Apparatus for applying a stretching effect to a recording medium

Abstract

In a device and a method for exerting an extension on a recording medium (18) printed on its front side, the recording medium (18) is transported in a transport direction (P1). The recording medium (18) rests with its back side on at least one contact area (220a to 230a, 220b to 230b) of several support element areas of at least one support element arranged side by side transversely to the transport direction and projecting from a base body (140, 404, 500). At least a portion of the support element areas project from the base body (140, 404, 500) such that their end connected to the base body (140, 404, 500) is a greater distance from a side edge of the recording medium (18) than their contact area furthest from the base body (140, 404, 500).A vacuum is applied between at least two adjacent support element areas, by which the recording carrier (18) is moved in the direction of the base body (140, 404, 500) and at least part of the support element areas are deformed in such a way that they exert a force (F) on the recording carrier (18) directed in the direction of the respective side edge.

Description

[0001] In a device and method for applying stretching to a recording medium, the recording medium can be transported in a transport direction along a transport path. Some printing devices use page-width, fixed, non-movable printing units. Other printing devices use print heads that can move transversely to the transport direction, so that the image information is applied to the recording medium by scanning. This is independent of whether the recording medium is roll material or a single sheet. Furthermore, the recording medium can be moved beneath the application unit. Alternatively, or in combination, the recording medium is not moved, but rather the application unit. Here, an application unit can be a printing unit and / or a coating unit.

[0002] In inkjet printing, the liquid ink is applied unevenly to the recording medium, depending on the print image to be created. The recording medium can be sheets of paper, paper webs, or cardboard. However, other recording media, such as foils, can also be used.

[0003] When printing on paper with liquid ink, moisture gets into the paper, causing waves that, without further treatment, will remain on the paper even after the print image has been fixed. The moisture content is influenced, for example, by the water content, glycerol content, or similar liquids. Depending on the type of liquid, the recording medium swells at different rates. Furthermore, due to different print intensities in the different areas, the amount of liquid / ink is unevenly distributed. The waves in the paper are particularly pronounced in fully printed areas. Although paper waves also occur in other printing processes, such as offset printing, they are not as severe as in inkjet printing.

[0004] Likewise, the humidity in the fixing process is influenced differently locally. In printed areas with high ink concentrations, evaporation is often lower than in unprinted areas, partly due to film formation.

[0005] Due to the manufacturing process, paper has a machine direction (MD), i.e., the direction of transport of the paper during paper production, and a cross direction (CD), perpendicular to the machine direction and thus perpendicular to the direction of transport of the paper during paper production. Paper properties differ considerably between CD and MD in terms of stiffness, moisture expansion, and breaking strength. Paper swelling always depends on the main fiber direction. Fibers swell 20x less in the direction of the fiber than across it. For paper (a network of fibers) with partial orientation, the ratio is only 1:3 (MD:CD).

[0006] In high-performance printing with printing speeds of greater than 1 m / s up to currently 3 m / s, the web-like paper to be printed is often unwound from a paper roll. The machine direction is then in the unwinding direction, or the direction the paper is transported through the printing device. When printing single sheets, the machine direction is not uniformly defined and can vary from batch to batch.

[0007] In addition to inkjet, this printing process also includes all other digital and analogue printing methods such as electrophotography, offset printing, flexographic printing, and gravure printing. It also includes the application of varnishes with or without colorants.

[0008] Due to the liquid introduced into the paper via the ink (or the varying moisture distribution due to drying during the fusing process), the curl occurs primarily in the cross direction. In web-fed printing, the recording media is preferably unrolled along the MD direction and moved through the printer, so that the curl occurs when printing on paper webs transverse to the transport direction of the paper web.

[0009] The object of the invention is to provide a device and a method for exerting a force on a recording medium printed on its front side. This force is intended to actively stretch the recording medium to prevent rippling.

[0010] This object is achieved by a device having the features of claim 1 and by a method having the features of the independent method claim. Advantageous further developments are specified in the dependent claims.

[0011] The invention is based on the finding that the waves in the recording medium after printing with the aid of an inkjet printing device are also reduced after the print image has been fixed to the recording medium if a force in the cross direction is exerted on the recording medium during printing on the recording medium and / or between printing on the recording medium and / or during fixing of the print image on the recording medium. The cross direction refers to the direction in paper production and is always transverse to the web travel direction in web-fed printing. It has proven particularly advantageous if the force is exerted on the carrier material during fixing of the print image, in particular in the second half of the fixing unit in which the print image is fully fixed or fully dried.This force should have at least one force vector in the widest possible area in CD between the side edges of the recording medium.

[0012] However, when applying the force, the front side of the recording medium, on which the not yet fully fixed printed image is located, should not be contacted in order not to impair the printed image and / or hinder the fixing process or to avoid making an unprinted edge necessary.

[0013] The device having the features of claim 1 ensures that at least some of the support element regions are deformed in such a way that they exert a force on the recording medium directed in the direction of the respective side edge. The respective side edge is the side edge with the shortest distance to the contact region of the support element region. The contact regions contacting the rear side of the recording medium preferably exert a tensile force on the recording medium transversely to the transport direction of the recording medium, i.e., a force in the direction of the side edge. The recording medium is preferably a web-shaped recording medium, in particular a paper web.The material of at least the contact area of ​​the support element area is matched to the material of the recording medium in such a way that static friction exists between the contact area and the back of the recording medium, through which a force can be transmitted from the contact area to the recording medium, generating at least a tensile force along the recording medium that reduces or largely prevents the formation of waves due to the moisture introduced into the recording medium by the ink. This can significantly increase the quality of the printed recording medium.

[0014] Furthermore, it is advantageous if a first end of each support element region is connected to the base body, and if the contact region is arranged at the second end of the support element region remote from the base body. This allows the support element region to protrude from the base body, and the contact region to be arranged at a distance from the base body, so that the recording medium can rest on the contact regions.

[0015] It is also advantageous if the side edges of the moving recording medium run parallel to the transport direction. This allows for easy handling of the recording medium when applying the force to reduce and / or prevent waves in the recording medium.

[0016] Furthermore, it is advantageous if a first part of the support element regions is arranged to the left in the transport direction and a second part of the support element regions is arranged to the right in the transport direction of a center plane extending in the transport direction and orthogonal to the transport path and / or the recording medium. This allows the contact areas of the support element regions to exert a tensile force on the recording medium in two opposite directions, i.e., tensile force and counterforce. The recording medium is thus not displaced laterally during transport of the recording medium.

[0017] The transport unit can transport the recording medium in a transport plane, with a center plane of the transport path running orthogonally to the transport plane.

[0018] It is also advantageous if the end of at least some of the support element regions connected to the base body is spaced closer to a center plane extending in the transport direction and orthogonal to the transport path / recording medium than the contact region of the same support element. As a result, these support element regions extend away from the center plane or toward the side edges. Preferably, the support element regions arranged at the outer edges of the recording medium are inclined and / or curved and / or obliquely arranged, starting from the end connected to the base body, toward the respective side edge. Alternatively, or in combination, the support element could also be made from a solid material from which oblique slots have been milled, or from slightly preloaded bearings that allow "outward" rotation when negative pressure is present.When the vacuum is applied, the recording medium is then pulled toward the base body, exerting a force on the contact areas in the direction of the base body. Due to the oblique, tilted, and / or curved arrangement of the support element areas, these are moved outward toward the side edge and exert a force on the recording medium transverse to the transport direction, which exerts the force to reduce and / or prevent waves in the recording medium.

[0019] Furthermore, it is advantageous if the contact region of the first end of the support element region forms an angle apex, wherein the distance between the angle apex and the contact region forms a first angle leg and wherein the base body forms a second angle leg, wherein the angle of inclination thus defined is arranged in a plane orthogonal to the transport direction and preferably has a value in the range from 45° to 85°, preferably in the range from 65° to 75°.

[0020] It is particularly advantageous if the contact area is lip-shaped and / or if the support element area and / or the contact area extend parallel to the transport direction. This allows for a simple arrangement of the device relative to the recording medium, which can reduce or prevent waves in the recording medium.

[0021] It is also advantageous if the device is arranged below a fixing unit for fixing an inkjet print image and below the printed recording medium. As a result, the device is arranged on the back of the recording medium or opposite the back of the recording medium. It is particularly advantageous if the device is arranged below the second half of the fixing unit in the transport direction.

[0022] Also disclosed is an arrangement comprising a device having the features of claim 1 or according to a further development specified above and / or in the dependent claims and a recording medium, wherein the recording medium is in particular a paper web and / or individual sheets.

[0023] The method with the features of the independent method claim has the same advantages as the claimed device. In particular, the method can be further developed with the features of the dependent claims directed to the device and the aforementioned developments.

[0024] Embodiments of the invention are explained in more detail below with reference to the figures, in which: Figure 1 shows a schematic representation of an inkjet printer with at least one printing device, one fixing device and one device for exerting a force on a recording medium printed on its front side according to a first embodiment; Figure 2 shows a schematic representation of the device for exerting a force on a recording medium printed on its front side according to the first embodiment according to Figure 1; Figure 3 shows a schematic representation of a device for exerting a force on a recording medium printed on its front side according to a second embodiment; Figure 4a shows a contact area of ​​a support element area of ​​the device according to Figure 5 without recording medium; Figure 4b the contact area of ​​the support element area according to Figure 4a with the recording medium; Figure 5 shows a schematic representation of a device for exerting a force on a recording medium printed on its front side according to a third embodiment; Figure 6 shows a schematic representation of a device for exerting a force on a recording medium printed on its front side according to a fourth embodiment; and Figure 7 shows a schematic representation of a device for exerting a force on a recording medium printed on its front side according to a fifth embodiment.

[0025] Figure 1shows a schematic representation of an inkjet printer 10 with at least one inkjet printing unit 12, a fixing unit 14, and a device 16 for exerting a force on a recording medium 18 printed on its front side, according to a first embodiment. The inkjet printer 10 is, in particular, a high-performance printer with printing speeds of greater than 1 m / s up to currently 3 m / s.

[0026] The printing unit 12 serves to print the front side of the web-shaped recording medium 18, which is designed as a paper web. The recording medium 18 is fed to the printer 10, for example, by being unrolled from a roll using a dispenser 30. The transport direction of the recording medium 18 through the printer 10 is indicated by the arrow P1.

[0027] In the present embodiment, the printing unit 12 comprises four printing bars 20, 22, 24, 26 for each producing a color separation in the colors Y, M, C, K, and a unit for applying a primer to the recording medium 18 fed to the printing unit 12. The unit may comprise a further printing bar 28 for applying a primer. This printing bar 28 is then arranged upstream of the printing bars 20 to 26 for applying the ink.

[0028] A printing bar 20 to 28 of the printing unit 12 is preferably a unit that comprises at least one print head for printing a line onto the recording medium 18. When printing the color separations, neither the printing bars 20 to 28 nor the print heads of the printing bars 20 to 28 are moved. With the help of the printing bars 20 to 28, the recording medium 18 is printed page-wide. In particular, each printing bar 20 to 28 can comprise several print heads arranged one behind the other in two rows. The print head or print heads of the printing bars 20 to 28 can be controlled based on print image data to print color separations printed one above the other. The color separations printed one above the other then produce a print image.

[0029] The fixing unit 14 serves to create a robust surface by drying and fixing the ink-based print image generated by the printing unit 12 onto the recording medium 18. After printing with the fixed print images, the recording medium 18 is rewound into a roll using a rewinder 32. The roll containing the printed recording medium 18 can then be further processed at a later time.

[0030] In alternative embodiments, the printing unit 12 can have more or fewer printing bars 20 to 28 and / or can apply no primer. The printed recording medium 18 can also be fed directly to a further processing unit, such as a cutting unit for cutting the recording medium into individual sheets, without first being rewound. Instead of the rewinder 32, a further printer can also be arranged, with the aid of which the back of the recording medium is printed. The further printer can have an identical structure to the printer 10, with a known turning unit then being arranged between the two printers.

[0031] In inkjet printing, the ink, which is liquid in the printing state, is applied unevenly to the recording medium 18 depending on the print image to be created. This is necessary to achieve different colors, e.g., locally different colors in images. It is also conceivable for the print heads to also apply the ink, which is liquid in the printing state, from the side. The application of liquid ink causes moisture to penetrate the recording medium 18, causing waves in the recording medium 18. Without further measures, these waves remain on the recording medium 18 even after the print image has been fixed by the fixing unit 14. Furthermore, due to areas with different printing intensities, the amount of liquid / ink is unevenly distributed across the front of the recording medium 18. The waves in the recording medium 18 are particularly pronounced in areas of the recording medium 18 that are printed over the entire surface.

[0032] Due to the manufacturing process, the paper serving as the recording medium has a machine direction (MD), i.e., the transport direction of the paper during paper production, and a cross direction (CD), perpendicular to the machine direction and thus perpendicular to the transport direction of the paper during paper production. When printing on paper webs 18, the paper to be printed can be unwound from a paper roll. The machine direction is then in the unwinding direction or in the transport direction P1 of the paper web 18 through the printer 10.

[0033] Due to the liquid being introduced into the paper of the recording medium 18 via the ink, the corrugation occurs mainly in the cross direction, ie when printing paper webs 18 transversely to the transport direction of the paper web 18.

[0034] Waves in the transport direction P1 can be reduced, in particular, by exerting a tensile force in the transport direction P1 on the recording medium 18. For this purpose, the recording medium 18 can be pulled by transport elements, in particular by a corresponding drive of the unwinder 30 and the winder 32 and / or other transport elements of a transport unit for transporting the recording medium 18 through the printer 10.

[0035] In order to avoid or at least reduce waves transverse to the transport direction P1 in the recording medium 18, the printer 10 has a device 16 for exerting a force on the recording medium 18 printed on its front side with the aid of the printing unit 12. This device 14 exerts a tensile force on the recording medium 18 transverse to its transport direction P1, whereby the recording medium 18 is pulled apart by the tensile force when the printed image is fixed on the front of the recording medium 18. The position of the recording medium 18 transverse to the transport direction P1 remains unchanged.

[0036] The device 16 has a belt 38 guided around two deflection rollers 34, 36, of which preferably at least one deflection roller 34, 36 is driven, with segments each having multiple support element areas. One of these segments is designated by reference numeral 40. The back of the recording medium 18, either unprinted or with a pre-fixed printed image, rests on the support element areas. The belt 38 is driven in the direction of arrow P2 at the same speed as the recording medium 18 is moved in the transport direction P1.

[0037] The device 16 further comprises a unit 42 for applying a vacuum between at least two adjacent support element regions in order to move the recording medium 18 toward a base body of the segment 40 using the vacuum and to deform at least a portion of the support element regions. The unit 42 comprises a vacuum pump 44 and at least one vacuum distribution chamber 46, which is covered by a strip section. The support element regions protrude from the base body of the segment 40 toward the recording medium.

[0038] The structure and function of the device 16 will be described below in connection with Figure 2 explained in more detail.

[0039] Figure 2 shows a schematic sectional view of the device 16 according to Figure 1 . The cutting plane S runs in a plane orthogonal to the transport direction P1 through the Figure 1shown segment 40. The transport direction P1 is perpendicular to the sheet plane of the Figure 2The support element regions 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 protrude from the base body 140 of the segment 40 in the direction of the recording medium 18. The length of the support element regions 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112, from their end connected to the base body 140 to the end remote from the base body 140, decreases with increasing numbers of the reference symbols. The intention is to position the support elements (lips / breasts) increasingly more inclined outwards (i.e., with decreasing reference number), so that the stretching (stretching force per unit length) continuously increases laterally. The support element regions 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 have a contact area for contacting the recording medium 18 at their end remote from the base body 140.

[0040] In the base body 140 there are openings 120a, 120b, 122a, 122b, 124a, 124b, 126a, 126b 128a, 128b, 130a, 130b through which the negative pressure generated by the vacuum pump 44 reaches the areas between two adjacent support element areas 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 and there generates a negative pressure by means of which the recording medium 18 is pulled in the direction of the base body 140. As a result, the ends of the support element areas 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b that are remote from the base body are pressed downwards.Between the contact areas of the support element areas 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 and the recording medium, there is such a static friction due to their materials that the support element areas 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 exert a force on the recording medium further outwards towards the side edges of the web-shaped recording medium 18 when the recording medium 18 is pressed between the support element areas 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 towards the base body 140. This force F is represented by force vectors in . Figure 2 shown.

[0041] This force F causes the recording medium 18 to be pulled apart laterally on its front side during the fixing of the printed image, whereby the waves caused by the ink of the printed image in the recording medium 18 during the fixing process are reduced or at least completely eliminated when viewing the printed product thus produced. The device 16 is arranged below the fixing unit 14, with the recording medium 18 being guided between the fixing unit 14 and the device 16 for fixing. For this purpose, the printer 10 can comprise transport elements of a transport unit (not shown). The support element regions 100a, 100b, 102a, 102b, 104a, 104b, 106a, 106b, 108a, 108b, 110a, 110b, 112 extend, at least in one region, parallel to the side edge of the recording medium 18 or parallel to the center plane M.

[0042] Figure 3shows a schematic sectional view of a device alternative to device 16 for exerting a force on a recording medium 18 printed on its front side, according to a second embodiment. Elements with the same structure or the same function have the same reference numerals. The sectional plane S runs in a plane orthogonal to the transport direction P1 through the Figure 1 shown segment 40, where in Figure 3 the sectional view of an alternative segment 50 is shown.

[0043] The transport direction P1 of the recording medium 18 is perpendicular to the sheet plane of the Figure 3The segment 50 has support element regions 200a, 200b, 202a, 202b, 204a, 204b, 206a, 206b, 208a, 208b, 210a, 210b, which protrude from the base body 140 of the segment 50 in the direction of the recording medium 18. The length of the support element regions 200a, 200b, 202a, 202b, 204a, 204b, 206a, 206b, 208a, 208b, 210a, 210b decreases with increasing reference number from their end connected to the base body 140 to the end remote from the base body 140. Likewise, the inclination of the support element regions 200a, 200b, 202a, 202b, 204a, 204b, 206a, 206b, 208a, 208b, 210a, 210b decreases from their end connected to the base body 140 to the end remote from the base body 140 with increasing number of the reference symbols, so that the expansion increases outwards, i.e. with decreasing reference symbols.The support element regions 200a, 200b, 202a, 202b, 204a, 204b, 206a, 206b, 208a, 208b, 210a, 210b each have a specially shaped contact region 220a, 220b, 222a, 222b, 224a, 224b, 226a, 226b, 228a, 228b, 230a, 230b at their end remote from the base body 140 for contacting the recording medium 18. The structure and function of the contact regions 220a, 220b, 222a, 222b, 224a, 224b, 226a, 226b, 228a, 228b, 230a, 230b is used below in conjunction with the . Figures 4a and 4b explained in more detail.

[0044] Figure 4a and Figure 4b show, by way of example, for all contact areas 220a, 220b, 222a, 222b, 224a, 224b, 226a, 226b, 228a, 228b, 230a, 230b of the support element areas 200a, 200b, 202a, 202b, 204a, 204b, 206a, 206b, 208a, 208b, 210a, 210b the contact area 220a of the support element area 200a of the device according to Figure 3 . In Figure 4a the contact area 220a is without recording medium 18 and in Figure 4bwith recording medium 18, wherein the recording medium 18 in Figure 4bwas pulled by the negative pressure in the direction of the base body 140 and deforms the contact area 200a. The contact area 200a is designed as a double-walled system, which is configured such that when the recording medium 18 moves towards the base body 140, not only the non-double-walled area of ​​the support element area 200a is deformed towards the side edge, but also the double-walled area. Due to the opening 254 present between the two walls 250, 252 in the undeformed state and the oblique arrangement of the contact area 220a relative to the recording medium 18, a compression occurs in the area of ​​the wall 250 not in contact with the recording medium, as shown by the pair of arrows P3, and in the area of ​​the wall 252 contacting the recording medium 18, a movement towards the side edge of the recording medium 18 occurs, as shown by arrow P4.Arrow A indicates the direction of the movement of the recording medium 18 caused by the negative pressure. This movement indicates the force acting on the contact area 220a from the recording medium 18, which causes the deformation of the contact area 220a. In this embodiment, the force F acting on the recording medium 18 is caused both by a deformation of the entire support element area 200a toward the side edge and by a deformation of the double-walled contact area 220a.

[0045] Figure 5 shows a schematic sectional view of a device alternative to device 16 for exerting a force on a recording medium 18 printed on its front side according to a third embodiment. The sectional plane S runs in a plane orthogonal to the transport direction P1 through the Figure 1 shown segment 40, where in Figure 5the sectional view of an alternative segment 60 is shown. In this embodiment, only the support element regions 300a, 300b, 302a, 302b are elastically deformed by the negative pressure applied between these support element regions 300a, 300b, 302a, 302b and exert a force in the direction of the side edges only in the region of the side edges of the recording medium 18. Therefore, sealing lips are preferably used on the outside for the support element regions 300, 302. The other support element regions 304a to 322b serve only as support elements in the same way as the support element region 112 in the first embodiment. The other support element regions 304a to 322b can preferably be designed as brushes.

[0046] Figure 6shows a simplified schematic plan view of a device for exerting a force on a recording medium 18 printed on its front side, according to a fourth embodiment. Two circumferentially closed support element regions 400, 402 are arranged at a distance from one another, wherein the support element regions 400, 402 protrude from a base body 404 in the direction of the recording medium 18 (not shown). The support element regions 400, 402 are inclined and / or curved outwardly in the direction of the side edges and in and against the transport direction P1 in the same way as the support element regions 300a, 302a of the third embodiment. A plurality of openings are provided in the space between the spaced-apart support element regions 400, 402, one of which openings is designated by the reference numeral 406.This table-shaped arrangement is particularly suitable for fixation during start / stop operation of printer 10 or when printing single sheets. The direction of the force F exerted by the support element areas 400, 402 on the recording medium 18 is illustrated by the arrows.

[0047] Figure 7shows a simplified schematic plan view of a device for exerting a force on a recording medium 18 printed on its front side, according to a fifth embodiment. Four circumferentially closed support element regions 506 to 512 projecting on elliptical paths from a base body 500 in the direction of a recording medium 18 (not shown), as well as further support element regions 502, 504 arranged on elliptical paths and an outer support element region 514 arranged on a rectangular path, are arranged at a distance from one another. The support element regions 502, 504, 514 also project from the base body 500 in the direction of the recording medium 18 (not shown). The support element regions 502 to 514 are inclined and / or curved outwards in the same way towards the side edges and in and against the transport direction P1, as are the support element regions 300a, 302a of the third embodiment.A plurality of openings are provided in the space between the spaced-apart support element regions 502 to 514, one of which is designated by reference numeral 516. This table-shaped arrangement is particularly suitable for securing the printer 10 during start / stop operation or when printing single sheets. The direction of the force F exerted by the support element regions 502 to 514 on the recording medium 18 is illustrated by the arrows.

[0048] The devices according to the Figure 6 and 7 can also each form a segment 40 of the device 16. For this purpose, the base bodies 404, 500 can each be made of a flexible material, like the segments 40, 50, and 60. The contact areas of the receiving element areas of all embodiments can also be designed in the same way as the contact areas 220a to 230a and 220b to 230b.

[0049] All receiving element areas are made of an elastically deformable material, in particular of an elastically deformable plastic, such as an elastomer or rubber.

[0050] When printing single sheets, the machine direction is not uniformly defined and can vary from batch to batch. This must be taken into account, especially when applying the vacuum by device 16 in all embodiments.

[0051] The described support element areas are components of support elements or each form a support element.

[0052] It should be noted in general that a transport unit is not mandatory, as the recording medium can also be essentially immobile while the printing unit is moved across the recording medium. Particularly for single sheets, the present invention has the advantage that the inventive device can stretch the recording medium along the main plane of the recording medium after the application of liquid in the form of ink, finishing liquid such as varnish, etc., regardless of the orientation of the fibers, so that the corrugations are smoothed or even disappear completely. List of reference symbols

[0053] 10 Inkjet printer 12 Printing unit 14 Fusing unit 16 Device 18 Recording medium 20 to 28 Printing bar 30 Unwinder 32 Rewinder 34, 36 Deflection rollers 38 Ribbon 40, 50, 60 Segment 42 Vacuum unit 44 Vacuum pump 46 Vacuum distribution chamber 100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514, Support element areas / support elements 120a, 120b, 122a, 122b, 124a, 124b, 126a, 126b 128a, 128b, 130a, 130b, 406, 516 Openings 220a to 220b Contact areas 140, 404, 500 Base body P1, P2, P3, P4 Direction F Force S Cutting plane M Center plane

Claims

1. Device for exerting a stretching force on a recording medium, comprising a unit (16) which is arranged opposite the rear side of the recording medium (18), wherein the unit (16) has a plurality of support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) of at least one support element, which support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) each have at least one contact area (220a to 230a, 220b to 230b) on which the recording medium (18) rests with its rear side, wherein the support element areas (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) protrude from the base body (140, 404, 500) in the direction of the recording medium (18),wherein at least some of the support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) protrude from the base body (140, 404, 500) in such a way that their end connected to the base body (140, 404, 500) has a greater distance from a side edge of the recording medium than their contact region (220a to 230a, 220b to 230b) remote from the base body (140, 404, 500), and with a unit (42) for applying a negative pressure between at least two adjacently arranged support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) to move the recording medium (18) by means of the negative pressure in the direction of the base body (140, 404, 500) and to press at least a part of the support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402,502 to 514).

2. Device according to claim 1, characterized in that a first end of each support element region (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) is connected to the base body (140, 404, 500) and that the contact region (220a to 230a, 220b to 230b) is connected to the second end of the support element region (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514).

3. Device according to one of the preceding claims, characterized in that the side edges of the recording medium (18) run parallel to the transport direction (P1).

4. Device according to one of the preceding claims, characterized in thata first part of the support element regions (100a to 110a, 200a to 210a, 300a to 318a) are arranged to the left in the transport direction (P1) and a second part of the support element regions (100b to 110b, 200b to 210b, 300b to 318b) are arranged to the right in the transport direction (P1) of a central plane (M) extending in the transport direction (P1) and orthogonal to the transport direction (P1) and / or to the longitudinal axis of the recording medium (18).

5. Device according to one of the preceding claims, characterized in thatthe end of at least some of the support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) connected to the base body (140, 404, 500) has a smaller distance from a central plane extending in the transport direction (P1) and orthogonal to the transport direction (P1) and / or to the longitudinal axis of the recording medium (18) than the contact region (220a to 230a, 220b to 230b) of the same support element (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) .

6. Device according to one of the preceding claims, characterized in thatthe support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) arranged on the side edges of the recording medium (18) are inclined and / or curved and / or arranged obliquely towards the respective side edge, starting from the end connected to the base body (140, 404, 500).

7. Device according to one of the preceding claims, characterized in thatthe contact area (220a to 230a, 220b to 230b) of the first end of the support element area (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) forms an angle vertex, wherein the distance between the angle vertex and the contact area (220a to 230a, 220b to 230b) forms a first angle leg and wherein the base body (140, 404, 500) forms a second angle leg, wherein the thus defined angle of inclination is arranged in a plane (E) orthogonal to the transport direction (P1) and preferably has a value in the range of 45° to 85°, preferably in the range of 65° to 75°.

8. Device according to one of the preceding claims, characterized in that the contact region (220a to 230a, 220b to 230b) is lip-shaped and / or that the support element region and / or the contact region (220a to 230a, 220b to 230b) extends parallel to the transport direction (P1).

9. Device according to one of the preceding claims, characterized in that the device is arranged below a fixing unit (14) for fixing an inkjet print image on the recording medium (18), preferably in the transport direction (P1) below the second half of the fixing unit (14).

10. Method for exerting a stretching on a recording medium, in which the recording medium (18) rests with its rear side on at least one contact region (220a to 230a, 220b to 230b) of a plurality of support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) of at least one support element, said support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) protrude from the base body (140, 404, 500) in the direction of the recording medium (18), wherein at least some of the support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) protrude from the base body (140, 404, 500) in such a way that they are in contact with the base body (140, 404,500) has a greater distance to a side edge of the recording medium (18) than its contact region (220a to 230a, 220b to 230b) remote from the base body (140, 404, 500), and in which a negative pressure is applied between at least two adjacently arranged support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514), by means of which negative pressure the recording medium is moved in the direction of the base body (140, 404, 500) and at least a part of the support element regions (100a to 110a, 100b to 110b, 112, 200a to 210a, 200b to 210b, 300a to 318a, 300b to 318b, 400, 402, 502 to 514) are deformed in such a way that they exert a force (F) on the recording medium (18) directed in the direction of the respective side edge.

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