Ink printer and method for making prints on web-like recording medium

Abstract

To prevent a print bar from being smeared readily due to the high throughput rate of an ink and high transport speed.SOLUTION: In order to make prints on a recording medium (11), the recording medium is moved to a print position (30) in a horizontal direction by a web carriage (20). Then, the recording medium is moved up to a print head. In order to clean the print head, a maintenance unit (21) is used. The maintenance unit is moved to a maintenance position below a print bar (14) in the horizontal direction. Next, in order to attach a cover cap (27) to the print head or clean the print head, a cleaning unit (40) including the cover cap (27) is moved up toward the print head. Advantageously, the web carriage (20) and the maintenance unit (21) can be moved only in the horizontal direction and a print unit (12) remains with its position fixed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , ,

[0001] The present invention relates to a high-print-output ink printer for printing on a web (winding paper) - shaped recording medium. Further, the present invention relates to a method for printing on a web-shaped recording medium with ink.

[0002] An ink printer can be used to perform single-color or multi-color printing on a web-shaped recording medium made of various materials, such as paper. The structure of such an ink printer device is well-known. In particular, a digital high-speed ink printer that ejects ink droplets from the nozzles of a print head to generate a printed image on a web-shaped recording medium moving at high speed is known.

[0003] Especially in multi-color inkjet printers, usually, a plurality of print bars are provided for various inks, and each print bar is provided with one or more print heads respectively. Due to the high throughput and high conveyance speed of the ink, the print bar (i.e., the nozzle plate of the print head) may get dirty soon. Therefore, in order not to impair the print quality, the print head must be cleaned repeatedly.

[0004] Printhead cleaning is performed in a predetermined cycle by so-called flushing (purging) and wiping to clean ink residue or other contaminants from the printhead. Flushing involves forcefully expelling ink from all print nozzles of the printhead for a short period of time, thereby cleaning the nozzles with a flow-through. In wiping, liquid residue is wiped away from the nozzle plates by a wiper blade. Instead of a wiper, a fleece-like absorbent cleaning tape can be used to mechanically and / or wet-clean the nozzle plates. Additionally or alternatively, wet cleaning can also be performed as in the conventional method. In this case, a cleaning solution is sprayed onto the nozzle plates before wiping to separate deposits and contaminants on the nozzle plates. The nozzle plates are then wiped.

[0005] German Patent Application Publication No. 102010037829 describes an ink printer in which the printing unit can be moved from a printing mode position above the transport path of the recording medium to a maintenance position located laterally to the transport path of the recording medium. In this maintenance position, the print head can be accessed from below, and the nozzle plates of the print head can be cleaned. The printing unit of a high-power printer is connected to numerous electrical and optical lines for power supply or for transmitting control signals to the print head, as well as multiple mechanical conduits and hoses for supplying ink. Because it is necessary to move a partially very large printing unit, such supply units are formed to be extremely flexible, and large, long drag chains are required to guide these lines. Thus, in such known device concepts, the technical effort is relatively large, and the space required is also increased by the lateral movement of the printing unit.

[0006] To avoid such problems, an ink printer for printing with ink on a web-like recording medium is known, as described in German Patent No. 102013106211, in which the position of the printing unit remains substantially fixed. For cleaning the print head, the recording medium, which is located in a longitudinally movable transfer loop and extends over various rollers, is moved horizontally from the printing position to the resting position. This frees up space, into which a cleaning unit, previously positioned below the transfer loop, is then moved vertically upward.

[0007] In this type of ink printer configuration, two relatively large modules (a cleaning unit and a transfer loop) are moved in directions perpendicular to each other and travel relatively long distances. Therefore, such a configuration requires a large space, especially one with considerable height, to allow sufficient room for movement without collisions.

[0008] The object of the present invention is to provide an ink printer and method for printing on a web-like recording medium that requires only reduced configuration space while maintaining improved technical reliability.

[0009] This problem is solved with respect to the ink printer by the features of claim 1, and with respect to the method by the features of claim 10.

[0010] In other words, the ink printer has a printing unit that is fixedly positioned within the ink printer. A movable web guide unit is positioned to move linearly along guide elements in a plane below the printing unit. A movable service unit for maintaining the printing unit is similarly positioned below the printing unit to move linearly along guide elements. Thus, the web guide unit and the service unit move axially in the same plane along the same linear guides.

[0011] The web guide unit is positioned in the print bar area below the print unit in print mode to guide and print the recording medium. The maintenance unit is positioned below the print unit in maintenance mode to maintain the print bar. The web guide unit and the maintenance unit are mechanically connected to each other in a removable manner, allowing them to move linearly horizontally along the guide element, independently or together. The web guide unit is positioned directly below the print unit in print mode, and the maintenance unit is positioned directly below the print unit in maintenance mode. Depending on the desired mode state, the corresponding unit is moved to a position where it fits linearly horizontally.

[0012] In operating an ink printer for printing on a web-like recording medium with ink, the first step is to move the web guide unit linearly to the printing position below the printing unit for printing on the recording medium. Next, the web guide element, along with the recording medium, is moved vertically toward the printing unit in an upward motion until the desired printing gap is adjusted. Now, printing can be done on the recording medium.

[0013] The length and tensile stress of the recording medium are modified so that the desired starting position and desired tensile stress on the recording medium are maintained during linear and vertical movements to restart printing. After printing, the web guide unit is moved out of the printing position by linear movement.

[0014] The maintenance unit is moved in a linear motion to a maintenance position below the printing unit for maintenance of the printing unit. Then, the cleaning element and / or protective element are moved in an upward motion toward the printing unit to clean and / or protect the printing unit.

[0015] Such devices and methods have the advantage that only the web guide unit and maintenance unit need to move relatively large distances linearly and in the same direction. These units are moved along a single common guide rail. Larger printing units with multiple supply lines do not need to be moved as they are fixed in position. Furthermore, relatively lightweight elements such as cleaning elements and / or protective elements, as well as web guide elements, can perform short vertical movements independently by separate drive mechanisms, without needing to move the web guide unit or maintenance unit together. Thus, the configuration height of the ink printer can be reduced. Since the ink printer is formed relatively long in any case for ink drying, such length can be well utilized for the horizontal sliding of the web guide unit and maintenance unit. Advantageously, only the lightweight elements are moved in the vertical movement, while the two heavier units (web guide unit and maintenance unit) are moved linearly only in the horizontal direction.

[0016] An advantageous configuration of the present invention is described in the dependent claims. Thus, the web guide unit has one or more web guide elements for guiding the web of a recording medium, and the web guide elements are connected to a lifting device to move the recording medium to a transfer position in the direction of the printing unit for printing mode. Thus, the drive device for the lifting motion can be sized to be minimally small and is independent of the main drive device for the linear movement of the printing unit and the maintenance unit.

[0017] The maintenance unit includes a cleaning device and a cover device, each capable of performing short vertical lifting movements toward the print bar to clean the print head and to protect it with the mountable cover device. In this case, the web guide unit and the maintenance unit do not move together vertically.

[0018] Furthermore, advantageously, the ink printer requires only a relatively small, sized lifting mechanism that can perform each lifting motion independently of linear movement, for the web guide element or cleaning and / or cover device.

[0019] If the cleaning device has a wiper device and, optionally, a spray device, the print head can be wet-cleaned and then wiped dry.

[0020] It is also advantageous if the cover unit is detachably connected to the cleaning unit, and the cover unit and cleaning unit move up and down together, and are only separated from each other when the cover unit is in a resting position and can cover the print head to prevent the nozzles from drying out and remain there. Therefore, it is not necessary to use a separate drive unit for the cover unit.

[0021] If the print bar is formed to move passively, it will move together with the cover and / or cleaning unit in the same direction as the cover and / or cleaning unit's lifting and lowering movements, thereby ensuring that the print head does not enter the movement path of the web guide unit or maintenance unit, and is reliably retracted together with the cover unit into the printing unit in a resting state. Therefore, the print bar does not require its own drive mechanism for lifting and lowering.

[0022] The web guide unit is particularly advantageous if it has a length compensation device, which maintains the desired starting position on the recording medium and the desired tensile stress on the recording medium when restarting printing during the linear movement of the web guide unit. Thus, printing can continue after the cleaning process without interruption (i.e., without printing errors) at the precise desired position (print line).

[0023] Embodiments of the present invention will be described in detail below with reference to schematic drawings. [Brief explanation of the drawing]

[0024] [Figure 1] FIG. showing the ink printer according to the present invention in the printing mode. [Figure 2] FIG. showing the ink printer device in the cleaning mode (purge). [Figure 3] FIG. showing the ink printer device in a state where the print bar is accessible for manual inspection. [Figure 4] FIG. showing the ink printer device in a state where the print bar is in the standby state. [Figure 5] FIG. showing an example of an ink printer device in which the print bars are cleaned (wiped) separately from each other. [Figure 6] FIG. showing an example of FIG. 5 in which one of the print bars is in the standby state and the other print bar is cleaned (wiped). [Figure 7] FIG. showing another example of an ink printer device in which all the print bars are cleaned by one common wiper. [Figure 8] FIG. showing an example of an ink printer device in which additional maintenance is performed on one of the print bars in the cleaning mode. [Figure 9] Flowchart for a method for printing on a web-like recording medium.

[0025] Hereinafter, the present invention will be described in detail with respect to an ink printer formed for two-color printing here. For this purpose, the ink printer has one print bar for each color with one or more print heads capable of printing on a web-like recording medium over the line width. Of course, an ink printer having a larger or smaller number of print bars for a larger or smaller number of colors or inks may be used without departing from the spirit of the present invention. In the drawings, only the essential components important for the functionality of the present invention are shown in detail, and functionally identical or similar elements are denoted by the same reference numerals.

[0026] FIG. 1 shows a first embodiment of an ink printer 10 for printing on a web-like recording medium 11, and the recording medium 11 is conveyed so as to pass through the ink printer 10 in the conveying direction 15 (see thick arrow). The printing unit 12 has two print bars 14 (DR1 and DR2), and these print bars can print on the recording medium 11 line by line. The print bar 14 extends in the lateral direction with respect to the conveying direction 15 over the entire width of the recording medium 11 (in the lateral direction with respect to the conveying direction 15, that is, the line width) so as to print on the recording medium line by line (the extension of the line is in the plane of the drawing in FIG. 1).

[0027] The printing unit 12 is always fixedly arranged within the ink printer 10 and does not move either horizontally or vertically. Only the print bar 14 may have a short vertical lifting distance 16 (see FIG. 2), but as will be described in more detail later, it does not actively move this distance, but is forced to move (i.e., passively) by other elements.

[0028] Below the printing unit 12, a web guide unit (hereinafter referred to as web carriage 20) and a maintenance unit 21 are arranged in a horizontal plane on a common axis. The web guide unit and the maintenance unit 21 can be guided by a guide element (hereinafter referred to as guide rail 22; schematically shown in FIGS. 2 and 3) along the horizontal axis and moved axially (corresponding to a linear movement in the horizontal direction).

[0029] In the embodiment of Figure 1, the web carriage 20 is located directly below the print bar 14 with respect to the horizontal position. Therefore, with respect to the web carriage 20, this position will be referred to below as the horizontal printing position 30. The web carriage 20 has a web guide element which may have one web guide support 23 and one or more web guide rollers 24. The web guide elements 23,24 move the web of the recording medium 11 along its vicinity in the transport direction 15 along the print bar 14 with a substantially constant gap (referred to as the printing gap 25) relative to the nozzle plate. Thus, the recording medium 11 is guided for printing substantially parallel to the nozzle plate of the print head (this may be a straight or curved printing gap 25 in the area of ​​the print bar 14). Thus, the recording medium 11 can be printed line by line in the area of ​​the printing gap 25.

[0030] In the embodiment shown in Figure 1, the maintenance unit 21 is located in the idle position 32. In the idle position, the maintenance unit is retracted until cleaning of the print bar 14 is required or until the protective cover (hereinafter referred to as the cover cap 27) should be placed over the print bar 14. For maintenance, the maintenance unit is moved to a horizontal maintenance position 33 below the print bar 14, that is, to the position where the web carriage 20 was previously located at the print position 30. This will be explained in more detail with reference to Figures 2, 5, 6, 7, and 8.

[0031] The web carriage 20 and the maintenance unit 21 are reciprocated axially only in the same plane (horizontal plane). The web carriage 20 and the maintenance unit 21 are guided by the same linear guide (typically one or more guide rails 22). The web carriage 20 and the maintenance unit 21 are advantageously detachably connected to each other so that they can be moved linearly along the horizontal axis together or independently of each other.

[0032] The web guide support 23 may be firmly connected to a plurality of web guide rollers 24, so that the movement of the web guide support 23 (in the vertical direction) allows the web guide rollers 24, and therefore the web of the recording medium 11, to move together.

[0033] Another transport and deflection element (e.g., a transport or deflection roller 35) guides the recording medium 11 in a loop as it is transported by the web carriage 20 in the transport direction 15 (see arrow in Figure 1).

[0034] In the first embodiment, the lifting device 37 is located below the web carriage 20. The lifting device 37 has a drive mechanism (not shown) which can be mechanically connected to the web guide support 23 via two or more lifting guide rods 38 (indicated in the drawing by elongated dashed double-headed arrows), thereby lifting the recording medium 11 in an upward stroke vertically between the recording medium 11 and the nozzle plate of the print head until a desired height of the print gap 25 is obtained. During the upward stroke, the recording medium 11 is maintained parallel to the plane of the nozzle plate of the print head.

[0035] At least one web guide support 23 is positioned on the side of the web of the recording medium 11 (typically, two web guide supports 23, one on the left and one on the right side of the web, are sufficient). Lifting guide rods 38 are also positioned on the side of the web and surround the recording medium 11 without contacting the recording medium (typically, the lifting guide rods 38 are provided in pairs or multiple pairs for stability and uniform lifting motion). This allows the lifting guide rods 38 acting on the web guide supports 23 to move the recording medium 11 upwards and downwards in a vertical lifting motion.

[0036] Next, printing can be started, during which the recording medium 11 is transported and printed line by line. If the printing process is interrupted for a relatively long period, the recording medium 11 is moved downward again by the lifting device 37 in a downward stroke. The upward and downward strokes are small vertical lifting movements (lifting distance 16; see Figure 2). In this case, the web carriage 20 itself is not moved, and only the web guide elements 23, 24 (including the web guide support 23 and web guide roller 24) that guide and transport the recording medium 11 in the area of ​​the printing gap 25 are moved.

[0037] The lifting guide rods 38, which are mechanically connected to the web guide elements 23 and 24, function to move the web guide elements 23 and 24, and consequently the recording medium 11, vertically during vertical lifting motion. In this case, the lifting guide rods 38 are positioned outside the recording medium 11 (on the sides of the web, respectively) (i.e., in front of and behind the web in Figure 1) so as not to obstruct the transport of the recording medium 11 during the lifting motion.

[0038] The maintenance unit 21 is used for cleaning and protecting the print bars 14 (i.e., the nozzle plates of the print head located within the print bars). The maintenance unit has one cleaning device 40 (CL1 or CL2) for each print bar 14, each equipped with a cover cap 27. The cleaning device 40 and cover cap 27 can be moved in small upward or downward strokes in the vertical direction (perpendicular to the horizontal plane of movement) (the maintenance unit 21 itself is not moved in this case). This upward and downward movement can be achieved by the lifting device 37 as soon as the maintenance unit 21 is in the maintenance position 33, with the web carriage 20 having previously left its printing position 30 and moved to its horizontal resting position 31. In the case of the cleaning device 40 and cover cap 27, the lifting guide rod 38 acts on each element of the maintenance unit 21 (i.e., the cleaning device 40 and / or cover cap 27) to lift or lower these elements in the upward or downward movement.

[0039] Figure 2 shows the maintenance state in which the maintenance unit 21 has been moved a linear distance of 42 (see double-headed arrow) to the maintenance position 33 below the print bar 14. In this operating state (the resting position 31 of the web carriage 20), the recording medium 11 can remain stationary and does not need to be transported further, so the recording medium 11 is in a stationary state (i.e., a resting state, not print mode). However, logically, the transport of the recording medium 11 is always possible.

[0040] The web carriage 20 was moved in advance from the printing position 30 to the resting position 31, so that the maintenance unit 21 could take the maintenance position 33. The maintenance position 33 of the maintenance unit 21 is approximately the same as the printing position 30 of the web carriage 20.

[0041] In the embodiment shown in Figure 2, the maintenance unit 21 is positioned in a maintenance position 33 where the cleaning device 40 and the cover cap 27 have been moved by the lifting device 37 in the direction of the print bar 14 by the amount of the upward stroke. As a result, the cover cap 27 is pressed against the print bar 14 from below, and the print bar 14 is passively pushed further upward by a predetermined small lifting distance 16.

[0042] In this position, the cover cap 27 can be locked in place within the printing unit 12, so that the print bar 14 rests firmly (but again removable) on the cover cap 27. Thus, the cover cap 27 is firmly connected to the print bar 14 and can remain in this resting position (this lifted position of the covered print bar 14 is also referred to as the resting position 39). Therefore, drying of the print head nozzles is prevented.

[0043] In this case, the cover cap 27 is mechanically locked within the printing unit 12 in the resting position 39, so that this position can be held independently without being affected by the force of the lifting device 37.

[0044] Purge is also possible in the resting position 39. In this case, the cover cap 27 may be filled with liquid at least partially to create a high-humidity environment in the nozzle area and prevent the nozzle from drying out too quickly. Filling, rinsing, and emptying the cover cap 27 is preferably done by piping / conduits from above (not shown). These piping / conduits enter the cover cap 27 only as the cover cap 27 moves up and down.

[0045] In this case, the print bar 14 is passively guided without a dedicated drive mechanism and lifted together with the cover cap 27 until the lower surface of the cover cap 27 no longer protrudes from the lower surface of the printing unit 12. In this position, the cover cap 27 is locked within the printing unit 12 via a suitable locking mechanism. Therefore, the lifting and positioning of the print bar 14 by a dedicated motor for the cover cap, which is common in the past, is unnecessary. Consequently, only a very small lifting distance 16 is required, which reduces the overall height of the printing unit 12. Therefore, the lifting device 37 can be sized to be extremely compact, which is advantageous in that it is very light in weight. In this case, the short travel time is particularly important and advantageous.

[0046] For example, the cover cap 27 can be briefly (temporarily) placed over the print bar 14 to flush cleaning fluid or ink through the nozzles under high pressure / to purge the nozzles. The flushed liquid is collected by the cover cap 27 and discharged from there. Thus, components of the ink printer 10 located outside the cover cap 27 are protected from contamination during flushing (purging). The cleaning fluid can also be guided into the print bar 14 and cover cap 27 via a hose or piping and discharged from there by a pump.

[0047] Only one drive mechanism is required for the horizontal axial movement (also called linear movement) of the web carriage 20 and the maintenance unit 21. The two units are not rigidly connected to each other, but are flexibly connected, for example, via electromagnetic or electromechanical locks (not shown in the drawings). This allows the two units to be moved separately from each other or together in the horizontal direction (linear movement).

[0048] The movement ranges of both units are shown in Figure 3, where each unit is shown at its respective horizontal resting positions 31 and 32, which are completely outside the edge of the printing unit 12. For printing mode, the web carriage 20 is moved to the printing position 30 (i.e., the area below the print bar 14, as shown in Figure 1). For maintenance mode, the maintenance unit 21 is moved from the resting position 32 to the maintenance position 33 (i.e., the area below the print bar 14, as shown in Figure 2). The web carriage 20 and the maintenance unit 21 are moved linearly along a straight line by a linear guide rail 22 (also referred to as linear movement or translational motion).

[0049] When the web carriage 20 moves, the movement of the recording medium 11 is blocked at the entrance side (by the retraction motor). During the movement of the web carriage 20, minimal length compensation and tensile stress control along the web of the recording medium 11 must be performed (for example, by an active dancer roller / paper loop or by a torque-controlled pull-out motor). Otherwise, the web may be subjected to excessively high tensile stress and, in the worst case, may tear. Such length compensation compensates for the change in web length from the exit of the ink printer 10 to the print position 30, rather than changing the actual position (line) just after printing, so that when printing is restarted after processing, the correct starting position is again present on the recording medium 11 just below the print bar 14. During processing, a necessary predetermined tensile stress is maintained within the recording medium 11 so that printing can actually be started (or continued) accurately at the desired starting position on the recording medium 11 after sliding. In this case, the accuracy of the starting position positioning is typically in the range of about 20 to 100 μm, depending on the print resolution.

[0050] This length compensation ensures that the actual starting position on the recording medium 11 for restarting printing (the desired new print line is located in a corresponding position within the area of ​​the web guide roller 24 to resume printing) and the tensile stress within the web are maintained. In other words, nearly complete length compensation is achieved as the web carriage 20 moves between the print position 30 and the rest position 31.

[0051] This length compensation and tensile stress compensation are also effective during the lifting motion, as the web must be compensated for its length in this case. In this case, the transport step is delayed so that it can be accurately measured, for example via incremental rollers, and after processing, the precise starting position can be generated again after the movement of the web carriage 20 or web guide elements 23, 24.

[0052] The maintenance unit 21 is located outside the area of ​​the print bar 14 during print mode (i.e., rest position 32). Only when necessary (for maintenance of the print bar 14), i.e., in maintenance mode, the maintenance unit 21 is moved to the maintenance position 33 below the print bar 14.

[0053] When the printing mode is completely finished and the ink printer 10 is turned off, the ink printer 10 enters a dormant state. In this dormant position, as also shown in Figure 4, both print bars 14, along with the inserted / covered cover caps 27, are in a raised vertical dormant position 39, that is, they are outside the printing area (upward stroke) and are positioned higher by a lifting distance 16, so that the covered cover caps 27 do not protrude into the printing gap 25. The print bars 14, which are biased by the upward stroke, are indicated in the drawing by small arrows on the side of the print bars 14. The print bars 14 can remain in the raised position even when the cleaning device 40 is separated from the cover caps 27.

[0054] The web carriage 20 and the maintenance unit 21 are in rest positions 31 or 32, respectively. In this state, the print bar 14 is freely accessible (with or without the cover cap 27). In this rest state, a new recording medium 11 can be more easily inserted into or passed through the ink printer 10. However, in this case, it is desirable that the delicate print head be protected by the cover cap 27. In this state, the print bar is easily and well accessible from below, so the print bar 14 can be easily inspected or replaced manually or visually by a service technician.

[0055] Figures 3 and 4 show an embodiment in which the lifting device 37 is positioned to the side of the print bar 14. A lifting guide rod 38, not shown herein, must be connected in this case to a corresponding element in the web carriage 20 or maintenance unit 21 laterally to the recording medium 11 (i.e., to the side of the web, along the web) and move up and down from the lifting device 37 to these elements in order to lift or lower these elements in small lifting movements. Thus, in this case, lifting movements can be performed without damaging or contacting the recording medium 11 and the print bar 14.

[0056] To clean ink residue or other contaminants from the print head, print head cleaning is performed from time to time or as needed, as shown in Figure 5. In this case, the cleaning device 40 is moved upward by a lifting device 37 (in this case, in front of or behind the print bar 14 in the longitudinal direction) so that the cover cap 27 still has space between itself and the print bar 14.

[0057] First, the print head is purged (through-flow of the nozzles under high pressure), in which case the cleaning solution is collected by the cover cap 27. For this purpose, the cover cap 27 is placed over the print bar 14 as shown in Figure 2. Next, residual ink, cleaning solution, and contaminating particles must be cleaned from the nozzle plate.

[0058] For this reason, the cover cap 27 is moved somewhat downward during the downward stroke, thereby creating a somewhat larger gap with respect to the nozzle plate. Then, one or more wipers 43, each having one elastic wiper blade 44, move along the print bar 14 and enter this space between the nozzle plate and the cover cap 27. In this case, the wiper blades 44 are positioned by the lifting device 37, brought into contact with the nozzle plate, and moved along the longitudinal axis of the print bar 14, wiping the nozzle plate in the process.

[0059] Before wiping, the cleaning solution can be sprayed onto the nozzle plate using the spray nozzle, and any residue will be wiped away in the subsequent wiping process.

[0060] The wiper 43, which has a wiper blade 44, is located at the end of the cleaning device 40 when in a resting state, but is positioned outside the area of ​​the print bar 14 so as not to interfere with or obstruct the lifting motion of the wiper 43. Therefore, the process of covering the print bar 14 with the cover cap 27 is not obstructed.

[0061] To spray the cleaning solution onto the print bar 14, the cleaning device 40 is moved upward to a height that allows the cleaning solution to be effectively sprayed only onto the nozzle plate. In this case, the spray nozzles can be moved from front to back or back to front (i.e., in the line direction) by the same drive mechanism as the wiper 43 to spray the cleaning solution.

[0062] For this reason, the cover cap 27 is not placed over the print bar 14. Consequently, the print bar 14 is not lifted and is directly positioned at the height of the print gap 25.

[0063] During nozzle plate cleaning, the cleaning device 40, together with the cover cap 27, is positioned away from the print bar 14 so that the wiper 43, including the wiper support 45, can travel through the intermediate space by horizontal movement along the print bar 14 (in the line direction) along an appropriate longitudinal guide (in the line direction) to wipe the nozzle plate.

[0064] In this embodiment, the cleaning device 40 and the cover cap 27 can be moved independently of each other during the upward and downward strokes. The cover cap 27 is, of course, removable from each cleaning device 40 and can be placed over the print bar 14, remaining there until the cleaning device 40 is lowered again and reaches the starting position.

[0065] In the embodiment shown in Figure 5, each wiper 43 has a wiper support 45 independent of the other wiper, so that the wipers 43 can be moved independently of each other. Therefore, each wiper support 45 is provided above one cleaning device 40. Thus, each wiper 43 itself can wipe the nozzle plate of each print bar during longitudinal movement along the print bar 14, thereby cleaning it.

[0066] If only one of the print bars 14 (in this case, DR2) needs to be cleaned, and the other (in this case, DR1) is not in operation, the first print bar 14 (DR1) is covered and protected by the cover cap 27 in the rest position 39, as shown in Figure 6. This first print bar 14 (DR1) is forcibly guided upward (by a lifting distance of 16 relative to the second print bar 14 (DR2)) by the lifting motion of the cleaning device 40 (CL1) together with the cover cap 27 until the print bar 14 is reliably rested and the wiper 43 does not come into contact with the cover cap 27 during any wiper motion that may occur. The second print bar 14 is not covered by the cover cap 27 and can be cleaned as usual. For this purpose, the second print bar 14 (DR2) is moved back and forth laterally relative to the longitudinal axis of the print bar 14 (in the line direction) by its associated wiper 43 and cleaning device 40 (CL2), and in this case, the nozzle plate is cleaned by blowing and wiping, if necessary.

[0067] Figure 7 shows an embodiment in which both wiper blades 44 are arranged together on a single common wiper support 45. The wiper support can similarly move in the line direction along guide rails along the cleaning device 40. The wiper support 45 is located above both cleaning devices 40 and is moved along the print bar 14 during the wiping process so that both wiper blades 44 contact the nozzle plate, while the wiper support 45 does not contact the cleaning device 40, as contact with the cleaning device would damage it. Thus, the print bar 14 can be cleaned together by wiping (and possibly pre-spraying) in a single movement. Thus, one drive unit (or multiple drive units if there are more than two print bars 14) (and possibly one or more guide rails) is omitted compared to a wiper 43 that can move independently, i.e., both print bars 14 are cleaned simultaneously in a single process. Even separate wipers 43 can be moved simultaneously.

[0068] Therefore, cleaning of individual print bars 14 by a central common wiper support 45 functions as effectively as having one wiper support 45 for each wiper 43. The cover cap 27 extends directly below the print bars 14 and is formed to open upwards like a tank, so that used cleaning fluid is collected in both cases within the cover cap 27. The collected liquid is then discharged from here (for example, when the print bars 14 are idle) by a pump, for example, and discarded or reused. Therefore, no additional container for used cleaning fluid is required. Consequently, the space required for implementing the cleaning function is also minimal compared to a conventional cover cap 27.

[0069] With respect to the nozzle plate, the height position of the wiper blade 44 can be arbitrarily adjusted by the upward and downward movement of the cleaning device 40 by the lifting device 37. This allows the wiper 43 to be moved toward the nozzle plate with more or less pressure, or gently, and at the end of the process, it can be gently removed from the wiper 43 without scattering the cleaning fluid located on it.

[0070] The embodiment shown herein saves configuration space, allowing additional functions to be implemented in the ink printer 10, as exemplified in Figure 8. In Figure 8, the maintenance unit 21 is formed to be somewhat elongated, leaving internal space for further installation, which is used for one or more additional devices or for special maintenance devices 47(SF). The maintenance devices 47 can implement extended maintenance functions, such as the use of a camera system for nozzle inspection, or special printhead cleaning in the form of flash cleaning of the nozzle plates with cleaning fluid, or cleaning with a fleece strip. The camera system can also advantageously check printhead alignment.

[0071] In this case, the first print bar 14 (DR1) is in the rest position 39, and the second print bar 14 (DR2) is not lifted and is not covered, so that in this case a suitable print head can be serviced by a special maintenance device 47.

[0072] In the embodiment shown in Figure 8, only the second print bar 14 (DR2) is equipped, while the first print bar 14 (DR1) is located in the rest position 39 and is covered by the cover cap 27.

[0073] Figure 9 shows a method of printing on a recording medium 11 by an ink printer 10. In this case, in step S1, the web carriage 20 is moved linearly to a printing position 30 below the printing unit 12 in order to print on the recording medium 11. Then, in step S2, the recording medium 11 is moved toward the printing unit 12 in a vertical motion by web guide elements 23, 24 until the desired printing gap 25 is adjusted. During this vertical motion, in step S3, length compensation and tensile stress compensation are performed on the recording medium 11 so that printing can be restarted at the precise and desired line position.

[0074] To service the printing unit 12, in step S4 the web carriage 20 is moved linearly from the printing position 30 to the resting position 31. For this purpose, in step S5 the maintenance unit 21 is moved into the maintenance position 33 in the subsequent transfer area to service the print bar 14. In a small lifting motion, in step S6 the cleaning device 40 is moved toward the print bar 14 so that the nozzle plate of the print head can be cleaned. If the print bar 14 is inactive for a relatively long period of time, in a so-called resting state, the print bar is covered and protected by the cover cap 27 to prevent the nozzles from drying out. The cover cap 27 is placed over the print bar 14 by the maintenance unit 21 through a lifting motion toward the print bar 14.

[0075] When it is necessary to print on the recording medium 11 again, the maintenance unit 21 is moved out of the maintenance position 33, and at the same time, the web carriage 20 is moved into the printing position 30, and the web carriage 20 is lifted slightly in the direction of the print bar 14. As the web carriage 20 moves in a straight line in the horizontal direction, length compensation and tensile stress compensation for the recording medium 11 are also performed.

[0076] With such an ink printer 10 equipped with a fixed-position printing unit 12, large, flexible conduits are no longer required for supplying ink to the print head. Furthermore, since the print bar 14 no longer moves (except for small vertical movements), all conduits and hoses can be made shorter. Also, since there is no need to guide flexible cables, pneumatic or hydraulic conduits over relatively long distances, drag chains are also unnecessary.

[0077] The web carriage 20 and maintenance unit 21 have significantly reduced weight compared to conventional ink printer heads. This allows the components to move more quickly, for example, from print mode to cleaning mode. Furthermore, the web carriage and maintenance unit are moved along only one horizontal axis, thereby reducing the complexity of their drive mechanisms. This saves a large amount of configuration space, particularly in height, of the ink printer 10.

[0078] Furthermore, since only a very short lifting distance 16 is required to place the cover cap 27 over the print bar 14, the time required for this can be reduced. In addition, because the print bar 14 is passively lifted by the maintenance unit 21, a drive mechanism suitable for moving the print bar 14 vertically is omitted. The short lifting distance 16 has the advantage of not requiring a dedicated drive mechanism, and only requiring a short length and guide drive mechanism. The space gained increases the structural freedom for the printing unit 12 and the ink printer 10 as a whole.

[0079] The web carriage 20 and the maintenance unit 21 can be moved separately, allowing them to be moved laterally outwards. This provides free access to the area of ​​the print bar 14, including the nozzle plate, making manual inspection of the print unit 12 easier. This also facilitates the rearrangement of the modular components in the ink printer 10.

[0080] If the recording medium 11 moves up and down vertically, this allows for quick and easy adjustment of the height of the print gap 25 without the need to re-adjust the entire print unit 12. Furthermore, it is not necessary to move the entire web carriage 20 vertically to adjust the print gap 25.

[0081] Adaptation to the thickness of the recording medium 11 is also easily possible so that a predetermined print gap 25 is always adjusted to its height. Preferably, the height of the print gap 25 is 0.8 mm to 1.4 mm; very preferably, it is about 1 mm to about 1.2 mm. To prevent damage to the print head by contact with the print head, the rapid lowering or raising device 37 of the web guide elements 23, 24 expands the print gap 25, allowing for very rapid response to any raised or adhered areas that may be present on the recording medium 11. The upward and downward movement of the cleaning device 40 and the cover cap 27 ensures the precise and rapid positioning of the cover cap 27 for the print bar 14, wiper 43, and spray device, and optionally for any new or additional cleaning functions. Only a few conduits and hoses are required for actuators and / or sensors that may be present in the web carriage 20 and maintenance unit 21, for example, for cleaning fluid. Such hoses or conduits can be guided by small, lightweight drag chains.

[0082] There is no need to actively move the print bar 14 upward or downward. Only passive movement is possible, starting from the cleaning device 40 or the cover cap 27, which forces the print bar 14 to move when the cover cap 27 is placed over the print bar 14. The lifting distance 16 is extremely short, approximately equal to the height of the cover cap 27. This positions the idle print bar 14 upward, along with the inserted cover cap 27, so as not to interfere with the cleaning of another print bar 14 or the transport of the recording medium 11. Because the lifting movement is passive and extremely short, a large amount of space is saved in the area of ​​the printing unit 12 compared to a conventional ink printer 10 (with a resting flap).

[0083] Movement can be carried out by electromechanical or hydraulic lifting devices 37, or by drive devices for linear movement. The lifting devices 37 may be located within the maintenance unit 21, within the web carriage 20, within the printing unit 12, or outside these elements, respectively. Since the web carriage 20 and the maintenance unit 21 move only in the horizontal axial direction, a single common lifting device 37 for the web carriage 20 and the maintenance unit 21 can be located below their range of movement.

[0084] Therefore, the lifting device 37, which includes the lifting guide rod 38, may be formed in a substantially U-shape. This allows the cleaning device 40, which includes the web guide elements 23, 24 including the web guide support 23 and the cover cap 27, to be moved vertically together or separately from each other in an upward or downward stroke, so that the lifting guide rod 38 moves outside the recording medium 11 during the upward or downward movement.

[0085] The first lifting motion occurs as soon as each unit (web carriage 20 and maintenance unit 21) is positioned at the printing position 30 or maintenance position 33. Subsequently, each web guide element 23, 24 or cleaning device 40 / cover cap 27 can be moved up and down via the lifting guide rod 38. The lifting motion can be performed separately for each unit (web guide elements 23, 24, cleaning device 40, and cover cap 27). The cleaning device 40 and cover cap 27 can also be moved vertically together by a single drive unit. To place the cover cap 27, the cover cap must be lifted together with the print bar 14 and cleaning device 40. The drive unit should not be overly small in size, as a powerful reducer may be required to slow down the lifting process in some cases, given the weight, which is not always light.

[0086] The lifting device 37 may also be positioned within the printing unit 12, to the side of the print bar 14, so that the cover cap 27 or cleaning device 40 can move up and down without obstructing the horizontal linear movement of the web carriage 20 and the maintenance unit 21. The lifting device 37 may also be positioned within the printing unit 12, in front of or behind the print bar 14, outside the width of the recording medium 11, to move the cover cap 27 or cleaning device 40.

[0087] The web carriage 20 and the maintenance unit 21 may each have their own internal lifting device 37. However, this would make the structure of both units more complex and thus more costly than linear movement. Therefore, the lifting device 37 is preferably located outside the stationary parts.

[0088] Elements intended for lifting and lowering motion can also be moved by a single common lifting device 37, for example, as shown in Figures 1 to 8. This reduces the need for multiple individual lifting mechanisms and position sensors within the web carriage 20 and the maintenance unit 21. This minimizes the need for wiring and flexible conduits.

[0089] The lifting device 37 can be implemented by an electric motor equipped with a transmission, drive screw, eccentric body, and rope, or by a hydraulic / pneumatic cylinder equipped with a corresponding guide (rod, rail, rack, wedge, etc.). A lifting device 37 that moves the unit vertically is also possible using a mechanical cam track, but its flexibility and functionality are somewhat limited.

[0090] The web carriage 20 and the maintenance unit 21 are moved along a straight line by a linear guide (guide rail 22) (translational motion, linear movement). Both units can be moved together by such a translational or linear guide as a mechanical guide. However, a flexible variable coupling may be placed between the web carriage 20 and the maintenance unit 21 (not shown in the drawings), which allows both units to be moved horizontally separately or together. Therefore, since only one of the two units can always be positioned below the print bar 14 when the ink printer 10 is in operation, both units can be moved by a single drive mechanism when they are coupled together.

[0091] In such special cases, a second drive unit is not necessary. However, for example, in order to visually inspect the print head, it is desirable that the area below the print bar 14 be open, and consequently, that neither unit be positioned below the print bar 14 (as shown in Figure 3, for example). In this case, both units (web carriage 20 and maintenance unit 21) must also be movable independently of each other.

[0092] For translational motion, a guide system can be used in which one or more guide carriages travel along one or more long, mostly straight bodies (guide rails 22) whose positions are fixed. For simplicity, the guide rails 22 are usually paired, adjacent to each other and positioned below the unit to be moved horizontally, and the guide rails 22 and the unit are assembled to be slidable from each other, mainly (such as upper and lower parts).

[0093] As the lifting guide rod 38, any suitable element such as a spindle, rack, rope, etc. can be used to fully perform translational lifting motion or to convert rotational motion into linear motion.

[0094] The length compensation device is not shown in detail in the drawings. However, such a length compensation device may be part of the transport device for the recording medium 11. Transport must be controlled with extreme precision in order to print the printed image in the correct position. In this case, all movement of the web (forward movement and possible backward movement) is always measured with extreme precision by a suitable incremental encoder, for example, on the transport roller. In any case, the drive device to be controlled is configured with extreme precision in order to measure the movement in the micrometer range and control the desired transport drive device accordingly. Furthermore, since the dimensions in the ink printer 10 are known with extreme precision, the length compensation device can be used very effectively to control the transport device. [Explanation of Symbols]

[0095] 10 Ink Printers 11 Recording media 12 printing units 14 Print Bar 15. Direction of transport of recording medium 16. Lifting distance 20 Web Carriage (Web Guide Unit) 21 Maintenance and Repair Unit 22 Guide rails (guide elements for linear movement) 23,24 Web Guide Elements 23 Web Guide Support 24 Web Guide Laura 25 Printing gap 27 Cover cap (cover device) 30 Print position 31. Rest position of the web carriage 32. Stopping positions of maintenance and repair units 33 Maintenance and Repair Locations 35 Conveyor roller or direction change roller 37 Lifting device 38 Lifting guide rod 39. Print bar rest position 40 Cleaning device 42. Straight-line distance traveled 43 Wiper 44 Wiper Blades 45 Wiper support 47 Additional equipment

Claims

1. An ink printer for printing on a web-like recording medium (11), comprising: a printing unit (12) comprising at least one printbar (14) with one or more printheads for printing ink colours, the printing unit (12) being arranged in a fixed position within said ink printer (10); - a web guide unit (20) movable along one axis for guiding said recording medium (11), said web guide unit (20) being arranged below said printing unit (12) so as to be linearly movable along a guide element (22); a servicing unit (21) movable along one axis for servicing said printing unit (12), which is likewise arranged below said printing unit (12) so as to be linearly displaceable along said guide element (22); It has - said web guide unit (20) is positioned in a printing state below said printing unit (12) in the region of said print bar (14) and said servicing unit (21) is positioned in a servicing state in the region of said print bar (14), - an ink printer, wherein said web guide unit (20) and said maintenance unit (21) are removably mechanically connected to each other and can be linearly moved independently of each other or together along said guide element (22) in the horizontal direction.

2. 2. The ink printer of claim 1, wherein the web guide unit (20) has one or more web guide elements (23, 24) connected to a lifting device (37) for moving the recording medium (11) in a lifting motion towards the printing unit (12) for the printing mode.

3. 3. The ink printer of claim 2, wherein the maintenance unit (21) has at least one cleaning device (40) and at least one cover device (27), the cleaning device (40) and the cover device (27) being connected to a lifting device (37) for moving the cleaning device (40) and / or the cover device (27) together or separately in a maintenance mode towards the printing unit (12) for maintenance.

4. 4. The ink printer according to claim 3, further comprising a common lifting device (37) arranged below the web guide unit (20) and the maintenance unit (21), the lifting device having a lifting element (38) which is moved vertically laterally of the recording medium (11) in order to perform respective lifting movements for the web guide elements (23, 24), the cleaning device (40) and / or the cover device (27).

5. An ink printer as claimed in claim 3 or 4, characterized in that the cleaning device (40) comprises a wiper device (43, 44, 45) and possibly a spray device for cleaning the printhead.

6. 5. The ink printer of claim 4, wherein the cover device (27) is removably connected to the cleaning device (40), and the cover device (27) covers the print head in a rest state to protect the nozzles from drying out.

7. 7. The ink printer according to claim 6, wherein the cover device (27) is mechanically locked within the printing unit (12) so that, in a rest state (39), its position is held autonomously without the influence of force from the lifting device (37).

8. 5. The ink printer according to claim 3, wherein the print bar (14) is passively movable in the vertical direction and is forcibly guided and moved together in the same direction by the raising and lowering movement of the cover device (27) and / or the cleaning device (40).

9. 5. The ink printer according to claim 1, wherein the web guide unit (20) has a length compensation device, and the length compensation device is controlled such that a desired starting position on the recording medium (11) for restarting printing and a desired tensile stress in the recording medium (11) are maintained during linear movement of the web guide unit (20).

10. 1. A method of operating an ink printer for printing on a web-like recording medium (11) with ink, comprising the steps of: - moving the web guide unit (20) by a linear movement into a printing position (30) below the printing unit (12) for printing on said recording medium (11), then moving the web guide elements (23, 24) by a lifting movement vertically towards said printing unit (12) until the desired printing gap (25) is adjusted, in which case the length and the tensile stress of said recording medium (11) are modified during said linear movement and during said lifting movement such that a desired starting position and a desired tensile stress on said recording medium (11) for restarting printing are maintained, - moving the web guide unit (20) out of the printing position (30) after printing, after lowering of the recording medium (11) and the subsequent linear movement of the web guide unit (20), - moving a maintenance unit (21) in a linear movement below said printing unit (12) to a maintenance position (33) for maintenance of said printing unit (12), and then moving cleaning and / or protective elements (27, 40) in an up-down movement towards said printing unit (12) for cleaning and / or protecting said printing unit (12).

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