Controlling movement of flexible intermediate transfer member

Abstract

A system (11) includes (a) an actuator (23, 25, 27) configured to tilt a roller (99, 77, 76) as an intermediate transfer member (ITM) (44) of a printing system (11) moves thereon; and a controller (54, 20) configured to (i) identify a deformation of the ITM (44), and (ii) control the actuators (23, 25, 27) to tilt the rollers (99, 77, 76) to reduce the deformation when moving the ITM (44).

Description

Field of the Invention

[0001] The present invention generally relates to digital printing and, more particularly, to methods and systems for controlling the movement of a flexible intermediate transfer member during a printing process. Background of the Invention

[0002] Some printing systems include one or more intermediate transfer members that are typically moved to receive an image and transfer the image to a target substrate. Various techniques for moving such intermediate transfer members have been disclosed. Summary of the Invention

[0003] Embodiments of the invention described herein provide a system that includes an actuator and a controller. The actuator is configured to tilt a roller as an intermediate transfer member (ITM) of a printing system moves thereon, and the controller is configured to: (i) identify a deformation of the ITM, and (ii) control the actuator to tilt the roller to reduce the deformation when moving the ITM.

[0004] In some embodiments, the ITM moves along a continuous path in a first direction, and the controller is configured to reduce the deformation by: (i) identifying a first moving speed of the ITM in a second direction different from the first direction, and (ii) controlling the actuator to tilt the roller to move the ITM at a second moving speed less than the first moving speed while the ITM is moving in the first direction.

[0005] In other embodiments, the controller is configured to receive a signal indicating the first moving speed and control the actuator in response to receiving the signal. In still other embodiments, the system includes: (i) a first edge sensor positioned at a first segment of the continuous path and configured to generate a first signal indicating the first moving speed at the first segment, and (ii) a second edge sensor positioned at a second segment of the continuous path different from the first segment and configured to generate a second signal indicating the first moving speed at the second segment.

[0006] In some embodiments, in response to receiving the first signal and the second signal, the controller is configured to identify a first deformation in the first segment and a second deformation in the second segment.

[0007] In other embodiments, the system includes a first actuator configured to tilt a first roller and a second actuator configured to tilt a second roller, and in response to identifying the first deformation and the second deformation, the controller is configured to control at least one of the first actuator and the second actuator to tilt the first roller and the second roller, respectively.

[0008] In still other embodiments, the controller is configured to: (i) control a first actuator to tilt a first roller at a first tilt angle, and (ii) control a second actuator to tilt a second roller at a second tilt angle different from the first tilt angle.

[0009] In some embodiments, the controller is configured to control the first actuator and the second actuator to apply the first tilt and the second tilt simultaneously. In other embodiments, the ITM is configured to receive ink droplets to form an ink image thereon and to transfer the ink image to a target substrate. In still other embodiments, the controller is configured to: (i) maintain a look-up table (LUT) that includes one or more known deformations caused by one or more operations implemented in the printing system, and (ii) control the actuators to tilt the rollers according to the LUT to reduce the one or more known deformations.

[0010] In some embodiments, one or more known deformations include a first known deformation in a first section of the ITM and a second known deformation in a second section of the ITM, and include a first actuator configured to tilt a first roller of the printing system and a second actuator configured to tilt a second roller of the printing system, and in response to identifying the first known deformation and the second known deformation, the controller is configured to control at least one of the first actuator and the second actuator to tilt the first roller and the second roller, respectively.

[0011] In other embodiments, the controller is configured to: (i) control a first actuator to tilt a first roller at a first tilt angle, and (ii) control a second actuator to tilt a second roller at a second tilt angle different from the first tilt angle. In still other embodiments, the controller is configured to control the first actuator and the second actuator to apply the first tilt and the second tilt simultaneously.

[0012] In some embodiments, the controller is configured to: (i) maintain a neural network (NN) configured to identify one or more known deformations caused by one or more operations implemented in the printing system, and (ii) in response to a given operation in the printing system, control the actuators to tilt the rollers according to the output of the NN to reduce the one or more known deformations.

[0013] In other embodiments, the controller is configured to receive one or more signals respectively indicating one or more additional deformations, and the controller is configured to apply the NN to identify whether at least one of the one or more known deformations includes at least one of the one or more additional deformations. In still other embodiments, the controller is configured to apply the NN to control the actuators in response to receiving the signal.

[0014] In some embodiments, the printing system includes at least a first roller and a second roller, and the controller is configured to control an actuator to tilt the first roller such that at least the first roller and the second roller are not parallel to each other. In other embodiments, deformation of the ITM causes deflection of the roller, where the roller is moved by a drive and includes an encoder configured to generate a deflection signal indicative of the deflection angle of the roller, and the controller is configured to identify the deformation of the ITM based on the deflection signal.

[0015] In still other embodiments, the system includes: (i) a chassis and at least a first printing bar and a second printing bar, the printing bars being coupled to the chassis and configured to apply droplets of a first color and a second color to the ITM to respectively produce a first pattern and a second pattern of an image on the ITM; and (ii) at least a given edge sensor coupled to the chassis and configured to produce (a) a first edge signal indicative of a first position of the chassis and (b) a second edge signal indicative of a second position of an edge of the ITM moving relative to at least the first printing bar and the second printing bar.

[0016] In some embodiments, deformation in the chassis causes a color-to-color (C2C) registration error between the first pattern and the second pattern of the image, and based on the first edge signal and the second edge signal, the controller is configured to: (i) identify the deformation of the chassis, (ii) estimate the C2C registration error, and (iii) control the actuator to tilt the roller to reduce the C2C registration error by compensating for the deformation of the chassis while (a) moving the ITM and (b) the first printing bar and the second printing bar apply droplets of the first color and the second color.

[0017] In some embodiments, the controller is configured to control at least the first printing bar and the second printing bar to adjust at least one of a first time and a second time at which droplets of the first color and the second color are applied, respectively, to reduce the C2C registration error in the image.

[0018] In other embodiments, the ITM has a plurality of markers formed along at least one edge of the ITM at a predefined distance from each other and includes one or more sensors configured to generate a plurality of signals respectively indicative of the plurality of positions of the plurality of markers, and the controller is configured to control at least one of the following based on the plurality of signals: (i) a first moving speed, and (ii) an actuator.

[0019] In still other embodiments, at least one of the markers includes a plurality of trapezoids, and the controller is configured to estimate at least one of the following based on a plurality of signals respectively indicating the plurality of positions of the plurality of trapezoids: (i) the moving speed in a first direction, and (ii) a first moving speed.

[0020] In some embodiments, the plurality of trapezoids include a plurality of right trapezoids, the plurality of right trapezoids respectively having: (i) a plurality of orthogonal sides that are orthogonal to the first direction; and (ii) a plurality of diagonal sides that extend at a predefined angle with respect to the first direction, and the controller is configured to estimate the moving speed at least in the first direction based on a plurality of signals respectively indicating the respective plurality of positions of the orthogonal sides.

[0021] In other embodiments, the plurality of markers include: (i) a first marker having a first orthogonal side and a first diagonal side, and (ii) a second marker having a second orthogonal side and a second diagonal side, and the controller is configured to receive a given signal indicating the orthogonal side and the diagonal side, and based on the signal, identify the deformation of the ITM by estimating the following: (a) a first distance between the first orthogonal side and the first diagonal side, and (b) a second distance between the second orthogonal side and the second diagonal side.

[0022] In still other embodiments, in response to the movement of the ITM in a second direction, the controller is configured to: (i) identify the difference between the first distance and the second distance, and (ii) estimate the magnitude of the movement of the ITM in the second direction based on the following: (a) the estimated difference between the first distance and the second distance, and (b) a predefined angle.

[0023] In some embodiments, the plurality of trapezoids include a plurality of isosceles trapezoids, the plurality of isosceles trapezoids respectively having: (i) a plurality of third diagonal sides that extend at a first angle with respect to the first direction; and (ii) a plurality of fourth diagonal sides that extend at a second angle with respect to the first direction, the controller is configured to receive a third signal and a fourth signal respectively indicating the third position and the fourth position of the third diagonal side and the fourth diagonal side, the plurality of isosceles trapezoids include a first isosceles trapezoid and a second isosceles trapezoid located at a given distance, and based on the third signal and the fourth signal, the controller is configured to identify the deformation of the ITM by estimating the following: (a) a third distance between the third diagonal side and the fourth diagonal side of the first isosceles trapezoid, and (b) a fourth distance between the third diagonal side and the fourth diagonal side of the second isosceles trapezoid.

[0024] In other embodiments, the controller is configured to estimate the magnitude of movement of the ITM in a second direction based on: (a) the difference between the estimated third and fourth distances, and (b) the first and second angles.

[0025] In some embodiments, at least one of the markers includes one or more polygons having pairs of sides orthogonal to a first direction, and the controller is configured to estimate the speed of movement at least in the first direction based on a given signal that respectively indicates the given positions of one or more of the pairs of sides.

[0026] In other embodiments, the ITM has a first axis and a second axis orthogonal to the first axis, the marker includes a third marker formed by one or more first sides along the first axis, and a fourth marker formed by one or more second sides along the second axis, and the controller is configured to: (i) identify at least one of: (a) a third deformation of the ITM based on the third marker, (b) a fourth deformation of the ITM based on the fourth marker, and (c) a fifth deformation of the ITM based on the third and fourth markers; and (ii) control the actuator to tilt the roller to reduce at least one of the third, fourth, and fifth deformations when moving the ITM.

[0027] In some embodiments, based on at least one of a plurality of signals, the controller is configured to control the operation of at least one station or component of the system. In other embodiments, the at least one station or component is selected from the list consisting of: (a) an image forming station configured to apply ink droplets to the ITM and produce an image on the ITM, (b) an impression station configured to transfer the image to a target substrate, (c) at least one roller configured to move the ITM, (d) one or more drying components configured to at least partially dry the ink droplets on the ITM, and (e) an ITM processing station.

[0028] In some embodiments, the impression station includes a rotatable impression cylinder and a rotatable pressure cylinder configured to transfer an image to a target substrate, and based on at least one of a plurality of signals, the controller is configured to control at least one operation selected from the list consisting of: (a) the timing of engagement and disengagement between the impression cylinder and the pressure cylinder, (b) the motion profile of at least one of the impression cylinder and the pressure cylinder, and (c) the magnitude of the gap between the disengaged impression cylinder and the pressure cylinder.

[0029] According to one embodiment of the present invention, a method is further provided, the method including identifying a deformation of an intermediate transfer member (ITM) moving on a roller of a printing system. An actuator is controlled to tilt the roller to reduce the deformation when moving the ITM.

[0030] The present invention will be more fully understood from the following detailed description of embodiments thereof in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic side view of a digital printing system according to an embodiment of the present invention;

[0032] Figure 2A is a schematic top view of an embodiment of the present invention showing an undesired movement of a blanket of a digital printing system during a printing process and a sensor configured to detect a position of an edge of the blanket;

[0033] Figure 2B is a schematic top view of an embodiment of the present invention showing compensation for an undesired movement of a blanket during a printing process;

[0034] Figure 3 is a schematic illustration of an embodiment of the present invention showing control of movement of a blanket in a Y-axis;

[0035] Figure 4 is a schematic side view of a blanket according to an embodiment of the present invention and a graph for showing a method for differentiating between a blanket cutting error and an undesired movement of the blanket;

[0036] Figure 5 is a flowchart of a method for reducing deformation of a blanket undesirably moving along a Y-axis during a printing process according to an embodiment of the present invention;

[0037] Figure 6A is a schematic top view of an embodiment of the present invention showing alignment between movement of a blanket and Figure 1 pattern printing of a printing bar of a system;

[0038] Figure 6B is a schematic top view of an embodiment of the present invention showing detection of an undesired deformation in a blanket of a digital printing system during a printing process; and

[0039] Figure 7 is a schematic top view of an embodiment of the present invention showing detection of a deformation in a side wall of a chassis of a digital printing system, the deformation causing a color-to-color (C2C) registration error during a printing process. DETAILED DESCRIPTION

[0040] Overview

[0041] Some printing systems have a movable intermediate member configured to receive an image and transfer the image to a target substrate. In some cases, the intermediate member is flexible and may deform when moved, resulting in distortion in the printed image and reducing the printing output of the printing system.

[0042] In principle, the edges of the flexible intermediate member can be coupled to a transport subsystem configured to control the movement of the intermediate member. An example of a transport subsystem is a zipper, which is configured between the transport subsystem and the intermediate member. However, such a coupling mechanism (e.g., a zipper) can introduce non-uniform flexibility in the flexible member and, thus, can result in distortion in the printed image and various malfunctions in the operation of the printing system.

[0043] Embodiments of the present invention described below provide an improved technique for controlling the movement of a flexible intermediate member (ITM) to reduce or prevent distortion when moving the ITM to print an image.

[0044] In some embodiments, a digital printing system (also referred to herein as a system for simplicity) includes an image forming system configured to apply droplets of one or more printing fluids to an ITM (also referred to herein as a blanket) to create an image thereon. The system includes an impression station configured to transfer the image from the blanket to a target substrate, such as a sheet or a continuous web, for example, by alternately engaging and disengaging between the blanket and the target substrate.

[0045] In some embodiments, the blanket is formed as an endless loop (e.g., using a seam between the ends of the blanket), and the system includes a plurality of rollers for moving and guiding the blanket along an endless continuous path such as shown below. Figure 1 and Figure 3 Some rollers are motorized and controlled by a controller of the system for moving and guiding the blanket, while other rollers are not motorized and are mainly used for guiding the moving blanket.

[0046] In some embodiments, the system includes one or more actuators configured to tilt one or more corresponding rollers of the system when the blanket moves on the system.

[0047] In some embodiments, the controller of the system is configured to identify and reduce the deflection of the blanket. The deflection identification and reduction can be implemented in a proactive mode (i.e., before it occurs), or in a reactive mode (i.e., after it occurs), or in a combination of both modes, as will be described herein.

[0048] In some embodiments, the system includes one or more sensors positioned at one or more corresponding sections of the system. When the blanket moves in a first direction, e.g., along the X-axis of the system to perform printing, the one or more sensors are configured to generate one or more corresponding signals that indicate the position of one or both edges of the blanket in a second direction different from the first direction. In this example, the second direction is parallel to the Y-axis of the system, and the Y-axis is orthogonal to the X-axis. Embodiments related to the sensors and the corresponding signals will be described in more detail, for example, in the following Figure 2A , Figure 3 and Figure 4 .

[0049] In some embodiments, in the reactive mode, the controller is configured to receive signals from the sensors, and based on the signals, the controller is configured to calculate or estimate the speed of movement of the blanket along the y-axis in the corresponding section of the system. For example, in a first section where printing bars arranged along the X-axis are used to apply droplets to the blanket, the movement of the blanket along the Y-axis can cause color-to-color (C2C) registration errors, which will be described in detail in the following Figure 1 and Figure 2A . Similarly, in a second section positioned in the system before an image is transferred to a target substrate, the movement of the blanket along the Y-axis can cause registration errors in the position of the image on the target substrate, also referred to herein as image-to-substrate (I2S) registration errors, which will be described in detail in the following Figure 1 and Figure 2A .

[0050] In some embodiments, the controller is configured to maintain one or more thresholds indicative of the allowed speed of movement of the blanket along the Y-axis. It should be noted that since the specifications for C2C registration errors are more stringent than those for I2S registration errors, the corresponding thresholds for the maximum allowed speeds can be different from each other.

[0051] In some embodiments, in passive mode, when the estimated moving speed of the blanket in a given section is identified as being greater than a corresponding threshold, the controller is configured to control one or more actuators to tilt one or more corresponding rollers at a selected angle to reduce the moving speed of the blanket along the Y-axis when moving the blanket. It should be noted that roller tilting reduces the deformation of the blanket in a given section of the system and improves the quality of the printed image. Embodiments related to passive mode will be described in more detail, for example, in Figure 2A 、 Figure 3 and Figure 4 below.

[0052] In some embodiments, the controller is configured to maintain a look-up table (LUT) that includes one or more known deformations caused, respectively, by one or more operations implemented in the system. For example, changing the blade in a blanket handling (e.g., cleaning) station, as described in detail in Figure 3 below, can change the force applied to the moving blanket and can result in a known movement (and thus deformation) of the blanket along the Y-axis. Embodiments related to the LUT will be described in more detail, for example, in Figure 3 below.

[0053] In some embodiments, in active mode, the controller is configured to control one or more actuators to tilt the corresponding rollers before starting a printing job in order to actively prevent deformation of the blanket that can be caused by uncontrolled movement of the blanket along the Y-axis, as described above.

[0054] In other embodiments, instead of or in addition to the LUT, the controller is further configured to maintain a neural network (NN) that is trained to identify one or more deformations in the blanket caused by uncontrolled movement of the blanket along the Y-axis. Embodiments related to the NN will be described in more detail, for example, in Figure 3 below.

[0055] The disclosed techniques improve the quality of the images printed in the system and increase the productivity of such printing systems. Embodiments related to additional improvements, such as but not limited to reducing the occurrence of memory effects, are described in the detailed description below.

[0056] System Description

[0057] Figure 1FIG. 0 is a schematic side view of a digital printing system 10 according to an embodiment of the present invention. In some embodiments, the system 10 includes a rolling flexible blanket 44 that circulates through an image forming station 60, a drying station 64, an impression station 84, and a blanket handling station 52. In the context of the present invention and in the claims, the terms "blanket" and "intermediate transfer member (ITM)" are used interchangeably and refer to a flexible member that includes one or more layers serving as an intermediate member, the flexible member being formed as an endless loop that is configured to receive, for example, an ink image from the image forming station 60 and transfer the ink image to a target substrate, as will be described in detail below.

[0058] In one mode of operation, the image forming station 60 is configured to form a mirror image ink image of a digital image 42 on the upper run of the surface of the blanket 44, also referred to herein as an "ink image" (not shown) or simply as an "image" for brevity. Subsequently, the ink image is transferred to a target substrate (e.g., paper, folding carton, multi-layer polymer, or any suitable flexible packaging in the form of a sheet or continuous web) located below the lower run of the blanket 44.

[0059] In the context of the present invention, the term "run" refers to the length or segment of the blanket 44 between any two given rollers that guide the blanket 44.

[0060] In some embodiments, during installation, the blanket 44 can be adhered edge-to-edge using a seam section (also referred to herein as seam 45) to form a continuous blanket loop (also referred to herein as a closed loop). Examples of methods and systems for seam installation are described in detail in U.S. Patent Application Publication 2020 / 0171813, the disclosure of which is incorporated herein by reference.

[0061] In some embodiments, the image forming station 60 generally includes a plurality of printing bars 62, each printing bar 62 being mounted on a frame (not shown) positioned at a fixed height above the surface of the upper run of the blanket 44. In some embodiments, each printing bar 62 includes a string of printheads that are approximately as wide as the printing area on the blanket 44 and includes individually controllable print nozzles that are configured to eject ink and other classes of printing fluids onto the blanket 44, as will be described in detail below.

[0062] In some embodiments, the image forming station 60 may include any suitable number of printing bars 62, which are also referred to herein as bars 62 for the sake of brevity. Each bar 62 may contain a printing fluid, such as aqueous inks of different colors. The inks typically have visible colors, such as, but not limited to, cyan, magenta, red, green, blue, yellow, black, and white. In Figure 1 the example of Figure 1 , the image forming station 60 includes seven printing bars 62, but may include, for example, four printing bars 62 having any selected colors, such as cyan (C), magenta (M), yellow (Y), and black (K).

[0063] In some embodiments, the printhead is configured to eject ink droplets of different colors onto the surface of the blanket 44 to form an ink image (not shown) on the surface of the blanket 44. In this example, the blanket 44 moves along the X axis of the XYZ coordinate system of the system 10, and the ink droplets are directed by the printhead, generally parallel to the Z axis of the coordinate system.

[0064] In some embodiments, the different printing bars 62 are spaced apart from each other along a moving axis, which is also referred to herein as (i) the moving direction 94 of the blanket 44 or (ii) the printing direction. In this example, the moving direction of the blanket 44 is parallel to the X axis, and each printing bar 62 extends along the Y axis of the XYZ coordinates of the system 10. In this configuration, the exact spacing between the bars 62 along the X axis and the synchronization between the ink droplets guiding each bar 62 and the moving blanket 44 are crucial for achieving the correct placement of the image pattern.

[0065] In the context of the present disclosure and in the claims, the terms "color-to-color pattern placement", "pattern placement accuracy", "color-to-color registration", "C2C registration", "color-to-color position difference", "bar-to-bar registration", and "color registration" may be used interchangeably and refer to the placement accuracy of two or more colors relative to each other.

[0066] In some embodiments, the system 10 includes a heater 66, such as a hot gas or air blower and / or an infrared-based heater having a gas or air blower for flowing gas or air at any suitable temperature. The heater 66 is positioned between the printing bars 62 and is configured to partially dry the ink droplets deposited on the surface of the blanket 44. This air flow between the printing bars can help, for example, (i) reduce condensation at the surface of the printhead and / or dispose of splashes (e.g., residues or small droplets distributed around the main ink droplets), and / or (ii) prevent clogging of the orifices of the inkjet nozzles of the printhead, and / or (iii) prevent the ink droplets of different colors on the blanket 44 from undesirably merging with each other.

[0067] In some embodiments, system 10 includes a drying station 64 configured to direct infrared radiation and cold air (or another gas) and / or blow hot air (or another gas) onto the surface of the blanket 44. In some embodiments, drying station 64 may include an infrared-based irradiation assembly (not shown) and / or an air blower 68 or any other suitable drying device.

[0068] In some embodiments, in drying station 64, the ink image formed on blanket 44 is exposed to radiation and / or hot air to more thoroughly dry the ink, thereby evaporating most or all of the liquid carrier and leaving only a layer of resin and colorant heated to the point of becoming a tacky ink film.

[0069] In some embodiments, system 10 includes a blanket module 70 (also referred to herein as an ITM module) that includes a rolling flexible ITM, such as blanket 44. In some embodiments, blanket module 70 includes one or more rollers 78, at least one of which includes a motion encoder (not shown) configured to record the position of blanket 44 in order to control the position of sections of blanket 44 relative to the corresponding printing bars 62. In some embodiments, one or more motion encoders may be integrated with additional rollers and other moving components of system 10.

[0070] In some embodiments, the foregoing motion encoder generally includes at least one rotary encoder configured to generate a rotation-based position signal indicative of the angular displacement of the corresponding roller. It should be noted that in the context of the present invention and in the claims, the terms "indicative of" and "indication" may be used interchangeably.

[0071] Additionally or alternatively, blanket 44 may include an integrated encoder (not shown) for controlling the operation of the various modules of system 10. One implementation of an integrated motion encoder is described in detail, for example, in PCT International Publication WO 2020 / 003088, the disclosure of which is incorporated herein by reference.

[0072] In some embodiments, blanket 44 may include a fabric (not shown) and any suitable type of additional layer. Detailed embodiments related to the structure of stacked layers of any suitable blanket, such as blanket 44, are provided in, for example, PCT International Publication WO 2017 / 208144 and PCT Patent Application PCT / IB2019 / 055288, the disclosures of which are incorporated herein in their entirety by reference.

[0073] In some embodiments, the fabric of the blanket 44 includes two or more sets of fibers (not shown) that are interlaced with each other. In this example, the two sets of fibers are substantially orthogonal to each other, and the fibers of one set are parallel to each other and arranged parallel to the direction of movement 94. Additionally, the fabric of the blanket 44 has an opacity that varies according to a periodic pattern of the fibers.

[0074] In some embodiments, the fabric of the blanket 44 can include any suitable number of fibers, for example, between 20,000 and 30,000 fibers. In a set of fibers arranged parallel to the direction of movement 94, the distance between each fiber and / or adjacent fibers can be used as a position reference along the movement axis of the blanket 44.

[0075] In some embodiments, the processor 20 of the system 10 (described below) can use the position of one or more fibers of the blanket 44 to control the position and movement parameters of the blanket 44. For example, detailed embodiments related to controlling the movement of the blanket 44 are provided in PCT International Publication WO 2021 / 044303, the disclosure of which is incorporated herein by reference.

[0076] In some embodiments, the blanket 44 is guided over the rollers 78, idler 76, and other rollers described herein and over a powered tensioning roller, which is also referred to herein as a dancer assembly 74. The dancer assembly 74 is configured to control the slack length of the blanket 44 and its movement is schematically indicated by the double-headed arrow in Figure 1 In addition, any stretching of the blanket 44 due to aging will not affect the ink image placement performance of the system 10 and will only require taking up more slack by tensioning the dancer assembly 74.

[0077] In some embodiments, both the idler 76 and the dancer assembly 74 can be motorized, and the idler 76 is described in more detail below in Figure 3 In addition, the configuration and operation of the roller 78 are described in more detail, for example, in U.S. Patent Application Publication 2017 / 0008272 and the PCT International Publication WO 2013 / 132424 mentioned above, the disclosures of which are incorporated herein in their entirety by reference.

[0078] In some embodiments, the system 10 includes a blanket tension drive roller (BTD) 99 and a blanket control drive roller (BCD) 77, which are powered by respective first and second motors (generally electric motors (not shown)) and are configured to rotate about their own first and second axes, respectively. For example, the BTD 99 is coupled to the rotor of the electric motor, and the stator of the electric motor is coupled to the chassis of the system 10. The same arrangement applies to the BCD 77.

[0079] In some embodiments, each of idler 76, BCD 77, and BTD 99 is configured to rotate about a respective axis (also referred to herein as a rotational axis). The axis of rotation of each of idler 76, BCD 77, and BTD 99 may include a rotatable roller as shown in FIG. 2 below. In some embodiments, at least one and typically each rotatable roller of idler 76, BCD 77, and BTD 99 has a fixed first end configured to act as a pivot, and a second end configured to move about the pivot at one or more controlled angles, as will be described in detail in FIG. 2 below.

[0080] In some embodiments, system 10 includes one or more tension sensors disposed at one or more locations along blanket 44 (shown below in Figure 2A , Figure 2B , Figure 3 and Figure 4 ). Each edge sensor is configured to generate a signal indicative of the position of an edge of blanket 44 (as shown below in Figure 2A , Figure 2B , Figure 3 and Figure 4 ) along the Y-axis, where the Y-axis is orthogonal to the direction of movement 94 of blanket 44.

[0081] In some embodiments, system 10 may include one or more tension sensors (not shown) disposed at one or more locations along blanket 44. The tension sensors may be integrated within blanket 44 or may include sensors external to blanket 44 that use any other suitable technique to obtain a signal indicative of the mechanical tension applied to blanket 44. In some embodiments, processor 20 and additional controllers of system 10 are configured to receive the signals generated by the tension sensors in order to monitor the tension applied to blanket 44 and control the operation of floating roller assembly 74 and other components (such as but not limited to idler 76, BCD 77, and BTD 99).

[0082] In some embodiments, at impression station 84, blanket 44 passes between impression cylinder 82 and pressure cylinder 90, which is configured to carry a compressible blanket. In some embodiments, a motion encoder is integrated with at least one of impression cylinder 82 and pressure cylinder 90.

[0083] In some embodiments, system 10 includes a console 12 configured to control a plurality of modules of system 10, such as blanket module 70, image forming station 60 located above blanket module 70, and substrate transport module 80 located below blanket module 70 and including one or more impression stations, as will be described below.

[0084] In some embodiments, the console 12 includes a processor 20 (commonly a general-purpose processor) having suitable front-end and interface circuitry for docking with the controller of the floating roller assembly 74 and the controller 54 via the cable 57 and for receiving signals from the controllers. Additionally or alternatively, the console 12 may include any suitable type of application-specific integrated circuit (ASIC) and / or digital signal processor (DSP) and / or any other suitable class of processing unit configured to perform any category of processing on the data processed in the system 10.

[0085] In some embodiments, the controller 54, schematically shown as a single device, may include one or more electronic modules mounted on the system 10 at predefined locations. At least one of the electronic modules of the controller 54 may include electronic devices such as control circuitry or a processor (not shown) configured to control the various modules and stations of the system 10. In some embodiments, the processor 20 and the control circuitry may be programmed with software to implement the functions used by the printing system and to store the software's data in the memory 22. For example, the software may be downloaded electronically to the processor 20 and the control circuitry via a network, or the software may be provided on a non-transitory tangible medium such as an optical memory medium, a magnetic memory medium, or an electronic memory medium.

[0086] In some embodiments, the console 12 includes a display 34 configured to display data and images received from the processor 20 or inputs inserted by a user (not shown) using the input device 40. In some embodiments, the console 12 may have any other suitable configuration, for example, alternative configurations of the console 12 and the display 34 are described in detail in U.S. Patent 9,229,664, the disclosure of which is incorporated herein by reference.

[0087] In some embodiments, the processor 20 is configured to display a digital image 42 on the display 34, the digital image including one or more segments (not shown) of the image 42 and / or various types of test patterns that may be stored in the memory 22.

[0088] In some embodiments, the blanket treatment station 52 (also referred to herein as the cooling station) is configured to treat the blanket 44 by, for example, cooling the blanket and / or applying a treatment fluid to the outer surface of the blanket 44 and / or cleaning the outer surface of the blanket 44. At the blanket treatment station 52, the temperature of the blanket 44 can be reduced to a desired temperature level before the blanket 44 enters the image forming station 60. The treatment can be implemented by passing the blanket 44 over one or more rollers or blades, which are configured to apply cooling and / or cleaning and / or treatment fluid to the outer surface of the blanket.

[0089] In some embodiments, the blanket treatment station 52 can also include one or more bars (not shown) positioned adjacent to the printing bar 62 such that the treatment fluid can be applied to the blanket 44 by spraying additionally or alternatively.

[0090] In some embodiments, the processor 20 is configured to receive, for example, a signal indicating the surface temperature of the blanket 44 from a temperature sensor (not shown) to monitor the temperature of the blanket 44 and control the operation of the blanket treatment station 52. Examples of such treatment stations are described in, for example, PCT International Publications WO 2013 / 132424 and WO 2017 / 208152, the disclosures of which are incorporated herein by reference in their entirety.

[0091] In Figure 1 an example, the station 52 is mounted between the impression station 84 and the image forming station 60. However, the station 52 can be mounted at any other or additional one or more suitable positions adjacent to the blanket 44 between the impression station 84 and the image forming station 60. As described above, the station 52 can be mounted additionally or alternatively on a bar adjacent to the image forming station 60.

[0092] In Figure 1 an example, the impression cylinder 82 and the pressure cylinder 90 imprint an ink image onto a target flexible substrate (such as a single sheet 50), and the target flexible substrate is conveyed from the input stack 86 through the impression station 84 to the output stack 88 by the substrate conveying module 80. In this example, a rotary encoder (not shown) is integrated with the impression cylinder 82.

[0093] In some embodiments, the lower run segment of the blanket 44 selectively interacts with the impression cylinder 82 at the impression station 84 to imprint an image pattern onto the target flexible substrate compressed between the blanket 44 and the impression cylinder 82 by the pressure action of the pressure cylinder 90. In Figure 1 the case of a simplex printing press (i.e., printing on one side of the sheet 50) as shown, only one impression station 84 is required.

[0094] In other embodiments, module 80 may include two or more impression cylinders (not shown) to allow duplex printing at one or more locations. The configuration of the two impression cylinders also enables single-sided printing at twice the speed of printing double-sided printed matter. In addition, a large number of mixed single-sided printed matter and double-sided printed matter can also be printed. In alternative embodiments, different configurations of module 80 can be used for printing on continuous web substrates. For example, detailed descriptions and various configurations of duplex printing systems and systems for printing on continuous web substrates are provided in U.S. Patents 9,914,316 and 9,186,884, PCT International Publication WO 2013 / 132424, U.S. Patent Application Publication 2015 / 0054865, and U.S. Provisional Application 62 / 596,926, and the disclosures of the publications and applications are all incorporated herein by reference.

[0095] As briefly described above, a sheet 50 or continuous web substrate (not shown) is carried by the module 80 from an input stack 86 and passes through a nip (not shown) located between the impression cylinder 82 and the pressure cylinder 90. Within the nip, the surface of the blanket 44 carrying the ink image is firmly pressed against the sheet 50 (or another suitable substrate), such as by a compressible blanket of the pressure cylinder 90, so that the ink image is impressed onto the surface of the sheet 50 and cleanly separated from the surface of the blanket 44. The sheet 50 is then conveyed to the output stack 88.

[0096] exist Figure 1 In the example of , roller 78 is positioned at the upper run of blanket 44 and is configured to keep blanket 44 taut while traveling adjacent to image forming station 60. In addition, it is particularly important to control the speed of blanket 44 under image forming station 60 in order to obtain accurate ejection and deposition of ink droplets to form an image on the surface of blanket 44 by image forming station 60.

[0097] In some embodiments, the impression cylinder 82 periodically engages and disengages the blanket 44 to transfer the ink image from the moving blanket 44 to the target substrate passing between the blanket 44 and the impression cylinder 82. In some embodiments, the system 10 is configured to apply a torque to the blanket 44 using the aforementioned roller and dancer roller assembly to keep the upper run taut and substantially isolate the upper run of the blanket 44 from mechanical vibrations occurring in the lower run.

[0098] In some embodiments, the system 10 includes an image quality control station 55 (also referred to herein as an automatic quality management (AQM) system) that functions as a closed-loop inspection system integrated into the system 10. In some embodiments, such as Figure 1As shown, the image quality control station 55 can be positioned adjacent to the impression cylinder 82 and / or at any other suitable location in the system 10.

[0099] In some embodiments, the image quality control station 55 includes a camera (not shown) configured to acquire one or more digital images of the aforementioned ink image printed on the sheet 50. In some embodiments, the camera can include any suitable image sensor (such as a contact image sensor (CIS) or a complementary metal oxide semiconductor (CMOS) image sensor) and a scanner that includes a slit having a width of about one meter or any other suitable width.

[0100] In the context of the present disclosure and in the claims, the term "about" or "substantially" for any numerical value or range indicates a suitable dimensional tolerance that allows a portion or set of components to function to achieve its intended purpose as described herein.

[0101] In some embodiments, the station 55 can include a spectrophotometer (not shown) configured to monitor the quality of the ink printed on the sheet 50.

[0102] In some embodiments, the digital images acquired by the station 55 are transmitted to a processor (such as processor 20 or any other processor of the station 55) configured to evaluate the quality of the corresponding printed image. Based on the evaluation and the signals received from the controller 54, the processor 20 is configured to control the operation of the modules and stations of the system 10. In the context of the present invention and in the claims, the term "processor" refers to any processing unit (such as processor 20 or any other processor or controller connected to or integrated with the station 55) configured to process the signals received from the camera and / or spectrophotometer of the station 55. It should be noted that the signal processing operations, control-related instructions, and other computational operations described herein can be implemented by a single processor or shared among multiple processors of one or more corresponding computers.

[0103] In some embodiments, the station 55 is configured to inspect the quality of the printed image and test pattern to monitor various attributes, such as but not limited to full-image registration with the sheet 50 (also referred to herein as image-to-substrate registration), color-to-color (C2C) registration, printed geometry, image uniformity, color profile and linearity, and the functionality of the printing nozzles. In some embodiments, the processor 20 is configured to automatically detect geometric deformations or other errors in one or more of the aforementioned attributes.

[0104] In some embodiments, the processor 20 is configured to analyze the detected deformations in order to apply corrective actions to a faulty module, and / or feed instructions to another module or station of the system 10 in order to compensate for the detected deformations.

[0105] In some embodiments, the system 10 may print test marks (not shown) or other suitable features, for example, at the bevel or edge of the sheet 50. By acquiring an image of the test marks, the station 55 is configured to measure various types of deformations, such as C2C registration, image-to-substrate registration, different widths between colors (referred to herein as "bar-to-bar width difference" or "color-to-color width difference"), various types of local deformations, and front-to-back registration errors (in duplex printing). In some embodiments, the processor 20 is configured to: (i) pick the sheet 50 having deformations higher than a first set of predefined thresholds to, for example, a reject tray (not shown); (ii) initiate a corrective action for the sheet 50 having deformations higher than a lower second set of predefined thresholds; and (iii) output the sheet 50 having minor deformations, for example, lower than the second set of thresholds, to the output stack 88.

[0106] In some embodiments, the processor 20 is configured to detect deviations in the profile and linearity of the printed colors based on signals received from the spectrophotometer of the station 55.

[0107] In some embodiments, the processor of the station 55 is configured to decide whether to stop the operation of the system 10, for example, when the density of the deformation is higher than a specified threshold. The processor of the station 55 is also configured to initiate a corrective action in one or more of the modules and stations of the system 10, as described above. In some embodiments, the corrective action may be implemented immediately (while the system 10 continues the printing process), or implemented offline by stopping the printing operation and resolving the problems in the corresponding modules and / or stations of the system 10. In other embodiments, any other processor or controller of the system 10 (e.g., the processor 20 or the controller 54) is configured to initiate a corrective action or stop the operation of the system 10 when the density of the deformation is higher than a specified threshold.

[0108] Additionally or alternatively, the processor 20 is configured to receive, for example from the station 55, signals indicating additional types of deformations and problems during the printing process of the system 10. Based on these signals, the processor 20 is configured to automatically estimate the pattern placement accuracy level and additional types of deformations and / or defects not mentioned above. In other embodiments, any other suitable method for inspecting the pattern printed on the sheet 50 (or on any other substrate described above) may also be used, such as using an external (e.g., offline) inspection system or any type of measuring instrument and / or scanner. In these embodiments, based on the information received from the external inspection system, the processor 20 is configured to initiate any suitable corrective actions and / or stop the operation of the system 10.

[0109] For purposes of illustration, the configuration of the system 10 is simplified and provided only by way of example. The components, modules, and stations described above in the printing system 10, as well as additional components and configurations, are described in detail in, for example, U.S. Pat. Nos. 9,327,496 and 9,186,884, PCT International Publications WO 2013 / 132438, WO 2013 / 132424, and WO 2017 / 208152, and U.S. Patent Application Publications 2015 / 0118503 and 2017 / 0008272, the disclosures of which patents and publications are hereby incorporated by reference in their entirety.

[0110] A specific configuration of the system 10 is shown by way of example in order to illustrate certain problems solved by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such systems. However, the embodiments of the present invention are in no way limited to this specific class of example systems, and the principles described herein can be similarly applied to any other class of printing systems.

[0111] Detecting unwanted movement of the blanket during the printing process

[0112] Figure 2A is a schematic top view showing unwanted movement of the blanket 44 during the printing process and a sensor 11 configured to detect the position of the edge of the blanket 44, in accordance with an embodiment of the present invention.

[0113] In certain cases, when the blanket 44 moves in the moving direction 94 (as described above) Figure 1 various operations associated with the printing process can cause unwanted movement of the blanket 44, for example, movement along the Y-axis orthogonal to the moving direction 94.

[0114] In principle, a zipper can be used to move the blanket in system 10, the zipper being integrated with the blanket and configured to reduce the movement of the blanket along the Y-axis. Such blankets are described, for example, in U.S. Patent Application Publications 2022 / 0357699, 2022 / 0250376, 2018 / 0126726, and 2021 / 0260869, the disclosures of which are incorporated herein by reference. However, the zipper can increase the friction between the blanket and the conveying system and can cause various malfunctions and / or registration errors during the printing process that can be implemented in system 10.

[0115] In some embodiments, the blanket 44 does not have a zipper, i.e., no integrated zipper. In this example, motorized rollers (such as but not limited to the BTD 99 and BCD 77 described above) are used to move the blanket 44. Figure 1 as described in.

[0116] In Figure 2A the example of, the blanket 44 slides along the BTD 99 having an axis 33 in the direction 31, which axis is also referred to herein as the longitudinal axis or axis of rotation of the BTD 99. It should be noted that, as Figure 2A shown, the blanket 44 is deformed due to the movement in the direction 31. When the printing area 18 of the blanket 44 moves in the moving direction 94 and passes under the image forming station 60, the printing bars 62a and 62b are configured to apply a first color and a second color to the printing area 18 of the blanket 44, respectively. In this example, the printing bars 62a and 62b are configured to apply droplets of blue and magenta inks to the same location on the surface of the blanket 44.

[0117] In the design of the image to be printed, it is expected to print a blue pattern at the position 15 on the blanket 44. In some cases, an undesired movement of the blanket 44 in the direction 31 can cause the blue pattern to be printed at the position 15a, which is offset from the expected position 15 along the Y-axis. When the printing area 18 of the blanket 44 passes under the printing bar 62b, a magenta pattern is printed at the position 16, which is intended to cover the expected position 15 of the blue pattern. Thus, the undesired movement of the blanket 44 in the direction 31 results in a C2C registration error 17 between the blue pattern and the magenta pattern.

[0118] In some embodiments, system 10 includes one or more edge sensing devices (referred to herein as sensors 11), which are configured to detect the position of the respective edges of the blanket 44. In this example, system 10 includes sensors 11a and 11c positioned on the first side of the blanket 44, and sensors 11b and 11d positioned on the second side of the blanket 44 opposite the first side.

[0119] In some embodiments, sensors 11a - 11d may include any suitable type of edge sensor. For example, a laser - based PosCon OXE7 sensor produced by Baumer Electric AG (Hummelstrasse 17, 8500 Frauenfeld, Switzerland), or a suitable ultrasonic - based sensor, or any other suitable type of sensor based on any suitable technology.

[0120] In some embodiments, each of sensors 11a - 11d is configured to send one or more signals indicating the position of the respective edge of blanket 44 to controller 54 (and / or processor 20). In some embodiments, based on the signals received from sensors 11a - 11d, controller 54 is configured to identify the deformation induced in blanket 44.

[0121] In other embodiments, system 10 may include one or more of sensors 11a - 11d arranged in any suitable combination. In a first example implementation, system 10 includes only sensor 11a for detecting the position of the respective edge of blanket 44. In a second example implementation, system 10 includes sensors 11a and 11b, and controller 54 is configured to calculate the actual size of blanket 44 near BTD 99. It should be noted that the calculated size of blanket 44 indicates the stretching level of blanket 44 (e.g., whether blanket 44 is sufficiently taut) and / or the deformation of blanket 44, which may be at least caused by the undesired movement of blanket 44 in direction 31. In a third example implementation, system 10 includes sensors 11a and 11c, and controller 54 is configured to calculate in particular (i) the actual size of the section of blanket 44 between sensors 11a and 11c, (ii) the non - uniform blanket cutting during the production process of blanket 44 (other methods for performing the same operation are described below Figure 4 ), (iii) the undesired movement of blanket 44 in direction 31, and other parameters related to the components of system 10 and the features related to blanket 44 and the installation of blanket 44 on system 10.

[0122] In alternative embodiments, the number of sensors 11 and the position of each sensor 11 are determined so as to detect any category of non - uniformity related to blanket 44 and its movement. For example, insufficient parallelism between rollers, changes in the movement of blanket 44 in the movement direction 94, the shape of blanket 44, and any other non - uniformity in system 10 can affect the movement of blanket 44 and / or the quality of image formation and image transfer, as will be described in more detail below Figure 3 herein.

[0123] Compensating for unwanted movement of the blanket by tilting the rollers of the printing system

[0124] Figure 2B is a schematic top view showing the compensation for unwanted movement of the blanket 44 during the printing process implemented in the system 10 according to an embodiment of the present invention.

[0125] As described above, the controller 54 is configured to identify the deformation induced in the blanket 44. In some embodiments, in response to detecting, based on signals received from one or more sensors 11a - 11d, a deformation caused by an unwanted movement of the blanket 44 in the direction 31 (as described above Figure 2A ), the controller 54 (and / or the processor 20) is configured to control the tilt of the BTD 99 to reduce the deformation, for example, by compensating for the unwanted movement and / or by reducing the speed of the unwanted movement.

[0126] In some embodiments, the first end of the BTD 99 is fixed (e.g., fixed to the chassis of the system 10) and serves as a pivot 14, while the second end of the BTD is movable about the pivot 14. In the Figure 2B example, the controller 54 is configured to control an actuator (as shown below Figure 3 ), which is configured to move the second end of the BTD 99 in a pre - assigned vector 19 such that the axis 33 rotates by a given angle relative to the position of the axis 33 shown above Figure 2A .

[0127] In some embodiments, when the blanket 44 moves in the movement direction 44, the tilt of the BTD 99 causes the blanket 44 to move in the direction 32 to compensate for the movement in the direction 31 shown above Figure 2A . It should be noted that the tilt of the BTD 99 is performed when the speed of the movement of the blanket 44 in the direction 31 is greater than a predefined threshold. For example, when the blanket 44 moves about 2 meters in the movement direction 94, if the blanket 44 moves about 10 μm in the direction 31, the BTD 99 does not need to be tilted. However, when the blanket 44 moves about 1 meter, if the blanket 44 moves about 1 mm in the direction 31, the BTD 99 needs to be tilted.

[0128] In some embodiments, the controller 54 (and / or the processor 20) is configured to control the amount of tilt (e.g., tilt angle) and the tilt rate of the BTD 99 to reduce the speed of movement of the blanket 44 along the Y - axis (e.g., in the above Figure 2Ain the direction 31). In the context of the present disclosure and in the claims, the term "reduce the speed of movement in a given direction" (or "reduce the rate of movement") means reducing the speed of movement in the same direction or reversing at least one component of the vector indicating the direction of the speed of movement. For example, in Figure 2A the blanket 44 is deformed due to moving in the direction 31 at a given speed. In this example, the controller 54 is configured to reduce the speed of the blanket movement in the direction 31 or reverse the direction of movement to the direction 32 shown above Figure 2B . When moving in the reversed direction (i.e., in the direction 32), the speed of the blanket 44 in the direction 31 is negative and thus is reduced relative to the speed of the blanket 44 moving in the direction 31, as shown above in Figure 2A .

[0129] In some embodiments, when the desired speed of movement of the blanket 44 along the Y-axis is obtained (e.g., below a given threshold), the controller 54 is configured to maintain the tilt angle of the BTD 99. In this example, when a sufficiently low speed of movement of the blanket along the Y-axis is obtained, the blue pattern and the magenta pattern are printed at positions 15 and 16, respectively, such that the C2C registration error (e.g., the C2C registration error 17 above Figure 2A ) is less than a predefined threshold. For example, in Figure 2A the C2C registration error 17 is about 0.1 mm, while in Figure 2B the C2C registration error between the blue pattern and the magenta pattern is less than about 10 μm.

[0130] In some embodiments, in response to detecting, based on signals received from one or more of the sensors 11a - 11d, a deformation caused by an undesired movement of the blanket 44 in the direction 31, the controller 54 (and / or the processor 20) is configured to control both: (i) the tilt angle of the BTD 99 and / or any other one or more rollers involved in the rotation of the blanket 44 (to compensate for mechanical deformation in the blanket 44), and (ii) the timing of the droplets of the printing fluid applied by one or more of the printing bars 62 of the image forming station to the blanket 44 (to compensate for the C2C registration error caused by mechanical deformation in the blanket 44).

[0131] In some embodiments, in addition to (a) mechanically based correction by tilting one or more rollers (as described above), the processor 20 and / or the controller 54 are further configured to compensate for C2C registration error and scale deformation in the printed image by applying software-based correction (as will be described in detail below), the software-based correction such as but not limited to: (i) adjusting the speed of the blanket 44 along the movement direction 94, and (ii) adjusting the timing for each of the printing bars 62 to apply the ink droplet color to the blanket 44.

[0132] In addition, in some cases, based on signals received from one or more of sensors 11a - 11d and / or from other sensors of system 11 (e.g., station 55 described above), processor 20 and / or controller 54 are configured to control imprinting station 84 to adjust (as described above) the operation of imprinting cylinder 82 and impression cylinder 90 in order to compensate for or eliminate various deformations that occur in the image printed on blanket 44. In one implementation, based on the foregoing signals, processor 20 and / or controller 54 are configured to estimate the image - to - substrate registration error (as described above), and control at least one operation selected from the list consisting of: (a) the timing of the engagement between imprinting cylinder 82 and impression cylinder 90 of imprinting station 84 to compensate for the image - to - substrate registration error, (b) the motion profile of at least one of imprinting cylinder 82 and impression cylinder 90, and (c) the size of the gap between disengaged imprinting cylinder 82 and impression cylinder 90. Figure 1 In another implementation, based on the foregoing signals, processor 20 and / or controller 54 are configured to estimate that one or more of the foregoing deformations and / or errors that have occurred on blanket 44 exceed the specifications of the printed image. Thus, processor 20 and / or controller 54 are configured to stop the operation of one or more stations of system 11, such as but not limited to (a) image forming station 60, (b) imprinting station 84, (c) one or more rollers configured to guide blanket 44, (d) one or more drying components (such as drying station 64), and (e) blanket handling station 52. For example, processor 20 and / or controller 54 are configured to prevent the engagement between imprinting cylinder 82 and impression cylinder 90 of imprinting station 84, and / or stop the application of ink droplets through one or more printing bars 62 of image forming station 60. Figure 1 In another implementation, based on the foregoing signals, processor 20 and / or controller 54 are configured to estimate that one or more of the foregoing deformations and / or errors that have occurred on blanket 44 exceed the specifications of the printed image. Thus, processor 20 and / or controller 54 are configured to stop the operation of one or more stations of system 11, such as but not limited to (a) image forming station 60, (b) imprinting station 84, (c) one or more rollers configured to guide blanket 44, (d) one or more drying components (such as drying station 64), and (e) blanket handling station 52. For example, processor 20 and / or controller 54 are configured to prevent the engagement between imprinting cylinder 82 and impression cylinder 90 of imprinting station 84, and / or stop the application of ink droplets through one or more printing bars 62 of image forming station 60. Figure 1 In another implementation, based on the foregoing signals, processor 20 and / or controller 54 are configured to estimate that one or more of the foregoing deformations and / or errors that have occurred on blanket 44 exceed the specifications of the printed image. Thus, processor 20 and / or controller 54 are configured to stop the operation of one or more stations of system 11, such as but not limited to (a) image forming station 60, (b) imprinting station 84, (c) one or more rollers configured to guide blanket 44, (d) one or more drying components (such as drying station 64), and (e) blanket handling station 52. For example, processor 20 and / or controller 54 are configured to prevent the engagement between imprinting cylinder 82 and impression cylinder 90 of imprinting station 84, and / or stop the application of ink droplets through one or more printing bars 62 of image forming station 60.

[0133] In another implementation, based on the foregoing signals, processor 20 and / or controller 54 are configured to estimate that one or more of the foregoing deformations and / or errors that have occurred on blanket 44 exceed the specifications of the printed image. Thus, processor 20 and / or controller 54 are configured to stop the operation of one or more stations of system 11, such as but not limited to (a) image forming station 60, (b) imprinting station 84, (c) one or more rollers configured to guide blanket 44, (d) one or more drying components (such as drying station 64), and (e) blanket handling station 52. For example, processor 20 and / or controller 54 are configured to prevent the engagement between imprinting cylinder 82 and impression cylinder 90 of imprinting station 84, and / or stop the application of ink droplets through one or more printing bars 62 of image forming station 60.

[0134] Additionally or alternatively, corrective actions can be implemented proactively rather than in response to detected deformations. Proactive corrective actions can be implemented based on a pre - characterization of the system before starting a printing job, for example, by running a test job under the same conditions as the expected printing job. In addition, some deformations are caused by the heating of blanket 44 and other components of system 10. As described above, heating can be achieved by infrared radiation applied to blanket 44 by heater 66 and / or drying station 64.

[0135] In other embodiments, controller 54 is configured to apply tilts to one or more selected rollers of system 10, for example, tilting both BTD 99 and BCD 77 simultaneously, as described in detail below Figure 3 In other embodiments, controller 54 is configured to apply tilts to one or more selected rollers of system 10, for example, tilting both BTD 99 and BCD 77 simultaneously, as described in detail below

[0136] In the context of the present disclosure and in the claims, embodiments related to any computing and / or control operations may be implemented using the controller 54 or the processor 20 or using any suitable combination of the controller 54 and the processor 20.

[0137] It should be noted that Figure 2B the configurations presented in [[ ]] are simplified for clarity of concept and are provided only by way of example to illustrate embodiments of the present invention.

[0138] Figure 3 is a schematic diagram showing the control of the moving speed of the blanket 44 along the Y-axis according to an embodiment of the present invention. Figure 3 describes embodiments in which the techniques shown above Figure 2B are applied to one or more selected components of the system 10 to reduce errors in the printed images in the system 10.

[0139] In some embodiments, the system 10 includes a BTD driver 199, which is controlled by the controller 54 and is configured to drive the BTD 99 (e.g., based on signals received from one or more of the position encoders described above Figure 1 ). The system 10 also includes a suitable actuator, herein referred to as actuator 23, which is controlled by the controller 54 or a BTD guide (e.g., a slave of the controller 54). In the present example, the actuator 23 includes a linear actuator made of a motorized screw, which is configured to move the non-fixed end of the BTD 99 (also referred to as the second side above Figure 2B ) in a controlled direction 24. It should be noted that the direction 24 is shown using a double-headed arrow because the actuator 23 is configured to move back and forth (e.g., along the X-axis).

[0140] In Figure 3 the example of [[ ]], each of the BTD 99, BCD 77, and idler 76 has a fixed end (also referred to as the first end herein) and a non-fixed end (also referred to as the second end herein), which is configured to be moved by a suitable actuator (such as actuator 23), as will be described in detail herein.

[0141] In some embodiments, the system 10 includes a BCD driver 177, which is controlled by the controller 54 and is configured to drive the BCD 77 based on signals received from one or more of the position encoders described above Figure 1 . The system 10 also includes a motorized actuator 25, which has similar characteristics to the actuator 23 and is controlled using the controller 54 or a BCD guide (a slave of the controller 54).

[0142] In some embodiments, the actuator 25 is configured to move the non-fixed end (i.e., the second side) of the BCD 77 in the controlled direction 26. It should be noted that the direction 26 is shown using a two-way arrow because the actuator 25 is configured to move back and forth (e.g., along the X-axis).

[0143] In some embodiments, the idler 76 is not motorized and is configured to rotate about its longitudinal axis by the blanket 44 when the blanket 44 moves. The system 10 further includes a motorized actuator 27 having similar characteristics to the actuator 23 and being controlled by the controller 54 or using an idler guide 176 (e.g., a subordinate of the controller 54).

[0144] In some embodiments, the actuator 27 is configured to move the non-fixed end (i.e., the second side) of the idler 76 in the controlled direction 28. It should be noted that the direction 28 is shown using a two-way arrow because the actuator 27 is configured to move back and forth (e.g., along the X-axis).

[0145] In this example, the first ends of the idler 76, BCD 77, and BTD 99 are all fixed near the edge 30 of the blanket 44, while the actuators 23, 25, and 27 are respectively positioned near the second ends of the idler 76, BCD 77, and BTD 99, and the second ends are positioned near the edge 29 of the blanket 44. In other embodiments, the ends of at least one of the idler 76, BCD 77, and BTD 99 can be switched, and the positions of the corresponding actuators can be changed respectively. For example, both the non-fixed end of the idler 76 and the actuator 27 can be positioned near the edge 30 of the blanket 44.

[0146] In some embodiments, the system 10 includes additional components, such as but not limited to a floating roller driver 174 (configured to drive the floating roller 74) and an idler 76a, which may be related to the movement of the blanket 44 but are not described in the embodiments of the present invention.

[0147] In some embodiments, the blanket 44 moves along Figure 1 and Figure 3 the annular continuous path shown, and the system 10 includes a plurality of edge sensors, such as the sensors 11a - 11d shown above Figure 2A and Figure 2B in. The system 10 includes additional sensors (described below), which are distributed along the continuous path of the blanket 44 in different sections of the system 10. In Figure 3In the example, sensors 11a and 11b are positioned near BTD 99, sensors 11c and 11d are positioned near BCD 77, sensor 11e is positioned between idler pulley 76a and impression station 84, sensor 11f is positioned between impression station 84 and blanket handling station 52, and sensor 11g is positioned between blanket handling station 52 and idler pulley 76. Sensors 11a and 11c are configured to detect the position of edge 30, and sensors 11b and 11d are configured to detect the position of edge 29.

[0148] In one embodiment, each of sensors 11e, 11f, and 11g may include one sensor positioned near edge 29 or 30 for detecting the position of the corresponding edge. In another embodiment, one or more of sensors 11e, 11f, and 11g include two sensors respectively positioned near edges 29 and 30.

[0149] In principle, every interaction between blanket 44 and another element or component can affect the moving speed of blanket 44 along the Y-axis. For example, unwanted movement along the Y-axis can be caused by: (i) the accidental tilt of one or more rollers (e.g., BTD 99, BCD 77, idler pulleys 76 and 76a, roller 78), one or more rollers of blanket handling station 52 (as will be described in more detail below), or one or both of pressure cylinder 90 and impression cylinder 82, or another element placed in contact with both edges 29 and 30, (ii) at least two rollers (usually very close, e.g., BTD 99 and idler pulley 76) not being parallel to each other, (iii) a deviation in the contact force between blanket 44 and the element placed in contact with it. For example, replacing the spinner (i.e., scraping blade, not shown) in blanket handling station 52 can change the force applied to blanket 44 and can cause blanket 44 to move along the Y-axis, (iv) non-uniform thermal expansion of the element placed in contact with blanket 44 along the Y-axis. For example, the first end of a roller expands more than the second end, (v) any other reason that can affect the force applied to blanket 44.

[0150] In some embodiments, based on the signals received from one or both of sensors 11a and 11b, controller 54 is configured to estimate the C2C registration error that may be caused by the movement of blanket 44 along the Y-axis, as described above in Figure 2A For example, blanket 44 may move along the Y-axis in the following cases: (i) BTD 99 is accidentally tilted (e.g., when installed on system 10), (ii) BTD 99 and BCD 77 are not parallel to each other, (iii) BTD 99 and idler pulley 76 are not parallel to each other, (iv) non-uniform thermal expansion of the ends of BTD 99, or for any other reason.

[0151] In some embodiments, based on signals received from one or more of sensors 11c, 11d, and 11e, controller 54 is configured to estimate the image-to-substrate (I2S) registration error that may be caused by movement of blanket 44 along the Y-axis. For example, the blanket may move in the following cases: (i) at least one of BCD 77, idler roller 74, and idler pulley 76a is inadvertently tilted (e.g., when mounted on system 10), (ii) two or more of BCD 77, idler roller 74, and idler pulley 76a are not parallel to each other, (iii) non-uniform thermal expansion at the ends of at least one of BCD 77, idler roller 74, and idler pulley 76a, and (iv) improper installation or operational failure of one or both of impression cylinder 90 and blanket cylinder 82, especially when engaged while imprinting an ink image onto the surface of sheet 50, as described above Figure 1 as described.

[0152] As described above, blade replacement in the rotator (not shown) of blanket handling station 52 can change the force applied to blanket 44 and can cause movement of blanket 44 along the Y-axis. It should be noted that since the specifications for C2C registration are generally more stringent than those for I2S specifications, controller 54 is configured to control actuators 23 and 25 to apply different tilt angles and different tilt rates to BTD 99 and BCD 77, respectively, in order to control the movement of blanket 44 along the Y-axis and / or reduce deformation in blanket 44.

[0153] In some embodiments, controller 54 is configured to apply a tilt to one or more selected rollers of system 10 (using the respective actuators). For example, controller 54 can apply a tilt to both BTD 99 and BCD 77 simultaneously. Alternatively, controller 54 is configured to apply a tilt to BCD 77 without applying a tilt to BTD 99, or controller 54 can use any other suitable tilt scheme applied to one or more selected rollers of system 10. It should be noted that the tilt scheme is determined based on a known force applied to blanket 44 or in response to detecting a corresponding movement profile along the Y-axis.

[0154] In some embodiments, controller 54 is configured to maintain a look-up table (LUT) that includes one or more known deformations caused by one or more operations implemented in system 10, respectively. For example, blade replacement in blanket handling station 52 can change the force applied to blanket 44 in a known manner. In such an embodiment, the LUT can be used for feedforward active correction. For example, controller 54 can control actuator 27 to tilt idler pulley 76 immediately after blade replacement in order to actively reduce or eliminate movement of blanket 44 along the Y-axis due to blade replacement.

[0155] In other embodiments, if the BTD 99 is not correctly assembled on the system 10, the BTD 99 may be tilted and not parallel to at least one of the idler pulley 76 and the BCD 77. In such embodiments, the LUT may include C2C registration errors associated with incorrect assembly of the BTD 99, and the controller 54 is configured to: (i) display a message indicating incorrect assembly on the display 34, and (ii) if the C2C error is greater than a predefined threshold, maintain the operation of the system 10 or control the actuator 23 to tilt the BTD 99 according to the LUT to reduce known deformations, such as C2C registration.

[0156] In some embodiments, the controller 54 is configured to control the actuator 23 to tilt the BTD 99 based on the LUT and signals received from one or more sensors 11a - 11g. In this way, the controller 54 is configured to compensate for C2C registration errors caused by deformation of the blanket 44, for example, by tilting at least one of the BCD 77, the BTD 99, and the idler pulley 76 of the system 10. The compensation can be implemented actively (based on pre - characterization of the system 10 when running an expected printing job) and / or passively (in response to signals received from at least one of the sensors 11a - 11g). Additionally, by controlling the tilt levels of the BCD 77, the BTD 99, the idler pulley 76, and optionally other rollers of the system 10, the controller 54 is configured to control the guiding of the blanket 44 and compensate for deformations in the blanket 44 and / or the components used to guide the blanket 44.

[0157] In some embodiments, controlling the movement of the blanket 44 along the Y - axis can be used to reduce the occurrence of memory effects during the printing process. The term "memory effect" refers to the characteristics of repeating printed images at one or more identical positions on the surface of the blanket 44. The memory effect can cause the outline of an image to appear in subsequent printing of another image. The memory effect and embodiments for reducing its occurrence are described, for example, in U.S. Provisional Patent Application 63 / 210,507 and PCT International Publication WO 2022 / 263989, the disclosures of which are incorporated herein by reference. In some embodiments, the disclosed techniques can be used to change the position of the image formed on the blanket 44 and thus to reduce the memory effect as described above.

[0158] In other embodiments, instead of or in addition to the LUT, the controller 54 is configured to maintain a neural network (NN) (not shown), which is trained to identify one or more deformations in the blanket 44, such as the deformations Figure 2A and Figure 2B shown above.

[0159] In some embodiments, the NN can include any suitable type of NN, such as but not limited to a convolutional NN (CNN) or a recurrent NN (RNN) or a combination thereof, which can be trained using supervised or unsupervised training techniques. For example, the NN can be trained based on known events to identify known deformations. Based on the trained NN and one or more signals received from one or more of sensors 11a - 11g, the controller 54 is configured to control one or more actuators of the system 10 (e.g., one or more of actuators 23, 25, and 27) to apply an inclination to the corresponding rollers (e.g., BTD 99, BCD 77, and idler 76) to reduce one or more of the identified known or unknown deformations.

[0160] Additionally or alternatively, the processor 20 can include at least one of a LUT and an NN, and is configured to control one or more of the actuators of the system 10 to apply an inclination to the corresponding rollers to reduce one or more of the identified known or unknown deformations, as described above for the controller 54.

[0161] Figure 3 The configuration is simplified for clarity of concept and is shown by way of example to illustrate certain problems solved by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of the system 10. However, embodiments of the present invention are in no way limited to this particular class of example systems, and the principles described herein are similarly applicable to any other class of printing systems using flexible ITMs or any other class of ITMs. Additionally, Figure 2B and Figure 3 the techniques can, with the necessary modifications, be used in any other system that uses rollers or other suitable techniques to which the disclosed embodiments can be applied to move members, and in particular flexible members.

[0162] Distinguishing blanket cutting errors and unwanted movement of the blanket

[0163] Figure 4 is a schematic side view of a section 47 of the blanket 44 according to an embodiment of the present invention and graphs 71 and 72 for showing a method for distinguishing between blanket cutting errors and unwanted movement of the blanket. In the context of the present disclosure and in the claims, the term "blanket cutting error" refers to the cutting of the edge (e.g., edge 29) of the blanket 44 not being parallel to the X - axis.

[0164] In Figure 4In the example, when the blanket 44 moves in the direction 94 (e.g., parallel to the X-axis), a given edge sensor 11 (e.g., sensor 11b or 11d) can detect the movement of the edge 29 of the section 47 along the Y-axis. In some cases, the movement of the edge 29 of the section 47 along the Y-axis may be due to the roughness of the edge 29, which is caused during the production process of the blanket 44. For example, at least in the section 47, insufficient fabric cutting accuracy of the blanket 44 can cause one or more sections of the edge 29 to be non-parallel to the X-axis. In other cases, the signal received from the sensor 11 can indicate the movement of the blanket 44 along the Y-axis, as described above, for example, in Figure 2A as shown.

[0165] It should be noted that in order to correct the deformation caused by the movement along the Y-axis, the controller 54 must filter out the contribution of the blanket cutting error to quantify the movement speed on the Y-axis based on the signal received from the sensor 11, as described above in Figure 2B and Figure 3 described.

[0166] Now refer to FIGS. 71 and 72. The graph axis 73 shows the detected position (e.g., displacement) of the edge 29 on the Y-axis relative to a reference point, and the graph axis 75 shows the time when the blanket 44 moves in the direction 94. In other words, FIGS. 71 and 72 show the movement of the edge 29 over time detected during the printing process. In the context of the present disclosure, the term "detected movement" refers to the movement of the edge 29 detected based on the signal received from the sensor 11. It should be noted that the detected movement can indicate the physical movement of the blanket 44 along the Y-axis (e.g., as described above in Figure 2A ), or the blanket cutting error described above, or any combination thereof.

[0167] Now refer to FIG. 71. During the first revolution of the blanket 44, shown as 81, the detected position of the edge 29 of the section 47 is outlined using the line 85a. Similarly, during the second revolution of the blanket 44 (which immediately follows the first revolution and is shown as 83), the detected position of the edge 29 of the section 47 is outlined using the line 85b. The terms "first revolution" and "second revolution" refer to the "nth revolution" and the "(n + 1)th revolution" of the blanket 44, respectively. It should be noted that if the step size of the movement speed of the blanket 44 on the Y-axis is less than a given threshold (e.g., less than about 0.1 mm per revolution), then the second revolution can refer to the "(n + 10)th revolution" of the blanket 44 in the system 10.

[0168] In Figure 4 the example, the dashed line 87 indicates the movement of the detected point 91 on the axis 73. In FIG. 71, the movement values of the point 91 detected in two revolutions are the same, such that both the lines 85a and 85b are tangent to the dashed line 87.

[0169] Referring now to FIG. 72, where lines 85c and 85d show the detection positions of the edges 29 of the middle sections 47 of the first and second revolutions of the blanket 44, as described above. It should be noted that line 85a and line 85c are the same, so the point 91 of line 85c is tangent to the dashed line 87, but the point 91 of line 85d is tangent to the dashed line 89 located at a distance 93 from the dashed line 87. Additionally, the point 95 of the edge 29 is positioned at a distance 97 from the point 91.

[0170] In some embodiments, the controller 54 is configured to detect movement of the blanket 44 along the Y-axis by comparing the positions of the blanket 44 detected at the same point on the edge 29. In the example of FIG. 72, the distance 97 indicates a blanket cutting error in the edge 29, and the distance 93 indicates movement of the blanket along the Y-axis. In such an embodiment, based on the distance 93, the controller 54 is configured to control one or more actuators of the system 10 to tilt the corresponding rollers of the system 10 to reduce the deformation caused in the blanket 44 due to movement along the Y-axis.

[0171] In some embodiments, based on Figure 4 the techniques described in, the controller 54 is configured to identify that the distance 97 indicates a blanket cutting error in the edge 29. Thus, the controller 54 does not control any actuators of the system 10 to apply tilting of the corresponding rollers because the distance 97 does not indicate any movement of the edge 29 along the Y-axis.

[0172] In other embodiments, the system 10 may include at least first and second edge sensors 11 located at first and second corresponding positions along the edge 29 of the section 47, respectively. In such an embodiment, the controller 54 is configured to calculate the blanket cutting error by comparing a first signal and a second signal received from the first and second edge sensors 11, respectively.

[0173] Figure 5 is a flowchart schematically showing a method for reducing deformation in a blanket 44 that undesirably moves along the Y-axis during a printing process, in accordance with an embodiment of the present invention.

[0174] In some embodiments, the method begins with a blanket movement step 100, where the blanket 44 is moved along a direction 94 (generally parallel to the X-axis of the system 10) using a first roller and a second roller (such as but not limited to BTD 99 and BCD 77), as described above Figure 1 in.

[0175] In some embodiments, the controller 54 receives a first signal and a second signal from two or more sensors 11, the first signal and the second signal indicating the speed of movement of the blanket 44 along the Y-axis in the first and second sections of the printing system 10. For example, the controller 54 receives: (i) a first signal from a sensor 11a located near the BTD 99, and (ii) a second signal from a sensor 11c located near the BCD 77, as described above Figure 2B and Figure 3 above.

[0176] In some embodiments, in a first decision step 102, the controller 54 checks, for example based on the signal received from the sensor 11a, whether an edge 30 of the blanket 44 is moving along the Y-axis at a speed greater than a pre-assigned threshold (e.g., the blanket 44 moves approximately 1 millimeter per revolution).

[0177] Similarly, in a second decision step 104, the controller 54 checks, for example based on the signal received from the sensor 11c, whether an edge 30 of the blanket 44 is moving along the Y-axis at a speed greater than a pre-assigned threshold (e.g., the blanket 44 moves approximately 5 millimeters per revolution).

[0178] In some embodiments, the threshold of step 104 is related to a specified I2S registration of the system 10, while the threshold of step 102 is related to a specified C2C registration of the system 10, which is generally more stringent than the I2S specification. In other embodiments, the thresholds of steps 102 and 104 may be similar.

[0179] In some embodiments, if the speed of movement in step 102 is less than the threshold, the controller 54 and the processor 20 control the system 10 to continue the printing process described above Figure 1 above.

[0180] In other embodiments, if the speed of movement in step 102 is greater than the threshold, the method proceeds to the BTD tilt step 106, where the controller 54 controls the actuator 23 to tilt the BTD 99 as the blanket 44 moves along the X-axis to reduce the speed of movement of the blanket along the Y-axis, as described above Figure 3 above.

[0181] In some embodiments, the controller 54 receives, for example, a signal (referred to herein as a third signal) from the sensor 11a that indicates a reduction in the speed of movement of the blanket along the Y-axis near the BTD 99 (in response to applying a tilt to the BTD 99), as described in detail above Figure 3 above.

[0182] In the third decision step 108, the controller 54 checks whether the edge 30 of the blanket 44 is moving along the Y-axis at a speed greater than the pre-assigned threshold of the above step 102, based on, for example, the third signal received from the sensor 11c.

[0183] In some embodiments, if the moving speed of the blanket 44 along the Y-axis is greater than the threshold, the method loops back to step 106, and the controller 54 controls the actuator 23 to adjust the tilt of the BTD 99 to further reduce the moving speed of the blanket 44 along the Y-axis near the BTD 99.

[0184] In other embodiments, if the moving speed of the blanket 44 along the Y-axis is less than the threshold, the method proceeds to the first tilt holding step 110, where the controller 54 controls the actuator 23 to hold the tilt of the BTD 99 such that the movement of the blanket 44 along the Y-axis is stable, for example, with a small amplitude fluctuation near a given value.

[0185] In some embodiments, steps 102, 106, 108, and 110 can be applied, with necessary modifications, to one or more additional rollers of the system 10. In Figure 5 the example, steps 112, 114, and 116 correspond to steps 106, 108, and 110 respectively, and are applied to the BCD 77 and the actuator 25, as will be described in detail herein. It should be noted that the same technique can be applied to the idler pulley 76, the sensor 11g, and the actuator 27, or any other suitable component of the system 10.

[0186] In some embodiments, if the moving speed in step 104 is less than the threshold, the controller 54 and the processor 20 control the system 10 to continue the printing process described above Figure 1 above.

[0187] In other embodiments, if the moving speed in step 104 is greater than the threshold, the method proceeds to the BCD tilt step 112, where the controller 54 controls the actuator 25 to tilt the BCD 77 when the blanket 44 moves along the X-axis to reduce the moving speed of the blanket along the Y-axis, as described above Figure 3 above.

[0188] In some embodiments, the controller 54 receives, for example, a signal (referred to herein as the fourth signal) from the sensor 11c, which indicates a reduction in the moving speed of the blanket along the Y-axis near the BCD 77 (in response to applying a tilt to the BCD 77), as described in detail above Figure 3 above.

[0189] In the fourth decision step 114, the controller 54 checks, for example, based on the third signal received from the sensor 11c, whether the edge 30 of the blanket 44 is moving along the Y-axis at a speed greater than the pre-assigned threshold of the above step 102.

[0190] In some embodiments, if the moving speed of the blanket 44 along the Y-axis is greater than the threshold of step 104, the method loops back to step 112, and the controller 54 controls the actuator 25 to adjust the tilt of the BCD 77 to further reduce the moving speed of the blanket 44 along the Y-axis near the BCD 77.

[0191] In other embodiments, if the moving speed of the blanket 44 along the Y-axis is less than the threshold, the method proceeds to the second tilt holding step 116, where the controller 54 controls the actuator 25 to hold the tilt of the BCD 77 so that the movement of the blanket 44 along the Y-axis is stable, for example, with small fluctuations around a given value, which is generally different from the given value of the above step 110.

[0192] In some embodiments, if the moving speed of the blanket along the Y-axis is less than the threshold of step 102 in steps 102 and 108, and if the moving speed of the blanket along the Y-axis is less than the threshold of step 104 in steps 104 and 114, the controller 54 and the processor 20 control the system 10 to continue the printing process as described in the above steps 102 and 104. Additionally, during the printing process, the method proceeds to the fifth decision step 118, where the processor 20 or the controller 54 checks whether the printing job is completed.

[0193] In some embodiments, if the printing job is not completed, the method loops back to step 100, and if the printing job is completed, the method proceeds to the end step 120, which ends the method and implements various standard operations for terminating the printing process in the system 10.

[0194] Figure 6A is a schematic top view according to an embodiment of the present invention, showing the alignment between the movement of the blanket 44 and the printing patterns of the printing bars 62 of the system 10 at positions 15 and 16.

[0195] In some embodiments, when the blanket 44 is aligned with the guide roller of the system 10, and when a sufficiently low movement of the blanket along the Y-axis is obtained (e.g., almost no movement), the blue pattern and the magenta pattern are printed at positions 15 and 16 respectively, such that the C2C registration error is less than a predefined threshold. Figure 6AIn the example, BCD 77 and BTD 99 appear to be parallel to each other and parallel to the Y-axis, and the edges 29 and 30 of the blanket 44 appear to (i) be parallel to each other and parallel to the X-axis and thus (ii) be orthogonal to BCD 77, BTD 99, and the Y-axis.

[0196] In some cases, BCD 77 and BTD 99 may not be positioned parallel to each other, and / or one or both of the edges 29 and 30 of the blanket 44 may not be positioned orthogonally to one or both of BCD 77 and BTD 99. In some embodiments, based on signals received from sensors 11 (e.g., sensors 11b and 11d), the controller 54 is configured to control actuators 23 and 25 to compensate for deviations in the above-mentioned parallelism and / or orthogonality so as to obtain a C2C registration error less than a predefined threshold. In other words, even in the case of deviation from the foregoing parallelism and / or orthogonality, the controller 54 is configured to obtain the desired C2C registration level, e.g., by controlling the timing of applying the printing fluid to the surface of the blanket 44 or using any other suitable compensation technique.

[0197] Figure 6B is a schematic top view according to an embodiment of the present invention, showing the detection of unwanted deformations in the blanket 44 and / or in the patterns printed by the system 10.

[0198] In Figure 6B the example, overheating of the blanket 44 (and its guiding members) causes thermal expansion of the blanket 44, which results in the BTD 99 tilting at an angle 35 about the BTD driver 199. This tilt causes the C2C registration error 17, as shown and described above Figure 2A above.

[0199] In some embodiments, the driver 119 includes a rotary encoder configured to generate a signal indicating the angle 35 of the BTD 99. Based on the signal received from the driver 119, the controller 54 and / or the processor 20 are configured to: (i) estimate the deformation in the blanket 44 and the C2C registration error 17, and (ii) control correction actions such as, but not limited to, the correction actions described above Figures 2A to 5 above.

[0200] In addition, in certain cases, the BTD 99 may also be deformed (e.g., having an arc shape). In some embodiments, based on the signal received from the driver 119, the controller 54 and / or the processor 20 are configured to estimate the level of deformation in the BTD 99 and determine correction actions such as replacing the BTD 99.

[0201] Additionally or alternatively, the processor 20 is configured to receive, for example, from the slave station 55 a signal indicative of the C2C registration error 17 such that, based on the estimated C2C registration error 17, the processor 20 and / or the controller 54 is configured to determine a correction action, such as any one of the above-described correction actions.

[0202] Figure 7 is a schematic top view according to an embodiment of the present invention, showing the detection of deformation in the side wall 36 of the chassis of the system 10. The term "side wall" refers to any kind of rod or another part of the chassis of the system 10, and for the sake of conceptual clarity, other parts of the chassis are removed from Figure 7 therefrom.

[0203] In some embodiments, the printing rods 62a and 62b coupled to the side wall 36 are configured to apply droplets of cyan and magenta inks, respectively, to the same positions on the surface of the blanket 44.

[0204] In this example, the side wall 36 is deformed relative to the axis 41, which indicates the longitudinal axis of the original shape (before deformation) of the side wall 36. Due to the deformation in the side wall 36, at least the printing rods 62a and 62b have been displaced, and thus cyan and magenta inks can be directed to positions 15a and 16a, respectively. It should be noted that positions 15a and 16a have corresponding offsets relative to the expected positions 15 and 16 of the droplets (and the pattern formed by the droplets), as shown above Figure 2A and Figure 2B therein. Accordingly, the offset between positions 15 and 15a and the offset between positions 16 and 16a result in the C2C registration error 39.

[0205] In some embodiments, in addition to or instead of the sensors 11a - 11g, the system 11 includes at least edge sensors 37 and 38, which are coupled to the side wall 36 and are long enough to generate a first signal indicative of the position of the edge 29 and a second signal indicative of the position of the side wall 36.

[0206] In some embodiments, based on the first and second signals received from each of the edge sensors 37 and 38, the processor 20 and / or the controller 54 is configured to: (i) estimate the deformation in the side wall 36, and (ii) control at least the printing rods 62a and 62b to direct the droplets to positions 15 and 16, respectively, or to any other positions compensating for the C2C registration 39, and thereby, reduce the C2C registration level below a predefined threshold.

[0207] Additionally or alternatively, the processor 20 and / or the controller 54 is configured to receive from the sensors 11a - 11g additional signals indicative of the deformation in the blanket 44 (and / or at least in the BCD 77 and / or the BTD 99), as above Figures 2A to 5As described therein. Based on signals from sensors 11a - 11g and sensors 37 and 38, processor 20 and / or controller 54 are configured to control at least print bars 62a and 62b to direct droplets to positions 15 and 16, respectively, or to any other position compensating for C2C registration 39, and thereby, reduce the C2C registration level to less than the aforementioned predefined threshold.

[0208] In some embodiments, blanket 44 includes markings that indicate corresponding positions on blanket 44, and more specifically, the positions of these markings indicate the starting page position on the surface of blanket 44. In the context of the present disclosure and in the claims, the term "starting page" refers to the position on blanket 44 where an image begins to be printed (e.g., a corner of the image intended to be printed).

[0209] In some embodiments, the markings are formed on or in one or both of edges 29 and 30. In this example, the markings are formed at predefined (generally equidistant) positions along one or both of edges 29 and 30 and serve as a scale for a position encoder along the X - axis of blanket 44, as will be described in more detail below. These markings are generally similar along edges 29 and 30, but in this example, the markings 122a, 122b, 124a, 124b, and 126 shown on edge 30 are different from each other, as will be described below.

[0210] In some embodiments, if markings are formed on or in both of the two edges 29 and 30, and based on signals received from sensors (e.g., sensors 11a - 11d and / or sensors 37 and 38) located at both edges and detecting the markings at both edges, processor 20 and / or controller 54 are configured to detect and correct additional deformations (such as but not limited to torsional deformations) in blanket 44, which are based on signals received from sensors on both sides of blanket 44.

[0211] In some embodiments, the indicia 122a, 122b, 124a, 124b, and 126 may be formed as stickers, labels, or logos disposed on one or both edges 29 and 30. In other embodiments, the indicia 122a, 122b, 124a, 124b, and 126 may include openings formed in the blanket 44 by mechanical splicing, or laser ablation, or chemical etching. In alternative embodiments, the indicia 122a, 122b, 124a, 124b, and 126 may be printed by the system 11 or using any other suitable printing system. In the case of stickers, labels, logos, and printing, the indicia 122a, 122b, 124a, 124b, and 126 may be formed on: (i) the outer surface of the blanket 44 (receiving droplets of printing fluid), (ii) the inner surface of the blanket 44 (facing the outer surface but not receiving droplets of printing fluid), or (iii) a suitable combination of the outer and inner surfaces.

[0212] Reference is now made to inset 51 at 122a, which shows right-angled trapezoids 56a and 56b of similar size and shape. Trapezoides 56a and 56b are aligned along the X-axis and have sides 59a and 59b, respectively, which are orthogonal to bases 46 and 48. Trapezoides 56a and 56b also include sides 61a and 61b, respectively (also referred to herein as diagonal sides at predefined angles relative to the X-axis).

[0213] In some embodiments, when the blanket 44 moves along the X-axis, the aforementioned sensors (such as sensors 37 and 38) are configured to detect the edges 59a and 59b and the edges 61a and 61b. In some embodiments, before starting the printing process, the blanket 44 is moved several turns to learn the positions of the marks 122a, 122b, 124a, 124b and 126 on the blanket 44 (and optionally relative to the predefined positions in the blanket 44 and / or the system 11). In such embodiments, the processor 20 and / or the controller 54 are configured to receive signals indicating the positions of the edges 59a and 59b and the edges 61a and 61b from the sensors 37 and 38. Subsequently, during the printing process and based on the aforementioned learning, the processor 20 and / or the controller 54 are configured to estimate the speed of the blanket 44 along the X-axis and the deformation of the blanket 44 along the Y-axis, as will be described herein. It should be noted that the same structure is formed along the edge 30, such as in the mark 122b.

[0214] In some embodiments, based on the known distance between edges 59a and 59b (along the X-axis), processor 20 and / or controller 54 are configured to estimate the speed of blanket 44 along the X-axis. In such an embodiment, edges 59a and 59b serve as position encoders at one or both of edges 29 and 30 of blanket 44, which can be used to control the position and speed of blanket 44 along the X-axis. Thus, the distance between the marks is determined by the control requirements of the position and speed of blanket 44. In this way, the marks can be formed every few millimeters, or every few tens of micrometers, or at any other suitable distance between adjacent marks.

[0215] In some embodiments, based on the signals received from sensors 37 and 38, processor 20 and / or controller 54 are configured to control the ejection time of each pixel and all colors in the image printed by respective printing bars 62. Based on the estimated position and speed of blanket 44, processor 20 and / or controller 54 are configured to control the appropriate position of each of the printed color images and the appropriate scale (generally similar) in all the printed color images, respectively.

[0216] In some embodiments, in addition to or instead of the marks formed along the X-axis whose structure and function are described in detail above, blanket 44 may further include suitable marks formed along the Y-axis. These marks may have the same size and / or shape as marks 122, 124, and 126 (described above), but may have any other suitable size and / or shape. For example, (i) a mark similar to mark 122a, where trapezoids 56a and 56b are rotated 90 degrees, (ii) a mark similar to mark 124b, where trapezoids 58a and 58b are rotated 90 degrees, and (iii) any other suitable marks, such as, including bars (not shown) having any suitable size along the X-axis and Y-axis, and generally (a) parallel to the X-axis and (b) arranged along the Y-axis using any pitch size suitable for detecting additional deformations such as, but not limited to, scale deformations along the Y-axis. In such an embodiment, based on these marks, processor 20 and / or controller 54 are configured to detect and correct scale deformations (and other categories of deformations) along the Y-axis in at least one and generally all of the color images of the image printed by system 11. For example, the correction can be implemented by controlling at least one of actuators 23, 25, and 27, as described in detail above Figure 3 above.

[0217] Additionally or alternatively, the encoder may be implemented using a marker 126 having a polygonal shape (e.g., rectangular or square), and the sensitivity of the encoder is determined by the distance between the sides of the marker 126 that are parallel to the Y-axis (e.g., the side 59 parallel to the marker 122). It should be noted that in some cases, the intensity of the signals received from sensors 37 and 38 has undesired noise, e.g., caused by residues of printing fluids and other categories of materials. In some embodiments, based on the signals received from sensors 37 and 38, the processor 20 and / or the controller 54 are configured to estimate the centerline (e.g., the average position along the X-axis) between adjacent sides that are parallel to the Y-axis. Averaging the signals can reduce errors in position readings due to the above-mentioned noise.

[0218] In some embodiments, based on the estimation (along the X-axis) of (i) the reconstruction portion 63a of the side 30 passing between the sides 59a and 61a and (ii) the reconstruction portion 63b of the side 30 passing between the sides 59b and 61b, the processor 20 and / or the controller 54 are configured to estimate the deformation of the blanket 44 along the Y-axis. Due to the (same) slopes of the sides 61a and 61b respectively, the sizes of the reconstruction portions 63a and 63b along the X-axis are different.

[0219] It should be noted that the deformation in the blanket 44 is a physical phenomenon and thus typically occurs between structures that are not too close to each other. In this example, the deformation along the Y-axis causes the side 30 to move between (i) the reconstruction portion 63a in the marker 122a and (ii) the reconstruction portion 63b in the marker 122b. In other words, based on the detection (by sensors 37 and 38) of the sides 59 and 61 in the marker 122, the processor 20 and / or the controller 54 are configured to estimate: (i) the sizes of the reconstruction portions 63a and 63b along the X-axis and, therefrom, (ii) the deformation in the blanket 44 along the Y-axis.

[0220] Now referring to illustration 53 of the marker 124b, which shows isosceles trapezoids 58a and 58b having similar sizes and shapes. The isosceles trapezoids 58a and 58b are aligned along the X-axis and have (i) sides 67a and 69a and (ii) sides 67b and 69b respectively. In the context of the present disclosure and in the claims, the sides 67a, 67b, 69a, and 69b are also referred to herein as diagonal sides, which are at a predefined angle with respect to the X-axis (usually different from the predefined angle of the sides 61a and 61b).

[0221] In some embodiments, when the blanket 44 moves along the X-axis, the deformation along the Y-axis causes the reconstructed portions 65a and 65b (of the blanket edge 30) to be detected in the isosceles trapezoids 58a and 58b of the markers 124a and 124b, respectively. The size of the reconstructed portions 65a and 65b along the X-axis is determined by: (i) the position of the blanket edge 30 along the Y-axis, and (ii) the slopes of the edges 67 and 69. Based on the known slopes of the edges 67 and 69 and the estimated sizes of the reconstructed portions 65a and 65b, the processor 20 and / or the controller 54 are configured to estimate the deformation in the blanket 44 along the Y-axis.

[0222] In some embodiments, based on signals received from the sensors 37 and 38 and indicating the positions of the edges (e.g., the edges 67a and 69a of the isosceles trapezoid 58a), the processor 20 and / or the controller 54 are configured to calculate the average value of the positions of these signals and output a center point, e.g., along the X-axis of the line representing the reconstructed portion 65a. As described above, this averaging reduces the noise in the signal strengths received from the sensors 37 and 38 and thereby improves the accuracy of the position detection and the calculated accuracy of the position and speed of the blanket 44 along the X-axis.

[0223] Although the embodiments described herein are mainly directed to digital printing using a flexible intermediate transfer member, the methods and systems described herein can also be used in other applications, such as for any class of printing systems and processes having any suitable type of intermediate device (e.g., member) for receiving an image and transferring the image to a target substrate.

[0224] Accordingly, it should be understood that the above-described embodiments are cited by way of example, and the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described above, as well as variations and modifications of those features that will occur to those skilled in the art upon reading the foregoing description and that are not disclosed in the prior art. Documents incorporated by reference into this patent application shall be considered an integral part of this application, but in the event of any conflict between any term defined in these incorporated documents and the definitions expressly or implicitly made in this specification, only the definitions in this specification shall be considered.

Claims

1. A system, comprising: An actuator configured to tilt a roller as an intermediate transfer member (ITM) of a printing system moves thereon; And A controller configured to: (i) identify a deformation of the ITM, and (ii) control the actuator to tilt the roller to reduce the deformation as the ITM moves.

2. The system according to claim 1, wherein the ITM moves along a continuous path in a first direction, and the controller is configured to reduce the deformation by: (i) identifying a first moving speed of the ITM in a second direction different from the first direction, and (ii) controlling the actuator to tilt the roller so that the ITM moves at a second moving speed less than the first moving speed as the ITM is moving in the first direction.

3. The system according to claim 2, wherein the controller is configured to receive a signal indicating the first moving speed and control the actuator in response to receiving the signal.

4. The system according to claim 3, comprising: (i) A first side sensor positioned at a first segment of the continuous path and configured to generate a first signal indicating the first moving speed at the first segment; And (ii) A second side sensor positioned at a second segment of the continuous path different from the first segment and configured to generate a second signal indicating the first moving speed at the second segment.

5. The system according to claim 4, wherein in response to receiving the first signal and the second signal, the controller is configured to identify a first deformation in the first segment and a second deformation in the second segment.

6. The system according to claim 5, comprising a first actuator configured to tilt a first roller and a second actuator configured to tilt a second roller, wherein in response to identifying the first deformation and the second deformation, the controller is configured to control at least one of the first actuator and the second actuator to tilt the first roller and the second roller respectively.

7. The system according to claim 6, wherein the controller is configured to: (i) control the first actuator to tilt the first roller at a first tilt angle, and (ii) control the second actuator to tilt the second roller at a second tilt angle different from the first tilt angle.

8. The system according to claim 6, wherein the controller is configured to control the first actuator and the second actuator to apply the first tilt and the second tilt simultaneously.

9. The system according to any one of claims 1 to 8, wherein the ITM is configured to receive ink droplets to form an image thereon and transfer the image to a target substrate.

10. The system according to any one of claims 1 to 8, wherein the controller is configured to: (i) maintain a look-up table (LUT) that includes one or more known deformations caused by one or more operations implemented in the printing system, and (ii) control the actuator to tilt the roller according to the LUT to reduce the one or more known deformations.

11. The system according to claim 10, wherein the one or more known deformations include a first known deformation in a first segment of the ITM and a second known deformation in a second segment of the ITM, and include a first actuator configured to tilt a first roller of the printing system and a second actuator configured to tilt a second roller of the printing system, and wherein in response to identifying the first known deformation and the second known deformation, the controller is configured to control at least one of the first actuator and the second actuator to tilt the first roller and the second roller, respectively.

12. The system according to claim 11, wherein the controller is configured to: (i) control the first actuator to tilt the first roller at a first tilt angle, and (ii) control the second actuator to tilt the second roller at a second tilt angle different from the first tilt angle.

13. The system according to claim 12, wherein the controller is configured to control the first actuator and the second actuator to apply the first tilt and the second tilt simultaneously.

14. The system according to any one of claims 1 to 8, wherein the controller is configured to: (i) maintain a neural network (NN) that is configured to identify one or more known deformations caused by one or more operations implemented in the printing system, and (ii) in response to a given operation in the printing system, control the actuator to tilt the roller according to the output of the NN to reduce the one or more known deformations.

15. The system according to claim 14, wherein the controller is configured to receive one or more signals respectively indicating one or more additional deformations, and wherein the controller is configured to apply the NN to identify whether at least one of the one or more known deformations includes at least one of the one or more additional deformations.

16. The system according to claim 14, wherein the controller is configured to apply the NN to control the actuator in response to receiving the signal.

17. The system according to any one of claims 1 to 8, wherein the printing system includes at least a first roller and a second roller, and wherein the controller is configured to control the actuator to tilt the first roller such that at least the first roller and the second roller are not parallel to each other.

18. The system according to claim 1, wherein the deformation of the ITM causes deflection of the roller, wherein the roller is moved by a driver and includes an encoder configured to generate a deflection signal indicative of the deflection angle of the roller, and wherein the controller is configured to identify the deformation of the ITM based on the deflection signal.

19. The system according to any one of claims 1 to 8, comprising: (i) A chassis and at least a first printing bar and a second printing bar, the printing bars being coupled to the chassis and configured to apply ink droplets of a first color and a second color to the ITM to respectively produce a first pattern and a second pattern of an image on the ITM; and (ii) at least a given edge sensor, the given edge sensor being coupled to the chassis and configured to generate (a) a first edge signal indicative of a first position of the chassis and (b) a second edge signal indicative of a second position of an edge of the ITM moving relative to the at least first printing bar and second printing bar.

20. The system according to claim 19, wherein a deformation in the chassis causes a color-to-color (C2C) registration error between the first pattern and the second pattern of the image, and wherein based on the first edge signal and the second edge signal, the controller is configured to: (i) identify the deformation of the chassis, (ii) estimate the C2C registration error, and (iii) control the actuator to tilt the roller to reduce the C2C registration error by compensating for the deformation of the chassis when (a) moving the ITM and (b) the first printing bar and the second printing bar apply the ink droplets of the first color and the second color.

21. The system according to any one of claims 19 and 20, wherein the controller is configured to control at least the first printing bar and the second printing bar to adjust at least one of a first time and a second time for applying the ink droplets of the first color and the second color respectively to reduce the C2C registration error in the image.

22. The system according to claim 3 or 4, wherein the ITM has a plurality of marks formed at a predefined distance from each other along at least one edge of the ITM, and includes one or more sensors configured to generate a plurality of signals respectively indicative of the plurality of positions of the plurality of marks, and wherein the controller is configured to control at least one of the following based on the plurality of signals: (i) the first moving speed, and (ii) the actuator.

23. The system according to claim 22, wherein at least one of the marks includes a plurality of trapezoids, and wherein the controller is configured to estimate at least one of the following based on the plurality of signals respectively indicative of the plurality of positions of the plurality of trapezoids: (i) the moving speed in the first direction, and (ii) the first moving speed.

24. The system according to claim 23, wherein the plurality of trapezoids includes a plurality of right trapezoids, the plurality of right trapezoids respectively having: (i) a plurality of orthogonal sides that are orthogonal to the first direction; and (ii) a plurality of diagonal sides that extend at a predefined angle with respect to the first direction, and wherein the controller is configured to estimate the moving speed at least in the first direction based on a plurality of signals respectively indicating the respective positions of the orthogonal sides.

25. The system according to claim 24, wherein the plurality of markers comprises: (i) a first marker having a first orthogonal side and a first diagonal side, and (ii) a second marker having a second orthogonal side and a second diagonal side, and wherein the controller is configured to receive a given signal indicating the orthogonal side and the diagonal side, and based on the signal, identify the deformation of the ITM by estimating: (a) a first distance between the first orthogonal side and the first diagonal side, and (b) a second distance between the second orthogonal side and the second diagonal side.

26. The system according to claim 25, wherein in response to the movement of the ITM in the second direction, the controller is configured to: (i) identify the difference between the first distance and the second distance, and (ii) estimate the magnitude of the movement of the ITM in the second direction based on: (a) the estimated difference between the first distance and the second distance, and (b) the predefined angle.

27. The system according to claim 23, wherein the plurality of trapezoids includes a plurality of isosceles trapezoids, the plurality of isosceles trapezoids respectively having: (i) a plurality of third diagonal sides that extend at a first angle with respect to the first direction; and (ii) a plurality of fourth diagonal sides that extend at a second angle with respect to the first direction, wherein the controller is configured to receive a third signal and a fourth signal respectively indicating the third position and the fourth position of the third diagonal side and the fourth diagonal side, wherein the plurality of isosceles trapezoids includes a first isosceles trapezoid and a second isosceles trapezoid located at a given distance, and wherein based on the third signal and the fourth signal, the controller is configured to identify the deformation of the ITM by estimating: (a) a third distance between the third diagonal side and the fourth diagonal side of the first isosceles trapezoid, and (b) a fourth distance between the third diagonal side and the fourth diagonal side of the second isosceles trapezoid.

28. The system according to claim 27, wherein the controller is configured to estimate the magnitude of the movement of the ITM in the second direction based on: (a) the estimated difference between the third distance and the fourth distance, and (b) the first angle and the second angle.

29. The system according to claim 22, wherein at least one of the markings includes one or more polygons having pairs of sides orthogonal to the first direction, and wherein the controller is configured to estimate a moving speed at least in the first direction based on a given signal that respectively indicates a given position of one or more of the pairs of sides.

30. The system according to claim 29, wherein the one or more polygons include one or more rectangles, each of the rectangles having a pair of sides orthogonal to the first direction.

31. The system according to any one of claims 22 to 30, wherein the ITM has a first axis and a second axis orthogonal to the first axis, wherein the marking includes a third marking formed by one or more first sides along the first axis and a fourth marking formed by one or more second sides along the second axis, and wherein the controller is configured to: (i) identify at least one of the following: (a) a third deformation of the ITM based on the third marking, (b) a fourth deformation of the ITM based on the fourth marking, and (c) a fifth deformation of the ITM based on the third marking and the fourth marking; and (ii) control the actuator to tilt the roller to reduce at least one of the third, fourth, and fifth deformations when moving the ITM.

32. The system according to any one of claims 22 to 31, wherein based on at least one of the plurality of signals, the controller is configured to control the operation of at least one station or component of the system.

33. The system according to claim 32, wherein the at least one station or component is selected from the list consisting of: (a) an image forming station configured to apply ink droplets to the ITM and generate an image on the ITM, (b) an impression station configured to transfer the image to a target substrate, (c) at least one roller configured to move the ITM, (d) one or more drying components configured to at least partially dry the ink droplets on the ITM, and (e) an ITM processing station.

34. The system according to claim 32, wherein the impression station includes a rotatable impression cylinder and a rotatable pressure cylinder configured to transfer the image to the target substrate, and wherein based on at least one of the plurality of signals, the controller is configured to control at least one operation selected from the list consisting of: (a) the timing of engagement and disengagement between the impression cylinder and the pressure cylinder, (b) the motion profile of at least one of the impression cylinder and the pressure cylinder, and (c) the size of the gap between the disengaged impression cylinder and the pressure cylinder.

35. A method comprising: identifying a deformation of an intermediate transfer member (ITM) moving on a roller of a printing system; and controlling an actuator to tilt the roller to reduce the deformation when moving the ITM.

36. The method according to claim 35, wherein the ITM moves along a continuous path in a first direction, and wherein reducing the deformation comprises: (i) Identify a first moving speed of the ITM in a second direction different from the first direction, and (ii) tilt the roller to cause the ITM to move at a second moving speed less than the first moving speed while the ITM is moving in the first direction.

37. The method according to claim 36, comprising receiving a signal indicative of the first moving speed and controlling the actuator in response to the received signal.

38. The method according to claim 37, comprising: (i) A first side sensor positioned at a first segment of the continuous path for generating a first signal indicative of the first moving speed at the first segment. And (ii) a second side sensor positioned at a second segment of the continuous path different from the first segment for generating a second signal indicative of the first moving speed at the second segment.

39. The method according to claim 38, comprising identifying a first deformation in the first segment and a second deformation in the second segment in response to receiving the first signal and the second signal.

40. The method according to claim 39, comprising a first actuator for tilting a first roller and a second actuator for tilting a second roller, and comprising controlling at least one of the first actuator and the second actuator to tilt the first roller and the second roller respectively in response to identifying the first deformation and the second deformation.

41. The method according to claim 40, wherein controlling the first actuator and the second actuator comprises: (i) Control the first actuator to tilt the first roller at a first tilt angle, and (ii) control the second actuator to tilt the second roller at a second tilt angle different from the first tilt angle.

42. The method according to claim 40, wherein controlling the first actuator and the second actuator comprises controlling the first actuator and the second actuator to apply the first tilt and the second tilt simultaneously.

43. The method according to any one of claims 35 to 42, comprising receiving ink droplets applied to the ITM to form an ink image thereon and transferring the ink image from the ITM to a target substrate.

44. The method according to any one of claims 35 to 42, wherein controlling the actuator to tilt the roller comprises: (i) Maintain a look-up table (LUT) that includes one or more known deformations caused by one or more operations implemented in the printing system, and (ii) control the actuator to tilt the roller according to the LUT to reduce the one or more known deformations.

45. The method according to claim 44, wherein the one or more known deformations include a first known deformation in a first segment of the ITM and a second known deformation in a second segment of the ITM, and comprising a first actuator for tilting a first roller of the printing system and a second actuator for tilting a second roller of the printing system, and wherein in response to identifying the first known deformation and the second known deformation, controlling at least one of the first actuator and the second actuator to tilt the first roller and the second roller respectively.

46. The method according to claim 45, wherein controlling at least one of the first actuator and the second actuator comprises: (i) Control the first actuator to tilt the first roller at a first tilt angle, and (ii) control the second actuator to tilt the second roller at a second tilt angle different from the first tilt angle.

47. The method according to claim 46, wherein controlling at least one of the first actuator and the second actuator includes controlling the first actuator and the second actuator to simultaneously apply the first tilt and the second tilt.

48. The method according to any one of claims 35 to 42, wherein controlling the actuator to tilt the roller comprises: (i) Maintain a neural network (NN) to identify one or more known deformations caused by one or more operations respectively implemented in the printing system, and (ii) in response to a given operation in the printing system, control the actuator to tilt the roller according to the output of the NN to reduce the one or more known deformations.

49. The method according to claim 48, wherein controlling the actuator to tilt the roller comprises: Receive one or more signals respectively indicating one or more additional deformations, and apply the NN to identify whether at least one of the one or more known deformations includes at least one of the one or more additional deformations.

50. The method according to claim 48, wherein controlling the actuator to tilt the roller comprises: Apply the NN to control the actuator in response to receiving the signal.

51. The method according to any one of claims 35 to 42, wherein the printing system comprises at least a first roller and a second roller, and wherein controlling the actuator to tilt the roller comprises: Control the actuator to tilt the first roller such that at least the first roller and the second roller are not parallel to each other.

52. The method according to any one of claims 35 to 42, wherein the deformation of the ITM causes deflection of the roller and includes moving the ITM and generating a deflection signal indicative of the deflection angle of the roller, and wherein controlling the actuator to tilt the roller comprises: Identify the deformation of the ITM based on the deflection signal.

53. The method according to any one of claims 35 to 42, comprising: (i) A chassis and at least a first printing bar and a second printing bar, the printing bars being coupled to the chassis and configured to apply ink droplets of a first color and a second color to the ITM to respectively produce a first pattern and a second pattern of an image on the ITM; and (ii) at least a given edge sensor, the given edge sensor being coupled to the chassis and configured to generate (a) a first edge signal indicating a first position of the chassis and (b) a second edge signal indicating a second position of an edge of the ITM moving relative to the at least first printing bar and second printing bar.

54. The method according to claim 43, wherein the deformation in the chassis causes a color-to-color (C2C) registration error between the first pattern and the second pattern of the image, and wherein controlling the actuator to tilt the roller based on the first edge signal and the second edge signal comprises: (i) Identify the deformation of the chassis, (ii) estimate the C2C registration error, and (iii) control the actuator to tilt the roller to reduce the C2C registration error by compensating for the deformation of the chassis when (a) moving the ITM and (b) the first printing bar and the second printing bar apply the ink droplets of the first color and the second color.

55. The method according to any one of claims 53 and 54, which includes controlling at least the first printing bar and the second printing bar to respectively adjust at least one of a first time and a second time for applying the ink droplets of the first color and the second color to reduce the C2C registration error in the image.

56. The method according to claim 37 or 38, wherein the ITM has a plurality of markers formed at a predefined distance from each other along at least one side of the ITM, wherein receiving the signal comprises: Receive a plurality of signals respectively indicating the positions of the plurality of markers, and controlling the actuator includes: controlling at least one of the following based on the plurality of signals: (i) the first moving speed, and (ii) the tilt of the roller.

57. The method according to claim 56, wherein at least one of the markers comprises a plurality of trapezoids, and wherein controlling the actuator comprises: Estimate at least one of the following based on a plurality of signals respectively indicating the positions of the plurality of trapezoids: (i) the moving speed in the first direction, and (ii) the first moving speed.

58. The method according to claim 57, wherein the plurality of trapezoids includes a plurality of right trapezoids, and the plurality of right trapezoids respectively have: (i) a plurality of orthogonal sides that are orthogonal to the first direction; and (ii) a plurality of diagonal sides that extend at a predefined angle with respect to the first direction and include: Estimate the movement speed at least in the first direction based on a plurality of signals respectively indicating corresponding positions of the orthogonal sides.

59. The method according to claim 58, wherein the plurality of markers comprises: (i) A first marker having a first orthogonal side and a first diagonal side, and (ii) a second marker having a second orthogonal side and a second diagonal side, and wherein estimating the movement speed at least in the first direction includes: receiving a given signal indicating the orthogonal side and the diagonal side, and based on the signal, identifying the deformation of the ITM by estimating: (a) a first distance between the first orthogonal side and the first diagonal side, and (b) a second distance between the second orthogonal side and the second diagonal side.

60. The method according to claim 59, wherein identifying the deformation comprises: In response to the movement of the ITM in the second direction, (i) identify a difference between the first distance and the second distance, and (ii) estimate the magnitude of the movement of the ITM in the second direction based on: (a) the estimated difference between the first distance and the second distance, and (b) the predefined angle.

61. The method according to claim 57, wherein the plurality of trapezoids includes a plurality of isosceles trapezoids, the plurality of isosceles trapezoids each having: (i) a plurality of third diagonal sides that extend at a first angle relative to the first direction; and (ii) a plurality of fourth diagonal sides that extend at a second angle relative to the first direction, wherein identifying the deformation includes: Receive a third signal and a fourth signal respectively indicating a third position and a fourth position of the third diagonal side and the fourth diagonal side, wherein the plurality of isosceles trapezoids include a first isosceles trapezoid and a second isosceles trapezoid located at a given distance, and wherein identifying the deformation includes: based on the third signal and the fourth signal, identifying the deformation of the ITM by estimating: (a) a third distance between the third diagonal side and the fourth diagonal side of the first isosceles trapezoid, and (b) a fourth distance between the third diagonal side and the fourth diagonal side of the second isosceles trapezoid.

62. The method according to claim 61, wherein identifying the deformation comprises: Estimate the magnitude of the movement of the ITM in the second direction based on: (a) the estimated difference between the third distance and the fourth distance, and (b) the first angle and the second angle.

63. The method according to claim 55, wherein at least one of the markers comprises one or more polygons having pairs of sides orthogonal to the first direction and comprising: Estimate the movement speed at least in the first direction based on a given signal that respectively indicates a given position of one or more of the paired sides.

64. The method according to claim 63, wherein the one or more polygons include one or more rectangles, each of the rectangles having a pair of sides orthogonal to the first direction.

65. The method according to any one of claims 55 to 64, wherein the ITM has a first axis and a second axis orthogonal to the first axis, wherein the markings include a third marking formed along one or more first sides of the first axis, and a fourth marking formed along one or more second sides of the second axis, and wherein (i) identifying the deformation comprises: Identify at least one of: (a) a third deformation of the ITM based on the third marker, (b) a fourth deformation of the ITM based on the fourth marker, and (c) a fifth deformation of the ITM based on the third marker and the fourth marker; and (ii) controlling the actuator includes: controlling the actuator to tilt the roller to reduce at least one of the third, fourth, and fifth deformations when moving the ITM.

66. The method according to any one of claims 56 to 65, which includes controlling the operation of at least one station or component of the printing system based on at least one of the plurality of signals.

67. The method according to claim 66, wherein controlling the operation of the at least one station or component comprises: Control the operation of the station or component that selects from the list consisting of the following: (a) an image forming station for applying ink droplets to the ITM and generating an image on the ITM, (b) an imprinting station for transferring the image to a target substrate, (c) at least one roller for moving the ITM, (d) one or more drying components for at least partially drying the ink droplets on the ITM, and (e) an ITM processing station.

68. The method according to claim 66, wherein the imprinting station includes a rotatable imprinting cylinder and a rotatable pressure cylinder for transferring the ink image to the target substrate, and wherein controlling the operation includes: Based on at least one of the plurality of signals, control at least one operation selected from the list consisting of the following: (a) the timing of engagement and disengagement between the impression cylinder and the pressure cylinder, (b) the motion profile of at least one of the impression cylinder and the pressure cylinder, and (c) the size of the gap between the disengaged impression cylinder and the pressure cylinder.

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