an apparatus having the features of claim 8.

• Durchführen eines Druckauftrages mit Inspektion der gedruckten Bögen
• Auflegen eines bedruckten Probebogens auf eine Ablagevorrichtung
• Markierung der, durch die Inspektion, gefundenen Druckfehler auf dem bedruckten Probebogen mittels Hervorhebung der Fehlerkoordinaten durch eine an oder in der Ablagevorrichtung befestigte Lichtquelle, wobei die Lichtquelle ein Laserpointer ist
• Anzeige der mittels der automatischen Inspektion gefundenen Fehlerdurch eine über oder an der Ablagevorrichtung angebrachte Anzeigevorrichtung.

It is a method for determining fault location on a printed sheet, which comprises the following steps.

• Performing a print job with inspection of the printed sheets
• Placing a printed test sheet on a storage device
• Marking the printing defects found on the printed sample sheet by the inspection by highlighting the error coordinates by a light source attached to or in the depositing device, the light source being a laser pointer
• Display of errors found by means of the automatic inspection by means of a display device mounted above or on the storage device.

The display of the errors found by the inspection on a display device mounted in the viewing and reading range to the depositing device and the fault location made possible by the method according to the invention supplement each other. The user needs information about the error itself as well as about the location of the error in order to assess the errors found.

For carrying out the method presented, a device for determining fault location on a printed sheet for carrying out a method according to claim 1 is also disclosed. The device consists of a display device, a storage device for a sheet, a control computer and at least one light source in the form of a laser pointer, which is attached to the storage device or integrated into this, that of the computer-controlled at least one light source, each location on the surface one of the depositing device aligned sheet is markable. In addition, the function of at least one light source is switched on and off by a foot switch attached to the storage device.

Advantageous and therefore preferred developments of the method will become apparent from the accompanying dependent claims and from the description with the accompanying drawings.

A preferred development is that the light source marks several fault locations by rapid clocking. For reasons of efficiency, it is appropriate for a light source to display several fault locations. This makes it possible to simultaneously display more errors than light sources are available.

A further preferred development is that a plurality of light sources for fault location display are attached to or in the storage device. The multiple light sources can also individually mark multiple fault locations. As a result, the number of errors to be displayed simultaneously by the system is enormous.

A preferred development of the inventive method is that the multiple light sources with different colors different errors and / or identify different degrees of severity of the errors. In interaction with each other, a division of tasks of the light sources by severity or by type of error is made possible by means of different light colors. Also, various projected geometric figures or a combination of the features mentioned are possible

A preferred development of the method according to the invention is that the sample sheet is aligned on the storage device on the basis of information from the printing press, such as print format, print start and center offset. If the device does not have automatic adaptation of the fault location projection to the location of the sample sheet, the user must manually align the sample sheet with information from the press, such as print size, print start, and center offset. The information can be made available to the user via the display device.

A further preferred development of the method is that a, attached to the storage device, camera determines the edges or the registration marks of the sample sheet based on information on the sample sheet and the one or more light sources are aligned according to the determined edges of the sample sheet. The automatic adaptation of the fault location projection to the position of the test sheet saves time because the user no longer has to manually align the test sheet.

A preferred development of the device according to the invention is that on the storage device an angle bar or a coordinate system for the alignment of the sheet is present. If neither an automatic adaptation to the position of the test sheet nor information from the printing press are available, a coordinate cross or an angle strip mounted on the depositing device allow the user to correctly align the sample sheet.

The method and functionally advantageous developments of the method will be described below with reference to the accompanying drawings with reference to at least one preferred embodiment described in more detail. In the drawings, corresponding elements are provided with the same reference numerals.

Fig. 1:

die Vorrichtung zur Fehlerortbestimmung auf einem Druckbogen

Fig. 2:

den Ablauf des Verfahrens der Fehlerortbestimmung auf einem Druckbogen

The drawings show:

Fig. 1:

the device for fault location on a sheet

Fig. 2:

the sequence of the method of fault location on a sheet

The device according to the invention consists in the main of a storage device on which a test sheet is to be stored, which contains image information, which are examined for errors during an image inspection. Above or next to the storage device one to several light sources are locked. Whether the light sources are firmly fixed and different radiation angles are possible by the design of the light sources, or whether light sources are fixed with a fixed beam angle movable, depends on the embodiment. The decisive factor is that the light sources can be controlled via a control computer in such a way that they can detect the entire area of the stored test sheet. In addition to the storage device, a display device is mounted, via which the image errors determined by the inspection are displayed.

In the preferred embodiment, as in FIG. 1 is shown, the device according to the invention is combined with the operating device of a printing press. The display device is identical to the display device of the control panel of the printing press. The storage device corresponds to the storage console of the operating device for the proofs. In this case, an angle bar and / or a coordinate system are mounted on the storage device so that the user a correct manual alignment of the sample sheet is possible. The light sources, which preferably consist of laser pointers, are on a holding device on the filing desk appropriate. They are attached to devices with controllable, movable electric motors, which are controlled by an external control computer or the control computer of the printing press. The individual laser pointers have different colors, so that with each color a different type of error and / or error severity can be displayed. Since the laser pointer, depending on the power class, emit dangerous radiation to the human eye, the device may only be used under the expert control of the user. To ensure this, a footswitch is attached to the bottom of the device that allows the user to turn the laser pointer function on and off.

The implementable with this device, the inventive method is in its preferred embodiment in FIG. 2 shown schematically. As part of the processing of a print job, a continuous inspection of the printed sheets is carried out. During or before the inspection, the user places a test sheet of the current print job on the storage device. The sample sheet is to be aligned correctly next. This can be done manually by the user on the basis of an existing on the filing angle bar or a coordinate system. In an alternative embodiment, the sheet is detected by a camera and the edges or registration marks of the sample sheet are determined based on information on the sample sheet. The laser pointers are then aligned by the control computer according to the determined edges or registration marks of the sample sheet. In a further alternative embodiment, the alignment is done on the basis of information from the printing press, such as print format, print start and center offset. If image or printing errors are then found by the inspection, these are displayed by the control computer of the printing press on the display device. This is preferably done in sections and if reasonably enlarged to give the user precise knowledge about the nature of the error. In addition, the control computer calculates the position information on the printed sheet of the error (s) found. With the knowledge of the nature and location of the errors found, the computer controls the laser pointer in such a way that they mark the location of the errors found on the sample sheet. The method disclosed in the preferred embodiment allows both the pure marking of the fault location on a fault-free Test sheet, as well as the use of the faulty test specimen, on which then the local errors are displayed. The first variant requires an accurate representation of the error found on the display device. The marking of the fault location is then only the classification of the error found in the image environment. The advantage of this variant is the quick processing of errors found by the user, since one and the same test sheet can be used for a wide variety of errors. The disadvantage, however, is that only the fault location is marked on the sample sheet. The error must be examined to assess the facts on the display device. On the other hand, the second variant involves the removal of the faulty sheet from the printing press, whereby the errors found on the device marked by the device are then also present in real terms. Here, the representation of the error on the display device is only supportive and not mandatory. An assessment of the errors found by the user is thus much easier for this, but the process takes more time. Which procedure is preferred is at the discretion of the user. Device and method allow the use of both variants.

Various types of errors and severity of errors are characterized by differently colored laser pointers. The assignment of colors and error types or severity levels is configurable and is communicated to the user via the display device. A distinction between different errors and degrees of severity can also be done by various geometric shapes, such as circles, rectangles, etc., for this purpose, the use of other light sources as laser pointer is more advantageous, such as certain LED arrays. If more errors are found in the scope of an examination than there are laser pointers, several cycles are covered by fast clocking, ie switching over several positions of a laser pointer. In addition, to preclude any danger to the eyes of nearby people, the user must, while he checked on the marked fault locations operate a footswitch, which activates the function of the laser pointer. If the user leaves the workstation, the laser pointers will not emit light due to the footswitch not operating.

LIST OF REFERENCE NUMBERS

1

angle bar

2

storage device

3

test sheet

4

light source

5

display device

6

footswitch

7

computer

8th

Error found

9

Location information of the sample sheet 10 Control panel

11

user

Claims (8)

1. Method for locating an error location on a print sheet comprising the steps of

   • carrying out a print job and inspecting the printed sheets

   • placing a sample print sheet on a deposit device

   • marking the print defects found in the inspection on the sample print sheet by highlighting the error coordinates by a light source arranged on or in the deposit device, the light source being a laser pointer

   • displaying the errors found in the automated inspection on a display device arranged above or on the deposit device.
2. Method according to claim 1,
   characterized in
   that the light source marks multiple error locations due to a short cycle.
3. Method recited in any one of the preceding claims,
   characterized in
   that multiple light sources for indicating error locations are arranged on or in the deposit device.
4. Method according to claim 3,
   characterized in
   that the multiple light sources indicate different errors and/or different error degrees in different colours.
5. Method according to any one of the preceding claims,
   characterized in
   that the sample sheet is aligned on the deposit device in accordance with information from the printing press such as print format, start of the print, centre offset.
6. Method according to any one of the preceding claims,
   characterized in
   that based on information on the sample sheet, a camera arranged on the deposit device detects the edges or the register marks of the sample sheet and that the one or more light sources are oriented in a way corresponding to the detected edges or register marks of the sample sheet.
7. Device for implementing a method for locating error locations on a print sheet according to claim 1, consisting of a display device, a deposit device for a sheet, a control unit and at least one light source,
   characterized in
   that the at least one light source is a laser pointer and is disposed on the deposit device or integrated into the latter in such a way that by means of the at least one light source, which is controlled by the control unit, every location on the surface of a sheet aligned on the deposit device is markable and that at least one foot switch is provided on the deposit device to switch the function of the at least one light source on and off.
8. Device according to claim 7,
   characterized in
   that an angle bar or a coordinate plane is provided on the deposit device to align the sheet.

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