Deformation compensation system for digital printing systems

Abstract

A digital printing system for printing on a substrate comprising: at least one printhead mount, at least one printhead module supported by the printhead mount, one or more support structures configured to support the printhead mount, at least one compensation system configured to prevent deformation of the at least one printhead mount. The at least one printhead mount has an elongated body with a length greater than 2 meters spanning the width of the substrate.

Description

DEFORMATION COMPENSATION SYSTEM FOR DIGITAL PRINTING SYSTEMSThe present invention relates to the field of digital printers, and more particularly to large- scale printers, such as single pass inkjet printers, used primarily for commercial and industrial high resolution printing applications. An aspect of the invention relates to a digital printing system. This digital printing system comprises at least one printhead mount with a predetermined length, one or more print heads, and a compensation mechanism designed to correct any deformations of the printhead mount.BACKGROUND

[0001] Digital printers are versatile tools for generating printed images across a diverse array of media. They are capable of printing on various receivers, often referred to as imaging substrates or recording media. Digital (inkjet) printers often have one or more print head modules for dispensing ink onto a print substrate like paper, plastic, or other materials. Each of these print head modules adds weight and stress to the mechanical parts of the printer, especially the print bar (in single-pass printers as well as in multi-pass printers and optionally the driving shaft in case the print bar moves (such as in multi-pass printers).

[0002] These mechanical stresses are particularly pronounced in industrial scale printing operations. In large-scale printing, where digital printers often feature components such as a print bar extending beyond 2 meters, several challenges may arise. These challenges primarily stem from the structural and mechanical demands placed on such large-scale components. One significant issue is the bending (deflection) of the print bar, which can be attributed to the structural load on a print bar of this length which is substantial. If the print bar is not constructed from materials with adequate strength and rigidity or if the ‘section’ of the print bar is insufficient, it can succumb to this load, leading to bending or sagging. As more printhead modules are added, the print bar may need to be reinforced to support the weight without flexing or bending.Excessive weight can potentially affect the accuracy of the print alignment if the print bar flexes or if there is insufficient rigidity, leading to print quality issues such as misalignment or uneven ink deposition. Also, larger print bars, while offering increased capacity, present a growing challenge regarding deflection (bending) due to their increased weight.For example, when the p rint bar is very long (e.g., over 2 meters, or over 3 meters or even over 4 meters) and subjected to high loads, it can bend significantly, with deflection potentially ranging from as little as 0.5 % to as much as 99 % of the jetting distance. This is not desirable, and efforts should be made to minimize deflection to maintain precision in printing.

[0003] In both multi-pass and single-pass printing, these problems are particularly critical. In multi-pass printing, the print head moves back and forth multiple times, increasing the mechanical stress and the likelihood of vibrations affecting print quality. In single-pass printing, the need for high-speed precision makes the print bar's rigidity and stability even more crucial.

[0004] A known solution to address the problem of deflection in print bars involves providing a reinforcement to the print bar or using stronger materials for the print bar. However, the disadvantage of these solutions is that they entail building larger and heavier equipment. Another disadvantage of building larger equipment is that the colour-to-colour registration becomes more challenging, leading eventually to extra print defects.

[0005] It is an aim of the present invention to find a digital printing system configuration that can mitigate deflection and other related issues without necessitating bulkier and heavier components.BRIEF SUMMARY

[0006] The present invention addresses the issue of deflection(s) and vibrations during the printing operation, particularly in industrial-scale digital printers, by implementing a compensation system that corrects or adjusts for potential deflections of the printhead mount. Additionally, the system can involve selecting an optimal cross-sectional shape or profile, size, and material to maximize the moment of inertia (I). This can ensure the printhead mount achieves the necessary stiffness and stability for industrial-scale printing operations.

[0007] Aspects and embodiments of the invention provide a digital printing system, as claimed in the appended claims.

[0008] According to an aspect of the present invention, there is provided a digital printing system for printing on a substrate comprising: at least one printhead mount, at least one printhead module supported by the printhead mount, one or more support structures configured to support the printhead mount, at least one compensation system configured to prevent deformation of the at least one printhead mount.

[0009] According to an aspect of the present invention, there is provided a digital printing system for printing on a substrate comprising: at least one printhead mount, at least one printhead module supported by the printhead mount, one or more support structures configured to support the printhead mount,at least one compensation system configured to prevent deformation and / or vibration of at least one printhead mount, wherein the compensation system comprises at least two compensation mechanisms, arranged symmetrically on opposite outer sides of the printhead mount.

[0010] The digital printing system comprises compensation mechanisms configured to operate in coordination to counteract mechanical disturbances affecting the printhead mount, including displacement, deformation, or vibration.

[0011] Advantageously, in the digital printing system of the present invention, each compensation mechanism is positioned outside an outer vertical side surface of the printhead mount, extending along Z-axis and facing outward along X-axis.

[0012] Advantageously, the digital printing system of the present invention comprises a plurality of printhead mounts arranged sequentially along a substrate feed direction (Y axis), and wherein a distance between each pair of consecutive printhead mounts (also referred to herein as the first and second printhead mounts) along the Y-axis is determined by the physical width of the printheads mounted on the consecutive printhead mounts (first and the second printhead mounts) and a defined separation gap, and wherein no components of the compensation system are positioned between or above the consecutive printhead mounts (first and second printhead mounts), for example, along the Z axis, or extending over the printhead mounts along the X-axis.

[0013] Further, the digital printing system of the present invention may comprise a plurality of printhead mounts positioned consecutively along the Y-axis, corresponding to the media feed direction of the substrate, and spaced apart by a distance I, which defines the spacing between two consecutive printheads mounted on different printhead mounts. Two such consecutive printhead mounts may be referred to herein as a first printhead mount and a second printhead mount, arranged sequentially along the Y-axis.

[0014] Further, the distance (I) between a first printhead mount and second printhead mounts along the Y-axis is defined by the physical dimensions of the printheads mounted thereon, together with a minimal clearance required to prevent physical interference, and without additional spacing introduced by components of the compensation system.

[0015] For example, the printhead mount can be a print bar, having an elongated body with a length greater than 2 meters spanning the width of the substrate. The printhead mount has an elongated body that extends along the X-axis, which spans the width of the substrate and defines its longitudinal direction. The printhead mount includes opposite (opposing) side surfaces located on either lateral side of this axis X, i.e . , the left and right vertical side faces when viewedin a top-down orientation. These opposite sides extend in a direction along the Z-axis to the print direction and are oriented outwardly toward the side frame structures of the printer. In certain embodiments, pivot mechanisms and associated compensation elements, such as springs or dashpots, are mounted to or act upon these opposite side su rfaces to provide balanced mechanical support and symmetrical damping.

[0016] This elongated body may comprise metal or a fibre- reinforced polymeric material. For example, the fibre-reinforced material may be a natural fibre- reinforced polymeric material, or a carbon-fibre reinforced polymeric material, or a glass-fibre reinforced polymeric material. Alternatively, the elongated body of the printhead mount may comprise metal that is selected from the group consisting of aluminium, aluminium alloy, steel, steel alloy, titanium, or titanium alloy.

[0017] In an embodiment, the length of the printhead mount is greater than 2 m, or greater than 3 m, or greater than 4 m, or greater than 5m.

[0018] The printhead mount supports the at least one printhead module, which may include a printhead adapted to carry out printing.

[0019] Further, each printhead module may comprises a printhead adapted to carry out printing and having a plurality of nozzles, wherein a distance between the nozzles and the substrate is defined as a jetting distance. Further, the jetting distance can be in the range of from 0.1 mm to 5 mm.

[0020] Furthermore, the digital printing system of the present invention comprises a compensation system, where the compensation system can be configured to prevent elastic deformation of the printhead mount, where such elastic deformation may manifest as deflection or bending. Further the elastic deformation includes one or more types of deflections that define a total deflection. The term "total deflection" refers to the cumulative displacement of the printhead mount under load, considering all types of deflections occurring along various axes (X, Y, and Z). The total deflection includes contributions from maximum deflection, axial deflection, vertical deflection, and lateral deflection, representing the overall deformation experienced under applied loads. The maximum deflection refers to the greatest displacement experienced by the printhead mount from its original position under a given load or force, occurring specifically at the midpoint x=L / 2 of the printhead mount. Further, this bending or deflection can occur due to the forces exerted by the printhead module(s) and other components, or the weight of the print bar itself, or also due to vibration during operation, or changes in temperature, leading to a change in the structural alignment of the print bar over its length, thereby influencing the jettingdistance. These forces can act in the X, Y or Z directions. Therefore, the compensation system is configured to counteract the total deflection along one or more of the X, Y, and Z axes, and also configured to counteract vibration

[0021] In an embodiment, the digital printing system comprises a compensation system that is configured to counteract the total deflection along at least two directions (X, Y, or Z-axis), preferably along both the vertical (Z-axis) and horizontal (Y-axis) directions. For example, Figures 6 to 9 illustrate this specific configuration of the digital printing system.

[0022] Furthermore, the total deflection is maintained below specific thresholds relative to the jetting distance through the compensation system employed in the present invention. For example, the total deflection (including the maximum deflection) can be less than 90 %, preferably less than 50 %, more preferably less than 20 % of the jetting distance, or less than 15 % of the jetting distance, preferably less than 10 % of the jetting distance, more preferably less than 5 % of the jetting distance, or even more preferably less than 3 % of the jetting distance, or less than 2 % of the jetting distance.

[0023] In an embodiment, the total deflection is less than 90 % of the jetting distance, preferably less than 50 % of the jetting distance, more preferably less than 20 % of the jetting distance, even more preferably less than 10 % of the jetting distance.

[0024] In an exemplary embodiment, the maximum deflection is less than 90 % of the jetting distance, preferably less than 50 % of the jetting distance, more preferably less than 20 % of the jetting distance, even more preferably less than 10 % of the jetting distance.

[0025] Advantageously, the ratio between maximum deflection and the jetting distance can be between 0.002 and 0.9.

[0026] The digital printing system may further comprise a substrate transport system.

[0027] The compensation system of the present invention may further comprise at least one pivot mechanism

[0028] The pivot mechanism can be a hinge pin. The hinge pin is for example a cylindrical rod or shaft that acts as a pivot mechanism and that defines a rotational axis in a hinge mechanism, allowing two connected parts to rotate relative to each other. The hinge pin may be supported within aligned openings or brackets on the support structure or frame. The hinge pin may be configured to translate the deformation of the printhead mount into rotational movement around the hinge pin itself.

[0029] The pivot mechanism may as well be a pivot point or a fulcrum. The pivot mechanism may as well be regarded as a structural node within the compensation system, serving as apivotal connection point that facilitates the distribution of loads, forces, or movements throughout the structure.

[0030] Unless otherwise stated, the structural and functional details described above for a single compensation mechanism apply equally to each compensation mechanism in a system comprising two or more such mechanisms, for example positioned symmetrically on opposite sides of the printhead mount.

[0031] The compensation system of the digital printing system may comprise one or more first and one or more second compensation mechanisms. Further, the at least one or each compensation mechanism can be a passive compensation mechanism and / or active compensation mechanism. Additionally, the one or more first and the one or more second compensation mechanisms can be a first and second elastic elements, such as springs, spindles, or pretensioned bars, or combination thereof, each configured to counteract at least one force exerted by the at least one printhead on the print bar. Each spring may be connected to the hinge pin, which is configured to translate the deflection(s) of the print bar to the first and second springs. These springs, in turn, counteract and correct the deflection(s) to maintain the print bar within specified deflection limits.

[0032] Alternatively, the first and second compensation mechanisms can be a hydraulic cylinder, or a combination of hydraulic cylinders and spring. Another alternative for the first and second compensation mechanisms is the use of spindles.

[0033] Alternatively, the first and second compensation mechanisms can be a dashpot or a combination of one or more dashpots and one or more springs. Dashpots are mechanical damping devices configured to resist motion through viscous dissipation of energy. The dash pot can reduce velocity, vibration, and oscillation in dynamic mechanisms. This is for example accomplished by using a piston to force ambient air or oil through an orifice at a controlled rate to dissipate kinetic energy.

[0034] Another alternative for the first and second compensation mechanisms can be the use of pretensioned bars, or a combination of pretension bars and hydraulic cylinders, or a combination of pretension bars and dashpots.

[0035] Another alternative for the first and second compensation mechanisms can be the use of temperature-actuated bars, or combination of temperature-actuated bars and elastic elements, hydraulic cylinders, dashpots.

[0036] Further, the compensation system may further comprise a control system configured to automatically adjust the at least one compensation mechanism.

[0037] The deflection ratio is defined as the maximum deflection in mm over the printhead mount (print bar) length in mm.

[0038] In an embodiment, the maximum deflection of the print bar is between about 0.01 to 0.5 mm.

[0039] In an embodiment, the digital printing system is a single-pass inkjet printer or multi-pass inkjet printer.

[0040] In an embodiment the inkjet printing method is a single pass inkjet printing method which is preferably performed by an industrial single pass inkjet printing system or preferably performed by an industrial multi pass inkjet printing system in a single pass inkjet printing mode. Printing a pattern in a single pass, gives a boost to the manufacturing time of decorative workpieces which is an economical advantage for a decorative workpiece manufacturer.

[0041] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend on and / or incorporate any feature of any other claim although not originally claimed in that manner.TERMS AND DEFINITIONS

[0042] The term "digital printing" refers to methods of printing from a digital-based image directly to a variety of substrates. Examples of digital printing techniques include inkjet printing and laser printing.

[0043] The term "Inkjet printing" is a digital printing technique known in the art that recreates a digital image by propelling droplets of a colorant, for example, an ink onto a substrate. Typically, printheads using e.g. piezoelectric crystals are used to deposit the droplets on the substrate. Generally, there are two main technologies in use in contemporary inkjet printing processes: continuous (CIJ) and Drop-on-demand (DOD).

[0044] The term “printhead” specifically refers to a component that includes the nozzle plate comprising a nozzle (s) and ink chamber, among other integral parts, designed for dispensing ink onto a substrate.

[0045] The term 'printhead module' encompasses both printhead-related components and additional elements mounted on the print bar, including, but not limited to, the printhead itself, ink supply mechanisms, driver boards, filters, cabling, safety mechanisms, sensors, and fasteners such as nuts and bolts. The terms “print bar” or “print beam “are used herein interchangeably.

[0046] The terms “printing substrate” and “substrate” or “printing medium” are used herein interchangeably. The substrate is the material being printed on.

[0047] The term "jetting distance" refers to the distance between the nozzle of the printhead and the substrate.

[0048] The term "horizontally aligned" herein refers to the print bar being positioned in a horizontal orientation, parallel to the ground, and evenly aligned across the support elements.

[0049] The term “deflection” refers to the displacement of a structural element due static loads (like weight or pressure) and dynamic influences (such as those from environmental vibrations) . The term 'deflection' herein refers to any type of deflection of the printhead mount, including the maximum deflection.

[0050] The term “total deflection” also referred to herein simply as a deflection, is the sum of various types of deflections of the printhead mount, including for example a maximum deflection.

[0051] The term "defined separation gap" refers to a predetermined physical spacing between adjacent printheads or printhead mounts, which is sufficient to allow safe mounting, operation, and thermal or mechanical tolerance without causing physical contact between compone nts.

[0052] The term “maximum deflection” refers to the greatest displacement experienced by the printhead mount from its original position under a given load or force, occurring specifically at the midpoint x=L / 2 of the printhead mount. This displacement represents the maximum extent to which the printhead mount can deflect under the specified conditions.

[0053] The term “long print bar” or “long printhead mount” refers to a print bar with a length exceeding 2 meters and can typically exceed lengths of 3 meters or more, such as 4 meters or beyond.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0054] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0055] FIG. 1 illustrates a side view of a state-of-the-art single pass inkjet digital printing system.

[0056] FIG. 2 illustrates an aspect of the subject matter in accordance with one embodiment, providing a perspective view (front view) of a digital printing system, featuring a first and a second compensation mechanisms with elastic element such as springs.

[0057] FIG. 3 illustrates an aspect of the subject matter in accordance with one embodiment, providing a perspective view (front view) of a digital printing system, featuring one or more first and one or more second compensation mechanisms with hydraulic cylinders.

[0058] FIG. 4 illustrates an aspect of the subject matter in accordance with one embodiment, providing a perspective view of a digital printing system, which includes a combination of springs and hydraulic cylinders (250) as part of its compensation mechanisms.

[0059] FIG. 5 illustrates an aspect of the subject matter in accordance with one embodiment, providing a perspective view of a digital printing system, featuring one or more first and one or more second compensation mechanisms with spindles (450).

[0060] Fig. 6 illustrates an aspect of the subject matter in accordance with one embodiment, providing a front view of the digital printing system, exhibiting downward deflection(s) of the printhead mount.

[0061] Fig.7 illustrates an aspect of the subject matter in accordance with one embodiment. , providing a front view of the digital printing system according to the present invention, after correction of the deflection(s) shown in Fig. 6.

[0062] Fig. 8 shows a top-down view of the digital printing system, illustrating the deflection(s) of the printhead mount in the Y direction (along Y-axis) due to forces such as vibrations.

[0063] Fig. 9 shows a top-down view of the digital printing system, illustrating corrected deflection(s) after the deflection(s) shown in Fig. 8.

[0064] Fig. 10 illustrates an aspect of the subject matter in accordance with one embodiment, providing a side view that specifically shows a plurality of first compensation mechanisms.DETAILED DESCRIPTION

[0065] The present disclosure presents a digital printing system, such as inkjet printer, comprising a compensation system that prevents deformation of the at least one printhead mount during printing on substrate.

[0066] The aim of the present invention is to achieve a consistent and precise jetting distance between the printhead and the printing surface across the entire width of the substrate or printing medium) in large-scale industrial digital printing systems, thus solving the problem of variable jetting distance caused by the deformation of the print bar, particularly where the printhead mount exceeds 2 meters in length.This problem is addressed by the digital printing system in accordance with the present invention. In an aspect of the present invention, there is provided a digital printing system for printing on a substrate comprising: at least one printhead mount, at least one printhead module supported by the printhead mount, one or more support structures configured to support the printhead mount, at least one compensation system configured to prevent deformation of the at least one printhead mount.

[0067] Further, the compensation system is a double or dual compensation system, including at least two compensation mechanisms (first and second compensation mechanisms) positioned on opposite sides of the printhead mount and configured to operate in coordination to provide synergistic compensation for deflection, deformation, or vibration of the printhead mount.

[0068] Further, the two compensation mechanisms (first compensation mechanism and the second compensation mechanism) are preferably identical in structure and function, thereby ensuring symmetrical performance within the compensation system .

[0069] Each compensation mechanism may comprise a spring, a dashpot, or a combination thereof, and is configured to apply restoring and / or damping forces not only in translational directions but also in rotational degrees of freedom. This enables the compensation system to counteract torsional deformation or angular misalignment of the printhead mount. When the compensation mechanisms are identical and symmetrically arranged, they provide balanced and uniform damping or restoring action, enhancing stability and printhead alignment accuracy.

[0070] Thus, each compensation mechanism complements the action of the other to more effectively maintain the structural stability and alignment of the printhead mount, and the two mechanisms are configured to act simultaneously to provide coordinated compensation.

[0071] Thus, the two compensation mechanisms ensure symmetrical response to both translational and rotational disturbances, improving printhead mount stability.

[0072] The compensation system (or the double compensation system) of the present invention may preferably comprise two or more pivot mechanisms, or two or more rotational mechanisms, arranged symmetrically on opposite sides of the printhead mount.

[0073] For example, two such pivot compensation mechanisms may be arranged symmetrically on opposite sides of the printhead mount, specifically on opposite outer vertical side surfaces of the printhead mount (i.e. , on opposing sides along the X-axis).

[0074] This arrangement ensures that the compensation system can react to bending or dynamic disturbances in the printhead mount. This configuration not only compensates for staticdeflection or deformation of the printhead mount but also helps to dampen or absorb dynamic mechanical vibrations that may arise during operation.

[0075] Preferably, the two compensation mechanisms along with their pivoting mechanisms are positioned symmetrically on opposite lateral sides of the printhead mount, forming a side- mounted configuration on the lateral sides of the printhead mount, that is, along the left and right sides when viewed in the direction of media feed or printhead travel.

[0076] Specifically, each compensation mechanism, such as a spring, dashpot, or a combination thereof, can be mounted between a side surface of the printhead mount and a corresponding structural frame positioned laterally adjacent to that side. Each compensation mechanism is operatively connected to a pivot mechanism, such as a pivotable arm or hinge, which is configured to rotate in response to deflection or displacement of the printhead mount.

[0077] The term "outer side surface of the printhead mount" refers to the external lateral surface of the printhead mount, specifically the left and right exterior faces when the printhead is oriented in its operational position. These surfaces are substantially perpendicular to the direction of printhead travel (e.g., in a scanning printer) or the media feed direction (e.g., in a single-pass printer) and extend along the longitudinal axis X of the printhead mount.

[0078] The compensation system of the present invention comprises preferably two pivot mechanisms. Each pivot mechanism is a mechanical system that allows rotational movement around a fixed axis. Each pivot mechanism may comprise a lever or arm that is mounted to pivot about a fixed axis. Further, one end of each pivot mechanism may be connected to the printhead mount, while the other end is coupled to a compensation mechanism. When the printhead mount experiences vertical deflection / deformation or vibrations due to mechanical loading or thermal effects, the printhead mount exerts a force on the attached pivot mechanism, causing them to rotate about their pivot axes. This rotation causes displacement of the compensation mechanism / element (springs, dashpots), which respond with a restoring or damping force.

[0079] These compensation mechanisms apply restoring or damping forces that counteract deflection, deformation, or vibration of the printhead mount.

[0080] The pivot axis may generally be aligned parallel to the print direction or media feed direction, enabling the arms / lever to rotate in response to vertical deflection of the printhead mount and thereby activate associated compensation elements (such as springs and / or dashpots).

[0081] Specifically, the pivot mechanism may comprise one or more rotational joints, flexural pivots, flexure-based mechanisms, bearings, hinge pins, or other hinge-like elements disposedbetween the printhead mount and the side frame. Rotational joints may include bearings or bushings to reduce friction, while flexural pivots may rely on the elastic deformation of compliant members to provide frictionless, backlash-free rotation.

[0082] Specifically, in a single-pass digital printing system, the mechanical stability of the printhead mount is essential, as even slight vertical vibrations or deflections can cause uneven ink deposition, banding, or dot placement errors.

[0083] In the present invention, the digital printing system comprises a plurality of printhead mounts positioned along the axis Y (the direction of substrate movement) . Each printhead mount is designed to minimize the distance between adjacent printheads along the substrate feed direction (Y-axis), ideally limited only by the physical dimensions of the printhead housings themselves. This close spacing (or separation gap) helps maintain precise registration between printheads during printing.

[0084] The printhead spacing is the spacing between printheads mounted on successive printhead mounts along the media feed direction (Y-axis). If the spacing between two consecutive printhead mounts (i.e., along the Y-axis) is too large, even small variations in substrate stretch (Al= (F ■ I) / (A ■ E), where F = tension force, I = distance between two fixed points; A = cross- sectional area of the substrate; E = Young’s modulus of the substrate) can lead to misregistration, where the output of the printhead is misaligned with the previous one.

[0085] To minimize the spacing between successive printhead mounts aligned along the Y-axis (the direction of substrate movement), the present invention eliminates any compensation mechanisms or supporting structures along the length of the printhead mount in the X-axis direction. Specifically, there are no compensation mechanisms or additional supporting structures placed above or along the top of the printhead mount.

[0086] Instead, all compensation elements / mechanisms are mounted externally on the vertical side surfaces of the printhead mount (along the Z-axis), facing outward along the Y-axis.

[0087] This design choice, with no overhead structures on the printhead mount eliminates the need for additional mechanical clearances that would otherwise increase the spacing between printheads mounted on two successive printhead mounts arranged along the media feed direction (Y-axis) or simply would increase the space between successive printhead mounts along the Y-axis, potentially compromising registration accuracy.

[0088] As a result, the printheads can be mounted with minimal gap (distance (I)) between them, limited only by the physical dimensions of the printhead bodies. This configuration not only reduces structural complexity but also helps to minimize substrate stretch-relatedmisregistration by shortening the distance between printheads and maintaining registration accuracy within tight drop-placement tolerances.

[0089] Further, the distance between the first and second printhead mounts is limited only by the physical dimensions of the printheads mounted thereon. The first and second printhead mounts can be spaced apart by a distance, the value of which is determined by the physical width of the print heads and a minimum mechanical clearance (the smallest physical spacing that must be maintained between two components), such that the mounts are positioned in a compact, consecutive arrangement along the Y-axis.

[0090] The spacing between printhead mounts along the media feed direction (Y-axis) is selected so that the misregistration caused by substrate stretch is limited to a predefined error margin defined by the count of drops the substrate is stretched. For example, if printing is performed at 300 dots per inch (dpi), the centre-to-centre dot spacing is approximately 25.4 mm / 300 dpi = 0.0847 mm (84.7 pm). This dot pitch defines the maximum allowable misregistration between printheads caused by substrate elongation. For example, the substrate stretch is allowed to range from 0 up to 1000 drops, 0 up to 100 drops, 0 up to 10 drops, 0 up to 5 drops, or 0 up to 2 drops. In other words, the distance between the printheads in the length direction is specified in such a way that the drops are out of register compared to the previous beam from 0 up to 1000 drops, 0 up to 100 drops, 0 up to 10 drops, 0 up to 5 drops, or 0 up to 2 drops as a result of the substrate stretch.

[0091] Therefore, all compensation mechanisms are positioned on opposite vertical side surfaces of the printhead mount, outside the printhead mount, that is, on both outer sides along the X-axis, and extend vertically along the Z-axis, in order to avoid unnecessary structural complexity above the printhead mount.

[0092] The compensation system of the present invention comprises at least two compensation mechanisms, referred to as a first compensation mechanism and a second compensation mechanism, arranged symmetrically on opposite sides of the printhead mount, specifically on opposite outer vertical side surfaces of the printhead mount (i.e., on opposing sides along the X- axis). Preferably, the two compensation mechanisms are identical in structure and function to ensure symmetric performance and balanced compensation.

[0093] The compensation mechanisms are oriented along the Z-axis and are mechanically coupled between the printhead mount and a surrounding support frame. This configuration enables a reduced spacing I between adjacent printhead mounts.

[0094] In the present invention, the digital printing system pertains to large-scale digital printers, including single-pass and multi-pass inkjet printers, designed for printing decorative images on various printing media. A multi-pass inkjet printer moves the print heads back and forth across the substrate, building up the image in multiple passes. In contrast, a single-pass inkjet printer has fixed print heads, securely attached to a print bar, that cover the entire width of the substrate, as shown in FIG. 1 . The substrate that is the printing media moves under the fixed print heads, which apply ink in one pass.

[0095] A single-pass inkjet printer is particularly well-suited for industrial applications that require large quantities of prints and high throughput. Their printhead mounts, e.g. print bars, can be designed with an increased length that allows for a wider coverage area, which is essential for printing on large-area objects efficiently. The stability of these long printhead mounts (print bars), exceeding 2 m in length, is crucial, as it reduces the risk of misalignment and ink misapplication. Further, the high printing speeds, inherent to single-pass technology, make it ideal for printing on large-area objects, ensuring efficient and rapid production. This technology is especially advantageous in the interior decoration and industrial application industries, where items such as floor, wall or ceiling coverings (including laminates and ceramic tiles), worktops, mouldings, tarpaulins, and similar products need to be decorated with intricate designs.

[0096] While the present invention exemplifies a single pass printing system, it is not limited thereto and can also be integrated into diverse large-scale printing setups, where compensation for deformations, such as any type of deflection(s), is necessary.

[0097] A printhead mount is a structural component in a digital printing system, such as single pass printer, that supports and positions the printhead modules, which comprise the individual print heads. A single-pass printer can have a plurality of printhead mounts to further enhance printing capabilities and throughput. For example, an industrial single-pass inkjet printer might be equipped with four to six printhead mounts each holding multiple print head modules. Each printhead mount ensures the alignment and stability of the print heads, allowing for consistent and accurate ink application across the entire width of the printing media.

[0098] The at least one printhead mount in a single-pass printer i.e. the digital printing system, may be fixed in place in contrast to multi-pass printers where the printhead moves back and forth across the substrate. The printhead mount may have an elongated body with a specific length, which can be longer than 2 meters, or longer than 3 meters, or even longer than 4 meters, that spans the entire width of the substrate, allowing for continuous and high-speed printing.

[0099] Since the printhead mount is part of the system that holds and supports the printheads, it needs to remain stable and accurately positioned during the printing operation. However, with printhead mounts exceeding 2 meters in length, maintaining precise alignment and stability becomes increasingly challenging.

[0100] To ensure stability, the material selection for a long printhead mount with a length greater than 2 m, or greater than 3 m, or even greater than 4 m, can be critical. The chosen material needs to be strong, rigid, lightweight, and ideally have low thermal expansion to minimize the total deflection, including the maximum deflection, and ensure precise positioning of the print heads. Examples of suitable materials are metals such as aluminium and its alloys, which are lightweight and corrosion-resistant; steel and its alloys, known for their high strength and durability; and titanium and its alloys, which offer an excellent strength-to-weight ratio and high corrosion resistance. Alternatively, fibre-reinforced polymeric materials, commonly known as composites, can also be used. Composites, such as carbon fibre-reinforced polymeric composites provide exceptional rigidity and low weight, while glass fibre-reinforced polymeric composites offer good strength and flexibility. Also, natural fibre-reinforced polymeric material is suitable material for the printhead mount.

[0101] The printhead mount, as a component that holds and positions the printhead in a printer, can be a print bar, a beam, a carriage assembly, a stationary mount.

[0102] In an embodiment, the printhead mount is a print bar. The print bar is a rigid bar that spans the width of the substrate and holds multiple printheads.

[0103] Furthermore, the print bar may have various profiles, such as I-beam, rectangular, box (hollow rectangular), T-beam, C-channel, circular (tube), or H-beam or combinations of the above. For reasons of weight reduction, these profiles may be perforated. These profiles ensure the print bar's stability and structural integrity. This component is crucial for maintaining consistent print quality and achieving high throughput in industrial printing applications.

[0104] Further, the print bar may include integrated cooling channels or thermal management systems to prevent overheating.

[0105] In an embodiment, the print bar is an I-beam. This profile resembles the letter 'I' and has a high strength-to-weight ratio.

[0106] In an embodiment, the elongated body of the printhead mount is made of metal is selected from the group consisting of aluminium, aluminium alloy, steel, steel alloy, titanium, or titanium alloy.

[0107] In an embodiment, the elongated body of the printhead mount is made of fibre- reinforced polymeric material is selected from the group consisting of a carbon fibre reinforced polymeric material or glass fibre reinforced polymeric material or natural fibre reinforced polymeric material. Examples of natural fibre-reinforced polymeric materials include wood plastic composites (WPC), natural fibre composites (NFC) using fibres like jute, flax, hemp, sisal, coir, bamboo, or kenaf.

[0108] In an embodiment the print bar is an aluminium print bar with an I-beam profile.

[0109] In an exemplary embodiment, the print bar is a stainless steel print bar with an I-beam profile.

[0110] In an exemplary embodiment, the print bar comprises carbon fibre-reinforced polymeric material with an I-beam profile.

[0111] Referring to the configuration and use of the digital printing system as illustrated in Figs 1 to 10; three orthogonal directions are further defined: a first direction or vertical direction Z (designated as the Z-axis). The Z-axis represents the vertical direction; a second direction or or horizontal direction Y (designated as the Y-axis) is the media feed direction or along the substrate movement; a third direction X (designated as the X-axis) that is orthogonal to the first two directions, it runs along the length of the printhead mount and thus is the longitudinal direction.

[0112] The digital printing system of the present invention comprises at least one printhead module, preferably a plurality of printhead modules. The printhead modules are attached and supported in a suspended manner above the printing area by the printhead mount, preferably the print bar. They can be aligned along the X-axis, which spans the width of the substrate. They can also be mounted at an angle versus the X-axis. The advancement direction of the substrate is along the Y-axis, which is perpendicular to the X-axis.

[0113] Further, each printhead module comprises a print head. The print head is a component of the digital printing system, responsible for transferring ink onto the substrate (such as paper, plastic, metal, glass, or fabric). The print head comprises a plurality of nozzles that eject ink droplets in a precise manner to create text, images, or patterns on the substrate. Unlike traditional printing methods where the print head moves back and forth across the substrate, single-pass printing employs a fixed print head configuration. In such digital printing systems, a plurality of print heads may be used to cover the entire width of the substrate. As the substrate moves beneath the print head(s), it is printed in one continuous pass, significantly increasing print speed and throughput. However, these printheads, as part of the printhead modules add to the weight on the print bar, which can lead to sagging.

[0114] The printhead mount (e.g. a print bar), along with other components, is attached to at least one support structure, which can be a robust frame. This attachment is typically achieved through well-known mechanical means such as bolted connections or welds. The frame is preferably a fixed frame which acts as the fundamental scaffold of the printer, onto which all other parts are mounted. It can be constructed from heavy steel plates or steel sections (hollow rectangular or square bars) or any other material and section that fulfils the needs of a robust frame. The frame is designed to limit vibrations and enhance structural integrity. In an embodiment, the substrate may be movable with respect to the fixed frame.

[0115] Any type of substrate can be used with the digital printing system of the present invention. For example, the substrate can include polymeric materials such as polyethylene terephthalate (PET), polyolefins (PO), or polyvinyl chloride (PVC), as well as paper, fabric, glass, and metal. The substrate receives a pattern printed by the digital printing system.

[0116] The digital printing system of the present invention may comprise a substrate transport system, as shown in FIG. 1 . The substrate transport system may be designed to move the substrate through the printing apparatus in a single, continuous motion. In this system, the substrate is fed from a supply roll or stack and transported along a fixed path beneath a stationary printhead or array of printheads. As the substrate passes through, the printheads apply the ink or printing material in one uninterrupted pass, resulting in high-speed printing. The transport mechanism typically includes precision rollers, belts, or conveyors to ensure smooth and accurate movement of the substrate, maintaining consistent alignment and tension to achieve optimal print quality. In single-pass printing, the substrate is transported in a controlled manner parallel to the print bar by a substrate transport system, such as conveyor belt.

[0117] Furthermore, during printing operations, the long printhead mount may deform due to forces such as the weight of the printhead modules, thermal expansion, operational vibrations and its own weight. The term “long printhead mount” refers to an elongated body that may exceed a length of 2 meters, or can exceed a length of 3 meters, or can exceed a length of 4 meters. The increased length makes the printhead mount more susceptible to these deformations, and vibrations can exacerbate the issue. This problem becomes more pronounced as the length of the printhead mount increases. This deformation, which can manifest as bending or deflection(s), needs to be compensated for to maintain the desired performance and accuracy. Furthermore, the deformation is an elastic deformation, indicating that it is temporary, and the material will revert to its original shape once the applied stress is removed. This deformation of the printhead mount can affect the jetting distance. Jetting distance is thedistance between the nozzle of a print head and the surface of the substrate onto which the ink droplets are being ejected. It is a critical parameter in inkjet printing that affects print quality, accuracy, and the overall performance of the printing process. Bending or sagging of the print bar due to its length causes variations in the jetting distance along the substrate. For example, if the printhead mount (e.g. the print bar) deflects significantly, this jetting distance will vary, causing some nozzles to be closer or further away from the substrate than others. These variations can lead to inconsistencies in droplet placement, resulting in blurred, uneven prints, and overall reduced print quality. Thus, maintaining a consistent jetting distance is crucial for achieving sharp, accurate, and high-quality prints.

[0118] Minimizing the total deflection of the printhead mount, which supports the print heads, electronics, and ink supply components, is essential for achieving sharp and even prints. In the context of a printhead mount, deflection or total deflection describes how much the printhead mount bends or sags when subjected to forces such as the weight of the print heads, electronics, and other components, or vibrations. The printhead mount is initially straight, with a uniform cross-section and a moment of inertia I. This moment of inertia is a critical factor in determining the printhead mount’s resistance to deflecting or bending.

[0119] As the length (L) of the printhead mount increases for industrial applications, bending becomes more pronounced, as shown in Fig. 6. The total deflection of the printhead mount is proportional to length of the printhead mount. This is due to the deflection(s) of a printhead mount supported on both sides under a uniform load being proportional to the cube of the printhead mount’s length (L3). This means that doubling the length of the print bar for example from about 2 meters to more than 4 meters, results in an eightfold increase in deflection (s)(total deflection). Therefore, minimizing the total deflection is particularly challenging but crucial as the printhead mount lengthens.

[0120] A deflection is a type of deformation (the degree to which a part of a long printhead mount is deformed), such as an elastic deformation, that can occur in various forms, encompassing multiple types of displacements. The term “total deflection” in this application, encompasses all types of deflections. For example, the total deflection may comprise maximum deflection (the greatest displacement occurring at the midpoint of the printhead mount under a given load), axial deflection (displacement along the length of the printhead mount under a given load), vertical deflection ( perpendicular to the length of the printhead mount), lateral deflection (transvers displacement perpendicular to the length of the printhead mount position under agiven load). These examples are not limiting, and the total deflection may include other types of displacements as well.

[0121] Here is the equation provided for a simply supported printhead mount i.e a print bar, with a uniformly distributed load, which is applicable for analysing the deflection 5, maximum deflection 5max, slope, shear, and moment of a printhead mount, in particular a print bar, under similar conditions.Deflection:Slope:

[0122] Components of the Equations1 -3 :The equationl (Eq. 1 ) calculates the deflection 6 at any point x along the printhead mount (print bar).5: represents the deflection at a distance x from one end of the printhead mount ; w: is the uniform load per unit length applied to the printhead mount ; x: the distance from one end of the printhead mount to where the deflection is being calculated; L: the total length of the printhead mount ; E: The modulus of elasticity of the printhead mount material; I: the moment of inertia of the printhead mount 's cross-sectional area. The moment of inertia (I) is a geometrical property of a cross-section that measures its resistance to bending.Equation 2 calculates the maximum deflection (5max). For a symmetrically built printhead mount, e.g. print bar, with even loads across the width, the maximum deflection (5max) occurs at the midpoint of the printhead mount (when x = L / 2). Thus, 5 is the deflection at any point x of theprinthead mount, while 5max (when x = L / 2) is the maximum deflection occurring specifically at the midpoint of the printhead mount. The digital printing system of the present invention addresses the total deflection at any point of the printhead mount, including the maximum deflection. The higher the moment of inertia (I), the less the printhead mount will bend. Equation 3 gives the slope (0) of the deflection curve.

[0123] The total deflection of the printhead mount or the print bar affects the jetting distance, as explained above. A larger total deflection means a greater deviation from the intended jetting distance, which can compromise print quality, as shown in Table 2. This is because precise alignment of the print heads is crucial for maintaining consistent print quality, and any deflection can lead to inaccuracies in the print output. If the total deflection is equal to or greater than the jetting distance, it becomes challenging to print on the substrate.

[0124] Further, the print heads typically move at high speeds, generating significant vibrations and mechanical stresses, which further contribute to potential bending. In particular, these vibrations can affect the printhead mount to flex or bend slightly by introducing dynamic forces that can amplify deflection and bending. These oscillations can create resonance within the printhead mount leading to periodic displacement that exacerbates the initial deflection or total deflection.

[0125] The natural frequency at which the printhead mount, such as print bar, would vibrate is given by the following equation:

[0126]

[0127] where E is the modulus of elasticity, I is the moment of inertia, L is the length, and q is the load (equivalent to w). In this equation, L appears in the denominator raised to the power of 4, meaning that as L increases, the frequency quickly drops to low Hertz, (Hz), making the structure more prone to vibrations.

[0128] Thus, another aim of the present invention is to reduce the bending moments imparted to the printhead mount as a result of vibrations.

[0129] Therefore, the term "total deflection" encompasses any of the deflections described by the provided equations, including static deflection, vertical deflection, maximum deflection, as well as other types of deflections that may occur under different loading conditions or constraints or due to vibrations and dynamic forces.

[0130] The inventors have found that by selecting the materials and designing the printhead mount with a higher moment of inertia (I), they can effectively control and minimize the total deflection. This ensures the print bar maintains a consistent jetting distance, which is crucial for high-quality, precise printing.

[0131] Further, the ratio between maximum deflection and the jetting distance can be between 0.002 and 0.9, for example the ratio can be between 0.002 and 0.5, between 0.002 and 0.6, or between 0.002 and 0.4, or between 0.002 and 0.3, or between 0.002 and 0.2, or between 0.002 and 0.1 , or between 0.002 and 0.09, or between 0.002 and 0.08, or between 0.002 and 0.07, or between 0.002 and 0.06, or between 0.002 and 0.05, or between 0.002 and 0.04, or between 0.002 and 0,02 , or between 0.002 and 0.01 , or between 0.002 and 0.009. This ratio is optimal for jetting distance between 0.1 mm and 5 mm. Further examples of this ratio are presented in Table 3.

[0132] In an embodiment, the ratio between maximum deflection and the jetting distance can be between 0.002 and 0.9, where the jetting distance is between 0.1 mm and 5 mm.

[0133] In an embodiment, the ratio between maximum deflection and the jetting distance can be between 0.002 and 0.1 , where the jetting distance is between 0.1 mm and 2 mm.

[0134] In an embodiment, the jetting distance is between 0.1 mmand2mm where the maximum deflection is between 0.01 and 0.5 mm.

[0135] In an embodiment, the load applied on the printhead mount can be between 20 N / m and 2000 N / m, wherein the load includes the weight of the printhead mount, and the weight of all components attached to the printhead mount, such as the printheads modules. For example, the load can be in the range of from 20 N / m to 1500 N / m, or 20 N / m to 1000 N / m, or 20 N / m to 900 N / m, or 25 N / m to 850 N / m, or 25 N / m to 700 N / m, or 25 N / m to 650 N / m, or 25 N / m to 500 N / m, or 25 N / m to 400 N / m, or 25 N / m to 300 N / m , or 25 N / m to 200 N / m, or 25 N / m to 150 N / m, or 25 N / m to 100 N / m, or 50 N / m to 100 N / m.

[0136] In an embodiment, the printhead mount or print bar has a length greater than 4 meters and is configured to ensure that the jetting distance is between 0.1 and 5 mm and maximum deflection in the range of from 0.001 mm to 1 mm.

[0137] In an embodiment, the printhead mount of the digital printing system with a length greater than 2 meters is designed to accommodate a uniform load per unit length in the range of 50 N / m to 900 N / m, ensuring minimal total deflection and consistent print quality. For example, the uniform load per unit length may be in the range of from 50 N / m to 850 N / m, or 150 N / m to 800 N / m.

[0138] In an embodiment, the digital printing system may have a printhead mount length rangingfrom 2 meterto 15 meters, for example in the range between 2 m and 14 m, or 2 m and 13 m, or,2mand 12m, or2mand 11 m,or2mand 10m, or2mand9 m, or2mand8m,or2mand 7m,or2mand6m, or 3mand6m,or4mand6 m.

[0139] The jetting distance can be maintained within the ratio of from 0.1 mm to 5 mm, more preferably between 0.1 mm and 2 mm, therefore the maximum deflection is preferably between 0.01 mm and 0.1 mm, even more preferably between 0.01 mm and 0.075 mm. By selecting an appropriate material (with a known E) of the printhead mount and designing it with the required I, the total deflection can be minimized. By calculating the appropriate I for a given printhead mount length L and material E and ensuring the total deflection (also the maximum deflection) remains within the acceptable range, the digital printing system can achieve the desired performance and accuracy. Table 4 shows the ratio between maximum deflection and the length of the printhead mount.

[0140] In an embodiment, the jetting distance is in the range of from 0.1 mm to 5 mm, preferably from 0.1 to 4 mm, more preferably from 0.1 mm to 3 mm, or even more preferably in the range of from 0.1 mm to 2 mm.

[0141] In an embodiment the jetting distance is in the range of from 0.1 mm to 2 mm. For example, the jetting distance may be in the range of from 0.1 mm to 1 .5 mm, or from 0.1 mm to 1 mm, or from 0.1 mm to 0.8 mm, or from 0.1 to 0.5 mm, or from 0.1 mm to 0.4 mm, or 0.1 mm to 0.3 mm.

[0142] In an embodiment, the printhead mount is configured to maintain a maximum deflection within the range of from 0.01 mm to 1 mm for a jetting distance in the range between 0.1 m and 5 mm.Thus, the present invention provides a digital printing system that ensures that the total deflection being the sum of one or more types of deflections, is less than 90 % of the jetting distance , preferably less than 50 % of the jetting distance , more preferably less than 20 % of the jetting distance, or less than 15 % of the jetting distance, preferably less than 10 % of the jetting distance, more preferably less than 5 % of the jetting distance, or even more preferably less than 3 % of the jetting distance, or less than 2 % of the jetting distance, or less than 1 % of the jetting distance throughout the printing operation, thereby maintaining a consistent jetting distance and ensuring high-quality print output. The term “total deflection” herein refers to any type of deflection along the printhead mount, including for example the maximum deflection. Thus, the maximum deflection is less than 90 % of the jetting distance , preferably less than 50 % of the jetting distance , more preferably less than 20 % of the jetting distance, or less than 15 % of the jetting distance, preferably less than 10 % of the jetting distance, more preferably less than 5 % of the jetting distance, or even more preferably less than 3 % of the jetting distance, or less than 2 % of the jetting distance, or less than 1 % of the jetting distance throughout the printing operation, thereby maintaining a consistent jetting distance and ensuring high-quality print output.

[0143] In an embodiment, the maximum deflection of the printhead mount (e.g. print bar) is between about 0.01 to 0.5 mm under varying uniform loads per unit length.

[0144] In an embodiment, the printhead mount has a length of approximately 2 meters and is configured to ensure that the maximum deflection is between 0.1 mm to 0.3 mm under varying uniform loads per unit length.

[0145] Based on this calculation, the appropriate printhead mount design can be determined by selection for example an appropriate profile and size for the printhead mount. The maximumdeflection of the printhead mount is directly related to maintaining a consistent jetting distance. The inventors have found that keeping the maximum deflection in the range of from 1 % to 20 % of the jetting distance, more preferably from 1 % to 5 %, ensures that nozzles of the printhead remain at an optimal and uniform distance from the substrate, thereby guaranteeing high-quality printing results.

[0146] In addition, to address the problem of bending in long printhead mounts, the digital printing system of the present invention includes a compensation system designed to counteract both (total) deflection and vibrations of the printhead mount during printing operations on a substrate. This is in addition to selecting a specific material for the printhead mount and ensuring that the moment of inertia (I) meets the required value to minimize the total deflection, which is the maximum deflection.

[0147] Each printhead mount of the digital printing system comprises at least one, compensation system, where the compensation system is configured to counteract the total deflection of the printhead mount, including both static deflection (e.g., due to structural sag or misalignment) and dynamic deflection (e.g., due to vibration or transient forces), along one or more of the X, Y, and Z-axes. The compensation system may mitigate displacement along one or more of the X, Y, and Z axes by applying restoring and / or damping forces, thereby maintaining accurate printhead positioning during operation.

[0148] In an embodiment, the compensation system is configured to counteract the total deflection in both the vertical (Z-axis) and horizontal (Y-axis) directions, as illustrated in Figures 6 through 9. Further, the compensation system can comprise two or more compensation mechanisms, preferably dynamic compensation mechanisms, arranged on opposite sides of the printhead mount, specifically on opposite outer vertical side surfaces of the printhead mount (i.e., on opposing sides along the X-axis). Each compensation mechanism is designed to actively monitor and adjust the position or behaviour of components in real-time to counteract any deviations caused by external forces, deformations, or operational conditions thereby maintaining a consistent jetting distance during printing operations on a substrate. For example, when the printhead mount bends due to external forces, a detector / sensor, such as strain gauges, accelerometers, laser displacement sensors, or dial indicators, magnetic sensors, can be used to monitor the bending, vibrations, and temperature changes.

[0149] Further, the compensation system may use a camera-based optical system to assess bending compensation by employing, for example, the Triangle Similarity Method. The camerabased system measures the bending of the printhead mount by analysing images of knownmarkers, using the apparent size to calculate distances, and thereby detecting any deviations or deformations.

[0150] The compensation system of the present invention may comprise at least one, preferably two or more compensation mechanisms configured to oppose and counteract the forces causing deformation, specifically elastic deformation. The elastic deformation may include one or more types of deflections that define a total deflection, where the total deflection includes any type of deflection, also encompassing the maximum deflection. Preferably, each compensation system can be configured to counteract the deflection, referred to as a total deflection, of the printhead mount by providing opposing forces in at least one direction. For example, each compensation system can counteract the total deflection in both the vertical (z-axis) and horizontal (y-axis) directions using one or more compensation mechanisms.

[0151] Further the compensation system may comprise at least one, preferably two pivot mechanisms, one or more sensors to dynamically monitor the total deflection, and especially the maximum deflection, of the printhead mount, actuators for precise adjustments, and a feedback mechanism to ensure precise control.

[0152] Each compensation mechanism is operatively connected to the printhead mount and supported by the frames, wherein the at least one compensation mechanism is a counterbalancing mechanism. This compensation mechanism(s) is designed to actively counteract forces and stresses, including those caused by the weight and motion of the printhead mount during the printing process, thereby reducing bending and maintaining structural integrity.

[0153] By mitigating bending and preserving structural integrity, it dynamically adjusts to varying operational conditions such as changes in load, speed, or printhead mount movement direction. This ensures consistent performance and extends the lifespan of machine components. The system employs a combination of elements, including adjustable weights, tension springs, hydraulic or pneumatic dampers, and spindles.

[0154] The compensation mechanism(s) can be selected from hydraulic means, spindles, springs, or counterweights, pretension bars, temperature-actuated bars, dashpots or combinations thereof.

[0155] The compensating mechanism(s) that can be used to prevent deformation, such as the total deflection, that can include for example maximum deflection, of printhead mounts can be an active compensation mechanism or passive compensation mechanisms.

[0156] The active compensation mechanisms actively oppose and counteract the forces causing deformation. They typically involve actuators that apply forces or moments to the printhead mount to maintain its desired position or shape. Examples of active compensation mechanisms may include hydraulic actuators, pneumatic actuators, electrical actuators, temperature-driven actuators.

[0157] Hydraulic actuators utilize pressurized fluid to generate forces and movements. They are well-suited for applications where high forces are required. Pneumatic actuators operate by using compressed air to generate forces and movements. They are lighter and more compact than hydraulic actuators, but they generally offer lower force output. Electrical actuators use electric motors to generate forces and movements. They provide precise control and are relatively efficient, but they may be heavier than hydraulic or pneumatic actuators.

[0158] Passive compensation mechanisms rely on the inherent properties of materials or structures to counteract deformation. They typically involve springs, dampers, or viscoelastic materials that absorb or dissipate energy from the deforming printhead mount. Examples include springs, weights, dampers, spindles. Springs are a type of elastic elements that provide a restoring force proportional to the amount of deformation. They are simple and effective for compensating small deflections, but also any type of deflection. Examples of such springs include helical springs, which are coiled and commonly used for compression and tension, and leaf springs, which are flat and used in applications requiring the absorption of large loads and shocks.

[0159] In an embodiment, the digital printing system of the present invention comprises one or more first and second compensation mechanisms, where first and second compensation mechanisms each comprise one or more first and one or more second hydraulic cylinders and / or one or more first and one or more second elastic elements. For example, the elastic elements can be springs or spindles.

[0160] In some embodiments, the compensation system of the digital printing system is a dual compensation system comprising two compensation mechanisms, each implemented as a dashpot mounted on opposite lateral sides of the printhead mount. In such embodiments, the compensation system therefore comprises two dashpots arranged to provide symmetrical damping, particularly for the purpose of reducing vibrations affecting the printhead mount during operation. Each dashpot is operatively coupled to a printhead mounts via pivoting mechanisms, for example compensation arms, and are positioned to respond to vertical deflection or vibration of the mounts during operation. The dashpots are configured to resist vibrational movement bydissipating kinetic energy through viscous damping. The dashpots, working in conjunction on both sides of a single printhead mount, can apply controlled resistance against deformation or oscillation of the printhead mount, thereby stabilizing its position during dynamic operation. By damping both high-frequency and low-frequency vertical vibrations along the Z-axis, the dashpots contribute to improved printhead stability and consistent nozzle-to-substrate distance.

[0161] In a further embodiment, each lateral side of the printhead mount is coupled to a spring and a dashpot in parallel, forming a spring-damper pair.

[0162] In an embodiment, the first and second compensation mechanism is a dashpot or a combination of one or more dashpots and one or more springs. For example, dashpots may consist of a piston or plunger moving within a cylinder filled with a viscous fluid, such as oil or silicone. The springs can handle gradual movements and provide restoring force (elastic force) when compressed or stretched, while dashpots act to dampen any sudden movements or vibrations that could otherwise affect print alignment or quality.

[0163] For example, commercially suitable dashpots can be selected from, but are not limited to, hydraulic shock absorbers, rotary dampers, or linear viscous dampers, depending on the specific mounting configuration and the direction of the forces to be damped.

[0164] In an embodiment, the digital printing system comprises first and second compensation mechanisms, where the first and second compensation mechanisms are pretensioned bars.

[0165] In an embodiment, the first and second compensation mechanisms are combination of pretension bars and hydraulic cylinders, or a combination of pretension bars and dashpots.

[0166] In an embodiment, first and second compensation mechanisms are temperature- actuated bars or a combination of temperature-actuated bars and elastic elements, hydraulic cylinders, dashpots. Temperature -actuated bars are mechanical components designed to respond to changes in temperature and comprising materials with a high coefficient of thermal expansion, such as certain metals or alloys. For example, the temperature-actuated bars can be installed along the length of the printhead mount.

[0167] Spindles, as a type of elastic element, serve as an example of an active compensation mechanism. The spindle is a cylindrical rotating component, is integrated into the structure of the digital printing system and connected to the printhead mount. It's designed to apply corrective forces along the length of the printhead mount. As the printhead mount experiences load, it tends to bend or sag. The spindle mechanism activates to counteract this bending. It can do this through either manual adjustment or an automated system. The spindle rotates to apply an opposing force to the areas experiencing the greatest load, effectively distributing the stress andreducing bending. The material of the spindle can be selected from a high strength steel alloy, titanium alloy, composite materials, nickel-based alloys. Damping is the process of reducing vibrational or oscillatory movements in a physical system, typically through the use of dampers that dissipate energy. Dampers work by absorbing energy from the deforming printhead mount, thereby decreasing the rate at which it deforms. This reduction in deformation rate helps stabilize the system and minimizes unwanted oscillations. They are often used in conjunction with springs to provide a combination of stiffness and damping. Viscoelastic materials exhibit both elastic and viscous behaviour, providing a combination of stiffness and damping. They can be used in various forms, such as damping pads or strips.

[0168] The damping should be such that the system is critically damped which means adjusting the damping coefficient so the printhead mount returns to its original state: if we express the damping force as R = -b.v, with b = a constant, then b should be chosen so that b / 2.m = w0„ where m is the mass of the system and w0is its natural frequency). Alternatively, the system can be overdamped, where b / 2.m > w0. In a real-life situation, multiple vibration frequencies may occur. In that case, the system can be tuned in such a way that at least 20%, 30%, preferably up to 70%, or even up to 99%, or even up to 99.99 % of the vibrations can be damped.

[0169] In an embodiment, the digital printing system comprises at least one compensation mechanism that includes: a hinge pin with a bearing configured to serve as a pivot mechanism, providing a fixed axis for the printhead mount, around which the printhead mount pivots, a first and a second elastic element (e.g. at least one spring or at least one spindle) each connected to the printhead mount and anchored to the frame, designed to counteract various types of deflections (total deflection) by providing a restoring force, thereby maintaining the printhead mount within specified deflection limits. For example, the maximum deflection to jetting distance ratio can be maintained within the range between 0.002 and 0.5, or even between 0.002 and 0.1 .

[0170] In some embodiments, there is provided a digital printing system for printing on a substrate comprising: at least one print bar with a length greater than 2 m, at least one printhead module supported by the print bar, one or more support structures configured to support the print bar, and at least one compensation system configured to prevent total deflection of the at least one print bar, wherein the at least one compensation system comprises one or more compensation mechanism, known as first and second compensation mechanisms, at least one, preferably two pivot mechanisms, such as hinge pin, a control system and means for measuring displacement, wherein the total deflection is less than 20 % of the jetting distance, preferablyless than 10 % of the jetting distance. The maximum deflection can also be less than 20 % of the jetting distance, preferably less than 10 % of the jetting distance. Further, the first and second compensation mechanism can be selected from one or more springs, spindles, hydraulic cylinders, dash pots, pretensioned bars, temperature- actuated bars or combination thereof.

[0171] In some embodiments, each of the first and second compensation mechanisms comprises one or more dashpots configured to provide damping compensation for mechanical disturbances, such as displacement, deformation, and vibration, affecting the printhead mount. With reference to FIG. 2, the digital printing system 100 comprises a print bar, i.e. a printhead mount, 1 10 spanning a width of the substrate (not shown) along the substrate width direction X and support structures 130 extending in the vertical direction Z. The at least one printhead module 140 is mounted on the print bar 1 10. In this figure the print bar 1 10 comprises an elongate body spanning the width of the substrate in the substrate width direction X. The printhead module(s) 140 may be connected to the print bar 1 10. In some examples a plurality of printhead modules 140 may be mounted on the print bar to cover the width of the substrate. Each print head module 140 comprises a printhead. Fig. 2 further illustrates the double compensation system comprising two compensation mechanism (120,150) on each side of the print bar 1 10, and two pivot mechanisms120. Each hinge pin (pivot mechanism) 120 is connected to the support structure 130 and the print bar 1 10. Further, Fig. 2 illustrates two elastic elements 150, that are springs.

[0172] In an embodiment, this digital printing system 100 uses a combination of at least two pivot mechanisms, at least two springs, and sensors 160 to dynamically monitor and correct the total deflection in the print bar 1 10, i.e., a printhead mount. Each hinge pin(s) 120 translates the print bar's bending into a motion that the springs can counteract, while the sensors provide realtime feedback to a control system 170, which adjusts the compensation mechanism to maintain stability and print quality. The hinge pin with a bearing ensures smooth motion and effective force translation, and the frame provides a stable anchor point for the springs. The springs essentially work to 'pull back' against the bending, thereby reducing or neutralizing the total deflection (bending) of the printhead mount.

[0173] In an embodiment, the hydraulic means for the compensation mechanism is a hydraulic cylinder equipped with sensors and control systems in conjunction with hinge pins acting as pivot mechanisms. These hydraulic cylinders are in communication with the printhead mount (i.e. a print bar) and are connected to a hydraulic control unit. The sensors, such as a dial indicator, continuously monitor the deflection(s) of the printhead mount. When a deflection is detected, thecontrol unit adjusts the position of the piston within the cylinders. The hydraulic cylinders apply a compensating force through the hinge pins, which serve as pivot mechanisms, thereby counteracting the deformation. The dynamic feedback system ensures that any deflection is quickly corrected, maintaining consistent print quality and minimizing vibrations.

[0174] With reference FIG. 3, the digital printing system 200 comprises a print bar 210, that is a printhead mount, spanning the width (L) of the substrate (not shown) along the substrate width direction X and support structures 230 extending in the vertical direction Z. At least one printhead module 240 is mounted on the print bar 210. In this figure, the print bar 210 comprises an elongated body spanning the width of the substrate in the substrate width direction X. The printhead module 240 may be connected to the print bar body 210. In some examples, a plurality of printhead modules 240 may be mounted on the print bar to cover the width of the substrate. Each printhead module 240 comprises a printhead. Fig. 3 further illustrates the double compensation system comprising two compensation mechanism (220, 250) on each side of the print bar 210. Each hinge pin (pivot mechanism) 220 is connected to the support structure 230 and the print bar 210. Further, FIG. 3 illustrates hydraulic cylinders 250. The hydraulic cylinders 250 can dynamically adjust their piston’s position to counteract any bending or sagging, ensuring that the print bar remains straight and the printheads maintain a consistent distance from the printing surface.

[0175] In some cases, a hybrid approach combining active and passive compensation mechanisms may be optimal.

[0176] FIG. 4 is another embodiment of the present invention. With reference to FIG. 4, the digital printing system 300 comprises a print bar 310, i.e. , printhead mount, spanning the width (L) of the substrate (not shown) along the substrate width direction X and support structures 330 extending in the vertical direction Z. At least one printhead module 340 is mounted on the print bar 310. In this figure, the print bar 310 comprises an elongated body spanning the width of the substrate in the substrate width direction X. The printhead module 340 may be connected to the print bar body 310. In some examples, a plurality of printhead modules 340 may be mounted on the print bar to cover the width of the substrate. Each printhead module 340 comprises a printhead. Fig. 4 further illustrates the double compensation system comprising two compensation mechanism (320,350) on each side of the print bar 310. In Fig. 4, two pivot mechanisms, 320 i.e. hinge pins, are provided, with one positioned at each end of the print bar 310 to enable controlled rotational movement relative to the support structure.

[0177] Each hinge pin (pivot mechanism) 320 is connected to the support structure 330 and the print bar 310. Further, FIG. 4 illustrates compensation mechanisms 350, which are a combination of springs and hydraulic cylinders.

[0178] FIG. 5 is another embodiment of the present invention. With reference to FIG. 5, the digital printing system 400 comprises a print bar 410, i.e. a printhead mount, spanning the width (L) of the substrate (not shown) along the substrate width direction X and support structures 430 extending in the vertical direction Z. At least one printhead module 440 is mounted on the print bar 410. In this figure, the print bar 410 comprises an elongated body spanning the width of the substrate in the substrate width direction X. The printhead module 440 may be connected to the print bar body 410. In some examples, a plurality of printhead modules 440 may be mounted on the print bar to cover the width (X-axis) of the substrate. Each printhead module 440 comprises a printhead. Fig.5 further illustrates the double compensation system comprising two compensation mechanism 450 on each side of the print bar 410, and two pivot mechanisms, 420 i.e. hinge pins. Each hinge pin (pivot mechanism) 420 is connected to the support structure 430 and the print bar 410. Further, FIG. 5 illustrates an adjustment mechanism 450, which is a spindle.

[0179] In this configuration, the spindle (450) provides precise adjustment and support for the print bar (410). The spindle can be manually or automatically adjusted to fine-tune the position of the print bar, ensuring it remains stable and aligned. This adjustment mechanism allows for the correction of any deflection (total deflection) or misalignment that might occur due to the weight of the printhead modules (440) or other operational factors. By maintaining a consistent printhead-to-substrate (jetting) distance, the spindle helps ensure high print quality across the entire width of the substrate.

[0180] Fig. 6 provides a front view of the digital printing system, illustrating the issue of total deflection in the printhead mount 1 10 in the Z-direction (Z-axis). Fig. 6 highlights the mechanical stress and the resulting total deflection of the printhead mount under operational conditions. The depiction shows areas susceptible to bending.

[0181] Further, with reference to FIG. 6, that is an embodiment of the invention, the digital printing system 100 comprises a printhead mount 1 10 referred herein as a print bar. The system 100 further comprises frames 130 supporting the print bar, pivot mechanisms 120, 180, with two mounted on each side of the print bar. Further, the digital printing system 100 comprises primary helical springs 150, optionally secondary helical springs 190 (not shown), mounted on each side of the print bar and printhead modules 140. The helical springs 150 are aligned in the Z direction(vertical) to counteract forces acting vertically, such as the weight of components and downward forces due to oscillation. The helical springs 190 (not shown) are aligned in the Y direction to counteract forces that may act horizontally, potentially from lateral movements or vibrations. Furthermore, the helical springs 190 represent one option for compensation mechanism in the Y- direction; other alternatives can include hydraulic cylinders or various types of compensation mechanisms. The same options apply to compensation in the Z direction.

[0182] Fig. 7 provides a front view of the digital printing system, illustrating the correction (Z- axis) of the total deflection of the print bar shown in Fig. 6. With reference to Fig. 7, the digital printing system 100 comprises a printhead mount 1 10 referred herein as a print bar. The system 100 further comprises frames 130 supporting the print bar, primary pivot mechanisms 120, primary helical springs 150, mounted on each side of the print bar, optionally secondary helical springs 190 (not shown) and also mounted on each side of the print bar, printhead modules 140. This setup corrects deflection(s) of the print bar in the Z-direction, ensuring accurate printhead positioning and improved print quality.

[0183] Fig. 8 provides top-down view of the digital printing system, illustrating the issue of total deflection in the Y-direction of the printhead mount 1 10. The digital printing system comprises a printhead mount 1 10 referred herein as a print bar. The system further comprises frames 130 supporting the print bar, secondary pivot mechanisms 180, secondary helical springs 190.

[0184] Fig. 9 provides top-down view of the digital printing system, illustrating the correction of the deflection(s) (Y-axis) of the print bar shown in Fig. 8. The digital printing system comprises a printhead mount 1 10 referred herein as a print bar. The system comprises frames 130 supporting the print bar, secondary pivot mechanisms 180, secondary helical springs 190, mounted on each side of the print bar. This setup corrects the deflection (s) of the print bar in the Y-direction, ensuring accurate printhead positioning and improved print quality.

[0185] Fig. 10. illustrating an embodiment of the compensation system comprising first compensation mechanisms connected to the frame 130 and having a plurality of elastic elements, such as helical springs (150,190) and a plurality of hinge pins. The helical springs (150,190) are used to counteract this bending (deflection, total deflection) by providing opposing forces in both the vertical (Z-axis) and horizontal (Y-axis) directions. The primary helical springs 150 are aligned in the Z direction (vertical) to counteract forces acting vertically, such as the weight of components and downward forces due to oscillation. The secondary helical springs 190 are aligned in the Y direction to counteract forces that may act horizontally, potentially from lateral movements or vibrations. Although only the first compensation mechanisms are shownhere, the opposite side frame 130 of the digital printing system mirrors this structure, incorporating the same components and functionality as the first compensation mechanisms. In particular, the opposite side comprises a second compensation mechanism, structurally and functionally identical to the first, which includes corresponding elastic elements (e.g., helical springs) and hinge pins mounted in the same configuration as the first compensation mechanisms. Together, the first compensation mechanisms and the second compensation mechanisms form a symmetrical dual compensation system that supports the print bar and enables controlled deflection compensation on both sides.

[0186] Example 1

[0187] In an exemplary embodiment, the printhead mount is a print bar made of aluminium and has a length (L) of the print bar of 4 meters (L=4 m) and is preferably an I-beam. Given that the maximum allowable deflection 5max=0.1 mm=0.1 x 10-3 m; Modulus of elasticity for aluminium (E) is 70 GPa, E~70 GPa=70*109Pa and given the uniform load per unit length (w) is 100 N / m, then for an aluminium print bar that is 4 meters long, to ensure that the maximum deflection does not exceed 0.1 mm, the area moment of inertia (I) should be at least 9.52x10-9 m4. For 6max=0.2 mm, the area moment of inertia (I) is 4.76 x 10-9 m4. For 6max=0.3 mm, the area moment of inertia (I) is 3.17 x 10-9 m4.

[0188] Table 1 shows a non-limiting example of incoming substrate used during printing.

[0189] Table 1Table 2 illustrates the ratio of bending (maximum deflection) to jetting distance.Table 3 shows the maximum deflection of the print bar, also referred to as print beam, for various print bar (print beam) lengths. Table 3 shows the ratio of the maximum deflection to the print bar length. As the print bar length increases, the maximum deflection values increase for each deflection level. Thus, the longer the print bar, the more it bends or deflects under a given load. Table 4 shows a non-limiting embodiment of an aluminium print bar. It shows the deflection of the print bar vs. its moment of Inertia (I) and versus its length. With reference to Table 4 the printhead mount is a print bar made of aluminium. The length of the print bar can range from 0.5 m to 7 m. The uniform load per unit length (w) is 750 N / m. The load calculated includes the weight of the print bar and the printhead modules, totalling 750 N / m.Table 5 shows a non-limiting embodiment of a steel print bar. It shows the deflection of the print bar vs. its moment of Inertia (I) and versus its length. The length of the print bar can range from 0.5 m to 7 m. The load calculated includes the weight of the print bar and the printhead modules, totalling 1000 N / m. The modulus of elasticity (E modulus) of steel typically ranges between 190 GPa and 210 GPa.Table 6 shows a non-limiting embodiment of a carbon fibre-reinforced polymeric (CFRP) print bar. It shows the deflection of the print bar vs. its moment of Inertia (I) and versus its length. The length of the print bar can range from 0.5 m to 7 m. The load calculated includes the weight of the print bar (100 N / m) and the printhead modules (500 N / m), totalling 600 N / m . Further, modulus of elasticity of CFRP can range from 70 GPa to 230 GPa.Table 4 shows a non-limiting embodiment of an aluminium print bar (printhead mount) and illustrates the deflection of the print bar vs. its moment of Inertia (I) and versus its length). The moment of inertia determines the printhead mount's resistance to bending.Table 5 shows a non-limiting embodiment of a steel print bar, i.e. a printhead mount, illustrating the deflection of the print bar vs. its moment of Inertia (I) and versus its length Table 5Table 6

Claims

CLAIMS1 . A digital printing system for printing on a substrate comprising: at least one printhead mount, at least one printhead module supported by the printhead mount, one or more support structures configured to support the printhead mount, at least one compensation system configured to prevent deformation and / or vibration of the at least one printhead mount, wherein the compensation system comprises at least two compensation mechanisms, arranged symmetrically on opposite outer sides of the printhead mount.

2. The digital printing system according to claim 1 , wherein the compensation mechanisms are configured to operate in coordination to counteract mechanical disturbances affecting the printhead mount, including displacement, deformation, or vibration.

3. The digital printing system according to claim 1 , wherein each compensation mechanism is positioned outside an outer vertical side surface of the printhead mount, extending along Z-axis and facing outward along X-axis.

4. The digital printing system according to any one of the preceding claims, wherein a plurality of printhead mounts are arranged sequentially along a substrate feed direction (Y axis), and wherein a distance between the each pair of consecutive printhead mounts along the Y-axis is determined by the physical width of the printheads mounted on the first and the second printhead mounts and a defined separation gap, and wherein no components of the compensation system are positioned between or above the first and second printhead mounts.

5. The digital printing system according to any one of the preceding claims, wherein each printhead module comprises a printhead adapted to carry out printing and having a plurality of nozzles, wherein a distance between the nozzles and the substrate is defined as a jetting distance.

6. The digital printing system according to any one of the preceding claims, wherein the at least one printhead mount has an elongated body with a length greater than 2 meters spanning the width of the substrate.

7. The digital printing system according to any one of the preceding claims, wherein the elongated body comprises metal, or fibre-reinforced polymeric material.

8. The digital printing system according to claim 7, wherein the metal is selected from the group consisting of aluminium, aluminium alloy, steel, steel alloy, titanium, or titanium alloy.

9. The digital printing system according to claim 7, wherein the fibre-reinforced polymeric material is selected from the group consisting of a carbon fibre-reinforced polymeric material, glass fibre-reinforced polymeric material, or natural fibre-reinforced polymeric material.

10. The digital printing system according to any of the preceding claims, wherein the at least one compensation system comprises one or more first and one or more second compensation mechanisms.1 1 . The digital printing system according to any of the preceding claims, wherein the at least one compensation system further comprises at least two pivot mechanisms.

12. The digital printing system according to any of the preceding claims, wherein the printhead mount is coupled to two pivot mechanism positioned symmetrically on opposite sides of the printhead mount, wherein each pivot mechanism is configured as a pivot axis about which a component of the compensation system is configured to rotate in response to deformation or vibration of the printhead mount.

13. The digital printing system according to any one of claims 11 or 12, wherein each pivot mechanism is a hinge pin,14. The digital printing system according to claim 13, wherein each hinge pin is configured to translate the deformation of the printhead mount into rotational movement around the hinge pin itself.

15. The digital printing system according to any of the preceding claims, wherein the compensation system is configured to prevent elastic deformation of the printhead mount, wherein the elastic deformation includes one or more types of deflections that define a total deflection, and / or to dampen dynamic mechanical disturbances.

16. The digital printing system according to any one of the preceding claims, wherein the compensation system is configured to counteract the total deflection along one or more of the X, Y, and Z axes, including a maximum deflection.

17. The digital printing system according to any of the preceding claims, wherein the compensation system is configured to counteract the total deflection along both the vertical (Z- axis) and horizontal (Y-axis) directions.

18. The digital printing system according to any of claims 16 or 17, wherein the total deflection being the sum of one or more types of deflections, is less than 90 % of the jetting distance, preferably less than 50 % of the jetting distance, more preferably less than 20 % of the jetting distance, even more preferably less than 10 % of the jetting distance.

19. The digital printing system according to any of claimsl O to 18, wherein the one or more first and the one or more second compensation mechanisms are one or more first and one or more second elastic elements, damping elements, or viscoelastic elements, each configured to counteract at least one force exerted by the at least one printhead on the printhead mount.

20. The digital printing system according to any one of claims 10 to 19, wherein the one or more first and the one or more second elastic elements are a springs and / or spindles.21 . The digital printing system according to claim 19, wherein the one or more first and one or more second elastic elements are pretensioned bars.

22. The digital printing system according to any one of claims 10 to 21 , wherein the one or more first and one or more second compensation mechanisms each comprise one or more first and one or more second hydraulic cylinders and / or one or more first and one or more second elastic elements.

23. The digital printing system according to any one of claims 10 to 22, wherein the one or more first and one or more second compensation mechanisms are temperature-actuated bars.

24. The digital printing system according to any of the preceding claims, wherein the one or more first and one or more second compensation mechanisms comprise dashpots.

25. The digital printing system according to any of claims 2 to24, wherein the jetting distance is in the range of from 0.1 mm to 5 mm.

26. The digital printing system according to any of the preceding claims, wherein ratio between the maximum deflection and the jetting distance is between 0.002 and 0.9.

27. The digital printing system, according to any of the preceding claims, wherein the printhead mount is a print bar.

28. The digital printing system of any of the preceding claims, wherein the compensation system further comprises a control system configured to automatically adjust the at least one compensation mechanism.

29. The digital printing system of any of the preceding claims, wherein the digital printing system is a single-pass inkjet printer or multi-pass inkjet printer.

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