Abstract
A contact-less liquid application apparatus, and in particular a printing apparatus, for applying a liquid in a contact-less manner on a moving medium. The liquid application apparatus includes a liquid application means configured for applying a liquid on a moving medium, a media transport system configured for moving the medium in a movement direction at a distance of the liquid application means, and a flow control means configured to evacuate at least a portion of the air displaced by the moving of the medium, at least before the medium is in a liquid application position, where the liquid application position is a position in which the liquid application means is applying liquid on the medium.
Claims
1. A contact-less liquid application apparatus for applying a liquid in a contact-less manner on a moving medium, said liquid application apparatus comprising: a liquid application means configured for applying a liquid on a moving medium; a media transport system configured for moving the medium in a movement direction at a distance of the liquid application means; and a flow control means configured to evacuate at least a portion of the air displaced by the moving of the medium, at least before the medium is in a liquid application position, said liquid application position being a position in which the liquid application means is applying liquid on the medium.
2. The liquid application apparatus of claim 1, wherein the flow control means is configured to evacuate at least a portion of the air displaced by the moving of the medium in a zone upstream of the liquid application means and/or between the liquid application means and the media transport system.
3. The liquid application apparatus of claim 1, wherein the flow control means is configured to evacuate at least a portion of the air displaced by the moving of the medium in a zone before a front edge of the medium.
4. The liquid application apparatus of claim 1, wherein the flow control means is configured to evacuate at least a portion of the air displaced by the moving of the medium in a zone behind a trailing edge of the medium and/or in a zone next to one or more side edges of the medium and/or in a zone adjacent the medium.
5. The liquid application apparatus of claim 1, wherein the flow control means is configured to evacuate at least a portion of the air displaced by the moving of the medium, based on at least one of: the moving speed (v), a position of the medium (M) on the media transport system, and an operation state of the liquid application means.
6. The liquid application apparatus of claim 1, further comprising a measuring device configured for detecting a position of a front edge and/or a peripheral edge of the medium, wherein the flow control means is configured to evacuate at least a portion of the air displaced by the moving of the medium, based on the position detected by the measuring device.
7. The liquid application apparatus of claim 1, wherein the control flow means is configured to generate a suction flow shortly before the front edge reaches an area opposite the liquid application means, and such that the suction flow is reduced or stopped when the liquid application means have started applying liquid onto the medium.
8. The liquid application apparatus of claim 1, wherein the control flow means comprises at least one passage comprising: a passage located upstream of the liquid application means and having an inclination configured for guiding the suction flow away from a liquid application area; and/or a passage downstream of the liquid application means and having an inclination configured for guiding the suction flow away from a liquid application area.
9. The liquid application apparatus of claim 1, wherein the liquid application means comprises one or more printheads.
10. The liquid application apparatus of claim 1, wherein the flow control means comprises at least one suction means connected via at least one suction arrangement; and a controller configured for controlling the at least one suction arrangement and/or the at least one suction means such that at least a portion of the air displaced by the moving of the medium, is evacuated through the at least one hole.
11. The liquid application apparatus of claim 10, wherein the at least one suction arrangement comprises at least one valve means configured to regulate a suction flow in the at least one suction arrangement.
12. The liquid application apparatus of claim 11, wherein the media transport system comprises: a carrier having a support surface with at least one hole, said carrier being configured for supporting the medium on the support surface thereof; and a drive means configured for moving at least a portion of the carrier with the medium or for moving the medium relative to the carrier, in the movement direction with a moving speed; wherein the flow control means is integrated in the media transport system and the at least one suction means is connected via at least one suction arrangement to the at least one hole.
13. The liquid application apparatus of claim 12, wherein the controller is configured to control the at least one suction arrangements and/or the at least one suction means, such that the suction generated in an area where a medium is present is stronger than the suction generated in an area where no medium is present.
14. The liquid application apparatus of claim 12, wherein the carrier is provided with at least one passage ending in the at least one hole in the support surface, wherein the at least one passage comprises one or more of: a passage located upstream of the liquid application means and having an inclination configured for guiding the suction flow along the support surface of the carrier away from a liquid application area; a passage downstream of the liquid application means and having an inclination configured for guiding the suction flow along the support surface of the carrier away from a liquid application area; and a passage opposite the liquid application means.
15. The liquid application apparatus of claim 12, wherein the drive means is configured for moving at least the support surface of the carrier with the medium; wherein the carrier comprises a movable plate or belt with the at least one hole and a static support structure, and the drive means is configured to move the plate or belt; and wherein the at least one suction arrangement extends in the static support structure.
16-17. (canceled)
18. The liquid application apparatus of claim 12, wherein the drive means is configured for moving the medium relative to the carrier, and the carrier is static.
19. The liquid application apparatus of claim 12, wherein the at least one hole comprises more than 100 holes, wherein the distance between adjacent holes is between 1 mm and 400 mm.
20. The liquid application apparatus of claim 12, wherein the controller is configured to control the at least one suction arrangement and/or the at least one suction means to exert a suction force through the at least one hole between a front edge of the medium and an area opposite the liquid application means and/or in the area opposite the liquid application means, at least before the front edge reaches said area.
21. The liquid application apparatus of claim 1, wherein the flow control means is configured to deflect at least a portion of the air displaced by the moving of the medium, away from the media transport system, towards a zone upstream and/or downstream of the liquid application means; and wherein the flow control means is at least partially integrated in the liquid application means.
22. (canceled)
23. A liquid application method for applying a liquid in a contact-less manner on a moving medium, said method comprising the steps of: transporting a medium in a movement direction with a movement speed; evacuating at least a portion of the air displaced by the transporting of the medium, at least before the medium is in a liquid application position; and applying liquid on said medium in a contact-less manner when the medium has reached the liquid application position and while the medium is moving at the movement speed.
24-31. (canceled)
Description
BRIEF DESCRIPTION OF THE FIGURES
[0108] The accompanying drawings are used to illustrate presently preferred non-limiting exemplary embodiments of the present invention. The above and other advantages of the features and objects of the invention will become more apparent and the invention will be better understood from the following detailed description when read in conjunction with the accompanying drawings, in which:
[0109] FIG. 1A is a schematic exploded view of an exemplary embodiment of a media transport system, in particular for use in a printing apparatus;
[0110] FIG. 1B is a schematic cross section of the exemplary embodiment of FIG. 1A;
[0111] FIG. 1C is a schematic exploded view of another exemplary embodiment of a media transport system, in particular for use in a printing apparatus;
[0112] FIG. 1D is a schematic cross section of the exemplary embodiment of FIG. 1C;
[0113] FIG. 2 is a schematic top view of an exemplary embodiment illustrating an upper surface of a carrier on which a plurality of print media is arranged;
[0114] FIGS. 3A and 3B are schematic cross-sectional views of an exemplary embodiment of a carrier with a valve means, in a closed position and in an open position, respectively;
[0115] FIGS. 4A and 4B are schematic cross-sectional views of an exemplary embodiment of a carrier with valve means in an open position and in a closed position, respectively;
[0116] FIG. 5 is a cross-sectional view of an exemplary embodiment of a carrier with a conical passage;
[0117] FIG. 6 is a cross-sectional view of an exemplary embodiment of a printing apparatus comprising the media transport system;
[0118] FIGS. 7A and 7B are schematic cross-sectional views of an exemplary embodiment of a carrier with an integrated valve means in a closed and open position, respectively;
[0119] FIG. 7C is a top view of the valve means of FIGS. 7A and 7B;
[0120] FIGS. 8A-E illustrate another exemplary embodiment of a carrier with an integrated valve means with in FIG. 8A a schematic section A-A in the closed position of the valve means, in FIG. 8B a schematic section B-B, in FIG. 8C a schematic top view indicating A-A and B-B for a round variant, in FIG. 8D a schematic top view indicating A-A and B-B for a rectangular variant, and in FIG. 8E a schematic section A-A in the open position of the valve means;
[0121] FIG. 9 illustrates a schematic perspective view of another exemplary embodiment of a printing apparatus with a media transport system; and FIGS. 9A and 9B illustrate cross sections of possible implementations of details the media transport system of FIG. 9;
[0122] FIG. 10A illustrates a cross section of another exemplary embodiment of a printing apparatus with a media transport system, and FIG. 10B illustrates a schematic top view thereof; and
[0123] FIGS. 11-13 illustrate schematic cross sectional views of further exemplary embodiments of a liquid application apparatus.
DESCRIPTION OF EMBODIMENTS
[0124] The figures are not drawn to scale and purely diagrammatical in nature. Equal reference numerals in different figures refer to equal or corresponding features.
[0125] FIGS. 1A and 1B illustrate a media transport system, in particular for use in a printing apparatus. The media transport system comprises a carrier 100, 200 having a support surface, here an upper surface 101 with a plurality of holes 110. The carrier is configured to support a print medium M1, M2 on the upper surface 101 of the carrier 100, 200. A drive means (not shown) is configured for moving a portion, here a movable plate 100 of the carrier 100, 200 in a movement direction v, such that a print medium M1, M2 arranged thereon will also be moved in the movement direction v. The drive means may be configured to move the plate 100 and thus the medium M1, M2 at a speed of more than 0.5 m/s, preferably more than 1 m/s.
[0126] The plurality of holes 110 may be arranged according to a repetitive and/or regular pattern or may be positioned in an irregular and/or random manner. The holes 110 may be arranged, for example, in rows and columns as illustrated in FIG. 1A. However, the skilled person understands that many patterns are possible, and that the pattern may be adjusted depending on the type of media used and/or in function of the type of operation that has to be performed on the media whilst being transported by the media transport system.
[0127] In the exemplary embodiment of FIGS. 1A and 1B the carrier comprises a movable plate 100 with an upper surface 101 in which the plurality of holes 110 is arranged and a static support structure 200 for supporting the movable plate 100. The carrier 100, 200 comprises a plurality of suction groups 250 between the plurality of holes 110 and a suction means 300. In the illustrated embodiment each suction group 250 extends between six holes 110 and the suction means 300. Each suction group 250 comprises two rows of three passages 250a (associated with the six holes 110) through the movable plate 100, a suction chamber 250b in the support structure 200 and a suction line 250c in which a valve means 260 is included. For each operative position of the movable plate 100, the suction chamber 250b is, at an upper end thereof, in fluid communication with six passages 250a of the movable plate 100, and at a lower end thereof with the suction line 250c. The valve means 260 is operable to allow or interrupt the suction flow through the associated suction group 250, and in particular through the six holes 110 of the associated suction group 250. In the illustrated embodiment each suction group is associated with six holes 110, but the skilled person understands that each group 250 may be associated with less then six, e.g. one or two holes, or more than six holes.
[0128] Each valve means 260 may be controlled by a controller 400 such that automatically a suction force is exerted on a print medium M1, M2 present over the holes 110 associated with the suction group 250, and such that no suction force is exerted through the holes 110 associated with the suction group 250 when no print medium M1, M2 is present over said holes 110. When the valve means 260 is in an open position, the holes 110 of the associated suction group 250 are connected to the suction source 300, e.g. a vacuum source, such that the print medium M1, M2 is exposed to a suction force and is pulled to the upper surface 101 of the movable plate 100. The suction means 300 may comprise a vacuum pump or similar. It will be clear to the skilled person that the valve means 260 may also control the strength of the suction force exerted on the print medium M1, M2 by controlling the air flow through the valve means 260. For example, the valve means 260 may be controlled by using a variable duty cycle. The valve means 260 may be electrically controlled by the controller 400. Further developed embodiments may further adjust the suction flows caused by the valve means 260 based also on other parameters than the area covered by the medium. Also, in further developed embodiments, a suction flow through some of the non-covered holes 110 may be generated for other purposes, for example to evacuate any disturbing air flows, such as air flows caused by the movement of the medium, see further. It is noted that not all holes covered by a printing medium M1, M2 have to be in fluid communication with the suction means 300, and that in certain cases it may be sufficient to cause a suction force through only a subset of the covered holes, e.g. the holes near the edges of the medium M1, M2 and some holes in a centre of the medium M1, M2.
[0129] In order to be able to automatically control the valve means 260, the controller may receive input data representative for an initial position of a print medium M1, M2 on the movable plate 100 and of the moving speed v of the movable plate 100. Based on this input information, the valve means 260 can be controlled in function of time, such that at a specific moment in time only those suction groups 250 associated with the holes 110 below the print medium are activated. In other words, for the example of FIG. 1 where the print medium M1, M2 moves from left to right in function of time, the set of activated groups 250 will also move from left to right in function of time. In order to determine the position of the print medium on the movable plate 100, the media transport system may comprise a measuring device 600, such as a camera, a line scanner, a laser distance sensor, configured for detecting a position of the print medium on the movable plate 100. The controller 400 is configured to control the valve means 260 in function of the position detected by the measuring device 600. In other words the controller 400 may only open the valve means 260 where a print medium M1, M2 is arranged on the movable plate 100. Alternatively, a mechanical detection system (not shown) may be arranged in the carrier 100, 200 for detecting the position of the print medium M1, M2 on the carrier. The controller 400 may then be configured to control the valve means 260 in function of the position detected by the mechanical detection system. The controller 400 may further be configured to control the valve means 260 in function of a curvature detected by a sensor means (not shown) which is configured for detecting a curvature due to warping of the print medium M1, M2. By controlling the valve means 260 based on a detected curvature the fixation of the print medium M1, M2, and hence the printing quality may be improved.
[0130] Optionally, the controller 400 may further be configured to control the suction means 300. Also, optionally, the controller 400 may be configured to control the moving speed v of the movable plate 100, and thus of the print medium M1, M2 supported thereon. It is noted that the controller 400 may be implemented as a single control unit or as a plurality of separate control units.
[0131] In the embodiment of FIGS. 1A and 1B the plurality of suction groups 250 are associated with a single suction means 300, e.g. a single vacuum source, and the multiple valve means 260 control the multiple suction flows. For example, the valve means 260 may be controlled to be more or less open in function of the distance to an edge of the medium M, the distance from a front edge f1, f2 of the medium M, etc. Also, the timing may be controlled, e.g. in function of warp-related measures.
[0132] FIGS. 1C and 1D illustrate a variant of the embodiment of FIGS. 1A and 1B in which similar components have been indicated with the same reference numerals. Multiple suction means 300 (S1, S2, S3) are provided, e.g. in the form of multiple vacuum sources 300, which may be set or controlled independently of each other. The multiple suction sources 300 are associated with multiple hole zones Z1, Z2, Z3. The hole zones Z1, Z2, Z3 may correspond with lateral zones extending in a lateral direction perpendicular on the movement direction. In that manner, different suction strengths/pressures may be set in function of the location of the print medium M1, M2 with respect to the support structure 200. For example, the strength may be adjusted in an area where a printhead is present above the support structure 200. In other embodiments (not shown in FIGS. 1C and 1D), the hole zones may correspond with hole lanes extending in the movement direction, or with a combination of one or more hole lanes and one or more lateral hole zones. For example, a suction pressure of the suction source for a hole lane covered by a medium where the medium has a high warp height may be higher than a suction pressure of the suction source for another hole lane with a lower warp height. Also, the size and/or shape of the holes 110 and/or of the suction groups 250 of one hole zone may be different from the size and/or shape of the holes 110 and/or of the suction groups 250 of another hole zone.
[0133] FIG. 2 illustrates a top view of the carrier 100 wherein a plurality of holes 110 is arranged in an upper surface 101 thereof. A plurality of print media M1, M2 are shown to be arranged on the surface of the carrier 100 and move in a moving direction with a moving speed v. The print media M1, M2 are shown to cover a plurality of holes 110. The distance d1, d2 between adjacent holes may be between 4 mm and 400 mm. The lateral distance d1 measured in a direction perpendicular on the movement direction v and a longitudinal distance d2 measured in the movement direction v may differ depending on the pattern and the required accuracy on the lateral and longitudinal direction. Also, the distance d1, d2 does not have to be the same over the entire surface of the movable plate 100, and may vary in the between different rows or columns of holes 110. For example, the hole density may be higher at the edges than in the center of the plate 100 or vice versa. Also, holes 110 may be arranged according to a diagonal pattern. This may improve the distribution of the holes 110 and may improve the overall grip on the medium M1, M2 arranged on the carrier 100.
[0134] FIGS. 3A and 3B illustrate a cross-sectional view of another exemplary embodiment of a carrier 100, 200 with a valve means 270. The valve means 270 is shown in a closed position in FIG. 3A and in an open position in FIG. 3B. The valve means 270 is shown to be arranged in the carrier between a static upper plate 100 and a static lower support structure 200. The upper plate 100 is provided with a plurality of holes 110. Each hole is associated with a valve means 270. The valve means 270 comprises a closure body 270, in the example of FIGS. 3A and 3B shaped as a sphere with a protruding portion configured to protrude through the associated hole 110 when no print medium is present. The closure body 275 is carried by a spring means 276 configured for exerting a spring force on the closure body 275 in the direction of the hole 110. Each closure body 275 is configured and arranged for blocking a fluid passage through the associated hole 110 when no print medium is present above said hole 110. The closure body 275 is further configured to allow a fluid passage through the hole 110 when a print medium M is present above said hole 110. When no print medium M is present above the hole 110, the valve means 270 is in the closed position, see FIG. 3A. When the print medium M is moved relative to the carrier 100, 200 in a movement direction with a moving speed v, to a position where the print medium M is present above the hole 110, the print medium pushes the closure body 275 downwards such that the valve means 270 is moved to the open position 110, see FIG. 3B. In this position the hole 110 is in fluid communication with a suction means 300 via a suction group 250 consisting of a passage 250a through the plate 100 and a suction chamber 250b underneath the plate 100, between the plate 100 and a suction means 300. The print media M is thereby exposed to a suction force. Thus, the valve means 270 is configured such that automatically a suction force is exerted on the print medium, when the print medium M is present above the hole associated with the valve means 270. When the print medium is moved away from the hole 110, the spring means 276 will position the closure body 275 back in the closed position, see FIG. 3A. The closure body 275 may be of any suitable form, as is further illustrated in the following exemplary embodiments.
[0135] FIGS. 4A and 4B illustrate cross-sectional views of another exemplary embodiment of a carrier 100, 200 comprising a valve means 280. In FIGS. 4A and 4B, the carrier comprises a movable plate 100 with a plurality of holes 110 and a static support structure 200. Each hole 110 id provided with a valve means 280 which is integrated in the movable plate 100 and configured for blocking a fluid passage through the hole 110 when no print medium is present above said hole 110a, and for allowing a fluid passage through said hole 110 when the print medium is present above said hole. While FIGS. 4A and 4B illustrate a mechanical valve means 280 integrated in the movable plate 100, the static support structure 200 or the movable plate 100 may alternatively comprise electrically controlled valve means. In this case a controller (not shown) may be configured for controlling each valve means in function of the moving speed and in function of the position of the print medium M on the carrier 100, 200, similar to the embodiment of FIGS. 1A and 1B. In yet another embodiment, instead of using a mechanical valve means 280 which is activated by the weight of the print medium, the valve means 280 may be electrically controlled by a sensor, e.g. a distance sensor, sensing the presence of a print medium above the hole
[0136] The valve means 280 of FIGS. 4A and 4B has a piston-like closure body 285, and is arranged in a passage 250a connecting the hole 110 in the upper surface 101 with a suction chamber 250b in the static support structure 200. Passage 250a and suction chamber 250b form a suction group 250 between the hole 110 and the suction means 300. The closure body 285 of the valve means 280 comprises an upper section 281 protruding out of the upper surface 101 of the movable plate 100, when no print medium M is present above the associated hole 110, and a lower section 282 having a flange portion intended to abut against an abutment surface 255 in the passage 250a through the plate 100. The lower section 282 can be arranged in sealing engagement with the abutment surface 255 by a spring means 286, such that substantially no leakage is allowed through the hole 110, when no print medium M is present above the hole. When the print medium is arranged above the hole 110, as is illustrated in FIG. 4B, the piston-like closure body 285 is pushed down such that the seal is broken and airflow is permitted through the hole 110 such that a suction force is exerted on the print medium M. In similar fashion as illustrated in FIG. 3, the spring means 286 pushes the piston-like closure body 285 back into the closed position when the print medium is no longer present above the hole. The term sealing refers to the sealing of the hole 110 such that no air flow is permitted. In other words, the hole is closed. To that end, a sealing material may be arranged in the sealing area, for example a seal fabricated from rubber. This further reduces the leakage rate, thereby reducing the energy consumption of the media transport system.
[0137] FIG. 5 illustrates yet another embodiment of a static carrier 100, 200 supporting a print medium M which is moved with a movement speed v along the carrier 100, 200. The carrier comprises a plate 100 with an upper surface 101 in which a plurality of holes 110 are arranged. The plate 100 is provided with a plurality of passages 250 between the plurality of holes 110 in the upper surface 101 and a rear surface 102. The passage 250 has a wall oriented at an angle a smaller than 90 degrees with respect to the upper surface 101. More in particular, the hole 110 may be ring shaped and the corresponding passage 250 may comprise a conically ring-shaped wall portion 251. Optionally the conically ring-shaped wall portion 251 may merge into a cylindrical portion 252. Optionally a central body 255, here a conical body, may be arranged in the passage 250. The lower end of the passage 250 is connected to a valve means 260 which may be controlled by a controller 400 in a similar manner as described above in connection with FIGS. 1A and 1B. Such an embodiment has the advantage that the suction flow is not oriented perpendicular on the upper surface 101. Especially in areas where nozzles, such as inkjet nozzles are arranged above the print medium, it is advantageous to avoid air flows in the zone where ink is being deposited on the print medium. FIGS. 5A and 5B illustrate two other possible variants of the embodiment of FIG. 5 where the passage 250 has a wall oriented at an angle a smaller than 90 degrees with respect to the upper surface 101. In the embodiment of FIGS. 5A and 5B the passage 250 has a wall extending at an angle a with respect to the upper surface 101 which is below 60°. In the embodiment of FIG. 5A the passage 250 may be e.g. cylindrical or prism shaped with an axis making an angle a with the upper surface. In the embodiment of FIG. 5B the passage 250 has a curved wall allowing to further reduce the angle a.
[0138] FIG. 6 is a schematic representation of an exemplary embodiment of a printing apparatus comprising a media transport system 1000 according to any one of the embodiments disclosed above, and a plurality of printheads, such as inkjet printheads 501, 502, 503, 504 arranged above the carrier 100, 200 of the media transport system 1000. The printing apparatus further comprises an infeed means 600, e.g. a roller, configured to press the print medium M against the upper surface of the carrier 100, 200. Optionally a control means may be provided configured for controlling the valve means (not shown in FIG. 6, but may be implemented as described above) of the media transport system 1000 in function of the distance between a hole associated with said valve means and the one or more printheads 501, 502, 503, 504 and/or in function of an operation state of the one or more printheads 501, 502, 503, 504 and/or in function of a speed v of the print medium (M). Such control means may be part of the controller 400 illustrated in FIGS. 1A and 1B, or may be a separate control means. For example, the suction force may be lower for the holes immediately below the printheads 501, 502, 503, 504, in order to avoid that the path of the liquid (e.g. ink) which is applied (e.g. jetted) by printheads 501, 502, 503, 504 is influenced by the suction flow. Also, optionally there may be provided a control means configured for controlling the valve means such that the suction force exerted in a central zone of a print medium is different from the suction force exerted in an edge zone of the print medium.
[0139] FIGS. 7A-C illustrate an alternative embodiment of a carrier 100, 200 with a valve means which is integrated in the carrier 100, 200. The embodiment is similar to the embodiment of FIG. 5, with this difference that the valve means are made in one piece with the movable plate 100 of the carrier. To that end, the movable plate 100 may be fabricated entirely from a resilient material or may comprise valve means arranged in the movable plate which are fabricated from resilient material. In similar fashion as previously described, the suction groups 250 may comprise passages 250a through the plate 100 and suction chambers 250b in the static support structure 200, which are connected to the suction means 300. The valve means 280 are integrally formed with the movable plate 100 with an upper portion 281 of the valve means 280 extending beyond the upper surface of the movable plate 100 in the closed rest position of the vale means 280. The valve means 280 has a lower portion 282 with a bendable part 284 connected to a wall part of the passage 250a, and with a flange 283 intended to be in contact with an abutment surface 255 protruding out of the wall of the passage 250a in the closed position of the valve means 280, see FIG. 7A. When the print medium M is present above the hole 110, as shown in FIG. 7B, the closure body 285 of the valve means 280 is bent inwardly such that the seal formed by the flange 283 and the abutment surface 255 is broken and a suction force is exerted on the print medium M. When the print medium is no longer present above the hole 110, the bendable part 284 which is made from the resilient material will bend back into the sealed position. FIG. 7C illustrates a top view of an integrated valve means 280 wherein the flange 283 is shown to extend beyond the abutment surface 255 arranged in the passage 250a, thereby forming a seal.
[0140] FIGS. 8A-8D illustrate yet another exemplary embodiment of a carrier with a plate 100 with an integrated valve means 280, which is similar to the embodiment of FIGS. 7A-7C with this difference that the lower portion 282 is provided with two sealing flanges 283 and two bendable connecting parts 284 on opposite sides of the closure body 285. As illustrated in FIGS. 8C and 8D, the closure body 285 may be embodied as a round variant (FIG. 8C) arranged in a cylindrical passage 250a or as a rectangular variant (FIG. 8D) arranged in a prism shaped passage 250a. FIG. 8E illustrates the integrated valve means 280 in an open position where the two seal flanges 283 are moved away from the two abutment surfaces 255 protruding out of a wall of the passage 250a.
[0141] FIG. 9 illustrates a further developed embodiment of a printing apparatus with a media transport system having multiple holes zones. Similar components have been indicated with the same reference numerals as in the previous embodiments. The plurality of holes 110 are arranged in different hole zones Z1, Z2a, Z2b, Z3a, Z3b, Z4. As illustrated in FIGS. 9A and 9B, the holes 110 and the corresponding suction groups 250 of a different hole zone may have a different shape and/or size and/or may be associated with a different suction means S1, S2, S3, S4 in order to obtain different suction flows. The size and/or shape of the holes 110 and/or suction groups 250 of one hole zone may be different from the size and/or shape of the holes 110 and/or suction groups 250 of another hole zone. The hole zone Z4 corresponds with a central hole lane extending in the movement direction v, and the hole zone Z1 corresponds with a lateral hole zone extending perpendicular on the movement direction v. Further holes zones Z2a, Z2b, Z3a, Z3b extend on either side of the central hole lane Z4. Hole zone Z1 which is arranged upstream and/or underneath the printhead may be used for evacuating an air flow caused by the movement of the print medium M as will be further explained in connection with FIG. 10. Holes zones Z2a, Z2b, Z3a, Z3b, Z4 may be controlled independently e.g. in function of a type of warping, a location of the medium on the carrier 100, 200, etc. For example, when a medium covers both zones Z3a, Z3b and Z4, the suction force exerted in Z4 may be lower than in zone Z3a, Z3b in order to avoid that the friction between the medium and the carrier is too higher and/or in order to compensate for warping at the edges of the medium.
[0142] FIGS. 10A and 10B illustrate yet another exemplary embodiment of a liquid application apparatus, here a printing apparatus with a media transport system and a flow control means 2000 configured to evacuate at least a portion of the air displaced by the moving of the medium. The media transport systems comprises a carrier 100, 200 having an upper surface 101 with a plurality of holes 110 (in FIGS. 10A and 10B only the holes near the printhead 500 are shown but it will be understood that more holes may be present, and the holes may be implemented in any suitable way described above). The carrier 100, 200 is configured for supporting a print medium M on the upper surface 101 thereof. In the embodiment of FIG. 10A, a drive means (not illustrated) may be configured either to move a belt or table 100 with holes 110 relative to a static support structure 200 as in the embodiment of FIGS. 1A-1D, or to move the print medium M relative to the carrier 100, 200, as in the embodiment of FIG. 5. The print medium M is moved in a movement direction with a moving speed v.
[0143] The flow control means 2000 comprises at least one suction means 300 connected via a plurality of suction arrangements 250. The plurality of suction groups or arrangements 250 is present between the plurality of holes 110 and the at least one suction means 300 (here as an example two suction means S1 and S2 are shown). The plurality of suction groups 250 comprises a corresponding plurality of valve means 260 operable to allow or interrupt a suction flow through one or more holes 110. The plurality of valve means 260 is controlled by a control means 400b configured for controlling the plurality of valve means 260 such that at least portion of the air displaced by the moving of the medium M, is evacuated through at least one hole of the plurality of holes 110 in a zone Z1 before of a front edge f of the medium M, and upstream of the printhead. Also, at least one further hole 110 may be provided in a zone Z2 downstream of the printhead 500. In that manner, any air flows disturbing the printing can be at least partially avoided. In other words, holes 110 may not only be used to pull the medium M onto the carrier 100, 200, but also to evacuate an air flow around the medium M, such that disturbing air flows underneath the printhead are avoided.
[0144] In the illustrated example, the medium may be cardboard and have a thickness B between e.g. 0.5 mm and 10 mm. The thickness A of the air flow above the medium may be e.g. 5 mm to 20 mm. The distance C between the carrier and the printhead may be 0.5 mm to 2 mm more than the thickness B of the cardboard.
[0145] One or more printheads 500 are arranged above the carrier 100, 200. The control means 400a may be further configured to control the plurality of valve means 260 to exert a suction force in the zones Z1, Z2 upstream of the front edge f of the medium M, at least shortly before the front edge f arrives underneath the printhead 500. The air flow caused by the movement of the cardboard M may follow first a convex path caused by the movement and next a concave path caused by the suction through the holes 110 in zone Z1 between the front edge f and the area below the printhead 500.
[0146] The media transport system may further comprise a measuring device 700, such as a camera, a scanner, one or more sensors, configured for detecting a position of at least a front edge f of the medium M, wherein the control means 400b is configured to control the valve means 260 in function of the position of the front edge f detected by the measuring device 700.
[0147] In the illustrated embodiment, the carrier 100, 200 is provided with a plurality of passages 250b ending in the plurality of holes 110 in the upper surface 101. The passage 250b in zone Z1 has a wall oriented at an angle a smaller than 90 degrees with respect to the upper surface 101. For example, angles between 30 and 70 degrees may be used to create a suction flow which is not vertical with respect to the upper surface, and which follows more or less the flow lines of the air flow to be evacuated. More in particular, the inclination may be oriented in an upstream direction, i.e. in the direction of an approaching front edge f. In zone Z2, downstream of the printhead 500, the passages 250b may be inclined in the opposite direction, such that air flows underneath the printhead are limited or avoided. Indeed, by giving the passages 250b in zone Z2 an inclination in the movement direction, the suction flow is oriented away from the printhead 500. For example, the passages 250b upstream of the printhead 500 (in zone Z1) may have a mirror shape of the passages 250b downstream of the printhead 500 (in zone Z2). In other zones of the carrier 100, 200, any one of the implementations described before for the suction groups 250 may be used.
[0148] In the description provided above, it is described that the valve means 260 are controlled. However, when a plurality of suction means 300 (S1, S2) is present, as in the embodiment of FIGS. 1C and 1D, in addition or alternatively, it is also possible to control the plurality of suction means 300 using a control means 400a. It is noted that the control means 400b and 400a may be part of the same control unit or may be separate control units.
[0149] More generally, the printing apparatus may comprise a control means 400a, 400b configured for controlling the plurality of valve means 260 and/or the at least one suction means 300 in function of the distance between said valve means 260 and the one or more printheads 500 and/or in function of an operation state of the one or more printheads 500 and/or in function of a speed of the print medium M and/or in function of a position of the print medium M on the carrier and/or in function of a position of the front edge f of the print medium M, etc.
[0150] In the embodiment of FIGS. 10A and 10B, the flow control means 2000 is integrated in the media transport system. The controllers 400a, 400b may be configured to control the at least one suction arrangements 250 and/or the at least one suction means 300, such that the suction generated in an area where a medium is present is stronger than the suction generated in an area where no medium is present.
[0151] FIG. 11 illustrates another exemplary embodiment of a contact-less liquid application apparatus, and in particular a printing apparatus, for applying a liquid in a contact-less manner on a moving medium M. The liquid application apparatus comprises a liquid application means 500 configured for applying a liquid on the moving medium M, and a media transport system 1000 configured for moving the medium M in a movement direction v at a distance of the liquid application means 500. The liquid application means may be one or more print heads, e.g. one or more inkjet printheads. The liquid application apparatus further comprises a flow control means 2000 configured to evacuate at least a portion of the air displaced by the moving of the medium M, at least before the medium is in a liquid application position, but in the embodiment of FIG. 11, the flow control means 2000 may continue to operate during application of the liquid by the liquid application means 500. A liquid application position is a position in which the liquid application means 500 is applying liquid on the medium. FIG. 11 illustrates the medium M before it is in the liquid application position.
[0152] The flow control means 2000 is configured to evacuate at least a portion of the air displaced by the moving of the medium in a zone upstream of the liquid application means 500. The evacuation may take place in a zone before a front edge f of the medium M, but also above the medium M when the medium M is in a liquid application position. Although not illustrated, the skilled person understands that similar flow control means may be provided to evacuate at least a portion of the air displaced by the moving of the medium in a zone behind a trailing edge of the medium M and/or in a zone next to one or more side edges of the medium.
[0153] The flow control means 2000 may be configured to evacuate at least a portion of the air displaced by the moving of the medium M, taking into account at least one of: the moving speed v, a position of the medium M in the media transport system 1000, an operation state of the liquid application means 500. Optionally, a measuring device 700 configured for detecting a position of the front edge f and/or a peripheral edge of the medium, may be provided. The flow control means 2000 may then be configured to evacuate at least a portion of the air displaced by the moving of the medium M, taking into account the position detected by the measuring device. The control flow means 2000 may be configured to generate a suction flow shortly before the front edge f reaches an area opposite the liquid application means, and such that the suction flow is reduced when the liquid application means 500 have started applying liquid onto the medium. More in particular, the suction flow behaviour may be optimized to avoid or limit any disturbance of the application of liquid by the liquid application means 500.
[0154] To shape the air flow appropriately, the control flow means 2000 comprises at least one passage 2250b located upstream of the liquid application means 500 and having an inclination configured for guiding the suction flow away from a liquid application area A and from the path followed by the liquid leaving the liquid application means 500. The shape of an inlet 2210 of the passage 2250b may be substantially any one of the following or a combination thereof: round, rectangular, ring-shaped, oval, polygonal.
[0155] The flow control means 2000 comprises at least one suction means 2300 connected via at least one suction arrangement 2250 comprising the above described passage 2250b. Optionally a valve means (not illustrated) may be included in the suction arrangement 2250. The flow control means 2000 further comprises a controller 2400 configured for controlling the at least one suction arrangement 2250 and/or the at least one suction means 2300 such that at least a portion of the air displaced by the moving of the medium, is evacuated through the above described passage 2250b. The flow control means 2000 is configured to deflect at least a portion of the air displaced by the moving of the medium M, away from the media transport system 1000, towards a zone upstream of the liquid application means 500. The flow control means 2000 may be at least partially integrated in the liquid application means 500.
[0156] In the embodiment of FIG. 11, a liquid is applied in a contact-less manner on the moving medium M by: transporting the medium M in a movement direction with a movement speed v; evacuating at least a portion of the air displaced by the transporting of the medium M, at least before the medium M is in a liquid application position; and applying liquid on said medium M in a contact-less manner, when the medium M has reached the liquid application position and whilst the medium is moving at the movement speed v. The transporting may be done on a carrier with a support surface, for example a carrier as described in the previous embodiments, but this may also be a different carrier. Optionally the evacuation described in FIGS. 10A and 10B may be combined with the evacuation described in FIG. 11.
[0157] The embodiment of FIG. 12 is similar to the embodiment of FIG. 11, with this difference that the flow control means 2000 comprises a first suction arrangement 2250 upstream of the liquid application means 500, and a second suction arrangement 2250′ downstream of the liquid application means 500. Further, the suction arrangements 2250, 2250′ each comprise a valve means 2260, 2260′ controlled by a controller 2400, and there is provided a common suction means 2300 for the suction arrangements 2250, 2250′.
[0158] To shape the air flow appropriately, the first suction arrangement 2250 comprises at least one passage 2250b located upstream of the liquid application means 500 and having an inclination configured for guiding the suction flow away from a liquid application area A and from the path followed by the liquid leaving the liquid application means 500. Similarly, the second suction arrangement 2250′ comprises at least one passage 2250b′ located upstream of the liquid application means 500 and having an inclination configured for guiding the suction flow away from a liquid application area A and from the path followed by the liquid leaving the liquid application means 500. The shape of an inlets 2210, 2210′ of the passages 2250b, 2250b′ may be substantially any one of the following or a combination thereof: round, rectangular, ring-shaped, oval, polygonal. More in particular, the passages 2250b, 2250b′ may be shaped in a similar manner as the passage 250b described above in connection with FIGS. 10A and 10B but mirrored around a horizontal plane.
[0159] FIG. 13 illustrates yet another exemplary embodiment of a liquid application means for which similar components have been indicated with the same reference numerals. In this embodiment, the flow control means 2000 comprises at least one suction means 2300 connected via at least one suction arrangement 2250 comprising a passage 2250b through the media transport system 1000 at a location upstream of a liquid application area A. To that end, as illustrated, the media transport system 100 may comprises two carriers 100a, 100b, e.g. two belts, placed at a small distance of each other. Optionally a valve means (not illustrated) may be included in the suction arrangement 2250. The flow control means 2000 further comprises a controller 2400 configured for controlling the at least one suction arrangement 2250 and/or the at least one suction means 2300 such that at least a portion of the air displaced by the moving of the medium, is evacuated through the above described passage 2250b. The flow control means 2000 is configured to deflect at least a portion of the air displaced by the moving of the medium M, through the media transport system 1000.
[0160] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination, and any advantageous combinations of such claims are herewith disclosed. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
