EP3693177B1 - Device and method for printing a print substrate - Google Patents

Description

The invention relates to a device and a method for printing on a print substrate.

background

When printing a material in a printing device or a printing system, the material can be provided as a continuous material on a roll. Alternatively, it can be provided that individual sheets are fed to the printing device one after the other in order to print the sheets individually. When printing continuous material, the continuous material can be separated after printing in order to obtain individual printed sheets.

The document DE 10 2016 102 565 A1 discloses a method and apparatus for producing a singulated sheet for a printing device. In the method, various sheet materials are made available as continuous material in magazine or buffer devices, with a transport path to a material switch, in which the transport paths converge, being arranged downstream of the magazine devices on the output side. Transport devices are provided which are each assigned to one of the transport paths and set up to transport the different sheet materials from the magazine device at least to the material switch. Control signals are received in the transport devices which determine a material selection corresponding to a print job for a selected one of the sheet materials. The transport devices are controlled according to the control signals in such a way that the selected sheet material is transported to the material switch and, in the material switch, moves from the transport path into a feed path into which the transport paths open. The selected sheet material is transported by means of the transport devices via the feed path from the material diverter to a separating device. A single sheet for subsequent printing is produced in the separating device by separating the single sheet from the selected sheet material.

In the document DE 10 2016 102 566 A1 describes a method and a device for printing a single sheet.

In the document DE 10 2014 104 662 A1 discloses a device for digital multipass multicolor printing on an unrolled web of material. The device has each a separately driven unwinding device and a winding device with associated dancer systems as unwinding and winding buffer stores, deflection rollers and a printer unit with a multi-color print head that can be moved across a printing table and the width of the material web, as well as a drive control. A separately driven feed roller is arranged in front of the printing table in the transport direction, which controls material removal from and material addition to the upstream and downstream dancer systems and the clocked feed of the material by a fraction of the print head length, with the fraction corresponding to the number of passes.

The document U.S. 2013/257963 A1 describes a method for controlling the transport of a print medium in an inkjet printer and the inkjet printer.

In the document U.S. 2011/261131 A1 describes an apparatus for handling a print substrate in a printer.

The document EP 2 384 897 A1 describes an inkjet printer having a printing plate which supports a printing medium, a printing means consisting of a carriage, an inkjet head and the like for performing printing on the printing medium supported by the printing plate, a medium feeding device which carries a feeding shaft around which the printing medium is wound in an elongated sheet form and in which the feed shaft is rotatable to feed out the print medium toward the platen, and a media winding device which has the same shape as the media feed device and supports a winding shaft for winding up the print medium and in which the winding shaft is rotatable to wind up the print media that has been fed out from the media feeding device and printed on by the printing device. The media feeding device and the media winding device are arranged bilaterally with respect to the printing plate in a feeding direction of the printing medium so as to be symmetrical in a side view.

The document JP H06 106895 A relates to a tension mechanism in a paper roll feeder in which a tension rod is inserted into the slack portion of paper fed from a roll. Both end parts of the rod are held freely rotatably by a slider. The slider is freely guided and supported by guide rails to move vertically. A pinion provided in the tie rod meshes with a rack.

In the document U.S. 2017/165986 A1 discloses a transport device in a printing facility in which an upstream drive roller transports an elongate medium. An upstream tension sensor detects the tension of the media. A downstream capstan transports the media. A downstream tension sensor detects the tension of the media at a position between the upstream and downstream drive rollers. A controller controls the transport of the medium by operating the upstream drive roller based on a first difference that is a difference between a first detection value and a target value and operating the downstream drive roller based on a second difference that is a difference between a second detection value and target value, and when a certain condition is met, further operates the downstream drive roller with a setting value based on the first difference added to the second difference.

The document U.S. 2008/056788 A1 discloses an image pickup device which picks up an image on an image forming area of a strip-shaped flexible substrate stretched between a supply roller and a take-up roller.

To print continuous material, the continuous material must be transported through the printing device or the printing system, with the transport movement being coordinated with the printing process and transport under suitable conditions through the entire printing device or the entire printing system having to be ensured, particularly in the area for printing responsible components have to meet the requirements that result from the printing process itself.

Summary

The object of the invention is to specify a device and a method for printing on a print substrate with improved transport of a print substrate. In this case, in particular, the control of a web tension of the printing substrate should be made possible in the device.

A device and a method for printing a print substrate according to independent claims 1 and 12 are provided for the solution. Configurations are the subject of dependent subclaims.

According to one aspect, an apparatus for printing on a print substrate is provided. The device has a print head shuttle with at least one print head, which is set up to apply a printing medium to a print substrate to generate a print image, wherein the print substrate is a web material that can be displaced along a web path, and the print head shuttle is arranged on a first side of the print substrate is. A print table is positioned opposite the printhead shuttle on a second side of the print substrate. The printing table has a holding device which is set up to hold the printing substrate in such a way that a relative movement between the printing table and the printing substrate is prevented for printing. The device also has a first web tension measuring device, which is arranged along the web path in front of the printing table and is set up to generate first measurement data, which indicate a mechanical web tension of the print substrate at the first web tension measuring device, a first tensioning device, which is arranged along the web path in front of the printing table and is set up to set a mechanical web tension of the print substrate, a second web tension measuring device, which is arranged along the web path after the printing table and set up to generate second measurement data, which indicate a mechanical web tension of the print substrate at the second web tension measuring device, and a second tensioning device, which along the Web path is arranged after the printing table and set up to adjust a mechanical web tension of the print substrate, and a control device. The control device is set up to receive the first measurement data, to generate first control data based on the first measurement data and to control the first tensioning device in accordance with the first control data, such that the first tensioning device effects a first specified web tension of the printing substrate on the first tensioning device, and the second Receiving measurement data, generating second control data based on the second measurement data and driving the second clamping device according to the second control data, such that the second clamping device causes a second predetermined web tension of the printing substrate on the second clamping device.

According to a further aspect, a method for printing on a print substrate is provided. The method includes: applying a printing medium to a printing substrate, which is a web material displaceable along a web path, having at least one print head of a print head shuttle arranged on a first side of the print substrate for generating a print image; Holding the print substrate, with a holding device of a print table, which is arranged opposite the print head shuttle on a second side of the print substrate, such that a relative movement between the print table and the print substrate is prevented for printing; Generating first measurement data with a first web tension measuring device, which is arranged along the web path in front of the printing table, the first measurement data indicating a mechanical web tension of the printing substrate at the first web tension measuring device; receiving the first measurement data in a control device; generating first control data based on the first measurement data in the control device; Controlling a first tensioning device, which is arranged along the web path in front of the printing table and set up to change a mechanical web tension of the print substrate, according to the first control data, such that the first tensioning device causes a first predetermined web tension of the print substrate on the first tensioning device; Generating second measurement data with a second web tension measuring device, which is arranged along the web path after the printing table, the second measurement data indicating a mechanical web tension of the printing substrate at the second web tension measuring device; receiving the second measurement data in the control device; generating second control data based on the second measurement data in the control device; and controlling a second tensioning device, which is arranged along the web path behind the printing table and set up to change a mechanical web tension of the print substrate, according to the second control data, such that the second tensioning device effects a second predetermined web tension of the print substrate on the second tensioning device.

By arranging the print head shuttle on a side of the web material opposite the printing table, the print substrate can be printed in particular by means of the print head shuttle while it rests on the printing table and is held by the holding device.

The web material can be a foil material. The foil material can be a plastic foil material, for example made of polycarbonate (PC) or polyvinyl chloride (PVC). The web material can be a thin web material. The thin web material can have a material thickness of 100 μm or less. For example, the web material can have a thickness of 75 µm. The web material can be provided with a width which corresponds to a desired width of the printed image, possibly plus the necessary side margins. For example, the web material can be provided with a width of 300 mm to 600 mm. A storage device can be provided, from which the web material is fed to the printing process. For example, the device can comprise a supply roll on which the web material is rolled up and from which the web material is drawn during operation.

The control device can be set up to keep the web tension of the print substrate constant along the web path in front of the printing table and to keep the web tension of the print substrate constant along the web path behind the printing table during a printing process. In this way, constant printing conditions can be ensured, in which the web tension in front of the printing table and the web tension behind the printing table remain constant.

The control device can be set up to repeatedly receive first and second measurement data during a printing process and to generate first and second control data. For example, the control device can be set up to receive first and second measurement data at a specified frequency and to generate first and second control data in each case. In this way, a first and a second control circuit can be provided, with the first control circuit controlling the web tension in front of the printing table by repeatedly receiving first measurement data and generating first control data as a function thereof in order to set the web tension in front of the printing table, and with the second control circuit controlling the Regulates web tension behind the printing table by repeatedly receiving second measurement data and generating second control data as a function thereof in order to adjust the web tension behind the printing table.

In order to generate at least the first or the second control data, the control device can be set up to compare the first or the second measurement data with the first or the second specified web tension and to generate first or second control data that result in an activation that corresponds in level and direction to the comparison result the first or the second clamping device. Comparing the first or the second measurement data with the first or the second predetermined web tension can include determining a deviation between the first or the second measurement data and the first or the second predetermined web tension. It can be an amount of Deviation and a direction of the deviation are determined. The deviation can thus indicate the difference by which the mechanical web tension of the printing substrate at the first or the second web tension measuring device is above or below the first or the second specified web tension.

Control data can be generated from the deviation, which triggers the first or the second tensioning device, which is suitable for compensating for the deviation and thus aligning the web tension with the first or the second specified web tension. For example, an actuator of the first or the second tensioning device can be controlled in order to adjust the web tension to the first or second specified web tension.

Comparing the first or the second measurement data with the first or the second predetermined web tension can include establishing that the first or second measurement data corresponds to the first or the second predetermined web tension if the amount of the deviation is less than a predetermined threshold value, and that Determining that the first or the second measurement data does not correspond to the first or the second predetermined web tension if the magnitude of the deviation is greater than the predetermined threshold value. The generation of first or second control data, which lead to an activation of the first or the second clamping device corresponding in level and direction to the comparison result, can include generating first or second control data if it is determined that the first or the second measurement data of the first or do not correspond to the second predetermined web tension, and not to generate first or second control data if it is determined that the first or second measurement data corresponds to the first or the second predetermined web tension.

Comparing the first or second measurement data with the first or second specified web tension can include comparing at least one characteristic value of the first or second measurement data with the first or second specified web tension. For example, a statistical characteristic value of the first or the second measurement data can be compared with the first or the second specified web tension. The statistical parameter can be, for example, an average value, a minimum value or a maximum value. The characteristic value can be determined over a measurement period of the first or the second measurement data.

The comparison and generation of control data can be provided both for the first control data and the first specified web tension and for the second control data and the second specified web tension.

The first predetermined web tension and the second predetermined web tension may be the same. Alternatively, the first predetermined web tension and the second predetermined web tension can be different. For example, the first specified web tension and the second specified web tension can be adapted to a respective structure of the printing device in front of and behind the printing table.

At least the first tensioning device or the second tensioning device can be a tensioning roller, which is at least partially wrapped around by the printing substrate and which can be moved by means of a drive device along a direction of movement running transversely to an axis of rotation of the tensioning roller, such that a movement of the tensioning roller in a first direction lengthens the web path along the drive direction in order to increase the mechanical web tension of the print substrate and a movement of the tension roller in a second direction opposite to the first direction shortens the web path in order to reduce the mechanical web tension of the print substrate. The first and second tensioning devices may be idler pulleys. In particular, a tensioning roller can be a so-called dancer.

At least the first web tension measuring device or the second web tension measuring device can be a web tension measuring roller around which the printing substrate is at least partially wrapped, such that the web tension of the printing substrate causes a transverse force perpendicular to an axis of rotation of the web tension measuring roller, the web tension measuring roller having a force measuring device for measuring the transverse force. The first and the second web tension measuring device can be web tension measuring rollers. The force measuring device can measure a force on a bearing of the axis of rotation of the web tension measuring roller. For example, a force-measuring device can include strain gauges, which are attached to the bearing of the axis of rotation and record the force on the bearing of the axis of rotation.

For example, the first web tension measuring device and/or the second web tension measuring device can be a so-called sensor roller system, a so-called block force transducer system and/or a so-called flange force transducer system. At a sensor roller system, force transducers can be integrated into the roller body. A block force transducer system can be provided with force sensors and set up to receive a bearing of a roll on which a web tension is measured. A flange force transducer system can be set up to accommodate a roller bearing and can be formed with an inner ring on which force sensors are arranged.

The holding device can comprise a vacuum device which sucks the print substrate onto the printing table by means of a vacuum. The vacuum device can generate a negative pressure and be connected to the environment via channels with a supporting surface of the printing table, so that the printing substrate is sucked onto the supporting surface of the printing table by means of the negative pressure in order to hold the printing substrate. At least a portion of the printing table comprising the support surface may be of a porous material, with the channels connecting the vacuum device to the support surface being provided by the porosity of the material. The porosity of the material can be a defined porosity. Due to the defined porosity of the material, undefined, statistically evenly distributed channels can be provided, which lead to an even suction and holding of the print substrate on the support surface. Alternatively, the channels can be provided with a defined grid of holes, for example microholes.

The holding means may additionally include gripping means which grips the print substrate to hold it. For example, the gripping device can include clamps that clamp the print substrate between the printing table and the clamps and thus grasp and hold it.

The holding device is set up to hold the print substrate during a feed movement of the print substrate in such a way that a relative movement between the printing table and the print substrate is prevented during the feed movement.

The printing table can be set up to carry out a feed movement while the holding device holds the print substrate in such a way that the feed movement is transmitted to the print substrate. As a result, the printing table can bring about a feed movement of the printing substrate along the web path. Alternatively or additionally, one or more feed devices can be provided, which cause the print substrate to be fed along the web path. For example, the printing table can have a feed movement of the print substrate along the web path, with one or more additional feed devices supporting the feed movement of the print substrate.

For printing, the print head shuttle can be set up to carry out a movement in front of and counter to a module movement direction running transversely to the feed direction of the print substrate. The feed movement of the print substrate and the movement of the print head shuttle can provide a positioning of the print head shuttle over the print substrate, which enables a print image to be generated on the print substrate. Alternatively or additionally, the print head shuttle can be set up to carry out a movement in front of and counter to a parallel module movement direction running parallel to the feed direction of the print substrate.

The apparatus may include a rejector. The selection device can include a testing device, a packaging device and a document switch. The checking device can be formed with an image recording device and set up to record an image of the print image on the web material, to compare the recorded image of the print image on the web material with comparison image data, to determine the print image as a correct print image when based on the comparison of the print image on the web material with the comparison image data a match between the print image and the comparison image data is determined, and to determine the print image as an incorrect print image if, based on the comparison of the print image on the web material with the comparison image data, there is no match between the print image and the comparison image data is determined. The making-up device can be set up to make up the web material into individual sheets and the document switch can be set up to direct a made-up sheet onto one of a first transport path and a second transport path, a made-up sheet with a print image which is determined to be a correct print image was, is routed to the first transport path and a made-up sheet with a print image which was determined to be an incorrect print image is routed to the second transport path.

A waste device can be arranged along the second transport path, which destroys a made-up sheet with a printed image that was determined to be an incorrect printed image. As a result, a reuse of the made-up sheet with a print image that was determined to be an incorrect print image can be ruled out be. Alternatively or additionally, sensitive data can be made unrecognizable. For example, the spoilage device can be a cutting device that cuts the made-up sheet with a print image that was determined to be an incorrect print image. The cutter can cut the sheet into strips. Parameters of the cutting device can be adjustable. For example, a strip width of the cut strips can be adjustable. The destroyed sheet, for example the strips to which the sheet was cut, can be collected in a waste container. The second transport route can lead to the scrap container.

The configurations explained in connection with the device for printing on a print substrate can be provided accordingly in the method for printing on a print substrate.

Description of exemplary embodiments

• Fig. 1 eine schematische Übersicht einer Druckvorrichtung zum Bedrucken eines Drucksubstrats;
• Fig. 2 eine schematische Übersicht einer Anordnung eines Drucktischs und eines Drucckopfshuttles in einer Druckvorrichtung;
• Fig. 3 eine schematische Übersicht weiterer Ausgestaltungsoptionen einer Druckvorrichtung; und
• Fig. 4 eine schematische Übersicht einer weiteren Druckvorrichtung zum Bedrucken eines Drucksubstrats.

Further exemplary embodiments are explained in more detail below with reference to drawings. Here show:

• 1 a schematic overview of a printing device for printing a print substrate;
• 2 a schematic overview of an arrangement of a printing table and a print head shuttle in a printing device;
• 3 a schematic overview of further configuration options of a printing device; and
• 4 a schematic overview of a further printing device for printing a printing substrate.

The Fig.1 shows a printing device for printing a printing substrate. The print substrate is a web material 1 on a roll 2 which serves as a storage device for the web material 1 . The web material 1 can be a plastic film. In one example, the web material 1 is a polycarbonate film with a thickness of 75 μm and a width of 600 mm. In a further example, the web material can consist of a different material, for example PVC, have a greater or smaller thickness, for example 100 μm, and/or have a smaller or larger width, for example 300 mm.

The web material is moved in a feed direction 4 through the printing device by means of a printing table 3 . For this purpose, the printing table 3 can be moved in the feed direction 4 and counter to the feed direction 4 . The printing table 3 is designed as a coherent unit or at least moves as a unit in order to support a feed of the web material 1 that is uniform over the width of the web material 1 . The printing table 3 has a holding device by means of which the web material 1 is held. While the web material 1 is held on the printing table 3 by the holding device, the printing table moves in the feed direction 4 from a rear position to a front position and thus pulls the web material 1 from the roll 2 in the feed direction 4 through the printing device. The holding device then releases the web material 1 so that it is detached from the printing table 3 . The printing table 3 then moves against the feed direction 4 past the web material 1 from the front to the rear position and then makes contact with the web material 1 again by means of the holding device, whereupon the movement of the printing table 3 in the feed direction 4 is repeated. A discontinuous advancement of the web material 1 through the printing device is thus provided.

In further configurations, additional drive mechanisms can be provided, which support the movement of the web material 1 provided by means of the printing table 3 . For example, driven rollers, over which the web material 1 runs and which move the web material 1 in a supporting manner, can be arranged in front of and/or behind the printing table 3 along a path of the web material 1 . In particular, an assisting drive mechanism may be arranged along the path of the web material 1 behind the printing table 3 to assist movement of the web material 1 away from the printing table 3 .

A print head shuttle 5 is arranged on a side of the web material 1 opposite the printing table 3 . The print head shuttle 5 is arranged opposite the printing table 3 with respect to the web material 1 in such a way that the web material 1 runs between the printing table 3 and the print head shuttle 5, so that it can be printed by means of the print head shuttle 5 while it is lying on the printing table 3 and from the holding device is held. The printing table 3 moves the web material past the print head shuttle 5 in the feed direction 4 . During the movement of the web material, the print head shuttle 5 prints the web material 1.

During the movement through the printing device, the web material 1 runs over a plurality of deflection rollers 6, by means of which the web material 1 is deflected within the printing device. The web material also runs over web tension measuring rollers 7, by means of which a web tension of the web material 1 is measured. Like in the 1 shown, a first web tension measuring roller 7a is arranged along the web path of the web material 1 in front of the printing table. The first web tension measuring roller 7a thus measures the web tension of the web material 1 in front of the printing table 3. By holding the web material 1 by means of the holding device on the printing table 3, a web tension of the web material 1 can occur along the web path of the web material 1 behind the printing table 3, which from the Web tension before the printing table 3 is independent. For this reason, a second web tension measuring roller 7b is arranged along the web path of the web material 1 behind the printing table. The second web tension measuring roller 7b thus measures the web tension of the web material 1 behind the printing table 3. The web tension of the web material 1 causes a respective force on the axes of the web tension measuring rollers 7a, 7b. The respective force on the axis of the web tension measuring rollers 7a, 7b is measured by means of a respective sensor device 8a, 8b of the web tension measuring rollers 7a, 7b. The respective sensor device 8a, 8b of the first 7a and the second 7b web tension measuring roller generates first or second measurement data which indicate the respective web tension of the web material 1 on the first web tension measuring roller 7a or on the second web tension measuring roller 7b.

Furthermore, the web material runs over so-called dancers 9. These are rollers which are movably arranged in order to adjust the tension of the web material 1. Like in the 1 a first dancer 9a can be seen along the path of the web material 1 in front of the printing table. In the example shown, the first dancer 9a can be moved up and down, with a downward movement of the first dancer 9a leading to an increase in the tension of the web material 1 and an upward movement of the first dancer 9a leading to a reduction in the tension of the web material 1 leads. The web tension of the web material 1 in front of the printing table 3 can thus be adjusted by means of the first dancer 9a.

A second dancer 9b is arranged along the path of the web material 1 behind the printing table. The second dancer 9b can also be moved up and down in the example shown, with a downward movement of the second dancer 9b leading to an increase in the tension of the web material 1 and a movement of the second dancer 9b upward leads to a reduction in the tension of the web material 1. The web tension of the web material 1 behind the printing table 3 can thus be adjusted by means of the second dancer 9b, which is independent of the web tension in front of the printing table 3 at least while the web material 1 is being held by the holding device on the printing table 3.

A control device 10 is connected to the web tension measuring rollers 7a, 7b and the dancers 9a, 9b (not shown) and is set up to receive the first and the second measurement data from the web tension measuring rollers 7a, 7b. In the control device 10, the first measurement data are compared with a first predetermined web tension. The first specified web tension specifies a desired web tension of the web material 1 along the web path of the web material 1 in front of the printing table. The control device 10 generates first control data corresponding to the comparison result, which are transmitted to the first dancer 9a and lead to a movement of the first dancer 9a. For example, the first control data indicate a small downward movement of the first dancer 9a if the comparison shows that the web tension of the web material on the first web tension measuring roller 7a deviates downwards by a small difference from the first specified web tension and the first control data indicates a larger one Movement of the first dancer 9a upwards when the comparison shows that the web tension of the web material on the first web tension measuring roller 7a deviates by a greater difference upwards from the first predetermined web tension.

The control device 10 is also set up to compare the second measurement data with a second specified web tension. The second predetermined web tension specifies a desired web tension of the web material 1 along the web path of the web material 1 behind the printing table. The control device 10 generates second control data corresponding to the comparison result, which are transmitted to the second dancer 9b and lead to a movement of the second dancer 9b. For example, as explained above with regard to the first dancer 9a, the second control data indicates a small movement of the second dancer 9b downwards if the comparison shows that the web tension of the web material on the second web tension measuring roller 7b has fallen by a small difference downwards from the second predetermined one Web tension deviates and the second control data indicate a greater upward movement of the second dancer 9b if the comparison shows that the web tension of the web material on the second web tension measuring roller 7b deviates upwards by a greater difference from the second predetermined web tension.

The web tensions upstream and downstream of the printing table 3 can be continuously monitored by repeatedly receiving first and second measurement data and generating corresponding first and second control data. As a result, the web tension in the printing device can be regulated along the web path of the web material 1 both in front of and behind the printing table 3 . For example, the first and the second specified web tension can be the same and the web tension of the web material 1 can be regulated both in front of and behind the printing table 3 in such a way that the same web tension of the web material 1 is achieved in front of and behind the printing table 3 within a predetermined permissible deviation.

The 2 shows an arrangement of a printing table 3 in a printing device, on which a web material 1 is arranged. The web material 1 is fed during a movement of the printing table 3 in a feed direction 4 (from the plane of the drawing in Fig 2 held out) by means of a holding device on the printing table 3, so that the web material 1 is moved along the feed direction 4 through the printing device. In the representation of 2 the holding device is provided with a vacuum device 11 . The vacuum device 11 generates a negative pressure. Here, the vacuum device 11 is connected via channels 12 to a support surface 13 of the printing table 3 with the environment. The web material 1 lies on the support surface 13 of the printing table 3 . To hold the web material 1, the vacuum device 11 generates a negative pressure during the movement of the printing table 3 in the feed direction 4, so that the web material is sucked onto the support surface 13 via the channels 12 and is thus held on the printing table 3.

In order to ensure that the web material 1 is held evenly on the support surface 13 , openings in the channels 12 are distributed over the entire support surface 13 . In the example of 2 For this purpose, the bearing surface 13 consists of a porous material with a defined porosity, which is connected to the vacuum device 11 . The porosity of the material of the bearing surface 13 provides undefined channels 12 which, due to the defined porosity, result in the web material 1 being sucked in and held uniformly on the bearing surface 13 . In alternative configurations, the channels 12 can be provided, for example, with a defined grid of bores, for example micro-bores, in order to ensure that the web material 1 is sucked in and held uniformly on the support surface 13 . Apart from the openings of the channels 12 in the support surface 13 or the porosity of the material, the support surface 13 of the printing table 3 is designed as a continuous surface. Interruptions in the bearing surface 13 can be provided. However, it is advantageous if the printing table 13 forms a unit and thus the supporting surface 13 is also moved as a coherent unit.

As a further alternative, the holding device may not be provided as a vacuum device 11 . For example, the holding device can be provided by means of one or more grippers which grip the web material 1 and hold it on the support surface 13 of the printing table 3 .

During the movement of the web material 1 on the printing table 3 past the print head shuttle 5, the print head shuttle 5 prints the web material 1 with a printing medium. The print head shuttle has one or more print heads 14 for this purpose. In the representation of 2 the print head shuttle 5 has two print heads 14a, 14b. A print head 14 can comprise a nozzle or a row of nozzles with a plurality of nozzles arranged in a row. The pressure medium can be ejected dropwise through the nozzles. For example, one print head 14 can be used for each desired color or material to be applied.

The print heads 14 are selectively controlled in order to selectively apply printing medium to the web material 1 and thus to generate a desired print image on the web material. In this case, the print head shuttle 5 moves back and forth transversely to the feed direction 4 of the web material 1 , so that the print heads 14 move over the web material 1 . The movement of the printing table 3 along the feed direction 4 thus results in a relative movement of the web material 1 to the print heads 14 in a first printing direction, and the movement of the print head shuttle 5 transversely to the feed direction 4 results in a relative movement of the web material 1 to the print heads 14 in a second Printing direction provided, which is transverse to the first printing direction. By selectively controlling the movement of the printing table 3, the movement of the print head shuttle 5 and the ejection of the printing medium from the print heads 14, a desired print image is thus applied to the web material 1.

Depending on the web material 1 used and the printing medium used, it can be advantageous to bring the web material 1 to a specific temperature for printing. For this purpose, the printing table 3 according to the 2 a heater 15 on. By means of the heating device 15, the support surface 13 of the printing table 3 to a predetermined temperature brought. As a result, the web material 1 arranged on the support surface 13 is heated to a printing temperature for printing.

The print head shuttle 5 also has a smoothing device. In the representations of figures 1 and 2 the smoothing device is a brush 16 which extends along a longitudinal direction which runs parallel to the feed direction 4 . The brush 16 as a functional part of the smoothing device is thus elongated in the longitudinal direction, parallel to the feed direction. It therefore has a greater extent in the longitudinal direction than in other directions. The smoothing device can thus have a smoothing effect transversely to the feed direction 4 when moving over the web material 1 . The brush 16 is as in the 2 shown, based on the direction of movement of the print head shuttle 5 arranged laterally on the print head shuttle 5. The brush 16 is movable up and down relative to the printhead shuttle 5 between first and second positions. In the first position, the brush 16 comes into contact with the support surface 13 so that the brush 16 sweeps across the web material 1 arranged on the support surface 13 of the printing table 3 when the module 5 moves transversely to the feed direction 4 . In the second position, the brush 16 is arranged above the printing table 3 in such a way that the brush 16 does not touch either the printing table 3 or the web material 1 when the print head shuttle 5 moves.

During a printing process, while the printing table 3 is in the rear position, a connection is formed between the web material 1 and the support surface 13 by means of the vacuum device 11 . The according to 2 While the printhead shuttle 5 is in a first module position in which the printhead shuttle 5 and the brush 16 are arranged to the right of the printing table 3, the brush 16 arranged on the left side of the printhead shuttle 5 is brought into the first position. During a subsequent first movement of the print head shuttle 5 over the printing table 3 and the web material 1, the brush 16 sweeps over the web material 1 and thus smoothes out wrinkles and/or bubbles that have formed in the web material 1 during the formation of contact between the bearing surface 13 and the web material 1 and/or during the heating of the web material 1 by means of the heating device 15.

After the brush 16 has been moved across the entire width of the web material 1, the brush 16 is brought to the second position. Thus, during subsequent movements of the print head shuttle 5, during the movement of the printing table 3 from the rear to the front position, the brush 16 does not come into contact with the web material 1. After release of the web material 1 from the printing table 3 and the movement of the printing table 3 from the front to the rear position, a connection is formed again between the web material 1 and the support surface 13 and the brush 16 is moved to the first position. Thus, during the first subsequent movement of the print head shuttle 5 over the web material 1, the web material is smoothed by the brush 16 after each contact is made with the bearing surface 13 of the printing table 3. FIG.

The length of the brush 16 corresponds at least to the length of the support surface 13 of the printing table 3 . Here, as in the 1 recognizable, the length of the brush 16 can be greater than a length of the print head shuttle 5, which can be shorter than the length of the contact surface 13. This ensures that the web material 1 is smoothed by the brush 16 over the entire length on which a contact is made to the support surface 13 of the printing table.

Optionally, a capping station 17 can be provided, which prevents the print heads 14 from drying out. When the printing device is not in use, the print head shuttle 5 is moved into a position in which the print heads 14 are shielded from the environment by the capping station 17 and the print heads 14 are thus prevented from drying out due to evaporation of solvent in the printing medium. Furthermore, a pressure medium tank 18 can optionally be provided for cleaning and/or preparing the print heads 14 for a printing process. The printhead shuttle can be moved to a position in which the printheads 14 are located above the fluid container 18. Pressure medium can then be ejected from the print heads 14 into the pressure medium containers 18 in order to free the print heads 14 of contamination and/or residual pressure medium and/or to remove air from the pressure medium transport paths in the print heads 14 .

Like in the 1 drying devices 19a, 19b are shown along the path of the web material 1 behind the printing table 3 and in the area of the second web tension measuring roller 7b and the second dancer 9b. The printing medium on the web material 1 is dried by means of the drying devices 19a, 19b. For example, the drying devices 19a, 19b can be hot air blowers and/or UV radiators. Different drying devices 19a, 19b can be provided.

The 3 shows further configuration options of a printing device. This can, for example, the printing device from the 1 be. Alternatively, the design options according to the 3 in a printing device other than the printing device according to the 1 be provided. A printed image testing device 20 is arranged along the movement path of the web material 1 behind the second dancer 9b and the drying devices 19a, 19b. The print image checking device 20 has an image recording device 21 which is set up to record an image of the print image on the web material 1 . In the print image checking device 20, the recorded image of the print image on the web material 1 is compared with comparison image data, which can be, for example, print job data of a print job for printing the print image. If a match between the print image and the comparison image data is determined on the basis of the comparison of the print image on the web material 1 with the comparison image data, the print image is determined as a correct print image. If, based on the comparison of the print image on the web material 1 with the comparison image data, no match is established between the print image and the comparison image data, the print image is determined as an incorrect print image.

A match between the print image and the comparison image data is established when the recorded image of the print image on the web material 1 corresponds to the comparison image data within predetermined limits. If the recorded image of the print image on the web material 1 does not correspond to the comparison image data within the predetermined limits, no match between the print image and the comparison image data is determined. The comparison of the recorded image with the comparison image data can be, for example, a pixel comparison and/or a comparison of characteristic values of the recorded image, for example a contrast value.

A roller drive 22 is arranged behind the testing device 21 to support the movement of the web material 1 along the movement path of the web material 1 . A further dancer 9c for controlling the web tension of the web material 1 is arranged behind the roller drive 22 . The additional dancer 9c can, for example, be controlled by the control device 10 in accordance with the second sensor data. Alternatively, a further web tension measuring roller can be provided, which generates third measurement data, by means of which the control device 10 controls the further dancer 9c.

Along the path of movement of the web material 1 behind the testing device 21 and the additional dancer 9c, there is a finishing device 23 which is set up to finish the web material 1 into individual sheets. For example, the web material 1 can be fed to the finishing device 23 and by means of a cutting device 24 of the assembly device 23 are cut to a predetermined sheet size in order to assemble the web material 1 into individual sheets. The individual sheets are then directed in a document switch 25 to different transport paths 26a, 26b. A transport path 26a leads into a document container 27. Another transport path 26b leads into a reject container 28. Sheets that carry a print image that has been determined as the correct print image are determined as document sheets 29 and are guided by the document switch 25 onto the transport path 26a, the leads into the document container 27. Sheets that carry a print image that was determined to be an incorrect print image are determined as waste sheets 30 and are guided by the document switch 25 onto the transport path 26b, which leads into the waste container 28. In this way, it is possible to sort out printed sheets which have errors in the printed image. The printed image of a waste sheet 30 can then be printed again.

Optionally, a bad marking device 31 can be provided, which is arranged along the movement path of the web material 1 behind the testing device 21 and in front of the finishing device 23 . The bad marking device 31 is set up to provide a print image which was determined as an incorrect print image with a mark which characterizes the print image as an incorrect print image. For example, the bad marking device 31 can include a print head for this purpose.

Provision can be made for the print image to include a plurality of individual print images. In this case, each individual print image can be determined as a correct individual print image or an incorrect individual print image, and the bad marking device 31 can be set up to provide each individual print image determined as an incorrect individual print image with a mark, which identifies the individual print image as an incorrect individual print image. In this case, the document switch 25 can be omitted and all the individual sheets can be fed to the document container 27 via the transport path 26a.

Alternatively, the document switch 25 can be provided and set up to transport printed sheets with a print image that includes a number of individual print images marked as incorrect individual print images that exceeds a predetermined maximum number of incorrect individual print images via the transport path 26b feed reject bin 28 and feed other sheets to the document bin 27 via the transport path 26a.

The 4 shows a further printing device for printing a printing substrate. In the configuration according to 4 the printing device has two dancers 9a, 9b, but no third dancer. In this exemplary embodiment, a roll unwinding module 40 includes the roll 2, the first web tension measuring roller 7a with the sensor device 8a, the first dancer 9a and the associated deflection rollers 6. According to the embodiment shown, a printing module 41 includes the printing table 3, the print head shuttle 5 and the brush 16. A drying module 42 includes the second web tension measuring roller 7b with the sensor device 8b, the second dancer 9b, the drying devices 19a, 19b and the associated deflection rollers 6. An image processing module 43 includes the print image checking device with the image recording device 21 and optionally the bad marking device 31 Drying module 42 and the image processing module 43 can be combined to form a drying and image processing module. According to the in the 4 In the embodiment shown, a finishing module 44 comprises the roller drive 22, the finishing device 23 with the cutting device 24, the document switch 25, the transport paths 26a, 26b, the document container 27 and the scrap container 28.

The features disclosed in the above description, the claims and the drawing can be important both individually and in any combination for the realization of the various embodiments.

Reference List

1

web material

2

role

3

printing table

4

feed direction

5

printhead shuttle

6

pulleys

7a, 7b

web tension measuring roller

8a, 8b

sensor device

9a, 9b, 9c

dancer

10

control device

11

vacuum device

12

channels

13

bearing surface

14a, 14b

printheads

15

heating device

16

brush

17

capping station

18

pressure fluid tank

19a, 19b

drying device

20

testing device

21

image pickup device

22

roller drive

23

packaging facility

24

cutting device

25

document switch

26a, 26b

transport routes

27

document container

28

reject bin

29

document sheet

30

waste sheet

31

Bad marking device

40

roll unwind module

41

pressure module

42

drying module

43

image processing module

44

assembly module

Claims (12)

1. A device for printing on a print substrate (1), comprising

   - a print head shuttle (5) comprising at least one print head (14a, 14b) which is configured, for producing a print image, to apply a printing agent to a print substrate (1), wherein the print substrate (1) is a web material displaceable along a web path, and the print head shuttle (5) is arranged on a first side of the print substrate (1);

   - a print table (3) which is arranged opposite the print head shuttle (5) on a second side of the print substrate (1), having a holding device (11) which is configured to hold the print substrate (1) during a feed movement of the print substrate (1), in such a manner that for printing, a relative movement between the print table (3) and the print substrate (1) during the feed movement is prevented;

   - a first web tension measuring device (7a, 8a), which is arranged along the web path upstream of the print table (3) and is configured to produce first measuring data which indicate a mechanical web tension of the print substrate (1) at the first web tension measuring device;

   - a first tensioning device (9a) which is arranged along the web path upstream of the print table (3) and is configured to set a mechanical web tension of the print substrate (1);

   - a second web tension measuring device (7b, 8b), which is arranged along the web path downstream of the print table (3) and is configured to produce second measuring data which indicate a mechanical web tension of the print substrate (1) at the second web tension measuring device;

   - a second tensioning device (9b) which is arranged along the web path downstream of the print table (3) and is configured to set a mechanical web tension of the print substrate (1); and

   - a control device (10) which is configured

   - to receive the first measuring data, to produce first control data based on the first measuring data and to actuate the first tensioning device (9a) in accordance with the first control data, in such a manner that the first tensioning device (9a) brings about a first predefined web tension of the print substrate (1) at the first tensioning device (9a); and

   - to receive the second measuring data, to generate second control data based on the second measuring data and to actuate the second tensioning device (9b) in accordance with the second control data, in such a manner that the second tensioning device brings about a second predefined web tension of the print substrate (1) at the second tensioning device (9b).
2. The device according to claim 1, characterized in that the device is configured for a web material which is a film material.
3. The device according to claim 1 or 2, characterized in that the control device (10) is configured, during a print run, to keep the web tension of the print substrate (1) constant in time along the web path upstream of the print table (3) and to keep the web tension of the print substrate (1) constant in time along the web path downstream of the print table (3).
4. The device according to at least one of the preceding claims, characterized in that the control device (10) is configured to receive first and second measuring data and to generate first and second control data repeatedly during a print run.
5. The device according to at least one of the preceding claims, characterized in that the control device is configured

   - for producing at least the first or the second control data, to compare the first or the second measuring data with the first or the second predefined web tension and

   - to produce first or second control data which lead to an actuation of the first or the second tensioning device corresponding to the result of the comparison in terms of amount and direction.
6. The device according to at least one of the preceding claims, characterized in that the first predefined web tension and the second predefined web tension are the same.
7. The device according to at least one of the preceding claims, characterized in that at least the first tensioning device (9a) or the second tensioning device (9b) is a tensioning roller which is entwined at least in part by the print substrate (1) and which can be moved by means of a drive device along a movement direction running orthogonally to a rotational axis of the tensioning roller, in such a manner that a movement of the tensioning roller in a first direction along the drive direction extends the web path, in order to increase the mechanical web tension of the print substrate (1), and a movement of the tensioning roller in a second direction running counter to the first direction along the drive direction shortens the web path, in order to reduce the mechanical web tension of the print substrate (1).
8. The device according to at least one of the preceding claims, characterized in that at least the first web tension measuring device (7a, 8a) or the second web tension measuring device (7b, 8b) is a web tension measuring roller, which is entwied by the print substrate (1) at least in part, in such a manner that the web tension of the print substrate (1) brings about a transverse force orthogonal to a rotational axis of the web tension measuring roller, wherein the web tension measuring roller has a force measuring device for measuring the transverse force.
9. The device according to at least one of the preceding claims, characterized in that the holding device (11) comprises a vacuum device which draws the print substrate (1) onto the print table (3) by means of a vacuum.
10. The device according to at least one of the preceding claims, characterized in that the print table (3) is configured to perform a feed movement, while the holding device (11) holds the print substrate (1) in such a manner that the feed movement is transferred to the print substrate (1).
11. The device according to at least one of the preceding claims, characterized by a sorting device, comprising:

    - a test device (20) with an image recording device (21) which is configured

    - to record an image of the print image on the web material,

    - to compare the recorded image of the print image on the web material with comparative image data,

    - to determine that the print image is a correct print image if comparing the print image on the web material with the comparative image data leads to a match between the print image and the comparative image data being established, and

    - to determine the print image is an incorrect print image if comparing the print image on the web material with the comparative image data does not lead to a match between the print image and the comparative image data being established;

    - a tailoring device (23) which is configured to tailor the web material into individual sheets; and

    - a document deflector (25) which is configured to conduct a tailored sheet onto one of a first transport path (26a) and a second transport path (26b), wherein

    - a tailored sheet with a print image which has been determined as a correct print image is conducted onto the first transport path (26a) and

    - a tailored sheet with a print image which has been determined as an incorrect print image is conducted onto the second transport path (26b).
12. A method for printing a print substrate (1) comprising:

    - application of a printing agent onto a print substrate (1), which is a web material displaceable along a web path, using at least one print head of a print head shuttle (5), which is arranged on a first side of the print substrate (1), in order to produce a print image;

    - holding the print substrate (1) during a feed movement of said print substrate (1), using a holding device (11) of a print table (3) which is arranged opposite the print head shuttle (5) on a second side of the print substrate (1), in such a manner that, for printing, a relative movement between the print table (3) and the print substrate (1) during the feed movement is prevented;

    - generation of first measuring data with a first web tension measuring device (7a, 8a) which is arranged along the web path upstream of the print table (3), wherein the first measuring data indicate a mechanical web tension of the print substrate (1) at the first web tension measuring device (7a, 8a);

    - receiving of the first measuring data in a control device (10);

    - generation of first control data based on the first measuring data in the control device (10);

    - actuation of a first tensioning device (9a) which is arranged along the web path upstream of the print table (3) and is configured to change a mechanical web tension of the print substrate (1), in accordance with the first control data, in such a manner that the first tensioning device (9a) brings about a first predetermined web tension of the print substrate (1) at the first tensioning device (9a);

    - generation of second measuring data with a second web tension measuring device (7b, 8b) which is arranged along the web path downstream of the print table (3), wherein the second measuring data indicate a mechanical web tension of the print substrate (1) at the second web tension measuring device (7b, 8b);

    - receiving of the second measuring data in the control device (10);

    - generation of second control data based on the second measuring data in the control device (10); and

    - actuation of a second tensioning device (9b) which is arranged along the web path downstream of the print table (3) and is configured to change a mechanical web tension of the print substrate (1) in accordance with the second control data, in such a manner that the second tensioning device (9b) brings about a second predefined web tension of the print substrate (1) at the second tensioning device (9b).

Images