EP3693175B1 - Device and method for printing a print substrate - Google Patents

Description

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

background

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

The document EN 10 2016 102 565 A1 discloses a method and a device for producing a separated sheet for a printing device. In the method, various sheet materials are provided 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, each of which is assigned to one of the transport paths and is set up to transport the various sheet materials from the magazine device at least to the material switch. The transport devices receive control signals that determine a material selection for a selected one of the sheet materials that corresponds to a print job. 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 it passes 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 switch to a separating device. In the separating device, a separated sheet is produced for subsequent printing by separating the separated sheet from the selected sheet material.

In the document EN 10 2016 102 566 A1 A method and a device for printing a single sheet are described.

The document US 2010/0271453 A1 describes a recording apparatus having a recording head for performing a recording operation by ejecting ink on a recording surface of a recording medium during movement, a transport section for transporting the recording medium along a transport path passing through a recording area in which the recording head performs the recording operation, a platen arranged in the recording area to support a surface opposite to the recording surface of the recording medium, and pressing elements arranged in the recording area and in contact with outer edge portions in a width direction of the recording surface of the recording medium. The pressing elements move to press the recording medium on an upstream side and on a downstream side of the recording head with a movement of the recording head.

The document EP 3 434 489 A1 discloses a liquid ejecting device having a holding portion for holding a medium, a first ejecting portion capable of ejecting a pretreatment liquid onto the medium held by the holding portion, a first holding portion for holding the first ejecting portion, and a smoothing portion provided at and between the first holding portion a smoothing position in contact with an ejection area onto which the pretreatment liquid is ejected, and a non-smoothing position in non-contact with the ejection area of the medium.

In the document US 2011/242210 A1 An ink jet recording device is described. The ink-jet recording apparatus includes an ink-jet head, a first carrier on which the ink-jet head is supported, a guide member, a moving mechanism that moves the first carrier along the guide member, a transport mechanism that moves a medium along a transport surface, and a second carrier which is mutually movable following a movement of the first carrier and is designed to be relatively movable to the first carrier in a direction perpendicular to the transport surface. The second carrier has a protection element that protects a spray surface from the medium and a regulating element that regulates movement of the second carrier in relation to a third direction.

In the document JP 2017-109364 A a printer with a paper guide unit and two paper sensors and a printing method are disclosed.

The document DE 690 25 124 T2 describes an inkjet printer, the document JP H05-162397 A a printer.

The document DE 43 21 177 A1 discloses a device for image inspection and color measurement on at least one printed product that was created in a printing press with at least one printing unit. The device consists of at least one image capture device, which supplies image data from the printed product, and a computing device, whereby the computing device, on the one hand, determines all image data of the printed product for the purpose of image inspection and, on the other hand, determines a measurement variable for a color assessment from the image data of at least one measuring point (pixel) of the printed product .

In the document DE 10 2010 060 408 A1 an arrangement for regulating the web tension of a printing material web in a printing device is described.

To print on a continuous material, the continuous material must be transported through the printing device or the printing system, whereby the transport movement must be coordinated with the printing process and transport must be ensured under suitable conditions through the entire printing device or the entire printing system, particularly in the area of the printing The responsible components must meet the requirements that arise from the printing process itself.

Summary

The object of the invention is to provide a device and a method for printing on a printing substrate with an improved provision of a printing substrate, in particular with regard to avoiding unevenness of the printing substrate.

To solve this, a device and a method for printing on a printing substrate according to independent claims 1 and 13 have been created. Refinements are the subject of the dependent subclaims.

According to one aspect, a device for printing a printing substrate is provided. The device has a print head shuttle with at least one print head, which is designed to apply a printing medium to a printing substrate in order to generate a print image, wherein the printing 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 printing substrate. A printing table with a support surface is arranged opposite the print head shuttle on a second side of the printing substrate. The printing table has a holding device that is designed 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 print head shuttle has a smoothing device which is configured to come into contact with the support surface of the printing table and to be moved over at least a portion of the support surface such that it sweeps over a printing substrate arranged on the support surface of the printing table in order to smooth it, wherein the smoothing device extends along a longitudinal direction which runs parallel to the feed direction.

According to a further aspect, a method for printing a printing substrate is provided. The method comprises: applying a printing medium to a printing substrate, which is a web material that can be displaced along a web path, with at least one print head of a print head shuttle, which is arranged on a first side of the printing substrate, for generating a print image; holding the printing substrate with a holding device of a printing table, which is arranged opposite the print head shuttle on a second side of the printing substrate, such that a relative movement between the printing table and the printing substrate is prevented for printing; and smoothing the web material arranged on a support surface of the printing table by means of a smoothing device, which strokes over the printing substrate arranged on the support surface of the printing table by coming into contact with the support surface of the printing table and over at least part of the support surface is moved, wherein the smoothing device extends along a longitudinal direction which runs parallel to the feed direction.

By arranging the print head shuttle on a side of the web material opposite the printing table, the printing 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 smoothing device, which strokes over the printing substrate by coming into contact with the support surface of the printing table and moving over the support surface, can eliminate unevenness such as wrinkles or bubbles. In this way, the printing process is optimized and the print image can be improved. Unevenness can arise in particular from the transport of the printing substrate designed as a web material, in particular the feed, but also from other factors that affect the resting of the printing substrate on the printing table. For example, heating the printing substrate by a heated printing table can lead to unevenness in the printing substrate, which can be eliminated by the smoothing device. It is understood that due to the thin design of the web material, the smoothing device comes into contact with the web material which is arranged on the support surface of the printing table when the smoothing device is set up to come into contact with the support surface. Therefore, the smoothing device comes into contact with the support surface of the printing table and comes into contact with the printing substrate, which may be arranged on the support surface.

According to the invention, the smoothing device extends along a longitudinal direction which runs parallel to the feed direction. Here, a functional part of the smoothing device is elongated in the longitudinal direction, i.e. has a greater extent in the longitudinal direction than in other directions. In particular, it can be provided that the smoothing device moves transversely, preferably perpendicular to the feed direction, over the support surface of the printing table. When the smoothing device is extended in the longitudinal direction, the smoothing device can have a smoothing effect when moving over the support surface of the printing table.

The smoothing device can be arranged on the print head shuttle in such a way that the smoothing device moves with the print head shuttle. The smoothing device is preferably arranged at the front of the print head shuttle with respect to a direction of movement of the print head shuttle. arranged, ie when the print head shuttle moves in the printing direction, the smoothing device smooths the printing substrate before it is printed on. In this way, the smoothing device does not have to be moved separately, but can simply be attached to the print head shuttle and moved with it. If the print head shuttle moves transversely to the feed direction of the printing substrate, the smoothing device also moves transversely to the feed direction.

In a preferred embodiment, the smoothing device is movable transversely to a direction of movement of the print head shuttle, preferably up and down relative to the print head shuttle, between a first and a second position. In the first position, the smoothing device can be in contact with the support surface of the printing table (or, as explained above, with the printing substrate arranged on the support surface of the printing table), so that the smoothing device strokes over the printing substrate arranged on the support surface of the printing table during a movement. Furthermore, the smoothing device can be arranged above the printing table in the second position in such a way that the smoothing device does not touch the printing substrate, preferably also the printing table, during a movement.

In particular, it can be provided that the smoothing device only passes over the printing substrate once before the first printing process. In order not to smear the printed image, the smoothing device can then be moved to the second position, in particular raised, so that it no longer touches the printing substrate, preferably also the printing table. Alternatively, it is also conceivable that the smoothing device is uncoupled from the print head shuttle after the printing substrate has been smoothed and remains on the opposite side while the print head shuttle moves back for the next printing process. The smoothing device can then later be brought back to the starting position on the print head shuttle for another printing process.

The smoothing device preferably has a length that corresponds to at least one length of the support surface of the printing table. The length of the smoothing device can be equal to or greater than one length of the print head shuttle. This ensures that the entire width of the printing substrate is swept over and smoothed. However, if necessary, it can also be provided to swept over only part of the printing substrate.

The smoothing device may comprise a brush or be formed by a brush. In particular, bristles of the brush can point in the direction of the support surface of the printing table and smooth the printing substrate on the printing table. In this way, a sufficiently strong, yet gentle contact pressure of the smoothing device on the printing substrate can be achieved. The printing substrate is not only pressed smooth, but unevenness is smoothed out. It is understood that the smoothing device can alternatively or additionally also have other suitable structures, such as a lip, for example a rubber lip or other plastic lip, a sponge or even rigid smoothing bodies, which can be rigid or flexible, soft or hard depending on the application. The smoothing device may possibly be spring-mounted in order to achieve the appropriate contact pressure.

The aforementioned holding device can be designed to hold the printing substrate during a feed movement of the printing substrate in such a way that a relative movement between the printing table and the printing substrate is prevented during the feed movement. The holding device can comprise a vacuum device which sucks the printing substrate onto the printing table by means of a negative pressure or vacuum. The vacuum device can be connected to the environment via channels with a support surface of the printing table, so that the printing substrate is sucked onto the support surface of the printing table by means of the negative pressure in order to hold the printing substrate. A printing substrate held on the support surface of the printing table by a suitable negative pressure can be easily smoothed out by the smoothing device described above, in particular in comparison to a clamped printing substrate.

For printing, the print head shuttle can be set up to carry out a movement in front of and against a shuttle movement direction that runs transversely to the feed direction of the printing 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 above the print substrate, which enables the creation of a print image on the print substrate. Alternatively or additionally, the print head shuttle can be set up to carry out a movement in front of and against a parallel shuttle movement direction that runs parallel to the feed direction of the printing substrate.

The web material may be a film material. The film material may be a plastic film material, for example made of polycarbonate (PC) or polyvinyl chloride (PVC). The web material may be a thin web material. The thin web material may have a material thickness of 100 µm or less. For example, the web material may 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 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 pulled during operation.

The device can further comprise a first web tension measuring device which is arranged along the web path in front of the printing table and is configured to generate first measurement data which indicate a mechanical web tension of the printing 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 configured to set a mechanical web tension of the printing substrate, a second web tension measuring device which is arranged along the web path after the printing table and is configured to generate second measurement data which indicate a mechanical web tension of the printing substrate at the second web tension measuring device, and a second tensioning device which is arranged along the web path after the printing table and is configured to set a mechanical web tension of the printing substrate, as well as a control device. The control device can be configured to receive the first measurement data, generate first control data based on the first measurement data and control the first clamping device in accordance with the first control data such that the first clamping device effects a first predetermined web tension of the printing substrate on the first clamping device, and to receive the second measurement data, generate second control data based on the second measurement data and control the second clamping device in accordance with the second control data such that the second clamping device effects a second predetermined web tension of the printing substrate on the second clamping device.

The control device can be configured to keep the web tension of the printing substrate constant along the web path in front of the printing table and to keep the web tension of the printing substrate constant along the web path behind the printing table during a printing process. Thus, consistent 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 device can comprise a sorting device. The sorting device can comprise a testing device, a processing device and a document switch. The testing device can be formed with an image recording device and be set up to record an image of the printed image on the web material, to compare the recorded image of the printed image on the web material with comparison image data, to determine the printed image as a correct printed image if a match between the printed image and the comparison image data is found based on the comparison of the printed image on the web material with the comparison image data, and to determine the printed image as an incorrect printed image if a match between the printed image and the comparison image data is found based on the comparison of the printed image on the web material with the comparison image data.

The assembly device can be set up to assemble the web material into individual sheets and the document switch can be set up to direct a assembled sheet onto one of a first transport path and a second transport path, wherein a assembled sheet with a printed image, which is determined to be a correct printed image was directed to the first transport path and a finished sheet with a print image that was determined to be an incorrect print image is directed to the second transport path.

A waste device can be arranged along the second transport path, which destroys a prepared sheet with a printed image that was determined to be an incorrect printed image. This makes it impossible to reuse the finished sheet with a print image that was determined to be an incorrect print image. Alternatively or additionally, sensitive data can be made unrecognizable. For example, the waste device can be a cutting device that cuts the finished sheet with a print image that has been determined to be an incorrect print image. The cutting device 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 into which the sheet was cut, can be collected in a reject container. The second transport route can lead to the reject container.

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

In the following, further embodiments are explained in more detail with reference to drawings. Here:

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

The Fig.1 shows a printing device for printing on a printing substrate. The printing 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 another material, for example PVC, have a larger or smaller thickness, for example 100 μm, and / or have a smaller or larger width, for example 300 mm.

The web material is moved through the printing device in a feed direction 4 by means of a printing table 3. For this purpose, the printing table 3 is movable in the feed direction 4 and against 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 uniform advance of the web material 1 across 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 means of 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 forms 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. This provides a discontinuous movement of the web material 1 through the printing device.

In further embodiments, additional drive mechanisms can be provided which support the movement of the web material 1 provided by the printing table 3. For example, driven rollers over which the web material 1 runs and which support the movement of the web material 1 can be arranged along a web path of the web material 1 in front of and/or behind the printing table 3. In particular, a supporting drive mechanism can be arranged along the web path of the web material 1 behind the printing table 3 in order to support a 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 print table 3. The print head shuttle 5 is arranged opposite the print table 3 with respect to the web material 1 in such a way that the web material 1 runs between the print table 3 and the print head shuttle 5 so that it can be printed on by means of the print head shuttle 5 while it rests on the print table 3 and is held by the holding device. The print table 3 moves the web material past the print head shuttle 5 in the feed direction 4. While the web material is moving, the print head shuttle 5 prints the web material 1.

When moving through the printing device, the web material 1 runs over several 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 web tension of the web material 1 is measured. Like in the Fig. 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 is from the Web tension in front of 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 and 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 arranged to be movable in order to adjust the tension of the web material 1. As shown in the Fig.1 A first dancer 9a can be seen arranged 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. The web tension of the web material 1 in front of the printing table 3 can thus be adjusted using 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 is also movable 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 leading 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 means of 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 second measurement data from the web tension measuring rollers 7a, 7b. In the control device 10, the first measurement data is compared with a first predetermined web tension. The first specified web tension indicates 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 is transmitted to the first dancer 9a and leads to a movement of the first dancer 9a. For example, the first control data indicates 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 predetermined web tension and the first control data indicates a larger one Movement of the first dancer 9a upwards if the comparison shows that the web tension of the web material on the first web tension measuring roller 7a deviates upwards by a larger difference from the first predetermined web tension.

The control device 10 is further set up to compare the second measurement data with a second predetermined web tension. The second predetermined web tension indicates 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 is transmitted to the second dancer 9b and leads to a movement of the second dancer 9b. As explained above with regard to the first dancer 9a, for example, the second control data indicates a small downward 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 is down by a small difference from the second predetermined one Web tension deviates and the second control data indicates a larger 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 larger difference from the second predetermined web tension.

The web tensions in front of and behind the printing table 3 can be continuously monitored by repeatedly receiving first and second measurement data and generating corresponding first and second control data. This can provide control of the web tension in the printing device, along the web path of the web material 1 both in front of and behind the printing table 3. For example, the first and second predetermined 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 Fig. 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 drawing plane of the Fig. 2 out) is held 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 illustration of the Fig. 2 the holding device is provided with a vacuum device 11. The vacuum device 11 generates a negative pressure. The vacuum device 11 is connected to the environment via channels 12 to a support surface 13 of the printing table 3. 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 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 the Fig. 2 For this purpose, the support surface 13 consists of a porous material with a defined porosity, which is connected to the vacuum device 11. Due to the porosity of the material of the support surface 13, undefined channels 12 are provided, which, due to the defined porosity, lead to a uniform suction and holding of the web material 1 on the support surface 13. In alternative embodiments, the channels 12 can be provided, for example, with a defined grid of holes, for example micro-holes, in order to ensure uniform suction and holding of the web material 1 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 support surface 13 can be provided. However, it is advantageous if the printing table 13 forms a unit and the support surface 13 is therefore 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.

While the web material 1 moves 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. For this purpose, the print head shuttle has one or more print heads 14. In the illustration of the Fig.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 several nozzles arranged in a row. The printing medium can be ejected drop by drop 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 produce a desired print image on the web material. 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 provides 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 provides a relative movement of the web material 1 to the print heads 14 in a second printing direction which runs transversely 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 may be advantageous to bring the web material 1 to a certain temperature for printing. For this purpose, the printing table 3 points according to the Fig. 2 a heating device 15. By means of the heating device 15, the support surface 13 of the printing table 3 is brought to a predetermined temperature. 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 the 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 therefore 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 when moving over the web material 1 transversely to the feed direction 4. The brush 16 is as in the Fig. 2 presented, related arranged laterally on the printhead shuttle 5 in the direction of movement of the printhead shuttle 5. The brush 16 is movable up and down relative to the printhead shuttle 5 between a first and a second position. In the first position, the brush 16 comes into contact with the support surface 13, so that when the printing head shuttle 5 moves transversely to the feed direction 4, the brush 16 strokes the web material 1 arranged on the support surface 13 of the printing table 3. 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 the Fig. 2 Brush 16 arranged on the left side of the print head shuttle 5 is brought into the first position while the print head shuttle 5 is in a first position, in which the print head shuttle 5 and the brush 16 are arranged to the right of the print table 3. During a subsequent first movement of the print head shuttle 5 over the printing table 3 and the web material 1, the brush 16 strokes over the web material 1 and thus smoothes wrinkles and / or bubbles that appear in the web material 1 during the formation of contact between the support surface 13 and the web material 1 and / or may have arisen 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 into the second position. 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 therefore does not come into contact with the web material 1. After the web material 1 is released from the printing table 3 and the printing table 3 is moved from the front to the rear position, a connection is again formed between the web material 1 and the support surface 13 and the brush 16 is moved to the first position. The web material is thus smoothed by the brush 16 after each contact is made with the support surface 13 of the printing table 3 during the first subsequent movement of the print head shuttle 5 over the web material 1.

The brush 16 has a length which corresponds at least to the length of the support surface 13 of the printing table 3. Here, as in the Fig. 1 As can be seen, the length of the brush 16 may be greater than a length of the print head shuttle 5, which may be shorter than the length of the support surface 13. This ensures that the web material 1 passes through the brush 16 is smoothed over the entire length on which contact is made with 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 printhead shuttle 5 is moved into a position in which the printheads 14 are shielded from the environment by the capping station 17 and thus the printheads 14 are prevented from drying out due to the evaporation of solvent in the printing medium. Furthermore, a pressure medium container 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 above the pressure medium container 18. Subsequently, pressure medium can be ejected from the print heads 14 into the pressure medium containers 18 in order to free the print heads 14 from contamination and/or pressure medium residues and/or to remove air from transport paths of the pressure medium in the print heads 14.

Like in the Fig.1 As shown, drying devices 19a, 19b are arranged 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 lamps. Different drying devices 19a, 19b can be provided.

The Fig. 3 shows further design options for a printing device. This can be done, for example, by the printing device Fig. 1 be. Alternatively, the design options can be according to Fig. 3 in a printing device other than the printing device according to the Fig. 1 be provided. A print 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 printed 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 based on the comparison of the print image on the web material 1 with the comparison image data, the print image is determined to be a correct print image. If based on the comparison of the If the print image on the web material 1 and the comparison image data do not match the print image and the comparison image data, the print image is determined to be an incorrect print image.

A match between the print image and the comparison image data is determined if 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 is determined between the print image and the comparison image data. 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.

To support the movement of the web material 1, a roller drive 22 is arranged along the path of movement of the web material 1 behind the testing device 21. Behind the roller drive 22, a further dancer 9c is arranged to control the web tension of the web material 1. The further dancer 9c can be controlled, for example, 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 further dancer 9c, a finishing device 23 is arranged, which is set up to assemble the web material 1 into individual sheets. For example, the web material 1 can be fed to the assembly device 23 and cut to a predetermined sheet size by means of a cutting device 24 of the assembly device 23 in order to assemble the web material 1 into individual sheets. The individual sheets are then directed to different transport paths 26a, 26b in a document switch 25. 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 was determined to be the correct print image are determined as document sheets 29 and are guided from the document switch 25 onto the transport path 26a leads into the document container 27. Sheets that carry a print image that was determined to be an incorrect print image are designated as waste sheets 30 and guided by the document switch 25 onto the transport path 26b, which leads into the reject container 28. In this way printed sheets that have errors in the printed image can be sorted out. 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 path of movement of the web material 1 behind the testing device 21 and in front of the assembly device 23. The bad marking device 31 is set up to provide a print image that has been determined to be an incorrect print image with a marking that identifies the print image as an incorrect print image. For example, the bad marking device 31 can comprise a print head for this purpose.

It can be provided that the print image comprises several 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 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 send printed sheets with a printed image that includes a number of individual printed images marked as incorrect individual printed images, which exceeds a predetermined maximum number of incorrect individual printed images, via the transport path 26b To supply reject container 28 and to supply other sheets to document container 27 via transport path 26a.

The Fig. 4 shows another printing device for printing on a printing substrate. In the design according to the Fig. 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 roll 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. This 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 Fig. 4 In the embodiment shown, a packaging module 44 includes the roller drive 22, the packaging device 23 with the cutting device 24, the document switch 25, the transport paths 26a, 26b, the document container 27 and the reject container 28.

List of reference symbols

1

Railway material

2

role

3

Printing table

4

feed direction

5

Print head 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

Support surface

14a, 14b

Printheads

15

Heating device

16

brush

17

Capping station

18

Pressure medium container

19a, 19b

Drying device

20

Test device

21

Image capture device

22

Roller drive

23

assembly facility

24

Cutting device

25

Document switch

26a, 26b

Transport routes

27

Document container

28

Reject container

29

Document sheet

30

Waste sheet

31

Bad marking device

40

Roll unwind module

41

Printing module

42

Drying module

43

Image processing module

44

Assembly module

Claims (14)

1. A device for printing a print substrate (1) having

   - a print head shuttle (5) with at least one print head (14a, 14b) that is configured to apply a printing medium to a print substrate (1) in order to generate a printed image, wherein the print substrate (1) is a web material that can be displaced along a web path in a feed direction (4) and the print head shuttle (5) is arranged on a first side of the print substrate (1); and

   - a printing table (3) with a support surface (13) that is arranged opposite the print head shuttle (5) on a second side of the print substrate (1), wherein the printing table (3) comprises a holding device (11) that is configured to hold the print substrate (1) in such a manner that a relative movement between the printing table (3) and the print substrate (1) is prevented for printing;

   wherein the print head shuttle (5) has a smoothing device (16) that is configured to come into contact with the support surface (13) of the printing table and to be moved over at least a portion of the support surface (13), in such a manner that it strokes over a print substrate (1) arranged on the support surface (13) of the printing table (3), in order to smooth it,

   characterized in that the smoothing device (16) extends along a longitudinal direction that runs parallel to the feed direction (4).
2. The device according to claim 1, characterized in that the smoothing device (16) is configured to be moved transversely, preferably perpendicularly, to the feed direction (4) over the support surface (13) of the printing table (3).
3. The device according to at least one of the preceding claims, characterized in that the smoothing device (16) is arranged on the print head shuttle (5) in such a manner that the smoothing device (16) moves together with the print head shuttle (5), wherein the smoothing device (16) is preferably arranged at the front of the print head shuttle (5) in relation to a movement direction of the print head shuttle (5).
4. The device according to at least one of the preceding claims, characterized in that the smoothing device (16) is movable transversely to a direction of movement of the print head shuttle (5) between a first and a second position.
5. The device according to claim 4, characterized in that the smoothing device (16) is in contact with the support surface (13) of the printing table (3) in the first position, so that the smoothing device (16) strokes over the print substrate (1) arranged on the support surface (13) of the printing table (3) during a movement, and that in the second position the smoothing device (16) is arranged over the printing table (3) in such a manner that the smoothing device (16) does not touch the print substrate (1) during a movement.
6. The device according to at least one of the preceding claims, characterized in that the smoothing device (16) has a length that is at least equal to a length of the support surface (13) of the printing table (3), wherein the length of the smoothing device (16) is preferably equal to, or greater than, a length of the print head shuttle (5).
7. The device according to at least one of the preceding claims, characterized in that the smoothing device comprises a brush (16).
8. The device according to at least one of the preceding claims, characterized in that the device is configured for a web material (1) that is a film material.
9. The device according to at least one of the preceding claims, characterized in that the holding device (11) comprises a vacuum device that is configured to draw the print substrate (1) against the printing table (3) by means of a vacuum, in order to hold the print substrate (1).
10. The device according to at least one of the preceding claims, characterized by:

    - a first web tension measuring device (7a, 8a) that is arranged along the web path upstream of the printing table (3) and is configured to generate first measurement data indicating a mechanical web tension of the print substrate (1) at the first web tension measuring device (7a, 8a);

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

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

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

    - a control device (10) that is configured:

    - to receive the first measurement data, to generate first control data based on the first measurement data and to control the first tensioning device (9a) according to 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); and

    - to receive the second measurement data, to generate second control data based on the second measurement data and to control the second tensioning device (9b) according to the second control data, in such a manner that the second tensioning device (9b) brings about a second predetermined web tension of the print substrate (1) at the second tensioning device (9b).
11. The device according to claim 10, characterized in that the control device (10) is configured, during a printing process, to keep the web tension of the print substrate (1) constant along the web path upstream of the printing table (3) and to keep the web tension of the print substrate (1) constant along the web path downstream of the printing table (3).
12. The device according to at least one of the preceding claims, characterized by a rejection device comprising:

    - an inspection device (20) with an image capture device (21) that is configured:

    - to capture an image of the printed image on the web material (1),

    - to compare the captured image of the printed image on the web material (1) with reference image data,

    - to identify the printed image as a correct printed image when a match is found between the printed image and the reference image data based on the comparison of the printed image on the web material (1) with the reference image data and

    - to identify the printed image as an incorrect printed image when no match is found between the printed image and the reference image data based on the comparison of the printed image on the web material (1) with the reference image data;

    - a finishing device (23) that is configured to process the web material (1) into individual sheets; and

    - a document diverter (25) that is configured to direct a finished sheet to one of a first transport path (26a) and a second transport path (26b), wherein

    - a finished sheet with a printed image that has been identified as a correct printed image is directed to the first transport path (26a) and

    - a finished sheet with a printed image that has been identified as an incorrect printed image is directed to the second transport path (26b).
13. A method for printing on a print substrate (1) comprising:

    - application of a printing medium to a print substrate (1), that is a web material (1) displaceable along a web path in a feed direction (4), by means of at least one print head (14a, 14b) of a print head shuttle (5) that is arranged on a first side of the print substrate (1), in order to generate a printed image;

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

    - smoothing of the print substrate (1) arranged on a support surface (13) of the printing table (3) by means of a smoothing device (16) that strokes over the print substrate (1) arranged on the support surface (13) of the printing table (3) by coming into contact with the support surface (13) of the printing table (3) and moving over at least a portion of the support surface (13), characterized in that the smoothing device (16) extends along a longitudinal direction that runs parallel to the feed direction (4).
14. The method according to claim 13,
    characterized in that the smoothing device (16) is movable transversely to a direction of movement of the print head shuttle (5) between a first and a second position, wherein the smoothing device (16) comes into contact with the support surface (13) of the printing table (3) in the first position, so that the smoothing device (16) strokes over the print substrate (1) arranged on the support surface (13) of the printing table (3) during a movement, and wherein in the second position the smoothing device (16) is arranged over the printing table (3) in such a manner that the smoothing device (16) does not touch the print substrate (1) during a movement.

Images